Science.gov

Sample records for nuclear structure simulations

  1. Structural mechanics simulations

    NASA Technical Reports Server (NTRS)

    Biffle, Johnny H.

    1992-01-01

    Sandia National Laboratory has a very broad structural capability. Work has been performed in support of reentry vehicles, nuclear reactor safety, weapons systems and components, nuclear waste transport, strategic petroleum reserve, nuclear waste storage, wind and solar energy, drilling technology, and submarine programs. The analysis environment contains both commercial and internally developed software. Included are mesh generation capabilities, structural simulation codes, and visual codes for examining simulation results. To effectively simulate a wide variety of physical phenomena, a large number of constitutive models have been developed.

  2. Investigation on critical structural motifs of ligands for triggering glucocorticoid receptor nuclear migration through molecular docking simulations.

    PubMed

    Liu, Ya-Lin; Jang, Soonmin; Wang, Shih-Min; Chen, Chiu-Hao; Li, Feng-Yin

    2016-06-01

    The glucocorticoid receptor (GR), a transcription factor regulating gene expression in a ligand-dependent fashion, is known for flexibility in adapting various ligands with their structures ranging from steroid to non-steroid. However, in our previous study, GR shows a stringent discrimination against a set of steroid ligands with highly similar structures for triggering its nuclear migration. In order to resolve this puzzle, we employed molecular docking simulations to investigate the origin of this structural discrimination. By analyzing the docking orientations and the related ligand-GR interaction patterns, we found that the hydrophilicity mismatch between the docking ligand and the GR ligand-binding site is the main cause combined with the steric hindrance and structural rigidness of these steroid ligands. Furthermore, we utilized this knowledge to rationalize how the structure-binding interaction of non-steroid ligands triggers GR nuclear migration with their structures available in Protein Data Bank. PMID:26198481

  3. Frontiers of Nuclear Structure

    SciTech Connect

    Nazarewicz, Witold

    1997-12-31

    Current developments in nuclear structure at the `limits` are discussed. The studies of nuclear behavior at extreme conditions provide us with invaluable information about the nature of the nuclear interaction and nucleonic correlations at various energy-distance scales. In this talk frontiers of nuclear structure are briefly reviewed from a theoretical perspective, mainly concentrating on medium-mass and heavy nuclei.

  4. WE-D-BRF-01: FEATURED PRESENTATION - Investigating Particle Track Structures Using Fluorescent Nuclear Track Detectors and Monte Carlo Simulations

    SciTech Connect

    Dowdell, S; Paganetti, H; Schuemann, J; Greilich, S; Zimmerman, F; Evans, C

    2014-06-15

    Purpose: To report on the efforts funded by the AAPM seed funding grant to develop the basis for fluorescent nuclear track detector (FNTD) based radiobiological experiments in combination with dedicated Monte Carlo simulations (MCS) on the nanometer scale. Methods: Two confocal microscopes were utilized in this study. Two FNTD samples were used to find the optimal microscope settings, one FNTD irradiated with 11.1 MeV/u Gold ions and one irradiated with 428.77 MeV/u Carbon ions. The first sample provided a brightly luminescent central track while the latter is used to test the capabilities to observe secondary electrons. MCS were performed using TOPAS beta9 version, layered on top of Geant4.9.6p02. Two sets of simulations were performed, one with the Geant4-DNA physics list and approximating the FNTDs by water, a second set using the Penelope physics list in a water-approximated FNTD and a aluminum-oxide FNTD. Results: Within the first half of the funding period, we have successfully established readout capabilities of FNTDs at our institute. Due to technical limitations, our microscope setup is significantly different from the approach implemented at the DKFZ, Germany. However, we can clearly reconstruct Carbon tracks in 3D with electron track resolution of 200 nm. A second microscope with superior readout capabilities will be tested in the second half of the funding period, we expect an improvement in signal to background ratio with the same the resolution.We have successfully simulated tracks in FNTDs. The more accurate Geant4-DNA track simulations can be used to reconstruct the track energy from the size and brightness of the observed tracks. Conclusion: We have achieved the goals set in the seed funding proposal: the setup of FNTD readout and simulation capabilities. We will work on improving the readout resolution to validate our MCS track structures down to the nanometer scales.

  5. Solution-state structure and affinities of cyclodextrin: Fentanyl complexes by nuclear magnetic resonance spectroscopy and molecular dynamics simulation

    DOE PAGESBeta

    Mayer, Brian P.; Kennedy, Daniel J.; Lau, Edmond Y.; Valdez, Carlos A.

    2016-02-04

    Cyclodextrins (CDs) are investigated for their ability to form inclusion complexes with the analgesic fentanyl and three similar molecules: acetylfentanyl, thiofentanyl, and acetylthiofentanyl. Stoichiometry, binding strength, and complex structure are revealed through nuclear magnetic resonance (NMR) techniques and discussed in terms of molecular dynamics (MD) simulations. It was found that β-cyclodextrin is generally capable of forming the strongest complexes with the fentanyl panel. Two-dimensional NMR data and computational chemical calculations are used to derive solution-state structures of the complexes. Binding of the fentanyls to the CDs occurs at the amide phenyl ring, leaving the majority of the molecule solvated bymore » water, an observation common to all four fentanyls. This finding suggests a universal binding behavior, as the vast majority of previously synthesized fentanyl analogues contain this structural moiety. Furthermore, this baseline study serves as the most complete work on CD:fentanyl complexes to date and provides the insights into strategies for producing future generations of designer cyclodextrins capable of stronger and more selective complexation of fentanyl and its analogues.« less

  6. Nuclear Power Plant Simulation Game.

    ERIC Educational Resources Information Center

    Weiss, Fran

    1979-01-01

    Presents a nuclear power plant simulation game which is designed to involve a class of 30 junior or senior high school students. Scientific, ecological, and social issues covered in the game are also presented. (HM)

  7. Dynamic Simulation Nuclear Power Plants

    Energy Science and Technology Software Center (ESTSC)

    1992-03-03

    DSNP (Dynamic Simulator for Nuclear Power-Plants) is a system of programs and data files by which a nuclear power plant, or part thereof, can be simulated. The acronym DSNP is used interchangeably for the DSNP language, the DSNP libraries, the DSNP precompiler, and the DSNP document generator. The DSNP language is a special-purpose, block-oriented, digital-simulation language developed to facilitate the preparation of dynamic simulations of a large variety of nuclear power plants. It is amore » user-oriented language that permits the user to prepare simulation programs directly from power plant block diagrams and flow charts by recognizing the symbolic DSNP statements for the appropriate physical components and listing these statements in a logical sequence according to the flow of physical properties in the simulated power plant. Physical components of nuclear power plants are represented by functional blocks, or modules. Many of the more complex components are represented by several modules. The nuclear reactor, for example, has a kinetic module, a power distribution module, a feedback module, a thermodynamic module, a hydraulic module, and a radioactive heat decay module. These modules are stored in DSNP libraries in the form of a DSNP subroutine or function, a block of statements, a macro, or a combination of the above. Basic functional blocks such as integrators, pipes, function generators, connectors, and many auxiliary functions representing properties of materials used in nuclear power plants are also available. The DSNP precompiler analyzes the DSNP simulation program, performs the appropriate translations, inserts the requested modules from the library, links these modules together, searches necessary data files, and produces a simulation program in FORTRAN.« less

  8. High energy nuclear structures

    SciTech Connect

    Boguta, J.; Kunz, J.

    1984-03-09

    In conventional nuclear physics the nucleus is described as a non-relativistic many-body system, which is governed by the Schroedinger equation. Nucleons interact in this framework via static two-body potentials, mesonic degrees of freedom are neglected. An alternative description of nuclear physics in terms of a relativistic field theory has been developed by Walecka. The model Lagrangian containing baryons, sigma-mesons and ..omega..-mesons was subsequently extended to include also ..pi..-mesons and rho-mesons. An essential feature of such a nuclear Lagrangian is its renormalizability. In addition to the description of known nuclear structure the field theoretical approach may reveal entirely new nuclear phenomena, based on the explicit treatment of mesonic degrees of freedom. The existence of such abnormal nuclear states was proposed by Lee and Wick employing the sigma-model Lagrangian. There the non-linearity of the meson field equations allows for soliton solutions in the presence of nucleons, in particular the sigma-field may exhibit a kink. Different types of soliton solutions occur in gauge theories with hidden symmetries. In the phenomenological Lagrangian the rho-meson is described by a non-abelian gauge field, that acquires its mass spontaneously due to the non-vanishing vacuum expectation value of a Higgs field. A general ansatz for soliton solutions of such a gauge theory was given by Dashen et al. A specific solution and its possible implications for nuclear physics like anomalous nuclear states were discussed by Boguta.

  9. Extremes of nuclear structure

    NASA Astrophysics Data System (ADS)

    1999-09-01

    With the advent of medium and large gamma detector arrays, it is now possible to look at nuclear structure at high rotational forces. The role of pairing correlations and their eventual breakdown, along with the shell effects have showed us the interesting physics for nuclei at high spins - superdeformation, shape co-existence, yrast traps, alignments and their dramatic effects on nuclear structure and so on. Nuclear structure studies have recently become even more exciting, due to efforts and possibilities to reach nuclei far off from the stability valley. Coupling of gamma ray arrays with 'filters', like neutron wall, charged particle detector array, gamma ray total energy and multiplicity castles, conversion electron spectrometers etc gives a great handle to study nuclei produced online with 'low' cross-sections. Recently we studied, nuclei in mass region 80 using an array of 8 germanium detectors in conjunction with the recoil mass analyser, HIRA at the Nuclear Science Centre and, most unexpectedly came across the phenomenon of identical bands, with two quasi-particle difference. The discovery of magnetic rotation is another highlight. Our study of light In nucleus, 107In brought us face to face with the 'dipole' bands. I plan to discuss some of these aspects. There is also an immensely important development - that of the 'radioactive ion beams'. The availability of RIB, will probably very dramatically influence our 'conventional' concept of nuclear structure. The exotic shapes of these exotic nuclei and some of their expected properties will also be touched upon.

  10. Special nuclear material simulation device

    SciTech Connect

    Leckey, John H.; DeMint, Amy; Gooch, Jack; Hawk, Todd; Pickett, Chris A.; Blessinger, Chris; York, Robbie L.

    2014-08-12

    An apparatus for simulating special nuclear material is provided. The apparatus typically contains a small quantity of special nuclear material (SNM) in a configuration that simulates a much larger quantity of SNM. Generally the apparatus includes a spherical shell that is formed from an alloy containing a small quantity of highly enriched uranium. Also typically provided is a core of depleted uranium. A spacer, typically aluminum, may be used to separate the depleted uranium from the shell of uranium alloy. A cladding, typically made of titanium, is provided to seal the source. Methods are provided to simulate SNM for testing radiation monitoring portals. Typically the methods use at least one primary SNM spectral line and exclude at least one secondary SNM spectral line.

  11. Understanding of the mechanical and structural changes induced by alpha particles and heavy ions in the French simulated nuclear waste glass

    NASA Astrophysics Data System (ADS)

    Karakurt, G.; Abdelouas, A.; Guin, J.-P.; Nivard, M.; Sauvage, T.; Paris, M.; Bardeau, J.-F.

    2016-07-01

    Borosilicate glasses are considered for the long-term confinement of high-level nuclear wastes. External irradiations with 1 MeV He+ ions and 7 MeV Au5+ ions were performed to simulate effects produced by alpha particles and by recoil nuclei in the simulated SON68 nuclear waste glass. To better understand the structural modifications, irradiations were also carried out on a 6-oxides borosilicate glass, a simplified version of the SON68 glass (ISG glass). The mechanical and macroscopic properties of the glasses were studied as function of the deposited electronic and nuclear energies. Alpha particles and gold ions induced a volume change up to -0.7% and -2.7%, respectively, depending on the glass composition. Nano-indentations tests were used to determine the mechanical properties of the irradiated glasses. A decrease of about -22% to -38% of the hardness and a decrease of the reduced Young's modulus by -8% were measured after irradiations. The evolution of the glass structure was studied by Raman spectroscopy, and also 11B and 27Al Nuclear Magnetic Resonance (MAS-NMR) on a 20 MeV Kr irradiated ISG glass powder. A decrease of the silica network connectivity after irradiation with alpha particles and gold ions is deduced from the structural changes observations. NMR spectra revealed a partial conversion of BO4 to BO3 units but also a formation of AlO5 and AlO6 species after irradiation with Kr ions. The relationships between the mechanical and structural changes are also discussed.

  12. Non Nuclear NTR Environmental Simulator

    SciTech Connect

    Emrich, William J. Jr.

    2006-01-20

    Nuclear Thermal Rockets or NTR's have been suggested as a propulsion system option for vehicles traveling to the moon or Mars. These engines are capable of providing high thrust at specific impulses at least twice that of today's best chemical engines. The performance constraints on these engines are mainly the result of temperature limitations on the fuel coupled with a limited ability to withstand chemical attack by the hot hydrogen propellant. To operate at maximum efficiency, fuel forms are desired which can withstand the extremely hot, hostile environment characteristic of NTR operation for at least several hours. The simulation of such an environment would require an experimental device which could simultaneously approximate the power, flow, and temperature conditions which a nuclear fuel element (or partial element) would encounter during NTR operation. Such a simulation would allow detailed studies of the fuel behavior and hydrogen flow characteristics under reactor like conditions to be performed. The goal of these simulations would be directed toward expanding the performance envelope of NTR engines over that which was demonstrated during the Rover and NERVA nuclear rocket programs of the 1970's. Current planning calls for such a simulator to be constructed at the Marshall Space Flight Center over the coming year, and it is anticipated that it will be used in the future to evaluate a wide variety of fuel element designs and the materials of which they are constructed. This present work addresses the initial experimental objectives of the NTR simulator with regard to reproducing the fuel degradation patterns previously observed during the NERVA testing.

  13. Rotational spectra, nuclear quadrupole hyperfine tensors, and conformational structures of the mustard gas simulent 2-chloroethyl ethyl sulfide

    NASA Astrophysics Data System (ADS)

    Tubergen, M. J.; Lesarri, A.; Suenram, R. D.; Samuels, A. C.; Jensen, J. O.; Ellzy, M. W.; Lochner, J. M.

    2005-10-01

    Rotational spectra have been recorded for both the 35Cl and 37Cl isotopic forms of two structural conformations of 2-chloroethyl ethyl sulfide (CEES). The rotational constants of the 35Cl and 37Cl isotopomers were used to identify the conformational isomers. A total of 236 hyperfine transitions have been assigned for 47 rotational transitions of the 35Cl isotope of a GGT conformer, and 146 hyperfine have been assigned for 37 rotational transitions of the 37Cl isotopomer. For the second conformer, a total of 128 (110) hyperfine and 30 (28) rotational transitions have also been assigned to the 35Cl ( 37Cl) isotopes of a TGT conformation. The extensive hyperfine splitting data, measured to high resolution with a compact Fourier transform microwave spectrometer, were used to determine both the diagonal and off-diagonal elements of the 35Cl and 37Cl nuclear quadrupole coupling tensors in the inertial tensor principal axis system. The experimental rotational constant data, as well as the 35Cl and 37Cl nuclear quadrupole coupling tensors, were compared to the results from 27 optimized ab initio (HF/6-311++G ∗∗ and MP2/6-311++G ∗∗) model structures.

  14. Deconvoluting Protein (Un)folding Structural Ensembles Using X-Ray Scattering, Nuclear Magnetic Resonance Spectroscopy and Molecular Dynamics Simulation

    PubMed Central

    Nasedkin, Alexandr; Marcellini, Moreno; Religa, Tomasz L.; Freund, Stefan M.; Menzel, Andreas; Fersht, Alan R.; Jemth, Per; van der Spoel, David; Davidsson, Jan

    2015-01-01

    The folding and unfolding of protein domains is an apparently cooperative process, but transient intermediates have been detected in some cases. Such (un)folding intermediates are challenging to investigate structurally as they are typically not long-lived and their role in the (un)folding reaction has often been questioned. One of the most well studied (un)folding pathways is that of Drosophila melanogaster Engrailed homeodomain (EnHD): this 61-residue protein forms a three helix bundle in the native state and folds via a helical intermediate. Here we used molecular dynamics simulations to derive sample conformations of EnHD in the native, intermediate, and unfolded states and selected the relevant structural clusters by comparing to small/wide angle X-ray scattering data at four different temperatures. The results are corroborated using residual dipolar couplings determined by NMR spectroscopy. Our results agree well with the previously proposed (un)folding pathway. However, they also suggest that the fully unfolded state is present at a low fraction throughout the investigated temperature interval, and that the (un)folding intermediate is highly populated at the thermal midpoint in line with the view that this intermediate can be regarded to be the denatured state under physiological conditions. Further, the combination of ensemble structural techniques with MD allows for determination of structures and populations of multiple interconverting structures in solution. PMID:25946337

  15. Simulation of phase structures

    SciTech Connect

    Lawson, J.

    1995-04-20

    This memo outlines a procedure developed by the author to extract information from phase measurements and produce a simulated phase structure for use in modeling optical systems, including characteristic optics for the Beamlet and NIF laser systems. The report includes an IDL program listing.

  16. Simulated nuclear reactor fuel assembly

    DOEpatents

    Berta, V.T.

    1993-04-06

    An apparatus for electrically simulating a nuclear reactor fuel assembly. It includes a heater assembly having a top end and a bottom end and a plurality of concentric heater tubes having electrical circuitry connected to a power source, and radially spaced from each other. An outer target tube and an inner target tube is concentric with the heater tubes and with each other, and the outer target tube surrounds and is radially spaced from the heater tubes. The inner target tube is surrounded by and radially spaced from the heater tubes and outer target tube. The top of the assembly is generally open to allow for the electrical power connection to the heater tubes, and the bottom of the assembly includes means for completing the electrical circuitry in the heater tubes to provide electrical resistance heating to simulate the power profile in a nuclear reactor. The embedded conductor elements in each heater tube is split into two halves for a substantial portion of its length and provided with electrical isolation such that each half of the conductor is joined at one end and is not joined at the other end.

  17. Simulated nuclear reactor fuel assembly

    DOEpatents

    Berta, Victor T.

    1993-01-01

    An apparatus for electrically simulating a nuclear reactor fuel assembly. It includes a heater assembly having a top end and a bottom end and a plurality of concentric heater tubes having electrical circuitry connected to a power source, and radially spaced from each other. An outer target tube and an inner target tube is concentric with the heater tubes and with each other, and the outer target tube surrounds and is radially spaced from the heater tubes. The inner target tube is surrounded by and radially spaced from the heater tubes and outer target tube. The top of the assembly is generally open to allow for the electrical power connection to the heater tubes, and the bottom of the assembly includes means for completing the electrical circuitry in the heater tubes to provide electrical resistance heating to simulate the power profile in a nuclear reactor. The embedded conductor elements in each heater tube is split into two halves for a substantial portion of its length and provided with electrical isolation such that each half of the conductor is joined at one end and is not joined at the other end.

  18. Structure and conformational dynamics of the domain 5 RNA hairpin of a bacterial group II intron revealed by solution nuclear magnetic resonance and molecular dynamics simulations.

    PubMed

    Pechlaner, Maria; Sigel, Roland K O; van Gunsteren, Wilfred F; Dolenc, Jožica

    2013-10-01

    Nuclear magnetic resonance (NMR) nuclear Overhauser enhancement (NOE) data obtained for a 35-nucleotide RNA segment of a bacterial group II intron indicate a helical hairpin structure in which three parts, a terminal pentaloop, a bulge, and a G-A mismatch, display no Watson-Crick base pairing. The 668 NOE upper distance bounds for atom pairs are insufficient to uniquely determine the conformation of these segments. Therefore, molecular dynamics simulations including time-averaged distance restraints have been used to obtain a conformational ensemble compatible with the observed NMR data. The ensemble shows alternating hydrogen bonding patterns for the mentioned segments. In particular, in the pentaloop and in the bulge, the hydrogen bonding networks correspond to distinct conformational clusters that could not be captured by using conventional single-structure refinement techniques. This implies that, to obtain a realistic picture of the conformational ensemble of such flexible biomolecules, it is necessary to properly account for the conformational variability in the structure refinement of RNA fragments. PMID:24001362

  19. Teaching About Nuclear Power: A Simulation.

    ERIC Educational Resources Information Center

    Maxey, Phyllis F.

    1980-01-01

    Recommends that simulation games be used to teach high school students in social studies courses about contemporary and controversial issues such as nuclear power. A simulation is described which involves students in deciding whether to build a nuclear power plant in the California desert. Teaching and debriefing tips are also provided. (DB)

  20. Challenges in nuclear structure theory

    NASA Astrophysics Data System (ADS)

    Nazarewicz, W.

    2016-08-01

    The goal of nuclear structure theory is to build a comprehensive microscopic framework in which properties of nuclei and extended nuclear matter, and nuclear reactions and decays can all be consistently described. Due to novel theoretical concepts, breakthroughs in the experimentation with rare isotopes, increased exchange of ideas across different research areas, and the progress in computer technologies and numerical algorithms, nuclear theorists have been quite successful in solving various bits and pieces of the nuclear many-body puzzle and the prospects are exciting. This article contains a brief, personal perspective on the status of the field.

  1. Evaluated nuclear structure data file

    NASA Astrophysics Data System (ADS)

    Tuli, J. K.

    1996-02-01

    The Evaluated Nuclear Structure Data File (ENSDF) contains the evaluated nuclear properties of all known nuclides, as derived both from nuclear reaction and radioactive decay measurements. All experimental data are evaluated to create the adopted properties for each nuclide. ENSDF, together with other numeric and bibliographic files, can be accessed on-line through the INTERNET or modem, and some of the databases are also available on the World Wide Web. The structure and the scope of ENSDF are presented along with the on-line access system of the National Nuclear Data Center at Brookhaven National Laboratory.

  2. Evaluated nuclear structure data file

    NASA Astrophysics Data System (ADS)

    Tuli, J. K.

    The Evaluated Nuclear Structure Data File (ENSDF) contains the evaluated nuclear properties of all known nuclides. These properties are derived both from nuclear reaction and radioactive decay measurements. All experimental data are evaluated to create the adopted properties for each nuclide. ENSDF, together with other numeric and biographic files, can be accessed on-line through the INTERNET or modem. Some of the databases are also available on the World Wide Web. The structure and the scope of ENSDF are presented along with the on-line access system of the National Nuclear Data Center at Brookhaven National Laboratory.

  3. Used Nuclear Fuel Loading and Structural Performance Under Normal Conditions of Transport - Modeling, Simulation and Experimental Integration RD&D Plan

    SciTech Connect

    Adkins, Harold E.

    2013-04-01

    Under current U.S. Nuclear Regulatory Commission regulation, it is not sufficient for used nuclear fuel (UNF) to simply maintain its integrity during the storage period, it must maintain its integrity in such a way that it can withstand the physical forces of handling and transportation associated with restaging the fuel and moving it to treatment or recycling facilities, or a geologic repository. Hence it is necessary to understand the performance characteristics of aged UNF cladding and ancillary components under loadings stemming from transport initiatives. Researchers would like to demonstrate that enough information, including experimental support and modeling and simulation capabilities, exists to establish a preliminary determination of UNF structural performance under normal conditions of transport (NCT). This research, development and demonstration (RD&D) plan describes a methodology, including development and use of analytical models, to evaluate loading and associated mechanical responses of UNF rods and key structural components. This methodology will be used to provide a preliminary assessment of the performance characteristics of UNF cladding and ancillary components under rail-related NCT loading. The methodology couples modeling and simulation and experimental efforts currently under way within the Used Fuel Disposition Campaign (UFDC). The methodology will involve limited uncertainty quantification in the form of sensitivity evaluations focused around available fuel and ancillary fuel structure properties exclusively. The work includes collecting information via literature review, soliciting input/guidance from subject matter experts, performing computational analyses, planning experimental measurement and possible execution (depending on timing), and preparing a variety of supporting documents that will feed into and provide the basis for future initiatives. The methodology demonstration will focus on structural performance evaluation of

  4. Nuclear Structure at the Limits

    SciTech Connect

    Nazarewicz, Witold

    1997-12-31

    One of the frontiers of today`s nuclear science is the ``journey to the limits``: of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The tour to the limits is not only a quest for new, exciting phenomena but the new data are expected, as well, to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure at the limits are discussed from a theoretical perspective.

  5. Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael

    2009-01-01

    A detailed description of the Nuclear Thermal Rocket Element Environmental Simulator (NTREES) is presented. The contents include: 1) Design Requirements; 2) NTREES Layout; 3) Data Acquisition and Control System Schematics; 4) NTREES System Schematic; and 5) NTREES Setup.

  6. Computational Challenges in Nuclear Weapons Simulation

    SciTech Connect

    McMillain, C F; Adams, T F; McCoy, M G; Christensen, R B; Pudliner, B S; Zika, M R; Brantley, P S; Vetter, J S; May, J M

    2003-08-29

    After a decade of experience, the Stockpile Stewardship Program continues to ensure the safety, security and reliability of the nation's nuclear weapons. The Advanced Simulation and Computing (ASCI) program was established to provide leading edge, high-end simulation capabilities needed to meet the program's assessment and certification requirements. The great challenge of this program lies in developing the tools and resources necessary for the complex, highly coupled, multi-physics calculations required to simulate nuclear weapons. This paper describes the hardware and software environment we have applied to fulfill our nuclear weapons responsibilities. It also presents the characteristics of our algorithms and codes, especially as they relate to supercomputing resource capabilities and requirements. It then addresses impediments to the development and application of nuclear weapon simulation software and hardware and concludes with a summary of observations and recommendations on an approach for working with industry and government agencies to address these impediments.

  7. Functional evolution of nuclear structure

    PubMed Central

    Dawson, Scott C.

    2011-01-01

    The evolution of the nucleus, the defining feature of eukaryotic cells, was long shrouded in speculation and mystery. There is now strong evidence that nuclear pore complexes (NPCs) and nuclear membranes coevolved with the endomembrane system, and that the last eukaryotic common ancestor (LECA) had fully functional NPCs. Recent studies have identified many components of the nuclear envelope in living Opisthokonts, the eukaryotic supergroup that includes fungi and metazoan animals. These components include diverse chromatin-binding membrane proteins, and membrane proteins with adhesive lumenal domains that may have contributed to the evolution of nuclear membrane architecture. Further discoveries about the nucleoskeleton suggest that the evolution of nuclear structure was tightly coupled to genome partitioning during mitosis. PMID:22006947

  8. Nuclear structure from radioactive decay

    SciTech Connect

    Wood, J.L.

    1991-09-30

    This report discusses nuclear structure from radioactive decay of the following: Neutron-Deficient Iridium Isotopes; Neutron-Deficient Platinum Isotopes; Neutron-Deficient Gold Isotopes; Neutron-Deficient Mercury Isotopes; Neutron-Deficient Thallium Isotopes; Neutron-Deficient Lead Isotopes; Neutron-Deficient Samarium Isotopes; Neutron-Deficient Promethium Isotopes; Neutron-Deficient Neodymium Isotopes; and Neutron-Deficient Praseodymium Isotopes. Also discussed are Nuclear Systematics and Models.

  9. Uniquely designed nuclear structures of lower eukaryotes.

    PubMed

    Iwamoto, Masaaki; Hiraoka, Yasushi; Haraguchi, Tokuko

    2016-06-01

    The nuclear structures of lower eukaryotes, specifically protists, often vary from those of yeasts and metazoans. Several studies have demonstrated the unique and fascinating features of these nuclear structures, such as a histone-independent condensed chromatin in dinoflagellates and two structurally distinct nuclear pore complexes in ciliates. Despite their unique molecular/structural features, functions required for formation of their cognate molecules/structures are highly conserved. This provides important information about the structure-function relationship of the nuclear structures. In this review, we highlight characteristic nuclear structures found in lower eukaryotes, and discuss their attractiveness as potential biological systems for studying nuclear structures. PMID:26963276

  10. Hyperthermal Environments Simulator for Nuclear Rocket Engine Development

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.; Foote, John P.; Clifton, W. B.; Hickman, Robert R.; Wang, Ten-See; Dobson, Christopher C.

    2011-01-01

    An arc-heater driven hyperthermal convective environments simulator was recently developed and commissioned for long duration hot hydrogen exposure of nuclear thermal rocket materials. This newly established non-nuclear testing capability uses a high-power, multi-gas, wall-stabilized constricted arc-heater to produce hightemperature pressurized hydrogen flows representative of nuclear reactor core environments, excepting radiation effects, and is intended to serve as a low-cost facility for supporting non-nuclear developmental testing of hightemperature fissile fuels and structural materials. The resulting reactor environments simulator represents a valuable addition to the available inventory of non-nuclear test facilities and is uniquely capable of investigating and characterizing candidate fuel/structural materials, improving associated processing/fabrication techniques, and simulating reactor thermal hydraulics. This paper summarizes facility design and engineering development efforts and reports baseline operational characteristics as determined from a series of performance mapping and long duration capability demonstration tests. Potential follow-on developmental strategies are also suggested in view of the technical and policy challenges ahead. Keywords: Nuclear Rocket Engine, Reactor Environments, Non-Nuclear Testing, Fissile Fuel Development.

  11. Nuclear Structure at the Limits

    SciTech Connect

    Nazarewicz, W.

    1998-01-12

    One of the frontiers of today�s nuclear science is the �journey to the limits� of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The tour to the limits is not only a quest for new, exciting phenomena, but the new data are expected, as well, to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this series of lectures, current developments in nuclear structure at the limits are discussed from a theoretical perspective, mainly concentrating on medium-mass and heavy nuclei.

  12. Changing Facets of Nuclear Structure

    NASA Astrophysics Data System (ADS)

    Covello, Aldo

    2008-04-01

    Section I. Exotic nuclear structure. Radioactive beams at TRIUMF / A. C. Shotter. Status of RI-beam factory project at RIKEN / H. Ueno. Population of neutron unbound states via two-proton knockout reactions / N. Frank ... [et al.]. Studies of neutron-rich nuclei using ISOL facilities at CERN and Jyväskylä / J. Äystö. Shell structure evolution far from stability: recent results from GANIL / F. Azaiez. Magnetic moment meaurements: pushing the limits / N. Benczer-Koller. Technique for measuring angular correlations and g-factors of excited states with large multi-detector arrays: an application to neutron rich nuclei produced in spontaneous fission / A. V. Ramayya ... [et al.]. Isospin symmetry and proton decay: identification of the 10+ isomer in [symbol]Ni / C. Fahlander ... [et al.]. Exploring the evolution of the shell structure by means of deep inelastic reactions / G. de Angelis. Studies on the exotic structure of [symbol]Al by measurements of [symbol] and P[symbol] / D. Q. Fang ... [et al.]. Extended cluster model for light and medium nuclei / M. Tomaselli ... [et al.]. Nuclear structure studies on exotic nuclei with radioactive beams - present status and future perspectives at FAIR / P. Egelhof. The SPES direct target project at the Laboratori Nazionali di Legnaro / G. Prete ... [et al.] -- Section II. Nuclear structure and nuclear forces. Modern aspects of nuclear structure theory / J. Wambach. Correlations in nuclei: a review / R. Schiavilla. Correlated nucleons in k- and r-space / I. Sick. Roles of all-order core polarizations and Brown-Rho scaling in nucleon effective interactions / T. T. S. Kuo ... [et al.]. Ab initio and ab exitu no core shell model / J. P. Vary ... [et al.]. Ab-initio coupled cluster theory for open quantum systems / G. Hagen ... [et al.]. Symplectic no-core shell model / J. P. Draayer ... [et al.]. Role of deformed symplectic configurations in ab initio no-core shell model results / T. Dytrych ... [et al.]. Nuclear structure

  13. Large Scale Quantum Simulations of Nuclear Pasta

    NASA Astrophysics Data System (ADS)

    Fattoyev, Farrukh J.; Horowitz, Charles J.; Schuetrumpf, Bastian

    2016-03-01

    Complex and exotic nuclear geometries collectively referred to as ``nuclear pasta'' are expected to naturally exist in the crust of neutron stars and in supernovae matter. Using a set of self-consistent microscopic nuclear energy density functionals we present the first results of large scale quantum simulations of pasta phases at baryon densities 0 . 03 < ρ < 0 . 10 fm-3, proton fractions 0 . 05 simulations, in particular, allow us to also study the role and impact of the nuclear symmetry energy on these pasta configurations. This work is supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  14. Nuclear structure from radioactive decay

    SciTech Connect

    Wood, J.L.

    1990-09-30

    This report discusses the nuclear structure of the following isotopes as a result of radioactive decays: neutron-deficient iridium isotopes; neutron-deficient platinum isotopes; neutron-deficient gold isotopes; neutron-deficient mercury isotopes; neutron-deficient thallium isotopes; neutron-deficient lead isotopes; neutron-deficient promethium isotopes; and neutron-deficient samarium isotopes.

  15. Modeling and Simulation of Nuclear Fuel Materials

    SciTech Connect

    Devanathan, Ram; Van Brutzel, Laurent; Tikare, Veena; Bartel, Timothy; Besmann, Theodore M; Stan, Marius; Van Uffelen, Paul

    2010-01-01

    We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios and small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.

  16. Modeling and Simulation of Nuclear Fuel Materials

    SciTech Connect

    Devanathan, Ramaswami; Van Brutzel, Laurent; Chartier, Alan; Gueneau, Christine; Mattsson, Ann E.; Tikare, Veena; Bartel, Timothy; Besmann, T. M.; Stan, Marius; Van Uffelen, Paul

    2010-10-01

    We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios, and the small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.

  17. Nuclear Quadrupole Moments and Nuclear Shell Structure

    DOE R&D Accomplishments Database

    Townes, C. H.; Foley, H. M.; Low, W.

    1950-06-23

    Describes a simple model, based on nuclear shell considerations, which leads to the proper behavior of known nuclear quadrupole moments, although predictions of the magnitudes of some quadrupole moments are seriously in error.

  18. Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    SciTech Connect

    Emrich, William J. Jr.

    2008-01-21

    To support a potential future development of a nuclear thermal rocket engine, 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 test device simulates the environmental conditions (minus the radiation) to which nuclear rocket fuel components could be subjected during reactor operation. Test articles mounted in the simulator are inductively heated in such a manner as to accurately reproduce the temperatures and heat fluxes normally expected to occur as a result of nuclear fission while at the same time being exposed to flowing hydrogen. This project is referred to as the Nuclear Thermal Rocket Element Environment Simulator or NTREES. The NTREES device is located at the Marshall Space flight Center in a laboratory which has been modified to accommodate the high powers required to heat the test articles to the required temperatures and to handle the gaseous hydrogen flow required for the tests. Other modifications to the laboratory include the installation of a nitrogen gas supply system and a cooling water supply system. During the design and construction of the facility, every effort was made to comply with all pertinent regulations to provide assurance that the facility could be operated in a safe and efficient manner. The NTREES system can currently supply up to 50 kW of inductive heating to the fuel test articles, although the facility has been sized to eventually allow test article heating levels of up to several megawatts.

  19. Fully dynamical simulation of central nuclear collisions.

    PubMed

    van der Schee, Wilke; Romatschke, Paul; Pratt, Scott

    2013-11-27

    We present a fully dynamical simulation of central nuclear collisions around midrapidity at LHC energies. Unlike previous treatments, we simulate all phases of the collision, including the equilibration of the system. For the simulation, we use numerical relativity solutions to anti-de Sitter space/conformal field theory for the preequilibrium stage, viscous hydrodynamics for the plasma equilibrium stage, and kinetic theory for the low-density hadronic stage. Our preequilibrium stage provides initial conditions for hydrodynamics, resulting in sizable radial flow. The resulting light particle spectra reproduce the measurements from the ALICE experiment at all transverse momenta. PMID:24329444

  20. Nuclear structure references coding manual

    SciTech Connect

    Ramavataram, S.; Dunford, C.L.

    1984-02-01

    This manual is intended as a guide to Nuclear Structure References (NSR) compilers. The basic conventions followed at the National Nuclear Data Center (NNDC), which are compatible with the maintenance and updating of and retrieval from the Nuclear Structure References (NSR) file, are outlined. The structure of the NSR file such as the valid record identifiers, record contents, text fields as well as the major topics for which (KEYWORDS) are prepared are ennumerated. Relevant comments regarding a new entry into the NSR file, assignment of (KEYNO ), generation of (SELECTRS) and linkage characteristics are also given. A brief definition of the Keyword abstract is given followed by specific examples; for each TOPIC, the criteria for inclusion of an article as an entry into the NSR file as well as coding procedures are described. Authors submitting articles to Journals which require Keyword abstracts should follow the illustrations. The scope of the literature covered at NNDC, the categorization into Primary and Secondary sources, etc. is discussed. Useful information regarding permitted character sets, recommended abbreviations, etc. is given.

  1. Monte Carlo simulations in Nuclear Medicine

    SciTech Connect

    Loudos, George K.

    2007-11-26

    Molecular imaging technologies provide unique abilities to localise signs of disease before symptoms appear, assist in drug testing, optimize and personalize therapy, and assess the efficacy of treatment regimes for different types of cancer. Monte Carlo simulation packages are used as an important tool for the optimal design of detector systems. In addition they have demonstrated potential to improve image quality and acquisition protocols. Many general purpose (MCNP, Geant4, etc) or dedicated codes (SimSET etc) have been developed aiming to provide accurate and fast results. Special emphasis will be given to GATE toolkit. The GATE code currently under development by the OpenGATE collaboration is the most accurate and promising code for performing realistic simulations. The purpose of this article is to introduce the non expert reader to the current status of MC simulations in nuclear medicine and briefly provide examples of current simulated systems, and present future challenges that include simulation of clinical studies and dosimetry applications.

  2. Monte Carlo simulations in Nuclear Medicine

    NASA Astrophysics Data System (ADS)

    Loudos, George K.

    2007-11-01

    Molecular imaging technologies provide unique abilities to localise signs of disease before symptoms appear, assist in drug testing, optimize and personalize therapy, and assess the efficacy of treatment regimes for different types of cancer. Monte Carlo simulation packages are used as an important tool for the optimal design of detector systems. In addition they have demonstrated potential to improve image quality and acquisition protocols. Many general purpose (MCNP, Geant4, etc) or dedicated codes (SimSET etc) have been developed aiming to provide accurate and fast results. Special emphasis will be given to GATE toolkit. The GATE code currently under development by the OpenGATE collaboration is the most accurate and promising code for performing realistic simulations. The purpose of this article is to introduce the non expert reader to the current status of MC simulations in nuclear medicine and briefly provide examples of current simulated systems, and present future challenges that include simulation of clinical studies and dosimetry applications.

  3. Nuclear Power Plant Concrete Structures

    SciTech Connect

    Basu, Prabir; Labbe, Pierre; Naus, Dan

    2013-01-01

    A nuclear power plant (NPP) involves complex engineering structures that are significant items of the structures, systems and components (SSC) important to the safe and reliable operation of the NPP. Concrete is the commonly used civil engineering construction material in the nuclear industry because of a number of advantageous properties. The NPP concrete structures underwent a great degree of evolution, since the commissioning of first NPP in early 1960. The increasing concern with time related to safety of the public and environment, and degradation of concrete structures due to ageing related phenomena are the driving forces for such evolution. The concrete technology underwent rapid development with the advent of chemical admixtures of plasticizer/super plasticizer category as well as viscosity modifiers and mineral admixtures like fly ash and silica fume. Application of high performance concrete (HPC) developed with chemical and mineral admixtures has been witnessed in the construction of NPP structures. Along with the beneficial effect, the use of admixtures in concrete has posed a number of challenges as well in design and construction. This along with the prospect of continuing operation beyond design life, especially after 60 years, the impact of extreme natural events ( as in the case of Fukushima NPP accident) and human induced events (e.g. commercial aircraft crash like the event of September 11th 2001) has led to further development in the area of NPP concrete structures. The present paper aims at providing an account of evolution of NPP concrete structures in last two decades by summarizing the development in the areas of concrete technology, design methodology and construction techniques, maintenance and ageing management of concrete structures.

  4. Simulating Nuclear and Electronic Quantum Effects in Enzymes.

    PubMed

    Wang, L; Isborn, C M; Markland, T E

    2016-01-01

    An accurate treatment of the structures and dynamics that lead to enhanced chemical reactivity in enzymes requires explicit treatment of both electronic and nuclear quantum effects. The former can be captured in ab initio molecular dynamics (AIMD) simulations, while the latter can be included by performing ab initio path integral molecular dynamics (AI-PIMD) simulations. Both AIMD and AI-PIMD simulations have traditionally been computationally prohibitive for large enzymatic systems. Recent developments in streaming computer architectures and new algorithms to accelerate path integral simulations now make these simulations practical for biological systems, allowing elucidation of enzymatic reactions in unprecedented detail. In this chapter, we summarize these recent developments and discuss practical considerations for applying AIMD and AI-PIMD simulations to enzymes. PMID:27498646

  5. Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    NASA Technical Reports Server (NTRS)

    Emrich, William J., Jr.

    2008-01-01

    To support the eventual development of a nuclear thermal rocket engine, a state-of-the-art experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The test device simulates 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 as to accurately reproduce the temperatures and heat fluxes normally expected to occur as a result of nuclear fission while at the same time being exposed to flowing hydrogen. This project is referred to as the Nuclear Thermal Rocket Element Environment Simulator or NTREES. The NTREES device is located at the Marshall Space flight Center in a laboratory which has been modified to accommodate the high powers required to heat the test articles to the required temperatures and to handle the gaseous hydrogen flow required for the tests. Other modifications to the laboratory include the installation of a nitrogen gas supply system and a cooling water supply system. During the design and construction of the facility, every effort was made to comply with all pertinent regulations to provide assurance that the facility could be operated in a safe and efficient manner. The NTREES system can currently supply up to 50 kW of inductive heating to the fuel test articles, although the facility has been sized to eventually allow test article heating levels of up to several megawatts.

  6. Hydrodynamical Simulations of Nuclear Rings in Barred Galaxies

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Shen, Juntai; Kim, Woong-Tae

    2015-08-01

    Dust lanes, nuclear rings, and nuclear spirals are typical gas structures in the inner region of barred galaxies. Their shapes and properties are linked to the physical parameters of the host galaxy. We use high-resolution hydrodynamical simulations to study 2D gas flows in simple barred galaxy models. The nuclear rings formed in our simulations can be divided into two groups: one group is nearly round and the other is highly elongated. We find that roundish rings may not form when the bar pattern speed is too high or the bulge central density is too low. We also study the periodic orbits in our galaxy models, and find that the concept of inner Lindblad resonance (ILR) may be generalized by the extent of x2 orbits. All roundish nuclear rings in our simulations settle in the range of x2 orbits (or ILRs). However, knowing the resonances is insufficient to pin down the exact location of these nuclear rings. We suggest that the backbone of round nuclear rings is the x2 orbital family, i.e. round nuclear rings are allowed only in the radial range of x2 orbits. A round nuclear ring forms exactly at the radius where the residual angular momentum of infalling gas balances the centrifugal force, which can be described by a parameter f_ring measured from the rotation curve. We find an empirical relation between the bar parameters and f_ring, and apply it to measure bar pattern speed in a sample of barred galaxies with nuclear rings.

  7. Hydrodynamical Simulations of Nuclear Rings in Barred Galaxies

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Shen, Juntai; Kim, Woong-Tae

    2015-06-01

    Dust lanes, nuclear rings, and nuclear spirals are typical gas structures in the inner region of barred galaxies. Their shapes and properties are linked to the physical parameters of the host galaxy. We use high-resolution hydrodynamical simulations to study 2D gas flows in simple barred galaxy models. The nuclear rings formed in our simulations can be divided into two groups: one group is nearly round and the other is highly elongated. We find that roundish rings may not form when the bar pattern speed is too high or the bulge central density is too low. We also study the periodic orbits in our galaxy models, and find that the concept of inner Lindblad resonance (ILR) may be generalized by the extent of {x}2 orbits. All roundish nuclear rings in our simulations settle in the range of {x}2 orbits (or ILRs). However, knowing the resonances is insufficient to pin down the exact location of these nuclear rings. We suggest that the backbone of round nuclear rings is the {x}2 orbital family, i.e., round nuclear rings are allowed only in the radial range of {x}2 orbits. A round nuclear ring forms exactly at the radius where the residual angular momentum of infalling gas balances the centrifugal force, which can be described by a parameter {f}{ring} measured from the rotation curve. The gravitational torque on gas in high pattern speed models is larger, leading to a smaller ring size than in the low pattern speed models. Our result may have important implications for using nuclear rings to measure the parameters of real barred galaxies with 2D gas kinematics.

  8. Simulation of a marine nuclear reactor

    SciTech Connect

    Kusunoki, Tsuyoshi; Kyouya, Masahiko; Kobayashi, Hideo; Ochiai, Masaaki

    1995-02-01

    A Nuclear-powered ship Engineering Simulation SYstem (NESSY) has been developed by the Japan Atomic Energy Research Institute as an advanced design tool for research and development of future marine reactors. A marine reactor must respond to changing loads and to the ship`s motions because of the ship`s maneuvering and its presence in a marine environment. The NESSY has combined programs for the reactor plant behavior calculations and the ship`s motion calculations. Thus, it can simulate reactor power fluctuations caused by changing loads and the ship`s motions. It can also simulate the behavior of water in the pressurizer and steam generators. This water sloshes in response to the ship`s motions. The performance of NESSY has been verified by comparing the simulation calculations with the measured data obtained by experiments performed using the nuclear ship Mutsu. The effects of changing loads and the ship`s motions on the reactor behavior can be accurately simulated by NESSY.

  9. Simulation and evaluation of nuclear reaction spectra

    NASA Astrophysics Data System (ADS)

    Vizkelethy, G.

    1990-01-01

    A RUMP-like-[1] computer code was written for PCs in order to simulate and evaluate nuclear reaction spectra. The code was written in Turbo Pascal. Any particle-target combination can be used; the stopping power calculation based on the ZBL algorithm [2] and the cross sections are taken from experimental data. The effects of straggling and geometrical spread are included in the simulation. Examples are given for the 16O(d,P) 17O, 18O(P,α) 15N, 16O( 3He,α) 15O and 16O(α,α) 16O reactions and for ERDA measurements.

  10. NUCLEAR DATA RESOURCES FOR ADVANCED ANALYSIS AND SIMULATION.

    SciTech Connect

    PRITYCHENKO, B.

    2006-06-05

    The mission of the National Nuclear Data Center (NNDC) includes collection, evaluation, and dissemination of nuclear physics data for basic nuclear research and applied nuclear technologies. In 2004, to answer the needs of nuclear data users, NNDC completed a project to modernize storage and management of its databases and began offering new nuclear data Web services. Examples of nuclear reaction, nuclear structure and decay database applications along with a number of nuclear science codes are also presented.

  11. Effect of Coulomb screening length on nuclear "pasta" simulations

    NASA Astrophysics Data System (ADS)

    Alcain, P. N.; Giménez Molinelli, P. A.; Nichols, J. I.; Dorso, C. O.

    2014-05-01

    We study the role of the effective Coulomb interaction strength and length on the dynamics of nucleons in conditions according to those in a neutron star's crust. Calculations were made with a semiclassical molecular dynamics model, studying isospin symmetric matter at subsaturation densities and low temperatures. The electrostatic interaction between protons is included as a screened Coulomb potential in the spirit of the Thomas-Fermi approximation, but the screening length is artificially varied to explore its effect on the formation of the nonhomogeneous nuclear structures known as "nuclear pasta." As the screening length increases, we can see a transition from a one-per-cell pasta regime (due exclusively to finite-size effects) to a more appealing multiple pasta per simulation box. This qualitative difference in the structure of neutron star matter at low temperatures shows that special caution should be taken when the screening length is estimated for numerical simulations.

  12. Computer simulation of underwater nuclear events

    SciTech Connect

    Kamegai, M.

    1986-09-01

    This report describes the computer simulation of two underwater nuclear explosions, Operation Wigwam and a modern hypothetical explosion of greater yield. The computer simulations were done in spherical geometry with the LASNEX computer code. Comparison of the LASNEX calculation with Snay's analytical results and the Wigwam measurements shows that agreement in the shock pressure versus range in water is better than 5%. The results of the calculations are also consistent with the cube root scaling law for an underwater blast wave. The time constant of the wave front was determined from the wave profiles taken at several points. The LASNEX time-constant calculation and Snay's theoretical results agree to within 20%. A time-constant-versus-range relation empirically fitted by Snay is valid only within a limited range at low pressures, whereas a time-constant formula based on Sedov's similarity solution holds at very high pressures. This leaves the intermediate pressure range with neither an empirical nor a theoretical formula for the time constant. These one-dimensional simulations demonstrate applicability of the computer code to investigations of this nature, and justify the use of this technique for more complex two-dimensional problems, namely, surface effects on underwater nuclear explosions. 16 refs., 8 figs., 2 tabs.

  13. Soundtracks to Accompany Visualizations of Nuclear Pasta Simulations

    NASA Astrophysics Data System (ADS)

    Clark, Emily

    2014-09-01

    Nuclear pasta is a substance found in neutron stars and core-collapse supernovae, arising at the extreme densities near nuclear saturation, when the attractive nuclear and repulsive coulomb forces mold the dense sea of protons and neutrons into shapes such as spheres, tubes, and slabs, which somewhat resemble different types of pasta. The structures are analyzed using molecular dynamical simulations for different proton fractions, temperatures, densities, and number of nucleons. The system is stressed by stretching it, squeezing it, or subjecting it to some outside force. In order to obtain a more complete representation of how the nuclear pasta responds, sound tracks were produced to accompany videos of stretching simulations. The audio tracks were made by assuming sound waves are produced from changes in the nucleon density. This density was calculated within a small region at frequent time intervals during the run. The resulting sound track was then synced with a video of the run in order to emphasize the development of the system as the pasta moves and breaks. Nuclear pasta is a substance found in neutron stars and core-collapse supernovae, arising at the extreme densities near nuclear saturation, when the attractive nuclear and repulsive coulomb forces mold the dense sea of protons and neutrons into shapes such as spheres, tubes, and slabs, which somewhat resemble different types of pasta. The structures are analyzed using molecular dynamical simulations for different proton fractions, temperatures, densities, and number of nucleons. The system is stressed by stretching it, squeezing it, or subjecting it to some outside force. In order to obtain a more complete representation of how the nuclear pasta responds, sound tracks were produced to accompany videos of stretching simulations. The audio tracks were made by assuming sound waves are produced from changes in the nucleon density. This density was calculated within a small region at frequent time intervals

  14. Nuclear Structure in China 2010

    NASA Astrophysics Data System (ADS)

    Bai, Hong-Bo; Meng, Jie; Zhao, En-Guang; Zhou, Shan-Gui

    2011-08-01

    Personal view on nuclear physics research / Jie Meng -- High-spin level structures in [symbol]Zr / X. P. Cao ... [et al.] -- Constraining the symmetry energy from the neutron skin thickness of tin isotopes / Lie-Wen Chen ... [et al.] -- Wobbling rotation in atomic nuclei / Y. S. Chen and Zao-Chun Gao -- The mixing of scalar mesons and the possible nonstrange dibaryons / L. R. Dai ... [et al.] -- Net baryon productions and gluon saturation in the SPS, RHIC and LHC energy regions / Sheng-Qin Feng -- Production of heavy isotopes with collisions between two actinide nuclides / Z. Q. Feng ... [et al.] -- The projected configuration interaction method / Zao-Chun Gao and Yong-Shou Chen -- Applications of Nilsson mean-field plus extended pairing model to rare-earth nuclei / Xin Guan ... [et al.] -- Complex scaling method and the resonant states / Jian-You Guo ... [et al.] -- Probing the equation of state by deep sub-barrier fusion reactions / Hong-Jun Hao and Jun-Long Tian -- Doublet structure study in A[symbol]105 mass region / C. Y. He ... [et al.] -- Rotational bands in transfermium nuclei / X. T. He -- Shape coexistence and shape evolution [symbol]Yb / H. Hua ... [et al.] -- Multistep shell model method in the complex energy plane / R. J. Liotta -- The evolution of protoneutron stars with kaon condensate / Ang Li -- High spin structures in the [symbol]Lu nucleus / Li Cong-Bo ... [et al.] -- Nuclear stopping and equation of state / QingFeng Li and Ying Yuan -- Covariant description of the low-lying states in neutron-deficient Kr isotopes / Z. X. Li ... [et al.] -- Isospin corrections for superallowed [symbol] transitions / HaoZhao Liang ... [et al.] -- The positive-parity band structures in [symbol]Ag / C. Liu ... [et al.] -- New band structures in odd-odd [symbol]I and [symbol]I / Liu GongYe ... [et al.] -- The sd-pair shell model and interacting boson model / Yan-An Luo ... [et al.] -- Cross-section distributions of fragments in the calcium isotopes projectile

  15. Nuclear Structure in China 2010

    NASA Astrophysics Data System (ADS)

    Bai, Hong-Bo; Meng, Jie; Zhao, En-Guang; Zhou, Shan-Gui

    2011-08-01

    Personal view on nuclear physics research / Jie Meng -- High-spin level structures in [symbol]Zr / X. P. Cao ... [et al.] -- Constraining the symmetry energy from the neutron skin thickness of tin isotopes / Lie-Wen Chen ... [et al.] -- Wobbling rotation in atomic nuclei / Y. S. Chen and Zao-Chun Gao -- The mixing of scalar mesons and the possible nonstrange dibaryons / L. R. Dai ... [et al.] -- Net baryon productions and gluon saturation in the SPS, RHIC and LHC energy regions / Sheng-Qin Feng -- Production of heavy isotopes with collisions between two actinide nuclides / Z. Q. Feng ... [et al.] -- The projected configuration interaction method / Zao-Chun Gao and Yong-Shou Chen -- Applications of Nilsson mean-field plus extended pairing model to rare-earth nuclei / Xin Guan ... [et al.] -- Complex scaling method and the resonant states / Jian-You Guo ... [et al.] -- Probing the equation of state by deep sub-barrier fusion reactions / Hong-Jun Hao and Jun-Long Tian -- Doublet structure study in A[symbol]105 mass region / C. Y. He ... [et al.] -- Rotational bands in transfermium nuclei / X. T. He -- Shape coexistence and shape evolution [symbol]Yb / H. Hua ... [et al.] -- Multistep shell model method in the complex energy plane / R. J. Liotta -- The evolution of protoneutron stars with kaon condensate / Ang Li -- High spin structures in the [symbol]Lu nucleus / Li Cong-Bo ... [et al.] -- Nuclear stopping and equation of state / QingFeng Li and Ying Yuan -- Covariant description of the low-lying states in neutron-deficient Kr isotopes / Z. X. Li ... [et al.] -- Isospin corrections for superallowed [symbol] transitions / HaoZhao Liang ... [et al.] -- The positive-parity band structures in [symbol]Ag / C. Liu ... [et al.] -- New band structures in odd-odd [symbol]I and [symbol]I / Liu GongYe ... [et al.] -- The sd-pair shell model and interacting boson model / Yan-An Luo ... [et al.] -- Cross-section distributions of fragments in the calcium isotopes projectile

  16. Computer simulation of underwater nuclear effects

    SciTech Connect

    Kamegai, M.

    1987-01-30

    We investigated underwater nuclear effects by computer simulations. First, we computed a long distance wave propagation in water by the 1-D LASNEX code by modeling the energy source and the underwater environment. The pressure-distance data were calculated for two quite different yields; pressures range from 300 GPa to 15 MPa. They were found to be in good agreement with Snay's theoretical points and the Wigwam measurements. The computed data also agree with the similarity solution at high pressures and the empirical equation at low pressures. After completion of the 1-D study, we investigated a free surface effect commonly referred to as irregular surface rarefaction by applying two hydrocodes (LASNEX and ALE), linked at the appropriate time. Using these codes, we simulated near-surface explosions for three depths of burst (3 m, 21 m and 66.5 m), which represent the strong, intermediate, and weak surface shocks, respectively.

  17. Modeling and Simulation of a Nuclear Fuel Element Test Section

    NASA Technical Reports Server (NTRS)

    Moran, Robert P.; Emrich, William

    2011-01-01

    "The Nuclear Thermal Rocket Element Environmental Simulator" test section closely simulates the internal operating conditions of a thermal nuclear rocket. The purpose of testing is to determine the ideal fuel rod characteristics for optimum thermal heat transfer to their hydrogen cooling/working fluid while still maintaining fuel rod structural integrity. Working fluid exhaust temperatures of up to 5,000 degrees Fahrenheit can be encountered. The exhaust gas is rendered inert and massively reduced in temperature for analysis using a combination of water cooling channels and cool N2 gas injectors in the H2-N2 mixer portion of the test section. An extensive thermal fluid analysis was performed in support of the engineering design of the H2-N2 mixer in order to determine the maximum "mass flow rate"-"operating temperature" curve of the fuel elements hydrogen exhaust gas based on the test facilities available cooling N2 mass flow rate as the limiting factor.

  18. Nuclear Structure Data for the Present Age

    NASA Astrophysics Data System (ADS)

    Baglin, Coral M.

    2005-05-01

    The US Nuclear Data Program maintains and provides easy and free access to several comprehensive databases that assist scientists to sift through and assess the vast quantity of published nuclear structure and decay data. These databases are an invaluable asset for nuclear-science experimentalists and theorists alike, and the recommended values provided for nuclear properties such as decay modes, level energies and lifetimes, and radiation properties can also be of great importance to specialists in other fields such as medicine, geophysics, and reactor design. The Evaluated Nuclear Structure Data File (ENSDF) contains experimental nuclear structure data for all known nuclides, evaluated by the US nuclear data program evaluators in collaboration with a number of international data groups; the Nuclear Science Reference (NSR) database provides complementary bibliographic information; the Experimental Unevaluated Nuclear Data Listing (XUNDL) exists to enable rapid access to experimental nuclear-structure data compiled from the most recent publications (primarily in high-spin physics). This paper presents an overview of the nuclear structure and decay data available through these databases, with emphasis on recent and forthcoming additions to and presentations of the available material.

  19. Theoretical studies in nuclear reactions and nuclear structure

    SciTech Connect

    Not Available

    1992-05-01

    Research in the Maryland Nuclear Theory Group focusses on problems in four basic areas of current relevance. Hadrons in nuclear matter; the structure of hadrons; relativistic nuclear physics and heavy ion dynamics and related processes. The section on hadrons in nuclear matter groups together research items which are aimed at exploring ways in which the properties of nucleons and the mesons which play a role in the nuclear force are modified in the nuclear medium. A very interesting result has been the finding that QCD sum rules supply a new insight into the decrease of the nucleon's mass in the nuclear medium. The quark condensate, which characterizes spontaneous chiral symmetry breaking of the late QCD vacuum, decreases in nuclear matter and this is responsible for the decrease of the nucleon's mass. The section on the structure of hadrons contains progress reports on our research aimed at understanding the structure of the nucleon. Widely different approaches are being studied, e.g., lattice gauge calculations, QCD sum rules, quark-meson models with confinement and other hedgehog models. A major goal of this type of research is to develop appropriate links between nuclear physics and QCD. The section on relativistic nuclear physics represents our continuing interest in developing an appropriate relativistic framework for nuclear dynamics. A Lorentz-invariant description of the nuclear force suggests a similar decrease of the nucleon's mass in the nuclear medium as has been found from QCD sum rules. Work in progress extends previous successes in elastic scattering to inelastic scattering of protons by nuclei. The section on heavy ion dynamics and related processes reports on research into the e{sup +}e{sup {minus}} problem and heavy ion dynamics.

  20. Theoretical studies in nuclear reactions and nuclear structure. Progress report

    SciTech Connect

    Not Available

    1992-05-01

    Research in the Maryland Nuclear Theory Group focusses on problems in four basic areas of current relevance. Hadrons in nuclear matter; the structure of hadrons; relativistic nuclear physics and heavy ion dynamics and related processes. The section on hadrons in nuclear matter groups together research items which are aimed at exploring ways in which the properties of nucleons and the mesons which play a role in the nuclear force are modified in the nuclear medium. A very interesting result has been the finding that QCD sum rules supply a new insight into the decrease of the nucleon`s mass in the nuclear medium. The quark condensate, which characterizes spontaneous chiral symmetry breaking of the late QCD vacuum, decreases in nuclear matter and this is responsible for the decrease of the nucleon`s mass. The section on the structure of hadrons contains progress reports on our research aimed at understanding the structure of the nucleon. Widely different approaches are being studied, e.g., lattice gauge calculations, QCD sum rules, quark-meson models with confinement and other hedgehog models. A major goal of this type of research is to develop appropriate links between nuclear physics and QCD. The section on relativistic nuclear physics represents our continuing interest in developing an appropriate relativistic framework for nuclear dynamics. A Lorentz-invariant description of the nuclear force suggests a similar decrease of the nucleon`s mass in the nuclear medium as has been found from QCD sum rules. Work in progress extends previous successes in elastic scattering to inelastic scattering of protons by nuclei. The section on heavy ion dynamics and related processes reports on research into the e{sup +}e{sup {minus}} problem and heavy ion dynamics.

  1. Nuclear structure studies with intermediate energy probes

    SciTech Connect

    Lee, T.S.H.

    1993-10-01

    Nuclear structure studies with pions are reviewed. Results from a recent study of 1 p-shell nuclei using (e,e{prime}), ({pi}, {pi}{prime}), and ({gamma},{pi}) reactions are reported. Future nuclear structure studies with GeV electrons at CEBAF are also briefly discussed.

  2. Nuclear structure, gene expression and development.

    PubMed

    Brown, K

    1999-01-01

    This article considers the extent to which features of nuclear structure are involved in the regulation of genome function. The recent renaissance in imaging technology has inspired a new determination to assign specific functions to nuclear domains or structures, many of which have been described as "factories" to express the idea that they coordinate nuclear processes in an efficient way. Visual data have been combined with genetic and biochemical information to support the idea that nuclear organization has functional significance. Particular DNA sequences or chromatin structures may nucleate domains that are permissive or restrictive of transcription, to which active or inactive loci could be recruited. Associations within the nucleus, as well as many nuclear structures, are transient and change dynamically during cell cycle progression and development. Despite this complexity, elucidation of the possible structural basis of epigenetic phenomena, such as the inheritance of a "cellular memory" of gene expression status, is an important goal for cell biology. Topics for discussion include the regulatory effect of chromatin structure on gene expression, putative "nuclear addresses" for genes and proteins, the functional significance of nuclear bodies, and the role of the nuclear matrix in nuclear compartmentalization. PMID:10651237

  3. Adaptive Sampling Algorithms for Probabilistic Risk Assessment of Nuclear Simulations

    SciTech Connect

    Diego Mandelli; Dan Maljovec; Bei Wang; Valerio Pascucci; Peer-Timo Bremer

    2013-09-01

    Nuclear simulations are often computationally expensive, time-consuming, and high-dimensional with respect to the number of input parameters. Thus exploring the space of all possible simulation outcomes is infeasible using finite computing resources. During simulation-based probabilistic risk analysis, it is important to discover the relationship between a potentially large number of input parameters and the output of a simulation using as few simulation trials as possible. This is a typical context for performing adaptive sampling where a few observations are obtained from the simulation, a surrogate model is built to represent the simulation space, and new samples are selected based on the model constructed. The surrogate model is then updated based on the simulation results of the sampled points. In this way, we attempt to gain the most information possible with a small number of carefully selected sampled points, limiting the number of expensive trials needed to understand features of the simulation space. We analyze the specific use case of identifying the limit surface, i.e., the boundaries in the simulation space between system failure and system success. In this study, we explore several techniques for adaptively sampling the parameter space in order to reconstruct the limit surface. We focus on several adaptive sampling schemes. First, we seek to learn a global model of the entire simulation space using prediction models or neighborhood graphs and extract the limit surface as an iso-surface of the global model. Second, we estimate the limit surface by sampling in the neighborhood of the current estimate based on topological segmentations obtained locally. Our techniques draw inspirations from topological structure known as the Morse-Smale complex. We highlight the advantages and disadvantages of using a global prediction model versus local topological view of the simulation space, comparing several different strategies for adaptive sampling in both

  4. Electric heater for nuclear fuel rod simulators

    DOEpatents

    McCulloch, Reginald W.; Morgan, Jr., Chester S.; Dial, Ralph E.

