WorldWideScience

Sample records for cone simulation project

  1. A GPU Tool for Efficient, Accurate, and Realistic Simulation of Cone Beam CT Projections

    CERN Document Server

    Jia, Xun; Cervino, Laura; Folkerts, Michael; Jiang, Steve B

    2012-01-01

    Simulation of x-ray projection images plays an important role in cone beam CT (CBCT) related research projects. A projection image contains primary signal, scatter signal, and noise. It is computationally demanding to perform accurate and realistic computations for all of these components. In this work, we develop a package on GPU, called gDRR, for the accurate and efficient computations of x-ray projection images in CBCT under clinically realistic conditions. The primary signal is computed by a tri-linear ray-tracing algorithm. A Monte Carlo (MC) simulation is then performed, yielding the primary signal and the scatter signal, both with noise. A denoising process is applied to obtain a smooth scatter signal. The noise component is then obtained by combining the difference between the MC primary and the ray-tracing primary signals, and the difference between the MC simulated scatter and the denoised scatter signals. Finally, a calibration step converts the calculated noise signal into a realistic one by scali...

  2. Gradient angle estimation by uniform directional simulation on a cone

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    1997-01-01

    of these projections is derived assuming the limit-state surface to be a hyperplane. This distribution depends on the angle between the cone axis and the normal vector to the hyperplane. Assuming sufficient flatness of the actual limit-state surface within a neighbourhood of the cut point with the cone axis, the cone...... top angle can be chosen small enough that this distribution can be taken as the basis for the formulation of the likelihood function of the angle given the sample of projections. The angle of maximum likelihood is then the indicator of whether the cut point can be taken as a sufficiently accurate...... approximation to a locally most central limit state point. Moreover, the estimated angle can be used to correct the geometric reliability index.\\bfseries Keywords: Directional simulation, effectivity factor, gradient angle estimation, maximum likelihood, model-correction-factor method, Monte Carlo simulation...

  3. A simplified approach for the generation of projection data for cone ...

    Indian Academy of Sciences (India)

    Following the same line of argument as above, the effective ray path in the voxel ... For cone beam data collection geometry, arguing on similar lines, the projection data. gϕ,η at cone angle ϕ and fan .... For numerical simulation purpose, Phantom 1 was discretized on a regular grid of 101 ×. 101 × 241 units. The projections ...

  4. Vacuum Compatible Percussive Dynamic Cone Penetrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics proposes to develop a vacuum compatible percussive dynamic cone penetrometer (PDCP), for establishing soil bin characteristics, with the ultimate...

  5. Increasing Cone-beam projection usage by temporal fitting

    DEFF Research Database (Denmark)

    Lyksborg, Mark; Hansen, Mads Fogtmann; Larsen, Rasmus

    2010-01-01

    A Cone-beam CT system can be used to image the lung region. The system records 2D projections which will allow 3D reconstruction however a reconstruction based on all projections will lead to a blurred reconstruction in regions were respiratory motion occur. To avoid this the projections are typi...... on Poisons assumptions using an L-BFGS-B optimizer [5]. It will be demonstrated on a phantom data set that the information gained from a 4D model leads to smaller reconstruction errors than a 3D iterative reconstruction based on phase binned data.......A Cone-beam CT system can be used to image the lung region. The system records 2D projections which will allow 3D reconstruction however a reconstruction based on all projections will lead to a blurred reconstruction in regions were respiratory motion occur. To avoid this the projections...... in [6] prior knowledge of the lung deformation estimated from the planning CT could be used to include all projections into the reconstruction. It has also been attempted to estimate both the motion and 3D volume simultaneously in [4]. Problems with motion estimation are ill-posed leading to suboptimal...

  6. Extracting respiratory signals from thoracic cone beam CT projections

    CERN Document Server

    Yan, Hao; Yin, Wotao; Pan, Tinsu; Ahmad, Moiz; Mou, Xuanqin; Cervino, Laura; Jia, Xun; Jiang, Steve B

    2012-01-01

    Patient respiratory signal associated with the cone beam CT (CBCT) projections is important for lung cancer radiotherapy. In contrast to monitoring an external surrogate of respiration, such signal can be extracted directly from the CBCT projections. In this paper, we propose a novel local principle component analysis (LPCA) method to extract the respiratory signal by distinguishing the respiration motion-induced content change from the gantry rotation-induced content change in the CBCT projections. The LPCA method is evaluated by comparing with three state-of-the-art projection-based methods, namely, the Amsterdam Shroud (AS) method, the intensity analysis (IA) method, and the Fourier-transform based phase analysis (FT-p) method. The clinical CBCT projection data of eight patients, acquired under various clinical scenarios, were used to investigate the performance of each method. We found that the proposed LPCA method has demonstrated the best overall performance for cases tested and thus is a promising tech...

  7. Geometric VOF-PLIC simulations of Hollow Cone Sprays

    Science.gov (United States)

    Nelson, Thomas; Benson, Michael; Vanpoppel, Brett; Bravo, Luis; USMA Team Spray Collaboration; ARL Vehicle Combustion Lab Collaboration; Stanford University Collaboration

    2014-11-01

    This work examines a Computational Fluid Dynamics (CFD) approach to provide temporally resolved simulations of a novel pressure swirl atomizer presently studied at Stanford University. In a pressure swirl atomizer, the liquid spreads out to form an air-cored vortex within the nozzle and an emerging thin annular film. Due to instabilities the film breaks up to form a hollow cone spray. The numerical simulations focus on the near field nozzle flow physics and primary atomization of the spray. An incompressible flow formulation is adopted with a geometric unsplit Volume of Fluid (VOF) method to track the interface between two immiscible fluids in interfacial flow simulations. Here, the interface is modeled via an advection equation implicitly tracked using a discrete indicator function, f, with values representing the volume fraction of the tagged fluid within a cell. An Adaptive Mesh Refinement (AMR) scheme is also employed to efficiently capture the shear layers near the liquid-gas interface. The study is carried out for two atomizers with 2 mm and 3 mm diameters at intermediate Re = 2.6-3.9 × 103, We = 0.11-0.17 × 105. An in depth comparison is then provided between the CFD results and measurements obtained via shadowgraphy and CT scans.

  8. Simulation of Heat Transfer in Husk Furnace with Cone Geometry Based on Conical Coordinate System

    Science.gov (United States)

    Noor, Iman; Ahmad, Faozan; Irzaman; alatas, Husin

    2017-07-01

    Simulation of Heat Transfer in Husk Furnace with Cone Geometry Based on Conical Coordinates has been performed. This simulation aimed to study the heat distribution of temperature based on conduction and convection mechanism on conical coordinate system. Fluid dynamics inside the cone of husk furnace was obtained by solving the Navier - Stokes equations with laminar flow approach. The initial temperature in all parts of the cone is room temperature, except at the bottom of the cone is 700 °C. Through numerical calculation of heat conduction and convection equation by FDM method, we got that the velocity of fluid flow at the center cone is 13.69 m/s for 45 s, 11.90 m/s for 60 s, and 7.25 m/s for 120 s, with unfixed temperature condition in the cone.

  9. liger: mock relativistic light cones from Newtonian simulations

    Science.gov (United States)

    Borzyszkowski, Mikolaj; Bertacca, Daniele; Porciani, Cristiano

    2017-11-01

    We introduce a method to create mock galaxy catalogues in redshift space including general relativistic effects to linear order in the cosmological perturbations. We dub our method liger, short for `light cones with general relativity'. liger takes a (N-body or hydrodynamic) Newtonian simulation as an input and outputs the distribution of galaxies in comoving redshift space. This result is achieved making use of a coordinate transformation and simultaneously accounting for lensing magnification. The calculation includes both local corrections and terms that have been integrated along the line of sight. Our fast implementation allows the production of many realizations that can be used to forecast the performance of forthcoming wide-angle surveys and to estimate the covariance matrix of the observables. To facilitate this use, we also present a variant of liger designed for large-volume simulations with low-mass resolution. In this case, the galaxy distribution on large scales is obtained by biasing the matter-density field. Finally, we present two sample applications of liger. First, we discuss the impact of weak gravitational lensing on to the angular clustering of galaxies in a Euclid-like survey. In agreement with previous analytical studies, we find that magnification bias can be measured with high confidence. Secondly, we focus on two generally neglected Doppler-induced effects: magnification and the change of number counts with redshift. We show that the corresponding redshift-space distortions can be detected at 5.5σ significance with the completed Square Kilometre Array.

  10. Ultrafast cone-beam CT scatter correction with GPU-based Monte Carlo simulation

    Directory of Open Access Journals (Sweden)

    Yuan Xu

    2014-03-01

    Full Text Available Purpose: Scatter artifacts severely degrade image quality of cone-beam CT (CBCT. We present an ultrafast scatter correction framework by using GPU-based Monte Carlo (MC simulation and prior patient CT image, aiming at automatically finish the whole process including both scatter correction and reconstruction within 30 seconds.Methods: The method consists of six steps: 1 FDK reconstruction using raw projection data; 2 Rigid Registration of planning CT to the FDK results; 3 MC scatter calculation at sparse view angles using the planning CT; 4 Interpolation of the calculated scatter signals to other angles; 5 Removal of scatter from the raw projections; 6 FDK reconstruction using the scatter-corrected projections. In addition to using GPU to accelerate MC photon simulations, we also use a small number of photons and a down-sampled CT image in simulation to further reduce computation time. A novel denoising algorithm is used to eliminate MC noise from the simulated scatter images caused by low photon numbers. The method is validated on one simulated head-and-neck case with 364 projection angles.Results: We have examined variation of the scatter signal among projection angles using Fourier analysis. It is found that scatter images at 31 angles are sufficient to restore those at all angles with < 0.1% error. For the simulated patient case with a resolution of 512 × 512 × 100, we simulated 5 × 106 photons per angle. The total computation time is 20.52 seconds on a Nvidia GTX Titan GPU, and the time at each step is 2.53, 0.64, 14.78, 0.13, 0.19, and 2.25 seconds, respectively. The scatter-induced shading/cupping artifacts are substantially reduced, and the average HU error of a region-of-interest is reduced from 75.9 to 19.0 HU.Conclusion: A practical ultrafast MC-based CBCT scatter correction scheme is developed. It accomplished the whole procedure of scatter correction and reconstruction within 30 seconds.----------------------------Cite this

  11. Projection matrix acquisition for cone-beam computed tomography iterative reconstruction

    Science.gov (United States)

    Yang, Fuqiang; Zhang, Dinghua; Huang, Kuidong; Shi, Wenlong; Zhang, Caixin; Gao, Zongzhao

    2017-02-01

    Projection matrix is an essential and time-consuming part in computed tomography (CT) iterative reconstruction. In this article a novel calculation algorithm of three-dimensional (3D) projection matrix is proposed to quickly acquire the matrix for cone-beam CT (CBCT). The CT data needed to be reconstructed is considered as consisting of the three orthogonal sets of equally spaced and parallel planes, rather than the individual voxels. After getting the intersections the rays with the surfaces of the voxels, the coordinate points and vertex is compared to obtain the index value that the ray traversed. Without considering ray-slope to voxel, it just need comparing the position of two points. Finally, the computer simulation is used to verify the effectiveness of the algorithm.

  12. Project Schedule Simulation

    DEFF Research Database (Denmark)

    Mizouni, Rabeb; Lazarova-Molnar, Sanja

    2015-01-01

    overrun both their budget and time. To improve the quality of initial project plans, we show in this paper the importance of (1) reflecting features’ priorities/risk in task schedules and (2) considering uncertainties related to human factors in plan schedules. To make simulation tasks reflect features....... By comparing EPS to classical schedules, EPS simulation provides more accurate results with regards to project goals. These instructions give you guidelines for preparing papers for Journal of Software (JSW). Use this document as a template if you are using Microsoft Word 6.0 or later. Otherwise, use...

  13. Projective simulation with generalization.

    Science.gov (United States)

    Melnikov, Alexey A; Makmal, Adi; Dunjko, Vedran; Briegel, Hans J

    2017-10-31

    The ability to generalize is an important feature of any intelligent agent. Not only because it may allow the agent to cope with large amounts of data, but also because in some environments, an agent with no generalization capabilities cannot learn. In this work we outline several criteria for generalization, and present a dynamic and autonomous machinery that enables projective simulation agents to meaningfully generalize. Projective simulation, a novel, physical approach to artificial intelligence, was recently shown to perform well in standard reinforcement learning problems, with applications in advanced robotics as well as quantum experiments. Both the basic projective simulation model and the presented generalization machinery are based on very simple principles. This allows us to provide a full analytical analysis of the agent's performance and to illustrate the benefit the agent gains by generalizing. Specifically, we show that already in basic (but extreme) environments, learning without generalization may be impossible, and demonstrate how the presented generalization machinery enables the projective simulation agent to learn.

  14. A Projection Quality-Driven Tube Current Modulation Method in Cone-Beam CT for IGRT: Proof of Concept.

    Science.gov (United States)

    Men, Kuo; Dai, Jianrong

    2017-12-01

    To develop a projection quality-driven tube current modulation method in cone-beam computed tomography for image-guided radiotherapy based on the prior attenuation information obtained by the planning computed tomography and then evaluate its effect on a reduction in the imaging dose. The QCKV-1 phantom with different thicknesses (0-400 mm) of solid water upon it was used to simulate different attenuation (μ). Projections were acquired with a series of tube current-exposure time product (mAs) settings, and a 2-dimensional contrast to noise ratio was analyzed for each projection to create a lookup table of mAs versus 2-dimensional contrast to noise ratio, μ. Before a patient underwent computed tomography, the maximum attenuation [Formula: see text] within the 95% range of each projection angle (θ) was estimated according to the planning computed tomography images. Then, a desired 2-dimensional contrast to noise ratio value was selected, and the mAs setting at θ was calculated with the lookup table of mAs versus 2-dimensional contrast to noise ratio,[Formula: see text]. Three-dimensional cone-beam computed tomography images were reconstructed using the projections acquired with the selected mAs. The imaging dose was evaluated with a polymethyl methacrylate dosimetry phantom in terms of volume computed tomography dose index. Image quality was analyzed using a Catphan 503 phantom with an oval body annulus and a pelvis phantom. For the Catphan 503 phantom, the cone-beam computed tomography image obtained by the projection quality-driven tube current modulation method had a similar quality to that of conventional cone-beam computed tomography . However, the proposed method could reduce the imaging dose by 16% to 33% to achieve an equivalent contrast to noise ratio value. For the pelvis phantom, the structural similarity index was 0.992 with a dose reduction of 39.7% for the projection quality-driven tube current modulation method. The proposed method could reduce the

  15. A simplified approach for the generation of projection data for cone ...

    Indian Academy of Sciences (India)

    To test a developed reconstruction algorithm for cone beam geometry, whether it is transmission or emission tomography, one needs projection data. Generally, mathematical phantoms are generated in three dimensions and the projection for all rotation angles is calculated. For non-symmetric objects, the process is ...

  16. Monte-Carlo Simulation of Hydrogen Adsorption in Single-Wall Carbon Nano-Cones

    Directory of Open Access Journals (Sweden)

    Zohreh Ahadi

    2011-01-01

    Full Text Available The properties of hydrogen adsorption in single-walled carbon nano-cones are investigated in detail by Monte Carlo simulations. A great deal of our computational results show that the hydrogen storage capacity in single-walled carbon nano-cones is slightly smaller than the capacity of single-walled carbon nanotubes at any time at the same conditions. This indicates that the hydrogen storage capacity of single-walled carbon nano-cones is related to angles of carbon nano-cones. It seems that these type of nanotubes could not exceed the 2010 goal of 6 wt%, which is presented by the U.S. Department of Energy. In addition, these results are discussed in theory.

  17. Cone penetration and bevameter geotechnical tests in lunar regolith simulants: discrete element method analysis and experimentation

    Science.gov (United States)

    Kulchitsky, A. V.; Johnson, J.; Duvoy, P.; Wilkinson, A.; Creager, C. M.

    2012-12-01

    For in situ resource utilization on the Moon, asteroids, Mars, or other space body it is necessary to be able to simulate the interaction of mobile platforms and excavation machines with the regolith for engineering design, planning, and operations. For accurate simulations, tools designed to measure regolith properties will need to be deployed and interpreted. Two such tools are the penetrometer, used to measure a soil strength index as a function of depth, and the bevameter, used to characterize regolith surface properties of strength, friction and sinkage. The penetrometer interrogates regolith properties from the surface to a depth limited only by the capabilities of the instrument to penetrate the regolith while a bevameter interrogates only the upper few centimeters needed to describe a mobility platform's traction and sinkage. Interpretation of penetrometer and bevameter data can be difficult, especially on low gravity objects. We use the discrete element method (DEM) model to simulate the large regolith deformations and failures associated with the tests to determine regolith properties. The DEM simulates granular material behavior using large aggregates of distinct particles. Realistic physics of particle-particle interaction introduces many granular specific phenomena such as interlocking and force chain formation that cannot be represented using continuum methods. In this work, experiments using a cone penetrometer test (CPT) and bevameter on lunar simulants JSC-1A and GRC-1 were performed at NASA Glenn Research Center. These tests were used to validate the physics in the COUPi DEM model. COUPi is a general physical DEM code being developed to model machine/regolith interactions as part of a NASA Lunar Science Institute sponsored project on excavation and mobility modeling. The experimental results were used in this work to build an accurate model to simulate the lunar regolith. The CPT consists of driving an instrumented cone with opening angle of 60

  18. Numerical simulation of axisymmetric valve operation for different outer cone angle

    Science.gov (United States)

    Smyk, Emil

    One of the method of flow separation control is application of axisymmetric valve. It is composed of nozzle with core. Normally the main flow is attached to inner cone and flow by preferential collector to primary flow pipe. If through control nozzle starts flow jet (control jet) the main flow is switched to annular secondary collector. In both situation the main flow is deflected to inner or outer cone (placed at the outlet of the valve's nozzle) by Coanda effect. The paper deals with the numerical simulation of this axisymetric annular nozzle with integrated synthetic jet actuator. The aim of the work is influence examination of outer cone angle on deflection on main stream.

  19. Multi Dark Lens Simulations: weak lensing light-cones and data base presentation

    Science.gov (United States)

    Giocoli, Carlo; Jullo, Eric; Metcalf, R. Benton; de la Torre, Sylvain; Yepes, Gustavo; Prada, Francisco; Comparat, Johan; Göttlober, Stefan; Kyplin, Anatoly; Kneib, Jean-Paul; Petkova, Margarita; Shan, Huan Yuan; Tessore, Nicolas

    2016-09-01

    In this paper we present a large data base of weak lensing light cones constructed using different snapshots from the Big MultiDark simulation (BigMDPL). The ray-tracing through different multiple plane has been performed with the GLAMER code accounting both for single source redshifts and for sources distributed along the cosmic time. This first paper presents weak lensing forecasts and results according to the geometry of the VIPERS-W1 and VIPERS-W4 field of view. Additional fields will be available on our data base and new ones can be run upon request. Our data base also contains some tools for lensing analysis. In this paper we present results for convergence power spectra, one point and high order weak lensing statistics useful for forecasts and for cosmological studies. Covariance matrices have also been computed for the different realizations of the W1 and W4 fields. In addition we compute also galaxy-shear and projected density contrasts for different halo masses at two lens redshift according to the CFHTLS source redshift distribution both using stacking and cross-correlation techniques, finding very good agreement.