    1982-01-01

    The present invention is directed to an electric cartridge-type heater for use as a simulator for a nuclear fuel pin in reactor studies. The heater comprises an elongated cylindrical housing containing a longitudinally extending helically wound heating element with the heating element radially inwardly separated from the housing. Crushed cold-pressed preforms of boron nitride electrically insulate the heating element from the housing while providing good thermal conductivity. Crushed cold-pressed preforms of magnesia or a magnesia-15 percent boron nitride mixture are disposed in the cavity of the helical heating element. The coefficient of thermal expansion of the magnesia or the magnesia-boron nitride mixture is higher than that of the boron nitride disposed about the heating element for urging the boron nitride radially outwardly against the housing during elevated temperatures to assure adequate thermal contact between the housing and the boron nitride.

  5. Nuclear Thermal Rocket Simulation in NPSS

    NASA Technical Reports Server (NTRS)

    Belair, Michael L.; Sarmiento, Charles J.; Lavelle, Thomas L.

    2013-01-01

    Four nuclear thermal rocket (NTR) models have been created in the Numerical Propulsion System Simulation (NPSS) framework. The models are divided into two categories. One set is based upon the ZrC-graphite composite fuel element and tie tube-style reactor developed during the Nuclear Engine for Rocket Vehicle Application (NERVA) project in the late 1960s and early 1970s. The other reactor set is based upon a W-UO2 ceramic- metallic (CERMET) fuel element. Within each category, a small and a large thrust engine are modeled. The small engine models utilize RL-10 turbomachinery performance maps and have a thrust of approximately 33.4 kN (7,500 lbf ). The large engine models utilize scaled RL-60 turbomachinery performance maps and have a thrust of approximately 111.2 kN (25,000 lbf ). Power deposition profiles for each reactor were obtained from a detailed Monte Carlo N-Particle (MCNP5) model of the reactor cores. Performance factors such as thermodynamic state points, thrust, specific impulse, reactor power level, and maximum fuel temperature are analyzed for each engine design.

  6. Nuclear Thermal Rocket Simulation in NPSS

    NASA Technical Reports Server (NTRS)

    Belair, Michael L.; Sarmiento, Charles J.; Lavelle, Thomas M.

    2013-01-01

    Four nuclear thermal rocket (NTR) models have been created in the Numerical Propulsion System Simulation (NPSS) framework. The models are divided into two categories. One set is based upon the ZrC-graphite composite fuel element and tie tube-style reactor developed during the Nuclear Engine for Rocket Vehicle Application (NERVA) project in the late 1960s and early 1970s. The other reactor set is based upon a W-UO2 ceramic-metallic (CERMET) fuel element. Within each category, a small and a large thrust engine are modeled. The small engine models utilize RL-10 turbomachinery performance maps and have a thrust of approximately 33.4 kN (7,500 lbf ). The large engine models utilize scaled RL-60 turbomachinery performance maps and have a thrust of approximately 111.2 kN (25,000 lbf ). Power deposition profiles for each reactor were obtained from a detailed Monte Carlo N-Particle (MCNP5) model of the reactor cores. Performance factors such as thermodynamic state points, thrust, specific impulse, reactor power level, and maximum fuel temperature are analyzed for each engine design.

  7. Aerosol simulation including chemical and nuclear reactions

    SciTech Connect

    Marwil, E.S.; Lemmon, E.C.

    1985-01-01

    The numerical simulation of aerosol transport, including the effects of chemical and nuclear reactions presents a challenging dynamic accounting problem. Particles of different sizes agglomerate and settle out due to various mechanisms, such as diffusion, diffusiophoresis, thermophoresis, gravitational settling, turbulent acceleration, and centrifugal acceleration. Particles also change size, due to the condensation and evaporation of materials on the particle. Heterogeneous chemical reactions occur at the interface between a particle and the suspending medium, or a surface and the gas in the aerosol. Homogeneous chemical reactions occur within the aersol suspending medium, within a particle, and on a surface. These reactions may include a phase change. Nuclear reactions occur in all locations. These spontaneous transmutations from one element form to another occur at greatly varying rates and may result in phase or chemical changes which complicate the accounting process. This paper presents an approach for inclusion of these effects on the transport of aerosols. The accounting system is very complex and results in a large set of stiff ordinary differential equations (ODEs). The techniques for numerical solution of these ODEs require special attention to achieve their solution in an efficient and affordable manner. 4 refs.

  8. Multi-physics nuclear reactor simulator for advanced nuclear engineering education

    SciTech Connect

    Yamamoto, A.

    2012-07-01

    Multi-physics nuclear reactor simulator, which aims to utilize for advanced nuclear engineering education, is being introduced to Nagoya Univ.. The simulator consists of the 'macroscopic' physics simulator and the 'microscopic' physics simulator. The former performs real time simulation of a whole nuclear power plant. The latter is responsible to more detail numerical simulations based on the sophisticated and precise numerical models, while taking into account the plant conditions obtained in the macroscopic physics simulator. Steady-state and kinetics core analyses, fuel mechanical analysis, fluid dynamics analysis, and sub-channel analysis can be carried out in the microscopic physics simulator. Simulation calculations are carried out through dedicated graphical user interface and the simulation results, i.e., spatial and temporal behaviors of major plant parameters are graphically shown. The simulator will provide a bridge between the 'theories' studied with textbooks and the 'physical behaviors' of actual nuclear power plants. (authors)

  9. Global nuclear-structure calculations

    SciTech Connect

    Moeller, P.; Nix, J.R.

    1990-04-20

    The revival of interest in nuclear ground-state octupole deformations that occurred in the 1980's was stimulated by observations in 1980 of particularly large deviations between calculated and experimental masses in the Ra region, in a global calculation of nuclear ground-state masses. By minimizing the total potential energy with respect to octupole shape degrees of freedom in addition to {epsilon}{sub 2} and {epsilon}{sub 4} used originally, a vastly improved agreement between calculated and experimental masses was obtained. To study the global behavior and interrelationships between other nuclear properties, we calculate nuclear ground-state masses, spins, pairing gaps and {Beta}-decay and half-lives and compare the results to experimental qualities. The calculations are based on the macroscopic-microscopic approach, with the microscopic contributions calculated in a folded-Yukawa single-particle potential.

  10. Determination of the three-dimensional solution structure of the antihypertensive and antiviral protein BDS-I from the sea anemone Anemonia sulcata: A study using nuclear magnetic resonance and hybrid distance geometry-dynamical simulated annealing

    SciTech Connect

    Driscoll, P.C.; Gronenborn, A.M.; Beress, L.; Clore, G.M. )

    1989-03-07

    The three-dimensional solution structure of the antihypertensive and antiviral protein BDS-I from the sea anemone Anemonia sulcata has been determined on the basis of 489 interproton and 24 hydrogen-bonding distance restraints supplemented by 23 {phi} backbone and 21 {sub {chi}1} side-chain torsion angle restraints derived from nuclear magnetic resonance (NMR) measurements. A total of 42 structures is calculated by a hybrid metric matrix distance geometry-dynamical simulated annealing approach. Both the backbone and side-chain atom positions are well defined. The average atomic rms difference between the 42 individual SA structures and the mean structure obtained by averaging their coordinates is 0.67 {plus minus} 0.12 {angstrom} for the backbone atoms and 0.90 {plus minus} 0.17 {angstrom} for all atoms. The core of the protein is formed by a triple-stranded antiparallel {beta}-sheet composed of residues 14-16 (strand 1), 30-34 (strand 2), and 37-41 (strand 3) with an additional mini-antiparallel {beta}-sheet at the N-terminus (residues 6-9). The first and second strands of the triple-stranded antiparallel {beta}-sheet are connected by a long exposed loop. A number of side-chain interactions are discussed in light of the structure.

  11. The AMEDEE Nuclear Structure Database

    SciTech Connect

    Hilaire, S.; Girod, M.

    2008-05-12

    The increasing need for nuclear data far from the valley of stability requires information on nuclei which cannot be accessed experimentally or for which almost no experimental data is known. Consequently, the use of microscopic approaches to predict properties of such poorly known nuclei is necessary as a first step to improve our understanding of nuclear reaction on exotic nuclei. Within this context, large scale axial mean field calculations from proton to neutron drip-lines have been performed using the Hartree-Fock-Bogoliubov method based on the DIS Gogny nucleon-nucleon effective interaction. Nearly 7000 nuclei have been studied under the axial symmetry hypothesis and several properties are now available for the nuclear scientific community on an Internet web site for every individual nucleus.

  12. Complete event simulations of nuclear fission

    NASA Astrophysics Data System (ADS)

    Vogt, Ramona

    2015-10-01

    For many years, the state of the art for treating fission in radiation transport codes has involved sampling from average distributions. In these average fission models energy is not explicitly conserved and everything is uncorrelated because all particles are emitted independently. However, in a true fission event, the energies, momenta and multiplicities of the emitted particles are correlated. Such correlations are interesting for many modern applications. Event-by-event generation of complete fission events makes it possible to retain the kinematic information for all particles emitted: the fission products as well as prompt neutrons and photons. It is therefore possible to extract any desired correlation observables. Complete event simulations can be included in general Monte Carlo transport codes. We describe the general functionality of currently available fission event generators and compare results for several important observables. This work was performed under the auspices of the US DOE by LLNL, Contract DE-AC52-07NA27344. We acknowledge support of the Office of Defense Nuclear Nonproliferation Research and Development in DOE/NNSA.

  13. NASTRAN Analysis Comparison to Shock Tube Tests Used to Simulate Nuclear Overpressures

    NASA Technical Reports Server (NTRS)

    Wheless, T. K.

    1985-01-01

    This report presents a study of the effectiveness of the NASTRAN computer code for predicting structural response to nuclear blast overpressures. NASTRAN's effectiveness is determined by comparing results against shock tube tests used to simulate nuclear overpressures. Seven panels of various configurations are compared in this study. Panel deflections are the criteria used to measure NASTRAN's effectiveness. This study is a result of needed improvements in the survivability/vulnerability analyses subjected to nuclear blast.

  14. Laser spectroscopy for nuclear structure physics

    NASA Astrophysics Data System (ADS)

    Campbell, P.; Moore, I. D.; Pearson, M. R.

    2016-01-01

    High-resolution laser spectroscopy is an established powerful tool in the study of nuclear shape, size and multipole moments. Measurements of the hyperfine structures and isotope shifts in the atomic spectra of radioactive nuclei provide unique insight into the evolution of the nuclear macroscopic shape and microscopic structure. These measurements can be made with high precision and high sensitivity and applied directly on-line at radioactive nuclear beam facilities. Recent measurements, advances at facilities and the future direction of the field are reviewed. A summary of experimental data is presented.

  15. Rotation and shape changes in {sup 151}Tb and {sup 196}Pb: Probes of nuclear structure and tunneling process in warm nuclei. II. Microscopic Monte Carlo simulation

    SciTech Connect

    Leoni, S.; Bracco, A.; Camera, F.; Corsi, A.; Crespi, F. C. L.; Montanari, D.; Pignanelli, M.; Benzoni, G.; Blasi, N.; Million, B.; Vigezzi, E.; Wieland, O.; Mason, P.; Matsuo, M.; Shimizu, Y. R.; Curien, D.; Duchene, G.; Robin, J.; Bednarczyk, P.; Kmiecik, M.

    2009-06-15

    A Monte Carlo simulation of the {gamma} decay of superdeformed nuclei has been developed. It is based on microscopic calculations for the energy levels, E2 decay probabilities, collective mass parameters, and potential energy barriers. The use of microscopically calculated quantities largely reduces the parameters of the simulation, allowing one to focus on the basic ingredients of the physical processes. Calculations are performed for the warm rotating superdeformed nuclei {sup 151}Tb and {sup 196}Pb, for which high statistics Euroball IV data are available. The dependence on the simulation parameters is investigated, together with the basic features of the microscopic calculations.

  16. Nuclear Structure of the Noble Gas

    NASA Astrophysics Data System (ADS)

    Seong, Nakyeong

    Modern physics usually pictures the nuclear structure as about sphere and treats various detailed situation as perturbative, which may be obscured. In addition, the explanation why 235U undergoes nuclear fission and 238U does not is too difficult and unclear for the people to understand. However, in this paper, we introduce a new approach on the nuclear structure of the noble gas, which simultaneously can explain several phenomena that is obscurely elucidated by modern physics. We consider a 1:1 ratio between protons and neutrons and need the concept of the symmetry of the nuclear structure, because the electron's shell of the noble gas is fully occupied. From these, we can predict the number of neutrons of each noble gas exactly

  17. Shell structure from nuclear observables

    NASA Astrophysics Data System (ADS)

    Bentley, I.; Rodríguez, Y. Colón; Cunningham, S.; Aprahamian, A.

    2016-04-01

    The appearance and disappearance of shells and subshells are determined using a previously introduced method of structural analysis. This work extends the approach and applies it to protons, in addition to neutrons, in an attempt to provide a more complete understanding of shell structure in nuclei. Experimental observables including the mean-square charge radius, as well as other spectroscopic and mass related quantities are analyzed for extrema. This analysis also uses differential observables among adjacent even-even nuclei to serve as the derivatives for these quantities of interest. Local extrema in these quantities indicate shell structure and the lack of local extrema indicate missing shell closures. The shell structure of low-mass nuclei is inconsistent likely as a consequence of the single-particle structure. Additionally, multiple shell features occurring in midshell regions are determined by combining information from two or more observables. Our results near stability complement previous observations further out.

  18. Probing Nuclear Structure with Fast Neutrons

    SciTech Connect

    Yates, Steven W.

    2009-01-28

    The advantages of using inelastic neutron scattering with detection of the emitted {gamma} rays, i.e., the (n,n'{gamma}) reaction, for exploring the structure of stable nuclei are reviewed. Examples of the information available with these techniques are provided and progress in understanding multiphonon excitations is described. The unique nuclear structure of {sup 94}Zr is discussed.

  19. NTP system simulation and detailed nuclear engine modeling

    NASA Technical Reports Server (NTRS)

    Anghaie, Samim

    1993-01-01

    The topics are presented in viewgraph form and include the following: nuclear thermal propulsion (NTP) & detailed nuclear engine modeling; modeling and engineering simulation of nuclear thermal rocket systems; nuclear thermal rocket simulation system; INSPI-NTVR core axial flow profiles; INSPI-NTRV core axial flow profiles; specific impulse vs. chamber pressure; turbine pressure ratio vs. chamber pressure; NERVA core axial flow profiles; P&W XNR2000 core axial flow profiles; pump pressure rise vs. chamber pressure; streamline of jet-induced flow in cylindrical chamber; flow pattern of a jet-induced flow in a chamber; and radiative heat transfer models.

  20. Simulation of the underwater nuclear explosion and its effects. Master's thesis

    SciTech Connect

    Miller, W.E.

    1992-06-01

    This research was conducted to enhance understanding of the use of high explosives to simulate the effects of a nuclear underwater explosion. A review of the known characteristics of the nuclear, spherical conventional, and tapered conventional underwater pressure-time histories illustrates the selection of the tapered charge to simulate the underwater nuclear explosion. Three areas of study were then pursued. The first compared the structural response resulting from attack by conventional and nuclear type pressure profiles, verifying the need to match duration as well as peak pressure when simulating the underwater nuclear explosion. The second employed finite element analysis to study the three dimensional shock generated by a tapered charge. Third, a computer program was written to couple an optimizer with an existing tapered charge pressure-profile generating code to improve the tapered charge design process.

  1. Nuclear versus nucleon structure effects on nuclear transparency

    SciTech Connect

    O. Benhar

    1997-06-25

    Nuclear structure effects account for the observed enhancement of the nuclear transparency to moderate energy protons, with respect to the predictions of Glauber theory. This enhancement appears to be comparable to the one associated with the onset of color transparency in the Q2 range spanned by the available (e,e'p) data (Q2 < 7 (GeV/c)2). It is argued that in this kinematical regime a stronger colour transparency signal can be observed in the low energy loss tail of the inclusive electron-nucleus cross section, corresponding to large values of the Bjorken scaling variable x (x>2).

  2. Theoretical nuclear structure. Progress report for 1997

    SciTech Connect

    Nazarewicz, W.; Strayer, M.R.

    1997-12-31

    This research effort is directed toward theoretical support and guidance for the fields of radioactive ion beam physics, gamma-ray spectroscopy, and the interface between nuclear structure and nuclear astrophysics. The authors report substantial progress in all these areas. One measure of progress is publications and invited material. The research described here has led to more than 25 papers that are published, accepted, or submitted to refereed journals, and to 25 invited presentations at conferences and workshops.

  3. Nuclear diffractive structure functions at high energies

    SciTech Connect

    Marquet,C.; Kowalski, H.; Lappi, T.; Venugopalan, R.

    2008-08-08

    A future high-energy electron-ion collider would explore the non-linear weakly-coupled regime of QCD, and test the Color Glass Condensate (CGC) approach to high-energy scattering. Hard diffraction in deep inelastic scattering off nuclei will provide many fundamental measurements. In this work, the nuclear diffractive structure function F{sub 2,A}{sup D} is predicted in the CGC framework, and the features of nuclear enhancement and suppression are discussed.

  4. Creep of Structural Nuclear Composites

    SciTech Connect

    Will Windes; R.W. Lloyd

    2005-09-01

    A research program has been established to investigate fiber reinforced ceramic composites to be used as control rod components within a Very High Temperature Reactor (VHTR) design. Two candidate systems have been identified, carbon fiber reinforced carbon (Cf/C) and silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites. One of the primary degradation mechanisms anticipated for these core components is high temperature thermal and irradiation enhanced creep. As a consequence, high temperature test equipment, testing methodologies, and test samples for very high temperature (up to 1600º C) tensile strength and long duration creep studies have been established. Actual testing of both tubular and flat, "dog-bone"-shaped tensile composite specimens will begin next year. Since there is no precedence for using ceramic composites within a nuclear reactor, ASTM standard test procedures are currently being established from these high temperature mechanical tests.

  5. Nuclear structure at intermediate energies

    SciTech Connect

    Bonner, B.E.; Mutchler, G.S.

    1991-09-30

    The theme that unites the sometimes seemingly disparate experiments undertaken by the Bonner Lab Medium Energy Group is a determination to understand in detail the many facets and manifestations of the strong interaction, that which is now referred to as nonperturbative QCD. Whether we are investigating the question of just what does carry the spin of baryons, or the extent of the validity of the SU(6) wavefunctions for the excited hyperons (as will be measured in their radiative decays in our CEBAF experiment), or questions associated with the formation of a new state of matter predicted by QCD (the subject of our BNL experiments E810, E854, as well as our approved experiment at RHIC), -- all these projects share this common goal. Our other experiments represent different approaches to the same broad undertaking. LAMPF E1097 will provide definitive answers to the question of the spin dependence of the inelastic channel of pion production in the n-p interaction. FNAL E683 may well open a new field of investigation in nuclear physics: that of just how quarks and gluons interact with nuclear matter as they transverse nuclei of different sizes. In most all of the experiments mentioned above, the Bonner Lab Group is playing major leadership roles as well as doing a big fraction of the hard work that such experiments require. We use many of the facilities that are unavailable to the intermediate energy physics community and we use our expertise to design and fabricate the detectors and instrumentation that are required to perform the measurements which we decide to do.

  6. A Study on Structured Simulation Framework for Design and Evaluation of Human-Machine Interface System -Application for On-line Risk Monitoring for PWR Nuclear Power Plant-

    SciTech Connect

    Zhan, J.; Yang, M.; Li, S.C.; Peng, M.J.; Yan, S.Y.; Zhang, Z.J.

    2006-07-01

    The operators in the main control room of Nuclear Power Plant (NPP) need to monitor plant condition through operation panels and understand the system problems by their experiences and skills. It is a very hard work because even a single fault will cause a large number of plant parameters abnormal and operators are required to perform trouble-shooting actions in a short time interval. It will bring potential risks if operators misunderstand the system problems or make a commission error to manipulate an irrelevant switch with their current operation. This study aims at developing an on-line risk monitoring technique based on Multilevel Flow Models (MFM) for monitoring and predicting potential risks in current plant condition by calculating plant reliability. The proposed technique can be also used for navigating operators by estimating the influence of their operations on plant condition before they take an action that will be necessary in plant operation, and therefore, can reduce human errors. This paper describes the risk monitoring technique and illustrates its application by a Steam Generator Tube Rupture (SGTR) accident in a 2-loop Pressurized Water Reactor (PWR) Marine Nuclear Power Plant (MNPP). (authors)

  7. Structured building model reduction toward parallel simulation

    SciTech Connect

    Dobbs, Justin R.; Hencey, Brondon M.

    2013-08-26

    Building energy model reduction exchanges accuracy for improved simulation speed by reducing the number of dynamical equations. Parallel computing aims to improve simulation times without loss of accuracy but is poorly utilized by contemporary simulators and is inherently limited by inter-processor communication. This paper bridges these disparate techniques to implement efficient parallel building thermal simulation. We begin with a survey of three structured reduction approaches that compares their performance to a leading unstructured method. We then use structured model reduction to find thermal clusters in the building energy model and allocate processing resources. Experimental results demonstrate faster simulation and low error without any interprocessor communication.

  8. Nuclear Structure Research at Richmond

    SciTech Connect

    Beausang, Cornelius W.

    2015-04-30

    The goals for the final year were; (1) to continue ongoing efforts to develop and enhance GRETINA and work towards GRETA; (2) to investigate the structure of non-yrast states in shape transitional Sm and Gd nuclei; (3) to investigate the structure of selected light Cd nuclei; (4) to exploit the surrogate reaction technique to extract (n,f) cross sections for actinide nuclei, particularly the first measurement of the 236Pu and 237Pu(n,f) cross sections.

  9. 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

  10. Electron Scattering and Nuclear Structure

    ERIC Educational Resources Information Center

    Trower, W. P.; Ficenec, J. R.

    1971-01-01

    Presents information about the nucleus gained by studies of electron scattering. Discusses what can be implied about the shape of the charge distribution, the nucleus positions, the vibrational modes of the nucleus, the momentum of the nucleus, and the granularity and core structures of the nucleus. (DS)

  11. Ab initio nuclear structure theory

    NASA Astrophysics Data System (ADS)

    Negoita, Gianina Alina

    Ab initio no core methods have become major tools for understanding the properties of light nuclei based on realistic nucleon-nucleon (NN) and three-nucleon (NNN) interactions. A brief description is provided for the inter-nucleon interactions that fit two-body scattering and bound state data, as well as NNN interactions. Major new progress, including the goal of applying these interactions to solve for properties of nuclei, is limited by convergence issues. That is, with the goal of obtaining high precision solutions of the nuclear many-body Hamiltonian with no core methods (all nucleons treated on the same footing), one needs to proceed to very large basis spaces to achieve a convergence pattern suitable for extrapolation to the exact result. This thesis investigates (1) the similarity renormalization group (SRG) approach to soften the interaction, while preserving its phase shift properties, and (2) adoption of a realistic basis space using Woods-Saxon (WS) single-particle wavefunctions. Both have their advantages and limitations, discussed here. For (1), SRG was demonstrated by applying it to a realistic NN interaction, JISP16, in a harmonic oscillator (HO) representation. The degree of interaction softening achieved through a regulator parameter is examined. For (2), new results are obtained with the realistic JISP16 NN interaction in ab initio calculations of light nuclei 4He, 6He and 12C, using a WS basis optimized to minimize the ground-state energy within the truncated no core shell model. These are numerically-intensive many-body calculations. Finally, to gain insight into the potential for no core investigations of heavier nuclei, an initial investigation was obtained for the odd mass A = 47 - 49 region nuclei straddling 48Ca. The motivation for selecting these nuclei stems from the aim of preparing for nuclear double beta-decay studies of 48Ca. In these heavier systems, phenomenological additions to the realistic NN interaction determined by previous

  12. VISION - Verifiable Fuel Cycle Simulation of Nuclear Fuel Cycle Dynamics

    SciTech Connect

    Steven J. Piet; A. M. Yacout; J. J. Jacobson; C. Laws; G. E. Matthern; D. E. Shropshire

    2006-02-01

    The U.S. DOE Advanced Fuel Cycle Initiative’s (AFCI) fundamental objective is to provide technology options that - if implemented - would enable long-term growth of nuclear power while improving sustainability and energy security. The AFCI organization structure consists of four areas; Systems Analysis, Fuels, Separations and Transmutations. The Systems Analysis Working Group is tasked with bridging the program technical areas and providing the models, tools, and analyses required to assess the feasibility of design and deployment options and inform key decision makers. An integral part of the Systems Analysis tool set is the development of a system level model that can be used to examine the implications of the different mixes of reactors, implications of fuel reprocessing, impact of deployment technologies, as well as potential "exit" or "off ramp" approaches to phase out technologies, waste management issues and long-term repository needs. The Verifiable Fuel Cycle Simulation Model (VISION) is a computer-based simulation model that allows performing dynamic simulations of fuel cycles to quantify infrastructure requirements and identify key trade-offs between alternatives. It is based on the current AFCI system analysis tool "DYMOND-US" functionalities in addition to economics, isotopic decay, and other new functionalities. VISION is intended to serve as a broad systems analysis and study tool applicable to work conducted as part of the AFCI and Generation IV reactor development studies.

  13. Microscopic Nuclear Structure Theory: An Overview

    NASA Astrophysics Data System (ADS)

    Barrett, Bruce R.

    1999-10-01

    Around 1990 a Renaissance began in the field of nuclear structure theory, because of the major advances in computer technology and the realization that a fundamental understanding of nuclear properties from basic principles was essential to making future progress not only in nuclear physics but also in other fields, such as astrophysics. Within the time available, a brief survey will be given of the current worldwide efforts to determine microscopically nuclear properties from the new statistical approaches to the ab initio variational calculations and from the recent huge basis-space shell-model investigations with semi-phenomenological interactions to microscopic calculations to determine the effective interaction and other operators for nuclei starting from the free nucleon-nucleon potential.

  14. Progress on nuclear modifications of structure functions

    NASA Astrophysics Data System (ADS)

    Kumano, S.

    2016-03-01

    We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrinooscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function b1 is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact suggests that a new hadronic phenomenon should exist in the tensor-polarized deuteron at high energies, and it will be experimentally investigated at JLab from the end of 2010's.

  15. QCD structure of nuclear interactions

    NASA Astrophysics Data System (ADS)

    Granados, Carlos G.

    The research presented in this dissertation investigated selected processes involving baryons and nuclei in hard scattering reactions. These processes are characterized by the production of particles with large energies and transverse momenta. Through these processes, this work explored both, the constituent (quark) structure of baryons (specifically nucleons and Delta-Isobars), and the mechanisms through which the interactions between these constituents ultimately control the selected reactions. The first of such reactions is the hard nucleon-nucleon elastic scattering, which was studied here considering the quark exchange between the nucleons to be the dominant mechanism of interaction in the constituent picture. In particular, it was found that an angular asymmetry exhibited by proton-neutron elastic scattering data is explained within this framework if a quark-diquark picture dominates the nucleon's structure instead of a more traditional SU(6) three quarks picture. The latter yields an asymmetry around 90o center of mass scattering with a sign opposite to what is experimentally observed. The second process is the hard breakup by a photon of a nucleon-nucleon system in light nuclei. Proton-proton (pp) and proton-neutron (pn) breakup in 3He, and DeltaDelta-isobars production in deuteron breakup were analyzed in the hard rescattering model (HRM), which in conjunction with the quark interchange mechanism provides a Quantum Chromodynamics (QCD) description of the reaction. Through the HRM, cross sections for both channels in 3He photodisintegration were computed without the need of a fitting parameter. The results presented here for pp breakup show excellent agreement with recent experimental data. In DeltaDelta-isobars production in deuteron breakup, HRM angular distributions for the two DeltaDelta channels were compared to the pn channel and to each other. An important prediction fromthis study is that the Delta++Delta- channel consistently dominates Delta+Delta0

  16. Seismic analysis of nuclear power plant structures

    NASA Technical Reports Server (NTRS)

    Go, J. C.

    1973-01-01

    Primary structures for nuclear power plants are designed to resist expected earthquakes of the site. Two intensities are referred to as Operating Basis Earthquake and Design Basis Earthquake. These structures are required to accommodate these seismic loadings without loss of their functional integrity. Thus, no plastic yield is allowed. The application of NASTRAN in analyzing some of these seismic induced structural dynamic problems is described. NASTRAN, with some modifications, can be used to analyze most structures that are subjected to seismic loads. A brief review of the formulation of seismic-induced structural dynamics is also presented. Two typical structural problems were selected to illustrate the application of the various methods of seismic structural analysis by the NASTRAN system.

  17. Nuclear structure and depletion of nuclear isomers using electron linacs

    SciTech Connect

    Carroll, J. J.; Litz, M. S.; Henriquez, S. L.; Burns, D. A.; Netherton, K. A.; Pereira, N. R.; Karamian, S. A.

    2013-04-19

    Long-lived nuclear excited states (isomers) have proven important to understanding nuclear structure. With some isomers having half-lives of decades or longer, and intrinsic energy densities reaching 10{sup 12} J/kg, they have also been suggested for a wide range of applications. The ability to effectively transfer a population of nuclei from an isomer to shorter-lived levels will determine the feasibility of any applications. Here is described a first demonstration of the induced depletion of a population of the 438 year isomer of {sup 108}Ag to its 2.38 min ground state, using 6 MeV bremsstrahlung from a modified medical electron linac. The experiment suggests refinements to be implemented in the future and how a similar approach might be applied to study induced depletion of the 1200 year isomer of {sup 166}Ho.

  18. Computational nuclear structure: Challenges, rewards, and prospects

    SciTech Connect

    Dean, D.J.

    1997-12-01

    The shell model Monte Carlo technique (SMMC) transforms the traditional nuclear shell model problem into a path-integral over auxiliary fields. Applications of the method to studies of various properties of fp-shell nuclei, including Gamow-Teller strengths and distributions, are reviewed. Part of the future of nuclear structure physics lies in the study of nuclei far from beta-stability. The author discusses preliminary work on proton deficient Xe isotopes, and on neutron rich nuclei in the sd-Jp shells.

  19. Elements of Regolith Simulant's Cost Structure

    NASA Technical Reports Server (NTRS)

    Rickman, Douglas L.

    2009-01-01

    The cost of lunar regolith simulants is much higher than many users anticipate. After all, it is nothing more than broken rock. This class will discuss the elements which make up the cost structure for simulants. It will also consider which elements can be avoided under certain circumstances and which elements might be altered by the application of additional research and development.

  20. Analysing Deep Structure in Games and Simulations.

    ERIC Educational Resources Information Center

    Gredler, Margaret Bell

    1990-01-01

    Discussion of the design of games and simulations focuses on the fundamental defining features called deep structure. The two main levels of interaction in games and simulations are described; generalized reinforcers are discussed; types of defective contingencies are explained, including escape or avoidance behaviors; and the concept of negative…

  1. Structural Reliability and Monte Carlo Simulation.

    ERIC Educational Resources Information Center

    Laumakis, P. J.; Harlow, G.

    2002-01-01

    Analyzes a simple boom structure and assesses its reliability using elementary engineering mechanics. Demonstrates the power and utility of Monte-Carlo simulation by showing that such a simulation can be implemented more readily with results that compare favorably to the theoretical calculations. (Author/MM)

  2. Simulations of nuclear resonance fluorescence in GEANT4

    NASA Astrophysics Data System (ADS)

    Lakshmanan, Manu N.; Harrawood, Brian P.; Rusev, Gencho; Agasthya, Greeshma A.; Kapadia, Anuj J.

    2014-11-01

    The nuclear resonance fluorescence (NRF) technique has been used effectively to identify isotopes based on their nuclear energy levels. Specific examples of its modern-day applications include detecting spent nuclear waste and cargo scanning for homeland security. The experimental designs for these NRF applications can be more efficiently optimized using Monte Carlo simulations before the experiment is implemented. One of the most widely used Monte Carlo physics simulations is the open-source toolkit GEANT4. However, NRF physics has not been incorporated into the GEANT4 simulation toolkit in publicly available software. Here we describe the development and testing of an NRF simulation in GEANT4. We describe in depth the development and architecture of this software for the simulation of NRF in any isotope in GEANT4; as well as verification and validation testing of the simulation for NRF in boron. In the verification testing, the simulation showed agreement with the analytical model to be within 0.6% difference for boron and iron. In the validation testing, the simulation showed agreement to be within 20.5% difference with the experimental measurements for boron, with the percent difference likely due to small uncertainties in beam polarization, energy distribution, and detector composition.

  3. Simulations of Metallic Nanoscale Structures

    NASA Astrophysics Data System (ADS)

    Jacobsen, Karsten W.

    2003-03-01

    Density-functional-theory calculations can be used to understand and predict materials properties based on their nanoscale composition and structure. In combination with efficient search algorithms DFT can furthermore be applied in the nanoscale design of optimized materials. The first part of the talk will focus on two different types of nanostructures with an interesting interplay between chemical activity and conducting states. MoS2 nanoclusters are known for their catalyzing effect in the hydrodesulfurization process which removes sulfur-containing molecules from oil products. MoS2 is a layered material which is insulating. However, DFT calculations indicates the exsistence of metallic states at some of the edges of MoS2 nanoclusters, and the calculations show that the conducting states are not passivated by for example the presence of hydrogen gas. The edge states may play an important role for the chemical activity of MoS_2. Metallic nanocontacts can be formed during the breaking of a piece of metal, and atomically thin structures with conductance of only a single quantum unit may be formed. Such open metallic structures are chemically very active and susceptible to restructuring through interactions with molecular gases. DFT calculations show for example that atomically thin gold wires may incorporate oxygen atoms forming a new type of metallic nanowire. Adsorbates like hydrogen may also affect the conductance. In the last part of the talk I shall discuss the possibilities for designing alloys with optimal mechanical properties based on a combination of DFT calculations with genetic search algorithms. Simulaneous optimization of several parameters (stability, price, compressibility) is addressed through the determination of Pareto optimal alloy compositions within a large database of more than 64000 alloys.

  4. Clustering Aspects in Nuclear Structure and Collisions

    NASA Astrophysics Data System (ADS)

    Horiuchi, H.

    Four topics on nuclear clustering are discussed. The first subject is about the cluster formation in dilute matter which we think is now observed in heavy ion collisions at hundreds MeV/nucleon. The second subject is about our new proposal of the existense of alpha condensed states in light nuclei. Two other subjects are both about the clustering in neutron-rich nuclei. One is the cluster structures in neutron-rich Be and B isotopes. In these isotopes, the clustering prevails as fundamental characters of nuclear structure. The other is the report of our recent study about the possible relation of the clustering with the breaking of the neutron magic number N=20 in 32Mg and 30Ne.

  5. Initial Operation of the Nuclear Thermal Rocket Element Environmental Simulator

    NASA Technical Reports Server (NTRS)

    Emrich, William J., Jr.; Pearson, J. Boise; Schoenfeld, Michael P.

    2015-01-01

    The Nuclear Thermal Rocket Element Environmental Simulator (NTREES) facility is designed to perform realistic non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and fuel materials. Although the NTREES facility cannot mimic the neutron and gamma environment of an operating NTR, it can simulate the thermal hydraulic environment within an NTR fuel element to provide critical information on material performance and compatibility. The NTREES facility has recently been upgraded such that the power capabilities of the facility have been increased significantly. At its present 1.2 MW power level, more prototypical fuel element temperatures nay now be reached. The new 1.2 MW induction heater consists of three physical units consisting of a transformer, rectifier, and inverter. This multiunit arrangement facilitated increasing the flexibility of the induction heater by more easily allowing variable frequency operation. Frequency ranges between 20 and 60 kHz can accommodated in the new induction heater allowing more representative power distributions to be generated within the test elements. The water cooling system was also upgraded to so as to be capable of removing 100% of the heat generated during testing In this new higher power configuration, NTREES will be capable of testing fuel elements and fuel materials at near-prototypic power densities. As checkout testing progressed and as higher power levels were achieved, several design deficiencies were discovered and fixed. Most of these design deficiencies were related to stray RF energy causing various components to encounter unexpected heating. Copper shielding around these components largely eliminated these problems. Other problems encountered involved unexpected movement in the coil due to electromagnetic forces and electrical arcing between the coil and a dummy test article. The coil movement and arcing which were encountered during the checkout testing effectively destroyed the induction coil in use at

  6. Nuclear structure models: Applications and development

    SciTech Connect

    Semmes, P.B.

    1992-07-01

    This report discusses the following topics: Studies of superdeformed States; Signature Inversion in Odd-Odd Nuclei: A fingerprint of Triaxiality; Signature Inversion in {sup 120}Cs - Evidence for a Residual p-n Interaction; Signatures of {gamma} Deformation in Nuclei and an Application to {sup 125}Xe; Nuclear Spins and Moments: Fundamental Structural Information; and Electromagnetic Properties of {sup 181}Ir: Evidence of {beta} Stretching.

  7. Nuclear structure and sub-barrier fusion

    SciTech Connect

    Esbensen, H. . Cyclotron Lab. Argonne National Lab., IL )

    1990-01-01

    The influence of nuclear structure on heavy-ion fusion and elastic scattering, at energies near and below the Coulomb barrier, is discussed within the coupled channels formalism. The coupled channels approach provides a consistent description of the enhancement of sub-barrier fusion and the energy dependence of the effective potential for elastic scattering. This is illustrated by comparison to the data for several systems. 48 refs., 4 figs.

  8. Photonic band gap structure simulator

    DOEpatents

    Chen, Chiping; Shapiro, Michael A.; Smirnova, Evgenya I.; Temkin, Richard J.; Sirigiri, Jagadishwar R.

    2006-10-03

    A system and method for designing photonic band gap structures. The system and method provide a user with the capability to produce a model of a two-dimensional array of conductors corresponding to a unit cell. The model involves a linear equation. Boundary conditions representative of conditions at the boundary of the unit cell are applied to a solution of the Helmholtz equation defined for the unit cell. The linear equation can be approximated by a Hermitian matrix. An eigenvalue of the Helmholtz equation is calculated. One computation approach involves calculating finite differences. The model can include a symmetry element, such as a center of inversion, a rotation axis, and a mirror plane. A graphical user interface is provided for the user's convenience. A display is provided to display to a user the calculated eigenvalue, corresponding to a photonic energy level in the Brilloin zone of the unit cell.

  9. Meeting report: mitosis and nuclear structure.

    PubMed

    Meadows, John C; Graumann, Katja; Platani, Melpi; Schweizer, Nina; Shimi, Takeshi; Vagnarelli, Paola; Gatlin, Jesse C

    2013-11-15

    The Company of Biologists Workshop entitled 'Mitosis and Nuclear Structure' was held at Wiston House, West Sussex in June 2013. It provided a unique and timely opportunity for leading experts from different fields to discuss not only their own work but also its broader context. Here we present the proceedings of this meeting and several major themes that emerged from the crosstalk between the two, as it turns out, not so disparate fields of mitosis and nuclear structure. Co-chaired by Katherine Wilson (Johns Hopkins School of Medicine, Baltimore, MD), Timothy Mitchison (Harvard University, Cambridge, MA) and Michael Rout (Rockefeller University, New York, NY), this workshop brought together a small group of scientists from a range of disciplines to discuss recent advances and connections between the areas of mitosis and nuclear structure research. Several early-career researchers (students, postdoctoral researchers, junior faculty) participated along with 20 senior scientists, including the venerable and affable Nobel Laureate Tim Hunt. Participants were encouraged to embrace unconventional thinking in the 'scientific sandbox' created by this unusual combination of researchers in the inspiring, isolated setting of the 16th-century Wiston House. PMID:24244037

  10. Nuclear structure functions at small x

    SciTech Connect

    Jalilian-Marian, Jamal

    2009-11-15

    I study the nuclear structure function F{sub 2}{sup A} and its logarithmic derivative in the high-energy limit (small-x region) using the color glass condensate formalism. In this limit the structure function F{sub 2} depends on the quark-antiquark dipole-target scattering cross section N{sub F}(x{sub bj},r{sub t},b{sub t}). The same dipole cross section appears in single-hadron and hadron-photon production cross sections in the forward rapidity region in deuteron (proton)-nucleus collisions at high energy, that is, at energies available at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). I use a parametrization of the dipole cross section, which has successfully been used to describe the deuteron-gold data at the RHIC, to compute the nuclear structure function F{sub 2}{sup A} and its log Q{sup 2} derivative (which is related to gluon distribution function in the double log limit). I provide a quantitative estimate of the nuclear shadowing of F{sub 2}{sup A} and the gluon distribution function in the kinematic region relevant to a future electron-ion collider.

  11. Electromagnetic studies of nucleon and nuclear structure

    SciTech Connect

    Heisenberg, J.H.; Calarco, J.R.; Hersman, F.W.; Dawson, J.F.

    1993-06-01

    Important objectives of the group are the study of subatomic structure through experimental measurements and the interpretation of the data through modeling. The common theme that unifies the studies of strong interactions and hadronic systems is the effort to determine the electromagnetic response as completely as possible. The general approach is coincidence detection of exclusive final states and determination of the dependence on the spin variables using polarized beams and targets and outgoing nucleon polarimetry. Direct reaction and giant resonance studies of electron quasi-elastic scattering on {sup 12}C and {sup 16}O are reported, as well as work on nuclear structure models and instrumentation development.

  12. Structural Materials for Innovative Nuclear Systems

    SciTech Connect

    Yvon, Pascal

    2011-07-01

    This series of slides deal with: the goals for advanced fission reactor systems; the requirements for structural materials; a focus on two important types of materials: ODS and CMC; a focus on materials under irradiation (multiscale modelling, experimental simulation, 'smart' experiments in materials testing reactors); some concluding remarks.

  13. Structural model uncertainty in stochastic simulation

    SciTech Connect

    McKay, M.D.; Morrison, J.D.

    1997-09-01

    Prediction uncertainty in stochastic simulation models can be described by a hierarchy of components: stochastic variability at the lowest level, input and parameter uncertainty at a higher level, and structural model uncertainty at the top. It is argued that a usual paradigm for analysis of input uncertainty is not suitable for application to structural model uncertainty. An approach more likely to produce an acceptable methodology for analyzing structural model uncertainty is one that uses characteristics specific to the particular family of models.

  14. Probabilistic simulation of uncertainties in thermal structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Shiao, Michael

    1990-01-01

    Development of probabilistic structural analysis methods for hot structures is a major activity at NASA-Lewis, and consists of five program elements: (1) probabilistic loads, (2) probabilistic finite element analysis, (3) probabilistic material behavior, (4) assessment of reliability and risk, and (5) probabilistic structural performance evaluation. Attention is given to quantification of the effects of uncertainties for several variables on High Pressure Fuel Turbopump blade temperature, pressure, and torque of the Space Shuttle Main Engine; the evaluation of the cumulative distribution function for various structural response variables based on assumed uncertainties in primitive structural variables; evaluation of the failure probability; reliability and risk-cost assessment; and an outline of an emerging approach for eventual hot structures certification. Collectively, the results demonstrate that the structural durability/reliability of hot structural components can be effectively evaluated in a formal probabilistic framework. In addition, the approach can be readily extended to computationally simulate certification of hot structures for aerospace environments.

  15. Requirements for advanced simulation of nuclear reactor and chemicalseparation plants.

    SciTech Connect

    Palmiotti, G.; Cahalan, J.; Pfeiffer, P.; Sofu, T.; Taiwo, T.; Wei,T.; Yacout, A.; Yang, W.; Siegel, A.; Insepov, Z.; Anitescu, M.; Hovland,P.; Pereira, C.; Regalbuto, M.; Copple, J.; Willamson, M.

    2006-12-11

    This report presents requirements for advanced simulation of nuclear reactor and chemical processing plants that are of interest to the Global Nuclear Energy Partnership (GNEP) initiative. Justification for advanced simulation and some examples of grand challenges that will benefit from it are provided. An integrated software tool that has its main components, whenever possible based on first principles, is proposed as possible future approach for dealing with the complex problems linked to the simulation of nuclear reactor and chemical processing plants. The main benefits that are associated with a better integrated simulation have been identified as: a reduction of design margins, a decrease of the number of experiments in support of the design process, a shortening of the developmental design cycle, and a better understanding of the physical phenomena and the related underlying fundamental processes. For each component of the proposed integrated software tool, background information, functional requirements, current tools and approach, and proposed future approaches have been provided. Whenever possible, current uncertainties have been quoted and existing limitations have been presented. Desired target accuracies with associated benefits to the different aspects of the nuclear reactor and chemical processing plants were also given. In many cases the possible gains associated with a better simulation have been identified, quantified, and translated into economical benefits.

  16. Survey of Dynamic Simulation Programs for Nuclear Fuel Reprocessing

    SciTech Connect

    Troy J. Tranter; Daryl R. Haefner

    2008-06-01

    The absence of any industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other industries. Modeling programs to simulate the dynamic behavior of nuclear fuel separations and processing were originally developed to support the US government’s mission of weapons production and defense fuel recovery. Consequently there has been little effort is the US devoted towards improving this specific process simulation capability during the last two or three decades. More recent work has been focused on elucidating chemical thermodynamics and developing better models of predicting equilibrium in actinide solvent extraction systems. These equilibrium models have been used to augment flowsheet development and testing primarily at laboratory scales. The development of more robust and complete process models has not kept pace with the vast improvements in computational power and user interface and is significantly behind simulation capability in other chemical processing and separation fields.

  17. Simulating Vibrations in a Complex Loaded Structure

    NASA Technical Reports Server (NTRS)

    Cao, Tim T.

    2005-01-01

    The Dynamic Response Computation (DIRECT) computer program simulates vibrations induced in a complex structure by applied dynamic loads. Developed to enable rapid analysis of launch- and landing- induced vibrations and stresses in a space shuttle, DIRECT also can be used to analyze dynamic responses of other structures - for example, the response of a building to an earthquake, or the response of an oil-drilling platform and attached tanks to large ocean waves. For a space-shuttle simulation, the required input to DIRECT includes mathematical models of the space shuttle and its payloads, and a set of forcing functions that simulates launch and landing loads. DIRECT can accommodate multiple levels of payload attachment and substructure as well as nonlinear dynamic responses of structural interfaces. DIRECT combines the shuttle and payload models into a single structural model, to which the forcing functions are then applied. The resulting equations of motion are reduced to an optimum set and decoupled into a unique format for simulating dynamics. During the simulation, maximum vibrations, loads, and stresses are monitored and recorded for subsequent analysis to identify structural deficiencies in the shuttle and/or payloads.

  18. Nuclear Structure and Decay Data Evaluation: Challenges and Perspectives

    NASA Astrophysics Data System (ADS)

    Kondev, F. G.; Tuli, J. K.

    2003-10-01

    The expression ``Nuclear Structure and Decay Data'' refers to complex nuclear level schemes and tables of numerical values, which quantify fundamental properties of nuclear structure, such as level energies, quantum numbers and state lifetimes, as well as various decay modes and associated radiation. These data are not only at the core of basic nuclear structure and nuclear astrophysics research, but they are also relevant for many applied technologies, including nuclear energy production, reactor design and safety, medical diagnostic and radiotherapy, health physics, environmental research and monitoring, safeguards, material analysis, etc. The mission of the Nuclear Structure and Decay Data Working Group of the US DOE funded Nuclear Data Program is to evaluate, compile, maintain, and disseminate nuclear structure and decay data for all known nuclei (more than 2900!). The network's principal effort is devoted to the timely revision of information in the ENSDF (Evaluated Nuclear Structure Data File) database. However, in recent years, special attention has been given to topical evaluations of properties of particular interest to the nuclear structure community, such as log ft values, α- and proton decay properties, super-deformed and magnetic dipole collective structures, nuclear moments, and nuclear isomers (under development). This presentation will briefly review recent achievements of the network, present on-going activities, and reflect on ideas for future projects and challenges in the field of nuclear structure and decay data evaluation.

  19. Parallelization and automatic data distribution for nuclear reactor simulations

    SciTech Connect

    Liebrock, L.M.

    1997-07-01

    Detailed attempts at realistic nuclear reactor simulations currently take many times real time to execute on high performance workstations. Even the fastest sequential machine can not run these simulations fast enough to ensure that the best corrective measure is used during a nuclear accident to prevent a minor malfunction from becoming a major catastrophe. Since sequential computers have nearly reached the speed of light barrier, these simulations will have to be run in parallel to make significant improvements in speed. In physical reactor plants, parallelism abounds. Fluids flow, controls change, and reactions occur in parallel with only adjacent components directly affecting each other. These do not occur in the sequentialized manner, with global instantaneous effects, that is often used in simulators. Development of parallel algorithms that more closely approximate the real-world operation of a reactor may, in addition to speeding up the simulations, actually improve the accuracy and reliability of the predictions generated. Three types of parallel architecture (shared memory machines, distributed memory multicomputers, and distributed networks) are briefly reviewed as targets for parallelization of nuclear reactor simulation. Various parallelization models (loop-based model, shared memory model, functional model, data parallel model, and a combined functional and data parallel model) are discussed along with their advantages and disadvantages for nuclear reactor simulation. A variety of tools are introduced for each of the models. Emphasis is placed on the data parallel model as the primary focus for two-phase flow simulation. Tools to support data parallel programming for multiple component applications and special parallelization considerations are also discussed.

  20. DEVELOPMENT OF NUCLEAR POWER PLANT SIMULATORS FOR SOVIET-DESIGNED NUCLEAR REACTORS.

    SciTech Connect

    Kohut, P.; Tutu, N.K.; Cleary, E.J.; Erickson, K.G.; Yoder, J.; Kroshilin, A.

    2001-01-07

    The US Department of Energy (US DOE), under the US government's International Nuclear Safety Program (INSP), is implementing a program of developing and providing simulators for many of the Russian and Ukrainian Nuclear Power Plants (NPPs). Pacific Northwest National Laboratory (PNNL) and Brookhaven National Laboratory (BNL) manage and provide technical oversight of the various INSP simulator projects for DOE. The program also includes a simulator technology transfer process to simulator design organizations in Russia and Ukraine. Training programs, installation of new simulators, and enhancements in existing simulators, are viewed as providing a relatively fast and cost-effective technology transfer that will result in measurable improvement in the safety culture and operation of NPPs. A review of this program, its present status, and its accomplishments are provided in this paper.

  1. Opportunities in nuclear structure and reactions

    NASA Astrophysics Data System (ADS)

    Nunes, Filomena

    2015-10-01

    The last decade has seen important advances in the area of low energy nuclear physics. New measurements have provided crucial insight into the behavior of nuclei at the limits of stability, including the mapping of the neutron dripline up to Oxygen, investigations of unbound nuclear states, and the discovery of new super-heavy elements. In parallel we have seen a revolution in low-energy nuclear theory, moving toward quantified predictability, rooted in the underlying inter-nucleon forces. But the next decade offers even more opportunities with a new generation factory of rare isotopes, and the anticipated developments in high performance computing. The Facility for Rare Isotope Beams coupled with new state-of-the-art detectors will allow us to access a large fraction of the necessary information for the r-process responsible for making at least half of the heavy elements in our universe. FRIB will provide the needed intensities to study global nuclear properties, shell structure, and collective phenomena far from stability. Key measurements are anticipated, at various facilities, which will inform symmetry tests with rare isotopes. We expect to put strict constraints on the equation of state. These and many other opportunities will be highlighted in this overview talk.

  2. Numerically simulating the sandwich plate system structures

    NASA Astrophysics Data System (ADS)

    Feng, Guo-Qing; Li, Gang; Liu, Zhi-Hui; Niu, Huai-Lei; Li, Chen-Feng

    2010-09-01

    Sandwich plate systems (SPS) are advanced materials that have begun to receive extensive attention in naval architecture and ocean engineering. At present, according to the rules of classification societies, a mixture of shell and solid elements are required to simulate an SPS. Based on the principle of stiffness decomposition, a new numerical simulation method for shell elements was proposed. In accordance with the principle of stiffness decomposition, the total stiffness can be decomposed into the bending stiffness and shear stiffness. Displacement and stress response related to bending stiffness was calculated with the laminated shell element. Displacement and stress response due to shear was calculated by use of a computational code write by FORTRAN language. Then the total displacement and stress response for the SPS was obtained by adding together these two parts of total displacement and stress. Finally, a rectangular SPS plate and a double-bottom structure were used for a simulation. The results show that the deflection simulated by the elements proposed in the paper is larger than the same simulated by solid elements and the analytical solution according to Hoff theory and approximate to the same simulated by the mixture of shell-solid elements, and the stress simulated by the elements proposed in the paper is approximate to the other simulating methods. So compared with calculations based on a mixture of shell and solid elements, the numerical simulation method given in the paper is more efficient and easier to do.

  3. Forging the link between nuclear reactions and nuclear structure

    NASA Astrophysics Data System (ADS)

    Dickhoff, W. H.

    2016-06-01

    A review of the recent applications of the dispersive optical model (DOM) is presented. Emphasis is on the nonlocal implementation of the DOM that is capable of describing ground-state properties accurately when data like the nuclear charge density are available. The present understanding of the role of short- and long-range physics in determining proton properties near the Fermi energy for stable closed-shell nuclei has relied mostly on data from the (e, e' p) reaction. Hadronic tools to extract such spectroscopic information have been hampered by the lack of a consistent reaction description that provides unambiguous and undisputed results. The DOM, conceived by Claude Mahaux, provides a unified description of both elastic nucleon scattering and structure information related to single-particle properties below the Fermi energy. We have recently introduced a nonlocal dispersive optical potential for both the real and imaginary part. Nonlocal absorptive potentials yield equivalent elastic differential cross sections for 40Ca as compared to local ones but change the l-dependent absorption profile suggesting important consequences for the analysis of nuclear reactions. Below the Fermi energy, nonlocality is essential for an accurate representation of particle number and the nuclear charge density. Spectral properties implied by (e, e' p) and (p, 2p) reactions are correctly described, including the energy distribution of about 10% high-momentum protons obtained at Jefferson Lab. The nonlocal DOM allows a complete description of experimental data both above (up to 200 MeV) and below the Fermi energy in 40Ca. It is further demonstrated that elastic nucleon-nucleus scattering data constrain the spectral strength in the continuum of orbits that are nominally bound in the independent-particle model. Extension of this analysis to 48Ca allows a prediction of the neutron skin of this nucleus that is larger than most predictions made so far.

  4. Inspection of Nuclear Power Plant Containment Structures

    SciTech Connect

    Graves, H.L.; Naus, D.J.; Norris, W.E.

    1998-12-01

    Safety-related nuclear power plant (NPP) structures are designed to withstand loadings from a number of low-probability external and interval events, such as earthquakes, tornadoes, and loss-of-coolant accidents. Loadings incurred during normal plant operation therefore generally are not significant enough to cause appreciable degradation. However, these structures are susceptible to aging by various processes depending on the operating environment and service conditions. The effects of these processes may accumulate within these structures over time to cause failure under design conditions, or lead to costly repair. In the late 1980s and early 1990s several occurrences of degradation of NPP structures were discovered at various facilities (e.g., corrosion of pressure boundary components, freeze- thaw damage of concrete, and larger than anticipated loss of prestressing force). Despite these degradation occurrences and a trend for an increasing rate of occurrence, in-service inspection of the safety-related structures continued to be performed in a somewhat cursory manner. Starting in 1991, the U.S. Nuclear Regulatory Commission (USNRC) published the first of several new requirements to help ensure that adequate in-service inspection of these structures is performed. Current regulatory in-service inspection requirements are reviewed and a summary of degradation experience presented. Nondestructive examination techniques commonly used to inspect the NPP steel and concrete structures to identify and quantify the amount of damage present are reviewed. Finally, areas where nondestructive evaluation techniques require development (i.e., inaccessible portions of the containment pressure boundary, and thick heavily reinforced concrete sections are discussed.

  5. Structural Biology of Nuclear Auxin Action.

    PubMed

    Dinesh, Dhurvas Chandrasekaran; Villalobos, Luz Irina A Calderón; Abel, Steffen

    2016-04-01

    Auxin coordinates plant development largely via hierarchical control of gene expression. During the past decades, the study of early auxin genes paired with the power of Arabidopsis genetics have unraveled key nuclear components and molecular interactions that perceive the hormone and activate primary response genes. Recent research in the realm of structural biology allowed unprecedented insight into: (i) the recognition of auxin-responsive DNA elements by auxin transcription factors; (ii) the inactivation of those auxin response factors by early auxin-inducible repressors; and (iii) the activation of target genes by auxin-triggered repressor degradation. The biophysical studies reviewed here provide an impetus for elucidating the molecular determinants of the intricate interactions between core components of the nuclear auxin response module. PMID:26651917

  6. Nuclear structure of {sup 102}Mo

    SciTech Connect

    Rahman, M.A.; Chowdhury, M.S.

    2006-05-15

    Nuclear structure of the {sup 102}Mo nucleus has been studied using the {sup 100}Mo(t,p){sup 102}Mo reaction with the triton beam energy of 12 MeV obtained from the tandem Van de Graaff accelerator and a multichannel magnetic spectrograph. Proton spectra are obtained at 12 different angles from 5 deg. to 87.5 deg., at an interval of 7.5 deg. and are detected in nuclear emulsion plates. Thirty-five levels in the energy range from 0.000 to 3.248 MeV have been observed. The results yield a number of new levels with spin assignments. Absolute differential cross sections for the levels have been measured. The experimental angular distributions are compared with the theoretical distorted-wave Born approximation calculations to determine L and J{sup {pi}} values. The present results are compared with the previous results.

  7. Gogny HFB prediction of nuclear structure properties

    SciTech Connect

    Goriely, S.; Hilaire, S.; Girod, M.

    2011-10-28

    Large scale mean field calculations from proton to neutron drip lines have been performed using the Hartree-Fock-Bogoliubov method based on the Gogny nucleon-nucleon effective interaction. This extensive study has shown the ability of the method to reproduce bulk nuclear structure data available experimentally. This includes nuclear masses, radii, matter densities, deformations, moment of inertia as well as collective mode (low energy and giant resonances). In particular, the first mass table based on a Gogny-Hartree-Fock-Bogolyubov calculation including an explicit and coherent account of all the quadrupole correlation energies is presented. The rms deviation with respect to essentially all the available mass data is 798 keV. Nearly 8000 nuclei have been studied under the axial symmetry hypothesis and going beyond the mean-field approach.

  8. Nuclear structure studies far from the line of beta stability

    SciTech Connect

    Avignone, F.T. III

    1986-04-15

    This report includes research activities concerning nuclear structure research of neutron rich and neutron deficient isotopes. Individual sections deal with Coulomb interactions; lifetime measurements of nuclei; calculations and Monte Carlo simulations for predicting responses of Ge and NaI(Tl) detectors to gamma radiation; and beta decay, energy levels, and mass measurements of selected isotopes. The research program features the discovery of new isotopes via their delayed proton decay and the detailed investigation of the beta-delayed, proton spectra. This report covers activities through the contract period from 1979 through 1985. 10 refs. (DWL)

  9. Reactor Subsystem Simulation for Nuclear Hybrid Energy Systems

    SciTech Connect

    Shannon Bragg-Sitton; J. Michael Doster; Alan Rominger

    2012-09-01

    Preliminary system models have been developed by Idaho National Laboratory researchers and are currently being enhanced to assess integrated system performance given multiple sources (e.g., nuclear + wind) and multiple applications (i.e., electricity + process heat). Initial efforts to integrate a Fortran-based simulation of a small modular reactor (SMR) with the balance of plant model have been completed in FY12. This initial effort takes advantage of an existing SMR model developed at North Carolina State University to provide initial integrated system simulation for a relatively low cost. The SMR subsystem simulation details are discussed in this report.

  10. Nuclear structure/nuclei far from stability

    SciTech Connect

    Casten, R.F.; Garrett, J.D.; Moller, P.; Bauer, W.W.; Brenner, D.S.; Butler, G.W.; Crawford, J.E.; Davids, C.N.; Dyer, P.L.; Gregorich, K.; Hagbert, E.G.; Hamilton, W.D.; Harar, S.; Haustein, P.E.; Hayes, A.C.; Hoffman, D.C.; Hsu, H.H.; Madland, D.G.; Myers, W.D.; Penttila, H.T.; Ragnarsson, I.; Reeder, P.L.; Robertson, G.H.; Rowley, N.; Schreiber, F.; Seifert, H.L.; Sherrill, B.M.; Siciliano, E.R.; Sprouse, G.D.; Stephens, F

    1990-01-01

    This report outlines some of the nuclear structure topics discussed at the Los Alamos Workshop on the Science of Intense Radioactive Ion Beams (RIB). In it we also tried to convey some of the excitement of the participants for utilizing RIBs in their future research. The introduction of radioactive beams promises to be a major milestone for nuclear structure perhaps even more important than the last such advance in beams based on the advent of heavy-ion accelerators in the 1960's. RIBs not only will allow a vast number of new nuclei to be studies at the extremes of isospin, but the variety of combinations of exotic proton and neutron configurations should lead to entirely new phenomena. A number of these intriguing new studies and the profound consequences that they promise for understanding the structure of the atomic nucleus, nature's only many-body, strongly-inteacting quantum system, are discussed in the preceeding sections. However, as with any scientific frontier, the most interesting phenomena probably will be those that are not anticipated--they will be truly new.

  11. Computer simulation of two-phase flow in nuclear reactors

    SciTech Connect

    Wulff, W.

    1992-09-01

    Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited for two-phase flow analysis in nuclear reactors than the two-fluid model, because of the latter`s closure problem. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost.

  12. Superheavy Element Synthesis And Nuclear Structure

    SciTech Connect

    Ackermann, D.; Block, M.; Burkhard, H.-G.; Heinz, S.; Hessberger, F. P.; Khuyagbaatar, J.; Kojouharov, I.; Mann, R.; Maurer, J.; Antalic, S.; Saro, S.; Venhart, M.; Hofmann, S.; Leino, M.; Uusitalo, J.; Nishio, K.; Popeko, A. G.; Yeremin, A. V.

    2009-08-26

    After the successful progress in experiments to synthesize superheavy elements (SHE) throughout the last decades, advanced nuclear structure studies in that region have become feasible in recent years thanks to improved accelerator, separation and detection technology. The means are evaporation residue(ER)-alpha-alpha and ER-alpha-gamma coincidence techniques complemented by conversion electron (CE) studies, applied after a separator. Recent examples of interesting physics to be discovered in this region of the chart of nuclides are the studies of K-isomers observed in {sup 252,254}No and in {sup 270}Ds.