  20. Automatic tracking of implanted fiducial markers in cone beam CT projection images

    OpenAIRE

    Marchant, T.E.; Skalski, A.; Matuszewski, B. J.

    2012-01-01

    Purpose: This paper describes a novel method for simultaneous intrafraction tracking of multiple fiducial markers. Although the proposed method is generic and can be adopted for a number of applications including fluoroscopy based patient position monitoring and gated radiotherapy, the tracking results presented in this paper are specific to tracking fiducial markers in a sequence of cone beam CT projection images. Methods: The proposed method is accurate and robust thanks to utilizing the me...

  1. Cone-beam CT in paediatric dentistry: DIMITRA project position statement.

    Science.gov (United States)

    Oenning, Anne Caroline; Jacobs, Reinhilde; Pauwels, Ruben; Stratis, Andreas; Hedesiu, Mihaela; Salmon, Benjamin

    2018-03-01

    DIMITRA (dentomaxillofacial paediatric imaging: an investigation towards low-dose radiation induced risks) is a European multicenter and multidisciplinary project focused on optimizing cone-beam CT exposures for children and adolescents. With increasing use of cone-beam CT for dentomaxillofacial diagnostics, concern arises regarding radiation risks associated with this imaging modality, especially for children. Research evidence concerning cone-beam CT indications in children remains limited, while reports mention inconsistent recommendations for dose reduction. Furthermore, there is no paper using the combined and integrated information on the required indication-oriented image quality and the related patient dose levels. In this paper, therefore, the authors initiate an integrated approach based on current evidence regarding image quality and dose, together with the expertise of DIMITRA's members searching for a state of the art. The aim of this DIMITRA position statement is to provide indication-oriented and patient-specific recommendations regarding the main cone-beam CT applications in the pediatric field. The authors will review this position statement document when results regarding multidisciplinary approaches evolve, in a period of 5 years or earlier.

  2. Projective simulation for artificial intelligence

    Science.gov (United States)

    Briegel, Hans J.; de Las Cuevas, Gemma

    2012-05-01

    We propose a model of a learning agent whose interaction with the environment is governed by a simulation-based projection, which allows the agent to project itself into future situations before it takes real action. Projective simulation is based on a random walk through a network of clips, which are elementary patches of episodic memory. The network of clips changes dynamically, both due to new perceptual input and due to certain compositional principles of the simulation process. During simulation, the clips are screened for specific features which trigger factual action of the agent. The scheme is different from other, computational, notions of simulation, and it provides a new element in an embodied cognitive science approach to intelligent action and learning. Our model provides a natural route for generalization to quantum-mechanical operation and connects the fields of reinforcement learning and quantum computation.

  3. Projective multiplets and hyperkähler cones in conformal supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Butter, Daniel [Nikhef Theory Group, Science Park 105, 1098 XG Amsterdam (Netherlands)

    2015-06-24

    Projective superspace provides a natural framework for the construction of actions coupling hypermultiplets to conformal supergravity. We review how the off-shell actions are formulated in superspace and then discuss how to eliminate the infinite number of auxiliary fields to produce an on-shell N=2 supersymmetric sigma model, with the target space corresponding to a generic 4n-dimensional hyperkähler cone. We show how the component action coupling the hypermultiplets to conformal supergravity may be constructed starting from curved superspace. The superspace origin of the geometric data — the hyperkähler potential, complex structures, and any gauged isometries — is also addressed.

  4. Calculating tumor trajectory and dose-of-the-day using cone-beam CT projections

    CERN Document Server

    Jones, Bernard L; Miften, Moyed

    2015-01-01

    Purpose: Cone-beam CT (CBCT) projection images provide anatomical data in real-time over several respiratory cycles, forming a comprehensive picture of tumor movement. We developed and validated a method which uses these projections to determine the trajectory of and dose to highly mobile tumors during each fraction of treatment. Methods: CBCT images of a respiration phantom were acquired, the trajectory of which mimicked a lung tumor with high amplitude (up to 2.5 cm) and hysteresis. A template-matching algorithm was used to identify the location of a steel BB in each CBCT projection, and a Gaussian probability density function for the absolute BB position was calculated which best fit the observed trajectory of the BB in the imager geometry. Two modifications of the trajectory reconstruction were investigated: first, using respiratory phase information to refine the trajectory estimation (Phase), and second, using the Monte Carlo (MC) method to sample the estimated Gaussian tumor position distribution. Resu...

  5. Simulation of Cone Beam CT System Based on Monte Carlo Method

    OpenAIRE

    Wang, Yu; Chen, Chaobin; Cao, Ruifen; Hu, Liqin; Li, Bingbing

    2014-01-01

    Adaptive Radiation Therapy (ART) was developed based on Image-guided Radiation Therapy (IGRT) and it is the trend of photon radiation therapy. To get a better use of Cone Beam CT (CBCT) images for ART, the CBCT system model was established based on Monte Carlo program and validated against the measurement. The BEAMnrc program was adopted to the KV x-ray tube. Both IOURCE-13 and ISOURCE-24 were chosen to simulate the path of beam particles. The measured Percentage Depth Dose (PDD) and lateral ...

  6. Assessment of simulated mandibular condyle bone lesions by cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Alexandre Perez; Perrella, Andreia; Arita, Emiko Saito; Pereira, Marlene Fenyo Soeiro de Matos; Cavalcanti, Marcelo de Gusmao Paraiso, E-mail: alexperez34@gmail.co [Universidade de Sao Paulo (USP), SP (Brazil). Faculdade de Odontologia. Dept. de Estomatologia

    2010-10-15

    There are many limitations to image acquisition, using conventional radiography, of the temporomandibular joint (TMJ) region. The Computed Tomography (CT) scan is a better option, due to its higher accuracy, for purposes of diagnosis, surgical planning and treatment of bone injuries. The aim of the present study was to analyze two protocols of cone beam computed tomography for the evaluation of simulated mandibular condyle bone lesions. Spherical lesions were simulated in 30 dry mandibular condyles, using dentist drills and drill bits sizes 1, 3 and 6. Each of the mandibular condyles was submitted to cone beam computed tomography (CBCT) using two protocols: axial, coronal and sagittal multiplanar reconstruction (MPR); and sagittal plus coronal slices throughout the longitudinal axis of the mandibular condyles. For these protocols, 2 observers analyzed the CBCT images independently, regarding the presence or not of injuries. Only one of the observers, however, performed on 2 different occasions. The results were compared to the gold standard, evaluating the percentage of agreement, degree of accuracy of CBCT protocols and observers' examination. The z test was used for the statistical analysis. The results showed there were no statistically significant differences between the 2 protocols. There was greater difficulty in the assessment of small-size simulated lesions (drill no.1). From the results of this study, it can be concluded that CBCT is an accurate tool for analyzing mandibular condyle bone lesions, with the MPR protocol showing slightly better results than the sagittal plus coronal slices throughout the longitudinal axis. (author)

  7. Image artifacts and noise reduction algorithm for cone-beam computed tomography with low-signal projections.

    Science.gov (United States)

    Yang, Fu-Qiang; Zhang, Ding-Hua; Huang, Kui-Dong; Yang, Ya-Fei; Liao, Jin-Ming

    2017-10-10

    This study aims to investigate and test a new image reconstruction algorithm applying to the low-signal projections to generate high quality images by reducing the artifacts and noise in the cone-beam computed tomography (CBCT). For the low-signal and noisy projections, a multiple sampling method is first utilized in projection domain to suppress environmental noise, which guarantees the accuracy of the data for reconstruction, simultaneously. Next, a fuzzy entropy based method with block matching 3D (BM3D) filtering algorithm is employed to improve the image quality to reduce artifacts and noise in image domain. Then, simulation studies on polychromatic spectrum were performed to evaluate the performance of the proposed new algorithm. Study results demonstrated significant improvement in the signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of the images reconstructed using the new algorithm. SNRs and CNRs of the new images were averagely 40% and 20% higher than those of the previous images reconstructed using the traditional algorithms, respectively. As a result, since the new image reconstruction algorithm effectively reduced the artifacts and noise, and produced images with better contour and grayscale distribution, it has the potential to improve image quality using the original CBCT data with the low and missing signals.

  8. Fusion Simulation Project Workshop Report

    Science.gov (United States)

    Kritz, Arnold; Keyes, David

    2009-03-01

    The mission of the Fusion Simulation Project is to develop a predictive capability for the integrated modeling of magnetically confined plasmas. This FSP report adds to the previous activities that defined an approach to integrated modeling in magnetic fusion. These previous activities included a Fusion Energy Sciences Advisory Committee panel that was charged to study integrated simulation in 2002. The report of that panel [Journal of Fusion Energy 20, 135 (2001)] recommended the prompt initiation of a Fusion Simulation Project. In 2003, the Office of Fusion Energy Sciences formed a steering committee that developed a project vision, roadmap, and governance concepts [Journal of Fusion Energy 23, 1 (2004)]. The current FSP planning effort involved 46 physicists, applied mathematicians and computer scientists, from 21 institutions, formed into four panels and a coordinating committee. These panels were constituted to consider: Status of Physics Components, Required Computational and Applied Mathematics Tools, Integration and Management of Code Components, and Project Structure and Management. The ideas, reported here, are the products of these panels, working together over several months and culminating in a 3-day workshop in May 2007.

  9. TH-A-18C-09: Ultra-Fast Monte Carlo Simulation for Cone Beam CT Imaging of Brain Trauma

    Energy Technology Data Exchange (ETDEWEB)

    Sisniega, A; Zbijewski, W; Stayman, J [Department of Biomedical Engineering, Johns Hopkins University (United States); Yorkston, J [Carestream Health (United States); Aygun, N [Department of Radiology, Johns Hopkins University (United States); Koliatsos, V [Department of Neurology, Johns Hopkins University (United States); Siewerdsen, J [Department of Biomedical Engineering, Johns Hopkins University (United States); Department of Radiology, Johns Hopkins University (United States)

    2014-06-15

    Purpose: Application of cone-beam CT (CBCT) to low-contrast soft tissue imaging, such as in detection of traumatic brain injury, is challenged by high levels of scatter. A fast, accurate scatter correction method based on Monte Carlo (MC) estimation is developed for application in high-quality CBCT imaging of acute brain injury. Methods: The correction involves MC scatter estimation executed on an NVIDIA GTX 780 GPU (MC-GPU), with baseline simulation speed of ~1e7 photons/sec. MC-GPU is accelerated by a novel, GPU-optimized implementation of variance reduction (VR) techniques (forced detection and photon splitting). The number of simulated tracks and projections is reduced for additional speed-up. Residual noise is removed and the missing scatter projections are estimated via kernel smoothing (KS) in projection plane and across gantry angles. The method is assessed using CBCT images of a head phantom presenting a realistic simulation of fresh intracranial hemorrhage (100 kVp, 180 mAs, 720 projections, source-detector distance 700 mm, source-axis distance 480 mm). Results: For a fixed run-time of ~1 sec/projection, GPU-optimized VR reduces the noise in MC-GPU scatter estimates by a factor of 4. For scatter correction, MC-GPU with VR is executed with 4-fold angular downsampling and 1e5 photons/projection, yielding 3.5 minute run-time per scan, and de-noised with optimized KS. Corrected CBCT images demonstrate uniformity improvement of 18 HU and contrast improvement of 26 HU compared to no correction, and a 52% increase in contrast-tonoise ratio in simulated hemorrhage compared to “oracle” constant fraction correction. Conclusion: Acceleration of MC-GPU achieved through GPU-optimized variance reduction and kernel smoothing yields an efficient (<5 min/scan) and accurate scatter correction that does not rely on additional hardware or simplifying assumptions about the scatter distribution. The method is undergoing implementation in a novel CBCT dedicated to brain

  10. TH-A-18C-04: Ultrafast Cone-Beam CT Scatter Correction with GPU-Based Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y [UT Southwestern Medical Center, Dallas, TX (United States); Southern Medical University, Guangzhou (China); Bai, T [UT Southwestern Medical Center, Dallas, TX (United States); Xi' an Jiaotong University, Xi' an (China); Yan, H; Ouyang, L; Wang, J; Pompos, A; Jiang, S; Jia, X [UT Southwestern Medical Center, Dallas, TX (United States); Zhou, L [Southern Medical University, Guangzhou (China)

    2014-06-15

    Purpose: Scatter artifacts severely degrade image quality of cone-beam CT (CBCT). We present an ultrafast scatter correction framework by using GPU-based Monte Carlo (MC) simulation and prior patient CT image, aiming at automatically finish the whole process including both scatter correction and reconstructions within 30 seconds. Methods: The method consists of six steps: 1) FDK reconstruction using raw projection data; 2) Rigid Registration of planning CT to the FDK results; 3) MC scatter calculation at sparse view angles using the planning CT; 4) Interpolation of the calculated scatter signals to other angles; 5) Removal of scatter from the raw projections; 6) FDK reconstruction using the scatter-corrected projections. In addition to using GPU to accelerate MC photon simulations, we also use a small number of photons and a down-sampled CT image in simulation to further reduce computation time. A novel denoising algorithm is used to eliminate MC scatter noise caused by low photon numbers. The method is validated on head-and-neck cases with simulated and clinical data. Results: We have studied impacts of photo histories, volume down sampling factors on the accuracy of scatter estimation. The Fourier analysis was conducted to show that scatter images calculated at 31 angles are sufficient to restore those at all angles with <0.1% error. For the simulated case with a resolution of 512×512×100, we simulated 10M photons per angle. The total computation time is 23.77 seconds on a Nvidia GTX Titan GPU. The scatter-induced shading/cupping artifacts are substantially reduced, and the average HU error of a region-of-interest is reduced from 75.9 to 19.0 HU. Similar results were found for a real patient case. Conclusion: A practical ultrafast MC-based CBCT scatter correction scheme is developed. The whole process of scatter correction and reconstruction is accomplished within 30 seconds. This study is supported in part by NIH (1R01CA154747-01), The Core Technology Research

  11. The effects of simulated vision impairments on the cone of gaze.

    Science.gov (United States)

    Hecht, Heiko; Hörichs, Jenny; Sheldon, Sarah; Quint, Jessilin; Bowers, Alex

    2015-10-01

    Detecting the gaze direction of others is critical for many social interactions. We explored factors that may make the perception of mutual gaze more difficult, including the degradation of the stimulus and simulated vision impairment. To what extent do these factors affect the complex assessment of mutual gaze? Using an interactive virtual head whose eye direction could be manipulated by the subject, we conducted two experiments to assess the effects of simulated vision impairments on mutual gaze. Healthy subjects had to demarcate the center and the edges of the cone of gaze-that is, the range of gaze directions that are accepted for mutual gaze. When vision was impaired by adding a semitransparent white contrast reduction mask to the display (Exp. 1), judgments became more variable and more influenced by the head direction (indicative of a compensation strategy). When refractive blur was added (Exp. 1), the gaze cone shrank from 12.9° (no blur) to 11.3° (3-diopter lens), which cannot be explained by a low-level process but might reflect a tightening of the criterion for mutual gaze as a response to the increased uncertainty. However, the overall effects of the impairments were relatively modest. Elderly subjects (Exp. 2) produced more variability but did not differ qualitatively from the younger subjects. In the face of artificial vision impairments, compensation mechanisms and criterion changes allow us to perform better in mutual gaze perception than would be predicted by a simple extrapolation from the losses in basic visual acuity and contrast sensitivity.

  12. The ability of cone-beam computed tomography to detect simulated buccal and lingual recesses in root canals

    NARCIS (Netherlands)

    Liang, Y.H.; Yuan, M.; Li, G.; Shemesh, H.; Wesselink, P.R.; Wu, M.K.

    2012-01-01

    Aim  To compare the ability of cone-beam computed tomography (CBCT) and digital periapical radiographs (PR) to detect simulated tissue-occupied recesses in root canals. Methodology  A standard canal was created in 30 extracted mandibular premolar roots. Each root was longitudinally split into buccal

  13. The Mars Gravity Simulation Project

    Science.gov (United States)

    Korienek, Gene

    1998-10-01

    Human beings who make abrupt transitions between one gravitational environment and another undergo severe disruptions of their visual perception and visual- motor coordination, frequently accompanied by "space sickness." Clearly, such immediate effects of exposure to a novel gravitational condition have significant implications for human performance. For example, when astronauts first arrive in Earth orbit their attempts to move about in the spacecraft and to perform their duties are uncoordinated, inaccurate, and inefficient. Other inter-gravitational transitions for which these difficulties can be expected include going from the 0 g of the spacecraft to the. 16 g of the Moon, from 0 g to the .38 g of Mars, and from 0 g back to the 1.0 g of Earth. However, after astronauts have actively interacted with their new gravitational environment for several days, these problems tend to disappear, evidence that some sort of adaptive process has taken place. It would be advantageous, therefore, if there were some way to minimize or perhaps even to eliminate this potentially hazardous adaptive transition period by allowing astronauts to adapt to the altered gravitational conditions before actually entering them. Simultaneous adaptations to both the altered and the normal gravitational environment as a result of repeatedly adapting to one and readapting to the other, a phenomenon known as dual adaptation. The objective of the Mars Gravity Simulator (MGS) Project is to construct a simulation of the visual and bodily effects of altered gravity. This perceptual-motor simulation is created through the use of: 1) differential body pressure to produce simulated hypo-gravity and 2) treadmill-controlled virtual reality to create a corresponding visual effect. It is expected that this combination will produce sensory motor perturbations in the subjects. Both the immediate and adaptive behavioral (postural and ambulatory) responses to these sensory perturbations will be assessed.

  14. Grid generation and adaptation for the Direct Simulation Monte Carlo Method. [for complex flows past wedges and cones

    Science.gov (United States)

    Olynick, David P.; Hassan, H. A.; Moss, James N.

    1988-01-01

    A grid generation and adaptation procedure based on the method of transfinite interpolation is incorporated into the Direct Simulation Monte Carlo Method of Bird. In addition, time is advanced based on a local criterion. The resulting procedure is used to calculate steady flows past wedges and cones. Five chemical species are considered. In general, the modifications result in a reduced computational effort. Moreover, preliminary results suggest that the simulation method is time step dependent if requirements on cell sizes are not met.