  13. Chiral nucleon-nucleon forces in nuclear structure calculations

    NASA Astrophysics Data System (ADS)

    Coraggio, L.; Gargano, A.; Holt, J. W.; Itaco, N.; Machleidt, R.; Marcucci, L. E.; Sammarruca, F.

    2016-05-01

    Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.

  14. Proline puckering parameters for collagen structure simulations

    SciTech Connect

    Wu, Di

    2015-03-15

    Collagen is made of triple helices rich in proline residues, and hence is influenced by the conformational motions of prolines. Because the backbone motions of prolines are restricted by the helical structures, the only side chain motion—proline puckering—becomes an influential factor that may affect the stability of collagen structures. In molecular simulations, a proper proline puckering population is desired so to yield valid results of the collagen properties. Here we design the proline puckering parameters in order to yield suitable proline puckering populations as demonstrated in the experimental results. We test these parameters in collagen and the proline dipeptide simulations. Compared with the results of the PDB and the quantum calculations, we propose the proline puckering parameters for the selected collagen model simulations.

  15. Simulating the formation of cosmic structure.

    PubMed

    Frenk, C S

    2002-06-15

    A timely combination of new theoretical ideas and observational discoveries has brought about significant advances in our understanding of cosmic evolution. Computer simulations have played a key role in these developments by providing the means to interpret astronomical data in the context of physical and cosmological theory. In the current paradigm, our Universe has a flat geometry, is undergoing accelerated expansion and is gravitationally dominated by elementary particles that make up cold dark matter. Within this framework, it is possible to simulate in a computer the emergence of galaxies and other structures from small quantum fluctuations imprinted during an epoch of inflationary expansion shortly after the Big Bang. The simulations must take into account the evolution of the dark matter as well as the gaseous processes involved in the formation of stars and other visible components. Although many unresolved questions remain, a coherent picture for the formation of cosmic structure is now beginning to emerge. PMID:12804279

  16. Hierarchical Simulation of Hot Composite Structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Murthy, P. L. N.; Singhal, S. N.

    1993-01-01

    Computational procedures are described to simulate the thermal and mechanical behavior of high temperature metal matrix composites (HT-MMC) in the following three broad areas: (1) Behavior of HT-MMC's from micromechanics to laminate via Metal Matrix Composite Analyzer (METCAN), (2) tailoring of HT-MMC behavior for optimum specific performance via Metal Matrix Laminate Tailoring (MMLT), and (3) HT-MMC structural response for hot structural components via High Temperature Composite Analyzer (HITCAN). Representative results from each area are presented to illustrate the effectiveness of computational simulation procedures. The sample case results show that METCAN can be used to simulate material behavior such as strength, stress-strain response, and cyclic life in HTMMC's; MMLT can be used to tailor the fabrication process for optimum performance such as that for in-service load carrying capacity of HT-MMC's; and HITCAN can be used to evaluate static fracture and fatigue life of hot pressurized metal matrix composite rings.

  17. Computational Simulation of Composite Structural Fatigue

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon

    2004-01-01

    Progressive damage and fracture of composite structures subjected to monotonically increasing static, tension-tension cyclic, pressurization, and flexural cyclic loading are evaluated via computational simulation. Constituent material properties, stress and strain limits are scaled up to the structure level to evaluate the overall damage and fracture propagation for composites. Damage initiation, growth, accumulation, and propagation to fracture due to monotonically increasing static and cyclic loads are included in the simulations. Results show the number of cycles to failure at different temperatures and the damage progression sequence during different degradation stages. A procedure is outlined for use of computational simulation data in the assessment of damage tolerance, determination of sensitive parameters affecting fracture, and interpretation of results with insight for design decisions.

  18. Computational Simulation of Composite Structural Fatigue

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Chamis, Christos C. (Technical Monitor)

    2005-01-01

    Progressive damage and fracture of composite structures subjected to monotonically increasing static, tension-tension cyclic, pressurization, and flexural cyclic loading are evaluated via computational simulation. Constituent material properties, stress and strain limits are scaled up to the structure level to evaluate the overall damage and fracture propagation for composites. Damage initiation, growth, accumulation, and propagation to fracture due to monotonically increasing static and cyclic loads are included in the simulations. Results show the number of cycles to failure at different temperatures and the damage progression sequence during different degradation stages. A procedure is outlined for use of computational simulation data in the assessment of damage tolerance, determination of sensitive parameters affecting fracture, and interpretation of results with insight for design decisions.

  19. Structured Debriefing in Simulation-Based Education.

    PubMed

    Palaganas, Janice C; Fey, Mary; Simon, Robert

    2016-02-01

    Debriefing following a simulation event is a conversational period for reflection and feedback aimed at sustaining or improving future performance. It is considered by many simulation educators to be a critical activity for learning in simulation-based education. Deep learning can be achieved during debriefing and often depends on the facilitation skills of the debriefer as well as the learner's perceptions of a safe and supportive learning environment as created by the debriefer. On the other hand, poorly facilitated debriefings may create adverse learning, generate bad feelings, and may lead to a degradation of clinical performance, self-reflection, or harm to the educator-learner relationship. The use of a structure that recognizes logical and sequential phases during debriefing can assist simulation educators to achieve a deep level of learning. PMID:26909457

  20. Microscopic Approaches to Nuclear Structure: Configuration Interaction

    SciTech Connect

    Ormand, W E

    2007-09-21

    The configuration interaction (CI) approach to solving the nuclear many-body problem, also known as the interacting shell model, has proven to be powerful tool in understanding the structure of nuclei. The principal criticism of past applications of the shell model is the reliance on empirical tuning to interaction matrix elements. If an accurate description of nuclei far from the valley of stability, where little or no data is available, a more fundamental approach is needed. This starts with recent ab initio approaches with effective interactions in the no-core shell model (NCSM). Using effective-field theory for guidance, fully ab initio descriptions of nuclei up to {sup 16}O with QCD based NN, NNN, and NNNN interactions will be possible within the next five years. An important task is then to determine how to use these NCSM results to develop effective interactions to describe heavier nuclei without the need to resort to an empirical retuning with every model space. Thus, it is likely that more traditional CI applications utilizing direct diagonalization and more fundamental interactions will be applicable to nuclei with perhaps up to one hundred constituents. But, these direct diagonalization CI applications will always be computationally limited due to the rapid increase in the number of configurations with particle number. Very recently, the shifted-contour method has been applied to the Auxiliary-field Monte Carlo approach to the Shell Model (AFMCSM), and preliminary applications exhibit a remarkable taming of the notorious sign problem. If the mitigation of the sign problem holds true, the AFMCSM will offer a method to compute quantum correlations to mean-field applications for just about all nuclei; giving exact results for CI model spaces that can approach 10{sup 20-25}. In these lectures, I will discuss modern applications of CI to the nuclear many-body problem that have the potential to guide nuclear structure theory into the next decade.

  1. SIMULATING ACCELERATOR STRUCTURE OPERATION AT HIGH POWER

    SciTech Connect

    Ivanov, V

    2004-09-15

    The important limiting factors in high-gradient accelerator structure operation are dark current capture, RF breakdown and electron multipacting. These processes involve both primary and secondary electron field emission and produce plasma and X-rays. To better understand these phenomena, they have simulated dark current generation and transport in a linac structure and a square-bend waveguide, both high power tested at SLAC. For these simulations, they use the parallel, time-domain, unstructured-grid code Tau3P and the particle tracking module Track3P. In this paper, they present numerical results and their comparison with measurements on energy spectrum of electrons transmitted in a 30-cell structure and of X-rays emitted from the square-bend waveguide.

  2. Stochastic Simulation Tool for Aerospace Structural Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F.; Moore, David F.

    2006-01-01

    Stochastic simulation refers to incorporating the effects of design tolerances and uncertainties into the design analysis model and then determining their influence on the design. A high-level evaluation of one such stochastic simulation tool, the MSC.Robust Design tool by MSC.Software Corporation, has been conducted. This stochastic simulation tool provides structural analysts with a tool to interrogate their structural design based on their mathematical description of the design problem using finite element analysis methods. This tool leverages the analyst's prior investment in finite element model development of a particular design. The original finite element model is treated as the baseline structural analysis model for the stochastic simulations that are to be performed. A Monte Carlo approach is used by MSC.Robust Design to determine the effects of scatter in design input variables on response output parameters. The tool was not designed to provide a probabilistic assessment, but to assist engineers in understanding cause and effect. It is driven by a graphical-user interface and retains the engineer-in-the-loop strategy for design evaluation and improvement. The application problem for the evaluation is chosen to be a two-dimensional shell finite element model of a Space Shuttle wing leading-edge panel under re-entry aerodynamic loading. MSC.Robust Design adds value to the analysis effort by rapidly being able to identify design input variables whose variability causes the most influence in response output parameters.

  3. Monte Carlo Simulation for LINAC Standoff Interrogation of Nuclear Material

    SciTech Connect

    Clarke, Shaun D; Flaska, Marek; Miller, Thomas Martin; Protopopescu, Vladimir A; Pozzi, Sara A

    2007-06-01

    The development of new techniques for the interrogation of shielded nuclear materials relies on the use of Monte Carlo codes to accurately simulate the entire system, including the interrogation source, the fissile target and the detection environment. The objective of this modeling effort is to develop analysis tools and methods-based on a relevant scenario-which may be applied to the design of future systems for active interrogation at a standoff. For the specific scenario considered here, the analysis will focus on providing the information needed to determine the type and optimum position of the detectors. This report describes the results of simulations for a detection system employing gamma rays to interrogate fissile and nonfissile targets. The simulations were performed using specialized versions of the codes MCNPX and MCNP-PoliMi. Both prompt neutron and gamma ray and delayed neutron fluxes have been mapped in three dimensions. The time dependence of the prompt neutrons in the system has also been characterized For this particular scenario, the flux maps generated with the Monte Carlo model indicate that the detectors should be placed approximately 50 cm behind the exit of the accelerator, 40 cm away from the vehicle, and 150 cm above the ground. This position minimizes the number of neutrons coming from the accelerator structure and also receives the maximum flux of prompt neutrons coming from the source. The lead shielding around the accelerator minimizes the gamma-ray background from the accelerator in this area. The number of delayed neutrons emitted from the target is approximately seven orders of magnitude less than the prompt neutrons emitted from the system. Therefore, in order to possibly detect the delayed neutrons, the detectors should be active only after all prompt neutrons have scattered out of the system. Preliminary results have shown this time to be greater than 5 ?s after the accelerator pulse. This type of system is illustrative of a

  4. Probabilistic simulation of uncertainties in thermal structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Shiao, Michael

    1990-01-01

    Development of probabilistic structural analysis methods for hot structures is a major activity at Lewis Research Center. It consists of five program elements: (1) probabilistic loads; (2) probabilistic finite element analysis; (3) probabilistic material behavior; (4) assessment of reliability and risk; and (5) probabilistic structural performance evaluation. Recent progress includes: (1) quantification of the effects of uncertainties for several variables on high pressure fuel turbopump (HPFT) blade temperature, pressure, and torque of the Space Shuttle Main Engine (SSME); (2) the evaluation of the cumulative distribution function for various structural response variables based on assumed uncertainties in primitive structural variables; (3) evaluation of the failure probability; (4) reliability and risk-cost assessment, and (5) an outline of an emerging approach for eventual hot structures certification. Collectively, the results demonstrate that the structural durability/reliability of hot structural components can be effectively evaluated in a formal probabilistic framework. In addition, the approach can be readily extended to computationally simulate certification of hot structures for aerospace environments.

  5. Material flow simulation in a nuclear chemical process

    SciTech Connect

    Mahgerefteh, M.

    1984-01-01

    At a nuclear fuel reprocessing plant the special nuclear materials (SNM) are received as constituents of spent fuel assemblies, are converted to liquid form, and undergo a series of chemical processes. Uncertainties in measurements of SNM at each stage of reprocessing limit the accuracy of simple material balance accounting as a safeguards method. To be effective, a formal safeguards program must take into account all sources of measurement error yet detect any diversion of SNM. An analytical method for assessing the accountability of selected constituent SNM is demonstrated. A combined discrete-continuous, time-dependent model using the GASP IV simulation language is developed to simulate mass flow, material accountability and measurement error at each stage of the reprocessing plant.

  6. Dynamic Simulation and Optimization of Nuclear Hydrogen Production Systems

    SciTech Connect

    Paul I. Barton; Mujid S. Kaximi; Georgios Bollas; Patricio Ramirez Munoz

    2009-07-31

    This project is part of a research effort to design a hydrogen plant and its interface with a nuclear reactor. This project developed a dynamic modeling, simulation and optimization environment for nuclear hydrogen production systems. A hybrid discrete/continuous model captures both the continuous dynamics of the nuclear plant, the hydrogen plant, and their interface, along with discrete events such as major upsets. This hybrid model makes us of accurate thermodynamic sub-models for the description of phase and reaction equilibria in the thermochemical reactor. Use of the detailed thermodynamic models will allow researchers to examine the process in detail and have confidence in the accurary of the property package they use.

  7. Nuclear Engine System Simulation (NESS) version 2.0

    NASA Astrophysics Data System (ADS)

    Pelaccio, Dennis G.; Scheil, Christine M.; Petrosky, Lyman J.

    The topics are presented in viewgraph form and include the following; nuclear thermal propulsion (NTP) engine system analysis program development; nuclear thermal propulsion engine analysis capability requirements; team resources used to support NESS development; expanded liquid engine simulations (ELES) computer model; ELES verification examples; NESS program development evolution; past NTP ELES analysis code modifications and verifications; general NTP engine system features modeled by NESS; representative NTP expander, gas generator, and bleed engine system cycles modeled by NESS; NESS program overview; NESS program flow logic; enabler (NERVA type) nuclear thermal rocket engine; prismatic fuel elements and supports; reactor fuel and support element parameters; reactor parameters as a function of thrust level; internal shield sizing; and reactor thermal model.

  8. Nuclear Engine System Simulation (NESS) version 2.0

    NASA Technical Reports Server (NTRS)

    Pelaccio, Dennis G.; Scheil, Christine M.; Petrosky, Lyman J.

    1993-01-01

    The topics are presented in viewgraph form and include the following; nuclear thermal propulsion (NTP) engine system analysis program development; nuclear thermal propulsion engine analysis capability requirements; team resources used to support NESS development; expanded liquid engine simulations (ELES) computer model; ELES verification examples; NESS program development evolution; past NTP ELES analysis code modifications and verifications; general NTP engine system features modeled by NESS; representative NTP expander, gas generator, and bleed engine system cycles modeled by NESS; NESS program overview; NESS program flow logic; enabler (NERVA type) nuclear thermal rocket engine; prismatic fuel elements and supports; reactor fuel and support element parameters; reactor parameters as a function of thrust level; internal shield sizing; and reactor thermal model.

  9. Simulation of the control board of an experimental nuclear reactor

    SciTech Connect

    Mackieh, A.; Cilingir, C.; Alten, S.

    1995-12-31

    This study is performed as a part of a bigger project to analyze human factors in operations of an experimental nuclear reactor. In this context, the control board of the 10-kW university training reactor (UTR-10) located at Iowa State University, Ames, Iowa, was simulated. The software was developed in the ergonomics laboratory of the Middle East Technical University (METU) by using an object-oriented programming language (Visual Basic for IBM-compatible personal computers).

  10. Simulation of plasma double-layer structures

    NASA Technical Reports Server (NTRS)

    Borovsky, J. E.; Joyce, G.

    1982-01-01

    Electrostatic plasma double layers are numerically simulated by means of a magnetized 2 1/2 dimensional particle in cell method. The investigation of planar double layers indicates that these one dimensional potential structures are susceptible to periodic disruption by instabilities in the low potential plasmas. Only a slight increase in the double layer thickness with an increase in its obliqueness to the magnetic field is observed. Weak magnetization results in the double layer electric field alignment of accelerated particles and strong magnetization results in their magnetic field alignment. The numerical simulations of spatially periodic two dimensional double layers also exhibit cyclical instability. A morphological invariance in two dimensional double layers with respect to the degree of magnetization implies that the potential structures scale with Debye lengths rather than with gyroradii. Electron beam excited electrostatic electron cyclotron waves and (ion beam driven) solitary waves are present in the plasmas adjacent to the double layers.

  11. Quantum simulations of nuclei and nuclear pasta with the multiresolution adaptive numerical environment for scientific simulations

    NASA Astrophysics Data System (ADS)

    Sagert, I.; Fann, G. I.; Fattoyev, F. J.; Postnikov, S.; Horowitz, C. J.

    2016-05-01

    Background: Neutron star and supernova matter at densities just below the nuclear matter saturation density is expected to form a lattice of exotic shapes. These so-called nuclear pasta phases are caused by Coulomb frustration. Their elastic and transport properties are believed to play an important role for thermal and magnetic field evolution, rotation, and oscillation of neutron stars. Furthermore, they can impact neutrino opacities in core-collapse supernovae. Purpose: In this work, we present proof-of-principle three-dimensional (3D) Skyrme Hartree-Fock (SHF) simulations of nuclear pasta with the Multi-resolution ADaptive Numerical Environment for Scientific Simulations (MADNESS). Methods: We perform benchmark studies of 16O, 208Pb, and 238U nuclear ground states and calculate binding energies via 3D SHF simulations. Results are compared with experimentally measured binding energies as well as with theoretically predicted values from an established SHF code. The nuclear pasta simulation is initialized in the so-called waffle geometry as obtained by the Indiana University Molecular Dynamics (IUMD) code. The size of the unit cell is 24 fm with an average density of about ρ =0.05 fm-3 , proton fraction of Yp=0.3 , and temperature of T =0 MeV. Results: Our calculations reproduce the binding energies and shapes of light and heavy nuclei with different geometries. For the pasta simulation, we find that the final geometry is very similar to the initial waffle state. We compare calculations with and without spin-orbit forces. We find that while subtle differences are present, the pasta phase remains in the waffle geometry. Conclusions: Within the MADNESS framework, we can successfully perform calculations of inhomogeneous nuclear matter. By using pasta configurations from IUMD it is possible to explore different geometries and test the impact of self-consistent calculations on the latter.

  12. Computational simulation of hot composite structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Murthy, P. L. N.; Singhal, S. N.

    1991-01-01

    Three different computer codes developed in-house are described for application to hot composite structures. These codes include capabilities for: (1) laminate behavior (METCAN); (2) thermal/structural analysis of hot structures made from high temperature metal matrix composites (HITCAN); and (3) laminate tailoring (MMLT). Results for select sample cases are described to demonstrate the versatility as well as the application of these codes to specific situations. The sample case results show that METCAN can be used to simulate cyclic life in high temperature metal matrix composites; HITCAN can be used to evaluate the structural performance of curved panels as well as respective sensitivities of various nonlinearities, and MMLT can be used to tailor the fabrication process in order to reduce residual stresses in the matrix upon cool-down.

  13. Computational simulation of hot composites structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Murthy, P. L. N.; Singhal, S. N.

    1991-01-01

    Three different computer codes developed in-house are described for application to hot composite structures. These codes include capabilities for: (1) laminate behavior (METCAN); (2) thermal/structural analysis of hot structures made from high temperature metal matrix composites (HITCAN); and (3) laminate tailoring (MMLT). Results for select sample cases are described to demonstrate the versatility as well as the application of these codes to specific situations. The sample case results show that METCAN can be used to simulate cyclic life in high temperature metal matrix composites; HITCAN can be used to evaluate the structural performance of curved panels as well as respective sensitivities of various nonlinearities, and MMLT can be used to tailor the fabrication process in order to reduce residual stresses in the matrix upon cool-down.

  14. An assessment of coupling algorithms for nuclear reactor core physics simulations

    NASA Astrophysics Data System (ADS)

    Hamilton, Steven; Berrill, Mark; Clarno, Kevin; Pawlowski, Roger; Toth, Alex; Kelley, C. T.; Evans, Thomas; Philip, Bobby

    2016-04-01

    This paper evaluates the performance of multiphysics coupling algorithms applied to a light water nuclear reactor core simulation. The simulation couples the k-eigenvalue form of the neutron transport equation with heat conduction and subchannel flow equations. We compare Picard iteration (block Gauss-Seidel) to Anderson acceleration and multiple variants of preconditioned Jacobian-free Newton-Krylov (JFNK). The performance of the methods are evaluated over a range of energy group structures and core power levels. A novel physics-based approximation to a Jacobian-vector product has been developed to mitigate the impact of expensive on-line cross section processing steps. Numerical simulations demonstrating the efficiency of JFNK and Anderson acceleration relative to standard Picard iteration are performed on a 3D model of a nuclear fuel assembly. Both criticality (k-eigenvalue) and critical boron search problems are considered.

  15. An assessment of coupling algorithms for nuclear reactor core physics simulations

    DOE PAGESBeta

    Hamilton, Steven; Berrill, Mark; Clarno, Kevin; Pawlowski, Roger; Toth, Alex; Kelley, C. T.; Evans, Thomas; Philip, Bobby

    2016-04-01

    Here we evaluate the performance of multiphysics coupling algorithms applied to a light water nuclear reactor core simulation. The simulation couples the k-eigenvalue form of the neutron transport equation with heat conduction and subchannel flow equations. We compare Picard iteration (block Gauss–Seidel) to Anderson acceleration and multiple variants of preconditioned Jacobian-free Newton–Krylov (JFNK). The performance of the methods are evaluated over a range of energy group structures and core power levels. A novel physics-based approximation to a Jacobian-vector product was developed to mitigate the impact of expensive on-line cross section processing steps. Numerical simulations demonstrating the efficiency of JFNK andmore » Anderson acceleration relative to standard Picard iteration are performed on a 3D model of a nuclear fuel assembly. Finally, both criticality (k-eigenvalue) and critical boron search problems are considered.« less

  16. Dynamic Deployment Simulations of Inflatable Space Structures

    NASA Technical Reports Server (NTRS)

    Wang, John T.

    2005-01-01

    The feasibility of using Control Volume (CV) method and the Arbitrary Lagrangian Eulerian (ALE) method in LSDYNA to simulate the dynamic deployment of inflatable space structures is investigated. The CV and ALE methods were used to predict the inflation deployments of three folded tube configurations. The CV method was found to be a simple and computationally efficient method that may be adequate for modeling slow inflation deployment sine the inertia of the inflation gas can be neglected. The ALE method was found to be very computationally intensive since it involves the solving of three conservative equations of fluid as well as dealing with complex fluid structure interactions.

  17. The TRIUMF nuclear structure program and TIGRESS

    SciTech Connect

    Garrett, P E; Andreyev, A; E.Austin, R A; Ball, G C; Bandyopadhyay, D; Becker, J A; Boston, A; Boston, H; Charkrawarthy, R S; Churchman, R; Cline, D; Cooper, R J; Cross, D; Dashdorj, D; Demand, G A; Dimmock, M R; Drake, T; Finlay, P; Gagnon, K; Gallant, A T; Green, K L; Grint, A N; Grinyer, G F; Hackman, G; Harkness, L J; Hayes, A B; Kanungo, R; Kulp, W D; Leach, K G; Lee, G; Leslie, J R; Maharaj, R; Martin, J P; Mattoon, C; Mills, W J; Morton, A C; Nelson, L; Newman, O; Nolan, P J; Padilla-Rodal, E; Pearson, C J; Phillips, A A; Porter-Peden, M; Ressler, J J; Ruiz, C; Sarazin, F; Schumaker, M A; Scraggs, D P; Strange, M T; Subramanian, M; Svensson, C E; Waddington, J C; Wan, J; Whitebeck, A; Williams, S J; Wood, J L; Wong, J C; Wu, C Y; Zganjar, E F

    2006-08-30

    The Isotope Separator and Accelerator (ISAC) facility located at the TRIUMF laboratory in Vancouver, Canada, is one of the world's most advanced ISOL-type radioactive ion beam facilities. An extensive {gamma}-ray spectroscopy program at ISAC is centered around two major research facilities: (1) the 8{pi} {gamma}-ray spectrometer for {beta}-delayed {gamma}-ray spectroscopy experiments with the low-energy beams from ISAC-I, and (2) the next-generation TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer (TIGRESS) for in-beam experiments with the accelerated radioactive ion beams. An overview of these facilities and recent results from the diverse program of nuclear structure and fundamental interaction studies they support is presented.

  18. Nuclear Reaction and Structure Databases of the National Nuclear Data Center

    SciTech Connect

    Pritychenko, B.; Arcilla, R.; Herman, M. W.; Oblozinsky, P.; Rochman, D.; Sonzogni, A. A.; Tuli, J. K.; Winchell, D. F.

    2006-03-13

    The National Nuclear Data Center (NNDC) collects, evaluates, and disseminates nuclear physics data for basic research and applied nuclear technologies. In 2004, the NNDC migrated all databases into modern relational database software, installed new generation of Linux servers and developed new Java-based Web service. This nuclear database development means much faster, more flexible and more convenient service to all users in the United States. These nuclear reaction and structure database developments as well as related Web services are briefly described.

  19. NUCLEAR STAR-FORMING RING OF THE MILKY WAY: SIMULATIONS

    SciTech Connect

    Kim, Sungsoo S.; Jeon, Myoungwon; Saitoh, Takayuki R.; Figer, Donald F.; Merritt, David; Wada, Keiichi

    2011-07-01

    We present hydrodynamic simulations of gas clouds in the central kpc region of the Milky Way that is modeled with a three-dimensional bar potential. Our simulations consider realistic gas cooling and heating, star formation, and supernova feedback. A ring of dense gas clouds forms as a result of X{sub 1}-X{sub 2} orbit transfer, and our potential model results in a ring radius of {approx}200 pc, which coincides with the extraordinary reservoir of dense molecular clouds in the inner bulge, the Central Molecular Zone (CMZ). The gas clouds accumulated in the CMZ can reach high enough densities to form stars, and with an appropriate choice of simulation parameters, we successfully reproduce the observed gas mass and the star formation rate (SFR) in the CMZ, {approx}2 x 10{sup 7} M{sub sun} and {approx}0.1 M{sub sun} yr{sup -1}. Star formation in our simulations takes place mostly in the outermost X{sub 2} orbits, and the SFR per unit surface area outside the CMZ is much lower. These facts suggest that the inner Galactic bulge may harbor a mild version of the nuclear star-forming rings seen in some external disk galaxies. Furthermore, from the relatively small size of the Milky Way's nuclear bulge, which is thought to be a result of sustained star formation in the CMZ, we infer that the Galactic inner bulge probably had a shallower density profile or stronger bar elongation in the past.

  20. Ab initio simulation of radiation damage in nuclear reactor pressure vessel materials

    NASA Astrophysics Data System (ADS)

    Watts, Daniel; Finkenstadt, Daniel

    2012-02-01

    Using Kinetic Monte Carlo we developed a code to study point defect hopping in BCC metallic alloys using energetics and attempt frequencies calculated using VASP, an electronic structure software package. Our code provides a way of simulating the effects of neutron radiation on potential reactor materials. Specifically we will compare the Molybdenum-Chromium alloy system to steel alloys for use in nuclear reactor pressure vessels.

  1. Experimental study of quantum simulation for quantum chemistry with a nuclear magnetic resonance simulator.

    PubMed

    Lu, Dawei; Xu, Nanyang; Xu, Boruo; Li, Zhaokai; Chen, Hongwei; Peng, Xinhua; Xu, Ruixue; Du, Jiangfeng

    2012-10-13

    Quantum computers have been proved to be able to mimic quantum systems efficiently in polynomial time. Quantum chemistry problems, such as static molecular energy calculations and dynamical chemical reaction simulations, become very intractable on classical computers with scaling up of the system. Therefore, quantum simulation is a feasible and effective approach to tackle quantum chemistry problems. Proof-of-principle experiments have been implemented on the calculation of the hydrogen molecular energies and one-dimensional chemical isomerization reaction dynamics using nuclear magnetic resonance systems. We conclude that quantum simulation will surpass classical computers for quantum chemistry in the near future. PMID:22946038

  2. Online Simulation of Radiation Track Structure Project

    NASA Technical Reports Server (NTRS)

    Plante, Ianik

    2015-01-01

    Space radiation comprises protons, helium and high charged and energy (HZE) particles. High-energy particles are a concern for human space flight, because they are no known options for shielding astronauts from them. When these ions interact with matter, they damage molecules and create radiolytic species. The pattern of energy deposition and positions of the radiolytic species, called radiation track structure, is highly dependent on the charge and energy of the ion. The radiolytic species damage biological molecules, which may lead to several long-term health effects such as cancer. Because of the importance of heavy ions, the radiation community is very interested in the interaction of HZE particles with DNA, notably with regards to the track structure. A desktop program named RITRACKS was developed to simulate radiation track structure. The goal of this project is to create a web interface to allow registered internal users to use RITRACKS remotely.

  3. Digital system for structural dynamics simulation

    NASA Technical Reports Server (NTRS)

    Krauter, A. I.; Lagace, L. J.; Wojnar, M. K.; Glor, C.

    1982-01-01

    State-of-the-art digital hardware and software for the simulation of complex structural dynamic interactions, such as those which occur in rotating structures (engine systems). System were incorporated in a designed to use an array of processors in which the computation for each physical subelement or functional subsystem would be assigned to a single specific processor in the simulator. These node processors are microprogrammed bit-slice microcomputers which function autonomously and can communicate with each other and a central control minicomputer over parallel digital lines. Inter-processor nearest neighbor communications busses pass the constants which represent physical constraints and boundary conditions. The node processors are connected to the six nearest neighbor node processors to simulate the actual physical interface of real substructures. Computer generated finite element mesh and force models can be developed with the aid of the central control minicomputer. The control computer also oversees the animation of a graphics display system, disk-based mass storage along with the individual processing elements.

  4. Nuclear Structure and Decay Data: Current Status and Future Perspectives

    SciTech Connect

    Kondev, Filip G.; Tuli, Jagdish K.

    2006-03-13

    The nuclear structure databases provide physicists around the world with a useful collection of reliable and well documented datasets. The Evaluated Nuclear Structure Data File (ENSDF) database, produced by the International Nuclear Structure and Decay Data Network (NSDD) under the auspices of the International Atomic Energy Agency (IAEA), contains evaluated experimental information for all known nuclei. The bibliographical database Nuclear Science References (NSR) provides references to published data in the field of Nuclear Physics. The Experimental Unevaluated Nuclear Data List (XUNDL) provides a method for rapid access to formatted (compiled) data from recently published articles. Detailed information regarding these databases, as well as other products and services, can be found at the National Nuclear Data Center (NNDC) and IAEA web portals.

  5. Investigations of nuclear structure and nuclear reactions induced by complex projectiles

    SciTech Connect

    Sarantites, D.G.

    1990-01-01

    This report discusses research in the following areas: nuclear structure; fusion reactions near and below the barrier; incomplete fusion and fragmentation reactions; and instrumentation and analysis. (LSP).

  6. Used nuclear fuel separations process simulation and testing

    SciTech Connect

    Pereira, C.; Krebs, J.F.; Copple, J.M.; Frey, K.E.; Maggos, L.E.; Figueroa, J.; Willit, J.L.; Papadias, D.D.

    2013-07-01

    Recent efforts in separations process simulation at Argonne have expanded from the traditional focus on solvent extraction flowsheet design in order to capture process dynamics and to simulate other components, processing and systems of a used nuclear fuel reprocessing plant. For example, the Argonne Model for Universal Solvent Extraction (AMUSE) code has been enhanced to make it both more portable and more readily extensible. Moving away from a spreadsheet environment makes the addition of new species and processes simpler for the expert user, which should enable more rapid implementation of chemical models that simulate evolving processes. The dyAMUSE (dynamic AMUSE) version allows the simulation of transient behavior across an extractor. Electrochemical separations have now been modeled using spreadsheet codes that simulate the electrochemical recycle of fast reactor fuel. The user can follow the evolution of the salt, products, and waste compositions in the electro-refiner, cathode processors, and drawdown as a function of fuel batches treated. To further expand capabilities in integrating multiple unit operations, a platform for linking mathematical models representing the different operations that comprise a reprocessing facility was adapted to enable systems-level analysis and optimization of facility functions. (authors)

  7. Upgrades to the NESS (Nuclear Engine System Simulation) Code

    NASA Technical Reports Server (NTRS)

    Fittje, James E.

    2007-01-01

    In support of the President's Vision for Space Exploration, the Nuclear Thermal Rocket (NTR) concept is being evaluated as a potential propulsion technology for human expeditions to the moon and Mars. The need for exceptional propulsion system performance in these missions has been documented in numerous studies, and was the primary focus of a considerable effort undertaken during the 1960's and 1970's. The NASA Glenn Research Center is leveraging this past NTR investment in their vehicle concepts and mission analysis studies with the aid of the Nuclear Engine System Simulation (NESS) code. This paper presents the additional capabilities and upgrades made to this code in order to perform higher fidelity NTR propulsion system analysis and design.

  8. Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Upgrade Activities

    NASA Technical Reports Server (NTRS)

    Emrich, William

    2013-01-01

    A key technology element in Nuclear Thermal Propulsion is the development of fuel materials and components which can withstand extremely high temperatures while being exposed to flowing hydrogen. NTREES provides a cost effective method for rapidly screening of candidate fuel components with regard to their viability for use in NTR systems. The NTREES is designed to mimic the conditions (minus the radiation) to which nuclear rocket fuel elements and other components would be subjected to during reactor operation. The NTREES consists of a water cooled ASME code stamped pressure vessel and its associated control hardware and instrumentation coupled with inductive heaters to simulate the heat provided by the fission process. The NTREES has been designed to safely allow hydrogen gas to be injected into internal flow passages of an inductively heated test article mounted in the chamber.

  9. Numerical simulation of shock interaction with above-ground structures

    NASA Astrophysics Data System (ADS)

    Baum, Joseph D.; Lohner, Rainald

    1994-05-01

    This final report for DNA contract DNA 001-89-C-0098 for the time period May 15, 1989 to Dec 31, 1992 describes the results of several of the computations conducted under this research effort. The numerical simulations conducted simulated shock wave diffraction phenomenon about complex-geometry two-dimensional and three-dimensional structures. Since a significant part of this effort was composed of parametric studies that have been delivered to the sponsors, the Defense Nuclear Agency and the Air Force Ballistic Missile Organization (BMO), and conducted under the now defunct Rail Garrison project, we included in this report a detailed description of the results of the major computations, and a brief summary of all the repetitive computations. The final report is divided into three sections. Chapter 1 describes in detail the two-dimensional numerical methodology and typical two-dimensional computation, i.e., the application of the numerical methodology to the simulation of shock interaction with a typical 2-D train (a 2-D cut at the center of a 3-D train). Chapter 2 describes the numerical development of a passive shock reflector, a major effort undertaken in this project. The objective of this effort was to design a passive device that, while allowing the ventilation of the enclosure under steady conditions, will prevent blast waves impinging on the wall from entering the enclosure when the structure is impacted by a shock.

  10. Using Direct Sub-Level Entity Access to Improve Nuclear Stockpile Simulation Modeling

    SciTech Connect

    Robert Y. Parker

    1999-08-01

    Direct sub-level entity access is a seldom-used technique in discrete-event simulation modeling that addresses the accessibility of sub-level entity information. The technique has significant advantages over more common, alternative modeling methods--especially where hierarchical entity structures are modeled. As such, direct sub-level entity access is often preferable in modeling nuclear stockpile, life-extension issues, an area to which it has not been previously applied. Current nuclear stockpile, life-extension models were demonstrated to benefit greatly from the advantages of direct sub-level entity access. In specific cases, the application of the technique resulted in models that were up to 10 times faster than functionally equivalent models where alternative techniques were applied. Furthermore, specific implementations of direct sub-level entity access were observed to be more flexible, efficient, functional, and scalable than corresponding implementations using common modeling techniques. Common modeling techniques (''unbatch/batch'' and ''attribute-copying'') proved inefficient and cumbersome in handling many nuclear stockpile modeling complexities, including multiple weapon sites, true defect analysis, and large numbers of weapon and subsystem types. While significant effort was required to enable direct sub-level entity access in the nuclear stockpile simulation models, the enhancements were worth the effort--resulting in more efficient, more capable, and more informative models that effectively addressed the complexities of the nuclear stockpile.

  11. Nuclear structure in the dinuclear model with rotating clusters

    SciTech Connect

    Adamian, G. G.; Antonenko, N. V.; Jolos, R. V.; Palchikov, Yu. V.; Shneidman, T. M.; Scheid, W.

    2007-08-15

    The dinuclear-system model can be applied to nuclear structure. Here, we study deformed clusters which rotate with respect to the internuclear distance and exchange nucleons. The model can be used to explain the band structure of nuclear spectra, especially the parity splitting observed in actinides, e.g., in {sup 238}U.

  12. Review of Methods Related to Assessing Human Performance in Nuclear Power Plant Control Room Simulations

    SciTech Connect

    Katya L Le Blanc; Ronald L Boring; David I Gertman

    2001-11-01

    With the increased use of digital systems in Nuclear Power Plant (NPP) control rooms comes a need to thoroughly understand the human performance issues associated with digital systems. A common way to evaluate human performance is to test operators and crews in NPP control room simulators. However, it is often challenging to characterize human performance in meaningful ways when measuring performance in NPP control room simulations. A review of the literature in NPP simulator studies reveals a variety of ways to measure human performance in NPP control room simulations including direct observation, automated computer logging, recordings from physiological equipment, self-report techniques, protocol analysis and structured debriefs, and application of model-based evaluation. These methods and the particular measures used are summarized and evaluated.

  13. SEYFERT GALAXIES: NUCLEAR RADIO STRUCTURE AND UNIFICATION

    SciTech Connect

    Lal, Dharam V.; Shastri, Prajval; Gabuzda, Denise C.

    2011-04-10

    A radio study of a carefully selected sample of 20 Seyfert galaxies that are matched in orientation-independent parameters, which are measures of intrinsic active galactic nucleus power and host galaxy properties, is presented to test the predictions of the unified scheme hypothesis. Our sample sources have core flux densities greater than 8 mJy at 5 GHz on arcsec scales due to the feasibility requirements. These simultaneous parsec-scale and kiloparsec-scale radio observations reveal (1) that Seyfert 1 and Seyfert 2 galaxies have an equal tendency to show compact radio structures on milliarcsecond scales, (2) the distributions of parsec-scale and kiloparsec-scale radio luminosities are similar for both Seyfert 1 and Seyfert 2 galaxies, (3) there is no evidence for relativistic beaming in Seyfert galaxies, (4) similar distributions of source spectral indices in spite of the fact that Seyferts show nuclear radio flux density variations, and (5) the distributions of the projected linear size for Seyfert 1 and Seyfert 2 galaxies are not significantly different as would be expected in the unified scheme. The latter could be mainly due to a relatively large spread in the intrinsic sizes. We also find that a starburst alone cannot power these radio sources. Finally, an analysis of the kiloparsec-scale radio properties of the CfA Seyfert galaxy sample shows results consistent with the predictions of the unified scheme.

  14. Structural integrity of nuclear reactor pressure vessels

    NASA Astrophysics Data System (ADS)

    Knott, John F.

    2013-09-01

    The paper starts from concerns expressed by Sir Alan Cottrell, in the early 1970s, related to the safety of the pressurized water reactor (PWR) proposed at that time for the next phase of electrical power generation. It proceeds to describe the design and operation of nuclear generation plant and gives details of the manufacture of PWR reactor pressure vessels (RPVs). Attention is paid to stress-relief cracking and under-clad cracking, experienced with early RPVs, explaining the mechanisms for these forms of cracking and the means taken to avoid them. Particular note is made of the contribution of non-destructive inspection to structural integrity. Factors affecting brittle fracture in RPV steels are described: in particular, effects of neutron irradiation. The use of fracture mechanics to assess defect tolerance is explained, together with the failure assessment diagram embodied in the R6 procedure. There is discussion of the Master Curve and how it incorporates effects of irradiation on fracture toughness. Dangers associated with extrapolation of data to low probabilities are illustrated. The treatment of fatigue-crack growth is described, in the context of transients that may be experienced in the operation of PWR plant. Detailed attention is paid to the thermal shock associated with a large loss-of-coolant accident. The final section reviews the arguments advanced to justify 'Incredibility of Failure' and how these are incorporated in assessments of the integrity of existing plant and proposed 'new build' PWR pressure vessels.

  15. Nuclear power plant simulators: their use in operator training and requalification

    SciTech Connect

    Jones, D.W.; Baer, D.K.; Francis, C.C.

    1980-07-01

    This report presents the results of a study performed for the Nuclear Regulatory Commission to evaluate the capabilities and use of nuclear power plant simulators either built or being built by the US nuclear power industry; to determine the adequacy of existing standards for simulator design and for the training of power plant operators on simulators; and to assess the issues about simulator training programs raised by the March 28, 1979, accident at Three Mile Island Unit 2.

  16. Many-Body Interactions and Nuclear Structure

    SciTech Connect

    Hjorth-Jensen, M.; Dean, David Jarvis; Hagen, Gaute; Kvaal, S.

    2010-01-01

    This article presents several challenges to nuclear many-body theory and our understanding of the stability of nuclear matter. In order to achieve this, we present five different cases, starting with an idealized toy model. These cases expose problems that need to be understood in order to match recent advances in nuclear theory with current experimental programs in low-energy nuclear physics. In particular, we focus on our current understanding, or lack thereof, of many-body forces, and how they evolve as functions of the number of particles. We provide examples of discrepancies between theory and experiment and outline some selected perspectives for future research directions.

  17. Simulated antineutrino signatures of nuclear reactors for nonproliferation applications

    NASA Astrophysics Data System (ADS)

    Misner, Alex C.

    2008-10-01

    Antineutrino detectors could provide a valuable addition to current safeguards regimes. Antineutrinos are an attractive emission to monitor due to their low interaction cross-section that prevents them from being shielded and the dependence of their spectrum on the power level and isotopic content of a reactor core. While there are antineutrino detectors currently deployed at an operational reactor, such observations cannot predict the effect of the diversion of nuclear material on the antineutrino emissions. Utilizing simulation tools, one can predict the antineutrino signatures of such abnormal operations and other reactor types that have not been experimentally measured. This study simulates reactor cores with assembly-level resolution for both baseline and diversion cases in order to predict the properties of a detector for measuring the differences in the antineutrino signatures.

  18. Simulations of kinetically irreversible protein aggregate structure.

    PubMed Central

    Patro, S Y; Przybycien, T M

    1994-01-01

    We have simulated the structure of kinetically irreversible protein aggregates in two-dimensional space using a lattice-based Monte-Carlo routine. Our model specifically accounts for the intermolecular interactions between hydrophobic and hydrophilic protein surfaces and a polar solvent. The simulations provide information about the aggregate density, the types of inter-monomer contacts and solvent content within the aggregates, the type and extent of solvent exposed perimeter, and the short- and long-range order all as a function of (i) the extent of monomer hydrophobic surface area and its distribution on the model protein surface and (ii) the magnitude of the hydrophobic-hydrophobic contact energy. An increase in the extent of monomer hydrophobic surface area resulted in increased aggregate densities with concomitant decreased system free energies. These effects are accompanied by increases in the number of hydrophobic-hydrophobic contacts and decreases in the solvent-exposed hydrophobic surface area of the aggregates. Grouping monomer hydrophobic surfaces in a single contiguous stretch resulted in lower aggregate densities and lower short range order. More favorable hydrophobic-hydrophobic contact energies produced structures with higher densities but the number of unfavorable protein-protein contacts was also observed to increase; greater configurational entropy produced the opposite effect. Properties predicted by our model are in good qualitative agreement with available experimental observations. Images FIGURE 6 FIGURE 13 PMID:8061184

  19. Simulation modeling of nuclear steam generator water level process--a case study

    PubMed

    Zhao; Ou; Du

    2000-01-01

    Simulation modeling of the nuclear steam generator (SG) water level process in Qinshan Nuclear Power Plant (QNPP) is described in this paper. A practical methodology was adopted so that the model is both simple and accurate for control engineering implementation. The structure of the model is in the form of a transfer function, which was determined based on first-principles analysis and expert experience. The parameters of the model were obtained by taking advantage of the recorded historical response curves under the existing closed-loop control system. The results of process dimensional data verification and experimental tests demonstrate that the simulation model depicts the main dynamic characteristics of the SG water level process and is in accordance with the field recorded response curves. The model has been successfully applied to the design and test of an advanced digital feedwater control system in QNPP. PMID:10871210

  20. Nuclear winter - Three-dimensional simulations including interactive transport, scavenging, and solar heating of smoke

    NASA Technical Reports Server (NTRS)

    Malone, R. C.; Auer, L. H.; Glatzmaier, G. A.; Wood, M. C.; Toon, O. B.

    1986-01-01

    A reexamination is conducted of the 'nuclear winter' hypothesis with a three-dimensional global model modified to allow for localized injection of smoke, its transport by the simulated winds, its absorption of sunlight, and its removal by model-simulated precipitation. Smoke injected into the troposphere is driven upward by solar heating. The tropopause, initially above the smoke, reforms below the heat smoke layer and separates it from precipitation below. Although much smoke is scavenged while the thermal structure is being altered, the residence time of the remaining smoke is greatly increased. Particularly for July conditions, a longer-lasting 'nuclear winter' effect is observed than was found in earlier modeling studies in which normal tropospheric residence times were assumed. In January the smaller solar flux in the northern hemisphere allows faster removal of smoke than in July. Significant cooling of the northern hemisphere continents is predicted; its dependence on season and injected smoke mass is described.

  1. Multiscale Simulation of Microbe Structure and Dynamics

    PubMed Central

    Joshi, Harshad; Singharoy, Abhishek; Sereda, Yuriy V.; Cheluvaraja, Srinath C.; Ortoleva, Peter J.

    2012-01-01

    A multiscale mathematical and computational approach is developed that captures the hierarchical organization of a microbe. It is found that a natural perspective for understanding a microbe is in terms of a hierarchy of variables at various levels of resolution. This hierarchy starts with the N -atom description and terminates with order parameters characterizing a whole microbe. This conceptual framework is used to guide the analysis of the Liouville equation for the probability density of the positions and momenta of the N atoms constituting the microbe and its environment. Using multiscale mathematical techniques, we derive equations for the co-evolution of the order parameters and the probability density of the N-atom state. This approach yields a rigorous way to transfer information between variables on different space-time scales. It elucidates the interplay between equilibrium and far-from-equilibrium processes underlying microbial behavior. It also provides framework for using coarse-grained nanocharacterization data to guide microbial simulation. It enables a methodical search for free-energy minimizing structures, many of which are typically supported by the set of macromolecules and membranes constituting a given microbe. This suite of capabilities provides a natural framework for arriving at a fundamental understanding of microbial behavior, the analysis of nanocharacterization data, and the computer-aided design of nanostructures for biotechnical and medical purposes. Selected features of the methodology are demonstrated using our multiscale bionanosystem simulator DeductiveMultiscaleSimulator. Systems used to demonstrate the approach are structural transitions in the cowpea chlorotic mosaic virus, RNA of satellite tobacco mosaic virus, virus-like particles related to human papillomavirus, and iron-binding protein lactoferrin. PMID:21802438

  2. Integrated Radiation Transport and Nuclear Fuel Performance for Assembly-Level Simulations

    SciTech Connect

    Clarno, Kevin T; Hamilton, Steven P; Philip, Bobby; Berrill, Mark A; Sampath, Rahul S; Allu, Srikanth; Pugmire, Dave; Dilts, Gary; Banfield, James E

    2012-02-01

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step toward incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source-terms and boundary conditions of traditional (single-pin) nuclear fuel performance simulation, such as the neutron flux distribution, coolant conditions, and assembly mechanical stresses. A novel scheme is introduced for transferring the power distribution from the Scale/Denovo (Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy. In addition, a new nuclear fuel-specific preconditioner was developed to account for the high aspect ratio of each fuel pin (12 feet axially, but 1 4 inches in diameter) with many individual fuel regions (pellets). With this novel capability, AMPFuel was used to model an entire 17 17 pressurized water reactor fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics), including the fuel, gap, and cladding of each of the 264 fuel pins; the 25 guide tubes; the top and bottom structural regions; and the upper and lower (neutron) reflector regions. The final, full assembly calculation was executed on Jaguar using 40,000 cores in under 10 hours to model over 162

  3. THIEF: An interactive simulation of nuclear materials safeguards

    SciTech Connect

    Stanbro, W. D.

    1990-01-01

    The safeguards community is facing an era in which it will be called upon to tighten protection of nuclear material. At the same time, it is probable that safeguards will face more competition for available resources from other activities such as environmental cleanup. To exist in this era, it will be necessary to understand and coordinate all aspects of the safeguards system. Because of the complexity of the interactions involved, this process puts a severe burden on designers and operators of safeguards systems. This paper presents a simulation tool developed at the Los Alamos National Laboratory to allow users to examine the interactions among safeguards elements as they apply to combating the insider threat. The tool consists of a microcomputer-based simulation in which the user takes the role of the insider trying to remove nuclear material from a facility. The safeguards system is run by the computer and consists of both physical protection and MC A computer elements. All data elements describing a scenario can be altered by the user. The program can aid in training, as well as in developing threat scenarios. 4 refs.

  4. Interactive Simulation of Nuclear Materials Safeguards and Security

    Energy Science and Technology Software Center (ESTSC)

    1994-03-14

    THIEF is an interactive computer simulation or computer game of the safeguards and security (S&S) systems of a nuclear facility. The user is placed in the role of a non-violent insider attempting to remove special nuclear material from the facility. All portions of the S&S system that are relevant to the non-violent insider threat are included. The computer operates the S&S systems and attempts to detect the loss of the nuclear material. Both the physicalmore » protection system and the materials control and accounting system are modeled. The description of the facility and its S&S systems are defined by the user with the aid of an input module. All aspects of the facility description are provided by the user. The program has a custom graphical user interface to facilitate its use by people with limited computer experience. The custom interface also allows it to run on relatively small computer systems.« less

  5. Finite Element Simulation of Smart Structures

    NASA Technical Reports Server (NTRS)

    Cui, Y. Lawrence; Panahandeh, M.

    1996-01-01

    Finite element equations representing the behavior of piezoelectric materials when bounded to a typical structure and used as sensors and actuators were developed. Emphasis was placed on generating sensor output equations of piezoelectric sensors and responses of a typical structure bonded with piezoelectric sensors and actuators on the basis of finite element formulation. The model can predict not only structural responses due to both mechanical and electrical loading but also electrical potential due to mechanical or thermal effects. The resulted finite element equations were then used for simple control design and performance evaluation. In the control algorithm, voltages coming out from piezoelectric sensors, which are proportional to strains at sensing locations, are taken as input. The voltages applied to the piezoelectric actuators are used as output. The feasibility of integrating control algorithm with the element routine developed herein and FEAP was demonstrated. In particular, optimal independent modal space control was implemented in a software package on the basis of finite element formulation. A rudimentary finite element-control algorithm package was also developed to evaluate the performance of candidate control laws. A few numerical simulations using the software package developed herein were given. The integrated software package will provide a design tool to address issues such as how adaptive smart systems will scale to a full size aircraft, the amount of piezoelectric materials and the powers needed to actuate it for desired performance. It will also provide a viable new structural control design concept for practical applications in large flexible structures such as aerospace vehicles and aircraft.

  6. Nudat: Nuclear Structure and Decay Data from the National Nuclear Data Center (NNDC)

    DOE Data Explorer

    NuDat allows users to search and plot nuclear structure and decay data interactively. NuDat was developed by the National Nuclear Data Center (NNDC)but utilizes contributions from physicists around the world. It provides an interface between web users and several databases containing nuclear structure, nuclear decay and some neutron-induced nuclear reaction information. Users can search for nuclear level properties (energy, half-life, spinparity), gamma-ray information (energy, intensity, multipolarity, coincidences), radiation information following nuclear decay (energy, intensity, dose), and neutron-induced reaction data from the BNL-325 book (thermal cross section and resonance integral). The information provided by NuDat 2 can be viewed in tables, level schemes and an interactive chart of nuclides.

  7. Crashworthiness simulation of composite automotive structures

    SciTech Connect

    Botkin, M E; Johnson, N L; Simunovic, S; Zywicz, E

    1998-06-01

    In 1990 the Automotive Composites Consortium (ACC) began the investigation of crash worthiness simulation methods for composite materials. A contract was given to Livermore Software Technology Corporation (LSTC) to implement a new damage model in LS-DYNA3DTM specifically for composite structures. This model is in LS-DYNA3DTM and is in use by the ACC partners. In 1994 USCAR, a partnership of American auto companies, entered into a partnership called SCAAP (Super Computing Automotive Applications Partnership) for the express purpose of working with the National Labs on computational oriented research. A CRADA (Cooperative Research and Development Agreement) was signed with Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, Sandia National Laboratory, Argonne National Laboratory, and Los Alamos National Laboratory to work in three distinctly different technical areas, one of which was composites material modeling for crash worthiness. Each Laboratory was assigned a specific modeling task. The ACC was responsible for the technical direction of the composites project and provided all test data for code verification. All new models were to be implemented in DYNA3D and periodically distributed to all partners for testing. Several new models have been developed and implemented. Excellent agreement has been shown between tube crush simulation and experiments.

  8. PREFACE: Open Problems in Nuclear Structure Theory: Introduction Open Problems in Nuclear Structure Theory: Introduction

    NASA Astrophysics Data System (ADS)

    Dobaczewski, Jacek

    2010-06-01

    Nuclear structure theory is a domain of physics faced at present with great challenges and opportunities. A larger and larger body of high-precision experimental data has been and continues to be accumulated. Experiments on very exotic short-lived isotopes are the backbone of activity at numerous large-scale facilities. Over the years, tremendous progress has been made in understanding the basic features of nuclei. However, the theoretical description of nuclear systems is still far from being complete and is often not very precise. Many questions, both basic and practical, remain unanswered. The goal of publishing this special focus issue of Journal of Physics G: Nuclear and Particle Physics on Open Problems in Nuclear Structure Theory (OPeNST) is to construct a fundamental inventory thereof, so that the tasks and available options become more clearly exposed and that this will help to stimulate a boost in theoretical activity, commensurate with the experimental progress. The requested format and scope of the articles on OPeNST was quite flexible. The journal simply offered the possibility to provide a forum for the material, which is very often discussed at conferences during the coffee breaks but does not normally have sufficient substance to form regular publications. Nonetheless, very often formulating a problem provides a major step towards its solution, and it may constitute a scientific achievement on its own. Prospective authors were therefore invited to find their own balance between the two extremes of very general problems on the one hand (for example, to solve exactly the many-body equations for a hundred particles) and very specific problems on the other hand (for example, those that one could put in one's own grant proposal). The authors were also asked not to cover results already obtained, nor to limit their presentations to giving a review of the subject, although some elements of those could be included to properly introduce the subject matter

  9. Mechanical regulation of nuclear structure and function.

    PubMed

    Martins, Rui P; Finan, John D; Guilak, Farshid; Lee, David A

    2012-01-01

    Mechanical loading induces both nuclear distortion and alterations in gene expression in a variety of cell types. Mechanotransduction is the process by which extracellular mechanical forces can activate a number of well-studied cytoplasmic signaling cascades. Inevitably, such signals are transduced to the nucleus and induce transcription factor-mediated changes in gene expression. However, gene expression also can be regulated through alterations in nuclear architecture, providing direct control of genome function. One putative transduction mechanism for this phenomenon involves alterations in nuclear architecture that result from the mechanical perturbation of the cell. This perturbation is associated with direct mechanical strain or osmotic stress, which is transferred to the nucleus. This review describes the current state of knowledge relating the nuclear architecture and the transfer of mechanical forces to the nucleus mediated by the cytoskeleton, the nucleoskeleton, and the LINC (linker of the nucleoskeleton and cytoskeleton) complex. Moreover, remodeling of the nucleus induces alterations in nuclear stiffness, which may be associated with cell differentiation. These phenomena are discussed in relation to the potential influence of nuclear architecture-mediated mechanoregulation of transcription and cell fate. PMID:22655599

  10. Forging the link between nuclear reactions and nuclear structure.

    PubMed

    Mahzoon, M H; Charity, R J; Dickhoff, W H; Dussan, H; Waldecker, S J

    2014-04-25

    A comprehensive description of all single-particle properties associated with the nucleus Ca40 is generated by employing a nonlocal dispersive optical potential capable of simultaneously reproducing all relevant data above and below the Fermi energy. The introduction of nonlocality in the absorptive potentials yields equivalent elastic differential cross sections as compared to local versions but changes the absorption profile as a function of angular momentum suggesting important consequences for the analysis of nuclear reactions. Below the Fermi energy, nonlocality is essential to allow for an accurate representation of particle number and the nuclear charge density. Spectral properties implied by (e, e'p) and (p, 2p) reactions are correctly incorporated, including the energy distribution of about 10% high-momentum nucleons, as experimentally determined by data from Jefferson Lab. These high-momentum nucleons provide a substantial contribution to the energy of the ground state, indicating a residual attractive contribution from higher-body interactions for Ca40 of about 0.64  MeV/A. PMID:24815643

  11. Nuclear shell structures in terms of classical periodic orbits

    NASA Astrophysics Data System (ADS)

    Arita, Ken-ichiro

    2016-06-01

    Semiclassical periodic-orbit theory (POT) theory is applied to the physics of nuclear structures, with the use of a realistic nuclear mean-field model given by the radial power-law potential. Evolution of deformed shell structures, which are responsible for various nuclear deformations, are clearly understood from the contribution of short classical periodic orbits (POs). Bifurcations of short POs, which imply underlying local dynamical symmetry, play significant role there. The effect of the spin degree of freedom is also investigated in relevance to the pseudospin symmetry in spherical nuclei and the prolate–oblate asymmetry in shell structures of nuclei with quadrupole-type deformations.

  12. Procedures manual for the Evaluated Nuclear Structure Data File

    SciTech Connect

    Bhat, M.R.

    1987-10-01

    This manual is a collection of various notes, memoranda and instructions on procedures for the evaluation of data in the Evaluated Nuclear Structure Data File (ENSDF). They were distributed at different times over the past few years to the evaluators of nuclear structure data and some of them were not readily avaialble. Hence, they have been collected in this manual for ease of reference by the evaluators of the international Nuclear Structure and Decay Data (NSDD) network contribute mass-chains to the ENSDF. Some new articles were written specifically for this manual and others are reivsions of earlier versions.

  13. HST imaging of nearby CSOs: obscuration and nuclear structures

    NASA Astrophysics Data System (ADS)

    Perlman, E. S.; Stocke, J. T.; Conway, J. E.; Reynolds, C.; Begelman, M.

    2002-05-01

    We present 3-band HST imaging of three nearby ( z<0.1) compact symmetric objects: 4C31.04, 1946+708 and 1146+596 (NGC 3894). These objects were chosen for HST observation on the basis of detected HI and molecular line absorption. The images show large amounts of obscuration in each source, well distributed throughout the host galaxies, but somewhat concentrated in the nuclear regions. All three also show evidence of nuclear structures which resemble disks or tori. We discuss the possible association of the nuclear structures and obscuration with their radio structures, and compare with other HST observations of GPS, CSS and large-scale radio galaxies.

  14. Structural performance of HEPA filters under simulated tornado conditions

    SciTech Connect

    Horak, H.L.; Gregory, W.S.; Ricketts, C.I.; Smith, P.R.

    1982-02-01

    This report contains the results of structural tests to determine the response of High Efficiency Particulate Air filters to simulated tornado conditions. The data include the structural limits of the filters, their resistance at high flow rates, and the effects of filter design features and tornado parameters. Considering all the filters tested, the mean break pressure or structural limit was found to be 2.35 pse (16.2 kPa). The maximum value was 2.87 psi (19.8 kPa), and the low value found was 1.31 psi (9.0 kPa). The type of failure was usually a medium break of the downstream filter fold. The type of filters that were evaluated were nuclear grade with design flow rates of 1000 cfm (0.472 m/sup 3//s), standard separators, and folded medium design. The parameters evaluated that are characteristic of the filter included manufacturer, separator type, faceguards, pack tightness, and aerosol loading. Manufacturer and medium properties were found to have a large effect on the structural limits.

  15. Mechanistic Insights from Structural Analyses of Ran-GTPase-Driven Nuclear Export of Proteins and RNAs.

    PubMed

    Matsuura, Yoshiyuki

    2016-05-22

    Understanding how macromolecules are rapidly exchanged between the nucleus and the cytoplasm through nuclear pore complexes is a fundamental problem in biology. Exportins are Ran-GTPase-dependent nuclear transport factors that belong to the karyopherin-β family and mediate nuclear export of a plethora of proteins and RNAs, except for bulk mRNA nuclear export. Exportins bind cargo macromolecules in a Ran-GTP-dependent manner in the nucleus, forming exportin-cargo-Ran-GTP complexes (nuclear export complexes). Transient weak interactions between exportins and nucleoporins containing characteristic FG (phenylalanine-glycine) repeat motifs facilitate nuclear pore complex passage of nuclear export complexes. In the cytoplasm, nuclear export complexes are disassembled, thereby releasing the cargo. GTP hydrolysis by Ran promoted in the cytoplasm makes the disassembly reaction virtually irreversible and provides thermodynamic driving force for the overall export reaction. In the past decade, X-ray crystallography of some of the exportins in various functional states coupled with functional analyses, single-particle electron microscopy, molecular dynamics simulations, and small-angle solution X-ray scattering has provided rich insights into the mechanism of cargo binding and release and also begins to elucidate how exportins interact with the FG repeat motifs. The knowledge gained from structural analyses of nuclear export is being translated into development of clinically useful inhibitors of nuclear export to treat human diseases such as cancer and influenza. PMID:26519791

  16. Neutron Correlations in Special Nuclear Materials, Experiments and Simulations

    SciTech Connect

    Verbeke, J; Dougan, A; Nakae, L; Sale, K; Snyderman, N

    2007-06-05

    Fissile materials emit neutrons with an unmistakable signature that can reveal characteristics of the material. We describe here measurements, simulations, and predicted signals expected and prospects for application of neutron correlation measurement methods to detection of special nuclear materials (SNM). The occurrence of fission chains in SNM can give rise to this distinctive, measurable time correlation signal. The neutron signals can be analyzed to detect the presence and to infer attributes of the SNM and surrounding materials. For instance, it is possible to infer attributes of an assembly containing a few kilograms of uranium, purely passively, using detectors of modest size in a reasonable time. Neutron signals of three radioactive sources are shown to illustrate the neutron correlation and analysis method. Measurements are compared with Monte Carlo calculations of the authenticated sources.

  17. High temperature dilatometry of simulated oxide nuclear fuel

    NASA Astrophysics Data System (ADS)

    Tenishev, A. V.; Baranov, V. G.; Kuzmin, R. S.; Pokrovskiy, S. A.

    2016-04-01

    High temperature dilatometry of model systems based on uranium dioxide with additives of burnable neutron absorbers both as Gd2O3 and as AlGdO3, and fission products simulators (FPS) was performed. It shown that in some cases instead of high temperature samples shrinkage there is a sharp transition to the expansion, which is associated with an increase of the samples volume due to the formation of liquid phases. The beginning of a complex composition eutectic melting starts at temperatures from 1950 to 2250 °C in the uranium dioxide samples containing significant amounts of Al, Gd, and FPS. Thus, in the analysis of oxide nuclear fuel behavior at high temperatures should be considered that the formation of liquid phases is possible at a temperature of 1000 °C lower than a melting point of pure stoichiometric uranium dioxide if its initial composition became more complex.

  18. Chavir: Virtual reality simulation for interventions in nuclear installations

    SciTech Connect

    Thevenon, J. B.; Tirel, O.; Lopez, L.; Chodorge, L.; Desbats, P.

    2006-07-01

    Companies involved in the nuclear industry have to prepare for interventions by precisely analyzing the radiological risks and rapidly evaluating the consequences of their operational choices. They also need to consolidate the experiences gained in the field with greater responsiveness and lower costs. This paper brings out the advantages of using virtual reality technology to meet the demands in the industry. The CHAVIR software allows the operators to prepare (and repeat) all the operations they would have to do in a safe virtual world, before performing the actual work inside the facilities. Since the decommissioning or maintenance work is carried out in an environment where there is radiation, the amount of radiation that the operator would be exposed to is calculated and integrated into the simulator. (authors)

  19. Chemical durability of simulated nuclear glasses containing water

    SciTech Connect

    Li, H.; Tomozawa, M.

    1995-04-01

    The chemical durability of simulated nuclear waste glasses having different water contents was studied. Results from the product consistency test (PCT) showed that glass dissolution increased with water content in the glass. This trend was not observed during MCC-1 testing. This difference was attributed to the differences in reactions between glass and water. In the PCT, the glass network dissolution controlled the elemental releases, and water in the glass accelerated the reaction rate. On the other hand, alkali ion exchange with hydronium played an important role in the MCC-1. For the latter, the amount of water introduced into a leached layer from ion-exchange was found to be much greater than that of initially incorporated water in the glass. Hence, the initial water content has no effect on glass dissolution as measured by the MCC-1 test.

  20. [Electromagnetic studies of nuclear structure and reactions]. Progress summary

    SciTech Connect

    Not Available

    1992-12-31

    The experimental goals are focused on developing an understanding of strong interactions and the structure of hadronic systems by determination of the electromagnetic response; these goals will be accomplished through coincidence detection of final states. Nuclear modeling objectives are to organize and interpret the data through a consistent description of a broad spectrum of reaction observables; calculations are performed in a nonrelativistic diagrammatic framework as well as a relativistic QHD approach. Work is described according to the following arrangement: direct knockout reactions (completion of {sup 16}O(e,e{prime}p), {sup 12}C(e,e{prime}pp) progress, large acceptance detector physics simulations), giant resonance studies (intermediate-energy experiments with solid-state detectors, the third response function in {sup 12}C(e,e{prime}p{sub 0}) and {sup 16}O(e,e{prime}p{sub 0}), comparison of the {sup 12}C(e, e{prime}p{sub 0}) and {sup 16}O(e,e{prime}p{sub 3}) reactions, quadrupole strength in the {sup 16}O(e,e{prime}{alpha}{sub 0}) reaction, quadrupole strength in the {sup 12}C(e,e{prime}{alpha}) reaction, analysis of the {sup 12}C(e,e{prime}p{sub 1}) and {sup 16}O(e,e{prime}p{sub 3}) angular distributions, analysis of the {sup 40}Ca(e,e{prime}x) reaction at low q, analysis of the higher-q {sup 12}C(e,e{prime}x) data from Bates), models of nuclear structure (experimental work, Hartree-Fock calculations, phonon excitations in spherical nuclei, shell model calculations, variational methods for relativistic fields), and instrumentation development efforts (developments at CEBAF, CLAS contracts, BLAST developments).

  1. Simulating the venting of radioactivity from a soviet nuclear test

    NASA Astrophysics Data System (ADS)

    Rodriguez, Daniel J.; Peterson, Kendall R.

    Fresh fission products were found in several routine air samples in Europe during the second and third weeks of March 1987. Initially, it was suspected that the radionuclides, principally 133Xe and 131I, had been accidentally released from a European facility handling nuclear materials. However, the announcement of an underground nuclear test at Semipalatinsk, U.S.S.R. on 26 February 1987 suggested that the elevated amounts of radioactivity may, instead, have been caused by a venting episode. Upon learning of these events, we simulated the transport and diffusion of 133Xe with our Hemispheric MEDIC and ADPIC models, assuming Semipalatinsk to be the source of the radioactive emissions. The correspondence between the calculated concentrations and the daily average 133Xe measurements made by the Federal Office for Civil Protection in F.R.G. was excellent. While this agreement does not, in itself, prove that an atmospheric venting of radioactive material occurred at Semipalatinsk, a body of circumstantial evidence exists which, when added together, strongly supports this conclusion. Our calculations suggested a total fission yield of about 40 kt, which is within the 20-150 kt range of tests acknowledged by the U.S.S.R. Finally, dose calculations indicated that no health or environmental impact occurred outside of the U.S.S.R. due to the suspected venting of 133Xe. However, the inhalation dose resulting from 133I, an unmodeled component of the radioactive cloud, represented a greater potential risk to public health.

  2. Nuclear structure notes on element 115 decay chains

    SciTech Connect

    Rudolph, D. Sarmiento, L. G.; Forsberg, U.

    2015-10-15

    Hitherto collected data on more than hundred α-decay chains stemming from element 115 are combined to probe some aspects of the underlying nuclear structure of the heaviest atomic nuclei yet created in the laboratory.

  3. Stress Management and Nuclear Anxiety: A Structured Group Experience.

    ERIC Educational Resources Information Center

    Bisio, Thomas A.; Crisan, Pamela

    1984-01-01

    Describes a structured workshop in which group members explore their fears of nuclear holocaust and the effects this fear has had on their lives. By using logotherapy ideals, the participants create a renewed sense of purpose and hope. (Author)

  4. HMG Nuclear Proteins: Linking Chromatin Structure to Cellular Phenotype

    PubMed Central

    Reeves, Raymond

    2009-01-01

    I. Summary Although the three families of mammalian HMG proteins (HMGA, HMGB and HMGN) participate in many of the same nuclear processes, each family plays its own unique role in modulating chromatin structure and regulating genomic function. This review focuses on the similarities and differences in the mechanisms by which the different HMG families impact chromatin structure and influence cellular phenotype. The biological implications of having three architectural transcription factor families with complementary, but partially overlapping, nuclear functions are discussed. PMID:19748605

  5. Hierarchical structure for risk criteria applicable to nuclear power plants

    SciTech Connect

    Hall, R.E.; Mitra, S.P.

    1985-01-01

    This paper discusses the development of a hierarchical structure for risk criteria applicable to nuclear power plants. The structure provides a unified framework to systematically analyze the implications of different types of criteria, each focusing on a particular aspect of nuclear power plant risks. The framework allows investigation of the specific coverage of a particular criterion and comparison of different criteria with regard to areas to which they apply. 5 refs., 2 figs.

  6. EVALUATED NUCLEAR STRUCTURE DATA FILE AND RELATED PRODUCTS.

    SciTech Connect

    TULI,J.K.

    2004-09-26

    The Evaluated Nuclear Structure Data File (ENSDF) is a leading resource for the experimental nuclear data. It is maintained and distributed by the National Nuclear Data Center, Brookhaven National Laboratory. The file is mainly contributed to by an international network of evaluators under the auspice of the International Atomic Energy Agency. The ENSDF is updated, generally by mass number, i.e., evaluating together all isobars for a given mass number. If, however, experimental activity in an isobaric chain is limited to a particular nuclide then only that nuclide is updated. The evaluations are published in the journal Nuclear Data Sheets, Academic Press, a division of Elsevier.

  7. A Structured Debriefing Process for International Business Culture Simulations.

    ERIC Educational Resources Information Center

    McGraw, Peter; Palmer, Ian

    1999-01-01

    Outlines a nine-step structure for debriefing an international business culture simulation. Stresses the need to address three stages in the experiential learning cycle: reflection, processing, and transfer. Appendices include the specific simulation used and a debriefing note. (DB)

  8. Analysis by simulation of the disposition of nuclear fuel waste

    SciTech Connect

    Turek, J.L.

    1980-09-01

    A descriptive simulation model is developed which includes all aspects of nuclear waste disposition. The model is comprised of two systems, the second system orchestrated by GASP IV. A spent fuel generation prediction module is interfaced with the AFR Program Management Information System and a repository scheduling information module. The user is permitted a wide range of options with which to tailor the simulation to any desired storage scenario. The model projects storage requirements through the year 2020. The outputs are evaluations of the impact that alternative decision policies and milestone date changes have on the demand for, the availability of, and the utilization of spent fuel storage capacities. Both graphs and detailed listings are available. These outputs give a comprehensive view of the particular scenario under observation, including the tracking, by year, of each discharge from every reactor. Included within the work is a review of the status of spent fuel disposition based on input data accurate as of August 1980. The results indicate that some temporary storage techniques (e.g., transshipment of fuel and/or additional at-reactor storage pools) must be utilized to prevent reactor shutdowns. These techniques will be required until the 1990's when several AFR facilities, and possibly one repository, can become operational.

  9. Structural performance of HEPA filters under simulated tornado conditions

    NASA Astrophysics Data System (ADS)

    Horak, H. L.; Gregory, W. S.; Ricketts, C. I.; Smith, P. R.

    1982-02-01

    The response of high efficiency particulate air filters to simulated tornado conditions was determined. The data include the structural limits of the filters, their resistance at high flow rates, and the effects of filter design features and tornado parameters. Considering all the filters tested, the mean break pressure or structural limit was found to be 2.35 pse (16.2 kPa). The maximum value was 2.87 psi (19.8 kPa), and the low value found was 1.31 psi (9.0 kPa). The type of failure was usually a medium break of the downstream filter fold. The types of filters that were evaluated were nuclear grade with design flow rates of 1000 cfm (0.472 cu m/s), standard separators, and folded medium design. The parameters evaluated that are characteristic of the filter included manufacturer, separator type, face-guards, pack tightness, and aerosol loading. Manufacturer and medium properties were found to have a large effect on the structural limits.

  10. Report on aging of nuclear power plant reinforced concrete structures

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

    1996-03-01

    The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs.

  11. Integrated Radiation Transport and Nuclear Fuel Performance for Assembly-Level Simulations

    SciTech Connect

    Hamilton, Steven P; Clarno, Kevin T; Philip, Bobby; Berrill, Mark A; Sampath, Rahul S; Allu, Srikanth

    2012-01-01

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step toward incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source-terms, such as neutron flux distribution, coolant conditions and assembly mechanical stresses, of traditional (single-pin) nuclear fuel performance simulation. A novel scheme is introduced for transferring the power distribution from the Scale/Denovo (Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy. With this novel capability, AMPFuel was used to model an entire 1717 pressurized water reactor fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics). A full assembly calculation was executed on Jaguar using 40,000 cores in under 10 hours to model over 160 billion degrees of freedom for 10 loading steps. The single radiation transport calculation required about 50% of the time required to solve the thermo-mechanics with a single loading step, which demonstrates that it is feasible to incorporate, in a single code, a high-fidelity radiation transport capability with a high-fidelity nuclear fuel thermo-mechanics capability and anticipate acceptable computational requirements. The

  12. [Electromagnetic studies of nuclear structure and reactions]. [Nuclear Physics Group, Univ. of New Hampshire

    SciTech Connect

    Not Available

    1992-01-01

    The experimental goals are focused on developing an understanding of strong interactions and the structure of hadronic systems by determination of the electromagnetic response; these goals will be accomplished through coincidence detection of final states. Nuclear modeling objectives are to organize and interpret the data through a consistent description of a broad spectrum of reaction observables; calculations are performed in a nonrelativistic diagrammatic framework as well as a relativistic QHD approach. Work is described according to the following arrangement: direct knockout reactions (completion of [sup 16]O(e,e[prime]p), [sup 12]C(e,e[prime]pp) progress, large acceptance detector physics simulations), giant resonance studies (intermediate-energy experiments with solid-state detectors, the third response function in [sup 12]C(e,e[prime]p[sub 0]) and [sup 16]O(e,e[prime]p[sub 0]), comparison of the [sup 12]C(e, e[prime]p[sub 0]) and [sup 16]O(e,e[prime]p[sub 3]) reactions, quadrupole strength in the [sup 16]O(e,e[prime][alpha][sub 0]) reaction, quadrupole strength in the [sup 12]C(e,e[prime][alpha]) reaction, analysis of the [sup 12]C(e,e[prime]p[sub 1]) and [sup 16]O(e,e[prime]p[sub 3]) angular distributions, analysis of the [sup 40]Ca(e,e[prime]x) reaction at low q, analysis of the higher-q [sup 12]C(e,e[prime]x) data from Bates), models of nuclear structure (experimental work, Hartree-Fock calculations, phonon excitations in spherical nuclei, shell model calculations, variational methods for relativistic fields), and instrumentation development efforts (developments at CEBAF, CLAS contracts, BLAST developments).

  13. New method for calculation of nuclear cluster structure of nuclei

    SciTech Connect

    Ibishi, A.I.

    2005-05-06

    In the calculations of the many-nucleon bound states, using the realistic nucleon-nucleon potential, and a three- and four-nucleon potential, the Exact Many-Body Nuclear Cluster Model (EMBNCM) was found to give accurate results, that converege much more rapidly, than those obtained by the Faddeev equation calculations. With the use of realistic nucleon-nucleon potentials, and many-nucleon potentials, containing strong tensor, Majorana, and repulsive core components, the many-body cluster structure of 16O, 27Al, 44Ti, and 48Ti is discussed. In 27Al(p,x)Na reactions we assume that two different nuclear cluster structures of 27Al, gives us two different isotopes of Na: 22Na and 24Na. But the most important result is the existence of two different permutations symmetries of 27Al. Using new method for calculation of nuclear cluster structure of 27Al, we have found two different nuclear cluster structures of 27Al: 24Na+3He and 25Na+d. The internal nuclear cluster wave functions of different nuclear cluster models (nuclear cluster isomers) of the same isotope are not equivalent, if we take into account Many-Body Nuclear Forces, such as 3BF and 4BF. The core clusters of 16O, 27Al, 44Ti, and 48Ti nuclei have a trigonal-pyramide Td, D2d, and C3v symmetry, while exterior clusters in 16O and 27Al[(24Na +3 He)model] nuclei have a trigonal symmetry C2v, and D3h. We have developed a new system of Jacobi coordinates for our EMBNCM model with the symmetry above. The new computer code for determination of direct nuclear cluster reactions has been written in Mathematica 5 programming language. We have found a high level of dependence of the nuclear cluster wave functions from the center of mass and cluster effects.

  14. Nuclear structure far off stability --Implications for nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Grawe, H.; Blazhev, A.; Górska, M.; Grzywacz, R.; Mach, H.; Mukha, I.

    2006-03-01

    The single-particle structure and shell gap of 100Sn as inferred from previous in-beam γ-ray spectroscopy has been confirmed in recent studies of seniority and spin-gap isomers by γγ, βγ, βpγ, pγ and 2pγ spectroscopy. The results for 94, 95Ag, 98Cd and its N = 50 isotones 96Pd and 94Ru stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np-nh excitations, seniority mixing and E2 polarisation of the 100Sn core. The strong monopole interaction of the Δl = 0, 1 spin/isospin-flip partners πg 9/2- νg 7/2 along the N = 50 isotones and the πf 5/2- νg 9/2 pair of nucleons along the Z = 28 Ni isotopes are decisive for the evolution of the shell structure towards 100Sn and 78Ni. It can be traced back to the tensor force in the effective nucleon-nucleon interaction and provides a straightforward explanation for new shells in neutron-rich light nuclei, implying qualitative predictions for new N = 32, 34 subshells in Ca isotopes, persistence of the 78Ni proton and neutron shell gaps and non-equivalence of the g 9/2 valence mirror Ni isotopes and N = 50 isotones. This is corroborated by recent experimental data on 56, 58Cr and 70-76Ni. The implication of monopole driven shell evolution for apparent spin-orbit splitting towards N ≫ Z and structure along the astrophysical r-path between N = 50 and N = 82 is discussed.

  15. Nuclear microscopy of sperm cell elemental structure

    NASA Astrophysics Data System (ADS)

    Bench, Graham S.; Balhorn, Rod; Friz, Alexander M.

    1995-05-01

    Theories suggest there is a link between protamine concentrations in individual sperm and male fertility. Previously, biochemical analyses have used pooled samples containing millions of sperm to determine protamine concentrations. These methods have not been able to determine what percentage of morphologically normal sperm are biochemically defective and potentially infertile. Nuclear microscopy has been utilized to measure elemental profiles at the single sperm level. By measuring the amount of phosphorus and sulfur, the total DNA and protamine content in individual sperm from fertile bull and mouse semen have been determined. These values agree with results obtained from other biochemical analyses. Nuclear microscopy shows promise for measuring elemental profiles in the chromatin of individual sperm. The technique may be able to resolve theories regarding the importance of protamines to male fertility and identify biochemical defects responsible for certain types of male infertility.

  16. Nuclear microscopy of sperm cell elemental structure

    SciTech Connect

    Bench, G.S.; Balhorn, R.; Friz, A.M.; Freeman, S.P.H.T.

    1994-09-28

    Theories suggest there is a link between protamine concentrations in individual sperm and male fertility. Previously, biochemical analyses have used pooled samples containing millions of sperm to determine protamine concentrations. These methods have not been able to determine what percentage of morphologically normal sperm are biochemically defective and potentially infertile. Nuclear microscopy has been utilized to measure elemental profiles at the single sperm level. By measuring the amount of phosphorus and sulfur, the total DNA and protamine content in individual sperm from fertile bull and mouse semen have been determined. These values agree with results obtained from other biochemical analyses. Nuclear microscopy shows promise for measuring elemental profiles in the chromatin of individual sperm. The technique may be able to resolve theories regarding the importance of protamines to male fertility and identify biochemical defects responsible for certain types of male infertility.

  17. Investigations of nuclear structure and nuclear reactions induced by complex projectiles

    SciTech Connect

    Sarantites, D.G.

    1991-01-01

    The research program of our group touches five areas of nuclear physics: (1) Nuclear structure studies at high spin; (2) Studies at the interface between structure and reactions; (3) Production and study of hot nuclei; (4) Incomplete fusion and fragmentation reactions; and (5) Development and use of novel techniques and instrumentation in the above areas of research. The papers from these areas are discussed in this report.

  18. PREFACE: Structure of Exotic Nuclei and Nuclear Forces

    NASA Astrophysics Data System (ADS)

    Honma, Michio; Otsuka, Takaharu; Aoi, Nori

    2006-11-01

    The International Symposium on `Structure of Exotic Nuclei and Nuclear Forces' was held at The Koshiba Hall, University of Tokyo, on 9 - 12 March 2006. This symposium was organized as an activity of the Grant-in-Aid for the specially promoted area `Monte Carlo Shell Model' from the Ministry of Education, Science, Sports and Culture (MEXT) of Japan. The symposium was sponsored by the Center for Nuclear Study (CNS) and by RIKEN. The purpose of the symposium was to discuss theoretical and experimental developments in the study of the structure of exotic nuclei and its relationship with nuclear forces. There has been much progress recently in our understanding of what the structure of exotic nuclei is and how it can be linked to nuclear forces, with emerging intriguing perspectives. The following subjects were covered in this symposium

  19. Present status and future of the shell model
  20. Effective interaction theories
  21. Experimental results and perspectives
  22. Few-body methods including ab initio calculations
  23. Advancements of mean-fieeld models
  24. Transition between shell and cluster structure>
  25. Nuclear astrophysics and nuclear structure>
  26. Particle physics and the shell model
  27. Emphasis was placed on the interplay between many-body structures and nuclear forces, and on the experimental clarification of these topics. Around 80 participants attended the symposium and we enjoyed 34 excellent and lively invited talks and 26 oral presentations. The organizing committee consisted of B A Brown (MSU), S Fujii (CNS), M Honma (Aizu), T Kajino (NAO), T Mizusaki (Senshu), T Motobayashi (RIKEN), K Muto (TIT), T Otsuka (Chair, Tokyo/CNS/RIKEN), P Ring (TMU), N Shimizu (Scientific Secretary, Tokyo), S Shimoura (CNS), Y Utsuno (Scientific Secretary, JAEA). Finally, we would like to thank all the speakers and the participants as well as the other organizers for their contributions which made the symposium so successful.

  28. Macroscopic nuclear spin diffusion constants of rotating polycrystalline solids from first-principles simulation

    NASA Astrophysics Data System (ADS)

    Halse, Meghan E.; Zagdoun, Alexandre; Dumez, Jean-Nicolas; Emsley, Lyndon

    2015-05-01

    A method for quantitatively calculating nuclear spin diffusion constants directly from crystal structures is introduced. This approach uses the first-principles low-order correlations in Liouville space (LCL) method to simulate spin diffusion in a box, starting from atomic geometry and including both magic-angle spinning (MAS) and powder averaging. The LCL simulations are fit to the 3D diffusion equation to extract quantitative nuclear spin diffusion constants. We demonstrate this method for the case of 1H spin diffusion in ice and L-histidine, obtaining diffusion constants that are consistent with literature values for 1H spin diffusion in polymers and that follow the expected trends with respect to magic-angle spinning rate and the density of nuclear spins. In addition, we show that this method can be used to model 13C spin diffusion in diamond and therefore has the potential to provide insight into applications such as the transport of polarization in non-protonated systems.

  29. High-Fidelity Space-Time Adaptive Multiphysics Simulations in Nuclear Engineering

    SciTech Connect

    Solin, Pavel; Ragusa, Jean

    2014-03-09

    We delivered a series of fundamentally new computational technologies that have the potential to significantly advance the state-of-the-art of computer simulations of transient multiphysics nuclear reactor processes. These methods were implemented in the form of a C++ library, and applied to a number of multiphysics coupled problems relevant to nuclear reactor simulations.

  1. Nuclear Engine System Simulation (NESS). Volume 1: Program user's guide

    NASA Astrophysics Data System (ADS)

    Pelaccio, Dennis G.; Scheil, Christine M.; Petrosky, Lyman J.

    1993-03-01

    A Nuclear Thermal Propulsion (NTP) engine system design analysis tool is required to support current and future Space Exploration Initiative (SEI) propulsion and vehicle design studies. Currently available NTP engine design models are those developed during the NERVA program in the 1960's and early 1970's and are highly unique to that design or are modifications of current liquid propulsion system design models. To date, NTP engine-based liquid design models lack integrated design of key NTP engine design features in the areas of reactor, shielding, multi-propellant capability, and multi-redundant pump feed fuel systems. Additionally, since the SEI effort is in the initial development stage, a robust, verified NTP analysis design tool could be of great use to the community. This effort developed an NTP engine system design analysis program (tool), known as the Nuclear Engine System Simulation (NESS) program, to support ongoing and future engine system and stage design study efforts. In this effort, Science Applications International Corporation's (SAIC) NTP version of the Expanded Liquid Engine Simulation (ELES) program was modified extensively to include Westinghouse Electric Corporation's near-term solid-core reactor design model. The ELES program has extensive capability to conduct preliminary system design analysis of liquid rocket systems and vehicles. The program is modular in nature and is versatile in terms of modeling state-of-the-art component and system options as discussed. The Westinghouse reactor design model, which was integrated in the NESS program, is based on the near-term solid-core ENABLER NTP reactor design concept. This program is now capable of accurately modeling (characterizing) a complete near-term solid-core NTP engine system in great detail, for a number of design options, in an efficient manner. The following discussion summarizes the overall analysis methodology, key assumptions, and capabilities associated with the NESS presents an

  2. Nuclear Engine System Simulation (NESS). Volume 1: Program user's guide

    NASA Technical Reports Server (NTRS)

    Pelaccio, Dennis G.; Scheil, Christine M.; Petrosky, Lyman J.

    1993-01-01

    A Nuclear Thermal Propulsion (NTP) engine system design analysis tool is required to support current and future Space Exploration Initiative (SEI) propulsion and vehicle design studies. Currently available NTP engine design models are those developed during the NERVA program in the 1960's and early 1970's and are highly unique to that design or are modifications of current liquid propulsion system design models. To date, NTP engine-based liquid design models lack integrated design of key NTP engine design features in the areas of reactor, shielding, multi-propellant capability, and multi-redundant pump feed fuel systems. Additionally, since the SEI effort is in the initial development stage, a robust, verified NTP analysis design tool could be of great use to the community. This effort developed an NTP engine system design analysis program (tool), known as the Nuclear Engine System Simulation (NESS) program, to support ongoing and future engine system and stage design study efforts. In this effort, Science Applications International Corporation's (SAIC) NTP version of the Expanded Liquid Engine Simulation (ELES) program was modified extensively to include Westinghouse Electric Corporation's near-term solid-core reactor design model. The ELES program has extensive capability to conduct preliminary system design analysis of liquid rocket systems and vehicles. The program is modular in nature and is versatile in terms of modeling state-of-the-art component and system options as discussed. The Westinghouse reactor design model, which was integrated in the NESS program, is based on the near-term solid-core ENABLER NTP reactor design concept. This program is now capable of accurately modeling (characterizing) a complete near-term solid-core NTP engine system in great detail, for a number of design options, in an efficient manner. The following discussion summarizes the overall analysis methodology, key assumptions, and capabilities associated with the NESS presents an

  3. Nuclear war group survival: Structures and camp site

    SciTech Connect

    David, C.V.

    1987-06-09

    A nuclear war group survival camp is described including a combination of structures, facilities, equipment and other camp site improvements and further comprising: means for protecting people inside structures located above ground against the effects of blast caused by the explosion of a nuclear weapon, on and above ground, within a distance that would create a lethal environment inside any conventionally constructed building structure at such distance; means for removing fallout debris (dust) generated by the explosion in a manner such that the total radiation dosage received by any and all so sheltered people remains below the radiation dose level considered critical.

  4. Generalized Nuclear Data: A New Structure (with Supporting Infrastructure) for Handling Nuclear Data

    NASA Astrophysics Data System (ADS)

    Mattoon, C. M.; Beck, B. R.; Patel, N. R.; Summers, N. C.; Hedstrom, G. W.; Brown, D. A.

    2012-12-01

    The Evaluated Nuclear Data File (ENDF) format was designed in the 1960s to accommodate neutron reaction data to support nuclear engineering applications in power, national security and criticality safety. Over the years, the scope of the format has been extended to handle many other kinds of data including charged particle, decay, atomic, photo-nuclear and thermal neutron scattering. Although ENDF has wide acceptance and support for many data types, its limited support for correlated particle emission, limited numeric precision, and general lack of extensibility mean that the nuclear data community cannot take advantage of many emerging opportunities. More generally, the ENDF format provides an unfriendly environment that makes it difficult for new data evaluators and users to create and access nuclear data. The Cross Section Evaluation Working Group (CSEWG) has begun the design of a new Generalized Nuclear Data (or 'GND') structure, meant to replace older formats with a hierarchy that mirrors the underlying physics, and is aligned with modern coding and database practices. In support of this new structure, Lawrence Livermore National Laboratory (LLNL) has updated its nuclear data/reactions management package Fudge to handle GND structured nuclear data. Fudge provides tools for converting both the latest ENDF format (ENDF-6) and the LLNL Evaluated Nuclear Data Library (ENDL) format to and from GND, as well as for visualizing, modifying and processing (i.e., converting evaluated nuclear data into a form more suitable to transport codes) GND structured nuclear data. GND defines the structure needed for storing nuclear data evaluations and the type of data that needs to be stored. But unlike ENDF and ENDL, GND does not define how the data are to be stored in a file. Currently, Fudge writes the structured GND data to a file using the eXtensible Markup Language (XML), as it is ASCII based and can be viewed with any text editor. XML is a meta-language, meaning that it

  5. Generalized Nuclear Data: A New Structure (with Supporting Infrastructure) for Handling Nuclear Data

    SciTech Connect

    Mattoon, C.M.; Beck, B.R.; Patel, N.R.; Summers, N.C.; Hedstrom, G.W.; Brown, D.A.

    2012-12-15

    The Evaluated Nuclear Data File (ENDF) format was designed in the 1960s to accommodate neutron reaction data to support nuclear engineering applications in power, national security and criticality safety. Over the years, the scope of the format has been extended to handle many other kinds of data including charged particle, decay, atomic, photo-nuclear and thermal neutron scattering. Although ENDF has wide acceptance and support for many data types, its limited support for correlated particle emission, limited numeric precision, and general lack of extensibility mean that the nuclear data community cannot take advantage of many emerging opportunities. More generally, the ENDF format provides an unfriendly environment that makes it difficult for new data evaluators and users to create and access nuclear data. The Cross Section Evaluation Working Group (CSEWG) has begun the design of a new Generalized Nuclear Data (or 'GND') structure, meant to replace older formats with a hierarchy that mirrors the underlying physics, and is aligned with modern coding and database practices. In support of this new structure, Lawrence Livermore National Laboratory (LLNL) has updated its nuclear data/reactions management package Fudge to handle GND structured nuclear data. Fudge provides tools for converting both the latest ENDF format (ENDF-6) and the LLNL Evaluated Nuclear Data Library (ENDL) format to and from GND, as well as for visualizing, modifying and processing (i.e., converting evaluated nuclear data into a form more suitable to transport codes) GND structured nuclear data. GND defines the structure needed for storing nuclear data evaluations and the type of data that needs to be stored. But unlike ENDF and ENDL, GND does not define how the data are to be stored in a file. Currently, Fudge writes the structured GND data to a file using the eXtensible Markup Language (XML), as it is ASCII based and can be viewed with any text editor. XML is a meta-language, meaning that it

  6. Dynamic testing of nuclear power plant structures: an evaluation

    SciTech Connect

    Weaver, H.J.

    1980-02-01

    Lawrence Livermore Laboratory (LLL) evaluated the applications of system identification techniques to the dynamic testing of nuclear power plant structures and subsystems. These experimental techniques involve exciting a structure and measuring, digitizing, and processing the time-history motions that result. The data can be compared to parameters calculated using finite element or other models of the test systems to validate the model and to verify the seismic analysis. This report summarizes work in three main areas: (1) analytical qualification of a set of computer programs developed at LLL to extract model parameters from the time histories; (2) examination of the feasibility of safely exciting nuclear power plant structures and accurately recording the resulting time-history motions; (3) study of how the model parameters that are extracted from the data be used best to evaluate structural integrity and analyze nuclear power plants.

  7. Aqueous Solutions on Silica Surfaces: Structure and Dynamics from Simulations

    NASA Astrophysics Data System (ADS)

    Striolo, Alberto; Argyris, Dimitrios; Tummala, Naga Rajesh

    2009-03-01

    Our group is interested in understanding the properties of aqueous electrolyte solutions at interfaces. The fundamental questions we seek to answer include: (A) how does a solid structure perturb interfacial water? (B) How far from the solid does this perturbation persist? (C) What is the rate of water reorientation and exchange in the perturbed layer? (D) What happens in the presence of simple electrolytes? To address such topics we implemented atomistic molecular dynamics simulations. Recent results for water and simple electrolytes near silicon dioxide surfaces of various degrees of hydroxylation will be presented. The data suggest the formation of a layered aqueous structure near the interface. The density profile of interfacial water seems to dictate the density profiles of aqueous solutions containing NaCl, CaCl2, CsCl, and SrCl2 near the solid surfaces. These results suggest that ion-ion and ion-water correlations are extremely important factors that should be considered when it is desired to predict the distribution of electrolytes near a charged surface. Our results will benefit a number of practical applications including water desalination, exploitation of the oil shale in the Green River Basin, nuclear waste sites remediation, and design of nanofluidic devices.

  8. Information flow and protein dynamics: the interplay between nuclear magnetic resonance spectroscopy and molecular dynamics simulations.

    PubMed

    Pastor, Nina; Amero, Carlos

    2015-01-01

    Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics, and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells. PMID:25999971

  9. Information flow and protein dynamics: the interplay between nuclear magnetic resonance spectroscopy and molecular dynamics simulations

    PubMed Central

    Pastor, Nina; Amero, Carlos

    2015-01-01

    Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics, and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells. PMID:25999971

  10. A phased approach to enable hybrid simulation of complex structures

    NASA Astrophysics Data System (ADS)

    Spencer, Billie F.; Chang, Chia-Ming; Frankie, Thomas M.; Kuchma, Daniel A.; Silva, Pedro F.; Abdelnaby, Adel E.

    2014-08-01

    Hybrid simulation has been shown to be a cost-effective approach for assessing the seismic performance of structures. In hybrid simulation, critical parts of a structure are physically tested, while the remaining portions of the system are concurrently simulated computationally, typically using a finite element model. This combination is realized through a numerical time-integration scheme, which allows for investigation of full system-level responses of a structure in a cost-effective manner. However, conducting hybrid simulation of complex structures within large-scale testing facilities presents significant challenges. For example, the chosen modeling scheme may create numerical inaccuracies or even result in unstable simulations; the displacement and force capacity of the experimental system can be exceeded; and a hybrid test may be terminated due to poor communication between modules (e.g., loading controllers, data acquisition systems, simulation coordinator). These problems can cause the simulation to stop suddenly, and in some cases can even result in damage to the experimental specimens; the end result can be failure of the entire experiment. This study proposes a phased approach to hybrid simulation that can validate all of the hybrid simulation components and ensure the integrity large-scale hybrid simulation. In this approach, a series of hybrid simulations employing numerical components and small-scale experimental components are examined to establish this preparedness for the large-scale experiment. This validation program is incorporated into an existing, mature hybrid simulation framework, which is currently utilized in the Multi-Axial Full-Scale Sub-Structuring Testing and Simulation (MUST-SIM) facility of the George E. Brown Network for Earthquake Engineering Simulation (NEES) equipment site at the University of Illinois at Urbana-Champaign. A hybrid simulation of a four-span curved bridge is presented as an example, in which three piers are

  11. Structural Basis of Vesicle Formation at the Inner Nuclear Membrane

    PubMed Central

    Hagen, Christoph; Dent, Kyle C.; Zeev-Ben-Mordehai, Tzviya; Grange, Michael; Bosse, Jens B.; Whittle, Cathy; Klupp, Barbara G.; Siebert, C. Alistair; Vasishtan, Daven; Bäuerlein, Felix J.B.; Cheleski, Juliana; Werner, Stephan; Guttmann, Peter; Rehbein, Stefan; Henzler, Katja; Demmerle, Justin; Adler, Barbara; Koszinowski, Ulrich; Schermelleh, Lothar; Schneider, Gerd; Enquist, Lynn W.; Plitzko, Jürgen M.; Mettenleiter, Thomas C.; Grünewald, Kay

    2015-01-01

    Summary Vesicular nucleo-cytoplasmic transport is becoming recognized as a general cellular mechanism for translocation of large cargoes across the nuclear envelope. Cargo is recruited, enveloped at the inner nuclear membrane (INM), and delivered by membrane fusion at the outer nuclear membrane. To understand the structural underpinning for this trafficking, we investigated nuclear egress of progeny herpesvirus capsids where capsid envelopment is mediated by two viral proteins, forming the nuclear egress complex (NEC). Using a multi-modal imaging approach, we visualized the NEC in situ forming coated vesicles of defined size. Cellular electron cryo-tomography revealed a protein layer showing two distinct hexagonal lattices at its membrane-proximal and membrane-distant faces, respectively. NEC coat architecture was determined by combining this information with integrative modeling using small-angle X-ray scattering data. The molecular arrangement of the NEC establishes the basic mechanism for budding and scission of tailored vesicles at the INM. PMID:26687357

  12. Separation of technetium from nuclear waste stream simulants. Final report

    SciTech Connect

    Strauss, S.H.

    1995-09-11

    The author studied liquid anion exchangers, such as Aliquat-336 nitrate, various pyridinium nitrates, and related salts, so that they may be applied toward a specific process for extracting (partitioning) and recovering {sup 99}TcO{sub 4}{sup {minus}} from nuclear waste streams. Many of the waste streams are caustic and contain a variety of other ions. For this reason, the author studied waste stream simulants that are caustic and contain appropriate concentrations of selected, relevant ions. Methods of measuring the performance of the exchangers and extractant systems included contact experiments. Batch contact experiments were used to determine the forward and reverse extraction parameters as a function of temperature, contact time, phase ratio, concentration, solvent (diluent), and other physical properties. They were also used for stability and competition studies. Specifically, the author investigated the solvent extraction behavior of salts of perrhenate (ReO{sub 4}{sup {minus}}), a stable (non-radioactive) chemical surrogate for {sup 99}TcO{sub 4}{sup {minus}}. Results are discussed for alternate organic solvents; metalloporphyrins, ferrocenes, and N-cetyl pyridium nitrate as alternate extractant salts; electroactive polymers; and recovery of ReO{sub 4}{sup {minus}} and TcO{sub 4}{sup {minus}}.

  13. Simulating feedback from nuclear clusters: the impact of multiple sources

    NASA Astrophysics Data System (ADS)

    Bourne, Martin A.; Power, Chris

    2016-02-01

    Nuclear star clusters (NCs) are found to exist in the centres of many galaxies and appear to follow scaling relations similar to those of supermassive black holes. Previous analytical work has suggested that such relations are a consequence of feedback-regulated growth. We explore this idea using high-resolution hydrodynamical simulations, focusing on the validity of the simplifying assumptions made in analytical models. In particular, we investigate feedback emanating from multiple stellar sources rather than from a single source, as is usually assumed, and show that collisions between shells of gas swept up by feedback leads to momentum cancellation and the formation of high-density clumps and filaments. This high-density material is resistant both to expulsion from the galaxy potential and to disruption by feedback; if it falls back on to the NC, we expect the gas to be available for further star formation or for feeding a central black hole. We also note that our results may have implications for the evolution of globular clusters and stellar clusters in high-redshift dark matter haloes.

  14. Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Upgrade Activities

    NASA Technical Reports Server (NTRS)

    Emrich, William J., Jr.

    2014-01-01

    Over the past year the Nuclear Thermal Rocket Element Environmental Simulator (NTREES) has been undergoing a significant upgrade beyond its initial configuration. The NTREES facility is designed to perform realistic non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and fuel materials. Although the NTREES facility cannot mimic the neutron and gamma environment of an operating NTR, it can simulate the thermal hydraulic environment within an NTR fuel element to provide critical information on material performance and compatibility. The first phase of the upgrade activities which was completed in 2012 in part consisted of an extensive modification to the hydrogen system to permit computer controlled operations outside the building through the use of pneumatically operated variable position valves. This setup also allows the hydrogen flow rate to be increased to over 200 g/sec and reduced the operation complexity of the system. The second stage of modifications to NTREES which has just been completed expands the capabilities of the facility significantly. In particular, the previous 50 kW induction power supply has been replaced with a 1.2 MW unit which should allow more prototypical fuel element temperatures to be reached. The water cooling system was also upgraded to so as to be capable of removing 100% of the heat generated during. This new setup required that the NTREES vessel be raised onto a platform along with most of its associated gas and vent lines. In this arrangement, the induction heater and water systems are now located underneath the platform. In this new configuration, the 1.2 MW NTREES induction heater will be capable of testing fuel elements and fuel materials in flowing hydrogen at pressures up to 1000 psi at temperatures up to and beyond 3000 K and at near-prototypic reactor channel power densities. NTREES is also capable of testing potential fuel elements with a variety of propellants, including hydrogen with additives to inhibit

  15. Structure of matter, radioactivity, and nuclear fission. Volume 3

    SciTech Connect

    Not Available

    1986-01-01

    Subject matter includes structure of matter (what is matter, forces holding atoms together, visualizing the atom, the chemical elements, atomic symbols, isotopes, radiation from the atom), radioactivity (what holds the nucleus together, can one element change into another element, radiation from the nucleus, half-life, chart of the nuclides), and nuclear fission (nuclear energy release, the fission process, where does fission energy go, radiation and radioactivity resulting from fission).

  16. Nuclear structure from radioactive decay. Annual progress report

    SciTech Connect

    Wood, J.L.

    1991-09-30

    This report discusses nuclear structure from radioactive decay of the following: Neutron-Deficient Iridium Isotopes; Neutron-Deficient Platinum Isotopes; Neutron-Deficient Gold Isotopes; Neutron-Deficient Mercury Isotopes; Neutron-Deficient Thallium Isotopes; Neutron-Deficient Lead Isotopes; Neutron-Deficient Samarium Isotopes; Neutron-Deficient Promethium Isotopes; Neutron-Deficient Neodymium Isotopes; and Neutron-Deficient Praseodymium Isotopes. Also discussed are Nuclear Systematics and Models.

  17. Nuclear microscopy of sperm cell elemental structure

    SciTech Connect

    Bench, G.S.

    1994-12-31

    Theories have suggested that there is a link between protamine concentrations in individual sperm and sperm fertility. At present, biochemical analyses have only been performed on bulk populations and existing methods have not been able to determine what percentage of morphologically normal sperm are biochemically defective and potentially infertile. As part of an investigation into male sperm fertility, nuclear microscopy has been utilized to measure elemental profiles at the single sperm level. By measuring the ratio of Phosphorus to Sulfur the authors have been able to determine the amount of protamine 1 and protamine 2 in individual cells from bulk fertile samples of bull and mouse sperm. Preliminary results show that, for each species, the relative amounts of protamine 1 and protamine 2 in morphologically normal sperm agree well with expected values.

  18. Structural Ceramic Composites for Nuclear Applications

    SciTech Connect

    William Windes; P.A. Lessing; Y. Katoh; L. L. Snead; E. Lara-Curzio; J. Klett; C. Henager, Jr.; R. J. Shinavski

    2005-08-01

    A research program has been established to investigate fiber reinforced ceramic composites to be used as control rod components within a Very High Temperature Reactor. Two candidate systems have been identified, carbon fiber reinforced carbon (Cf/C) and silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites. Initial irradiation stability studies to determine the maximum dose for each composite type have been initiated within the High Flux Isotope Reactor at Oak Ridge National Laboratory. Test samples exposed to 10 dpa irradiation dose have been completed with future samples to dose levels of 20 and 30 dpa scheduled for completion in following years. Mechanical and environmental testing is being conducted concurrently at the Idaho National Laboratory and at Pacific Northwest National Laboratory. High temperature test equipment, testing methodologies, and test samples for high temperature (up to 1600º C) tensile strength and long duration creep studies have been established. Specific attention was paid to the architectural fiber preform design as well as the materials used in construction of the composites. Actual testing of both tubular and flat, "dog-bone" shaped tensile composite specimens will begin next year. Since there is no precedence for using ceramic composites within a nuclear reactor, ASTM standard test procedures will be established from these mechanical and environmental tests. Close collaborations between the U.S. national laboratories and international collaborators (i.e. France and Japan) are being forged to establish both national and international test standards to be used to qualify ceramic composites for nuclear reactor applications.

  19. Structural Composites Corrosive Management by Computational Simulation

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Minnetyan, Levon

    2006-01-01

    A simulation of corrosive management on polymer composites durability is presented. The corrosive environment is assumed to manage the polymer composite degradation on a ply-by-ply basis. The degradation is correlated with a measured Ph factor and is represented by voids, temperature, and moisture which vary parabolically for voids and linearly for temperature and moisture through the laminate thickness. The simulation is performed by a computational composite mechanics computer code which includes micro, macro, combined stress failure, and laminate theories. This accounts for starting the simulation from constitutive material properties and up to the laminate scale which exposes the laminate to the corrosive environment. Results obtained for one laminate indicate that the ply-by-ply managed degradation degrades the laminate to the last one or the last several plies. Results also demonstrate that the simulation is applicable to other polymer composite systems as well.

  20. Computer Simulation Methods for Defect Configurations and Nanoscale Structures

    SciTech Connect

    Gao, Fei

    2010-01-01

    This chapter will describe general computer simulation methods, including ab initio calculations, molecular dynamics and kinetic Monte-Carlo method, and their applications to the calculations of defect configurations in various materials (metals, ceramics and oxides) and the simulations of nanoscale structures due to ion-solid interactions. The multiscale theory, modeling, and simulation techniques (both time scale and space scale) will be emphasized, and the comparisons between computer simulation results and exprimental observations will be made.

  1. 3-D simulation of nanopore structure for DNA sequencing.

    PubMed

    Park, Jun-Mo; Pak, Y Eugene; Chun, Honggu; Lee, Jong-Ho

    2012-07-01

    In this paper, we propose a method for simulating nanopore structure by using conventional 3-D simulation tool to mimic the I-V behavior of the nanopore structure. In the simulation, we use lightly doped silicon for ionic solution where some parameters like electron affinity and dielectric constant are fitted to consider the ionic solution. By using this method, we can simulate the I-V behavior of nanopore structure depending on the location and the size of the sphere shaped silicon oxide which is considered to be an indicator of a DNA base. In addition, we simulate an Ionic Field Effect Transistor (IFET) which has basically the nanopore structure, and show that the simulated curves follow sufficiently the I-V behavior of the measurement data. Therefore, we think it is reasonable to apply parameter modeling mentioned above to simulate nanopore structure. The key idea is to modify electron affinity of silicon which is used to mimic the KCl solution to avoid band bending and depletion inside the nanopore. We could efficiently utilize conventional 3-D simulation tool to simulate the I-V behavior of nanopore structures. PMID:22966538

  2. 3D structure and nuclear targets

    NASA Astrophysics Data System (ADS)

    Dupré, Raphaël; Scopetta, Sergio

    2016-06-01

    Recent experimental and theoretical ideas are laying the ground for a new era in the knowledge of the parton structure of nuclei. We report on two promising directions beyond inclusive deep inelastic scattering experiments, aimed at, among other goals, unveiling the three-dimensional structure of the bound nucleon. The 3D structure in coordinate space can be accessed through deep exclusive processes, whose non-perturbative content is parametrized in terms of generalized parton distributions. In this way the distribution of partons in the transverse plane will be obtained, providing a pictorial view of the realization of the European Muon Collaboration effect. In particular, we show how, through the generalized parton distribution framework, non-nucleonic degrees of freedom in nuclei can be unveiled. Analogously, the momentum space 3D structure can be accessed by studying transverse-momentum-dependent parton distributions in semi-inclusive deep inelastic scattering processes. The status of measurements is also summarized, in particular novel coincidence measurements at high-luminosity facilities, such as Jefferson Laboratory. Finally the prospects for the next years at future facilities, such as the 12GeV Jefferson Laboratory and the Electron Ion Collider, are presented.

  3. Nuclear spins and moments: Fundamental structural information

    SciTech Connect

    Semmes, P.B.

    1991-12-31

    Predictions for the low energy structure of well deformed odd-A Pm and Sm nuclei in the A {approx} 130 region are given, based on the particle-rotor model. Distinctive magnetic dipole properties (static moments and transition rates) are expected for certain Nilsson configurations, and comparisons to recent data are made for {sup 133}Pm, {sup 135}Sm and {sup 133}Sm.

  4. Nuclear spins and moments: Fundamental structural information

    SciTech Connect

    Semmes, P.B.

    1991-01-01

    Predictions for the low energy structure of well deformed odd-A Pm and Sm nuclei in the A {approx} 130 region are given, based on the particle-rotor model. Distinctive magnetic dipole properties (static moments and transition rates) are expected for certain Nilsson configurations, and comparisons to recent data are made for {sup 133}Pm, {sup 135}Sm and {sup 133}Sm.

  5. Nuclear structure at intermediate energies. Progress report

    SciTech Connect

    Bonner, B.E.; Mutchler, G.S.

    1992-07-15

    We report here oil the progress that we made for the nine months beginning October 1, 1991 for DOE Grant No. DE-FG05-87ER40309. The report covers the third year of a three year grant. Since we are submitting an accompanying Grant Renewal Proposal, we provide in this report more background information than usual for the different projects. The theme that unites the experiments undertaken by the Bonner Lab Medium Energy Group is a determination to understand in detail the many facets and manifestations of the strong interaction, that which is now referred to as nonperturbative QCD. Whether we are investigating the question of just what does carry the spin of baryons, or the extent of the validity of the SU(6) wavefunctions for the excited hyperons (as will be measured in our CEBAF experiment), or questions associated with the formation of a new state of matter predicted by QCD (the subject of AGS {bar p} experiment E854, AGS heavy ion experiment E810, as-well as the approved STAR experiment at RHIC), - all these projects share this common goal. FNAL E683 may well open a new field of investigation in nuclear physics: That of just how colored quarks and gluons interact with nuclear matter as they traverse nuclei of different-sizes. In most all of the experiments mentioned, above, the Bonner Lab Group is playing major leadership roles as well as doing a big fraction of the hard work that such experiments require. We use many of the facilities that are available to the intermediate energy physics community and we use our expertise to design and fabricate the detectors and instrumentation that are required to perform the measurements which we decide to do. The format we follow in the Progress Report is,to provide a concise, but fairly complete write-up on each project. The publications listed in Section In give much greater detail on many of the projects. The aim in this report is to focus on the physics goals, the results, and their significance.

  6. Probing nuclear structure of {sup 124}Xe

    SciTech Connect

    Saha, B.; Dewald, A.; Moeller, O.; Peusquens, R.; Jessen, K.; Fitzler, A.; Klug, T.; Tonev, D.; Brentano, P. von; Jolie, J.; Gall, B.J.P.; Petkov, P.

    2004-09-01

    Excited states in {sup 124}Xe were populated in the fusion-evaporation reaction {sup 110}Pd({sup 18}O,4n){sup 124}Xe at a beam energy of 80 MeV. A recoil distance measurement using the Euroball spectrometer in Strasbourg and the Cologne plunger was performed. Altogether 19 lifetimes of excited states in six different bands were determined using gated spectra only, in order to avoid problems related to feeding. The measured B(E2) values were used to derive the nuclear deformation of {sup 124}Xe and the interaction of the ground state band with two s bands. Two sd-IBM-1 calculations with two Hamiltonians of different complexities were performed, which show a good agreement with the measured B(E2) values in the ground state band and the quasi-{gamma} band. The deduced B(M1) values for the regular M1 band show the behavior expected for magnetic rotation. However, it is also shown that these experimental B(M1) values can be described on the basis of a rotational band as well.

  7. Nuclear structure at high angular momentum

    SciTech Connect

    Stephens, F.S.

    1980-06-01

    This review paper begins by discussing the limits faced in the attempts to get nuclei to hold very high angular momentum. The method presently used to produce nuclei with the maximum angular momentum is described. Then the physics of high-spin states is taken up; some properties of a purely collective, classical rotor are described, and the effects of coupling single-particle motion to this are considered. Next, backbending, its causes, and a new spectroscopy of bands and backbends at high spin values are discussed. Noncollective states occur when the nuclear angular momentum is carried by a few high-j particles and is aligned along a symmetry axis. There results an irregular yrast line, along which there are no collective transitions. Noncollective behavior in the lead region, the hafnium region, and the N = 82 region is examined. Then the discussion moves on to collective behavior and recent studies on continuum spectra. Evidence for rotation is given, and effective moments of inertia for this rotation are evaluated. Finally, current ..gamma..-ray energy correlation studies are described. 68 references, 36 figures. (RWR)

  8. The Structure Inventory of the Nuclear Pore Complex.

    PubMed

    Schwartz, Thomas U

    2016-05-22

    The nuclear pore complex (NPC) is the principal gateway for molecular exchange between nucleus and cytoplasm across the nuclear envelope. Due to its sheer size of estimated 50-112MDa and its complex buildup from about 500-1000 individual proteins, it is a difficult object to study for structural biologists. Here, I review the extensive ensemble of high-resolution structures of the building blocks of the NPC. Concurrent with the increase in size and complexity, these latest, large structures and assemblies can now be used as the basis for hybrid approaches, primarily in combination with cryo-electron microscopic analysis, generating the first structure-based assembly models of the NPC. Going forward, the structures will be critically important for a detailed analysis of the NPC, including function, evolution, and assembly. PMID:27016207

  9. Thermal Simulator Development: Non-Nuclear Testing of Space Fission Systems

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon M.; Dickens, Ricky E.

    2006-01-01

    Non-nuclear testing can be a valuable tool in the development of a space nuclear power system. At the NASA MSFC Early Flight Fission Test Facility (EFF-TF), highly designed electric heaters are used to simulate the heat from nuclear fuel to test space fission power and propulsion systems. To allow early utilization, nuclear system designs must be relatively simple, easy to fabricate, and easy to test using non-nuclear heaters to closely mimic heat from fission. In this test strategy, highly designed electric heaters are used to simulate the heat from nuclear fuel, allowing one to develop a significant understanding of individual components and integrated system operation without the cost, time and safety concerns associated with nuclear testing.

  10. Nuclear Structure Corrections in Muonic Deuterium

    SciTech Connect

    Pachucki, Krzysztof

    2011-05-13

    The muonic hydrogen experiment measuring the 2P-2S transition energy [R. Pohl et al., Nature (London) 466, 213 (2010)] is significantly discrepant with theoretical predictions based on quantum electrodynamics. A possible approach to resolve this conundrum is to compare experimental values with theoretical predictions in another system, muonic deuterium {mu}D. The only correction which might be questioned in {mu}D is that due to the deuteron polarizability. We investigate this effect in detail and observe cancellation with the elastic contribution. The total value obtained for the deuteron structure correction in the 2P-2S transition is 1.680(16) meV.

  11. Simulation of the Band Structure of Graphene and Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Mina, Aziz N.; Awadallah, Attia A.; Phillips, Adel H.; Ahmed, Riham R.

    2012-02-01

    Simulation technique has been performed to simulate the band structure of both graphene and carbon nanotube. Accordingly, the dispersion relations for graphene and carbon nanotube are deduced analytically, using the tight binding model & LCAO scheme. The results from the simulation of the dispersion relation of both graphene and carbon nanotube were found to be consistent with those in the literature which indicates the correctness of the process of simulation technique. The present research is very important for tailoring graphene and carbon nanotube with specific band structure, in order to satisfy the required electronic properties of them.

  12. High-spin nuclear structure data on the Internet

    SciTech Connect

    Singh, B. |

    1997-12-31

    The study of nuclear structure at fast nuclear rotations, using fusion-evaporation reactions, started in the early sixties but since the experimental observation of superdeformation about a decade ago it has become one of the most pursued research topics in nuclear physics. Large gamma-ray detector arrays GAMMASPHERE, EUROGAM, and GASP were developed during the last few years and these continue to produce a wealth of new, information about the properties of nuclei at high spins, including superdeformation. It is considered vital to compile, evaluate and systematize published data on many thousands of levels and gamma rays and associated nuclear bands obtained in such studies and make these available to the research community in conveniently retrievable and modern formats. This talk will describe the numerical, bibliographic and other high-spin related databases that are already accessible via INTERNET. Present limitations and ways to improve the current status and display of such databases will also be discussed.

  13. Nuclear clusters and structure in light nuclei

    SciTech Connect

    Kokalova, Tz.; Oertzen, W. von; Thummerer, S.; Bohlen, H.G.; Milin, M.; Tumino, A.; De Angelis, G.; Farnea, E.; Axiotis, M.; Marginean, N.; Napoli, D.R.; Lenzi, S.M.; Ur, C.; Rousseau, M.; Papka, P.

    2004-02-27

    We have studied the {gamma}-decay properties of 21Ne up to the limits of the particle emission thresholds in order to establish the band structure. The GASP {gamma}-ray detector array together with the multi-detector array, ISIS, were used for the selection of the reaction channels. The reaction 16O(7Li,pn)21Ne has been studied at E=29 MeV. The observed decays in 21Ne, support the identification of parity doublets with states of opposite parity connected by strong dipole transitions. The behaviour of the octupole deformed bands in 21Ne is interpreted as consisting of an intrinsic reflection asymmetric (4He+16O)-structure with an additional valence neutron in {sigma}- and {pi}-orbitals. Using the same experimental set-up the emission of the light unbound cluster 8Be has been studied in the reaction 18O+13C{yields}31Si{yields}23Ne+8Be. The emission has been studied relative to the sequential emission of 2{alpha}-particles.

  14. Development of High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    This viewgraph presentation reviews the development of a simulator for non-nuclear tests for the development of a space nuclear power system. The development of the Instrumented Thermal Simulator is to assist in developing an understanding of individual components and integrated system operation without the cost, time, safety concerns associated with nuclear testing. The presentation shows the design, the electrical integration, the hardware, and the assembly of the simulators. There are slides that show the test plan, the analysis, and the initial results.

  15. Live CLEM imaging to analyze nuclear structures at high resolution.

    PubMed

    Haraguchi, Tokuko; Osakada, Hiroko; Koujin, Takako

    2015-01-01

    Fluorescence microscopy (FM) and electron microscopy (EM) are powerful tools for observing molecular components in cells. FM can provide temporal information about cellular proteins and structures in living cells. EM provides nanometer resolution images of cellular structures in fixed cells. We have combined FM and EM to develop a new method of correlative light and electron microscopy (CLEM), called "Live CLEM." In this method, the dynamic behavior of specific molecules of interest is first observed in living cells using fluorescence microscopy (FM) and then cellular structures in the same cell are observed using electron microscopy (EM). Following image acquisition, FM and EM images are compared to enable the fluorescent images to be correlated with the high-resolution images of cellular structures obtained using EM. As this method enables analysis of dynamic events involving specific molecules of interest in the context of specific cellular structures at high resolution, it is useful for the study of nuclear structures including nuclear bodies. Here we describe Live CLEM that can be applied to the study of nuclear structures in mammalian cells. PMID:25555577

  16. Chapter 2: Simulations of the Structure of Cellulose

    SciTech Connect

    Matthews, J. F.; Himmel, M. E.; Brady, J. W.

    2010-01-01

    Cellulose is the homopolymer of (1 {yields} 4)-{beta}-D-glucose. The chemical composition of this polymer is simple, but understanding the conformation and packing of cellulose molecules is challenging. This chapter describes the structure of cellulose from the perspective of molecular mechanics simulations, including conformational analysis of cellobiose and simulations of hydrated cellulose I{beta} with CSFF and GLYCAM06, two sets of force field parameters developed specifically for carbohydrates. Many important features observed in these simulations are sensitive to differences in force field parameters, giving rise to dramatically different structures. The structures and properties of non-naturally occurring cellulose allomorphs (II, III, and IV) are also discussed.

  17. A-dependence of weak nuclear structure functions

    SciTech Connect

    Haider, H.; Athar, M. Sajjad; Simo, I. Ruiz

    2015-05-15

    Effect of nuclear medium on the weak structure functions F{sub 2}{sup A}(x, Q{sup 2}) and F{sub 3}{sup A}(x, Q{sup 2}) have been studied using charged current (anti)neutrino deep inelastic scattering on various nuclear targets. Relativistic nuclear spectral function which incorporate Fermi motion, binding and nucleon correlations are used for the calculations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, F{sub i}{sup A}/F{sub i}{sup proton} and F{sub i}{sup A}/F{sub i}{sup deuteron}(i=2,3, A={sup 12}C, {sup 16}O, CH and H{sub 2}O) are obtained.

  18. Structure and gating of the nuclear pore complex

    PubMed Central

    Eibauer, Matthias; Pellanda, Mauro; Turgay, Yagmur; Dubrovsky, Anna; Wild, Annik; Medalia, Ohad

    2015-01-01

    Nuclear pore complexes (NPCs) perforate the nuclear envelope and allow the exchange of macromolecules between the nucleus and the cytoplasm. To acquire a deeper understanding of this transport mechanism, we analyse the structure of the NPC scaffold and permeability barrier, by reconstructing the Xenopus laevis oocyte NPC from native nuclear envelopes up to 20 Å resolution by cryo-electron tomography in conjunction with subtomogram averaging. In addition to resolving individual protein domains of the NPC constituents, we propose a model for the architecture of the molecular gate at its central channel. Furthermore, we compare and contrast this native NPC structure to one that exhibits reduced transport activity and unveil the spatial properties of the NPC gate. PMID:26112706

  19. 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

  20. 10. Photocopy of drawing, February 1958, NUCLEAR REACTOR FACILITY, STRUCTURAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Photocopy of drawing, February 1958, NUCLEAR REACTOR FACILITY, STRUCTURAL CROSS SECTION. Giffals & Vallet, Inc., L. Rosetti, Associated Architects and Engineers, Detroit, Michigan; and U.S. Army Engineer Division, New England Corps of Engineers, Boston, Massachusetts. Drawing Number 35-84-04. (Original: AMTL Engineering Division, Watertown). - Watertown Arsenal, Building No. 100, Wooley Avenue, Watertown, Middlesex County, MA

  1. Passive cooling system for nuclear reactor containment structure

    DOEpatents

    Gou, Perng-Fei; Wade, Gentry E.

    1989-01-01

    A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

  2. Natural circulating passive cooling system for nuclear reactor containment structure

    DOEpatents

    Gou, Perng-Fei; Wade, Gentry E.

    1990-01-01

    A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

  3. In situ structural analysis of the human nuclear pore complex.

    PubMed

    von Appen, Alexander; Kosinski, Jan; Sparks, Lenore; Ori, Alessandro; DiGuilio, Amanda L; Vollmer, Benjamin; Mackmull, Marie-Therese; Banterle, Niccolo; Parca, Luca; Kastritis, Panagiotis; Buczak, Katarzyna; Mosalaganti, Shyamal; Hagen, Wim; Andres-Pons, Amparo; Lemke, Edward A; Bork, Peer; Antonin, Wolfram; Glavy, Joseph S; Bui, Khanh Huy; Beck, Martin

    2015-10-01

    Nuclear pore complexes are fundamental components of all eukaryotic cells that mediate nucleocytoplasmic exchange. Determining their 110-megadalton structure imposes a formidable challenge and requires in situ structural biology approaches. Of approximately 30 nucleoporins (Nups), 15 are structured and form the Y and inner-ring complexes. These two major scaffolding modules assemble in multiple copies into an eight-fold rotationally symmetric structure that fuses the inner and outer nuclear membranes to form a central channel of ~60 nm in diameter. The scaffold is decorated with transport-channel Nups that often contain phenylalanine-repeat sequences and mediate the interaction with cargo complexes. Although the architectural arrangement of parts of the Y complex has been elucidated, it is unclear how exactly it oligomerizes in situ. Here we combine cryo-electron tomography with mass spectrometry, biochemical analysis, perturbation experiments and structural modelling to generate, to our knowledge, the most comprehensive architectural model of the human nuclear pore complex to date. Our data suggest previously unknown protein interfaces across Y complexes and to inner-ring complex members. We show that the transport-channel Nup358 (also known as Ranbp2) has a previously unanticipated role in Y-complex oligomerization. Our findings blur the established boundaries between scaffold and transport-channel Nups. We conclude that, similar to coated vesicles, several copies of the same structural building block--although compositionally identical--engage in different local sets of interactions and conformations. PMID:26416747

  4. Development of High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, S. M.; Farmer, J.; Dixon, D.; Kapernick, R.; Dickens, R.; Adams, M.

    2007-01-01

    Non-nuclear testing can be a valuable tool in development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Work at the NASA Marshall Space Flight Center seeks to develop high fidelity thermal simulators that not only match the static power profile that would be observed in an operating, fueled nuclear reactor, but to also match the dynamic fuel pin performance during feasible transients. Comparison between the fuel pins and thermal simulators is made at the fuel clad surface, which corresponds to the sheath surface in the thermal simulator. Static and dynamic fuel pin performance was determined using SINDA-FLUINT analysis, and the performance of conceptual thermal simulator designs was compared to the expected nuclear performance. Through a series of iterative analysis, a conceptual high fidelity design will be developed, followed by engineering design, fabrication, and testing to validate the overall design process. Although the resulting thermal simulator will be designed for a specific reactor concept, establishing this rigorous design process will assist in streamlining the thermal simulator development for other reactor concepts.

  5. 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.