  15. Lung tumor tracking, trajectory reconstruction, and motion artifact removal using rotational cone-beam projections

    Science.gov (United States)

    Lewis, John Henry

    Management of lung tumor motion is a challenging and important problem for modern, highly conformal radiotherapy. Poorly managed tumor motion can lead to imaging artifacts, poor target coverage, and unnecessarily high dose to normal tissues. The goals of this dissertation are to develop a real-time localization algorithm that is applicable to rotational cone-beam projections acquired during regular (˜60 seconds) cone-beam computed tomography (CBCT) scans, and to use these tracking results to reconstruct a tumor's trajectory, shape and size immediately prior to treatment. Direct tumor tracking is performed via a multiple template matching algorithm where templates are derived from digitally reconstructed radiographs (DRRs) generated from four-dimensional computed tomography (4DCT). Three-dimensional (3D) tumor trajectories are reconstructed by binning twodimensional (2D) tracking results according to their corresponding respiratory phases. Within each phase bin a point is calculated approximating the 3D tumor position, resulting in a 3D phase-binned trajectory. These 3D trajectories are used to construct motion blurring functions which are in turn used to remove motion blurring artifacts from reconstructed CBCT volumes with a deconvolution algorithm. Finally, the initial direct tracking algorithm is combined with diaphragm-based tracking to develop a more robust "combined" tracking algorithm. Respiratory motion phantoms (digital and physical), and example patient cases were used to test each technique. Direct tumor tracking performed well for both phantom cases, with sub-millimeter root mean square error (e rms) in the axial and tangential imager dimensions. In patient studies the algorithm performed well for many angles, but exhibited large errors for some projections. Accurate 3D trajectories were successfully reconstructed for patients and phantoms. Errors in reconstructed trajectories were smaller than the errors in the direct tracking results in all cases. The

  16. Radiation doses in cone-beam breast computed tomography: A Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Yi Ying; Lai, Chao-Jen; Han Tao; Zhong Yuncheng; Shen Youtao; Liu Xinming; Ge Shuaiping; You Zhicheng; Wang Tianpeng; Shaw, Chris C. [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    2011-02-15

    Purpose: In this article, we describe a method to estimate the spatial dose variation, average dose and mean glandular dose (MGD) for a real breast using Monte Carlo simulation based on cone beam breast computed tomography (CBBCT) images. We present and discuss the dose estimation results for 19 mastectomy breast specimens, 4 homogeneous breast models, 6 ellipsoidal phantoms, and 6 cylindrical phantoms. Methods: To validate the Monte Carlo method for dose estimation in CBBCT, we compared the Monte Carlo dose estimates with the thermoluminescent dosimeter measurements at various radial positions in two polycarbonate cylinders (11- and 15-cm in diameter). Cone-beam computed tomography (CBCT) images of 19 mastectomy breast specimens, obtained with a bench-top experimental scanner, were segmented and used to construct 19 structured breast models. Monte Carlo simulation of CBBCT with these models was performed and used to estimate the point doses, average doses, and mean glandular doses for unit open air exposure at the iso-center. Mass based glandularity values were computed and used to investigate their effects on the average doses as well as the mean glandular doses. Average doses for 4 homogeneous breast models were estimated and compared to those of the corresponding structured breast models to investigate the effect of tissue structures. Average doses for ellipsoidal and cylindrical digital phantoms of identical diameter and height were also estimated for various glandularity values and compared with those for the structured breast models. Results: The absorbed dose maps for structured breast models show that doses in the glandular tissue were higher than those in the nearby adipose tissue. Estimated average doses for the homogeneous breast models were almost identical to those for the structured breast models (p=1). Normalized average doses estimated for the ellipsoidal phantoms were similar to those for the structured breast models (root mean square (rms

  17. A practical cone-beam CT scatter correction method with optimized Monte Carlo simulations for image-guided radiation therapy

    Science.gov (United States)

    Xu, Yuan; Bai, Ti; Yan, Hao; Ouyang, Luo; Pompos, Arnold; Wang, Jing; Zhou, Linghong; Jiang, Steve B.; Jia, Xun

    2015-05-01

    Cone-beam CT (CBCT) has become the standard image guidance tool for patient setup in image-guided radiation therapy. However, due to its large illumination field, scattered photons severely degrade its image quality. While kernel-based scatter correction methods have been used routinely in the clinic, it is still desirable to develop Monte Carlo (MC) simulation-based methods due to their accuracy. However, the high computational burden of the MC method has prevented routine clinical application. This paper reports our recent development of a practical method of MC-based scatter estimation and removal for CBCT. In contrast with conventional MC approaches that estimate scatter signals using a scatter-contaminated CBCT image, our method used a planning CT image for MC simulation, which has the advantages of accurate image intensity and absence of image truncation. In our method, the planning CT was first rigidly registered with the CBCT. Scatter signals were then estimated via MC simulation. After scatter signals were removed from the raw CBCT projections, a corrected CBCT image was reconstructed. The entire workflow was implemented on a GPU platform for high computational efficiency. Strategies such as projection denoising, CT image downsampling, and interpolation along the angular direction were employed to further enhance the calculation speed. We studied the impact of key parameters in the workflow on the resulting accuracy and efficiency, based on which the optimal parameter values were determined. Our method was evaluated in numerical simulation, phantom, and real patient cases. In the simulation cases, our method reduced mean HU errors from 44 to 3 HU and from 78 to 9 HU in the full-fan and the half-fan cases, respectively. In both the phantom and the patient cases, image artifacts caused by scatter, such as ring artifacts around the bowtie area, were reduced. With all the techniques employed, we achieved computation time of less than 30 s including the

  18. Influence of Cone-Beam Computed Tomography filters on diagnosis of simulated endodontic complications.

    Science.gov (United States)

    Verner, F S; D'Addazio, P S; Campos, C N; Devito, K L; Almeida, S M; Junqueira, R B

    2017-11-01

    To evaluate the influence of cone-beam computed tomography (CBCT) filters on diagnosis of simulated endodontic complications. Sixteen human teeth, in three mandibles, were submitted to the following simulated endodontic complications: (G1) fractured file, (G2) perforations in the canal walls, (G3) deviated cast post, and (G4) external root resorption. The mandibles were submitted to CBCT examination (I-Cat® Next Generation). Five oral radiologists evaluated the images independently with and without XoranCat® software filters. Accuracy, sensitivity and specificity were determined. ROC curves were calculated for each group with the filters, and the areas under the curves were compared using anova (one-way) test. McNemar test was applied for pair-wise agreement between all images versus the gold standard and original images versus images with filters (P endodontic complication to diagnosis, followed by G2, G4 and G3. There were no differences between areas under the ROC curves for the filters in all groups; however, Sharpen Super Mild filter had the best results for G1 (0.47), Angio Sharpen Low 3 × 3 for G2 (0.93), Angio Sharpen Low 3 × 3, S9, Shadow and Sharpen for G3 (1.00) and Sharpen 3 × 3 for G4 (1.00). The McNemar test revealed significant differences between all filters with the gold standard (P = 0.00 for all filters) and the originals images (P = 0.00 for all filters) only in G1 group. There were no differences in the other groups. The filters did not improve the diagnosis of the simulated endodontic complications evaluated. Their diagnosis remains a major challenge in clinical practice. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  19. Use of Monte Carlo simulation software for calculating effective dose in cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Gomes B, W. O., E-mail: wilsonottobatista@gmail.com [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho 40301-015, Salvador de Bahia (Brazil)

    2016-10-15

    This study aimed to develop a geometry of irradiation applicable to the software PCXMC and the consequent calculation of effective dose in applications of the Computed Tomography Cone Beam (CBCT). We evaluated two different CBCT equipment s for dental applications: Care stream Cs 9000 3-dimensional tomograph; i-CAT and GENDEX GXCB-500. Initially characterize each protocol measuring the surface kerma input and the product kerma air-area, P{sub KA}, with solid state detectors RADCAL and PTW transmission chamber. Then we introduce the technical parameters of each preset protocols and geometric conditions in the PCXMC software to obtain the values of effective dose. The calculated effective dose is within the range of 9.0 to 15.7 μSv for 3-dimensional computer 9000 Cs; within the range 44.5 to 89 μSv for GXCB-500 equipment and in the range of 62-111 μSv for equipment Classical i-CAT. These values were compared with results obtained dosimetry using TLD implanted in anthropomorphic phantom and are considered consistent. Os effective dose results are very sensitive to the geometry of radiation (beam position in mathematical phantom). This factor translates to a factor of fragility software usage. But it is very useful to get quick answers to regarding process optimization tool conclusions protocols. We conclude that use software PCXMC Monte Carlo simulation is useful assessment protocols for CBCT tests in dental applications. (Author)

  20. 3D localization of electrophysiology catheters from a single x-ray cone-beam projection

    Energy Technology Data Exchange (ETDEWEB)

    Robert, Normand, E-mail: normand.robert@sri.utoronto.ca; Polack, George G.; Sethi, Benu; Rowlands, John A. [Physical Sciences, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Crystal, Eugene [Division of Cardiology, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)

    2015-10-15

    Purpose: X-ray images allow the visualization of percutaneous devices such as catheters in real time but inherently lack depth information. The provision of 3D localization of these devices from cone beam x-ray projections would be advantageous for interventions such as electrophysiology (EP), whereby the operator needs to return a device to the same anatomical locations during the procedure. A method to achieve real-time 3D single view localization (SVL) of an object of known geometry from a single x-ray image is presented. SVL exploits the change in the magnification of an object as its distance from the x-ray source is varied. The x-ray projection of an object of interest is compared to a synthetic x-ray projection of a model of said object as its pose is varied. Methods: SVL was tested with a 3 mm spherical marker and an electrophysiology catheter. The effect of x-ray acquisition parameters on SVL was investigated. An independent reference localization method was developed to compare results when imaging a catheter translated via a computer controlled three-axes stage. SVL was also performed on clinical fluoroscopy image sequences. A commercial navigation system was used in some clinical image sequences for comparison. Results: SVL estimates exhibited little change as x-ray acquisition parameters were varied. The reproducibility of catheter position estimates in phantoms denoted by the standard deviations, (σ{sub x}, σ{sub y}, σ{sub z}) = (0.099 mm,  0.093 mm,  2.2 mm), where x and y are parallel to the detector plane and z is the distance from the x-ray source. Position estimates (x, y, z) exhibited a 4% systematic error (underestimation) when compared to the reference method. The authors demonstrated that EP catheters can be tracked in clinical fluoroscopic images. Conclusions: It has been shown that EP catheters can be localized in real time in phantoms and clinical images at fluoroscopic exposure rates. Further work is required to characterize

  1. Numerical Simulations of Hollow Cone Injection and Gasoline Compression Ignition Combustion With Naphtha Fuels

    KAUST Repository

    Badra, Jihad A.

    2016-01-11

    Gasoline compression ignition (GCI), also known as partially premixed compression ignition (PPCI) and gasoline direct injection compression ignition (GDICI), engines have been considered an attractive alternative to traditional spark ignition engines. Lean burn combustion with the direct injection of fuel eliminates throttle losses for higher thermodynamic efficiencies, and the precise control of the mixture compositions allows better emission performance such as NOx and particulate matter (PM). Recently, low octane gasoline fuel has been identified as a viable option for the GCI engine applications due to its longer ignition delay characteristics compared to diesel and lighter evaporation compared to gasoline fuel [1]. The feasibility of such a concept has been demonstrated by experimental investigations at Saudi Aramco [1, 2]. The present study aims to develop predictive capabilities for low octane gasoline fuel compression ignition engines with accurate characterization of the spray dynamics and combustion processes. Full three-dimensional simulations were conducted using CONVERGE as a basic modeling framework, using Reynolds-averaged Navier-Stokes (RANS) turbulent mixing models. An outwardly opening hollow-cone spray injector was characterized and validated against existing and new experimental data. An emphasis was made on the spray penetration characteristics. Various spray breakup and collision models have been tested and compared with the experimental data. An optimum combination has been identified and applied in the combusting GCI simulations. Linear instability sheet atomization (LISA) breakup model and modified Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) break models proved to work the best for the investigated injector. Comparisons between various existing spray models and a parametric study have been carried out to study the effects of various spray parameters. The fuel effects have been tested by using three different primary reference fuel (PRF

  2. Automated patient setup and gating using cone beam computed tomography projections

    Science.gov (United States)

    Wan, Hanlin; Bertholet, Jenny; Ge, Jiajia; Poulsen, Per; Parikh, Parag

    2016-03-01

    In radiation therapy, fiducial markers are often implanted near tumors and used for patient positioning and respiratory gating purposes. These markers are then used to manually align the patients by matching the markers in the cone beam computed tomography (CBCT) reconstruction to those in the planning CT. This step is time-intensive and user-dependent, and often results in a suboptimal patient setup. We propose a fully automated, robust method based on dynamic programming (DP) for segmenting radiopaque fiducial markers in CBCT projection images, which are then used to automatically optimize the treatment couch position and/or gating window bounds. The mean of the absolute 2D segmentation error of our DP algorithm is 1.3+/- 1.0 mm for 87 markers on 39 patients. Intrafraction images were acquired every 3 s during treatment at two different institutions. For gated patients from Institution A (8 patients, 40 fractions), the DP algorithm increased the delivery accuracy (96+/- 6% versus 91+/- 11% , p  manual setup using kV fluoroscopy. For non-gated patients from Institution B (6 patients, 16 fractions), the DP algorithm performed similarly (1.5+/- 0.8 mm versus 1.6+/- 0.9 mm, p  =  0.48) compared to the manual setup matching the fiducial markers in the CBCT to the mean position. Our proposed automated patient setup algorithm only takes 1-2 s to run, requires no user intervention, and performs as well as or better than the current clinical setup.

  3. A Simple Scatter Reduction Method in Cone-Beam Computed Tomography for Dental and Maxillofacial Applications Based on Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    Chalinee Thanasupsombat

    2018-01-01

    Full Text Available The quality of images obtained from cone-beam computed tomography (CBCT is important in diagnosis and treatment planning for dental and maxillofacial applications. However, X-ray scattering inside a human head is one of the main factors that cause a drop in image quality, especially in the CBCT system with a wide-angle cone-beam X-ray source and a large area detector. In this study, the X-ray scattering distribution within a standard head phantom was estimated using the Monte Carlo method based on Geant4. Due to small variation of low-frequency scattering signals, the scattering signals from the head phantom can be represented as the simple predetermined scattering signals from a patient’s head and subtracted the projection data for scatter reduction. The results showed higher contrast and less cupping artifacts on the reconstructed images of the head phantom and real patients. Furthermore, the same simulated scattering signals can also be applied to process with higher-resolution projection data.

  4. Robotic Vehicle Proxy Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies proposes the development of a digital simulation that can replace robotic vehicles in field studies. This proxy simulation will model the...

  5. An Inter-Projection Interpolation (IPI) Approach with Geometric Model Restriction to Reduce Image Dose in Cone Beam CT (CBCT)

    Science.gov (United States)

    Zhang, Hong; Kong, Fengchong; Ren, Lei; Jin, Jian-Yue

    2015-01-01

    Cone beam computed tomography (CBCT) imaging is a key step in image guided radiation therapy (IGRT) to improve tumor targeting. The quality and imaging dose of CBCT are two important factors. However, X-ray scatter in the large cone beam field usually induces image artifacts and degrades the image quality for CBCT. A synchronized moving grid (SMOG) approach has recently been proposed to resolve this issue and shows great promise. However, the SMOG technique requires two projections in the same gantry angle to obtain full information due to signal blockage by the grid. This study aims to develop an inter-projection interpolation (IPI) method to estimate the blocked image information. This approach will require only one projection in each gantry angle, thus reducing the scan time and patient dose. IPI is also potentially suitable for sparse-view CBCT reconstruction to reduce the imaging dose. To be compared with other state-of-the-art spatial interpolation (called inpainting) methods in terms of signal-to-noise ratio (SNR) on a Catphan and head phantoms, IPI increases SNR from 15.3dB and 12.7dB to 29.0dB and 28.1dB, respectively. The SNR of IPI on sparse-view CBCT reconstruction can achieve from 28dB to 17dB for undersample projection sets with gantry angle interval varying from 1 to 3 degrees for both phantoms. PMID:26005721

  6. Numerical Simulations of Hollow-Cone Injection and Gasoline Compression Ignition Combustion With Naphtha Fuels

    KAUST Repository

    Badra, Jihad A.

    2016-01-29

    Gasoline compression ignition (GCI), also known as partially premixed compression ignition (PPCI) and gasoline direct injection compression ignition (GDICI), engines have been considered an attractive alternative to traditional spark ignition (SI) engines. Lean-burn combustion with the direct injection of fuel eliminates throttle losses for higher thermodynamic efficiencies, and the precise control of the mixture compositions allows better emission performance such as NOx and particulate matter (PM). Recently, low octane gasoline fuel has been identified as a viable option for the GCI engine applications due to its longer ignition delay characteristics compared to diesel and lighter evaporation compared to gasoline fuel (Chang et al., 2012, "Enabling High Efficiency Direct Injection Engine With Naphtha Fuel Through Partially Premixed Charge Compression Ignition Combustion," SAE Technical Paper No. 2012-01-0677). The feasibility of such a concept has been demonstrated by experimental investigations at Saudi Aramco (Chang et al., 2012, "Enabling High Efficiency Direct Injection Engine With Naphtha Fuel Through Partially Premixed Charge Compression Ignition Combustion," SAE Technical Paper No. 2012-01-0677; Chang et al., 2013, "Fuel Economy Potential of Partially Premixed Compression Ignition (PPCI) Combustion With Naphtha Fuel," SAE Technical Paper No. 2013-01-2701). The present study aims to develop predictive capabilities for low octane gasoline fuel compression ignition (CI) engines with accurate characterization of the spray dynamics and combustion processes. Full three-dimensional simulations were conducted using converge as a basic modeling framework, using Reynolds-averaged Navier-Stokes (RANS) turbulent mixing models. An outwardly opening hollow-cone spray injector was characterized and validated against existing and new experimental data. An emphasis was made on the spray penetration characteristics. Various spray breakup and collision models have been

  7. Robotic Vehicle Proxy Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies proposes the development of a digital simulation to replace robotic vehicles in field studies. It will model the dynamics, terrain interaction,...

  8. Airline Operations Center Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Airspace Systems Program (ASP) uses a large suite of models, simulations, and laboratories to develop and assess new ATM concepts and technologies. Most of...

  9. Simulation of investment returns of toll projects.

    Science.gov (United States)

    2013-08-01

    This research develops a methodological framework to illustrate key stages in applying the simulation of investment returns of toll projects, acting as an example process of helping agencies conduct numerical risk analysis by taking certain uncertain...

  10. Gas coning control for smart wells using a dynamic coupled well-reservoir simulator

    NARCIS (Netherlands)

    Leemhuis, A.P.; Nennie, E.D.; Belfroid, S.P.C.; Alberts, G.J.N.; Peters, E.; Joosten, G.J.P.

    2008-01-01

    A strong increase in gas inflow due to gas coning and the resulting bean-back because of Gas to Oil Ratio (GOR) constraints can severely limit oil production and reservoir drive energy. In this paper we will use a coupled reservoir-well model to demonstrate that oil production can be increased by

  11. Edge Simulation Laboratory Project Report

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, R. H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dorf, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dorr, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rognlien, T. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-02-25

    In 2010 The Edge Simulation Laboratory (ESL) embarked upon the plan laid out in the renewal proposal submitted in December 2009. This proposal called for initially parallel efforts addressing the physics of the closed-flux-surface pedestal region, using existing computational tools (GYRO, BOUT++) and analytic modeling, and physics of the scrape-off layer via development of the new edge gyrokinetic code COGENT. Progress in the former area is described in a series of monthly progress reports prepared by General Atomics; these are attached as a set of appendices (describing work done in the month prior to the indicated date). Progress in the latter area, as well as associated theoretical development, is described.