  6. Specification and verification of nuclear-power-plant training-simulator response characteristics. Part II. Conclusions and recommendations

    SciTech Connect

    Haas, P M; Selby, D L; Kerlin, T W; Felkins, L

    1982-05-01

    The nuclear industry should adopt and NRC regulatory and research actions should support the systems approach to training as a structured framework for development and validation of personnel training systems. Potential exists for improving the ability to assess simulator fidelity. Systems Identification Technology offers a potential framework for model validation. Installation of the data collection/recording equipment required by NUREG-0696 could provide a vastly improved source of data for simulator fidelity assessment. The NRC needs to continue its post-TMI actions to involve itself more rigorously and more formally in the entire process of NPP personnel training system development. However, this involvement should be a participative one with industry. The existing similator standards and guidelines should be reorganized to support the use of systems approach to training. The standards should require and support a holistic approach to training system development that recognizes simulators and simulator training as only parts of the complete training program and full-scope, high-fidelity, site-specific simulators as only one useful training device. Some recommendations for adapting the SAT/ISD process to the nuclear industry are: The formation of an NRC/industry planning/coordination group, a program planning study to develop a programmatic plan, development of a user's guide and NRC/industry workshops to establish common terminology and practice, and a pilot study applying the adopted SAT/ISD methodology to an actual nuclear industry training program.

  7. Simulation of Sintering of Layered Structures

    SciTech Connect

    OLEVSKY,EUGENE; TIKARE,VEENA; GARINO,TERRY J.; BRAGINSKY,MICHAEL V.

    2000-11-22

    An integrated approach, combining the continuum theory of sintering and Potts model based mesostructure evolution analysis, is used to solve the problem of bi-layered structure sintering. Two types of bi-layered structures are considered: layers of the same material with different initial porosity, and layers of two different materials. The effective sintering stress for the bi-layer powder sintering is derived, both at the meso- and the macroscopic levels. Macroscopic shape distortions and spatial distributions of porosity are determined as functions of the dimensionless specific time of sintering. The effect of the thickness of the layers on shrinkage, warpage, and pore-grain structure is studied. Ceramic ZnO powders are employed as a model experimental system to assess the model predictions.

  8. Design of Accelerator Online Simulator Server Using Structured Data

    SciTech Connect

    Shen, Guobao; Chu, Chungming; Wu, Juhao; Kraimer, Martin; /Argonne

    2012-07-06

    Model based control plays an important role for a modern accelerator during beam commissioning, beam study, and even daily operation. With a realistic model, beam behaviour can be predicted and therefore effectively controlled. The approach used by most current high level application environments is to use a built-in simulation engine and feed a realistic model into that simulation engine. Instead of this traditional monolithic structure, a new approach using a client-server architecture is under development. An on-line simulator server is accessed via network accessible structured data. With this approach, a user can easily access multiple simulation codes. This paper describes the design, implementation, and current status of PVData, which defines the structured data, and PVAccess, which provides network access to the structured data.

  9. Precision Penning Trap Mass Measurements for Nuclear Structure at Triumf

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, A. A.; Dilling, J.; Andreoiu, C.; Brunner, T.; Chaudhuri, A.; Chowdhury, U.; Delheij, P.; Ettenauer, S.; Frekers, D.; Gallant, A. T.; Grossheim, A.; Gwinner, G.; Lennarz, A.; Mané, E.; Pearson, M. R.; Schultz, B. E.; Simon, M. C.; Simon, V. V.

    2013-03-01

    Precision determinations of ground state or even isomeric state masses reveal fingerprints of nuclear structure. In particular at the limits at existence for very neutron-rich or deficient isotopes, this allows one to find detailed information about nuclear structure from separation energies or binding energies. This is important to test theoretical predictions or to refine model approaches, for example for new "magic numbers," as predicted around N = 34, where strong indications exist that the inclusion of NNN forces in theoretical calculations for Ca isotopes leads to significantly better predictions for ground state binding energies. Similarly, halo nuclei present an excellent application for ab-initio theory, where ground state properties, like masses and radii, present prime parameters for testing our understanding of nuclear structure. Precision mass determinations at TRIUMF are carried out with the TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) system. It is an ion trap setup coupled to the on-line facility ISAC. TITAN has measured masses of isotopes as short-lived as 9 ms (almost an order of magnitude shorter-lived than any other Penning trap system) and the only one with charge breeding capabilities, a feature that allows us to boost the precision by almost 2 orders of magnitude. We recently were able to make use of this feature by measuring short-lived Rb-isotopes, up to 74Rb, and reaching the 12+ charge state, which together with other improvements lead to an increase in precision by a factor 36.

  10. Nuclear structure studies with gamma-ray beams

    DOE PAGESBeta

    Tonchev, Anton; Bhatia, Chitra; Kelley, John; Raut, Rajarshi; Rusev, Gencho; Tornow, Werner; Tsoneva, Nadia

    2015-05-28

    In stable and weakly bound neutron-rich nuclei, a resonance-like concentration of dipole states has been observed for excitation energies below the neutron-separation energy. This clustering of strong dipole states has been named the Pygmy Dipole Resonance (PDR) in contrast to the Giant Dipole Resonance (GDR) that dominates the E1 response. Understanding the PDR is presently of great interest in nuclear structure and nuclear astrophysics. High-sensitivity studies of E1 and M1 transitions in closed-shell nuclei using monoenergetic and 100% linearly-polarized photon beams are presented.

  11. Orbital transfer of large space structures with nuclear electric rockets

    NASA Technical Reports Server (NTRS)

    Silva, T. H.; Byers, D. C.

    1980-01-01

    This paper discusses the potential application of electric propulsion for orbit transfer of a large spacecraft structure from low earth orbit to geosynchronous altitude in a deployed configuration. The electric power was provided by the spacecraft nuclear reactor space power system on a shared basis during transfer operations. Factors considered with respect to system effectiveness included nuclear power source sizing, electric propulsion thruster concept, spacecraft deployment constraints, and orbital operations and safety. It is shown that the favorable total impulse capability inherent in electric propulsion provides a potential economic advantage over chemical propulsion orbit transfer vehicles by reducing the number of Space Shuttle flights in ground-to-orbit transportation requirements.

  12. Storage ring mass spectrometry for nuclear structure and astrophysics research

    NASA Astrophysics Data System (ADS)

    Zhang, Y. H.; Litvinov, Yu A.; Uesaka, T.; Xu, H. S.

    2016-07-01

    In the last two and a half decades ion storage rings have proven to be powerful tools for precision experiments with unstable nuclides in the realm of nuclear structure and astrophysics. There are presently three storage ring facilities in the world at which experiments with stored radioactive ions are possible. These are the ESR in GSI, Darmstadt/Germany, the CSRe in IMP, Lanzhou/China, and the R3 storage ring in RIKEN, Saitama/Japan. In this work, an introduction to the facilities is given. Selected characteristic experimental results and their impact in nuclear physics and astrophysics are presented. Planned technical developments and the envisioned future experiments are outlined.

  13. NUCLEAR STRUCTURE AND DECAY DATA: INTRODUCTION TO RELEVANT WEB PAGES.

    SciTech Connect

    BURROWS, T.W.; MCLAUGHLIN, P.D.; NICHOLS, A.L.

    2005-04-04

    A brief description is given of the nuclear data centers around the world able to provide access to those databases and programs of highest relevance to nuclear structure and decay data specialists. A number of Web-page addresses are also provided for the reader to inspect and investigate these data and codes for study, evaluation and calculation. These instructions are not meant to be comprehensive, but should provide the reader with a reasonable means of electronic access to the most important data sets and programs.

  14. Phase structure in a chiral model of nuclear matter

    SciTech Connect

    Phat, Tran Huu; Anh, Nguyen Tuan; Tam, Dinh Thanh

    2011-08-15

    The phase structure of symmetric nuclear matter in the extended Nambu-Jona-Lasinio (ENJL) model is studied by means of the effective potential in the one-loop approximation. It is found that chiral symmetry gets restored at high nuclear density and a typical first-order phase transition of the liquid-gas transition occurs at zero temperature, T=0, which weakens as T grows and eventually ends up with a second-order critical point at T=20 MeV. This phase transition scenario is confirmed by investigating the evolution of the effective potential versus the effective nucleon mass and the equation of state.

  15. Atmospheric icing of structures: Observations and simulations

    NASA Astrophysics Data System (ADS)

    Ágústsson, H.; Elíasson, Á. J.; Thorsteins, E.; Rögnvaldsson, Ó.; Ólafsson, H.

    2012-04-01

    This study compares observed icing in a test span in complex orography at Hallormsstaðaháls (575 m) in East-Iceland with parameterized icing based on an icing model and dynamically downscaled weather at high horizontal resolution. Four icing events have been selected from an extensive dataset of observed atmospheric icing in Iceland. A total of 86 test-spans have been erected since 1972 at 56 locations in complex terrain with more than 1000 icing events documented. The events used here have peak observed ice load between 4 and 36 kg/m. Most of the ice accretion is in-cloud icing but it may partly be mixed with freezing drizzle and wet snow icing. The calculation of atmospheric icing is made in two steps. First the atmospheric data is created by dynamically downscaling the ECMWF-analysis to high resolution using the non-hydrostatic mesoscale Advanced Research WRF-model. The horizontal resolution of 9, 3, 1 and 0.33 km is necessary to allow the atmospheric model to reproduce correctly local weather in the complex terrain of Iceland. Secondly, the Makkonen-model is used to calculate the ice accretion rate on the conductors based on the simulated temperature, wind, cloud and precipitation variables from the atmospheric data. In general, the atmospheric model correctly simulates the atmospheric variables and icing calculations based on the atmospheric variables correctly identify the observed icing events, but underestimate the load due to too slow ice accretion. This is most obvious when the temperature is slightly below 0°C and the observed icing is most intense. The model results improve significantly when additional observations of weather from an upstream weather station are used to nudge the atmospheric model. However, the large variability in the simulated atmospheric variables results in high temporal and spatial variability in the calculated ice accretion. Furthermore, there is high sensitivity of the icing model to the droplet size and the possibility that

  16. Effects of realistic tensor force on nuclear structure

    SciTech Connect

    Nakada, H.

    2012-10-20

    First-order tensor-force effects on nuclear structure are investigated in the self-consistent mean-field and RPA calculations with the M3Y-type semi-realistic interactions, which contain the realistic tensor force. The tensor force plays a key role in Z- or N-dependence of the shell structure, and in transitions involving spin degrees-of-freedom. It is demonstrated that the semi-realistic interactions successfully describe the N-dependence of the shell structure in the proton-magic nuclei (e.g. Ca and Sn), and the magnetic transitions (e.g. M1 transition in {sup 208}Pb).

  17. Dynamics of adaptive structures: Design through simulations

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Alexander, S.

    1993-01-01

    The use of a helical bi-morph actuator/sensor concept by mimicking the change of helical waveform in bacterial flagella is perhaps the first application of bacterial motions (living species) to longitudinal deployment of space structures. However, no dynamical considerations were analyzed to explain the waveform change mechanisms. The objective is to review various deployment concepts from the dynamics point of view and introduce the dynamical considerations from the outset as part of design considerations. Specifically, the impact of the incorporation of the combined static mechanisms and dynamic design considerations on the deployment performance during the reconfiguration stage is studied in terms of improved controllability, maneuvering duration, and joint singularity index. It is shown that intermediate configurations during articulations play an important role for improved joint mechanisms design and overall structural deployability.

  18. Nuclear power: Fourth edition

    SciTech Connect

    Deutsch, R.W.

    1986-01-01

    This book describes the basics of nuclear power generation, explaining both the benefits and the real and imagined risks of nuclear power. It includes a discussion of the Three Mile Island accident and its effects. Nuclear Power has been used in the public information programs of more than 100 utilities. The contents discussed are: Nuclear Power and People; Why Nuclear Power. Electricity produced by coal; Electricity produced by nuclear fuel; Nuclear plant sites in the United States; Short History of Commercial Nuclear Power; U.S. nuclear submarines, Regulation of Nuclear Power Plants; Licensing process, Nuclear Power Plant Operator Training; Nuclear power plant simulator, Are Nuclear Plants Safe.; Containment structure, Nuclear Power Plant Insurance; Is Radiation Dangerous.; Man-made radiation, What is Nuclear Fuel.; Fuel cycle for commercial nuclear power plants; Warm Water Discharge; Cooling tower; Protection of Radioactive Materials; Plutonium and Proliferation; Disposal of Radioactive Wastes; Are Alternate Energy Sources Available.; Nuclear Opposition; and Nuclear Power in the Future.

  19. Numerical simulation of tornado wind loading on structures

    NASA Technical Reports Server (NTRS)

    Maiden, D. E.

    1976-01-01

    A numerical simulation of a tornado interacting with a building was undertaken in order to compare the pressures due to a rotational unsteady wind with that due to steady straight winds used in design of nuclear facilities. The numerical simulations were performed on a two-dimensional compressible hydrodynamics code. Calculated pressure profiles for a typical building were then subjected to a tornado wind field and the results were compared with current quasisteady design calculations. The analysis indicates that current design practices are conservative.

  20. Estimating Building Simulation Parameters via Bayesian Structure Learning

    SciTech Connect

    Edwards, Richard E; New, Joshua Ryan; Parker, Lynne Edwards

    2013-01-01

    Many key building design policies are made using sophisticated computer simulations such as EnergyPlus (E+), the DOE flagship whole-building energy simulation engine. E+ and other sophisticated computer simulations have several major problems. The two main issues are 1) gaps between the simulation model and the actual structure, and 2) limitations of the modeling engine's capabilities. Currently, these problems are addressed by having an engineer manually calibrate simulation parameters to real world data or using algorithmic optimization methods to adjust the building parameters. However, some simulations engines, like E+, are computationally expensive, which makes repeatedly evaluating the simulation engine costly. This work explores addressing this issue by automatically discovering the simulation's internal input and output dependencies from 20 Gigabytes of E+ simulation data, future extensions will use 200 Terabytes of E+ simulation data. The model is validated by inferring building parameters for E+ simulations with ground truth building parameters. Our results indicate that the model accurately represents parameter means with some deviation from the means, but does not support inferring parameter values that exist on the distribution's tail.

  1. Lattice Boltzmann Model for Electronic Structure Simulations

    NASA Astrophysics Data System (ADS)

    Mendoza, M.; Herrmann, H. J.; Succi, S.

    2015-09-01

    Recently, a new connection between density functional theory and kinetic theory has been proposed. In particular, it was shown that the Kohn-Sham (KS) equations can be reformulated as a macroscopic limit of the steady-state solution of a suitable single-particle kinetic equation. By using a discrete version of this new formalism, the exchange and correlation energies of simple atoms and the geometrical configuration of the methane molecule were calculated accurately. Here, we discuss the main ideas behind the lattice kinetic approach to electronic structure computations, offer some considerations for prospective extensions, and also show additional numerical results, namely the geometrical configuration of the water molecule.

  2. Aromatic Structure in Simulates Titan Aerosol

    NASA Technical Reports Server (NTRS)

    Trainer, Melissa G.; Loeffler, M. J.; Anderson, C. M.; Hudson, R. L.; Samuelson, R. E.; Moore, M. A.

    2011-01-01

    Observations of Titan by the Cassini Composite Infrared Spectrometer (CIRS) between 560 and 20 per centimeter (approximately 18 to 500 micrometers) have been used to infer the vertical variations of Titan's ice abundances, as well as those of the aerosol from the surface to an altitude of 300 km [1]. The aerosol has a broad emission feature centered approximately at 140 per centimeter (71 micrometers). As seen in Figure 1, this feature cannot be reproduced using currently available optical constants from laboratory-generated Titan aerosol analogs [2]. The far-IR is uniquely qualified for investigating low-energy vibrational motions within the lattice structures of COITIDlex aerosol. The feature observed by CIRS is broad, and does not likely arise from individual molecules, but rather is representative of the skeletal movements of macromolecules. Since Cassini's arrival at Titan, benzene (C6H6) has been detected in the atmosphere at ppm levels as well as ions that may be polycyclic aromatic hydrocarbons (PAHs) [3]. We speculate that the feature may be a blended composite that can be identified with low-energy vibrations of two-dimensional lattice structures of large molecules, such as PAHs or nitrogenated aromatics. Such structures do not dominate the composition of analog materials generated from CH4 and N2 irradiation. We are performing studies forming aerosol analog via UV irradiation of aromatic precursors - specifically C6H6 - to understand how the unique chemical architecture of the products will influence the observable aerosol characteristics. The optical and chemical properties of the aromatic analog will be compared to those formed from CH4/N2 mixtures, with a focus on the as-yet unidentified far-IR absorbance feature. Preliminary results indicate that the photochemically-formed aromatic aerosol has distinct chemical composition, and may incorporate nitrogen either into the ring structure or adjoined chemical groups. These compositional differences are

  3. PARTNERSHIP FOR THE DEVELOPMENT OF NEXT GENERATION SIMULATION TOOLS TO EVALUATE CEMENTITIOUS BARRIERS AND MATERIALS USED IN NUCLEAR APPLICATION - 8388

    SciTech Connect

    Langton, C; Richard Dimenna, R

    2008-01-29

    The US DOE has initiated a multidisciplinary cross cutting project to develop a reasonable and credible set of tools to predict the structural, hydraulic and chemical performance of cement barriers used in nuclear applications over extended time frames (e.g., > 100 years for operating facilities and > 1000 years for waste management). A partnership that combines DOE, NRC, academia, private sector, and international expertise has been formed to accomplish the project objectives by integrating existing information and realizing advancements where necessary. The set of simulation tools and data developed under this project will be used to evaluate and predict the behavior of cementitious barriers used in near surface engineered waste disposal systems, e.g., waste forms, containment structures, entombments and environmental remediation, including decontamination and decommissioning (D&D) activities. The simulation tools will also support analysis of structural concrete components of nuclear facilities (spent fuel pools, dry spent fuel storage units, and recycling facilities, e.g., fuel fabrication, separations processes). Simulation parameters will be obtained from prior literature and will be experimentally measured under this project, as necessary, to demonstrate application of the simulation tools for three prototype applications (waste form in concrete vault, high level waste tank grouting, and spent fuel pool). Test methods and data needs to support use of the simulation tools for future applications will be defined. This is a national issue that affects all waste disposal sites that use cementitious waste forms and structures, decontamination and decommissioning activities, service life determination of existing structures, and design of future public and private nuclear facilities. The problem is difficult because it requires projecting conditions and responses over extremely long times. Current performance assessment analyses show that engineered barriers are

  4. Digital Full-Scope Simulation of a Conventional Nuclear Power Plant Control Room, Phase 2: Installation of a Reconfigurable Simulator to Support Nuclear Plant Sustainability

    SciTech Connect

    Ronald L. Boring; Vivek Agarwal; Kirk Fitzgerald; Jacques Hugo; Bruce Hallbert

    2013-03-01

    The U.S. Department of Energy’s Light Water Reactor Sustainability program has developed a control room simulator in support of control room modernization at nuclear power plants in the U.S. This report highlights the recent completion of this reconfigurable, full-scale, full-scope control room simulator buildout at the Idaho National Laboratory. The simulator is fully reconfigurable, meaning it supports multiple plant models developed by different simulator vendors. The simulator is full-scale, using glasstop virtual panels to display the analog control boards found at current plants. The present installation features 15 glasstop panels, uniquely achieving a complete control room representation. The simulator is also full-scope, meaning it uses the same plant models used for training simulators at actual plants. Unlike in the plant training simulators, the deployment on glasstop panels allows a high degree of customization of the panels, allowing the simulator to be used for research on the design of new digital control systems for control room modernization. This report includes separate sections discussing the glasstop panels, their layout to mimic control rooms at actual plants, technical details on creating a multi-plant and multi-vendor reconfigurable simulator, and current efforts to support control room modernization at U.S. utilities. The glasstop simulator provides an ideal testbed for prototyping and validating new control room concepts. Equally importantly, it is helping create a standardized and vetted human factors engineering process that can be used across the nuclear industry to ensure control room upgrades maintain and even improve current reliability and safety.

  5. Crystal Structure of the Herpesvirus Nuclear Egress Complex Provides Insights into Inner Nuclear Membrane Remodeling

    PubMed Central

    Zeev-Ben-Mordehai, Tzviya; Weberruß, Marion; Lorenz, Michael; Cheleski, Juliana; Hellberg, Teresa; Whittle, Cathy; El Omari, Kamel; Vasishtan, Daven; Dent, Kyle C.; Harlos, Karl; Franzke, Kati; Hagen, Christoph; Klupp, Barbara G.; Antonin, Wolfram; Mettenleiter, Thomas C.; Grünewald, Kay

    2015-01-01

    Summary Although nucleo-cytoplasmic transport is typically mediated through nuclear pore complexes, herpesvirus capsids exit the nucleus via a unique vesicular pathway. Together, the conserved herpesvirus proteins pUL31 and pUL34 form the heterodimeric nuclear egress complex (NEC), which, in turn, mediates the formation of tight-fitting membrane vesicles around capsids at the inner nuclear membrane. Here, we present the crystal structure of the pseudorabies virus NEC. The structure revealed that a zinc finger motif in pUL31 and an extensive interaction network between the two proteins stabilize the complex. Comprehensive mutational analyses, characterized both in situ and in vitro, indicated that the interaction network is not redundant but rather complementary. Fitting of the NEC crystal structure into the recently determined cryoEM-derived hexagonal lattice, formed in situ by pUL31 and pUL34, provided details on the molecular basis of NEC coat formation and inner nuclear membrane remodeling. PMID:26711332

  6. COMPUTER SIMULATIONS OF HUMAN LUNG STRUCTURES FOR MEDICAL APPLICATIONS

    EPA Science Inventory

    Knowledge of the structure of the human lung has salient health effects applications. he clinical issues encompass (1) aerosol therapy, delivery of inhaled particles to enhance the efficacies of pharmacologic drugs, and (2) nuclear medicine, where planar gamma camera imaging, SPE...

  7. Unified ab initio approaches to nuclear structure and reactions

    NASA Astrophysics Data System (ADS)

    Navrátil, Petr; Quaglioni, Sofia; Hupin, Guillaume; Romero-Redondo, Carolina; Calci, Angelo

    2016-05-01

    The description of nuclei starting from the constituent nucleons and the realistic interactions among them has been a long-standing goal in nuclear physics. In addition to the complex nature of the nuclear forces, with two-, three- and possibly higher many-nucleon components, one faces the quantum-mechanical many-nucleon problem governed by an interplay between bound and continuum states. In recent years, significant progress has been made in ab initio nuclear structure and reaction calculations based on input from QCD-employing Hamiltonians constructed within chiral effective field theory. After a brief overview of the field, we focus on ab initio many-body approaches—built upon the no-core shell model—that are capable of simultaneously describing both bound and scattering nuclear states, and present results for resonances in light nuclei, reactions important for astrophysics and fusion research. In particular, we review recent calculations of resonances in the 6He halo nucleus, of five- and six-nucleon scattering, and an investigation of the role of chiral three-nucleon interactions in the structure of 9Be. Further, we discuss applications to the 7Be {({{p}},γ )}8{{B}} radiative capture. Finally, we highlight our efforts to describe transfer reactions including the 3H{({{d}},{{n}})}4He fusion.

  8. Geomechanical numerical simulations of complex geologic structures

    SciTech Connect

    Arguello, J.G.; Stone, C.M.; Lorenz, J.C.

    1996-05-01

    Ability to predict mechanical response of rock in three dimensions over the spatial and time scales of geologic interest would give the oil and gas industry the ability to reduce risk on prospects, improve pre-project initial reserve estimates, and lower operating costs. A program has recently been initiated, under the auspices of the Advanced Computational Technology Initiative (ACTI), to achieve such a computational technology breakthrough by adapting the unique advanced quasistatic finite element technology developed by Sandia to the mechanics applications important to exploration and production activities within the oil and gas industry. As a precursor to that program, in an effort to evaluate the feasibility of the approach, several complex geologic structures of interest were analyzed with the existing two-dimensional quasistatic finite element code, SANTOS, developed at Sandia. Examples are presented and discussed.

  9. Modeling Choices in Nuclear Warfighting: Two Classroom Simulations on Escalation and Retaliation

    ERIC Educational Resources Information Center

    Schofield, Julian

    2013-01-01

    Two classroom simulations--"Superpower Confrontation" and "Multipolar Asian Simulation"--are used to teach and test various aspects of the Borden versus Brodie debate on the Schelling versus Lanchester approach to nuclear conflict modeling and resolution. The author applies a Schelling test to segregate high from low empathic students, and assigns…

  10. In situ structural analysis of the human nuclear pore complex

    PubMed Central

    Ori, Alessandro; DiGuilio, Amanda L.; Vollmer, Benjamin; Mackmull, Marie-Therese; Banterle, Niccolo; Parca, Luca; Kastritis, Panagiotis; Buczak, Katarzyna; Mosalaganti, Shyamal; Hagen, Wim; Andres-Pons, Amparo; Lemke, Edward A.; Bork, Peer; Antonin, Wolfram; Glavy, Joseph S.; Bui, Khanh Huy; Beck, Martin

    2016-01-01

    Summary Nuclear pore complexes (NPCs) are fundamental components of all eukaryotic cells that mediate nucleocytoplasmic exchange. Elucidating their 110 MDa structure imposes a formidable challenge and requires in situ structural biology approaches. Fifteen out of about thirty nucleoporins (Nups) are structured and form the Y- and inner ring complexes. These two major scaffolding modules assemble in multiple copies into an eight-fold rotationally symmetric structure that fuses the inner and outer nuclear membranes to form a central channel of ∼60 nm in diameter 1. The scaffold is decorated with transport channel Nups that often contain phenylalanine (FG)-repeat sequences and mediate the interaction with cargo complexes. Although the architectural arrangement of parts of the Y-complex has been elucidated, it is unclear how exactly it oligomerizes in situ. Here, we combined cryo electron tomography with mass spectrometry, biochemical analysis, perturbation experiments and structural modeling to generate the most comprehensive architectural model of the NPC to date. Our data suggest previously unknown protein interfaces across Y-complexes and to inner ring complex members. We demonstrate that the higher eukaryotic transport channel Nup358 (RanBP2) has a previously unanticipated role in Y-complex oligomerization. Our findings blur the established boundaries between scaffold and transport channel Nups. We conclude that, similarly to coated vesicles, multiple copies of the same structural building block - although compositionally identical - engage in different local sets of interactions and conformations. PMID:26416747

  11. Development of High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing

    SciTech Connect

    Bragg-Sitton, Shannon M.; Dickens, Ricky; Adams, Mike; Davis, Joe; Kapernick, Richard

    2007-01-30

    Non-nuclear testing can be a valuable tool in the development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Work at the NASA Marshall Space Flight Center seeks to develop high fidelity thermal simulators that not only match the static power profile that would be observed in an operating, fueled nuclear reactor, but also match the dynamic fuel pin performance during feasible transients. Comparison between the fuel pins and thermal simulators is made at the outer fuel clad surface, which corresponds to the outer sheath surface in the thermal simulator. The thermal simulators that are currently being developed are designed to meet the geometric and power requirements of a proposed surface power reactor design, accommodate testing of various axial power profiles, and incorporate imbedded instrumentation. Static and dynamic fuel pin performances for a proposed reactor design have been determined using SINDA/FLUINT thermal analysis software, and initial comparison has been made between the expected nuclear performance and the performance of conceptual thermal simulator designs. Through a series of iterative analysis, a conceptual high fidelity design will be developed, followed by engineering design, fabrication, and testing to validate the overall design process. Although the resulting thermal simulator will be designed for a specific reactor concept, establishing this rigorous design process will assist in streamlining the thermal simulator development for other reactor concepts. This paper presents the current status of high fidelity thermal simulator design relative to a SNAP derivative reactor design that could be applied for Lunar surface power.

  12. Formation of coherent structures in kinetic simulations of collisionless turbulence

    NASA Astrophysics Data System (ADS)

    Roytershteyn, V.; Karimabadi, H.

    2014-12-01

    We discuss recent large-scale kinetic simulations of collisionless turbulence in two environments, the solar wind and the Earth's magnetosheath. Formation of copious coherent structures is observed in both cases, despite the facts that the geometry, characteristic plasma parameters, and driving mechanisms are drastically different between the two systems. In addition to the traditional planar current sheets, other types of coherent current structures have been observed in 3D fully kinetic simulations with initial conditions relevant to the solar wind. These structures are discussed in detail. In 3D global hybrid simulations of the interaction between solar wind and planetary magnetospheres, the foreshock dynamics driven by reflected ions is shown to have a significant impact on the structure of the bow shock, as well as on the magnetosheath turbulence. A complicated interaction between turbulence, bow shock, and global flow leads to global perturbations in the Earth's magnetosphere.

  13. Structure and dynamics of complex liquid water: Molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    S, Indrajith V.; Natesan, Baskaran

    2015-06-01

    We have carried out detailed structure and dynamical studies of complex liquid water using molecular dynamics simulations. Three different model potentials, namely, TIP3P, TIP4P and SPC-E have been used in the simulations, in order to arrive at the best possible potential function that could reproduce the structure of experimental bulk water. All the simulations were performed in the NVE micro canonical ensemble using LAMMPS. The radial distribution functions, gOO, gOH and gHH and the self diffusion coefficient, Ds, were calculated for all three models. We conclude from our results that the structure and dynamical parameters obtained for SPC-E model matched well with the experimental values, suggesting that among the models studied here, the SPC-E model gives the best structure and dynamics of bulk water.

  14. Ab initio nuclear structure from lattice effective field theory

    SciTech Connect

    Lee, Dean

    2014-11-11

    This proceedings article reviews recent results by the Nuclear Lattice EFT Collaboration on an excited state of the {sup 12}C nucleus known as the Hoyle state. The Hoyle state plays a key role in the production of carbon via the triple-alpha reaction in red giant stars. We discuss the structure of low-lying states of {sup 12}C as well as the dependence of the triple-alpha reaction on the masses of the light quarks.

  15. EVALUATED NUCLEAR STRUCTURE DATA FILE -- A MANUAL FOR PREPARATION OF DATA SETS.

    SciTech Connect

    TULI, J.K.

    2001-02-01

    This manual describes the organization and structure of the Evaluated Nuclear Structure Data File (ENSDF). This computer-based file is maintained by the National Nuclear Data Center (NNDC) at Brookhaven National Laboratory for the international Nuclear Structure and Decay Data Network. For every mass number (presently, A {le} 293), the Evaluated Nuclear Structure Data File (ENSDF) contains evaluated structure information. For masses A {ge} 44, this information is published in the Nuclear Data Sheets; for A < 44, ENSDF is based on compilations published in the journal Nuclear Physics. The information in ENSDF is updated by mass chain or by nuclide with a varying cycle time dependent on the availability of new information.

  16. Evaluated nuclear structure data file: A manual for preparation of data sets

    SciTech Connect

    Tuli, J.K.

    1987-04-01

    This manual describes the organization and structure of the Evaluated Nuclear Structure Data File (ENSDF). This computer-based file is maintained by the National Nuclear Data Center (NNDC) at Brookhaven National Laboratory for the international Nuclear Structure and Decay Data Network. For every mass number (presently, Aless than or equal to263), the Evaluated Nuclear Structure Data File (ENSDF) contains evaluated structure information. For masses Agreater than or equal to45, this information is documented in the Nuclear Data Sheets; for A<45, ENSDF is based on compilations published in the journal Nuclear Physics. The information in ENSDF is updated by mass chains with a present cycle time of approximately six years.

  17. Modeling and numerical techniques for high-speed digital simulation of nuclear power plants

    SciTech Connect

    Wulff, W.; Cheng, H.S.; Mallen, A.N.

    1987-01-01

    Conventional computing methods are contrasted with newly developed high-speed and low-cost computing techniques for simulating normal and accidental transients in nuclear power plants. Six principles are formulated for cost-effective high-fidelity simulation with emphasis on modeling of transient two-phase flow coolant dynamics in nuclear reactors. Available computing architectures are characterized. It is shown that the combination of the newly developed modeling and computing principles with the use of existing special-purpose peripheral processors is capable of achieving low-cost and high-speed simulation with high-fidelity and outstanding user convenience, suitable for detailed reactor plant response analyses.

  18. High-speed simulation of transients in nuclear power plants

    SciTech Connect

    Wulff, W.; Cheng, H.S.; Lekach, S.V.; Mallen, A.N.

    1984-01-01

    A combination of advanced modeling techniques and modern, special-purpose peripheral minicomputer technology is presented which affords realistic predictions of plant transient and severe off-normal events in LWR power plants through on-line simulations at a speed ten times greater than actual process speeds. Results are shown for a BWR plant simulation. Results are shown to demonstrate computing capacity, accuracy, and speed. Simulation speeds have been achieved which are 110 times larger than those of a CDC-7600 mainframe computer or ten times greater than real-time speed.

  19. Response analysis of a nuclear containment structure with nonlinear soil-structure interaction under bi-directional ground motion

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Raychowdhury, Prishati; Gundlapalli, Prabhakar

    2015-06-01

    Design of critical facilities such as nuclear power plant requires an accurate and precise evaluation of seismic demands, as any failure of these facilities poses immense threat to the community. Design complexity of these structures reinforces the necessity of a robust 3D modeling and analysis of the structure and the soil-foundation interface. Moreover, it is important to consider the multiple components of ground motion during time history analysis for a realistic simulation. Present study is focused on investigating the seismic response of a nuclear containment structure considering nonlinear Winkler-based approach to model the soil-foundation interface using a distributed array of inelastic springs, dashpots and gap elements. It is observed from this study that the natural period of the structure increases about 10 %, whereas the force demands decreases up to 24 % by considering the soil-structure interaction. Further, it is observed that foundation deformations, such as rotation and sliding are affected by the embedment ratio, indicating an increase of up to 56 % in these responses for a reduction of embedment from 0.5 to 0.05× the width of the footing.

  20. Nuclear structure of 122-134Ba in IBM-1

    NASA Astrophysics Data System (ADS)

    Gupta, J. B.

    2015-04-01

    The nuclear level structures of 122-134 Ba isotopes have been studied empirically in relation to the analytic symmetries of the interacting boson model IBM-1 and in the calculation of the IBM-1 Hamiltonian. Comparison is made with experiment and with the microscopic dynamic pairing plus quadrupole model predictions available from our previous studies. The variation of the structure of states in the 22 + bands and of the 0{2,3/+} bands, with neutron number N, have been studied. Relation of odd-even spin staggering in the 22 + bands with the β-softness is illustrated. A comparison is made with predictions of the various analytical symmetries.

  1. Evaluation and Numerical Simulation of Tsunami for Coastal Nuclear Power Plants of India

    SciTech Connect

    Sharma, Pavan K.; Singh, R.K.; Ghosh, A.K.; Kushwaha, H.S.

    2006-07-01

    Recent tsunami generated on December 26, 2004 due to Sumatra earthquake of magnitude 9.3 resulted in inundation at the various coastal sites of India. The site selection and design of Indian nuclear power plants demand the evaluation of run up and the structural barriers for the coastal plants: Besides it is also desirable to evaluate the early warning system for tsunami-genic earthquakes. The tsunamis originate from submarine faults, underwater volcanic activities, sub-aerial landslides impinging on the sea and submarine landslides. In case of a submarine earthquake-induced tsunami the wave is generated in the fluid domain due to displacement of the seabed. There are three phases of tsunami: generation, propagation, and run-up. Reactor Safety Division (RSD) of Bhabha Atomic Research Centre (BARC), Trombay has initiated computational simulation for all the three phases of tsunami source generation, its propagation and finally run up evaluation for the protection of public life, property and various industrial infrastructures located on the coastal regions of India. These studies could be effectively utilized for design and implementation of early warning system for coastal region of the country apart from catering to the needs of Indian nuclear installations. This paper presents some results of tsunami waves based on different analytical/numerical approaches with shallow water wave theory. (authors)

  2. The harmony between nuclear reactions and nuclear reactor structures and systems

    SciTech Connect

    Popa-Simil, L.

    2012-07-01

    Advanced nuclear energy is one extremely viable approach for achieving the required goals. With its extraordinarily high energy density (both, per unit mass and per unit volume), it produces over seven orders of magnitude less waste than fossil fuels per unit of energy generated. Applying nano-technologies to nuclear reactors could potentially produce the extraordinary performance required. The actual nuclear reactors lack of performances, the complexity and hazard of the fuel cycle are in part due to the lack of understanding of the nature's laws related to energy distribution applied to fission products, and in part to the current technologic capabilities that make the economical optimum. In order to produce the desired increase of performances a novel multi-scale multi-physics and engineering approach have been developed, starting from the nuclear reactions involved, analyzing in detail the key features and requirements of the 'key players' in the process (neutrons, compound nucleus, fission products, transmutation products, decay radiation), the consequences of their interaction with matter. That complex interaction generates new reactions and new key-players (knock-on electrons, photons, phonons) that further interact with the matter represented by the nuclear fuel, cladding, cooling agents, structural materials and control systems. The understanding of this complexity of problems from fm-ps scale up to macro-system and mitigating all the requirements drives to that desired harmony that provides a safe energy delivery. (authors)

  3. Evaluated Nuclear Structure Data File (ENSDF) from the National Nuclear Data Center (NNDC)

    DOE Data Explorer

    ENSDF contains evaluated nuclear structure and decay data in a standard format. An international network of evaluators contributes to the database, which is maintained by the National Nuclear Data Center at Brookhaven National Laboratory. Information in the database is regularly updated to reflect revised evaluation results. Most of the recently completed evaluations are published in Nuclear Data Sheets, a monthly journal published by Academic Press, a division of Elsevier Science. For each nuclide, all known experimental data used to deduce nuclear structure information are included. Each type of experiment is presented as a separate dataset. In addition, there is a dataset of "adopted" level and gamma-ray transition properties, which represent the evaluator's determination of the best values for these properties, based on all available experimental data. As of February 2008, the ENSDF database contains 16236 datasets for 3030 nuclides. (Taken from the NNDC's information page on ENSDF at http://www.nndc.bnl.gov/ensdf/ensdf_info.jsp) ENSDF may be browsed or the data may be retrieved based on nuclide, charge, or mass, or by indexed reaction and decay quantities. (Specialized interface)

  4. FTIR spectra and properties of iron borophosphate glasses containing simulated nuclear wastes

    NASA Astrophysics Data System (ADS)

    Liao, Qilong; Wang, Fu; Chen, Kuiru; Pan, Sheqi; Zhu, Hanzhen; Lu, Mingwei; Qin, Jianfa

    2015-07-01

    30 wt.% simulated nuclear wastes were successfully immobilized by B2O3-doped iron phosphate base glasses. The structure and thermal stability of the prepared wasteforms were characterized by Fourier transform infrared spectroscopy and differential thermal analysis, respectively. The subtle structural variations attributed to different B2O3 doping modes have been discussed in detail. The results show that the thermal stability and glass forming tendency of the iron borophosphate glass wasteforms are faintly affected by different B2O3 doping modes. The main structural networks of iron borophosphate glass wasteforms are PO43-, P2O74-, [BO4] groups. Furthermore, for the wasteform prepared by using 10B2O3-36Fe2O3-54P2O5 as base glass, the distributions of Fe-O-P bonds, [BO4], PO43- and P2O74- groups are optimal. In general, the dissolution rate (DR) values of the studied iron borophosphate wasteforms are about 10-8 g cm-2 min-1. The obtained conclusions can offer some useful information for the disposal of high-level radioactive wastes using boron contained phosphate glasses.

  5. Computational simulation for analysis and synthesis of impact resilient structure

    NASA Astrophysics Data System (ADS)

    Djojodihardjo, Harijono

    2013-10-01

    Impact resilient structures are of great interest in many engineering applications varying from civil, land vehicle, aircraft and space structures, to mention a few examples. To design such structure, one has to resort fundamental principles and take into account progress in analytical and computational approaches as well as in material science and technology. With such perspectives, this work looks at a generic beam and plate structure subject to impact loading and carry out analysis and numerical simulation. The first objective of the work is to develop a computational algorithm to analyze flat plate as a generic structure subjected to impact loading for numerical simulation and parametric study. The analysis will be based on dynamic response analysis. Consideration is given to the elastic-plastic region. The second objective is to utilize the computational algorithm for direct numerical simulation, and as a parallel scheme, commercial off-the shelf numerical code is utilized for parametric study, optimization and synthesis. Through such analysis and numerical simulation, effort is devoted to arrive at an optimum configuration in terms of loading, structural dimensions, material properties and composite lay-up, among others. Results will be discussed in view of practical applications.

  6. Mathematical analysis of compressive/tensile molecular and nuclear structures

    NASA Astrophysics Data System (ADS)

    Wang, Dayu

    Mathematical analysis in chemistry is a fascinating and critical tool to explain experimental observations. In this dissertation, mathematical methods to present chemical bonding and other structures for many-particle systems are discussed at different levels (molecular, atomic, and nuclear). First, the tetrahedral geometry of single, double, or triple carbon-carbon bonds gives an unsatisfying demonstration of bond lengths, compared to experimental trends. To correct this, Platonic solids and Archimedean solids were evaluated as atoms in covalent carbon or nitrogen bond systems in order to find the best solids for geometric fitting. Pentagonal solids, e.g. the dodecahedron and icosidodecahedron, give the best fit with experimental bond lengths; an ideal pyramidal solid which models covalent bonds was also generated. Second, the macroscopic compression/tension architectural approach was applied to forces at the molecular level, considering atomic interactions as compressive (repulsive) and tensile (attractive) forces. Two particle interactions were considered, followed by a model of the dihydrogen molecule (H2; two protons and two electrons). Dihydrogen was evaluated as two different types of compression/tension structures: a coaxial spring model and a ring model. Using similar methods, covalent diatomic molecules (made up of C, N, O, or F) were evaluated. Finally, the compression/tension model was extended to the nuclear level, based on the observation that nuclei with certain numbers of protons/neutrons (magic numbers) have extra stability compared to other nucleon ratios. A hollow spherical model was developed that combines elements of the classic nuclear shell model and liquid drop model. Nuclear structure and the trend of the "island of stability" for the current and extended periodic table were studied.

  7. Controlled multibody dynamics simulation for large space structures

    NASA Technical Reports Server (NTRS)

    Housner, J. M.; Wu, S. C.; Chang, C. W.

    1989-01-01

    Multibody dynamics discipline, and dynamic simulation in control structure interaction (CSI) design are discussed. The use, capabilities, and architecture of the Large Angle Transient Dynamics (LATDYN) code as a simulation tool are explained. A generic joint body with various types of hinge connections; finite element and element coordinate systems; results of a flexible beam spin-up on a plane; mini-mast deployment; space crane and robotic slewing manipulations; a potential CSI test article; and multibody benchmark experiments are also described.

  8. Stochastic search in structural optimization - Genetic algorithms and simulated annealing

    NASA Technical Reports Server (NTRS)

    Hajela, Prabhat

    1993-01-01

    An account is given of illustrative applications of genetic algorithms and simulated annealing methods in structural optimization. The advantages of such stochastic search methods over traditional mathematical programming strategies are emphasized; it is noted that these methods offer a significantly higher probability of locating the global optimum in a multimodal design space. Both genetic-search and simulated annealing can be effectively used in problems with a mix of continuous, discrete, and integer design variables.

  9. The Molecular Mechanism of Bisphenol A (BPA) as an Endocrine Disruptor by Interacting with Nuclear Receptors: Insights from Molecular Dynamics (MD) Simulations

    PubMed Central

    Li, Lanlan; Wang, Qianqian; Zhang, Yan; Niu, Yuzhen; Yao, Xiaojun; Liu, Huanxiang

    2015-01-01

    Bisphenol A (BPA) can interact with nuclear receptors and affect the normal function of nuclear receptors in very low doses, which causes BPA to be one of the most controversial endocrine disruptors. However, the detailed molecular mechanism about how BPA interferes the normal function of nuclear receptors is still undiscovered. Herein, molecular dynamics simulations were performed to explore the detailed interaction mechanism between BPA with three typical nuclear receptors, including hERα, hERRγ and hPPARγ. The simulation results and calculated binding free energies indicate that BPA can bind to these three nuclear receptors. The binding affinities of BPA were slightly lower than that of E2 to these three receptors. The simulation results proved that the binding process was mainly driven by direct hydrogen bond and hydrophobic interactions. In addition, structural analysis suggested that BPA could interact with these nuclear receptors by mimicking the action of natural hormone and keeping the nuclear receptors in active conformations. The present work provided the structural evidence to recognize BPA as an endocrine disruptor and would be important guidance for seeking safer substitutions of BPA. PMID:25799048

  10. Simulating semiconductor structures for next-generation optical inspection technologies

    NASA Astrophysics Data System (ADS)

    Golani, Ori; Dolev, Ido; Pond, James; Niegemann, Jens

    2016-02-01

    We present a technique for optimizing advanced optical imaging methods for nanoscale structures, such as those encountered in the inspection of cutting-edge semiconductor devices. The optimization flow is divided to two parts: simulating light-structure interaction using the finite-difference time-domain (FDTD) method and simulating the optical imaging system by means of its optical transfer function. As a case study, FDTD is used to simulate 10-nm silicon line-space and static random-access memory patterns, with irregular structural protrusions and silicon-oxide particles as defects of interest. An ultraviolet scanning-spot optical microscope is used to detect these defects, and the optimization flow is used to find the optimal imaging mode for detection.

  11. Impact and Penetration Simulations for Composite Wing-like Structures

    NASA Technical Reports Server (NTRS)

    Knight, Norman F.

    1998-01-01

    The goal of this research project was to develop methodologies for the analysis of wing-like structures subjected to impact loadings. Low-speed impact causing either no damage or only minimal damage and high-speed impact causing severe laminate damage and possible penetration of the structure were to be considered during this research effort. To address this goal, an assessment of current analytical tools for impact analysis was performed. Assessment of the analytical tools for impact and penetration simulations with regard to accuracy, modeling, and damage modeling was considered as well as robustness, efficient, and usage in a wing design environment. Following a qualitative assessment, selected quantitative evaluations will be performed using the leading simulation tools. Based on this assessment, future research thrusts for impact and penetration simulation of composite wing-like structures were identified.

  12. 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

  13. Exploring Nuclear Effects in the Dynamics of Nanomaterials with a Quantum Trajectory-Electronic Structure Approach

    NASA Astrophysics Data System (ADS)

    Garashchuk, Sophya

    2014-03-01

    A massively parallel, direct quantum molecular dynamics method is described. The method combines a quantum trajectory (QT) representation of the nuclear wavefunction discretized into an ensemble of trajectories with an electronic structure (ES) description of electrons, namely using the Density Functional Tight Binding (DFTB) theory. Quantum nuclear effects are included into the dynamics of the nuclei via quantum corrections to the classical forces. To reduce computational cost and increase numerical accuracy, the quantum corrections to dynamics resulting from localization of the nuclear wavefunction are computed approximately and included into selected degrees of freedom representing light particles where the quantum effects are expected to be the most pronounced. A massively parallel implementation, based on the Message Passing Interface allows for efficient simulations of ensembles of thousands of trajectories at once. The QTES-DFTB dynamics approach is employed to study the role of quantum nuclear effects on the interaction of hydrogen with a model graphene sheet, revealing that neglect of nuclear effects can lead to an overestimation of adsorption. Supported by the National Science Foundation and the Petroleum Research Fund of the American Chemical Society.

  14. Research in nondestructive evaluation techniques for nuclear reactor concrete structures

    SciTech Connect

    Clayton, Dwight; Smith, Cyrus

    2014-02-18

    The purpose of the Materials Aging and Degradation (MAaD) Pathway of the Department of Energy's Light Water Reactor Sustainability (LWRS) Program is to develop the scientific basis for understanding and predicting longterm environmental degradation behavior of material in nuclear power plants and to provide data and methods to assess the performance of systems, structures, and components (SSCs) essential to safe and sustained nuclear power plant operations. The understanding of aging-related phenomena and their impacts on SSCs is expected to be a significant issue for any nuclear power plant planning for long-term operations (i.e. service beyond the initial license renewal period). Management of those phenomena and their impacts during long-term operations can be better enable by improved methods and techniques for detection, monitoring, and prediction of SSC degradation. The MAaD Pathway R and D Roadmap for Concrete, 'Light Water Reactor Sustainability Nondestructive Evaluation for Concrete Research and Development Roadmap', focused initial research efforts on understanding the recent concrete issues at nuclear power plants and identifying the availability of concrete samples for NDE techniques evaluation and testing. [1] An overview of the research performed by ORNL in these two areas is presented here.

  15. Research in nondestructive evaluation techniques for nuclear reactor concrete structures

    NASA Astrophysics Data System (ADS)

    Clayton, Dwight; Smith, Cyrus

    2014-02-01

    The purpose of the Materials Aging and Degradation (MAaD) Pathway of the Department of Energy's Light Water Reactor Sustainability (LWRS) Program is to develop the scientific basis for understanding and predicting longterm environmental degradation behavior of material in nuclear power plants and to provide data and methods to assess the performance of systems, structures, and components (SSCs) essential to safe and sustained nuclear power plant operations. The understanding of aging-related phenomena and their impacts on SSCs is expected to be a significant issue for any nuclear power plant planning for long-term operations (i.e. service beyond the initial license renewal period). Management of those phenomena and their impacts during long-term operations can be better enable by improved methods and techniques for detection, monitoring, and prediction of SSC degradation. The MAaD Pathway R&D Roadmap for Concrete, "Light Water Reactor Sustainability Nondestructive Evaluation for Concrete Research and Development Roadmap", focused initial research efforts on understanding the recent concrete issues at nuclear power plants and identifying the availability of concrete samples for NDE techniques evaluation and testing. [1] An overview of the research performed by ORNL in these two areas is presented here.

  16. Numerical Simulation of Flow-Induced Structure in Complex Fluids

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takehiro

    2007-04-01

    It is important to investigate the flow-induced structure for the analysis of the mechanism of flow behavior of complex fluids. The present paper includes two topics in which the flow-induced structure is numerically investigated. The first topic treats the suspensions of disc-like particles under simple shear flows. Disc-like particles were modeled by oblate spheroid particles, and the Brownian dynamics simulation was performed for suspensions of the particles interacting via the Gay-Berne potential. This simulation confirmed that this model system was applicable to the analysis of flow of suspension of disc-like particles. The second one is the numerical simulation of the deformation behavior of a droplet in shear flows. The present simulation is the first step for the numerical simulation of the flow-induced structure in emulsions. This simulation can demonstrate the deformation behavior of droplet observed in experiments and predict effects of non-Newtonian property of fluids on the droplet deformation.

  17. KEYNOTE: Simulation, computation, and the Global Nuclear Energy Partnership

    NASA Astrophysics Data System (ADS)

    Reis, Victor, Dr.

    2006-01-01

    Dr. Victor Reis delivered the keynote talk at the closing session of the conference. The talk was forward looking and focused on the importance of advanced computing for large-scale nuclear energy goals such as Global Nuclear Energy Partnership (GNEP). Dr. Reis discussed the important connections of GNEP to the Scientific Discovery through Advanced Computing (SciDAC) program and the SciDAC research portfolio. In the context of GNEP, Dr. Reis talked about possible fuel leasing configurations, strategies for their implementation, and typical fuel cycle flow sheets. A major portion of the talk addressed lessons learnt from ‘Science Based Stockpile Stewardship’ and the Accelerated Strategic Computing Initiative (ASCI) initiative and how they can provide guidance for advancing GNEP and SciDAC goals. Dr. Reis’s colorful and informative presentation included international proverbs, quotes and comments, in tune with the international flavor that is part of the GNEP philosophy and plan. He concluded with a positive and motivating outlook for peaceful nuclear energy and its potential to solve global problems. An interview with Dr. Reis, addressing some of the above issues, is the cover story of Issue 2 of the SciDAC Review and available at http://www.scidacreview.org This summary of Dr. Reis’s PowerPoint presentation was prepared by Institute of Physics Publishing, the complete PowerPoint version of Dr. Reis’s talk at SciDAC 2006 is given as a multimedia attachment to this summary.

  18. Fire simulation in nuclear facilities: the FIRAC code and supporting experiments

    SciTech Connect

    Burkett, M.W.; Martin, R.A.; Fenton, D.L.; Gunaji, M.V.

    1984-01-01

    The fire accident analysis computer code FIRAC was designed to estimate radioactive and nonradioactive source terms and predict fire-induced flows and thermal and material transport within the ventilation systems of nuclear fuel cycle facilities. FIRAC maintains its basic structure and features and has been expanded and modified to include the capabilities of the zone-type compartment fire model computer code FIRIN developed by Battelle Pacific Northwest Laboratory. The two codes have been coupled to provide an improved simulation of a fire-induced transient within a facility. The basic material transport capability of FIRAC has been retained and includes estimates of entrainment, convection, deposition, and filtration of material. The interrelated effects of filter plugging, heat transfer, gas dynamics, material transport, and fire and radioactive source terms also can be simulated. Also, a sample calculation has been performed to illustrate some of the capabilities of the code and how a typical facility is modeled with FIRAC. In addition to the analytical work being performed at Los Alamos, experiments are being conducted at the New Mexico State University to support the FIRAC computer code development and verification. This paper summarizes two areas of the experimental work that support the material transport capabiities of the code: the plugging of high-efficiency particulate air (HEPA) filters by combustion aerosols and the transport and deposition of smoke in ventilation system ductwork.

  19. Pore structure development in oxidized IG-110 nuclear graphite

    SciTech Connect

    Wang, Peng; Contescu, Cristian I; Yu, Suyuan; Burchell, Timothy D

    2012-01-01

    The oxidation-induced porosity development in nuclear graphite has great effect on its mechanical behavior, thus it is very important to understand the pore structure development of nuclear graphite during oxidation. This paper reports on the oxidation kinetics of grade IG-110 nuclear graphite and the porosity development in oxidized samples. The distribution of the oxidized layer in IG-110 specimens oxidized at 600-750 C was studied using optical microscopy coupled with automated image analysis technique, and the mechanism of porosity development was determined. The thickness of oxidized layer decreased with the oxidation temperature but was independent of the weight loss level. Oxidation caused consumption of graphite structure and development of porosity, which was initiated from the binder phase. Statistical analysis indicated that generation and growth of pores was dominant at low temperatures, while merging and collapse of pores was the main effect at high temperatures. Compared with medium-grained PCEA graphite, the fine-grained IG-110 graphite demonstrates deeper penetration of the oxidant because of its higher pore density and lager porosity.

  20. Simulated tornado debris tracks: implications for inferring corner flow structure

    NASA Astrophysics Data System (ADS)

    Zimmerman, Michael; Lewellen, David

    2011-11-01

    A large collection of three-dimensional large eddy simulations of tornadoes with fine debris have been recently been performed as part of a longstanding effort at West Virginia University to understand tornado corner flow structure and dynamics. Debris removal and deposition is accounted for at the surface, in effect simulating formation of tornado surface marks. Physical origins and properties of the most prominent marks will be presented, and the possibility of inferring tornado corner flow structure from real marks in the field will be discussed. This material is based upon work supported by the National Science Foundation under Grants No. 0635681 and AGS-1013154.

  1. Simulation approach to understanding the processes that structure food webs

    SciTech Connect

    Jager, H.I.; Gardner, R.H.; DeAngelis, D.L.; Post, W.M.

    1984-08-01

    A simulation model of food web dynamics, WEB, was constructed and used in Monte Carlo experiments to study the relationship between structure and function in food webs. Four main experiments were designed using WEB. The first tested the robustness of food web structures at equilibrium to variations in the functional response of predators in the food web to the densities of their prey. The second experiment clarified the roles of predation and resource limitation in the process of structuring food webs. A third experiment studied the influence of productivity on food web structure and function using simulated food webs. The final experiment was designed to study the differential successes of generalists and specialists. The main advantage gained by using a simulation approach in each of these experiments was the ability to assess the roles played by processes of predation and competition in structuring model food webs. This was accomplished by interpreting the order of extinction events that occurred in the simulations and relating these to the species configurations at equilibrium. 61 references, 23 figures.

  2. Structural mechanism for signal transduction in RXR nuclear receptor heterodimers

    PubMed Central

    Kojetin, Douglas J.; Matta-Camacho, Edna; Hughes, Travis S.; Srinivasan, Sathish; Nwachukwu, Jerome C.; Cavett, Valerie; Nowak, Jason; Chalmers, Michael J.; Marciano, David P.; Kamenecka, Theodore M.; Shulman, Andrew I.; Rance, Mark; Griffin, Patrick R.; Bruning, John B.; Nettles, Kendall W.

    2015-01-01

    A subset of nuclear receptors (NRs) function as obligate heterodimers with retinoid X receptor (RXR), allowing integration of ligand-dependent signals across the dimer interface via an unknown structural mechanism. Using nuclear magnetic resonance (NMR) spectroscopy, x-ray crystallography and hydrogen/deuterium exchange (HDX) mass spectrometry, here we show an allosteric mechanism through which RXR co-operates with a permissive dimer partner, peroxisome proliferator-activated receptor (PPAR)-γ, while rendered generally unresponsive by a non-permissive dimer partner, thyroid hormone (TR) receptor. Amino acid residues that mediate this allosteric mechanism comprise an evolutionarily conserved network discovered by statistical coupling analysis (SCA). This SCA network acts as a signalling rheostat to integrate signals between dimer partners, ligands and coregulator-binding sites, thereby affecting signal transmission in RXR heterodimers. These findings define rules guiding how NRs integrate two ligand-dependent signalling pathways into RXR heterodimer-specific responses. PMID:26289479

  3. Nuclear structure studies with medium energy probes. [Northwestern Univ

    SciTech Connect

    Seth, Kamal K.

    1980-01-01

    Progress in the continuing program of experimental research in nuclear structure with medium-energy probes during the year 1979-1980 is reviewed, and the research activities planned for the year 1980-1981 are discussed. In the study of pion-induced reactions emphasis is placed on investigation of isovector characteristics of nuclear excitations and on double charge exchange reactions. Pion production studies form the major part of the program of experiments with proton beams of 400 to 800 MeV at LAMPF. Current emphasis is on the bearing of these investigations on di-baryon existence. The study of high-spin states and magnetic scattering constitute the main goals of the electron scattering program at Bates. Representative results are presented; completed work is reported in the usual publications. (RWR)

  4. Management of aging of nuclear power plant containment structures

    SciTech Connect

    Naus, D.; Oland, C.B.; Ellingwood, B.; Norris, W.E.; Graves, H.L. III

    1998-06-01

    Research addressing aging management of nuclear power plant concrete and steel containment structures is summarized. Accomplishments related to concrete containment structures include formation of a materials` property database; an aging assessment methodology to identify critical structures and degradation factors; guidelines and evaluation criteria for use in condition assessments; and a time-dependent reliability-based methodology for condition assessments and estimations of future performance. Under the steel containments and liners activity, a degradation assessment methodology has been developed, mathematical models that describe time-dependent changes in the containment due to aggressive environmental factors have been identified, and statistical data supporting the use of these models in time-dependent reliability analysis have been summarized.

  5. Recent results on nuclear structure functions for light nuclei

    SciTech Connect

    Kulagin, S. A.; Petti, R.

    2011-09-21

    We discuss the nuclear EMC effect with particular emphasis on recent data for light nuclei including {sup 2}H, {sup 3}He, {sup 4}He, {sup 9}Be, {sup 12}C and {sup 14}N. In order to verify the consistency of available data, we calculate the {chi}{sup 2} deviation between different data sets. We find a good agreement between the results from the NMC, SLAC E139, and HERMES experiments. However, our analysis indicates an overall normalization offset of about 2% in the data from the recent JLab E03-103 experiment with respect to previous data for nuclei heavier than {sup 3}He. We also discuss the extraction of the neutron/proton structure function ratio F{sub 2}{sup n}/F{sub 2}{sup p} from the nuclear ratios {sup 3}He/{sup 2}H and {sup 2}H/{sup 1}H. Our analysis shows that the E03-103 data on {sup 3}He/{sup 2}H require a renormalization of about 3% in order to be consistent with the F{sub 2}{sup n}/F{sub 2}{sup p} ratio obtained from the NMC experiment. After such a renormalization, the {sup 3}He data from the E03-103 data and HERMES experiments are in a good agreement. We also present a detailed comparison between data and model calculations, which include a description of the nuclear binding, Fermi motion and off-shell corrections to the structure functions of bound proton and neutron, as well as the nuclear pion and shadowing corrections.

  6. The solution conformation of the antibacterial peptide cecropin A: A nuclear magnetic resonance and dynamical simulated annealing study

    SciTech Connect

    Holak, T.A.; Gronenborn, A.M.; Clore, G.M. ); Engstroem, A.; Kraulis, P.J.; Lindeberg, G.; Bennich, H.; Jones, T.A. )

    1988-10-04

    The solution conformation of the antibacterial polypeptide cecropin A from the Cecropia moth is investigated by nuclear magnetic resonance (NMR) spectroscopy under conditions where it adopts a fully ordered structure, as judged by previous circular dichroism studies. By use of a combination of two-dimensional NMR techniques the {sup 1}H NMR spectrum of cecropin A is completely assigned. A set of 243 approximate interproton distance restraints is derived from nuclear Overhauser enhancement (NOE) measurements. These, together with 32 restraints for the 16 intrahelical hydrogen bonds identified on the basis of the pattern of short-range NOEs, form the basis of a three-dimensional structure determination by dynamical simulated annealing. The calculations are carried out starting from three initial structures, an {alpha}-helix, an extended {beta}-strand, and a mixed {alpha}/{beta} structure. Seven independent structures are computed from each starting structure by using a different random number seeds for the assignments of the initial velocities. Analysis of the 21 converged structure indicates that there are two helical regions extending from residues 5 to 21 and from residues 24 to 37 which are very well defined in terms of both atomic root mean square differences and backbone torsion angles. The long axes of the two helices lie in two planes, which are at an angle of 70-100{degree} to each other. The orientation of the helices within these planes, however, cannot be determined due to the paucity of NOEs between the two helices.

  7. OVERVIEW OF A RECONFIGURABLE SIMULATOR FOR MAIN CONTROL ROOM UPGRADES IN NUCLEAR POWER PLANTS

    SciTech Connect

    Ronald L. Boring

    2012-10-01

    This paper provides background on a reconfigurable control room simulator for nuclear power plants. The main control rooms in current nuclear power plants feature analog technology that is growing obsolete. The need to upgrade control rooms serves the practical need of maintainability as well as the opportunity to implement newer digital technologies with added functionality. There currently exists no dedicated research simulator for use in human factors design and evaluation activities for nuclear power plant modernization in the U.S. The new research simulator discussed in this paper provides a test bed in which operator performance on new control room concepts can be benchmarked against existing control rooms and in which new technologies can be validated for safety and usability prior to deployment.

  8. Structure of overheated metal clusters: MD simulation study

    SciTech Connect

    Vorontsov, Alexander

    2015-08-17

    The structure of overheated metal clusters appeared in condensation process was studied by computer simulation techniques. It was found that clusters with size larger than several tens of atoms have three layers: core part, intermediate dense packing layer and a gas- like shell with low density. The change of the size and structure of these layers with the variation of internal energy and the size of cluster is discussed.

  9. Numerical simulations of drop impact on superhydrophobic structured surfaces

    NASA Astrophysics Data System (ADS)

    Guzzetti, Davide; Larentis, Stefano; Pugno, Nicola

    2011-11-01

    During the last decade drop impact dynamics on superhydrophobic surfaces has been intensively investigated because of the incredible properties of water repellency exhibited by this kind of surfaces, mostly inspired by biological examples such as Lotus leave. Thanks to the recent progress in micro-fabrication technology is possible to tailor surfaces wettability defining specific pillar-like structured surfaces. In this work, the behavior of impinging drops on these pillar-like surfaces is simulated, characterizing temporal evolution of droplets contact radius and drop maximal deformation dependence on Weber number. Numerical simulations results are compared with theoretical and experimental results guaranteeing simulation reliability. Fingering patterns obtained from drop impact has been studied obtaining a correlation between number of fingers and Weber number. Drop fragmentation pattern obtained from simulations supports the proposed correlation. Different drop impact outcomes (e.g. rebound, fragmentation) on structured superhydrophobic surfaces are simulated, focusing on the influence of micro-structured surface geometrical pattern. This investigation is relevant in order to define design rules for possible reliable non wettable surfaces. Financial support by Alta Scuola Politecnica.

  10. Multiscale Simulations of the Structure and Dynamics of the Magnetopause

    NASA Astrophysics Data System (ADS)

    Berchem, Jean; Lapenta, Giovanni; Ashour-Abdalla, Maha

    2016-04-01

    Ongoing observations by the spacecraft of NASA's Magnetospheric Multiscale Mission are revealing a very complex structure and dynamics of the low-latitude magnetopause. One of the main difficulties to comprehend physical processes occurring at the magnetopause is that it requires following both the evolution of the large-scale interaction of the solar wind with the dayside magnetosphere, and the details of the kinetic processes that enable transport of energy and mass in localized regions of the magnetospheric boundary. To address this multiscale problem, we have carried out particle-in-cell (PIC) simulations of the dayside magnetopause. These simulations employ domains that are large enough to include large-scale features of the solar wind interaction with the geomagnetic field (e.g., field curvature and plasma asymmetries). The numerical challenge is dealt with by using the implicit iPic3d simulation code together with the results of global magnetohydrodynamic (MHD) simulations. We discuss the results of the PIC simulations in the context of the global MHD states that provide initial and boundary conditions, and local spacecraft observations at the magnetopause. In particular, we analyze the evolution of electromagnetic fields and particle distributions in different regions of the simulations to determine how reconnection processes affect the structure and dynamics of the magnetospheric boundary.

  11. Challenges in structural analysis for deformed nuclear reactivity assessments.

    SciTech Connect

    Tallman, Tyler N.; Smith, Jeffrey A.; Villa, Daniel L.

    2010-09-01

    Launch safety calculations for past space reactor concepts have usually been limited to immersion of the reactor in water and/or sand, using nominal system geometries or in some cases simplified compaction scenarios. Deformation of the reactor core by impact during the accident sequence typically has not been considered because of the complexity of the calculation. Recent advances in codes and computing power have made such calculations feasible. The accuracy of such calculations depends primarily on the underlying structural analysis. Even though explicit structural dynamics is a mature field, nuclear reactors present significant challenges to obtain accurate deformation predictions. The presence of a working fluid is one of the primary contributors to challenges in these predictions. The fluid-structure interaction cannot be neglected because the fluid surrounds the nuclear fuel which is the most important region in the analysis. A detailed model of a small eighty-five pin reactor was built with the working fluid modeled as smoothed particle hydrodynamic (SPH) elements. Filling the complex volume covered by the working fluid with SPH elements required development of an algorithm which eliminates overlaps between hexahedral and SPH elements. The results with and without the working fluid were found to be considerably different with respect to reactivity predictions.

  12. Linking Nuclear Reactions and Nuclear Structure on the Way to the Drip Line

    NASA Astrophysics Data System (ADS)

    Dickhoff, Willem

    2012-10-01

    The present understanding of the role of short- and long-range physics in determining proton properties near the Fermi energy for stable closed-shell nuclei has relied on data from the (e,e'p) reaction. Hadronic tools to extract such spectroscopic information have been hampered by the lack of a consistent reaction description that provides unambiguous and undisputed results. The dispersive optical model (DOM), originally conceived by Claude Mahaux, provides a unified description of both elastic nucleon scattering and structure information related to single-particle properties below the Fermi energy. The DOM provides the starting point to provide a framework in which nuclear reactions and structure data can be analyzed consistently to provide unambiguous spectroscopic information including its asymmetry dependence. Recent extensions of this approach include the treatment of non-locality to describe experimental data like the nuclear charge density based on information of the spectral density below the Fermi energy, the application of the DOM ingredients to the description of transfer reactions, a comparison of the microscopic content of the nucleon self-energy based on Faddeev-RPA calculations emphasizing long-range correlations with DOM potentials, and a study of the relation between a self-energy which includes the effect of short-range correlations with DOM potentials. The most recent Dom implementation currently in progress abandons the constraint of local potentials completely to allow an accurate description of various properties of the nuclear ground state.

  13. CAD-based Monte Carlo Program for Integrated Simulation of Nuclear System SuperMC

    NASA Astrophysics Data System (ADS)

    Wu, Yican; Song, Jing; Zheng, Huaqing; Sun, Guangyao; Hao, Lijuan; Long, Pengcheng; Hu, Liqin

    2014-06-01

    Monte Carlo (MC) method has distinct advantages to simulate complicated nuclear systems and is envisioned as routine method for nuclear design and analysis in the future. High fidelity simulation with MC method coupled with multi-physical phenomenon simulation has significant impact on safety, economy and sustainability of nuclear systems. However, great challenges to current MC methods and codes prevent its application in real engineering project. SuperMC is a CAD-based Monte Carlo program for integrated simulation of nuclear system developed by FDS Team, China, making use of hybrid MC-deterministic method and advanced computer technologies. The design aim, architecture and main methodology of SuperMC were presented in this paper. SuperMC2.1, the latest version for neutron, photon and coupled neutron and photon transport calculation, has been developed and validated by using a series of benchmarking cases such as the fusion reactor ITER model and the fast reactor BN-600 model. SuperMC is still in its evolution process toward a general and routine tool for nuclear system. Warning, no authors found for 2014snam.conf06023.

  14. Global MHD Simulation of Mesoscale Structures at the Magnetospheric Boundary

    NASA Technical Reports Server (NTRS)

    Berchem, Jean

    1998-01-01

    The research carried out for this protocol was focused on the study of mesoscales structures at the magnetospheric boundary. We investigated three areas: (1) the structure of the magnetospheric boundary for steady solar wind conditions; (2) the dynamics of the dayside magnetospheric boundary and (3) the dynamics of the distant tail magnetospheric boundary. Our approach was to use high resolution three-dimensional global magnetohydrodynamic (MHD) simulations of the interaction of the solar wind with the Earth's magnetosphere. We first considered simple variations of the interplanetary conditions to obtain generic cases that helped us in establishing the basic cause and effect relationships for steady solar wind conditions. Subsequently, we used actual solar wind plasma and magnetic field parameters measured by an upstream spacecraft as input to the simulations and compared the simulation results with sequences of events observed by another or several other spacecraft located downstream the bow shock. In particular we compared results with observations made when spacecraft crossed the magnetospheric boundary.

  15. Geant4-Simulations for cellular dosimetry in nuclear medicine.

    PubMed

    Freudenberg, Robert; Wendisch, Maria; Kotzerke, Jörg

    2011-12-01

    The application of unsealed radionuclides in radiobiological experiments can lead to intracellular radionuclide uptake and an increased absorbed dose. Accurate dose quantification is essential to assess observed radiobiological effects. Due to small cellular dimensions direct dose measurement is impossible. We will demonstrate the application of Monte Carlo simulations for dose calculation. Dose calculations were performed using the Geant4 Monte Carlo toolkit, wherefore typical experimental situations were designed. Dose distributions inside wells were simulated for different radionuclides. S values were simulated for spherical cells and cell monolayers of different diameter. Concomitantly experiments were performed using the PC Cl3 cell line with mediated radionuclide uptake. For various activity distributions cellular survival was measured. We yielded S values for dose distribution inside the wells. Calculated S values for a single cell are in good agreement to S values provided in the literature (ratio 0.87 to 1.07). Cross-dose is up to ten times higher for Y-90. Concomitantly performed cellular experiments confirm the dose calculation. Furthermore the necessity of correct dose calculation was shown for assessment of radiobiological effects after application of unsealed radionuclides. Thereby the feasibility of using Geant4 was demonstrated. PMID:21983023

  16. Hybrid Simulation of Linked Structural System With Shear Friction Damper

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-soo; Choi, Jae-hyouk

    2011-01-01

    Hybrid simulations were conducted to investigate effects of the friction damper on seismic behavior of a composite structure consisting of an old concrete structure and a new steel frame. The hybrid simulation results have indicated that the cyclical behavior of the friction damper made of steel plate and aluminum plate could be accurately simulated with the so-called perfect elastic-plastic model without degradation in stiffness. It has also been verified that the seismic performance of the composite structures could be accurately predicted if one use the perfect elastic-plastic model to simulate the behavior of the connecting friction damper. In addition, the tests have shown that the use of friction damper to connect an existing unfit concrete building and new steel building could effectively reduce their displacement response and acceleration response simultaneously. The mitigation degree due to the friction damper on the seismic response of the composite structures depends upon the relative stiffness of the two buildings, the natural periods, and the mass ratio of the two buildings.

  17. Structural materials from lunar simulants through thermal liquefaction

    NASA Technical Reports Server (NTRS)

    Desai, Chandra S.; Girdner, Kirsten

    1992-01-01

    Thermal liquefaction that allows development of intermediate ceramic composites from a lunar simulant with various admixtures is used to develop structural materials for construction on the moon. Bending and compressive properties of resulting composites are obtained from laboratory tests and evaluated with respect to the use of three different types and fibers.

  18. Methodology for reliability based condition assessment. Application to concrete structures in nuclear plants

    SciTech Connect

    Mori, Y.; Ellingwood, B.

    1993-08-01

    Structures in nuclear power plants may be exposed to aggressive environmental effects that cause their strength to decrease over an extended period of service. A major concern in evaluating the continued service for such structures is to ensure that in their current condition they are able to withstand future extreme load events during the intended service life with a level of reliability sufficient for public safety. This report describes a methodology to facilitate quantitative assessments of current and future structural reliability and performance of structures in nuclear power plants. This methodology takes into account the nature of past and future loads, and randomness in strength and in degradation resulting from environmental factors. An adaptive Monte Carlo simulation procedure is used to evaluate time-dependent system reliability. The time-dependent reliability is sensitive to the time-varying load characteristics and to the choice of initial strength and strength degradation models but not to correlation in component strengths within a system. Inspection/maintenance strategies are identified that minimize the expected future costs of keeping the failure probability of a structure at or below an established target failure probability during its anticipated service period.

  19. Nuclear reactor containment structure with continuous ring tunnel at grade

    DOEpatents

    Seidensticker, Ralph W.; Knawa, Robert L.; Cerutti, Bernard C.; Snyder, Charles R.; Husen, William C.; Coyer, Robert G.

    1977-01-01

    A nuclear reactor containment structure which includes a reinforced concrete shell, a hemispherical top dome, a steel liner, and a reinforced-concrete base slab supporting the concrete shell is constructed with a substantial proportion thereof below grade in an excavation made in solid rock with the concrete poured in contact with the rock and also includes a continuous, hollow, reinforced-concrete ring tunnel surrounding the concrete shell with its top at grade level, with one wall integral with the reinforced concrete shell, and with at least the base of the ring tunnel poured in contact with the rock.

  20. Formal Nuclear and Atomic Structure of the Elements

    NASA Astrophysics Data System (ADS)

    Nduka, Amagh

    2004-05-01

    In the paper "The Space of 4-Operators and the Unification of the Fundamental Interactions" (see APS paper with log number 10016) we discussed the Fundamental Particle Scheme (not the Standard Model). As an application of the theory, we discuss in this paper formal atomic and nuclear structures and (1) deduce the correct periodic table of the elements that accounts for the missing elements of the empirically derived Chancourtois-Newlands-Lothar Meyer-Mendeleev table; and a table of the nuclides, (2) calculate the mass of the electron neutrino, and deduce the missing mass and dark matter of the universe.

  1. Disentangling Effects of Nuclear Structure in Heavy Element Formation

    SciTech Connect

    Hinde, D. J.; Thomas, R. G.; Rietz, R. du; Diaz-Torres, A.; Dasgupta, M.; Brown, M. L.; Evers, M.; Gasques, L. R.; Rafiei, R.; Rodriguez, M. D.

    2008-05-23

    Forming the same heavy compound nucleus with different isotopes of the projectile and target elements allows nuclear structure effects in the entrance channel (resulting in static deformation) and in the dinuclear system to be disentangled. Using three isotopes of Ti and W, forming {sup 232}Cm, with measurement spanning the capture barrier energies, alignment of the heavy prolate deformed nucleus is shown to be the main reason for the broadening of the mass distribution of the quasifission fragments as the beam energy is reduced. The complex, consistently evolving mass-angle correlations that are observed carry more information than the integrated mass or angular distributions, and should severely test models of quasifission.

  2. Impact of nuclear structure on production of superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Adamian, G. G.; Antonenko, N. V.; Bezbakh, A. N.; Shneidman, T. M.; Scheid, W.

    2014-05-01

    The calculations performed with the modified two-center shell model reveal quite strong shell effects at Z = 120 - 126 and N = 184 as in the self-consistent mean-field treatments. If our prediction of the structure of heaviest nuclei is correct, than one can expect the production of evaporation residues Z = 120 in the reactions50Ti+249Cf and 54Cr+248Cm in near future. The nuclear level densities were calculated for the nuclei of a-decay chains containing 296,298,300120. The minima of the level density parameter clearly indicate the strong shell effect at Z = 120.

  3. Simulating the large-scale structure of HI intensity maps

    NASA Astrophysics Data System (ADS)

    Seehars, Sebastian; Paranjape, Aseem; Witzemann, Amadeus; Refregier, Alexandre; Amara, Adam; Akeret, Joel

    2016-03-01

    Intensity mapping of neutral hydrogen (HI) is a promising observational probe of cosmology and large-scale structure. We present wide field simulations of HI intensity maps based on N-body simulations of a 2.6 Gpc / h box with 20483 particles (particle mass 1.6 × 1011 Msolar / h). Using a conditional mass function to populate the simulated dark matter density field with halos below the mass resolution of the simulation (108 Msolar / h < Mhalo < 1013 Msolar / h), we assign HI to those halos according to a phenomenological halo to HI mass relation. The simulations span a redshift range of 0.35 lesssim z lesssim 0.9 in redshift bins of width Δ z ≈ 0.05 and cover a quarter of the sky at an angular resolution of about 7'. We use the simulated intensity maps to study the impact of non-linear effects and redshift space distortions on the angular clustering of HI. Focusing on the autocorrelations of the maps, we apply and compare several estimators for the angular power spectrum and its covariance. We verify that these estimators agree with analytic predictions on large scales and study the validity of approximations based on Gaussian random fields, particularly in the context of the covariance. We discuss how our results and the simulated maps can be useful for planning and interpreting future HI intensity mapping surveys.

  4. Two-Phase flow instrumentation for nuclear accidents simulation

    NASA Astrophysics Data System (ADS)

    Monni, G.; De Salve, M.; Panella, B.

    2014-11-01

    The paper presents the research work performed at the Energy Department of the Politecnico di Torino, concerning the development of two-phase flow instrumentation and of models, based on the analysis of experimental data, that are able to interpret the measurement signals. The study has been performed with particular reference to the design of power plants, such as nuclear water reactors, where the two-phase flow thermal fluid dynamics must be accurately modeled and predicted. In two-phase flow typically a set of different measurement instruments (Spool Piece - SP) must be installed in order to evaluate the mass flow rate of the phases in a large range of flow conditions (flow patterns, pressures and temperatures); moreover, an interpretative model of the SP need to be developed and experimentally verified. The investigated meters are: Turbine, Venturi, Impedance Probes, Concave sensors, Wire mesh sensor, Electrical Capacitance Probe. Different instrument combinations have been tested, and the performance of each one has been analyzed.

  5. Global nuclear structure effects of the tensor interaction

    SciTech Connect

    Zalewski, M.; Olbratowski, P.; Rafalski, M.; Werner, T. R.; Satula, W.; Wyss, R. A.

    2009-12-15

    A direct fit of the isoscalar spin-orbit (SO) and both isoscalar and isovector tensor coupling constants to the f{sub 5/2}-f{sub 7/2} SO splittings in {sup 40}Ca, {sup 56}Ni, and {sup 48}Ca nuclei requires a drastic reduction of the isoscalar SO strength and strong attractive tensor coupling constants. The aim of this work is to address further consequences of these strong attractive tensor and weak SO fields on binding energies, nuclear deformability, and high-spin states. In particular, the contribution to the nuclear binding energy from the tensor field shows a generic magic structure with tensorial magic numbers N(Z)=14,32,56, or 90, corresponding to the maximum spin asymmetries in 1d{sub 5/2}, 1f{sub 7/2}+2p{sub 3/2}, 1g{sub 9/2}+2d{sub 5/2}, and 1h{sub 11/2}+2f{sub 7/2} single-particle configurations, respectively, and that these numbers are smeared out by pairing correlations and deformation effects. The consequences of strong attractive tensor fields and weak SO interaction for nuclear stability at the drip lines are also examined, particularly those close to the tensorial doubly magic nuclei. The possibility of an entirely new tensor-force-driven deformation effect is discussed.

  6. Apros-based Kola 1 nuclear power plant compact training simulator

    SciTech Connect

    Porkholm, K.; Kontio, H.; Nurmilaukas, P.

    1996-11-01

    Imatran Voima Oy`s subsidiary IVO International Ltd (IVO IN) and the Technical Research Centre of Finland (VTT) in co-operation with Kola staff supplies the Kola Nuclear Power Plant in the Murmansk region of Russia with a Compact Training Simulator. The simulator will be used for the training of the plant personnel in managing the plant disturbance and accident situations. By means of the simulator is is also possible to test how the planned plant modifications will affect the plant operation. The simulator delivery is financed by the Finnish Ministry of Trade and Industry and the Ministry of Foreign Affairs. The delivery is part of the aid program directed to Russia for the improvement of the nuclear power plant safety.

  7. Microwave Processing of Simulated Advanced Nuclear Fuel Pellets

    SciTech Connect

    D.E. Clark; D.C. Folz

    2010-08-29

    Throughout the three-year project funded by the Department of Energy (DOE) and lead by Virginia Tech (VT), project tasks were modified by consensus to fit the changing needs of the DOE with respect to developing new inert matrix fuel processing techniques. The focus throughout the project was on the use of microwave energy to sinter fully stabilized zirconia pellets using microwave energy and to evaluate the effectiveness of techniques that were developed. Additionally, the research team was to propose fundamental concepts as to processing radioactive fuels based on the effectiveness of the microwave process in sintering the simulated matrix material.

  8. Simulation of period doubling of recurrent solar wind structures

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.; Burlaga, L. F.

    1990-01-01

    Based on satellite observations of a recurrent solar wind structure conducted in 1974, an MHD simulation model, and input functions generated from plasma and magnetic field data, the continuing evolution of the solar wind structure outside 5 AU is studied. The model uses the Rankine-Hugoniot relations to describe the jumps in flow properties across the shocks, and it treats shocks as surfaces of discontinuity with zero thickness. Two interaction processes (the collision and the merging of shocks) play important roles in restructuring the solar wind in the outer heliosphere. The simulation result shows that period doubling occurs between 5 and 10 AU. The recurrent solar wind appears to be a persistent new structure between 10 and 20 AU, and it consists of one merged interaction region per solar rotation.

  9. Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)

    SciTech Connect

    Kimberlyn C. Mousseau

    2011-10-01

    The Nuclear Energy Computational Fluid Dynamics Advanced Modeling and Simulation (NE-CAMS) system is being developed at the Idaho National Laboratory (INL) in collaboration with Bettis Laboratory, Sandia National Laboratory (SNL), Argonne National Laboratory (ANL), Utah State University (USU), and other interested parties with the objective of developing and implementing a comprehensive and readily accessible data and information management system for computational fluid dynamics (CFD) verification and validation (V&V) in support of nuclear energy systems design and safety analysis. The two key objectives of the NE-CAMS effort are to identify, collect, assess, store and maintain high resolution and high quality experimental data and related expert knowledge (metadata) for use in CFD V&V assessments specific to the nuclear energy field and to establish a working relationship with the U.S. Nuclear Regulatory Commission (NRC) to develop a CFD V&V database, including benchmark cases, that addresses and supports the associated NRC regulations and policies on the use of CFD analysis. In particular, the NE-CAMS system will support the Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program, which aims to develop and deploy advanced modeling and simulation methods and computational tools for reliable numerical simulation of nuclear reactor systems for design and safety analysis. Primary NE-CAMS Elements There are four primary elements of the NE-CAMS knowledge base designed to support computer modeling and simulation in the nuclear energy arena as listed below. Element 1. The database will contain experimental data that can be used for CFD validation that is relevant to nuclear reactor and plant processes, particularly those important to the nuclear industry and the NRC. Element 2. Qualification standards for data evaluation and classification will be incorporated and applied such that validation data sets will result in well

  10. A MULTIDIMENSIONAL AND MULTIPHYSICS APPROACH TO NUCLEAR FUEL BEHAVIOR SIMULATION

    SciTech Connect

    R. L. Williamson; J. D. Hales; S. R. Novascone; M. R. Tonks; D. R. Gaston; C. J. Permann; D. Andrs; R. C. Martineau

    2012-04-01

    Important aspects of fuel rod behavior, for example pellet-clad mechanical interaction (PCMI), fuel fracture, oxide formation, non-axisymmetric cooling, and response to fuel manufacturing defects, are inherently multidimensional in addition to being complicated multiphysics problems. Many current modeling tools are strictly 2D axisymmetric or even 1.5D. This paper outlines the capabilities of a new fuel modeling tool able to analyze either 2D axisymmetric or fully 3D models. These capabilities include temperature-dependent thermal conductivity of fuel; swelling and densification; fuel creep; pellet fracture; fission gas release; cladding creep; irradiation growth; and gap mechanics (contact and gap heat transfer). The need for multiphysics, multidimensional modeling is then demonstrated through a discussion of results for a set of example problems. The first, a 10-pellet rodlet, demonstrates the viability of the solution method employed. This example highlights the effect of our smeared cracking model and also shows the multidimensional nature of discrete fuel pellet modeling. The second example relies on our the multidimensional, multiphysics approach to analyze a missing pellet surface problem. As a final example, we show a lower-length-scale simulation coupled to a continuum-scale simulation.

  11. Reduced-Order Simulation of Large Accelerator Structures

    NASA Astrophysics Data System (ADS)

    Cooke, Simon

    2007-11-01

    Simulating electromagnetic waves inside finite periodic or almost periodic three-dimensional structures is important to research in linear particle acceleration, high power microwave generation, and photonic bandgap structures. While eigenmodes of periodic structures can be determined from analysis of a single unit cell, based on Floquet theory, the general case of aperiodic structures, with defects or non-uniform properties, typically requires 3D electromagnetic simulation of the entire structure. When the structure is large and high accuracy is necessary this can require high-performance computing techniques to obtain even a few eigenmodes [1]. To confront this problem, we describe an efficient, field-based algorithm that can accurately determine the complete eigenmode spectrum for extended aperiodic structures, up to some chosen frequency limit. The new method combines domain decomposition with a non-traditional, dual eigenmode representation of the fields local to each cell of the structure. Two related boundary value eigenproblems are solved numerically in each cell, with (a) electrically shielded, and (b) magnetically shielded interfaces, to determine a combined set of basis fields. By using the dual solutions in our field representation we accurately represent both the electric and magnetic surface currents that mediate coupling at the interfaces between adjacent cells. The solution is uniformly convergent, so that typically only a few modes are used in each cell. We present results from 3D simulations that demonstrate the speed and low computational needs of the algorithm. [1] Z. Li, et al, Nucl. Instrum. Methods Phys. Res., Sect. A 558 (2006), 168-174.

  12. Gaseous Diffusion and Pore Structure in Nuclear Graphites.

    NASA Astrophysics Data System (ADS)

    Mays, Timothy John

    Available from UMI in association with The British Library. With the incentive of providing more information for oxidation and safety studies of graphite components in thermal nuclear reactors, a new method has been developed to determine the gas transport pore structure in nuclear graphites. It involves an analysis of the dependence on pressure of the isobaric, isothermal (room temperature) diffusivity ratios of components in a binary gas mixture flowing through annular graphite samples. A Wicke-Kallenbach apparatus was specially built to measure He-Ar diffusivity ratios at pressures below 100 Torr. The new apparatus incorporates capacitance manometers and servovalves for pressure measurement and control, hot wire meters for flow rate measurements, and a mass spectrometer for gas analysis. As pressure decreased, the diffusivity ratios were observed to decrease non-linearly, indicating that the mechanism of flow in the materials was in the transition region between molecular and Knudsen diffusion. A mathematical model was derived to relate the pressure dependence of the transition diffusivity ratio to gas transport pore structure, and a statistical analysis based on Tikhonov regularisation was developed which gave a good fit of the model to the data, and optimal estimates of the number of model capillary pores, and the distribution of pore sizes. In comparison, the established methods of molecular diffusion and permeation (flow of pure gases) only give mean data on the pore size distribution. Pore structure data from the new method accurately predicted CO_2-Ar molecular diffusivity ratios, but overestimated N_2 permeability coefficients, due, it was assumed, to differences between diffusion and permeation pore structure. The cumulative volume distributions for transport pores from the transition diffusion data were similar in shape to those for open pores from mercury porosimetry, but shifted towards higher pore radii, indicating that diffusion is not so influenced

  13. Chlorine Nuclear Quadrupole Hyperfine Structure in the Vinyl - Chloride Complex

    NASA Astrophysics Data System (ADS)

    Leung, Helen O.; Marshall, Mark D.; Messinger, Joseph P.

    2015-06-01

    The microwave spectrum of the vinyl chloride--hydrogen chloride complex, presented at last year's symposium, is greatly complicated by the presence of two chlorine nuclei as well as an observed, but not fully explained tunneling motion. Indeed, although it was possible at that time to demonstrate conclusively that the complex is nonplanar, the chlorine nuclear quadrupole hyperfine splitting in the rotational spectrum resisted analysis. With higher resolution, Balle-Flygare Fourier transform microwave spectra, the hyperfine structure has been more fully resolved, but appears to be perturbed for some rotational transitions. It appears that knowledge of the quadrupole coupling constants will provide essential information regarding the structure of the complex, specifically the location of the hydrogen atom in HCl. Our progress towards obtaining values for these constants will be presented.

  14. Analysis of fine structure in the nuclear continuum

    SciTech Connect

    Shevchenko, A.; Kalmykov, Y.; Neumann-Cosel, P. von; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Carter, J.; Usman, I.; Cooper, G. R. J.; Fearick, R. W.

    2008-02-15

    Fine structure has been shown to be a general phenomenon of nuclear giant resonances of different multipolarities over a wide mass range. In this article we assess various techniques that have been proposed to extract quantitative information from the fine structure in terms of characteristic scales. These include the so-called local scaling dimension, the entropy index method, Fourier analysis, and continuous and discrete wavelet transforms. As an example, results on the isoscalar giant quadrupole resonance in {sup 208}Pb from high-energy-resolution inelastic proton scattering and calculations with the quasiparticle-phonon model are analyzed. Wavelet analysis, both continuous and discrete, of the spectra is shown to be a powerful tool to extract the magnitude and localization of characteristic scales.

  15. ROR nuclear receptors: structures, related diseases, and drug discovery

    PubMed Central

    Zhang, Yan; Luo, Xiao-yu; Wu, Dong-hai; Xu, Yong

    2015-01-01

    Nuclear receptors (NRs) are ligand-regulated transcription factors that regulate metabolism, development and immunity. The NR superfamily is one of the major classes of drug targets for human diseases. Retinoic acid receptor-related orphan receptor (ROR) α, β and γ belong to the NR superfamily, and these receptors are still considered as 'orphan' receptors because the identification of their endogenous ligands has been controversial. Recent studies have demonstrated that these receptors are regulated by synthetic ligands, thus emerge as important drug targets for the treatment of multiple sclerosis, rheumatoid arthritis, psoriasis, etc. Studying the structural basis and ligand development of RORs will pave the way for a better understanding of the roles of these receptors in human diseases. Here, we review the structural basis, disease relevance, strategies for ligand identification, and current status of development of therapeutic ligands for RORs. PMID:25500868

  16. Structures and construction of nuclear power plants on lunar surface

    NASA Astrophysics Data System (ADS)

    Shimizu, Katsunori; Kobatake, Masuhiko; Ogawa, Sachio; Kanamori, Hiroshi; Okada, Yasuhiko; Mano, Hideyuki; Takagi, Kenji

    1991-07-01

    The best structure and construction techniques of nuclear power plants in the severe environments on the lunar surface are studied. Facility construction types (functional conditions such as stable structure, shield thickness, maintainability, safety distances, and service life), construction conditions (such as construction methods, construction equipment, number of personnel, time required for construction, external power supply, and required transportation) and construction feasibility (construction method, reactor transportation between the moon and the earth, ground excavation for installation, loading and unloading, transportation, and installation, filling up the ground, electric power supply of plant S (300 kW class) and plant L (3000 kW class)) are outlined. Items to pay attention to in construction are (1) automation and robotization of construction; (2) cost reduction by multi functional robots; and (3) methods of supplying power to robots. A precast concrete block manufacturing plant is also outlined.

  17. Nuclear Structure Studies at the Future FAIR facility

    SciTech Connect

    Rubio, Berta

    2010-04-26

    This article is intended to be an introduction to studies of nuclear structure at the future FAIR facility. It addresses interested readers not necessarily expert in the field. It outlines the physics aims and experiments to be carried out at FAIR in the field of nuclear structure and astrophysics. Starting with a brief description of what can be achieved in experiments with intense, high quality stable beams the article leads the reader to how beams of unstable radioactive nuclei will be produced and exploited at FAIR. The characteristics of the beams from the main separation device, the Super-FRS, are outlined and the limitations they impose on experiment are discussed. The various setups at the three experimental branches associated with the Super-FRS are described. The aims of the various experimental setups, how they complement each other and the physics they will address are all explained. The concept of the r-process of nucleosynthesis is outlined at the beginning and used as a running example of how useful it will be to be able to carry out experiments with beams of short-lived, exotic ions.

  18. Simulation of the photogrammetric appendage structural dynamics experiment

    NASA Technical Reports Server (NTRS)

    Pappa, Richard S.; Gilbert, Michael G.; Welch, Sharon S.

    1995-01-01

    The Photogrammetric Appendage Structural Dynamics Experiment (PASDE) uses six video cameras in the Space Shuttle cargo bay to measure vibration of the Russian Mir space station Kvant-ll solar array. It occurs on Shuttle/Mir docking mission STS-74 scheduled for launch in November 1995. The objective of PASDE is to demonstrate photogrammetric technology for measuring 'untargeted' spacecraft appendage structural dynamics. This paper discusses a pre-flight simulation test conducted in July 1995, focusing on the image processing aspects. The flight camera system recorded vibrations of a full-scale structural test article having grids of white lines on black background, similar in appearance to the Mir solar array. Using image correlation analysis, line intersections on the structure are tracked in the video recordings to resolutions of less than 0.1 pixel. Calibration and merging of multiple camera views generated 3-dimensional displacements from which structural modal parameters are then obtained.

  19. Photoassisted Biodegradation of Irradiated Organics in Simulated Nuclear Wastewater.

    PubMed

    Makgato, Stanford S; Nkhalambayausi-Chirwa, Evans M

    2015-05-01

    The extent of dehalogenation and degradation of toxic aromatic compounds in a nuclear wastewater was evaluated using a two-stage system consisting of a photolytic reactor followed by a biological reactor. Experiments were performed by varying the initial 4-chlorophenol (4-CP) concentration from 50 to 1000 mg/L. The UV pretreatment stage improved the overall efficiency of biodegradation of the recalcitrant compound by facilitating degradability in the biological stage. Removal efficiencies greater than 98% were achieved at 4-CP feed concentrations < 50 mg/L. Adding an H2O2 dose of 0.1 mg/L as an oxidant further improved biodegradation under optimum operating conditions for the entire system. Some known aromatic compound degraders such as Pseudomonas aeruginosa and Pseudomonas mendocina were detected in the consortium using the 16S rRNA genetic fingerprint technique. To the authors' knowledge, this is the first study on biodegradation of halogenated aromatic compounds that are copollutants of metallic radionuclides in radioactive wastewater. PMID:26460459

  20. Modeling of Large Avionic Structures in Electrical Network Simulations

    NASA Astrophysics Data System (ADS)

    Piche, A.; Perraud, R.; Lochot, C.

    2012-05-01

    The extensive introduction of carbon fiber reinforced plastics (CFRP) in conjunction with an increase of electrical systems in aircraft has led to new electromagnetic issues. This situation has reinforced the need for numerical simulation early in the design phase. In this context, we have proposed [1] a numerical methodology to deal with 3D CFRP avionic structures in time domain simulations at system level. This paper presents the last results on this subject and particularly the modeling of A350 fuselage in SABER computation containing the aircraft power distribution.

  1. Research of TREETOPS Structural Dynamics Controls Simulation Upgrade

    NASA Technical Reports Server (NTRS)

    Yates, Rose M.

    1996-01-01

    Under the provisions of contract number NAS8-40194, which was entitled 'TREETOPS Structural Dynamics and Controls Simulation System Upgrade', Oakwood College contracted to produce an upgrade to the existing TREETOPS suite of analysis tools. This suite includes the main simulation program, TREETOPS, two interactive preprocessors, TREESET and TREEFLX, an interactive post processor, TREEPLOT, and an adjunct program, TREESEL. A 'Software Design Document', which provides descriptions of the argument lists and internal variables for each subroutine in the TREETOPS suite, was established. Additionally, installation guides for both DOS and UNIX platforms were developed. Finally, updated User's Manuals, as well as a Theory Manual, were generated.

  2. Simulations of the formation of large-scale structure

    NASA Astrophysics Data System (ADS)

    White, S. D. M.

    Numerical studies related to the simulation of structure growth are examined. The linear development of fluctuations in the early universe is studied. The research of Aarseth, Gott, and Turner (1979) based on N-body integrators that obtained particle accelerations by direct summation of the forces due to other objects is discussed. Consideration is given to the 'pancake theory' of Zel'dovich (1970) for the evolution from adiabatic initial fluctuation, the neutrino-dominated universe models of White, Frenk, and Davis (1983), and the simulations of Davis et al. (1985).

  3. Fundamental Science-Based Simulation of Nuclear Waste Forms

    SciTech Connect

    Devanathan, Ramaswami; Gao, Fei; Sun, Xin; Khaleel, Mohammad A.

    2010-10-04

    This report presents a hierarchical multiscale modeling scheme based on two-way information exchange. To account for all essential phenomena in waste forms over geological time scales, the models have to span length scales from nanometer to kilometer and time scales from picoseconds to millenia. A single model cannot cover this wide range and a multi-scale approach that integrates a number of different at-scale models is called for. The approach outlined here involves integration of quantum mechanical calculations, classical molecular dynamics simulations, kinetic Monte Carlo and phase field methods at the mesoscale, and continuum models. The ultimate aim is to provide science-based input in the form of constitutive equations to integrated codes. The atomistic component of this scheme is demonstrated in the promising waste form xenotime. Density functional theory calculations have yielded valuable information about defect formation energies. This data can be used to develop interatomic potentials for molecular dynamics simulations of radiation damage. Potentials developed in the present work show a good match for the equilibrium lattice constants, elastic constants and thermal expansion of xenotime. In novel waste forms, such as xenotime, a considerable amount of data needed to validate the models is not available. Integration of multiscale modeling with experimental work is essential to generate missing data needed to validate the modeling scheme and the individual models. Density functional theory can also be used to fill knowledge gaps. Key challenges lie in the areas of uncertainty quantification, verification and validation, which must be performed at each level of the multiscale model and across scales. The approach used to exchange information between different levels must also be rigorously validated. The outlook for multiscale modeling of wasteforms is quite promising.

  4. Impact of structural aging on seismic risk assessment of reinforced concrete structures in nuclear power plants

    SciTech Connect

    Ellingwood, B.; Song, J.

    1996-03-01

    The Structural Aging Program is addressing the potential for degradation of concrete structural components and systems in nuclear power plants over time due to aging and aggressive environmental stressors. Structures are passive under normal operating conditions but play a key role in mitigating design-basis events, particularly those arising from external challenges such as earthquakes, extreme winds, fires and floods. Structures are plant-specific and unique, often are difficult to inspect, and are virtually impossible to replace. The importance of structural failures in accident mitigation is amplified because such failures may lead to common-cause failures of other components. Structural condition assessment and service life prediction must focus on a few critical components and systems within the plant. Components and systems that are dominant contributors to risk and that require particular attention can be identified through the mathematical formalism of a probabilistic risk assessment, or PRA. To illustrate, the role of structural degradation due to aging on plant risk is examined through the framework of a Level 1 seismic PRA of a nuclear power plant. Plausible mechanisms of structural degradation are found to increase the core damage probability by approximately a factor of two.

  5. Track structure of carbon ions: measurements and simulations.

    PubMed

    Conte, V; Colautti, P; Moro, D; Grosswendt, B

    2014-10-01

    The likelihood of radiation to produce clustered damages in irradiated biological tissue and the reparability of such damages are closely related to the stochastics of localised ionising interactions within small volumes of nanometre sizes, determined by the particle track structure. Track structure investigations in nanometre-sized volumes have been subject of research for several decades, mainly by means of Monte Carlo simulations. Today, the 'track-nanodosimeter', installed at the TANDEM-ALPI accelerator complex of LNL, is a measuring device able to count the electrons produced in a 20-nm equivalent sensitive site (De Nardo et al. A detector for track-nanodosimetry. Nucl. Instrum. Methods. Phys. Res. A 484: , 312-326 (2002)). It allows studying track structure properties both in the near neighbourhood of a primary particle trajectory and separately in the penumbra region. An extended study for different ionising particles of medical interest has been recently performed with the track-nanodosimeter (Conte et al. Track structure of light ions: experiments and simulations. New J. Phys. 14: , 093010, (2012)). Here, new experimental data and results of Monte Carlo simulations for 240- and 96-MeV (12)C-ions are presented and discussed. PMID:24249779

  6. Simulation of Aircraft Engine Blade-Out Structural Dynamics. Revised

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles; Carney, Kelly; Gallardo, Vicente

    2001-01-01

    A primary concern of aircraft structure designers is the accurate simulation of the blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to insure structural integrity during flight as well as to guarantee successful blade-out certification testing. The system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes such as MSC NASTRAN are typically used and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine's turbomachinery. The present study provides the equations of motion for rotordynamic response including the effect of spooldown speed and rotor unbalance and examines the effects of these terms on a cantilevered rotor. The effect of spooldown speed is found to be greater with increasing spooldown rate. The parametric term resulting from the mass unbalance has a more significant effect on the rotordynamic response than does the spooldown term. The parametric term affects both the peak amplitudes as well as the resonant frequencies of the rotor.

  7. Simulation of Aircraft Engine Blade-Out Structural Dynamics

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles; Carney, Kelly; Gallardo, Vicente

    2001-01-01

    A primary concern of aircraft structure designers is the accurate simulation of the blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to insure structural integrity during flight as well as to guarantee successful blade-out certification testing. The system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes such as MSC NASTRAN are typically used and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine's turbomachinery. The present study provides the equations of motion for rotordynamic response including the effect of spooldown speed and rotor unbalance and examines the effects of these terms on a cantilevered rotor. The effect of spooldown speed is found to be greater with increasing spooldown rate. The parametric term resulting from the mass unbalance has a more significant effect on the rotordynamic response than does the spooldown term. The parametric term affects both the peak amplitudes as well as the resonant frequencies of the rotor.

  8. Structure-Based Simulations Reveal Concerted Dynamics of GPCR Activation

    PubMed Central

    Leioatts, Nicholas; Suresh, Pooja; Romo, Tod D.; Grossfield, Alan

    2014-01-01

    G protein-coupled receptors (GPCRs) are a vital class of proteins that transduce biological signals across the cell membrane. However, their allosteric activation mechanism is not fully understood; crystal structures of active and inactive receptors have been reported, but the functional pathway between these two states remains elusive. Here, we employ structure-based (Gō-like) models to simulate activation of two GPCRs, rhodopsin and the β2 adrenergic receptor (β2AR). We used data-derived reaction coordinates that capture the activation mechanism for both proteins, showing that activation proceeds through quantitatively different paths in the two systems. Both reaction coordinates are determined from the dominant concerted motions in the simulations so the technique is broadly applicable. There were two surprising results. First, the main structural changes in the simulations were distributed throughout the transmembrane bundle, and not localized to the obvious areas of interest, such as the intracellular portion of helix 6. Second, the activation (and deactivation) paths were distinctly non-monotonic, populating states that were not simply interpolations between the inactive and active structures. These transitions also suggest a functional explanation for β2AR’s basal activity: it can proceed through a more broadly defined path during the observed transitions. PMID:24889093

  9. 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.

  10. Crystal structure of a nuclear actin ternary complex.

    PubMed

    Cao, Tingting; Sun, Lingfei; Jiang, Yuxiang; Huang, Shanjin; Wang, Jiawei; Chen, Zhucheng

    2016-08-01

    Actin polymerizes and forms filamentous structures (F-actin) in the cytoplasm of eukaryotic cells. It also exists in the nucleus and regulates various nucleic acid transactions, particularly through its incorporation into multiple chromatin-remodeling complexes. However, the specific structure of actin and the mechanisms that regulate its polymeric nature inside the nucleus remain unknown. Here, we report the crystal structure of nuclear actin (N-actin) complexed with actin-related protein 4 (Arp4) and the helicase-SANT-associated (HSA) domain of the chromatin remodeler Swr1. The inner face and barbed end of N-actin are sequestered by interactions with Arp4 and the HSA domain, respectively, which prevents N-actin from polymerization and binding to many actin regulators. The two major domains of N-actin are more twisted than those of globular actin (G-actin), and its nucleotide-binding pocket is occluded, freeing N-actin from binding to and regulation by ATP. These findings revealed the salient structural features of N-actin that distinguish it from its cytoplasmic counterpart and provide a rational basis for its functions and regulation inside the nucleus. PMID:27457955

  11. A simulated force generator with an adaptive command structure

    NASA Astrophysics Data System (ADS)

    Hanes, P. Jeff

    2006-05-01

    The Force Laydown Automated Generator (FLAG) is a script-driven behavior model that automatically creates military formations from the platoon level up to division level for use in simulations built on the FLAMES simulation framework. The script allows users to define formation command structure, command relationships, vehicle type and equipment, and behaviors. We have used it to automatically generate more than 3000 units in a single simulation. Currently, FLAG is used in the Air Force Research Laboratory Munitions Directorate (AFRL/MN) to assist their Comprehensive Analysis Process (CAP). It produces a reasonable threat laydown of red forces for testing their blue concept weapons. Our success in the application of FLAG leads us to believe that it offers an invaluable potential for use in training environments and other applications that need a large number of reactive, adaptive forces - red or blue.

  12. Three new renal simulators for use in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Dullius, Marcos; Fonseca, Mateus; Botelho, Marcelo; Cunha, Clêdison; Souza, Divanízia

    2014-03-01

    Renal scintigraphy is useful to provide both functional and anatomic information of renal flow of cortical functions and evaluation of pathological collecting system. The objective of this study was develop and evaluate the performance of three renal phantoms: Two anthropomorphic static and another dynamic. The static images of the anthropomorphic phantoms were used for comparison with static renal scintigraphy with 99mTc-DMSA in different concentrations. These static phantoms were manufactured in two ways: one was made of acrylic using as mold a human kidney preserved in formaldehyde and the second was built with ABS (acrylonitrile butadiene styrene) in a 3D printer. The dynamic renal phantom was constructed of acrylic to simulate renal dynamics in scintigraphy with 99mTc-DTPA. These phantoms were scanned with static and dynamic protocols and compared with clinical data. Using these phantoms it is possible to acquire similar renal images as in the clinical scintigraphy. Therefore, these new renal phantoms can be very effective for use in the quality control of renal scintigraphy, and image processing systems.

  13. Raman study of aluminum speciation in simulated alkaline nuclear waste.

    PubMed

    Johnston, Cliff T; Agnew, Stephen F; Schoonover, Jon R; Kenney, John W; Page, Bobbi; Osborn, Jill; Corbin, Rob

    2002-06-01

    The chemistry of concentrated sodium aluminate solutions stored in many of the large, underground storage tanks containing high-level waste (HLW) at the Hanford and Savannah River Nuclear Reservations is an area of recent research interest. Not only is the presence of aluminate in solution important for continued safe storage of these wastes, the nature of both solid and solution aluminum oxyhydroxides is important for waste pretreatment. Moreover, for many tanks that have leaked high aluminum waste in the past, little is known about the speciation of Al in the soil. In this study, Raman spectroscopy has been used to investigate the speciation of the aqueous species in the Al2O3-Na2O-H2O system over a wide range of solution compositions and hydration. A ternary phase diagram has been used to correlate the observed changes in the spectra with the composition of the solution and with dimerization of aluminate that occurs at elevated aluminate concentrations (>1.5 M). Dimerization is evidenced by growth of new Al-O stretching bands at 535 and 695 cm(-1) at the expense of the aluminate monomer band at 620 cm(-1). The spectrum of water was strongly influenced by the high concentrations of Na+ and OH- (>17 M). Upon increasing the concentration of NaOH in solution, the delta-(H-O-H) bending band of water (v2 mode) increased in frequency to 1663 cm(-1), indicating that the water contained in the concentrated caustic solution was more strongly hydrogen bonded at the higher base content. In addition, the sharp, well-resolved band at 3610 cm(-1), assigned to the v(O-H) of free OH-, increased in intensity with increasing NaOH. Analysis of the v(O-H) bands in the 3800-2600 cm(-1) region supported the overall increase in hydrogen bonding as evidenced by the increase in relative intensity of a strongly hydrated water band at 3118 cm(-1). Taking into consideration the activity of water, the molar concentrations of the monomeric and dimeric aluminate species were estimated using

  14. Total simulation of operator team behavior in emergencies at nuclear power plants.

    PubMed

    Takano, K; Sunaoshi, W; Suzuki, K

    2000-09-01

    In a large and complex system (i.e., a space aeronautics and nuclear power plant) it would be valuable to conduct operator training and support to demonstrate standard operators' behavior in coping with an anomaly caused by multiple malfunctions in which procedures would not have been stipulated previously. A system simulating operator team behavior including individual operator's cognitive behavior, his operations and physical behavior, and even verbal communication among team members, has been developed for a typical commercial nuclear power plant. This simulation model is not a scenario-based system but a complete knowledge-based system, based on the mental model that was envisaged by detailed analyses of experimental results obtained in the full-scope plant simulator. This mental model is composed of a set of knowledge bases and rules able to generate both diagnosis and prognosis depending on the observed situation even for multiple malfunctions. Simulation results of operator team behavior and plant dynamics were compared with corresponding experiments in several anomalies of multiple malfunctions. The comparison showed a reasonable agreement, so the simulation conditions were varied on cognitive task processing speed of individual operators, on team role sharing scheme, and on human machine interface (1st generation to 2nd generation control panel) to assess the sensitivity of this simulation model. Finally, it was shown that this simulation model has applications for the use of training standards and computer aided operator support systems. PMID:10993327

  15. Analysis of Special Nuclear Material (SNM) detection and interdiction using a collaborative constructive simulation environment

    NASA Astrophysics Data System (ADS)

    Hendrix, Lee A.; Calman, Jack; Fisher, Brian M.; Kay, Stephen W.; Lavelle, Christopher M.; Mayo, Robert M.; Miller, Bruce E.; Ruben, Katherine M.; West, Roger L.

    2012-05-01

    The acquisition of systems to locate and interdict Special Nuclear Material (SNM) is significantly enhanced when trade space analysis of and CONOPS development for various proposed sensor systems is performed using realistic operational scenarios in a synthetic simulation environment. To this end, the U. S. Defense Threat Reduction Agency (DTRA) has developed a collaborative constructive simulation environment hosted at the DTRA Center at Ft. Belvoir, VA. The simulation environment includes a suite of modeling and simulation (M&S) tools, scenario vignette representations, geographic information databases, and authoritative sensor system representations. Currently focused on modeling the detection and interdiction of in-transit SNM, the M&S tools include the Monte Carlo N-Particle (MCNP) simulation for detailed nuclear transport calculations and the JHU/APL enhanced Joint Semi-Automated Forces (JSAF) synthetic simulation environment and several associated High-Level Architecture (HLA) federate simulations for engagement-level vignette executions. This presentation will focus on the JHU/APL enhancements to JSAF which have enabled the execution of SNM detection vignettes. These enhancements include the addition of a user-configurable Radioactive Material (RM) module for representation of SNM objects, a user-configurable RM Detection Module to represent operational and notional gamma and neutron detectors, a Radiation Attenuation Module to calculate net emissions at the detector face in the dynamic JSAF environment, and an RM Stimulation Module to represent notional proton and photon beam systems in active interrogation scenarios.

  16. Geothermal reservoir simulation to enhance confidence in predictions for nuclear waste disposal

    SciTech Connect

    Kneafsey, Timothy J.; Pruess, Karsten; O'Sullivan, Michael J.; Bodvarsson, Gudmundur S.

    2002-06-15

    Numerical simulation of geothermal reservoirs is useful and necessary in understanding and evaluating reservoir structure and behavior, designing field development, and predicting performance. Models vary in complexity depending on processes considered, heterogeneity, data availability, and study objectives. They are evaluated using computer codes written and tested to study single and multiphase flow and transport under nonisothermal conditions. Many flow and heat transfer processes modeled in geothermal reservoirs are expected to occur in anthropogenic thermal (AT) systems created by geologic disposal of heat-generating nuclear waste. We examine and compare geothermal systems and the AT system expected at Yucca Mountain, Nevada, and their modeling. Time frames and spatial scales are similar in both systems, but increased precision is necessary for modeling the AT system, because flow through specific repository locations will affect long-term ability radionuclide retention. Geothermal modeling experience has generated a methodology, used in the AT modeling for Yucca Mountain, yielding good predictive results if sufficient reliable data are available and an experienced modeler is involved. Codes used in geothermal and AT modeling have been tested extensively and successfully on a variety of analytical and laboratory problems.

  17. Prototyping and validating requirements of radiation and nuclear emergency plan simulator

    SciTech Connect

    Hamid, AHA.; Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A.

    2015-04-29

    Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder’s intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties’ absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex.

  18. Prototyping and validating requirements of radiation and nuclear emergency plan simulator

    NASA Astrophysics Data System (ADS)

    Hamid, AHA.; Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A.

    2015-04-01

    Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder's intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties' absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex.

  19. Fluid Structure Interaction Simulations of Pediatric Ventricular Assist Device Operation

    NASA Astrophysics Data System (ADS)

    Long, Chris; Marsden, Alison; Bazilevs, Yuri

    2011-11-01

    Pediatric ventricular assist devices (PVADs) are used for mechanical circulatory support in children with failing hearts. They can be used to allow the heart to heal naturally or to extend the life of the patient until transplant. A PVAD has two chambers, blood and air, separated by a flexible membrane. The air chamber is pressurized, which drives the membrane and pumps the blood. The primary risk associated with these devices is stroke or embolism from thrombogenesis. Simulation of these devices is difficult due to a complex coupling of two fluid domains and a thin membrane, requiring fluid-structure interaction modeling. The goal of this work is to accurately simulate the hemodynamics of a PVAD. We perform FSI simulations using an Arbitrary Lagrangian-Eulerian (ALE) finite element framework to account for large motions of the membrane and the fluid domains. The air, blood, and membrane are meshed as distinct subdomains, and a method for non-matched discretizations at the fluid-structure interface is presented. The use of isogeometric analysis to model the membrane mechanics is also discussed, and the results of simulations are presented.

  20. Tracking Non-rigid Structures in Computer Simulations

    SciTech Connect

    Gezahegne, A; Kamath, C

    2008-01-10

    A key challenge in tracking moving objects is the correspondence problem, that is, the correct propagation of object labels from one time step to another. This is especially true when the objects are non-rigid structures, changing shape, and merging and splitting over time. In this work, we describe a general approach to tracking thousands of non-rigid structures in an image sequence. We show how we can minimize memory requirements and generate accurate results while working with only two frames of the sequence at a time. We demonstrate our results using data from computer simulations of a fluimix problem.

  1. Structure identification methods for atomistic simulations of crystalline materials

    DOE PAGESBeta

    Stukowski, Alexander

    2012-05-28

    Here, we discuss existing and new computational analysis techniques to classify local atomic arrangements in large-scale atomistic computer simulations of crystalline solids. This article includes a performance comparison of typical analysis algorithms such as common neighbor analysis (CNA), centrosymmetry analysis, bond angle analysis, bond order analysis and Voronoi analysis. In addition we propose a simple extension to the CNA method that makes it suitable for multi-phase systems. Finally, we introduce a new structure identification algorithm, the neighbor distance analysis, which is designed to identify atomic structure units in grain boundaries.

  2. Simulation of terahertz metamaterial absorbers with microbolometer structure

    NASA Astrophysics Data System (ADS)

    Ding, Jie; Wang, Jun; Guo, Xiaopei; Jiang, Yadong; Fan, Lin

    2014-09-01

    The metamaterial absorber in terahertz (THz) region, with the metal pattern layer/dielectric spacer/metal reflective layer sandwich structure, is characterized in this paper. The principle of metamaterial absorber absorbing terahertz wave was introduced firstly. The top layer of metamaterial absorber is a periodically patterned with metallic subwavelength structure, which also serves as an electric resonator. The bottom layer is a thick metal plane, which is used to reduce THz wave transmittance. The dielectric layer between two metallic layers results in magnetic resonance and the resonance depends on the thickness and dielectric constant of the dielectric layer. The absorption of metamaterial absorber to terahertz wave was simulated with CST software. The relationship between the size of the metamaterial structure and absorption frequency was analyzed with the simulation results. The results indicate that the absorption frequency is affected by the cell constant and geometric structure of top metal pattern, and absorption rate is related to both the thickness of dielectric layer and the size of resonator. In the end, the possibility of integrating the metamaterial absorber with micro-bridge structure to design room temperature terahertz detector was discussed, and the manufacturing process was introduced about room temperature terahertz detector with high THz wave absorption rate.

  3. Simulation of interdigitated back contact solar cell with trench structure

    NASA Astrophysics Data System (ADS)

    Kim, Soo Min; Chun, Seungju; Kang, Min Gu; Song, Hee-Eun; Lee, Jong-Han; Boo, Hyunpil; Bae, Soohyun; Kang, Yoonmook; Lee, Hae-Seok; Kim, Donghwan

    2015-02-01

    We performed two-dimensional technology computer-aided design simulations for interdigitated back contact (IBC) solar cells with rear trench structures (TS), denoted here as TS-IBC solar cells. First, we calculated a reference simulation model for conventional IBC solar cells. We then assumed a trench structure at the rear surface of the IBC solar cell. For this structure, we analyzed solar cell performance as a function of various trench depths and type. It was found that emitter trench formation affects minority carrier collection, such that the short-circuit current density increases with increasing trench depth. However, the back-surface field (BSF) trench exhibited poor minority carrier collection, which reduced the conversion efficiency of the TS-IBC solar cells. It was also found that for the same trench depth (30 μm), the difference in conversion efficiencies of an IBC solar cell with an emitter trench and that with a BSF trench was 0.6%. We are thus convinced that the emitter trench structure is more important than the BSF trench structure.

  4. Nuclear Technology Series. Course 29: Civil/Structural Inspection.

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This technical specialty course is one of thirty-five courses designed for use by two-year postsecondary institutions in five nuclear technician curriculum areas: (1) radiation protection technician, (2) nuclear instrumentation and control technician, (3) nuclear materials processing technician, (4) nuclear quality-assurance/quality-control…

  5. NPTool: a simulation and analysis framework for low-energy nuclear physics experiments

    NASA Astrophysics Data System (ADS)

    Matta, A.; Morfouace, P.; de Séréville, N.; Flavigny, F.; Labiche, M.; Shearman, R.

    2016-08-01

    The Nuclear Physics Tool (NPTool) is an open source data analysis and Monte Carlo simulation framework that has been developed for low-energy nuclear physics experiments with an emphasis on radioactive beam experiments. The NPTool offers a unified framework for designing, preparing and analyzing complex experiments employing multiple detectors, each of which may comprise some hundreds of channels. The framework has been successfully used for the analysis and simulation of experiments at facilities including GANIL, RIKEN, ALTO and TRIUMF, using both stable and radioactive beams. This paper details the NPTool philosophy together with an overview of the workflow. The framework has been benchmarked through the comparison of simulated and experimental data for a variety of detectors used in charged particle and gamma-ray spectroscopy.

  6. Artificial Market Simulation with Embedded Complex Network Structures

    NASA Astrophysics Data System (ADS)

    Uchida, Makoto; Shirayama, Susumu

    We investigate a factor of the `network effect' that affects on communication service markets by a multi-agent based simulation approach. The network effect is one of a market characteristic, whereby the benefit of a service or a product increase with use. So far, the network effect has been studied in terms of macroscopic metrics, and interaction patterns of consumers in the market were often ignored. To investigate an infulence of structures of the interaction patterns, we propose a multi-agent based model for a communication serivce market, in which embedded complex network structures are considered as an interaction pattern of agents. Using several complex network models as the interaction patterns, we study the dynamics of a market in which two providers are competing. By a series of simulations, we show that the structural properties of the complex networks, such as the clustering coefficient and degree correlations, are the major factors of the network effect. We also discuss an adequate model of the interaction pattern for reproducing the market dynamics in the real world by performing simulations exploiting with a real data of social network.

  7. Structure and Properties of HELICAL CARBON NANOTUBES through MD Simulations

    NASA Astrophysics Data System (ADS)

    Dahiya, Akshay; Verma, Deepti; Gupta, Shakti S.

    Helical Carbon Nanotubes (HCNTs) are coiled 3-valent carbon networks which represent pure carbon helix. Here we study the geometries of two classes: hexagonal helix containing purely polyhex networks and the second class with 5-and 7-membered rings besides hexagons. We followed a model of hexagonal, single wall HCNTs, and determined their relaxed configuration using MD simulations based on Tersoff potential. A race-track like structure is observed in the cross-section of HCNTs upon minimization. For generating class two helix, the adjacency matrix eigenvector's (AME) method is applied which utilizes 3-coordinated tiling of the plane by 5-,6-,and 7-membered ring for the construction of helical structures. The application of the AME method to torusenes is crucial for class two helix generation as it is based on an appropriate choice of bi-lobial eigenvectors triplet which can be selected on the basis of their nodal properties as verified here. After 3-D transformations the final structure was obtained with the help of MM3-potential based MD simulations on Tinker commercial code. The spring constants of HCNTs are computed through MD simulations.

  8. Coupled Eulerian/Lagrangian Simulation for Overpressure Structural Response

    NASA Astrophysics Data System (ADS)

    Lloyd, Andrew; Pan, Hua; Miller, David; Cogar, John

    2011-06-01

    Accurately modeling blast dynamics is critical in the assessment of structures subjected to blast loading. The current industry standard for modeling blast effects in Lagrangian based Finite Element simulations is CONWEP; tabulated pressure data taken directly from blast events. CONWEP is limited, however, and may not always be physically representative of the blast/structural interaction that occurs in the field. Eulerian hydrocodes provide advantages over CONWEP in that they can capture shock front interaction and model blast surface interfaces with fidelity due to the presence of the working fluid. Eulerian codes, however, break down over larger time scales; whereas, Lagrangian modeling allows for discrete finite elements with definable boundary interfaces that can be tracked out to longer time scales. Hence, a hybrid approach that couples the Eulerian blast modeling with Lagrangian system dynamics is necessary. The objective of this paper is to demonstrate improvements in overpressure structural response modeling using a Coupled Eulerian/Lagrangian algorithm implemented in VelodyneTM. Velodyne results using the Coupled Eulerian/Lagrangian algorithm are compared to results from Eulerian hydrocode simulations and Velodyne simulations using the CONWEP algorithm.

  9. Coupled Euler-La Grange simulation for overpressure structural response

    NASA Astrophysics Data System (ADS)

    Lloyd, Andrew N.; Miller, David K.; Pan, Hua; Cogar, John

    2012-03-01

    Accurately modeling blast dynamics is critical in the assessment of structures subjected to blast loading. The current industry standard for modeling blast effects in La Grange based finite element simulations is CONWEP; tabulated pressure data taken directly from blast events. CONWEP is limited, however, and may not always be physically representative of the blast/structural interaction that occurs in the field. Euler hydrocodes provide advantages over CONWEP in that they can capture shock front interaction and model blast surface interfaces with fidelity due to the presence of the working fluid. Euler codes, however, break down over larger time scales due to advection; whereas, Lagrange modeling allows for discrete finite elements with definable boundary interfaces that can be tracked out to longer time scales. Hence, a hybrid approach that couples the Euler blast modeling with La Grange system dynamics is necessary. The objective of this paper is to demonstrate improvements for high explosive overpressure structural response modeling specifically with respect COMP-B high explosive acting upon blasted fragments using a Coupled Euler-La Grange algorithm implemented in VelodyneTM. Velodyne results using the Coupled Euler-La Grange algorithm are compared to results from an Euler hydrocode simulation (CTH) and Velodyne simulations using the CONWEP algorithm.

  10. Simulation of optical breast density measurements using structured light illumination

    NASA Astrophysics Data System (ADS)

    Kwong, Jessica; Nouizi, Farouk; Li, Yifan; Chen, Jeon-Hor; Su, Min-Ying; Gulsen, Gultekin

    2014-02-01

    Breast density is a risk factor for breast cancer and we propose using diffuse optical tomography with structured light illuminations (SLI) to quantify the percentage of the fibroglandular (dense) tissue within the breast. Segmentations of dense tissue from breast MRI cases were used to create a geometric model of the breast. COMSOL-generated Finite Element Method (FEM) meshes were used for simulating photon migration through the breast tissue and reconstructing the absorption maps. In these preliminary simulations, the absorption coefficients of the non-dense and dense tissue were assigned using literature values based on their concentrations of water, lipid, oxy- and deoxyhemoglobin as they are the main chromophores, or absorbers of light, within the breast. Synthetic SLI measurements were obtained using a FEMbased forward solver. During the simulation, 12 distinct patterns consisting of vertical stripes, horizontal stripes, and checkerboard patterns were used for illumination and detection. Using these simulated measurements, FEM-based inverse solvers were used to reconstruct the 3D absorption maps. In this study, the methods are applied to reconstruct the absorption maps for multiple wavelengths (780nm, 830nm, 900nm, 1000nm) using one case as an example. We are currently continuing these simulations with additional cases and reconstructing 3D concentration maps of the chromophores within the dense and non-dense breast tissue.

  11. Deployment Simulation Methods for Ultra-Lightweight Inflatable Structures

    NASA Technical Reports Server (NTRS)

    Wang, John T.; Johnson, Arthur R.