  12. Cold knife cone biopsy

    Science.gov (United States)

    ... biopsy; Pap smear - cone biopsy; HPV - cone biopsy; Human papilloma virus - cone biopsy; Cervix - cone biopsy; Colposcopy - cone biopsy Images Female reproductive anatomy Cold cone biopsy Cold cone removal References American ...

  13. A comparative study between cone-beam computed tomography and periapical radiographs in the diagnosis of simulated endodontic complications.

    Science.gov (United States)

    D'Addazio, P S S; Campos, C N; Özcan, M; Teixeira, H G C; Passoni, R M; Carvalho, A C P

    2011-03-01

    To compare cone-beam computed tomography (CBCT) with periapical radiography for the identification of simulated endodontic complications. Sixteen human teeth, in three mandibles, were submitted to the following simulated endodontic complications: G1) fractured endodontic file; G2) root perforation; G3) cast post with deviation; G4) external root resorption. Periapical radiographs were taken of each tooth at three different angles, and CBCT scan was taken. One calibrated examiner who was specialized in dental radiology interpreted the images. The results were analysed using the following scoring system: 0 - unidentified alteration; 1 - alteration identified with inaccurate diagnosis; and 2 - alteration identified with accurate diagnosis. Data were analysed using McNemar and Wilcoxon tests (alfa=0.05). In the overall assessment, CBCT was superior when compared with periapical radiographs (Pperiapical radiographs especially in the detection and assessment of external root resorption. © 2010 International Endodontic Journal.

  14. Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations.

    Science.gov (United States)

    Kim, Sangroh; Yoshizumi, Terry T; Toncheva, Greta; Frush, Donald P; Yin, Fang-Fang

    2010-03-01

    The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry.

  15. SU-D-12A-01: An Inter-Projection Interpolation (IPI) Approach for the Synchronized Moving Grid (SMOG) to Reduce Dose in Cone Beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H; Kong, V; Jin, J [Georgia Regents University, Augusta, GA (Georgia); Ren, L [Duke University Medical Center, Durham, NC (United States)

    2014-06-01

    Purpose: Synchronized moving grid is a promising technique to reduce scatter and ghost artifacts in cone beam computed tomography (CBCT). However, it requires 2 projections in the same gantry angle to obtain full information due to signal blockage by the grid. We proposed an inter-projection interpolation (IPI) method to estimate blocked signals, which may reduce the scan time and the dose. This study aims to provide a framework to achieve a balance between speed, dose and image quality. Methods: The IPI method is based on the hypothesis that an abrupt signal in a projection can be well predicted by the information in the two immediate neighboring projections if the gantry angle step is small. The study was performed on a Catphan and a head phantom. The SMOG was simulated by erasing the information (filling with “0”) of the areas in each projection corresponding to the grid. An IPI algorithm was applied on each projection to recover the erased information. FDK algorithm was used to reconstruct CBCT images for the IPI-processed projections, and compared with the original image in term of signal to noise ratio (SNR) measured in the whole reconstruction image range. The effect of gantry angle step was investigated by comparing the CBCT images from projection sets of various gantry intervals, with IPI-predicted projections to fill the missing projection in the interval. Results: The IPI procession time was 1.79s±0.53s for each projection. SNR after IPI was 29.0db and 28.1db for the Catphan and head phantom, respectively, comparing to 15.3db and 22.7db for an inpainting based interpolation technique. SNR was 28.3, 28.3, 21.8, 19.3 and 17.3 db for gantry angle intervals of 1, 1.5, 2, 2.5 and 3 degrees, respectively. Conclusion: IPI is feasible to estimate the missing information, and achieve an reasonable CBCT image quality with reduced dose and scan time. This study is supported by NIH/NCI grant 1R01CA166948-01.

  16. S-cone psychophysics.

    Science.gov (United States)

    Smithson, Hannah E

    2014-03-01

    We review the features of the S-cone system that appeal to the psychophysicist and summarize the celebrated characteristics of S-cone mediated vision. Two factors are emphasized: First, the fine stimulus control that is required to isolate putative visual mechanisms and second, the relationship between physiological data and psychophysical approaches. We review convergent findings from physiology and psychophysics with respect to asymmetries in the retinal wiring of S-ON and S-OFF visual pathways, and the associated treatment of increments and decrements in the S-cone system. Beyond the retina, we consider the lack of S-cone projections to superior colliculus and the use of S-cone stimuli in experimental psychology, for example to address questions about the mechanisms of visually driven attention. Careful selection of stimulus parameters enables psychophysicists to produce entirely reversible, temporary, "lesions," and to assess behavior in the absence of specific neural subsystems.

  17. Phasor Simulator for Operator Training Project

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, Jim [Electric Power Group, Llc, Pasadena, CA (United States)

    2016-09-14

    Synchrophasor systems are being deployed in power systems throughout the North American Power Grid and there are plans to integrate this technology and its associated tools into Independent System Operator (ISO)/utility control room operations. A pre-requisite to using synchrophasor technologies in control rooms is for operators to obtain training and understand how to use this technology in real-time situations. The Phasor Simulator for Operator Training (PSOT) project objective was to develop, deploy and demonstrate a pre-commercial training simulator for operators on the use of this technology and to promote acceptance of the technology in utility and ISO/Regional Transmission Owner (RTO) control centers.

  18. Agent-Based Simulations for Project Management

    Science.gov (United States)

    White, J. Chris; Sholtes, Robert M.

    2011-01-01

    Currently, the most common approach used in project planning tools is the Critical Path Method (CPM). While this method was a great improvement over the basic Gantt chart technique being used at the time, it now suffers from three primary flaws: (1) task duration is an input, (2) productivity impacts are not considered , and (3) management corrective actions are not included. Today, computers have exceptional computational power to handle complex simulations of task e)(eculion and project management activities (e.g ., dynamically changing the number of resources assigned to a task when it is behind schedule). Through research under a Department of Defense contract, the author and the ViaSim team have developed a project simulation tool that enables more realistic cost and schedule estimates by using a resource-based model that literally turns the current duration-based CPM approach "on its head." The approach represents a fundamental paradigm shift in estimating projects, managing schedules, and reducing risk through innovative predictive techniques.

  19. GPU-based Fast Cone Beam CT Reconstruction from Undersampled and Noisy Projection Data via Total Variation

    CERN Document Server

    Jia, Xun; Li, Ruijiang; Song, William Y; Jiang, Steve B

    2010-01-01

    Cone-beam CT (CBCT) plays an important role in image guided radiation therapy (IGRT). However, the large radiation dose from serial CBCT scans in most IGRT procedures raises a clinical concern, especially for pediatric patients who are essentially excluded from receiving IGRT for this reason. To lower the imaging dose, we have developed a fast GPU-based CBCT reconstruction algorithm. The CBCT is reconstructed by minimizing an energy functional consisting of a data fidelity term and a total variation regularization term. We developed a GPU-friendly version of the forward-backward splitting algorithm to solve this model. Multi-grid technique is also employed. It is found that 20~40 x-ray projections are sufficient to reconstruct images with satisfactory quality for IGRT. The reconstruction time ranges from 77 to 130 sec on a NVIDIA Tesla C1060 GPU card, depending on the number of projections used, which is estimated about 100 times faster than similar iterative reconstruction approaches. Moreover, phantom studi...

  20. Effects of Cone-Shaped Bend Inlet Cannulas of an Axial Blood Pump on Thrombus Formation: An Experiment and Simulation Study.

    Science.gov (United States)

    Liu, Guangmao; Zhou, Jianye; Sun, Hansong; Zhang, Yan; Chen, Haibo; Hu, Shengshou

    2017-04-05

    BACKGROUND Cannula shape and connection style influence the risk of thrombus formation in the blood pump by varying the blood flow characteristics inside the pump. Inlet cannulas should be designed based on the need for anatomical fit and reducing the risk of thrombus generation in the blood pump. The effects on thrombus formation of the cone-shaped bend inlet cannulas of axial blood pumps should be studied. MATERIAL AND METHODS The cannulas were designed as cone-shaped, with 1 bent section connecting 2 straight sections. Both the silicone tube and novel cone-shaped cannula were simulated for comparison. The flow fields of a blood pump with inlet cannula were simulated by computational fluid dynamics (CFD) at flows of 2.0, 2.5, and 3.0 liters per minute (lpm), with pump rotational speeds of 7500, 8000, and 8500 rpm, respectively. Then, 6 two-dimensional (2D) particle image velocimetry (PIV) tests were conducted and the velocity distributions were analyzed. RESULTS A low-velocity region was located inside the pump entrance when a soft silicone tube was used. At 8500 rpm and 3.0 lpm working condition, the minimum velocity inside the pump with cone-shaped cannulas was 2.5×10^-1 m/s. The cone-shaped cannulas eliminated the low-velocity region inside the pump. Both CFD and PIV results showed that the low-velocity region did not spread to the entrance of the blood pump within the flow range from 2.0 lpm to 7.0 lpm. CONCLUSIONS The designed cone-shaped bent cannulas can eliminate the low-velocity region inside the blood pump and reduce the risk of thrombus formation in the blood pump.