    2003-01-01

    Two dynamic inflation simulation methods are employed for modeling the deployment of folded thin-membrane tubes. The simulations are necessary because ground tests include gravity effects and may poorly represent deployment in space. The two simulation methods are referred to as the Control Volume (CV) method and the Arbitrary Lagrangian Eulerian (ALE) method. They are available in the LS-DYNA nonlinear dynamic finite element code. Both methods are suitable for modeling the interactions between the inflation gas and the thin-membrane tube structures. The CV method only considers the pressure induced by the inflation gas in the simulation, while the ALE method models the actual flow of the inflation gas. Thus, the transient fluid properties at any location within the tube can be predicted by the ALE method. Deployment simulations of three packaged tube models; namely coiled, Z-folded, and telescopically-folded configurations, are performed. Results predicted by both methods for the telescopically-folded configuration are correlated and computational efficiency issues are discussed.

  12. Simulation of reactor pulses in fast burst and externally driven nuclear assemblies

    NASA Astrophysics Data System (ADS)

    Green, Taylor Caldwell, IV

    The following research contributes original concepts to the fields of deterministic neutron transport modeling and reactor power excursion simulation. A deterministic neutron transport code was created to assess the value of new methods of determining neutron current, fluence, and flux values through the use of view factor and average path length calculations. The neutron transport code is also capable of modeling the highly anisotropic neutron transport of deuterium-tritium fusion external source neutrons using diffusion theory with the aid of a modified first collision source term. The neutron transport code was benchmarked with MCNP, an industry standard stochastic neutron transport code. Deterministic neutron transport methods allow users to model large quantities of neutrons without simulating their interactions individually. Subsequently, deterministic methods allow users to more easily couple neutron transport simulations with other physics simulations. Heat transfer and thermoelastic mechanics physics simulation modules were each developed and benchmarked using COMSOL, a commercial heat transfer and mechanics simulation software. The physics simulation modules were then coupled and used to simulate reactor pulses in fast burst and externally driven nuclear assemblies. The coupled system of equations represents a new method of simulating reactor pulses that allows users to more fully characterize pulsed assemblies. Unlike older methods of reactor pulse simulation, the method presented in this research does not require data from the operational reactor in order to simulate its behavior. The ability to simulate the coupled neutron transport and thermo-mechanical feedback present in pulsed reactors prior their construction would significantly enhance the quality of pulsed reactor pre-construction safety analysis. Additionally, a graphical user interface is created to allow users to run simulations and visualize the results using the coupled physics simulation

  13. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet; Mohanty, B. P.; Saini, G. S. S.

    2016-02-01

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.

  14. Ab Initio Nuclear Structure and Reaction Calculations for Rare Isotopes

    SciTech Connect

    Draayer, Jerry P.

    2014-09-28

    We have developed a novel ab initio symmetry-adapted no-core shell model (SA-NCSM), which has opened the intermediate-mass region for ab initio investigations, thereby providing an opportunity for first-principle symmetry-guided applications to nuclear structure and reactions for nuclear isotopes from the lightest p-shell systems to intermediate-mass nuclei. This includes short-lived proton-rich nuclei on the path of X-ray burst nucleosynthesis and rare neutron-rich isotopes to be produced by the Facility for Rare Isotope Beams (FRIB). We have provided ab initio descriptions of high accuracy for low-lying (including collectivity-driven) states of isotopes of Li, He, Be, C, O, Ne, Mg, Al, and Si, and studied related strong- and weak-interaction driven reactions that are important, in astrophysics, for further understanding stellar evolution, X-ray bursts and triggering of s, p, and rp processes, and in applied physics, for electron and neutrino-nucleus scattering experiments as well as for fusion ignition at the National Ignition Facility (NIF).

  15. Pseudospin symmetry in nuclear structure and its supersymmetric representation

    NASA Astrophysics Data System (ADS)

    Liang, H. Z.

    2016-08-01

    The quasi-degeneracy between the single-particle states (n,l,j=l+1/2) and (n-1,l+2,j=l+3/2) indicates a special and hidden symmetry in atomic nuclei—the so-called pseudospin symmetry (PSS)—which is an important concept in both spherical and deformed nuclei. A number of phenomena in nuclear structure have been successfully interpreted directly or implicitly by this symmetry, including nuclear superdeformed configurations, identical bands, quantized alignment, pseudospin partner bands, and so on. Since the PSS was recognized as a relativistic symmetry in 1990s, there have been comprehensive efforts to understand its properties in various systems and potentials. In this review, we mainly focus on the latest progress on the supersymmetric (SUSY) representation of PSS, and one of the key targets is to understand its symmetry-breaking mechanism in realistic nuclei in a quantitative and perturbative way. The SUSY quantum mechanics and its applications to the SU(2) and U(3) symmetries of the Dirac Hamiltonian are discussed in detail. It is shown that the origin of PSS and its symmetry-breaking mechanism, which are deeply hidden in the origin Hamiltonian, can be traced by its SUSY partner Hamiltonian. Essential open questions, such as the SUSY representation of PSS in the deformed system, are pointed out.

  16. Nonlocalized clustering: a new concept in nuclear cluster structure physics.

    PubMed

    Zhou, Bo; Funaki, Y; Horiuchi, H; Ren, Zhongzhou; Röpke, G; Schuck, P; Tohsaki, A; Xu, Chang; Yamada, T

    2013-06-28

    We investigate the α+^{16}O cluster structure in the inversion-doublet band (Kπ=0(1)±}) states of 20Ne with an angular-momentum-projected version of the Tohsaki-Horiuchi-Schuck-Röpke (THSR) wave function, which was successful "in its original form" for the description of, e.g., the famous Hoyle state. In contrast with the traditional view on clusters as localized objects, especially in inversion doublets, we find that these single THSR wave functions, which are based on the concept of nonlocalized clustering, can well describe the Kπ=0(1)- band and the Kπ=0(1)+ band. For instance, they have 99.98% and 99.87% squared overlaps for 1- and 3- states (99.29%, 98.79%, and 97.75% for 0+, 2+, and 4+ states), respectively, with the corresponding exact solution of the α+16O resonating group method. These astounding results shed a completely new light on the physics of low energy nuclear cluster states in nuclei: The clusters are nonlocalized and move around in the whole nuclear volume, only avoiding mutual overlap due to the Pauli blocking effect. PMID:23848866

  17. Demonstrating Structural Adequacy of Nuclear Power Plant Containment Structures for Beyond Design-Basis Pressure Loadings

    SciTech Connect

    Braverman, J.I.; Morante, R.

    2010-07-18

    ABSTRACT Demonstrating the structural integrity of U.S. nuclear power plant (NPP) containment structures, for beyond design-basis internal pressure loadings, is necessary to satisfy Nuclear Regulatory Commission (NRC) requirements and performance goals. This paper discusses methods for demonstrating the structural adequacy of the containment for beyond design-basis pressure loadings. Three distinct evaluations are addressed: (1) estimating the ultimate pressure capacity of the containment structure (10 CFR 50 and US NRC Standard Review Plan, Section 3.8) ; (2) demonstrating the structural adequacy of the containment subjected to pressure loadings associated with combustible gas generation (10 CFR 52 and 10 CFR 50); and (3) demonstrating the containment structural integrity for severe accidents (10 CFR 52 as well as SECY 90-016, SECY 93-087, and related NRC staff requirements memoranda (SRMs)). The paper describes the technical basis for specific aspects of the methods presented. It also presents examples of past issues identified in licensing activities related to these evaluations.

  18. Extending the lifespan of nuclear power plant structures

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.

    1995-04-01

    By the end of this decade, 63 of the 111 commercial nuclear power plants in the United States will be more than 20 years old, with some nearing the end of their 40-year operating license term. Faced with the prospect of having to replace lost generating capacity from other sources and substantial shutdown and decommissioning costs, many utilities are expected to apply to continue the service of their plants past the initial licensing period. In support of such applications, evidence should be provided that the capacity of the safety-related systems and structures to mitigate potential extreme events has not deteriorated unacceptably due to either aging or environmental stressor effects during the previous service history.

  19. Numerical simulations of cloud rise phenomena associated with nuclear bursts: compressible and low Mach approaches

    NASA Astrophysics Data System (ADS)

    Kanarska, Y.; Lomov, I.; Antoun, T.

    2008-12-01

    The nuclear cloud rise is a two stage phenomenon. The initial phase (fireball expansion) of the cloud formation is dominated by compressible flow effects and propagation of shock waves. At the later stage, shock waves become weak, the Mach number decreases and the time steps required by an explicit code to model the acoustic waves make simulation of the late time cloud dynamics with a compressible code very expensive. The buoyant cloud rise at this stage can be efficiently simulated by low Mach-number approximation. In this approach acoustic waves are removed analytically, compressible effects are included as a non-zero divergence constraint due to background stratification and the system of equations is solved implicitly using pressure projection methods. Our numerical approach includes fluid mechanical models that are able to simulate both compressible, incompressible and low Mach regimes. Compressible dynamics is simulated with the explicit high order Eulerian code GEODYN (Lomov et al., 2001). It is based on the second-order Godunov method of Colella and Woodward (1984) that is extended for multiple dimensions using operator-splitting. The code includes the material interface tracking based on a volume-of-fluid (VOF) approach of Miller and Puckett (1996). The code we use for the low Mach approximation (LMC) is based on the incompressible solver of Bell et al., (2003). An unsplit second-order Godunov method and the MAC projection method (Bell et al., 2003) are used. An algebraic slip multiphase model is implemented to describe fallout of dust particles. Both codes incorporate adaptive mesh refinement (AMR). Additionally, the codes are explicitly coupled via input/output files. First, we compared solutions for an idealized buoyant bubble rise problem, that is characterized by low Mach numbers, in GEODYN and LMC codes. While the cloud evolution process is reproduced in both codes, some differences are found in the cloud rise speed and the cloud interface structure

  20. Nuclear structure and heavy-ion fusion. [Lecture

    SciTech Connect

    Stokstad, R.G.

    1980-10-01

    A series of lectures is presented on experimental studies of heavy-ion fusion reactions with emphasis on the role of nuclear structure in the fusion mechanism. The experiments considered are of three types: the fusion of lighter heavy ions at subcoulomb energies is studied with in-beam ..gamma..-ray techniques; the subbarrier fusion of /sup 16/O and /sup 40/Ar with the isotopes of samarium is detected out of beam by x-radiation from delayed activity; and measurements at very high energies, again for the lighter ions, employ direct particle identification of evaporation residues. The experimental data are compared with predictions based on the fusion of two spheres with the only degree of freedom being the separation of the centers, and which interact via potentials that vary smoothly with changes in the mass and charge of the projectile and target. The data exhibit with the isotopes of samarium, a portion of these deviations can be understood in terms of the changing deformation of the target nucleus, but an additional degree of freedom such as neck formation appears necessary. The results on /sup 10/B + /sup 16/O and /sup 12/C + /sup 14/N ..-->.. /sup 26/Al at high bombarding energies indicate a maximum limiting angular momentum characteristic of the compound nucleus. At lower energies the nuclear structure of the colliding ion seems to affect strongly the cross section for fusion. Measurements made at subbarrier energies for a variety of projectile-target combinations in the 1p and 2s - 1d shell also indicate that the valence nucleons can affect the energy dependence for fusion. About half the systems studied so far have structureless excitation functions which follow a standard prediction. The other half exhibit large variations from this prediction. The possible importance of neutron transfer is discussed. The two-center shell model appears as a promising approach for gaining a qualitative understanding of these phenomena. 95 references, 52 figures, 1 table.

  1. Implementation and application of a dual structure model for simulating the behavior of expansive soils

    NASA Astrophysics Data System (ADS)

    Vilarrasa, V.; Rutqvist, J.; Zheng, L.

    2013-12-01

    We have implemented a constitutive model for unsaturated expansive soils in FLAC3D. The main feature of this constitutive model is the consideration of two pore levels: a microstructure that accounts for the active clay minerals and a macrostructure related to major structural rearrangement. The microstructure behaves elastically, while the macrostructure can undergo irreversible strain. The two structural levels interact between them, which allows simulating irreversible strain accumulation upon suction cycles. Strain accumulation can be either an expansion, if the state of compaction of the macrostructure is low, because macroporosity develops upon suction cycles, or a compaction, if the state of compaction of the macrostructure is high, as a result of microspores invading macropores. This model can be linked to chemistry by accounting for the effect of cation exchange on the stiffness of the microstructure. We have verified the implementation of this model by comparing our results with published numerical simulations and laboratory experiments. We have applied this dual structure model using THOUGHREACT-FLAC to simulate the thermo-hydro-mechanical-chemical behavior of bentonite-sand mixtures, which are being considered as back-fill and buffer materials for geologic nuclear waste disposal.

  2. Simulation and Experimental Validation of Electromagnetic Signatures for Monitoring of Nuclear Material Storage Containers

    SciTech Connect

    Aker, Pamela M.; Bunch, Kyle J.; Jones, Anthony M.

    2013-01-01

    Previous research at the Pacific Northwest National Laboratory (PNNL) has demonstrated that the low frequency electromagnetic (EM) response of a sealed metallic container interrogated with an encircling coil is a strong function of its contents and can be used to form a distinct signature which can confirm the presence of specific components without revealing hidden geometry or classified design information. Finite element simulations have recently been performed to further investigate this response for a variety of configurations composed of an encircling coil and a typical nuclear material storage container. Excellent agreement was obtained between simulated and measured impedance signatures of electrically conducting spheres placed inside an AT-400R nuclear container. Simulations were used to determine the effects of excitation frequency and the geometry of the encircling coil, nuclear container, and internal contents. The results show that it is possible to use electromagnetic models to evaluate the application of the EM signature technique to proposed versions of nuclear weapons containers which can accommodate restrictions imposed by international arms control and treaty verification legislation.

  3. Modeling and Testing of Non-Nuclear, Highpower Simulated Nuclear Thermal Rocket Reactor Elements

    NASA Technical Reports Server (NTRS)

    Kirk, Daniel R.

    2005-01-01

    When the President offered his new vision for space exploration in January of 2004, he said, "Our third goal is to return to the moon by 2020, as the launching point for missions beyond," and, "With the experience and knowledge gained on the moon, we will then be ready to take the next steps of space exploration: human missions to Mars and to worlds beyond." A human mission to Mars implies the need to move large payloads as rapidly as possible, in an efficient and cost-effective manner. Furthermore, with the scientific advancements possible with Project Prometheus and its Jupiter Icy Moons Orbiter (JIMO), (these use electric propulsion), there is a renewed interest in deep space exploration propulsion systems. According to many mission analyses, nuclear thermal propulsion (NTP), with its relatively high thrust and high specific impulse, is a serious candidate for such missions. Nuclear rockets utilize fission energy to heat a reactor core to very high temperatures. Hydrogen gas flowing through the core then becomes superheated and exits the engine at very high exhaust velocities. The combination of temperature and low molecular weight results in an engine with specific impulses above 900 seconds. This is almost twice the performance of the LOX/LH2 space shuttle engines, and the impact of this performance would be to reduce the trip time of a manned Mars mission from the 2.5 years, possible with chemical engines, to about 12-14 months.

  4. Monte Carlo Simulation Study of a Differential Calorimeter Measuring the Nuclear Heating in Material Testing Reactors

    NASA Astrophysics Data System (ADS)

    Amharrak, H.; Reynard-Carette, C.; Lyoussi, A.; Carette, M.; Brun, J.; De Vita, C.; Fourmentel, D.; Villard, J.-F.; Guimbal, P.

    2016-02-01

    The nuclear heating measurements in Material Testing Reactors (MTRs) are crucial for the study of nuclear materials and fuels under irradiation. The reference measurements of this nuclear heating are especially performed by a differential calorimeter including a graphite sample material. Then these measurements are used for other materials, other geometries, or other experimental conditions in order to predict the nuclear heating and thermal conditions induced in the irradiation devices. This paper will present new simulations with MCNP Monte-Carlo transport code to determine the gamma heating profile inside the calorimeter. The whole complex geometry of the sensor has been considered. We use as an input source in the model, the photon spectra calculated in various positions of CARMEN-1 irradiation program in OSIRIS reactor. After a description of the differential calorimeter device, the MCNP modeling used for the calculations of radial profile of nuclear heating inside the calorimeter elements will be introduced. The obtained results of different simulations will be detailed and discussed in this paper. The charged particle equilibrium inside the calorimeter elements will be studied. Then we will focus on parametric studies of the various components of the calorimeter. The influence of source type will be also took into account. Moreover the influence of the material used for the sample will be described.

  5. Diverse structural evolution at z > 1 in cosmologically simulated galaxies

    NASA Astrophysics Data System (ADS)

    Snyder, Gregory F.; Lotz, Jennifer; Moody, Christopher; Peth, Michael; Freeman, Peter; Ceverino, Daniel; Primack, Joel; Dekel, Avishai

    2015-08-01

    From mock Hubble Space Telescope images, we quantify non-parametric statistics of galaxy morphology, thereby predicting the emergence of relationships among stellar mass, star formation, and observed rest-frame optical structure at 1 < z < 3. We measure automated diagnostics of galaxy morphology in cosmological simulations of the formation of 22 central galaxies with 9.3 < log10M*/M⊙ < 10.7. These high-spatial-resolution zoom-in calculations enable accurate modelling of the rest-frame UV and optical morphology. Even with small numbers of galaxies, we find that structural evolution is neither universal nor monotonic: galaxy interactions can trigger either bulge or disc formation, and optically bulge-dominated galaxies at this mass may not remain so forever. Simulated galaxies with M* > 1010M⊙ contain relatively more disc-dominated light profiles than those with lower mass, reflecting significant disc brightening in some haloes at 1 < z < 2. By this epoch, simulated galaxies with specific star formation rates below 10- 9.7 yr- 1 are more likely than normal star-formers to have a broader mix of structural types, especially at M* > 1010 M⊙. We analyse a cosmological major merger at z ˜ 1.5 and find that the newly proposed Multimode-Intensity-Deviation (MID) morphology diagnostics trace later merger stages while Gini-M20 trace earlier ones. MID is sensitive also to clumpy star-forming discs. The observability time of typical MID-enhanced events in our simulation sample is <100 Myr. A larger sample of cosmological assembly histories may be required to calibrate such diagnostics in the face of their sensitivity to viewing angle, segmentation algorithm, and various phenomena such as clumpy star formation and minor mergers.

  6. Amyloid oligomer structure characterization from simulations: A general method

    SciTech Connect

    Nguyen, Phuong H.; Li, Mai Suan

    2014-03-07

    Amyloid oligomers and plaques are composed of multiple chemically identical proteins. Therefore, one of the first fundamental problems in the characterization of structures from simulations is the treatment of the degeneracy, i.e., the permutation of the molecules. Second, the intramolecular and intermolecular degrees of freedom of the various molecules must be taken into account. Currently, the well-known dihedral principal component analysis method only considers the intramolecular degrees of freedom, and other methods employing collective variables can only describe intermolecular degrees of freedom at the global level. With this in mind, we propose a general method that identifies all the structures accurately. The basis idea is that the intramolecular and intermolecular states are described in terms of combinations of single-molecule and double-molecule states, respectively, and the overall structures of oligomers are the product basis of the intramolecular and intermolecular states. This way, the degeneracy is automatically avoided. The method is illustrated on the conformational ensemble of the tetramer of the Alzheimer's peptide Aβ{sub 9−40}, resulting from two atomistic molecular dynamics simulations in explicit solvent, each of 200 ns, starting from two distinct structures.

  7. Neutrino-pair emission from nuclear de-excitation in core-collapse supernova simulations

    NASA Astrophysics Data System (ADS)

    Fischer, T.; Langanke, K.; Martínez-Pinedo, G.

    2013-12-01

    We study the impact of neutrino-pair production from the de-excitation of highly excited heavy nuclei on core-collapse supernova simulations, following the evolution up to several 100 ms after core bounce. Our study is based on the agile-boltztransupernova code, which features general relativistic radiation hydrodynamics and accurate three-flavor Boltzmann neutrino transport in spherical symmetry. In our simulations the nuclear de-excitation process is described in two different ways. At first we follow the approach proposed by Fuller and Meyer [Astrophys. J.AJLEEY0004-637X10.1086/170317 376, 701 (1991)], which is based on strength functions derived in the framework of the nuclear Fermi-gas model of noninteracting nucleons. Second, we parametrize the allowed and forbidden strength distributions in accordance with measurements for selected nuclear ground states. We determine the de-excitation strength by applying the Brink hypothesis and detailed balance. For both approaches, we find that nuclear de-excitation has no effect on the supernova dynamics. However, we find that nuclear de-excitation is the leading source for the production of electron antineutrinos as well as heavy-lepton-flavor (anti)neutrinos during the collapse phase. At sufficiently high densities, the associated neutrino spectra are influenced by interactions with the surrounding matter, making proper simulations of neutrino transport important for the determination of the neutrino-energy loss rate. We find that, even including nuclear de-excitations, the energy loss during the collapse phase is overwhelmingly dominated by electron neutrinos produced by electron capture.

  8. Unconstrained Structure Formation in Coarse-Grained Protein Simulations

    NASA Astrophysics Data System (ADS)

    Bereau, Tristan

    The ability of proteins to fold into well-defined structures forms the basis of a wide variety of biochemical functions in and out of the cell membrane. Many of these processes, however, operate at time- and length-scales that are currently unattainable by all-atom computer simulations. To cope with this difficulty, increasingly more accurate and sophisticated coarse-grained models are currently being developed. In the present thesis, we introduce a solvent-free coarse-grained model for proteins. Proteins are modeled by four beads per amino acid, providing enough backbone resolution to allow for accurate sampling of local conformations. It relies on simple interactions that emphasize structure, such as hydrogen bonds and hydrophobicity. Realistic alpha/beta content is achieved by including an effective nearest-neighbor dipolar interaction. Parameters are tuned to reproduce both local conformations and tertiary structures. By studying both helical and extended conformations we make sure the force field is not biased towards any particular secondary structure. Without any further adjustments or bias a realistic oligopeptide aggregation scenario is observed. The model is subsequently applied to various biophysical problems: (i) kinetics of folding of two model peptides, (ii) large-scale amyloid-beta oligomerization, and (iii) protein folding cooperativity. The last topic---defined by the nature of the finite-size thermodynamic transition exhibited upon folding---was investigated from a microcanonical perspective: the accurate evaluation of the density of states can unambiguously characterize the nature of the transition, unlike its corresponding canonical analysis. Extending the results of lattice simulations and theoretical models, we find that it is the interplay between secondary structure and the loss of non-native tertiary contacts which determines the nature of the transition. Finally, we combine the peptide model with a high-resolution, solvent-free, lipid

  9. Modeling bistable behaviors in morphing structures through finite element simulations.

    PubMed

    Guo, Qiaohang; Zheng, Huang; Chen, Wenzhe; Chen, Zi

    2014-01-01

    Bistable structures, exemplified by the Venus flytrap and slap bracelets, can transit between different configurations upon certain external stimulation. Here we study, through three-dimensional finite element simulations, the bistable behaviors in elastic plates in the absence of terminate loads, but with pre-strains in one (or both) of the two composite layers. Both the scenarios with and without a given geometric mis-orientation angle are investigated, the results of which are consistent with recent theoretical and experimental studies. This work can open ample venues for programmable designs of plant/shell structures with large deformations, with applications in designing bio-inspired robotics for biomedical research and morphing/deployable structures in aerospace engineering. PMID:24211939

  10. Simulations of Relativistic Collisionless Shocks: Shock Structure and Particle Acceleration

    SciTech Connect

    Spitkovsky, Anatoly; /KIPAC, Menlo Park

    2006-04-10

    We discuss 3D simulations of relativistic collisionless shocks in electron-positron pair plasmas using the particle-in-cell (PIC) method. The shock structure is mainly controlled by the shock's magnetization (''sigma'' parameter). We demonstrate how the structure of the shock varies as a function of sigma for perpendicular shocks. At low magnetizations the shock is mediated mainly by the Weibel instability which generates transient magnetic fields that can exceed the initial field. At larger magnetizations the shock is dominated by magnetic reflections. We demonstrate where the transition occurs and argue that it is impossible to have very low magnetization collisionless shocks in nature (in more than one spatial dimension). We further discuss the acceleration properties of these shocks, and show that higher magnetization perpendicular shocks do not efficiently accelerate nonthermal particles in 3D. Among other astrophysical applications, this may pose a restriction on the structure and composition of gamma-ray bursts and pulsar wind outflows.

  11. Analysis of forest structure using thematic mapper simulator data

    NASA Technical Reports Server (NTRS)

    Peterson, D. L.; Westman, W. E.; Brass, J. A.; Stephenson, N. J.; Ambrosia, V. G.; Spanner, M. A.

    1986-01-01

    The potential of Thematic Mapper Simulator (TMS) data for sensing forest structure information has been explored by principal components and feature selection techniques. In a survey of forest structural properties conducted for 123 field sites of the Sequoia National Park, the canopy closure could be well estimated (r = 0.62 to 0.69) by a variety of channel bands and band ratios, without reference to the forest type. Estimation of the basal area was less successful (r = 0.51 or less) on the average, but could be improved for certain forest types when data were stratified by floristic composition. To achieve such a stratification, individual sites were ordinated by a detrended correspondence analysis based on the canopy of dominant species. The analysis of forest structure in the Sequoia data suggests that total basal area can be best predicted in stands of lower density, and in younger even-aged managed stands.

  12. Limits on the experimental simulation of nuclear fuel rod response. [PWR

    SciTech Connect

    Hagar, R.C.

    1980-01-01

    The steady-state and transient effects of intrinxic geometric and material property differences between typical nuclear fuel pins and electric fuel pin simulators (FPSs) are identified. The effectiveness of varying the transient power supplied to the FPS in reducing the differences between the transient responses of nuclear fuel pins and FPSs is investigated. This effectiveness is shown to be limited by the heat capacity of the FPS, the allowed range of the power program, and different FPS power requirements at different positions on a full-length FPS.

  13. Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)

    SciTech Connect

    Rich Johnson; Kimberlyn C. Mousseau; Hyung Lee

    2011-09-01

    NE-KAMS knowledge base will assist computational analysts, physics model developers, experimentalists, nuclear reactor designers, and federal regulators by: (1) Establishing accepted standards, requirements and best practices for V&V and UQ of computational models and simulations, (2) Establishing accepted standards and procedures for qualifying and classifying experimental and numerical benchmark data, (3) Providing readily accessible databases for nuclear energy related experimental and numerical benchmark data that can be used in V&V assessments and computational methods development, (4) Providing a searchable knowledge base of information, documents and data on V&V and UQ, and (5) Providing web-enabled applications, tools and utilities for V&V and UQ activities, data assessment and processing, and information and data searches. From its inception, NE-KAMS will directly support nuclear energy research, development and demonstration programs within the U.S. Department of Energy (DOE), including the Consortium for Advanced Simulation of Light Water Reactors (CASL), the Nuclear Energy Advanced Modeling and Simulation (NEAMS), the Light Water Reactor Sustainability (LWRS), the Small Modular Reactors (SMR), and the Next Generation Nuclear Power Plant (NGNP) programs. These programs all involve computational modeling and simulation (M&S) of nuclear reactor systems, components and processes, and it is envisioned that NE-KAMS will help to coordinate and facilitate collaboration and sharing of resources and expertise for V&V and UQ across these programs. In addition, from the outset, NE-KAMS will support the use of computational M&S in the nuclear industry by developing guidelines and recommended practices aimed at quantifying the uncertainty and assessing the applicability of existing analysis models and methods. The NE-KAMS effort will initially focus on supporting the use of computational fluid dynamics (CFD) and thermal hydraulics (T/H) analysis for M&S of nuclear

  14. Correlating simulated surface marks with near-surface tornado structure

    NASA Astrophysics Data System (ADS)

    Zimmerman, Michael I.

    Tornadoes often leave behind patterns of debris deposition, or "surface marks", which provide a direct signature of their near surface winds. The intent of this thesis is to investigate what can be learned about near-surface tornado structure and intensity through the properties of surface marks generated by simulated, debris-laden tornadoes. Earlier work showed through numerical simulations that the tornado's structure and intensity is highly sensitive to properties of the near-surface flow and can change rapidly in time for some conditions. The strongest winds often occur within tens of meters of the surface where the threat to human life and property is highest, and factors such as massive debris loadings and asymmetry of the main vortex have proven to be critical complications in some regimes. However, studying this portion of the flow in the field is problematic; while Doppler radar provides the best tornado wind field measurements, it cannot probe below about 20 m, and interpretation of Doppler data requires assumptions about tornado symmetry, steadiness in time, and correlation between scatterer and air velocities that are more uncertain near the surface. As early as 1967, Fujita proposed estimating tornado wind speeds from analysis of aerial photography and ground documentation of surface marks. A handful of studies followed but were limited by difficulties in interpreting physical origins of the marks, and little scientific attention has been paid to them since. Here, Fujita's original idea is revisited in the context of three-dimensional, large-eddy simulations of tornadoes with fully-coupled debris. In this thesis, the origins of the most prominent simulated marks are determined and compared with historical interpretations of real marks. The earlier hypothesis that cycloidal surface marks were directly correlated with the paths of individual vortices (either the main vortex or its secondary vortices, when present) is unsupported by the simulation results

  15. Detection of Coherent Structures in Extreme-Scale Simulations

    SciTech Connect

    Kamath, C; Iverson, J; Kirk, R; Karypis, G

    2012-03-24

    The analysis of coherent structures is a common problem in many scientific domains ranging from astrophysics to combustion, fusion, and materials science. The data from three-dimensional simulations are analyzed to detect the structures, extract statistics on them, and track them over time to gain insights into the phenomenon being modeled. This analysis is typically done off-line, using data that have been written out by the simulations. However, the move towards extreme scale architectures, with multi-core processors and graphical processing units, will affect how such analysis is done as it is unlikely that the systems will support the I/O bandwidth required for off-line analysis. Moving the analysis in-situ is a solution only if we know a priori what analysis will be done, as well as the algorithms used and their parameter settings. Even then, we need to ensure that this will not substantially increase the memory requirements or the data movement as the former will be limited and the latter will be expensive. In the Exa-DM project, a collaboration between Lawrence Livermore National Laboratory and University of Minnesota, we are exploring ways in which we can address the conflicting demands of coherent structure analysis of simulation data and the architecture of modern parallel systems, while enabling scientific discovery at the exascale. In this paper, we describe our work in two areas: the in situ implementation of an existing algorithm for coherent structure analysis and the use of graph-based techniques to efficiently compress the data.

  16. Design Considerations for the Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    NASA Technical Reports Server (NTRS)

    Emrich, Bill; Kirk, Daniel

    2006-01-01

    Nuclear Thermal Rockets or NTR's have been suggested as a propulsion system option for vehicles traveling to the moon or Mars. These engines are capable of providing high thrust at specific impulses at least twice that of today s best chemical engines. The performance constraints on these engines are mainly the result of temperature limitations on the fuel coupled with a limited ability to withstand chemical attack by the hot hydrogen propellant. To operate at maximum efficiency, fuel forms are desired which can withstand the extremely hot, hostile environment characteristic of NTR operation for at least several hours. The simulation of such an environment would require an experimental device which could simultaneously approximate the power, flow, and temperature conditions which a nuclear fuel element (or partial element) would encounter during NTR operation. Such a simulation would allow detailed studies of the fuel behavior and hydrogen flow characteristics under reactor like conditions to be performed. The goal of these simulations would be directed toward expanding the performance envelope of NTR engines over that which was demonstrated during the Rover and NERVA nuclear rocket programs of the 1970's. Currently, such a simulator is nearing completion at the Marshall Space Flight Center, and will shortly be used in the future to evaluate a wide variety of he1 element designs and the materials of which they are constructed. This present work addresses the initial experimental objectives of the Nuclear Thermal Rocket Element Environmental Simulator or NTREES and some of the design considerations which were considered prior to and during its construction.

  17. Numerical simulations of waves in a magnetically structured atmosphere

    NASA Astrophysics Data System (ADS)

    Espinola, Thomas Peter

    A physical model for simulating waves in a stellar atmosphere was developed from a combination of basic fluid mechanics, plasma physics, and electrodynamics. The model was three dimensional and included the effects of gravity, magnetic fields, and viscosity. An algorithm was developed to numerically implement this model. The resulting program used an explicit time integration scheme based on Runge-Kutta and a combination of finite difference and spectral methods to evaluate the spatial derivatives. A number of numerical boundary conditions were developed—the most successful used a modified Sommerfeld radiation condition. The program was written and coded in Fortran on a Vax computer. Additional routines were written to evaluate the required fast fourier transforms and to graph and display the data. The program was tested on a large number of one and two dimensional problems for which the solutions were known. These problems included acoustic waves, Alfvén waves, magnetoacoustic waves, shocks, rarefactions, and contact discontinuities. The numerical results agreed with the analytic solutions of the physical problems to within the precision requested of the simulation. The program proved to be stable and robust for all the problems attempted. This program was then used to simulate three problems for which analytic solutions are not known. All three simulations concerned the propagation of waves in magnetically structured atmospheres and may be applied to outstanding problems in solar physics. First, the interactions of non-linear waves and a flux slab were studied. From the result it is apparent that sources of shocks and rarefactions, such as the solar convection zone, do not concentrate the magnetic field in flux sheaths. Next I used the program to simulate the interaction of non-linear waves with a flux tube. The results suggest that the magnetic fields in flux tubes are also not concentrated by pairs of passing shocks and rarefactions; however, a complete

  18. NUCLEAR REACTION AND STRUCTURE DATABASES OF THE NATIONAL NUCLEAR DATA CENTER.

    SciTech Connect

    PRITYCHENKO, B.; HERMAN, M.W.; MUGHABGHAB, S.F.; OBLOZINSKY, P.; SONZOGNI, A.A.

    2006-06-23

    We discuss nuclear data resources of the National Nuclear Data Center (NNDC) of relevance to nuclear astrophysics applications. These resources include databases, tools and powerful web service at www.nndc.bnl.gov. Our objective is to provide an overview of nuclear databases, related products and demonstrate nuclear astrophysics potential of the ENDF/B-VII beta2 library. A detailed discussion on the Maxwellian neutron capture cross sections obtained from the ENDF/B-VII beta2 library is presented.

  19. Physics with gamma-beams and charged particle detectors: I) Nuclear structure II) Nuclear astrophysics

    SciTech Connect

    Gai, Moshe

    2015-02-24

    The Charged Particle Working Group (CPWG) is proposing to construct large area Silicon Strip Detector (SSD), a gas Time Projection Chamber detector read by an electronic readout system (eTPC) and a Bubble Chamber (BC) containing superheated high purity water to be used in measurements utilizing intense gamma-ray beams from the newly constructed ELI-NP facility at Magurele, Bucharest in Romania. We intend to use the SSD and eTPC detectors to address essential problems in nuclear structure physics, such as clustering and the many alpha-decay of light nuclei such as {sup 12}C and {sup 16}O. All three detectors (SSD, eTPC and BC) will be used to address central problems in nuclear astrophysics such as the astrophysical cross section factor of the {sup 12}C(α,γ) reaction and other processes central to stellar evolution. The CPWG intends to submit to the ELI-NP facility a Technical Design Report (TDR) for the proposed detectors.

  20. Physics with gamma-beams and charged particle detectors: I) Nuclear structure II) Nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2015-02-01

    The Charged Particle Working Group (CPWG) is proposing to construct large area Silicon Strip Detector (SSD), a gas Time Projection Chamber detector read by an electronic readout system (eTPC) and a Bubble Chamber (BC) containing superheated high purity water to be used in measurements utilizing intense gamma-ray beams from the newly constructed ELI-NP facility at Magurele, Bucharest in Romania. We intend to use the SSD and eTPC detectors to address essential problems in nuclear structure physics, such as clustering and the many alpha-decay of light nuclei such as 12C and 16O . All three detectors (SSD, eTPC and BC) will be used to address central problems in nuclear astrophysics such as the astrophysical cross section factor of the 12C (α,γ) reaction and other processes central to stellar evolution. The CPWG intends to submit to the ELI-NP facility a Technical Design Report (TDR) for the proposed detectors.

  1. Numerical Simulation of the Seismic Response for the Recent North Korean Nuclear Tests (Invited)

    NASA Astrophysics Data System (ADS)

    Rodgers, A. J.; Vorobiev, O.; Petersson, A.; Sjogreen, B.; Matzel, E.

    2009-12-01

    We performed a series of numerical simulations of the 2006 and 2009 North Korean nuclear tests to model the observed seismic data and gain insight into the wave propagation phenomena that may impact source estimates of these events, such as the waveform shapes and amplitudes of direct P-waves, the generation of S-waves, high-frequency P/S ratios. Simulations span the hydrodynamic (near-field, non-linear), local and regional distance ranges, although seismic data are only available for regional and teleseismic distances. Firstly, we modeled the response of the immediate near-field assuming emplacement in granite for small explosions (yields 0.5-3 kiloton) with GEODYN, an Eulerian finite-volume hydrodynamics code. This is a rather hard material that results in an impulsive short duration source time function and small cavity. Secondly, we modeled the elastic response of simple earth models including free surface topography with WPP (an anelastic finite difference code) for a domain ~20 km around the sources. Topographic relief is significant at the test site, with elevations rising from 300 m to 2000 m over short distances. We found that the inclusion of topography has a strong impact on the wavefield, causing azimuthal dependence of both the P-wave scattering and S-wave generation. Furthermore, the scattering by the rough free-surface causes decorrelation of the emerging P-waves for the 2006 and 2009 events, spaced only ~4 km apart. Thirdly, we simulated seismic wave propagation to regional distances (< 2000 km) using three-dimensional (3D) wavespeed models and SPECFEM3D, a spectral element code, and compared results with the available long-period waveforms. We used the source models of Dreger et al. (manuscript submitted) and find that the synthetics for 3D models and an isotropic source predict some features of the observed waveforms. The one-dimensional (1D) iasp91 (Kennett and Engdahl, 1991) model performs surprisingly well for the vertical and radial component

  2. Activities in support of continuing the service of nuclear power plant concrete structures

    SciTech Connect

    Naus, Dan J

    2012-01-01

    In general, nuclear power plant concrete structure s performance has been very good; however, aging of concrete structures occurs with the passage of time that can potentially result in degradation if is effects are not controlled. Safety-related nuclear power plant concrete structures are described. In-service inspection and testing requirements in the U.S. are summarized. The interaction of the license renewal process and concrete structures is noted. A summary of operating experience related to aging of nuclear power plant concrete structures is provided. Several candidate areas are identified where additional research would be beneficial for aging management of nuclear power plant concrete structures. Finally, an update on recent activities at Oak Ridge National Laboratory related to aging management of nuclear power plant concrete structures is provided.

  3. Effect of Particle Size Distribution on Slurry Rheology: Nuclear Waste Simulant Slurries

    SciTech Connect

    Chun, Jaehun; Oh, Takkeun; Luna, Maria L.; Schweiger, Michael J.

    2011-07-05

    Controlling the rheological properties of slurries has been of great interest in various industries such as cosmetics, ceramic processing, and nuclear waste treatment. Many physicochemical parameters, such as particle size, pH, ionic strength, and mass/volume fraction of particles, can influence the rheological properties of slurry. Among such parameters, the particle size distribution of slurry would be especially important for nuclear waste treatment because most nuclear waste slurries show a broad particle size distribution. We studied the rheological properties of several different low activity waste nuclear simulant slurries having different particle size distributions under high salt and high pH conditions. Using rheological and particle size analysis, it was found that the percentage of colloid-sized particles in slurry appears to be a key factor for rheological characteristics and the efficiency of rheological modifiers. This behavior was shown to be coupled with an existing electrostatic interaction between particles under a low salt concentration. Our study suggests that one may need to implement the particle size distribution as a critical factor to understand and control rheological properties in nuclear waste treatment plants, such as the U.S. Department of Energy’s Hanford and Savannah River sites, because the particle size distributions significantly vary over different types of nuclear waste slurries.

  4. Structural and Functional Insight into Proliferating Cell Nuclear Antigen.

    PubMed

    Park, So Young; Jeong, Mi Suk; Han, Chang Woo; Yu, Hak Sun; Jang, Se Bok

    2016-04-28

    Proliferating cell nuclear antigen (PCNA) is a critical eukaryotic replication accessory factor that supports DNA binding in DNA processing, such as DNA replication, repair, and recombination. PCNA consists of three toroidal-shaped monomers that encircle doublestranded DNA. The diverse functions of PCNA may be regulated by its interactions with partner proteins. Many of the PCNA partner proteins generally have a conserved PCNAinteracting peptide (PIP) motif, located at the N- or C- terminal region. The PIP motif forms a 310 helix that enters into the hydrophobic groove produced by an interdomain-connecting loop, a central loop, and a C-terminal tail in the PCNA. Post-translational modification of PCNA also plays a critical role in regulation of its function and binding partner proteins. Structural and biochemical studies of PCNA-protein will be useful in designing therapeutic agents, as well as estimating the outcome of anticancer drug development. This review summarizes the characterization of eukaryotic PCNA in relation to the protein structures, functions, and modifications, and interaction with proteins. PMID:26699741

  5. Understanding the proton radius puzzle: Nuclear structure effects in light muonic atoms

    NASA Astrophysics Data System (ADS)

    Ji, Chen; Hernandez, Oscar Javier; Nevo Dinur, Nir; Bacca, Sonia; Barnea, Nir

    2016-03-01

    We present calculations of nuclear structure effects to the Lamb shift in light muonic atoms. We adopt a modern ab-initio approach by combining state-of-the-art nuclear potentials with the hyperspherical harmonics method. Our calculations are instrumental to the determination of nuclear charge radii in the Lamb shift measurements, which will shed light on the proton radius puzzle.

  6. 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.

  7. 3D Ultrasonic Wave Simulations for Structural Health Monitoring

    NASA Technical Reports Server (NTRS)

    Campbell, Leckey Cara A/; Miler, Corey A.; Hinders, Mark K.

    2011-01-01

    Structural health monitoring (SHM) for the detection of damage in aerospace materials is an important area of research at NASA. Ultrasonic guided Lamb waves are a promising SHM damage detection technique since the waves can propagate long distances. For complicated flaw geometries experimental signals can be difficult to interpret. High performance computing can now handle full 3-dimensional (3D) simulations of elastic wave propagation in materials. We have developed and implemented parallel 3D elastodynamic finite integration technique (3D EFIT) code to investigate ultrasound scattering from flaws in materials. EFIT results have been compared to experimental data and the simulations provide unique insight into details of the wave behavior. This type of insight is useful for developing optimized experimental SHM techniques. 3D EFIT can also be expanded to model wave propagation and scattering in anisotropic composite materials.

  8. SNM-DAT: Simulation of a heterogeneous network for nuclear border security

    NASA Astrophysics Data System (ADS)

    Nemzek, R.; Kenyon, G.; Koehler, A.; Lee, D. M.; Priedhorsky, W.; Raby, E. Y.

    2007-08-01

    We approach the problem of detecting Special Nuclear Material (SNM) smuggling across open borders by modeling a heterogeneous sensor network using an agent-based simulation. Our simulation SNM Data Analysis Tool (SNM-DAT) combines fixed seismic, metal, and radiation detectors with a mobile gamma spectrometer. Decision making within the simulation determines threat levels by combined signatures. The spectrometer is a limited-availability asset, and is only deployed for substantial threats. "Crossers" can be benign or carrying shielded SNM. Signatures and sensors are physics based, allowing us to model realistic sensor networks. The heterogeneous network provides great gains in detection efficiency compared to a radiation-only system. We can improve the simulation through better sensor and terrain models, additional signatures, and crossers that mimic actual trans-border traffic. We expect further gains in our ability to design sensor networks as we learn the emergent properties of heterogeneous detection, and potential adversary responses.

  9. Visualizing microscopic structure and dynamics of simulated silicate melts

    NASA Astrophysics Data System (ADS)

    Karki, B. B.; Bohara, B.

    2013-12-01

    We perform a detailed visualization-based analysis of atomic-position series data for silicate melts obtained from first-principles (quantum mechanical) molecular dynamics simulations. This involves processing atomic trajectories as well as relevant structural and dynamical information. Clutter associated with trajectory rendering can be reduced with an adaptive position-merging scheme. To gain insight into the short- and mid-range order of the melt structure, we extract and visualize the details of radial distribution function (RDF) and coordination environment. The first peaks of all partial RDFs lie in the distance range of 1.6 to 4 Å and the corresponding mean coordination numbers vary from less than 1 to more than 9. The coordination environments involving cations and anions differ substantially from each other, each consisting of a rich set of coordination states. These states vary both spatially and temporally: The per-atom coordination information extracted on the fly is rendered instantaneously as the spheres and polyhedra as well as along the corresponding trajectories using a color-coding scheme. The information is also visualized as clusters formed by atoms that are coordinated at different time intervals during the entire simulation. The animated visualization suggests that the melt structure can be viewed as a dynamic (partial) network of Al/Si-O coordination polyhedra connected via bridging oxygen in an inhomogeneous distribution of mobile cations including magnesium, calcium, and protons.

  10. Detailed Multidimensional Simulations of the Structure and Dynamics of Flames

    NASA Technical Reports Server (NTRS)

    Patnaik, G.; Kailasanath, K.

    1999-01-01

    Numerical simulations in which the various physical and chemical processes can be independently controlled can significantly advance our understanding of the structure, stability, dynamics and extinction of flames. Therefore, our approach has been to use detailed time-dependent, multidimensional, multispecies numerical models to perform carefully designed computational experiments of flames on Earth and in microgravity environments. Some of these computational experiments are complementary to physical experiments performed under the Microgravity Program while others provide a fundamental understanding that cannot be obtained from physical experiments alone. In this report, we provide a brief summary of our recent research highlighting the contributions since the previous microgravity combustion workshop. There are a number of mechanisms that can cause flame instabilities and result in the formation of dynamic multidimensional structures. In the past, we have used numerical simulations to show that it is the thermo-diffusive instability rather than an instability due to preferential diffusion that is the dominant mechanism for the formation of cellular flames in lean hydrogen-air mixtures. Other studies have explored the role of gravity on flame dynamics and extinguishment, multi-step kinetics and radiative losses on flame instabilities in rich hydrogen-air flames, and heat losses on burner-stabilized flames in microgravity. The recent emphasis of our work has been on exploring flame-vortex interactions and further investigating the structure and dynamics of lean hydrogen-air flames in microgravity. These topics are briefly discussed after a brief discussion of our computational approach for solving these problems.

  11. Fluid-structure Interaction Simulations of Deformable Soft Tissue

    NASA Astrophysics Data System (ADS)

    Borazjani, Iman

    2011-11-01

    Soft tissue interacts with the surrounding fluid environment in many biological and biomedical applications. Simulating such an interaction is quite challenging due to the large non-linear deformations of tissue, flow pulsatility, transition to turbulence, and non-linear fluid-structure interaction. We have extended our previous three-dimensional fluid-structure interaction (FSI) framework for rigid bodies (Borazjani, Ge, and Sotiropoulos, Journal of Computational Physics, 2008) to deformable soft tissue by coupling our incompressible Navier-Stokes solver for fluids with a non-linear large deformation finite element method for soft tissue. We use Fung-type constitutive law for the soft tissue that can capture the stress-strain behavior of the tissue. The FSI solver adopts a strongly-coupled partitioned approach that is stabilized with under-relaxation and Aitken acceleration technique. We validate our solvers against the experimental data for tissue valves and elastic tubes. We show the capabilities of our solver by simulating the fluid-structure interaction of tissue valves implanted in the aortic positions and elastic collapsible tubes. This work was partly supported by the Center for Computational Research at the University at Buffalo.

  12. Modeling and Simulation of Variable Mass, Flexible Structures

    NASA Technical Reports Server (NTRS)

    Tobbe, Patrick A.; Matras, Alex L.; Wilson, Heath E.

    2009-01-01

    distribution of mass in the fuel tank or Solid Rocket Booster (SRB) case for various propellant levels. Based on the mass consumed by the liquid engine or SRB, the appropriate propellant model is coupled with the dry structure model for the stage. Then using vehicle configuration data, the integrated vehicle model is assembled and operated on by the constant system shape functions. The system mode shapes and frequencies can then be computed from the resulting generalized mass and stiffness matrices for that mass configuration. The rigid body mass properties of the vehicle are derived from the integrated vehicle model. The coupling terms between the vehicle rigid body motion and elastic deformation are also updated from the constant system shape functions and the integrated vehicle model. This approach was first used to analyze variable mass spinning beams and then prototyped into a generic dynamics simulation engine. The resulting code was tested against Crew Launch Vehicle (CLV-)class problems worked in the TREETOPS simulation package and by Wilson [2]. The Ares I System Integration Laboratory (SIL) is currently being developed at the Marshall Space Flight Center (MSFC) to test vehicle avionics hardware and software in a hardware-in-the-loop (HWIL) environment and certify that the integrated system is prepared for flight. The Ares I SIL utilizes the Ares Real-Time Environment for Modeling, Integration, and Simulation (ARTEMIS) tool to simulate the launch vehicle and stimulate avionics hardware. Due to the presence of vehicle control system filters and the thrust oscillation suppression system, which are tuned to the structural characteristics of the vehicle, ARTEMIS must incorporate accurate structural models of the Ares I launch vehicle. The ARTEMIS core dynamics simulation models the highly coupled nature of the vehicle flexible body dynamics, propellant slosh, and vehicle nozzle inertia effects combined with mass and flexible body properties that vary significant with time

  13. The shell model as a unified view of nuclear structure

    SciTech Connect

    Caurier, E.; Martinez-Pinedo, G.; Nowacki, F.; Poves, A.; Zuker, A.P.

    2005-04-01

    The last decade has witnessed both quantitative and qualitative progress in shell-model studies, which have resulted in remarkable gains in our understanding of the structure of the nucleus. Indeed, it is now possible to diagonalize matrices in determinantal spaces of dimensionality up to 10{sup 9} using the Lanczos tridiagonal construction, whose formal and numerical aspects are analyzed in this review. In addition, many new approximation methods have been developed in order to overcome the dimensionality limitations. New effective nucleon-nucleon interactions have been constructed that contain both two- and three-body contributions. The former are derived from realistic potentials (i.e., potentials consistent with two-nucleon data). The latter incorporate the pure monopole terms necessary to correct the bad saturation and shell-formation properties of the realistic two-body forces. This combination appears to solve a number of hitherto puzzling problems. The present review concentrates on those results which illustrate the global features of the approach: the universality of the effective interaction and the capacity of the shell model to describe simultaneously all the manifestations of the nuclear dynamics, either single-particle or collective in nature. The review also treats in some detail the problems associated with rotational motion, the origin of quenching of the Gamow-Teller transitions, double-{beta} decays, the effect of isospin nonconserving nuclear forces, and the specificities of neutron-rich nuclei. Many other calculations--which appear to have 'merely' spectroscopic interest--are touched upon briefly, although the authors are fully aware that much of the credibility of the shell model rests on them.

  14. The shell model as a unified view of nuclear structure

    NASA Astrophysics Data System (ADS)

    Caurier, E.; Martínez-Pinedo, G.; Nowacki, F.; Poves, A.; Zuker, A. P.

    2005-04-01

    The last decade has witnessed both quantitative and qualitative progress in shell-model studies, which have resulted in remarkable gains in our understanding of the structure of the nucleus. Indeed, it is now possible to diagonalize matrices in determinantal spaces of dimensionality up to 109 using the Lanczos tridiagonal construction, whose formal and numerical aspects are analyzed in this review. In addition, many new approximation methods have been developed in order to overcome the dimensionality limitations. New effective nucleon-nucleon interactions have been constructed that contain both two- and three-body contributions. The former are derived from realistic potentials (i.e., potentials consistent with two-nucleon data). The latter incorporate the pure monopole terms necessary to correct the bad saturation and shell-formation properties of the realistic two-body forces. This combination appears to solve a number of hitherto puzzling problems. The present review concentrates on those results which illustrate the global features of the approach: the universality of the effective interaction and the capacity of the shell model to describe simultaneously all the manifestations of the nuclear dynamics, either single-particle or collective in nature. The review also treats in some detail the problems associated with rotational motion, the origin of quenching of the Gamow-Teller transitions, double- β decays, the effect of isospin nonconserving nuclear forces, and the specificities of neutron-rich nuclei. Many other calculations—which appear to have “merely” spectroscopic interest—are touched upon briefly, although the authors are fully aware that much of the credibility of the shell model rests on them.

  15. Flight test techniques for validating simulated nuclear electromagnetic pulse aircraft responses

    NASA Technical Reports Server (NTRS)

    Winebarger, R. M.; Neely, W. R., Jr.

    1984-01-01

    An attempt has been made to determine the effects of nuclear EM pulses (NEMPs) on aircraft systems, using a highly instrumented NASA F-106B to document the simulated NEMP environment at the Kirtland Air Force Base's Vertically Polarized Dipole test facility. Several test positions were selected so that aircraft orientation relative to the test facility would be the same in flight as when on the stationary dielectric stand, in order to validate the dielectric stand's use in flight configuration simulations. Attention is given to the flight test portions of the documentation program.

  16. Dependence of simulated positron emitter yields in ion beam cancer therapy on modeling nuclear fragmentation.

    PubMed

    Lühr, Armin; Priegnitz, Marlen; Fiedler, Fine; Sobolevsky, Nikolai; Bassler, Niels

    2014-01-01

    In ion beam cancer therapy, range verification in patients using positron emission tomography (PET) requires the comparison of measured with simulated positron emitter yields. We found that (1) changes in modeling nuclear interactions strongly affected the positron emitter yields and that (2) Monte Carlo simulations with SHIELD-HIT10Areasonably matched the most abundant PET isotopes (11)C and (15)O. We observed an ion-energy (i.e., depth) dependence of the agreement between SHIELD-HIT10Aand measurement. Improved modeling requires more accurate measurements of cross-section values. PMID:23352823

  17. Simulation of differential die-away instrument’s response to asymmetrically burned spent nuclear fuel

    SciTech Connect

    Martinik, Tomas; Henzl, Vladimir; Grape, Sophie; Svard, Staffan Jacobsson; Jansson, Peter; Swinhoe, Martyn T.; Tobin, Stephen J.

    2015-03-04

    Here, previous simulation studies of Differential Die–Away (DDA) instrument’s response to active interrogation of spent nuclear fuel from a pressurized water reactor (PWR) yielded promising results in terms of its capability to accurately measure or estimate basic spent fuel assembly (SFA) characteristics, such as multiplication, initial enrichment (IE) and burn-up (BU) as well as the total plutonium content. These studies were however performed only for a subset of idealized SFAs with a symmetric BU with respect to its longitudinal axis. Therefore, to complement the previous results, additional simulations have been performed of the DDA instrument’s response to interrogation of asymmetrically burned spent nuclear fuel in order to determine whether detailed assay of SFAs from all 4 sides will be necessary in real life applications or whether a cost and time saving single sided assay could be used to achieve results of similar quality as previously reported in case of symmetrically burned SFAs.

  18. Simulation of the dispersion of nuclear contamination using an adaptive Eulerian grid model.

    PubMed

    Lagzi, I; Kármán, D; Turányi, T; Tomlin, A S; Haszpra, L

    2004-01-01

    Application of an Eulerian model using layered adaptive unstructured grids coupled to a meso-scale meteorological model is presented for modelling the dispersion of nuclear contamination following the accidental release from a single but strong source to the atmosphere. The model automatically places a finer resolution grid, adaptively in time, in regions were high spatial numerical error is expected. The high-resolution grid region follows the movement of the contaminated air over time. Using this method, grid resolutions of the order of 6 km can be achieved in a computationally effective way. The concept is illustrated by the simulation of hypothetical nuclear accidents at the Paks NPP, in Central Hungary. The paper demonstrates that the adaptive model can achieve accuracy comparable to that of a high-resolution Eulerian model using significantly less grid points and computer simulation time. PMID:15149762

  19. Some results of a simulated test for administration of activity in nuclear medicine.

    PubMed

    Oropesa, P; Hernández, A T; Serra, R A; Varela, C; Woods, M J

    2006-04-01

    This paper describes the results obtained using a simulated test for administration of activity in nuclear medicine between 2002 and 2004. Measurements in the radionuclide calibrator are made during the different stages of the procedure. The test attempts to obtain supplementary information on the quality of the measurement, with the aim of evaluating in a more complete way the accuracy of the administered activity value compared with the prescribed one. The participants' performance has been assessed by means of a statistical analysis of the reported data. Dependences between several attributes of the simulated administration tests results are discussed. Specifically, the proportion of satisfactory results in the 2003-2004 period was found to be higher than in 2002. It reveals an improvement of the activity administration in the Cuban nuclear medicine departments since 2003. PMID:16303312

  20. Evaluation of Recent Upgrades to the NESS (Nuclear Engine System Simulation) Code

    NASA Technical Reports Server (NTRS)

    Fittje, James E.; Schnitzler, Bruce G.

    2008-01-01

    The Nuclear Thermal Rocket (NTR) concept is being evaluated as a potential propulsion technology for exploratory expeditions to the moon, Mars, and beyond. The need for exceptional propulsion system performance in these missions has been documented in numerous studies, and was the primary focus of a considerable effort undertaken during the Rover/NERVA program from 1955 to 1973. The NASA Glenn Research Center is leveraging this past NTR investment in their vehicle concepts and mission analysis studies with the aid of the Nuclear Engine System Simulation (NESS) code. This paper presents the additional capabilities and upgrades made to this code in order to perform higher fidelity NTR propulsion system analysis and design, and a comparison of its results to the Small Nuclear Rocket Engine (SNRE) design.

  1. Nuclear subsurface explosion modeling and hydrodynamic fragmentation simulation of hazardous asteroids

    NASA Astrophysics Data System (ADS)

    Premaratne, Pavithra Dhanuka

    Disruption and fragmentation of an asteroid using nuclear explosive devices (NEDs) is a highly complex yet a practical solution to mitigating the impact threat of asteroids with short warning time. A Hypervelocity Asteroid Intercept Vehicle (HAIV) concept, developed at the Asteroid Deflection Research Center (ADRC), consists of a primary vehicle that acts as kinetic impactor and a secondary vehicle that houses NEDs. The kinetic impactor (lead vehicle) strikes the asteroid creating a crater. The secondary vehicle will immediately enter the crater and detonate its nuclear payload creating a blast wave powerful enough to fragment the asteroid. The nuclear subsurface explosion modeling and hydrodynamic simulation has been a challenging research goal that paves the way an array of mission critical information. A mesh-free hydrodynamic simulation method, Smoothed Particle Hydrodynamics (SPH) was utilized to obtain both qualitative and quantitative solutions for explosion efficiency. Commercial fluid dynamics packages such as AUTODYN along with the in-house GPU accelerated SPH algorithms were used to validate and optimize high-energy explosion dynamics for a variety of test cases. Energy coupling from the NED to the target body was also examined to determine the effectiveness of nuclear subsurface explosions. Success of a disruption mission also depends on the survivability of the nuclear payload when the secondary vehicle approaches the newly formed crater at a velocity of 10 km/s or higher. The vehicle may come into contact with debris ejecting the crater which required the conceptual development of a Whipple shield. As the vehicle closes on the crater, its skin may also experience extreme temperatures due to heat radiated from the crater bottom. In order to address this thermal problem, a simple metallic thermal shield design was implemented utilizing a radiative heat transfer algorithm and nodal solutions obtained from hydrodynamic simulations.

  2. Simulation and modeling techniques for parachute fluid-structure interactions

    NASA Astrophysics Data System (ADS)

    Stein, Keith Robert

    This thesis is on advanced flow simulation and modeling techniques for fluid-structure interactions (FSI) encountered in parachute systems. The main fluid dynamics solver is based on the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) finite element formulation of the Navier-Stokes equations of incompressible flows. The DSD/SST formulation, which was introduced earlier for flow computations involving moving boundaries and interfaces, gives us the capability to handle parachute structural deformations. The structural dynamics solver is based on a total Lagrangian finite element formulation of the equilibrium equations for a "tension structure" composed of membranes, cables, and concentrated masses. The fluid and structure are coupled iteratively within a nonlinear iteration loop, with multiple nonlinear iterations improving the convergence of the coupled system. Unstructured mesh generation and mesh moving techniques for handling of parachute deformations are developed and/or adapted to address the challenges posed by the coupled problem. The FSI methodology was originally implemented on the Thinking Machines CM-5 supercomputer and is now actively used on the CRAY T3E-1200. Applications to a variety of round and cross parachutes used by the US Army are presented, and different stages of the parachute operations, including inflation and terminal descent, are modeled.

  3. Probabilistic Simulation of the Human Factor in Structural Reliability

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Singhal, Surendra N.

    1994-01-01

    The formal approach described herein computationally simulates the probable ranges of uncertainties for the human factor in probabilistic assessments of structural reliability. Human factors such as marital status, professional status, home life, job satisfaction, work load, and health are studied by using a multifactor interaction equation (MFIE) model to demonstrate the approach. Parametric studies in conjunction with judgment are used to select reasonable values for the participating factors (primitive variables). Subsequently performed probabilistic sensitivity studies assess the suitability of the MFIE as well as the validity of the whole approach. Results show that uncertainties range from 5 to 30 percent for the most optimistic case, assuming 100 percent for no error (perfect performance).

  4. Probabilistic simulation of the human factor in structural reliability

    NASA Astrophysics Data System (ADS)

    Chamis, Christos C.; Singhal, Surendra N.

    1994-09-01

    The formal approach described herein computationally simulates the probable ranges of uncertainties for the human factor in probabilistic assessments of structural reliability. Human factors such as marital status, professional status, home life, job satisfaction, work load, and health are studied by using a multifactor interaction equation (MFIE) model to demonstrate the approach. Parametric studies in conjunction with judgment are used to select reasonable values for the participating factors (primitive variables). Subsequently performed probabilistic sensitivity studies assess the suitability of the MFIE as well as the validity of the whole approach. Results show that uncertainties range from 5 to 30 percent for the most optimistic case, assuming 100 percent for no error (perfect performance).

  5. Phase structure of a single urban intersection: a simulation study

    NASA Astrophysics Data System (ADS)

    Ebrahim Foulaadvand, M.; Fukui, M.; Belbasi, S.

    2010-07-01

    We study the phase structure of a cellular automata model proposed by Belbasi and Foulaadvand to describe the vehicular traffic flow at the intersection of two perpendicular streets. A set of traffic lights operating in a fixed-time scheme controls the traffic flow. A closed boundary condition is applied to the streets, each of which conducts a unidirectional flow. Streets are single-lane and cars cannot turn upon reaching the intersection. Via extensive Monte Carlo simulations it is shown that the model phase diagram consists of ten phases. The flow characteristics in each phase are investigated and the types of phase transitions between phases are specified.

  6. Simulation analysis for ion assisted fast ignition using structured targets

    NASA Astrophysics Data System (ADS)

    Sakagami, H.; Johzaki, T.; Sunahara, A.; Nagatomo, H.

    2016-05-01

    As the heating efficiency by fast electrons in the fast ignition scheme is estimated to be very low due to their large divergence angle and high energy. To mitigate this problem, low-density plastic foam, which can generate not only proton (H+) but also carbon (C6+) beams, can be introduced to currently used cone-guided targets and additional core heating by ions is expected. According to 2D PIC simulations, it is found that the ion beams also diverge by the static electric field and concave surface deformation. Thus structured targets are suggested to optimize ion beam characteristics, and their improvement and core heating enhancement by ion beams are confirmed.

  7. Simulation of the CLIC transfer structure by means of MAFIA

    NASA Astrophysics Data System (ADS)

    Millich, Antonio

    1993-12-01

    The function of the CTS is to extract 30 GHz power from the drive beam and to make it available for the acceleration of the main beam. The simulation of a six cells section of the CTS using the MAFIA set of codes has provided the designers of the structure with a set of RF parameters at 30 GHz. The frequency domain analysis has allowed the plotting of the dispersion curves for the first few pass bands, whereas the time domain analysis has provided results on the shape and magnitude of the longitudinal and transverse wake fields and of the loss factors.

  8. Growth Simulation and Structure Analysis of Obliquely Deposited Thin Films

    NASA Astrophysics Data System (ADS)

    Belyaev, B. A.; Izotov, A. V.; Solovev, P. N.

    2016-06-01

    Based on the Monte Carlo method, a model of growth of thin films prepared by oblique angle deposition of particles is constructed. The morphology of structures synthesized by simulation is analyzed. To study the character of distribution of microstructural elements (columns) in the film plane, the autocorrelation function of the microstructure and the fast Fourier transform are used. It is shown that with increasing angle of particle incidence, the film density monotonically decreases; in this case, anisotropy arises and monotonically increases in the cross sections of columns, and the anisotropy of distribution of columns in the substrate plane also increases.

  9. An End-To-End Test of A Simulated Nuclear Electric Propulsion System

    NASA Technical Reports Server (NTRS)

    VanDyke, Melissa; Hrbud, Ivana; Goddfellow, Keith; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    The Safe Affordable Fission Engine (SAFE) test series addresses Phase I Space Fission Systems issues in it particular non-nuclear testing and system integration issues leading to the testing and non-nuclear demonstration of a 400-kW fully integrated flight unit. The first part of the SAFE 30 test series demonstrated operation of the simulated nuclear core and heat pipe system. Experimental data acquired in a number of different test scenarios will validate existing computational models, demonstrated system flexibility (fast start-ups, multiple start-ups/shut downs), simulate predictable failure modes and operating environments. The objective of the second part is to demonstrate an integrated propulsion system consisting of a core, conversion system and a thruster where the system converts thermal heat into jet power. This end-to-end system demonstration sets a precedent for ground testing of nuclear electric propulsion systems. The paper describes the SAFE 30 end-to-end system demonstration and its subsystems.

  10. A Poisson resampling method for simulating reduced counts in nuclear medicine images

    NASA Astrophysics Data System (ADS)

    White, Duncan; Lawson, Richard S.

    2015-05-01

    Nuclear medicine computers now commonly offer resolution recovery and other software techniques which have been developed to improve image quality for images with low counts. These techniques potentially mean that these images can give equivalent clinical information to a full-count image. Reducing the number of counts in nuclear medicine images has the benefits of either allowing reduced activity to be administered or reducing acquisition times. However, because acquisition and processing parameters vary, each user should ideally evaluate the use of images with reduced counts within their own department, and this is best done by simulating reduced-count images from the original data. Reducing the counts in an image by division and rounding off to the nearest integer value, even if additional Poisson noise is added, is inadequate because it gives incorrect counting statistics. This technical note describes how, by applying Poisson resampling to the original raw data, simulated reduced-count images can be obtained while maintaining appropriate counting statistics. The authors have developed manufacturer independent software that can retrospectively generate simulated data with reduced counts from any acquired nuclear medicine image.

  11. The Structural Underpinnings of Policy Learning: A Classroom Policy Simulation

    NASA Astrophysics Data System (ADS)

    Bird, Stephen

    This paper investigates the relationship between the centrality of individual actors in a social network structure and their policy learning performance. In a dynamic comparable to real-world policy networks, results from a classroom simulation demonstrate a strong relationship between centrality in social learning networks and grade performance. Previous research indicates that social network centrality should have a positive effect on learning in other contexts and this link is tested in a policy learning context. Second, the distinction between collaborative learning versus information diffusion processes in policy learning is examined. Third, frequency of interaction is analyzed to determine whether consistent, frequent tics have a greater impact on the learning process. Finally, the data arc analyzed to determine if the benefits of centrality have limitations or thresholds when benefits no longer accrue. These results demonstrate the importance of network structure, and support a collaborative conceptualization of the policy learning process.

  12. Probabilistic simulation of the human factor in structural reliability

    NASA Technical Reports Server (NTRS)

    Shah, Ashwin R.; Chamis, Christos C.

    1991-01-01

    Many structural failures have occasionally been attributed to human factors in engineering design, analyses maintenance, and fabrication processes. Every facet of the engineering process is heavily governed by human factors and the degree of uncertainty associated with them. Factors such as societal, physical, professional, psychological, and many others introduce uncertainties that significantly influence the reliability of human performance. Quantifying human factors and associated uncertainties in structural reliability require: (1) identification of the fundamental factors that influence human performance, and (2) models to describe the interaction of these factors. An approach is being developed to quantify the uncertainties associated with the human performance. This approach consists of a multi factor model in conjunction with direct Monte-Carlo simulation.

  13. Seismic Source Characteristics of Nuclear and Chemical Explosions in Granite from Hydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Xu, Heming; Rodgers, Arthur J.; Lomov, Ilya N.; Vorobiev, Oleg Y.

    2014-03-01

    Seismic source characteristics of low-yield (0.5-5 kt) underground explosions are inferred from hydrodynamic simulations using a granite material model on high-performance (parallel) computers. We use a non-linear rheological model for granite calibrated to historical near-field nuclear test data. Equivalent elastic P-wave source spectra are derived from the simulated hydrodynamic response using reduced velocity potentials. Source spectra and parameters are compared with the models of M ueller and M urphy (Bull Seism Soc Am 61:1675-1692, 1971, hereafter MM71) and D enny and J ohnson (Explosion source phenomenology, pp 1-24, 1991, hereafter DJ91). The source spectra inferred from the simulations of different yields at normal scaled depth-of-burial (SDOB) match the MM71 spectra reasonably well. For normally buried nuclear explosions, seismic moments are larger for the hydrodynamic simulations than MM71 (by 25 %) and for DJ91 (by over a factor of 2), however, the scaling of moment with yield across this low-yield range is consistent for our calculations and the two models. Spectra from our simulations show higher corner frequencies at the lower end of the 0.5-5.0 kt yield range and stronger variation with yield than the MM71 and DJ91 models predict. The spectra from our simulations have additional energy above the corner frequency, probably related to non-linear near-source effects, but at high frequencies the spectral slopes agree with the f -2 predictions of MM71. Simulations of nuclear explosions for a range of SDOB from 0.5 to 3.9 show stronger variations in the seismic moment than predicted by the MM71 and DJ91 models. Chemical explosions are found to generate higher moments by a factor of about two compared to nuclear explosions of the same yield in granite and at normal depth-of-burial, broadly consistent with comparisons of nuclear and chemical shots at the US Nevada Test Site (D enny, Proceeding of symposium on the non-proliferation experiment, Rockville

  14. The Structural Role of Zr within Alkali Borosilicate Glasses for Nuclear Waste Immobilisation

    SciTech Connect

    A Connelly; N Hyatt; K Travis; R Hand; E Maddrell; R Short

    2011-12-31

    Zirconium is a key constituent element of High Level nuclear Waste (HLW) glasses, occurring both as a fission product and a fuel cladding component. As part of a wider research program aimed at optimizing the solubility of zirconium in HLW glasses, we have investigated the structural chemistry of zirconium in such materials using X-ray Absorption Spectroscopy (XAS). Zirconium K-edge XAS data were acquired from several inactive simulant and simplified waste glass compositions, including a specimen of blended Magnox/UO{sub 2} fuel waste glass. These data demonstrate that zirconium is immobilized as (octahedral) six-fold coordinate ZrO{sub 6} species in these glasses, with a Zr-O contact distance of 2.09 {angstrom}. The next nearest neighbors of the Zr species are Si at 3.42 {angstrom} and possibly Na at 3.44 {angstrom}, no next nearest neighbor Zr could be resolved.

  15. DISCOS- DYNAMIC INTERACTION SIMULATION OF CONTROLS AND STRUCTURES (IBM VERSION)

    NASA Technical Reports Server (NTRS)

    Frisch, H. P.

    1994-01-01

    The Dynamic Interaction Simulation of Controls and Structure (DISCOS) program was developed for the dynamic simulation and stability analysis of passive and actively controlled spacecraft. In the use of DISCOS, the physical system undergoing analysis may be generally described as a cluster of contiguous flexible structures (bodies) that comprise a mechanical system, such as a spacecraft. The entire system (spacecraft) or portions thereof may be either spinning or nonspinning. Member bodies of the system may undergo large relative excursions, such as those of appendage deployment or rotor/ stator motion. The general system of bodies is, by its inherent nature, a feedback system in which inertial forces (such as those due to centrifugal and Coriolis acceleration) and the restoring and damping forces are motion-dependent. The system may possess a control system in which certain position and rate errors are actively controlled through the use of reaction control jets, servomotors, or momentum wheels. Bodies of the system may be interconnected by linear or nonlinear springs and dampers, by a gimbal and slider block mechanism, or by any combination of these. The DISCOS program can be used to obtain nonlinear and linearized time response of the system, interaction constant forces in the system, total system resonance properties, and frequency domain response and stability information for the system. DISCOS is probably the most powerful computational tool to date for the computer simulation of actively controlled coupled multi-flexible-body systems. The program is not easy to understand and effectively apply, but is not intended for simple problems. The DISCOS user is expected to have extensive working knowledge of rigid-body and flexible-body dynamics, finite-element techniques, numerical methods, and frequency-domain analysis. Various applications of DISCOS include simulation of the Shuttle payload deployment/retrieval mechanism, solar panel array deployment, antenna

  16. LOOS: an extensible platform for the structural analysis of simulations.

    PubMed

    Romo, Tod D; Grossfield, Alan

    2009-01-01

    We have developed LOOS (Lightweight Object-Oriented Structure-analysis library) as an object-oriented library designed to facilitate the rapid development of tools for the structural analysis of simulations. LOOS supports the native file formats of most common simulation packages including AMBER, CHARMM, CNS, Gromacs, NAMD, Tinker, and X-PLOR. Encapsulation and polymorphism are used to simultaneously provide a stable interface to the programmer and make LOOS easily extensible. A rich atom selection language based on the C expression syntax is included as part of the library. LOOS enables students and casual programmer-scientists to rapidly write their own analytical tools in a compact and expressive manner resembling scripting. LOOS is written in C++ and makes extensive use of the Standard Template Library and Boost, and is freely available under the GNU General Public License (version 3) LOOS has been tested on Linux and MacOS X, but is written to be portable and should work on most Unix-based platforms. PMID:19965179

  17. Visualizing microscopic structure of simulated model basalt melt

    NASA Astrophysics Data System (ADS)

    Bohara, Bidur; Karki, Bijaya B.

    2013-08-01

    We perform a detailed visualization-based analysis of atomic-position series data for model basalt melt obtained from first-principles (quantum mechanical) molecular dynamics simulations. To gain insight into the short- and mid-range order of the melt structure, we extract and visualize the details of radial distribution function (RDF) and coordination environment. The first peaks of all partial RDFs lie in the distance range of 1.6-4 Å and the corresponding mean coordination numbers vary from less than 1 to more than 9. The coordination environments involving cations and anions differ substantially from each other, each consisting of a rich set of coordination states. These states vary both spatially and temporally: The per-atom coordination information extracted on the fly is rendered instantaneously as the spheres and polyhedra as well as along the corresponding trajectories using a color-coding scheme. The information is also visualized as clusters formed by atoms that are coordinated at different time intervals during the entire simulation. The Si-O coordination is comprised of almost all tetrahedra (4-fold) whereas the Al-O coordination includes both tetrahedra (4-fold) and pentahedra (5-fold). The animated visualization suggests that the melt structure can be viewed as a dynamic (partial) network of Al/Si-O coordination polyhedra connected via bridging oxygen in an inhomogeneous distribution of mobile magnesium and calcium atoms.

  18. Simulation of population growth and structure of the population

    NASA Astrophysics Data System (ADS)

    Maksymowicz, A. Z.

    2002-08-01

    A computer study of population growth and biological ageing in the Penna model is presented. The stress is put on the analysis of the age structure and the distribution of 'bad' mutations m in the population. Results of computer simulation are compared with the simplest logistic model approach which ignores genetic contribution to the life game and accounts only for death due to limited environmental capacity, the Verhulst factor. The Penna model accounts also for genetic load and results of the simulation show that the final population essentially consists of the fittest individuals, as is expected. A more detailed analysis of the genome structure Δ( m) discloses significant marks of the history. The main conclusions are: (a) there is a clear correlation between population n, age a and the number m of bad mutations and (b) there is no correlation between particular configurations Δ( m) of genomes of the same m and the fraction of the population of this characteristics Δ( m). A typical run takes a couple of hours on an HP EXEMPLAR machine, and for a population of about n=10 6.

  19. Operational safety enhancement of Soviet-designed nuclear reactors via development of nuclear power plant simulators and transfer of related technology

    SciTech Connect

    Kohut, P.; Epel, L.G.; Tutu, N.K.

    1998-08-01

    The US Department of Energy (DOE), under the US government`s International Nuclear Safety Program (INSP), is implementing a program of developing and providing simulators for many of the Russian and Ukrainian Nuclear Power Plants (NPPs). Pacific Northwest National Laboratory (PNNL) and Brookhaven National Laboratory (BNL) manage and provide technical oversight of the various INSP simulator projects for DOE. The program also includes a simulator technology transfer process to simulator design organizations in Russia and Ukraine. Training programs, installation of new simulators, and enhancements in existing simulators are viewed as providing a relatively fast and cost-effective technology transfer that will result in measurable improvement in the safety culture and operation of NPPs. A review of this program, its present status, and its accomplishments are provided in this paper.

  20. Solution Structures of Rat Amylin Peptide: Simulation, Theory, and Experiment

    PubMed Central

    Reddy, Allam S.; Wang, Lu; Lin, Yu-Shan; Ling, Yun; Chopra, Manan; Zanni, Martin T.; Skinner, James L.; De Pablo, Juan J.

    2010-01-01

    Abstract Amyloid deposits of amylin in the pancreas are an important characteristic feature found in patients with Type-2 diabetes. The aggregate has been considered important in the disease pathology and has been studied extensively. However, the secondary structures of the individual peptide have not been clearly identified. In this work, we present detailed solution structures of rat amylin using a combination of Monte Carlo and molecular dynamics simulations. A new Monte Carlo method is presented to determine the free energy of distinct biomolecular conformations. Both folded and random-coil conformations of rat amylin are observed in water and their relative stability is examined in detail. The former contains an α-helical segment comprised of residues 7–17. We find that at room temperature the folded structure is more stable, whereas at higher temperatures the random-coil structure predominates. From the configurations and weights we calculate the α-carbon NMR chemical shifts, with results that are in reasonable agreement with experiments of others. We also calculate the infrared spectrum in the amide I stretch regime, and the results are in fair agreement with the experimental line shape presented herein. PMID:20141758

  1. Maintain rigid structures in Verlet based Cartesian molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Tao, Peng; Wu, Xiongwu; Brooks, Bernard R.

    2012-10-01

    An algorithm is presented to maintain rigid structures in Verlet based Cartesian molecular dynamics (MD) simulations. After each unconstrained MD step, the coordinates of selected particles are corrected to maintain rigid structures through an iterative procedure of rotation matrix computation. This algorithm, named as SHAPE and implemented in CHARMM program suite, avoids the calculations of Lagrange multipliers, so that the complexity of computation does not increase with the number of particles in a rigid structure. The implementation of this algorithm does not require significant modification of propagation integrator, and can be plugged into any Cartesian based MD integration scheme. A unique feature of the SHAPE method is that it is interchangeable with SHAKE for any object that can be constrained as a rigid structure using multiple SHAKE constraints. Unlike SHAKE, the SHAPE method can be applied to large linear (with three or more centers) and planar (with four or more centers) rigid bodies. Numerical tests with four model systems including two proteins demonstrate that the accuracy and reliability of the SHAPE method are comparable to the SHAKE method, but with much more applicability and efficiency.

  2. Concurrent Probabilistic Simulation of High Temperature Composite Structural Response

    NASA Technical Reports Server (NTRS)

    Abdi, Frank

    1996-01-01

    A computational structural/material analysis and design tool which would meet industry's future demand for expedience and reduced cost is presented. This unique software 'GENOA' is dedicated to parallel and high speed analysis to perform probabilistic evaluation of high temperature composite response of aerospace systems. The development is based on detailed integration and modification of diverse fields of specialized analysis techniques and mathematical models to combine their latest innovative capabilities into a commercially viable software package. The technique is specifically designed to exploit the availability of processors to perform computationally intense probabilistic analysis assessing uncertainties in structural reliability analysis and composite micromechanics. The primary objectives which were achieved in performing the development were: (1) Utilization of the power of parallel processing and static/dynamic load balancing optimization to make the complex simulation of structure, material and processing of high temperature composite affordable; (2) Computational integration and synchronization of probabilistic mathematics, structural/material mechanics and parallel computing; (3) Implementation of an innovative multi-level domain decomposition technique to identify the inherent parallelism, and increasing convergence rates through high- and low-level processor assignment; (4) Creating the framework for Portable Paralleled architecture for the machine independent Multi Instruction Multi Data, (MIMD), Single Instruction Multi Data (SIMD), hybrid and distributed workstation type of computers; and (5) Market evaluation. The results of Phase-2 effort provides a good basis for continuation and warrants Phase-3 government, and industry partnership.

  3. Computational simulation of acoustic fatigue for hot composite structures

    NASA Technical Reports Server (NTRS)

    Singhal, Surendra N.; Murthy, Pappu L. N.; Chamis, Christos C.; Nagpal, Vinod K.; Sutjahjo, Edhi

    1991-01-01

    Predictive methods/computer codes for the computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component are discussed. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of acoustic noise generated from a vibrating component, degradation in material properties of a composite laminate at use temperature, dynamic response of acoustically excited hot multilayered composite structure, degradation in the first ply strength of the excited structure due to acoustic loading, and acoustic fatigue resistance of the excited structure, including the propulsion environment. Effects of the laminate lay-up and environment on the acoustic fatigue life are evaluated. The results show that, by keeping the angled plies on the outer surface of the laminate, a substantial increase in the acoustic fatigue life is obtained. The effect of environment (temperature and moisture) is to relieve the residual stresses leading to an increase in the acoustic fatigue life of the excited panel.

  4. Computational simulation of acoustic fatigue for hot composite structures

    NASA Technical Reports Server (NTRS)

    Singhal, S. N.; Nagpal, V. K.; Murthy, P. L. N.; Chamis, C. C.

    1991-01-01

    This paper presents predictive methods/codes for computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of (1) acoustic noise generated from a vibrating component, (2) degradation in material properties of the composite laminate at use temperature, (3) dynamic response of acoustically excited hot multilayered composite structure, (4) degradation in the first-ply strength of the excited structure due to acoustic loading, and (5) acoustic fatigue resistance of the excited structure, including propulsion environment. Effects of the laminate lay-up and environment on the acoustic fatigue life are evaluated. The results show that, by keeping the angled plies on the outer surface of the laminate, a substantial increase in the acoustic fatigue life is obtained. The effect of environment (temperature and moisure) is to relieve the residual stresses leading to an increase in the acoustic fatigue life of the excited panel.

  5. Nuclear structure and reactions in the fermionic molecular dynamics approach

    NASA Astrophysics Data System (ADS)

    Neff, T.; Feldmeier, H.

    2008-05-01

    The Fermionic Molecular Dynamics (FMD) model uses Gaussian wave packets as single-particle states. Intrinsic many-body basis states are constructed as Slater determinants which have to be projected on parity, angular momentum and total linear momentum to restore the symmetries of the Hamiltonian. The flexibility of the Gaussian basis allows to economically describe states with shell structures as well as states featuring clustering or halos. We use an effective interaction that is derived from the realistic Argonne V18 interaction by means of the Unitary Correlation Operator Method (UCOM). A phenomenological momentum-dependent two-body correction simulates contributions from missing three-body forces and three-body correlations. We discuss 12C with a special emphasis on the structure of the excited 0+ and 2+ states. We analyze the degree of α-clustering and confirm, taking inelastic electron scattering data into account, the conjecture that the Hoyle state has to be understood as a loosely bound system of alpha particles. We will also present first results on the application of FMD for the calculation of scattering phase shifts in 3He — 4He.

  6. Are there nuclear structure effects on the isoscalar giant monopole resonance and nuclear incompressibility near A ∼ 90?

    NASA Astrophysics Data System (ADS)

    Gupta, Y. K.; Garg, U.; Howard, K. B.; Matta, J. T.; Şenyiğit, M.; Itoh, M.; Ando, S.; Aoki, T.; Uchiyama, A.; Adachi, S.; Fujiwara, M.; Iwamoto, C.; Tamii, A.; Akimune, H.; Kadono, C.; Matsuda, Y.; Nakahara, T.; Furuno, T.; Kawabata, T.; Tsumura, M.; Harakeh, M. N.; Kalantar-Nayestanaki, N.

    2016-09-01

    "Background-free" spectra of inelastic α-particle scattering have been measured at a beam energy of 385 MeV in 90,92Zr and 92Mo at extremely forward angles, including 0°. The ISGMR strength distributions for the three nuclei coincide with each other, establishing clearly that nuclear incompressibility is not influenced by nuclear shell structure near A ∼ 90 as was claimed in recent measurements.

  7. Massively Parallel Simulations of Diffusion in Dense Polymeric Structures

    SciTech Connect

    Faulon, Jean-Loup, Wilcox, R.T. , Hobbs, J.D. , Ford, D.M.

    1997-11-01

    An original computational technique to generate close-to-equilibrium dense polymeric structures is proposed. Diffusion of small gases are studied on the equilibrated structures using massively parallel molecular dynamics simulations running on the Intel Teraflops (9216 Pentium Pro processors) and Intel Paragon(1840 processors). Compared to the current state-of-the-art equilibration methods this new technique appears to be faster by some orders of magnitude.The main advantage of the technique is that one can circumvent the bottlenecks in configuration space that inhibit relaxation in molecular dynamics simulations. The technique is based on the fact that tetravalent atoms (such as carbon and silicon) fit in the center of a regular tetrahedron and that regular tetrahedrons can be used to mesh the three-dimensional space. Thus, the problem of polymer equilibration described by continuous equations in molecular dynamics is reduced to a discrete problem where solutions are approximated by simple algorithms. Practical modeling applications include the constructing of butyl rubber and ethylene-propylene-dimer-monomer (EPDM) models for oxygen and water diffusion calculations. Butyl and EPDM are used in O-ring systems and serve as sealing joints in many manufactured objects. Diffusion coefficients of small gases have been measured experimentally on both polymeric systems, and in general the diffusion coefficients in EPDM are an order of magnitude larger than in butyl. In order to better understand the diffusion phenomena, 10, 000 atoms models were generated and equilibrated for butyl and EPDM. The models were submitted to a massively parallel molecular dynamics simulation to monitor the trajectories of the diffusing species.

  8. NGC 1068 - Resolution of nuclear structure in the optical continuum

    NASA Technical Reports Server (NTRS)

    Lynds, Roger; Faber, S. M.; Light, Robert M.; Groth, Edward J.; Holtzman, Jon A.

    1991-01-01

    The HST Planetary Camera has been used to obtain an optical continuum image of the Seyfert galaxy NGC 1068. The image reveals a bright nucleus embedded in an irregular cloudlike structure which is well-differentiated against the background of the galaxy. The nucleus is resolved, with an FWHM of about 0.15 arcsec, or 11 pc. There is no evidence for any unresolved nuclear component. The precise geometry of the scattering region cannot yet be inferred. The cloud surrounding the nucleus is elongated in the NE-SSW direction and has extreme dimensions of 3.5 arcsec x 1.7 arcsec. The brightness centroid is situated 0.4 arcsec SW of the nucleus. It is concluded that the light from the cloud is contributed largely by stars, but that the appearance of the cloud is distinctly dissimilar to what is expected from young or old stellar systems and bears to simple relationship to the numerous features that have heretofore been resolved at other wavelengths.

  9. Geographic structure of European anchovy: A nuclear-DNA study

    NASA Astrophysics Data System (ADS)

    Bouchenak-Khelladi, Yanis; Durand, Jean-Dominique; Magoulas, Antonios; Borsa, Philippe

    2008-08-01

    Atlantic-Mediterranean anchovies were genetically characterized at two polymorphic nuclear loci (intron 6 of two creatine-kinase genes) and compared to reference Engraulis albidus and E. encrasicolus samples from the northern Western Mediterranean to provide new insights into their geographic structure. Northeastern Atlantic anchovy, represented by one sample from the Canary archipelago and one sample from the Alboran Sea, were genetically distinct from Mediterranean E. encrasicolus (Weir and Cockerham's ^θ = 0.027-0.311), indicating geographic isolation from either side of the Almería-Oran oceanographic front. Generally smaller genetic differences were evident among anchovy populations from different sub-basins in the Mediterranean ( ^θ = - 0.019-0.116), the genetic differences between Black Sea and Ionian Sea/Aegean Sea anchovies being the strongest ( ^θ = 0.002-0.116). There was no evidence of the presence of E. albidus in our samples outside Camargue (northern shore of the Western Mediterranean). However, a sample from the southern Western Mediterranean appeared to be genetically intermediate between E. albidus and Mediterranean E. encrasicolus, indicating possible hybridization. Anchovy from the Benguela current system off southern Africa possessed allele frequencies characteristic of E. albidus at one locus and Northeastern Atlantic anchovy at the other locus, suggesting past introgression.

  10. Nuclear-structure aspects of double beta decay

    SciTech Connect

    Suhonen, Jouni

    2010-11-24

    Neutrinoless double beta (0{nu}{beta}{beta}) decay of nuclei is a process that requires the neutrino to be a massive Majorana particle and thus cannot proceed in the standard model of electro-weak interactions. Recent results of the neutrino-oscillation experiments have produced accurate information on the mixing of neutrinos and their squared mass differences. The 0{nu}{beta}{beta} decay takes place in atomic nuclei where it can be observed, at least in principle, by underground neutrino experiments. The need of nuclei in observation of the 0{nu}{beta}{beta} decay bears two facets: The nucleus serves as laboratory for detection but at the same time its complicated many-nucleon structure interferes strongly with the analysis of the experimental data. The information about the weak-interaction observables, like the neutrino mass, has to be filtered from the data through the nuclear matrix elements (NMEs). Hence, exact knowledge about the NMEs is of paramount importance in the analysis of the data provided by the expensive and time-consuming underground experiments.

  11. Nuclear structure and reaction studies at medium energies

    SciTech Connect

    Hoffmann, G.W.; Ray, R.L.

    1990-10-01

    This document constitutes the (1988--1991) technical progress report for the ongoing medium energy physics research program supported by the US Department of Energy through special Research Grant FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF), the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL), and at the Fermi National Accelerator Laboratory (FNAL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics;(2) provide unique, first-of-a-kind exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics.

  12. Studies of Nuclear Structure and Decay Properties of Actinide Nuclei

    SciTech Connect

    Kondev, F. G.; Ahmad, I.; Carpenter, M. P.; Chiara, C. J.; Greene, J. P.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Moore, E. F.; Seweryniak, D.; Zhu, S.; Kellett, M. A.; Nichols, A. L.

    2009-01-28

    The identification of single-particle states in heavy actinide nuclei by means of studying their decay schemes plays a seminal role in understanding the structure of the heaviest elements and testing the predictive power of modern theoretical models. The heaviest odd-mass nuclides available in sufficient quantity for detailed decay spectroscopic studies are 20-h {sup 255} Fm(for neutrons) and 20-d {sup 253}Es(for protons). Decay spectra of these isotopes, together with those for the odd-odd 276-d {sup 254}Es nuclide, were measured using a variety of {alpha}-particle and {gamma}-ray spectroscopy techniques. Well-defined decay data are also essential pre-requisites for the detection and accurate characterization of fissile radionuclides. The parameters of greatest relevance include actinide half-lives, branching fractions, and {alpha}-particle and {gamma}-ray energies and emission probabilities. Their quantification to good accuracy provides the means of monitoring their presence, behavior and transport in nuclear facilities as well as any clandestine movement and usage. As a consequence of recommendations made at recent IAEA research coordination meetings on 'Updated Decay Data Library for Actinides,' measurements were undertaken to determine specific decay data of the more inadequately defined radionuclides.

  13. Monitoring the Geneseo Nuclear Structure Lab with VISION

    NASA Astrophysics Data System (ADS)

    Nicklaw, R.; Padalino, S.; McLean, J.

    2002-10-01

    VISION (Virtual Instrument System Information) is a LabVIEW based program designed to monitor a 2 MV Van de Graaff accelerator in the Geneseo Nuclear Structure Laboratory (GNSL). The purpose of the system is to monitor and notify the user of potentially critical situations in the lab. Main parameters of interest are the water coolant temperatures in the diffusion pumps, pressures within the vacuum chambers, and Van de Graaff operational parameters. LabVIEW reads these values and then displays them on monitors located throughout the laboratory. The user can set alarm limits on the relevant parameters, and when exceeded notifies the user verbally and visually. Recent additions to the VISION program include the water level sensor, calibration of the pressure readings, a web server application, and data logging. The VISION system is Internet accessible ^1, data from the main screen is displayed over the web for remote monitoring of the accelerator. Another useful monitoring tool is the data logger, which writes acquired data to a formatted text document at specified intervals. A future goal for VISION is to not only monitor, but to control aspects of the GNSL with LabVIEW. ^1 Webpage accessible at: http://s69n144.sci.geneseo.edu/vision.htm * Research funded in part by the United States Department of Energy

  14. VALIDATION OF TRANSIENT STRUCTURAL DYNAMICS SIMULATIONS: AN EXAMPLE

    SciTech Connect

    J. SCHULTZ; F. HEMEZ; ET AL

    2001-03-01

    The field of computational structural dynamics is on the threshold of revolutionary change. The ever-increasing costs of physical experiments coupled with advances in massively parallel computer architecture are steering the engineering analyst to be more and more reliant on numerical calculations with little to no data available for experimental confirmation. New areas of research in engineering analysis have come about as a result of the changing roles of computations and experiments. Whereas in the past the primary function of physical experiments has been to confirm or ''prove'' the accuracy of a computational simulation, the new environment of engineering is forcing engineers to allocate precious experimental resources differently. Rather than trying to ''prove'' whether a calculation is correct, the focus is on learning how to use experimental data to ''improve'' the accuracy of computational simulations. This process of improving the accuracy of calculations through the use of experimental data is termed ''model validation.'' Model validation emphasizes the need for quantitative techniques of assessing the accuracy of a computational prediction with respect to experimental measurements, taking into account that both the prediction and the measurement have uncertainties associated with them. The ''vugraph norm,'' where one overlays transparencies of simulated data and experimental data in an attempt to show consistency, is no longer an adequate means of demonstrating validity of predictions. To approach this problem, a paradigm from the field of statistical pattern recognition has been adopted [1]. This paradigm generalizes the extraction of corresponding ''features'' from the experimental data and the simulated data, and treats the comparison of these sets of features as a statistical test. The parameters that influence the output of the simulation (such as equation parameters, initial and boundary conditions, etc.) can then be adjusted to minimize the

  15. Numerical simulations and stability of magnetic structures in the heliosheath

    NASA Astrophysics Data System (ADS)

    Cox, S.; Avinash, K.; Shaikh, D.; Zank, G. P.

    2008-12-01

    We extend the three fluid model of Avinash and Zank [2007] for magnetic structures in the heliosheath to a four fluid model consisting of electrons, pick-up ions (PUIs), solar wind ions (SWI), and neutral hydrogen. The PUIs are generated by neutrals via charge exchange with SWI. Since the kinetic pressure of PUIs is nearly three to four times the pressure of SWI, these are more suited to mediate small scale structures in the heliosheath such as magnetic holes/humps etc. The constant energy exchange between these two fluids drives them non-adiabatic. The PUIs are isothermal while SWI are non adiabatic with an index ~1.25. The four fluid model captures these effects via a modified equation of state for PUI and SWI. The phase space of time independent solutions in terms of the Mach numbers of PUI and SWI is constructed to delineate the parameter space which allows structure formation in the heliosheath. We examine the stability of the time independent solutions by evolving them via a full system of Hall -MHD equations. The simulation results show that these solutions are not quite stable. As the structure propagates it develops growing oscillations in the wings. Concomitantly, there are changes in the amplitude and width of the structure. This instability could be due to local changes in the velocity of the structure and reflects an exchange between the kinetic and magnetic parts of the total energy. Our results showing the presence of growing oscillations in the wings of solitary wave solutions are consistent with the recent analysis of magnetic holes in the heliosheth by Burlaga et al [2007].

  16. Results from tight and loose coupled multiphysics in nuclear fuels performance simulations using BISON

    SciTech Connect

    Novascone, S. R.; Spencer, B. W.; Andrs, D.; Williamson, R. L.; Hales, J. D.; Perez, D. M.

    2013-07-01

    The behavior of nuclear fuel in the reactor environment is affected by multiple physics, most notably heat conduction and solid mechanics, which can have a strong influence on each other. To provide credible solutions, a fuel performance simulation code must have the ability to obtain solutions for each of the physics, including coupling between them. Solution strategies for solving systems of coupled equations can be categorized as loosely-coupled, where the individual physics are solved separately, keeping the solutions for the other physics fixed at each iteration, or tightly coupled, where the nonlinear solver simultaneously drives down the residual for each physics, taking into account the coupling between the physics in each nonlinear iteration. In this paper, we compare the performance of loosely and tightly coupled solution algorithms for thermomechanical problems involving coupled thermal and mechanical contact, which is a primary source of interdependence between thermal and mechanical solutions in fuel performance models. The results indicate that loosely-coupled simulations require significantly more nonlinear iterations, and may lead to convergence trouble when the thermal conductivity of the gap is too small. We also apply the tightly coupled solution strategy to a nuclear fuel simulation of an experiment in a test reactor. Studying the results from these simulations indicates that perhaps convergence for either approach may be problem dependent, i.e., there may be problems for which a loose coupled approach converges, where tightly coupled won't converge and vice versa. (authors)

  17. Results from Tight and Loose Coupled Multiphysics in Nuclear Fuels Performance Simulations using BISON

    SciTech Connect

    S. R. Novascone; B. W. Spencer; D. Andrs; R. L. Williamson; J. D. Hales; D. M. Perez

    2013-05-01

    The behavior of nuclear fuel in the reactor environment is affected by multiple physics, most notably heat conduction and solid mechanics, which can have a strong influence on each other. To provide credible solutions, a fuel performance simulation code must have the ability to obtain solutions for each of the physics, including coupling between them. Solution strategies for solving systems of coupled equations can be categorized as loosely-coupled, where the individual physics are solved separately, keeping the solutions for the other physics fixed at each iteration, or tightly coupled, where the nonlinear solver simultaneously drives down the residual for each physics, taking into account the coupling between the physics in each nonlinear iteration. In this paper, we compare the performance of loosely and tightly coupled solution algorithms for thermomechanical problems involving coupled thermal and mechanical contact, which is a primary source of interdependence between thermal and mechanical solutions in fuel performance models. The results indicate that loosely-coupled simulations require significantly more nonlinear iterations, and may lead to convergence trouble when the thermal conductivity of the gap is too small. We also apply the tightly coupled solution strategy to a nuclear fuel simulation of an experiment in a test reactor. Studying the results from these simulations indicates that perhaps convergence for either approach may be problem dependent, i.e., there may be problems for which a loose coupled approach converges, where tightly coupled won’t converge and vice versa.

  18. Parallel adaptive fluid-structure interaction simulation of explosions impacting on building structures

    SciTech Connect

    Deiterding, Ralf; Wood, Stephen L

    2013-01-01

    We pursue a level set approach to couple an Eulerian shock-capturing fluid solver with space-time refinement to an explicit solid dynamics solver for large deformations and fracture. The coupling algorithms considering recursively finer fluid time steps as well as overlapping solver updates are discussed in detail. Our ideas are implemented in the AMROC adaptive fluid solver framework and are used for effective fluid-structure coupling to the general purpose solid dynamics code DYNA3D. Beside simulations verifying the coupled fluid-structure solver and assessing its parallel scalability, the detailed structural analysis of a reinforced concrete column under blast loading and the simulation of a prototypical blast explosion in a realistic multistory building are presented.

  19. Track structure based modelling of light ion radiation effects on nuclear and mitochondrial DNA

    NASA Astrophysics Data System (ADS)

    Schmitt, Elke; Ottolenghi, Andrea; Dingfelder, Michael; Friedland, Werner; Kundrat, Pavel; Baiocco, Giorgio

    2016-07-01

    Space radiation risk assessment is of great importance for manned spaceflights in order to estimate risks and to develop counter-measures to reduce them. Biophysical simulations with PARTRAC can help greatly to improve the understanding of initial biological response to ionizing radiation. Results from modelling radiation quality dependent DNA damage and repair mechanisms up to chromosomal aberrations (e.g. dicentrics) can be used to predict radiation effects depending on the kind of mixed radiation field exposure. Especially dicentric yields can serve as a biomarker for an increased risk due to radiation and hence as an indicator for the effectiveness of the used shielding. PARTRAC [1] is a multi-scale biophysical research MC code for track structure based initial DNA damage and damage response modelling. It integrates physics, radiochemistry, detailed nuclear DNA structure and molecular biology of DNA repair by NHEJ-pathway to assess radiation effects on cellular level [2]. Ongoing experiments with quasi-homogeneously distributed compared to sub-micrometre focused bunches of protons, lithium and carbon ions allow a separation of effects due to DNA damage complexity on nanometre scale from damage clustering on (sub-) micrometre scale [3, 4]. These data provide an unprecedented benchmark for the DNA damage response model in PARTRAC and help understand the mechanisms leading to cell killing and chromosomal aberrations (e.g. dicentrics) induction. A large part of space radiation is due to a mixed ion field of high energy protons and few heavier ions that can be only partly absorbed by the shielding. Radiation damage induced by low-energy ions significantly contributes to the high relative biological efficiency (RBE) of ion beams around Bragg peak regions. For slow light ions the physical cross section data basis in PARTRAC has been extended to investigate radiation quality effects in the Bragg peak region [5]. The resulting range and LET values agree with ICRU data

  20. Exploring protein flexibility: incorporating structural ensembles from crystal structures and simulation into virtual screening protocols.

    PubMed

    Osguthorpe, David J; Sherman, Woody; Hagler, Arnold T

    2012-06-14

    The capacity of proteins to adapt their structure in response to various perturbations including covalent modifications, and interactions with ligands and other proteins plays a key role in biological processes. Here, we explore the ability of molecular dynamics (MD), replica exchange molecular dynamics (REMD), and a library of structures of crystal-ligand complexes, to sample the protein conformational landscape and especially the accessible ligand binding site geometry. The extent of conformational space sampled is measured by the diversity of the shapes of the ligand binding sites. Since our focus here is the effect of this plasticity on the ability to identify active compounds through virtual screening, we use the structures generated by these techniques to generate a small ensemble for further docking studies, using binding site shape hierarchical clustering to determine four structures for each ensemble. These are then assessed for their capacity to optimize enrichment and diversity in docking. We test these protocols on three different receptors: androgen receptor (AR), HIV protease, and CDK2. We show that REMD enhances structural sampling slightly as compared both to MD, and the distortions induced by ligand binding as reflected in the crystal structures. The improved sampling of the simulation methods does not translate directly into improved docking performance, however. The ensemble approach did improve enrichment and diversity, and the ensemble derived from the crystal structures performed somewhat better than those derived from the simulations. PMID:22424156

  1. Neutral Buoyancy Simulator-NB32-Large Space Structure Assembly

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Once the United States' space program had progressed from Earth's orbit into outerspace, the prospect of building and maintaining a permanent presence in space was realized. To accomplish this feat, NASA launched a temporary workstation, Skylab, to discover the effects of low gravity and weightlessness on the human body, and also to develop tools and equipment that would be needed in the future to build and maintain a more permanent space station. The structures, techniques, and work schedules had to be carefully designed to fit this unique construction site. The components had to be lightweight for transport into orbit, yet durable. The station also had to be made with removable parts for easy servicing and repairs by astronauts. All of the tools necessary for service and repairs had to be designed for easy manipulation by a suited astronaut. Construction methods had to be efficient due to the limited time the astronauts could remain outside their controlled environment. In lieu of all the specific needs for this project, an environment on Earth had to be developed that could simulate a low gravity atmosphere. A Neutral Buoyancy Simulator (NBS) was constructed by NASA Marshall Space Flight Center (MSFC) in 1968. Since then, NASA scientists have used this facility to understand how humans work best in low gravity and also provide information about the different kinds of structures that can be built. As part of this experimentation, the Experimental Assembly of Structures in Extravehicular Activity (EASE) project was developed as a joint effort between MFSC and the Massachusetts Institute of Technology (MIT). The EASE experiment required that crew members assemble small components to form larger components, working from the payload bay of the space shuttle. Pictured is an entire unit that has been constructed and is sitting in the bottom of a mock-up shuttle cargo bay pallet.

  2. Nur77 forms novel nuclear structures upon DNA damage that cause transcriptional arrest

    SciTech Connect

    Leseleuc, Louis de; Denis, Francois . E-mail: francois.denis@iaf.inrs.ca

    2006-05-15

    The orphan nuclear receptor Nur77 has been implicated in both growth and apoptosis, and its function and activity can be modulated by cellular redistribution. Green fluorescent protein-tagged Nur77 was used to evaluate the role of Nur77 intracellular redistribution in response to genotoxic stress. Selected DNA damaging agents and transcription inhibition lead to rapid redistribution of Nur77 into nuclear structures distinct from conventional nuclear bodies. These nuclear bodies formed transiently were tightly bound to the nuclear matrix and conditions that lead to their appearance were associated with Nur77 transcriptional inhibition. The formation of Nur77 nuclear bodies might be involved in programmed cell death modulation upon exposure to DNA damaging agents that inhibit transcription by sequestrating this proapoptotic factor in dense nuclear structures.

  3. Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments.

    PubMed

    Szőke, I; Louka, M N; Bryntesen, T R; Bratteli, J; Edvardsen, S T; RøEitrheim, K K; Bodor, K

    2014-06-01

    This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation's lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers.IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry.This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors. PMID:24727389

  4. Analysis of statistical model properties from discrete nuclear structure data

    NASA Astrophysics Data System (ADS)

    Firestone, Richard B.

    2012-02-01

    Experimental M1, E1, and E2 photon strengths have been compiled from experimental data in the Evaluated Nuclear Structure Data File (ENSDF) and the Evaluated Gamma-ray Activation File (EGAF). Over 20,000 Weisskopf reduced transition probabilities were recovered from the ENSDF and EGAF databases. These transition strengths have been analyzed for their dependence on transition energies, initial and final level energies, spin/parity dependence, and nuclear deformation. ENSDF BE1W values were found to increase exponentially with energy, possibly consistent with the Axel-Brink hypothesis, although considerable excess strength observed for transitions between 4-8 MeV. No similar energy dependence was observed in EGAF or ARC data. BM1W average values were nearly constant at all energies above 1 MeV with substantial excess strength below 1 MeV and between 4-8 MeV. BE2W values decreased exponentially by a factor of 1000 from 0 to 16 MeV. The distribution of ENSDF transition probabilities for all multipolarities could be described by a lognormal statistical distribution. BE1W, BM1W, and BE2W strengths all increased substantially for initial transition level energies between 4-8 MeV possibly due to dominance of spin-flip and Pygmy resonance transitions at those excitations. Analysis of the average resonance capture data indicated no transition probability dependence on final level spins or energies between 0-3 MeV. The comparison of favored to unfavored transition probabilities for odd-A or odd-Z targets indicated only partial support for the expected branching intensity ratios with many unfavored transitions having nearly the same strength as favored ones. Average resonance capture BE2W transition strengths generally increased with greater deformation. Analysis of ARC data suggest that there is a large E2 admixture in M1 transitions with the mixing ratio δ ≈ 1.0. The ENSDF reduced transition strengths were considerably stronger than those derived from capture gamma ray

  5. ALMOST: an all atom molecular simulation toolkit for protein structure determination.

    PubMed

    Fu, Biao; Sahakyan, Aleksandr B; Camilloni, Carlo; Tartaglia, Gian Gaetano; Paci, Emanuele; Caflisch, Amedeo; Vendruscolo, Michele; Cavalli, Andrea

    2014-05-30

    Almost (all atom molecular simulation toolkit) is an open source computational package for structure determination and analysis of complex molecular systems including proteins, and nucleic acids. Almost has been designed with two primary goals: to provide tools for molecular structure determination using various types of experimental measurements as conformational restraints, and to provide methods for the analysis and assessment of structural and dynamical properties of complex molecular systems. The methods incorporated in Almost include the determination of structural and dynamical features of proteins using distance restraints derived from nuclear Overhauser effect measurements, orientational restraints obtained from residual dipolar couplings and the structural restraints from chemical shifts. Here, we present the first public release of Almost, highlight the key aspects of its computational design and discuss the main features currently implemented. Almost is available for the most common Unix-based operating systems, including Linux and Mac OS X. Almost is distributed free of charge under the GNU Public License, and is available both as a source code and as a binary executable from the project web site at http://www.open-almost.org. Interested users can follow and contribute to the further development of Almost on http://sourceforge.net/projects/almost. PMID:24676684

  6. Structures and regulation of non-X orphan nuclear receptors: A retinoid hypothesis.

    PubMed

    Zhi, Xiaoyong; Zhou, X Edward; Melcher, Karsten; Xu, H Eric

    2016-03-01

    Nuclear receptors are defined as a family of ligand regulated transcription factors [1-6]. While this definition reflects that ligand binding is a key property of nuclear receptors, it is still a heated subject of debate if all the nuclear receptors (48 human members) can bind ligands (ligands referred here to both physiological and synthetic ligands). Recent studies in nuclear receptor structure biology and pharmacology have undoubtedly increased our knowledge of nuclear receptor functions and their regulation. As a result, they point to new avenues for the discovery and development of nuclear receptor regulators, including nuclear receptor ligands. Here we review the recent literature on orphan nuclear receptor structural analysis and ligand identification, particularly on the orphan nuclear receptors that do not heterodimerize with retinoid X receptors, which we term as non-X orphan receptors. We also propose a speculative "retinoid hypothesis" for a subset of non-X orphan nuclear receptors, which we hope to help shed light on orphan nuclear receptor biology and drug discovery. This article is part of a Special Issue entitled 'Orphan Nuclear Receptors'. PMID:26159912

  7. Numerical simulation of the thermal conditions in a sea bay water area used for water supply to nuclear power plants

    SciTech Connect

    Sokolov, A. S.

    2013-07-15

    Consideration is given to the numerical simulation of the thermal conditions in sea water areas used for both water supply to and dissipation of low-grade heat from a nuclear power plant on the shore of a sea bay.

  8. Tyrosine Aminotransferase: Biochemical and Structural Properties and Molecular Dynamics Simulations

    SciTech Connect

    P Mehere; Q Han; J Lemkul; C Vavricka; H Robinson; D Bevan; J Li

    2011-12-31

    Tyrosine aminotransferase (TAT) catalyzes the transamination of tyrosine and other aromatic amino acids. The enzyme is thought to play a role in tyrosinemia type II, hepatitis and hepatic carcinoma recovery. The objective of this study is to investigate its biochemical and structural characteristics and substrate specificity in order to provide insight regarding its involvement in these diseases. Mouse TAT (mTAT) was cloned from a mouse cDNA library, and its recombinant protein was produced using Escherichia coli cells and purified using various chromatographic techniques. The recombinant mTAT is able to catalyze the transamination of tyrosine using {alpha}-ketoglutaric acid as an amino group acceptor at neutral pH. The enzyme also can use glutamate and phenylalanine as amino group donors and p-hydroxy-phenylpyruvate, phenylpyruvate and alpha-ketocaproic acid as amino group acceptors. Through macromolecular crystallography we have determined the mTAT crystal structure at 2.9 {angstrom} resolution. The crystal structure revealed the interaction between the pyridoxal-5'-phosphate cofactor and the enzyme, as well as the formation of a disulphide bond. The detection of disulphide bond provides some rational explanation regarding previously observed TAT inactivation under oxidative conditions and reactivation of the inactive TAT in the presence of a reducing agent. Molecular dynamics simulations using the crystal structures of Trypanosoma cruzi TAT and human TAT provided further insight regarding the substrate-enzyme interactions and substrate specificity. The biochemical and structural properties of TAT and the binding of its cofactor and the substrate may help in elucidation of the mechanism of TAT inhibition and activation.

  9. Tyrosine aminotransferase: biochemical and structural properties and molecular dynamics simulations

    SciTech Connect

    Mehere, P.; Robinson, H.; Han, Q.; Lemkul, J. A.; Vavricka, C. J.; Bevan, D. R.; Li, J.

    2010-11-01

    Tyrosine aminotransferase (TAT) catalyzes the transamination of tyrosine and other aromatic amino acids. The enzyme is thought to play a role in tyrosinemia type II, hepatitis and hepatic carcinoma recovery. The objective of this study is to investigate its biochemical and structural characteristics and substrate specificity in order to provide insight regarding its involvement in these diseases. Mouse TAT (mTAT) was cloned from a mouse cDNA library, and its recombinant protein was produced using Escherichia coli cells and purified using various chromatographic techniques. The recombinant mTAT is able to catalyze the transamination of tyrosine using {alpha}-ketoglutaric acid as an amino group acceptor at neutral pH. The enzyme also can use glutamate and phenylalanine as amino group donors and p-hydroxy-phenylpyruvate, phenylpyruvate and alpha-ketocaproic acid as amino group acceptors. Through macromolecular crystallography we have determined the mTAT crystal structure at 2.9 {angstrom} resolution. The crystal structure revealed the interaction between the pyridoxal-5'-phosphate cofactor and the enzyme, as well as the formation of a disulphide bond. The detection of disulphide bond provides some rational explanation regarding previously observed TAT inactivation under oxidative conditions and reactivation of the inactive TAT in the presence of a reducing agent. Molecular dynamics simulations using the crystal structures of Trypanosoma cruzi TAT and human TAT provided further insight regarding the substrate-enzyme interactions and substrate specificity. The biochemical and structural properties of TAT and the binding of its cofactor and the substrate may help in elucidation of the mechanism of TAT inhibition and activation.

  10. Aging management of safety-related concrete structures in nuclear power plants

    SciTech Connect

    Naus, D.J.; Oland, C.B. ); Arndt, E.G. )

    1990-01-01

    The Structural Aging Program has the overall objective of providing the US Nuclear Regulatory Commission with an improved basis for evaluating nuclear power plants for continued service. In meeting this objective, a materials property data base is being developed as well as an aging assessment methodology for concrete structures in nuclear power plants. Furthermore, studies are well under way to review and assess inservice inspection techniques for concrete structures and to develop a methodology which can be used for performing current as well as reliability-based future conditions assessments of these structures. 16 refs., 2 tabs.

  11. Filamented ion tail structures at Titan: A hybrid simulation study

    NASA Astrophysics Data System (ADS)

    Feyerabend, Moritz; Simon, Sven; Motschmann, Uwe; Liuzzo, Lucas

    2015-11-01

    This study investigates the processes that lead to the detection of split signatures in ion density during several crossings of the Cassini spacecraft through Titan's mid-range plasma tail (T9, T63, and T75). During each of these flybys, the Cassini Plasma Spectrometer detected Titan's ionospheric ion population twice; i.e., the spacecraft passed through two spatially separated regions where cold ions were detected, with the regions also being dominated by ions of different masses in the case of T9. Whether this filamented tail structure is an omnipresent feature of Titan's plasma interaction or a result of non-stationary upstream conditions during specific flybys is still unclear. To explain these features, we apply the hybrid simulation code AIKEF (kinetic ions and fluid electrons). Our model includes chemical reactions as well as a realistic photoionization model for a sophisticated description of the ionospheric composition of Titan. Our simulations show that the filamentation of Titan's tail is indeed a common feature of the moon's plasma interaction. Light ionospheric species escape along draped magnetic field lines to form a parabolically shaped filament structure, which is mainly seen in planes that contain the upstream magnetospheric magnetic field and the upstream flow direction. In addition, transport of ions of all species from the ramside towards downstream produces a cone structure behind Titan, with a region of decreased density inside and filaments of 1-2 RT (RT=2575 km) thickness and enhanced density at the surface of the cone. Spacecraft trajectories that penetrate these structures allow for the detection of split signatures in the tail. The orientation of the upstream magnetic field and plasma flow as well as local time effects (i.e., Titan's orbital position) influence the location of the filaments in the tail and can also cause asymmetries in their sizes and densities. The detection of the split signatures along a spacecraft trajectory may

  12. Computer simulation of the structure of ionic surfaces and interfaces

    SciTech Connect

    Wolf, D.

    1994-09-01

    The classic Madelung problem, i.e., the divergence associated with the r{sup {minus}1} term in the Coulomb potential of condensed ionic systems, was recently cast into an absolutely convergent form that is readily evaluated by direct lattice summation, revealing a net r{sup {minus}5} range of this potential. This realization that Coulomb interactions in condensed systems can actually be rather short ranged (if the system is overall neutral) permits novel physical insights into their structure and energetics to be gained. As an example, the authors demonstrate that an understanding of the range and the nature of the convergence of the Coulomb potential leads naturally to the prediction, verified here by computer simulations for rocksalt-structured surfaces, that all surfaces in predominantly ionic materials should be fundamentally reconstructed. The work also provides a conceptual framework for the theoretical treatment of polar surfaces and interfaces, as demonstrated here for the case of the (111) stacking fault and of the (111) twin boundary in the rocksalt structure.

  13. A Perspective on Coupled Multiscale Simulation and Validation in Nuclear Materials

    SciTech Connect

    M. P. Short; D. Gaston; C. R. Stanek; S. Yip

    2014-01-01

    The field of nuclear materials encompasses numerous opportunities to address and ultimately solve longstanding industrial problems by improving the fundamental understanding of materials through the integration of experiments with multiscale modeling and high-performance simulation. A particularly noteworthy example is an ongoing study of axial power distortions in a nuclear reactor induced by corrosion deposits, known as CRUD (Chalk River unidentified deposits). We describe how progress is being made toward achieving scientific advances and technological solutions on two fronts. Specifically, the study of thermal conductivity of CRUD phases has augmented missing data as well as revealed new mechanisms. Additionally, the development of a multiscale simulation framework shows potential for the validation of a new capability to predict the power distribution of a reactor, in effect direct evidence of technological impact. The material- and system-level challenges identified in the study of CRUD are similar to other well-known vexing problems in nuclear materials, such as irradiation accelerated corrosion, stress corrosion cracking, and void swelling; they all involve connecting materials science fundamentals at the atomistic- and mesoscales to technology challenges at the macroscale.

  14. Frontiers of Nuclear Structure Physics - Proceedings of the International Symposium held in Honor of Akito Arima

    NASA Astrophysics Data System (ADS)

    Ishihara, M.; Otsuka, T.; Mizusaki, T.; Yazaki, K.

    1996-01-01

    The Table of Contents for the full book PDF is as follows: * Preface * Aspects of the structure of light nuclei * A frontier of shell model calculation: large-scale calculation with G-matrix interaction in middle pf-shell * Realistic large-basis shell-model calculation in the low-mass tin isotopes * Isospin symmetry breaking in light nuclei * The role of pairing in nuclear collective motion * Universal correlations of collective observables: empirical phenomenology and model interpretations * Interacting Boson Model for O(6) nuclei * Multiple Q-phonon modes in even barium nuclei * Two-phonon γ-vibrational states in deformed nuclei * Scattering of GeV electrons by nuclei * Nuclear structure experiments at CEBAF * Correlations and relativistic features in nuclear structure * Collective string-like model of baryons * Hadron-nucleon scattering lengths in QCD sum rules * Atomic yrast brands of metastable amiprotonic helium atomcules * Loosely coupling few-body systems * Nuclear spin responses in astroparticle physics * Towards extremes of nuclear states with radioactive beams * Strangeness Nuclear Physics: experimental tests of quark-based pictures * Deep hole states and hypernuclei * Simple two-body effective-interaction matrix elements and realistic microscopic nuclear-structure calculations * Signature and parity splitting in rotational bands: double minimal potential model * Search for mixed-symmetry states in O(6) nuclei * From the shell model to the interacting boson model * Optimal pair description of nuclear motions in a degenerate orbit * Some current topics in nuclear structure at drip lines * Halo structure of light neutron-rich nuclei * Nucleosynthesis in explosive hydrogen burning process * Nuclear astrophysics with secondary (radioactive) beams * Magnetic moments: A microscopic look into the nuclear structure of medium weight and heavy nuclei * Laser trapping of radioactive atoms * Chiral perturbation in dense matter and meson condensation controversy

  15. Uncertainty analysis of atmospheric deposition simulation of radiocesium and radioiodine from Fukushima Daiichi Nuclear Power Plant

    NASA Astrophysics Data System (ADS)

    Morino, Yu; Ohara, Toshimasa; Yumimoto, Keiya

    2014-05-01

    Chemical transport models (CTM) played key roles in understanding the atmospheric behaviors and deposition patterns of radioactive materials emitted from the Fukushima Daiichi nuclear power plant (FDNPP) after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011. In this study, we assessed uncertainties of atmospheric simulation by comparing observed and simulated deposition of radiocesium (137Cs) and radioiodine (131I). Airborne monitoring survey data were used to assess the model performance of 137Cs deposition patterns. We found that simulation using emissions estimated with a regional-scale (~500 km) CTM better reproduced the observed 137Cs deposition pattern in eastern Japan than simulation using emissions estimated with local-scale (~50 km) or global-scale CTM. In addition, we estimated the emission amount of 137Cs from FDNPP by combining a CTM, a priori source term, and observed deposition data. This is the first use of airborne survey data of 137Cs deposition (more than 16,000 data points) as the observational constraints in inverse modeling. The model simulation driven by a posteriori source term achieved better agreements with 137Cs depositions measured by aircraft survey and at in-situ stations over eastern Japan. Wet deposition module was also evaluated. Simulation using a process-based wet deposition module reproduced the observations well, whereas simulation using scavenging coefficients showed large uncertainties associated with empirical parameters. The best-available simulation reproduced the observed 137Cs deposition rates in high-deposition areas (≥10 kBq m-2) within one order of magnitude. Recently, 131I deposition map was released and helped to evaluate model performance of 131I deposition patterns. Observed 131I/137Cs deposition ratio is higher in areas southwest of FDNPP than northwest of FDNPP, and this behavior was roughly reproduced by a CTM if we assume that released 131I is more in gas phase

  16. Probabilistic simulation of the human factor in structural reliability

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1993-01-01

    A formal approach is described in an attempt to computationally simulate the probable ranges of uncertainties of the human factor in structural probabilistic assessments. A multi-factor interaction equation (MFIE) model has been adopted for this purpose. Human factors such as marital status, professional status, home life, job satisfaction, work load and health, are considered to demonstrate the concept. Parametric studies in conjunction with judgment are used to select reasonable values for the participating factors (primitive variables). Suitability of the MFIE in the subsequently probabilistic sensitivity studies are performed to assess the validity of the whole approach. Results obtained show that the uncertainties for no error range from five to thirty percent for the most optimistic case.

  17. Development and mechanical properties of structural materials from lunar simulant

    NASA Technical Reports Server (NTRS)

    Desai, Chandra S.

    1991-01-01

    Development of versatile engineering materials from locally available materials in space is an important step toward establishment of outposts such as on the moon and Mars. Here 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. It is also vital that the mechanical behavior such as strength and flexural properties, fracture toughness, ductility, and deformation characteristics are defined toward establishment of the ranges of engineering applications of the materials developed. The objectives include two areas: (1) thermal liquefaction of lunar simulant (at about 1100 C) with different additives (fibers, powders, etc.); and (2) development and use of a traxial test device in which lunar simulants are first compacted under cycles of loading, and then tested with different vacuums and initial confining or insitu stress. The second area was described in previous progress reports and publications; since the presently available device allows vacuum levels up to only 10(exp -4) torr, it is recommended that a vacuum pump that can allow higher levels of vacuum is acquired.

  18. Immersed boundary methods for simulating fluid-structure interaction

    NASA Astrophysics Data System (ADS)

    Sotiropoulos, Fotis; Yang, Xiaolei

    2014-02-01

    Fluid-structure interaction (FSI) problems commonly encountered in engineering and biological applications involve geometrically complex flexible or rigid bodies undergoing large deformations. Immersed boundary (IB) methods have emerged as a powerful simulation tool for tackling such flows due to their inherent ability to handle arbitrarily complex bodies without the need for expensive and cumbersome dynamic re-meshing strategies. Depending on the approach such methods adopt to satisfy boundary conditions on solid surfaces they can be broadly classified as diffused and sharp interface methods. In this review, we present an overview of the fundamentals of both classes of methods with emphasis on solution algorithms for simulating FSI problems. We summarize and juxtapose different IB approaches for imposing boundary conditions, efficient iterative algorithms for solving the incompressible Navier-Stokes equations in the presence of dynamic immersed boundaries, and strong and loose coupling FSI strategies. We also present recent results from the application of such methods to study a wide range of problems, including vortex-induced vibrations, aquatic swimming, insect flying, human walking and renewable energy. Limitations of such methods and the need for future research to mitigate them are also discussed.

  19. A simulation model for analysing brain structure deformations

    NASA Astrophysics Data System (ADS)

    Di Bona, Sergio; Lutzemberger, Ludovico; Salvetti, Ovidio

    2003-12-01

    Recent developments of medical software applications—from the simulation to the planning of surgical operations—have revealed the need for modelling human tissues and organs, not only from a geometric point of view but also from a physical one, i.e. soft tissues, rigid body, viscoelasticity, etc. This has given rise to the term 'deformable objects', which refers to objects with a morphology, a physical and a mechanical behaviour of their own and that reflects their natural properties. In this paper, we propose a model, based upon physical laws, suitable for the realistic manipulation of geometric reconstructions of volumetric data taken from MR and CT scans. In particular, a physically based model of the brain is presented that is able to simulate the evolution of different nature pathological intra-cranial phenomena such as haemorrhages, neoplasm, haematoma, etc and to describe the consequences that are caused by their volume expansions and the influences they have on the anatomical and neuro-functional structures of the brain.

  20. Linking Microbial Community Structure to Function in Representative Simulated Systems

    PubMed Central

    Marcus, Ian M.; Wilder, Hailey A.; Quazi, Shanin J.

    2013-01-01

    Pathogenic bacteria are generally studied as a single strain under ideal growing conditions, although these conditions are not the norm in the environments in which pathogens typically proliferate. In this investigation, a representative microbial community along with Escherichia coli O157:H7, a model pathogen, was studied in three environments in which such a pathogen could be found: a human colon, a septic tank, and groundwater. Each of these systems was built in the lab in order to retain the physical/chemical and microbial complexity of the environments while maintaining control of the feed into the models. The microbial community in the colon was found to have a high percentage of bacteriodetes and firmicutes, while the septic tank and groundwater systems were composed mostly of proteobacteria. The introduction of E. coli O157:H7 into the simulated systems elicited a shift in the structures and phenotypic cell characteristics of the microbial communities. The fate and transport of the microbial community with E. coli O157:H7 were found to be significantly different from those of E. coli O157:H7 studied as a single isolate, suggesting that the behavior of the organism in the environment was different from that previously conceived. The findings in this study clearly suggest that to gain insight into the fate of pathogens, cells should be grown and analyzed under conditions simulating those of the environment in which the pathogens are present. PMID:23396331