  1. Simulating Halos with the Caterpillar Project

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    The Caterpillar Project is a beautiful series of high-resolution cosmological simulations. The goal of this project is to examine the evolution of dark-matter halos like the Milky Ways, to learn about how galaxies like ours formed. This immense computational project is still in progress, but the Caterpillar team is already providing a look at some of its first results.Lessons from Dark-Matter HalosWhy simulate the dark-matter halos of galaxies? Observationally, the formation history of our galaxy is encoded in galactic fossil record clues, like the tidal debris from disrupted satellite galaxies in the outer reaches of our galaxy, or chemical abundance patterns throughout our galactic disk and stellar halo.But to interpret this information in a way that lets us learn about our galaxys history, we need to first test galaxy formation and evolution scenarios via cosmological simulations. Then we can compare the end result of these simulations to what we observe today.This figure illustrates the difference that mass resolution makes. In the left panel, the mass resolution is 1.5*10^7 solar masses per particle. In the right panel, the mass resolution is 3*10^4 solar masses per particle [Griffen et al. 2016]A Computational ChallengeDue to how computationally expensive such simulations are, previous N-body simulations of the growth of Milky-Way-like halos have consisted of only one or a few halos each. But in order to establish a statistical understanding of how galaxy halos form and find out whether the Milky Ways halo is typical or unusual! it is necessary to simulate a larger number of halos.In addition, in order to accurately follow the formation and evolution of substructure within the dark-matter halos, these simulations must be able to resolve the smallest dwarf galaxies, which are around a million solar masses. This requires an extremely high mass resolution, which adds to the computational expense of the simulation.First OutcomesThese are the challenges faced by

  2. Estimation of computed tomography dose index in cone beam computed tomography: MOSFET measurements and Monte Carlo simulations.

    Science.gov (United States)

    Kim, Sangroh; Yoshizumi, Terry; Toncheva, Greta; Yoo, Sua; Yin, Fang-Fang; Frush, Donald

    2010-05-01

    To address the lack of accurate dose estimation method in cone beam computed tomography (CBCT), we performed point dose metal oxide semiconductor field-effect transistor (MOSFET) measurements and Monte Carlo (MC) simulations. A Varian On-Board Imager (OBI) was employed to measure point doses in the polymethyl methacrylate (PMMA) CT phantoms with MOSFETs for standard and low dose modes. A MC model of the OBI x-ray tube was developed using BEAMnrc/EGSnrc MC system and validated by the half value layer, x-ray spectrum and lateral and depth dose profiles. We compared the weighted computed tomography dose index (CTDIw) between MOSFET measurements and MC simulations. The CTDIw was found to be 8.39 cGy for the head scan and 4.58 cGy for the body scan from the MOSFET measurements in standard dose mode, and 1.89 cGy for the head and 1.11 cGy for the body in low dose mode, respectively. The CTDIw from MC compared well to the MOSFET measurements within 5% differences. In conclusion, a MC model for Varian CBCT has been established and this approach may be easily extended from the CBCT geometry to multi-detector CT geometry.

  3. Automated patient setup and gating using cone beam computed tomography projections

    DEFF Research Database (Denmark)

    Wan, Hanlin; Bertholet, Jenny; Ge, Jiajia

    2016-01-01

    in the planning CT. This step is time-intensive and user-dependent, and often results in a suboptimal patient setup. We propose a fully automated, robust method based on dynamic programming (DP) for segmenting radiopaque fiducial markers in CBCT projection images, which are then used to automatically optimize...... the treatment couch position and/or gating window bounds. The mean of the absolute 2D segmentation error of our DP algorithm is [Formula: see text] mm for 87 markers on 39 patients. Intrafraction images were acquired every 3 s during treatment at two different institutions. For gated patients from Institution...

  4. Fully automatic segmentation of arbitrarily shaped fiducial markers in cone-beam CT projections

    DEFF Research Database (Denmark)

    Bertholet, Jenny; Wan, Hanlin; Toftegaard, Jakob

    2017-01-01

    segmentation, the DPTB algorithm generates and uses a 3D marker model to create 2D templates at any projection angle. The 2D templates are used to segment the marker position as the position with highest normalized cross-correlation in a search area centered at the DP segmented position. The accuracy of the DP...... algorithm and the new DPTB algorithm was quantified as the 2D segmentation error (pixels) compared to a manual ground truth segmentation for 97 markers in the projection images of CBCT scans of 40 patients. Also the fraction of wrong segmentations, defined as 2D errors larger than 5 pixels, was calculated....... The mean 2D segmentation error of DP was reduced from 4.1 pixels to 3.0 pixels by DPTB, while the fraction of wrong segmentations was reduced from 17.4% to 6.8%. DPTB allowed rejection of uncertain segmentations as deemed by a low normalized cross-correlation coefficient and contrast-to-noise ratio...

  5. Cone Algorithm of Spinning Vehicles under Dynamic Coning Environment

    Directory of Open Access Journals (Sweden)

    Shuang-biao Zhang

    2015-01-01

    Full Text Available Due to the fact that attitude error of vehicles has an intense trend of divergence when vehicles undergo worsening coning environment, in this paper, the model of dynamic coning environment is derived firstly. Then, through investigation of the effect on Euler attitude algorithm for the equivalency of traditional attitude algorithm, it is found that attitude error is actually the roll angle error including drifting error and oscillating error, which is induced directly by dynamic coning environment and further affects the pitch angle and yaw angle through transferring. Based on definition of the cone frame and cone attitude, a cone algorithm is proposed by rotation relationship to calculate cone attitude, and the relationship between cone attitude and Euler attitude of spinning vehicle is established. Through numerical simulations with different conditions of dynamic coning environment, it is shown that the induced error of Euler attitude fluctuates by the variation of precession and nutation, especially by that of nutation, and the oscillating frequency of roll angle error is twice that of pitch angle error and yaw angle error. In addition, the rotation angle is more competent to describe the spinning process of vehicles under coning environment than Euler angle gamma, and the real pitch angle and yaw angle are calculated finally.

  6. Low-contrast visualization in megavoltage cone-beam CT at one beam pulse per projection using thick segmented scintillators

    Science.gov (United States)

    El-Mohri, Youcef; Antonuk, Larry E.; Zhao, Qihua; Choroszucha, Richard B.; Wang, Yi

    2010-04-01

    Megavoltage cone-beam computed tomography (MV CBCT) using an electronic portal imaging device (EPID) is a highly promising technique for providing valuable volumetric information for image guidance in radiotherapy. However, active matrix flat-panel imagers (AMFPIs), which are the established gold standard in portal imaging, require a relatively large dose to create images that are clinically useful. This is a consequence of the inefficiency of the phosphor screens employed in conventional MV AMFPIs, which utilize only ~2% of the incident radiation at 6 MV. Fortunately, the incorporation of thick, segmented scintillators can significantly improve the performance of MV AMFPIs, leading to improved image quality for projection imaging at extremely low dose. It is therefore of interest to explore the performance of such thick scintillators for MV CBCT toward the goal of soft-tissue contrast visualization. In this study, prototype AMFPIs incorporating segmented scintillators based on CsI:Tl and BGO crystals with thicknesses ranging from ~11 to 25 mm have been constructed and evaluated. Each prototype incorporates a detector consisting of a matrix of 120 × 60 scintillator elements separated by reflective septal walls, with an element-to-element pitch of 1.016 mm, coupled to an overlying ~1 mm thick Cu plate. The prototype AMFPIs were incorporated into a bench-top CBCT system, allowing the acquisition of tomographic images of a contrast phantom using a 6 MV radiotherapy photon beam. The phantom consists of a water-equivalent (solid water) cylinder, embedded with tissue-equivalent inserts having electron densities, relative to water, varying from ~0.43 to ~1.47. Reconstructed images of the phantom were obtained down to the lowest available dose (one beam pulse per projection), corresponding to a total scan dose of ~4 cGy using 180 projections. In this article, reconstructed images, contrast, noise and contrast-to-noise ratio for the tissue-equivalent objects using the

  7. Analysis of New Aerodynamic Design of the Nose Cone Section Using CFD and SPH

    Directory of Open Access Journals (Sweden)

    Bogdan-Alexandru BELEGA

    2015-06-01

    Full Text Available A new nose cones concept that promises a gain in performance over existing conventional nose cones is discussed in this paper. It is shown that significant performance gains result from the adaptation of the exhaust flow to the ambient pressure. For this complex work, it was necessary to collect and study the various nose cone shapes and the equations describing them? The paper objective was to identify the types of nose cones with ejector channels and specific aerodynamic characteristics of different types of nose cones. The scope of this paper is to develop some prototype profiles with outstanding aerodynamic qualities and low cost for use in construction projects for missile increasing their range and effect on target. The motivation for such a work is caused by a lack of data on aerodynamics for profiles of some nose cones and especially improved aerodynamic qualities that can be used in designing missiles/ rockets. This design method consists of a geometry creation step in which a three-dimensional geometry is generated, a mathematical model presented and a simple flow analysis (FLUENT Simulation from SolidWorks2012 and ANSYS Simulation with SPH for fluid-structure interaction, step which predicts the air intake mass flow rate. Flow phenomena observed in numerical simulations during different nose cone operations are highlighted, critical design aspects and operation conditions are discussed, and performance characteristics of the selected nose cone are presented.

  8. The use of cone-beam computed tomography and virtual reality simulation for pre-surgical practice in endodontic microsurgery.

    Science.gov (United States)

    Suebnukarn, S; Rhienmora, P; Haddawy, P

    2012-07-01

    To design and evaluate the impact of virtual reality (VR) pre-surgical practice on the performance of actual endodontic microsurgery.   The VR system operates on a laptop with a 1.6-GHz Intel processor and 2 GB of main memory. Volumetric cone-beam computed tomography (CBCT) data were acquired from a fresh cadaveric porcine mandible prior to endodontic microsurgery. Ten inexperienced endodontic trainees were randomized as to whether they performed endodontic microsurgery with or without virtual pre-surgical practice. The VR simulator has microinstruments to perform surgical procedures under magnification. After the initial endodontic microsurgery, all participants served as their own controls by performing another procedure with or without virtual pre-surgical practice. All procedures were videotaped and assessed by two independent observers using an endodontic competency rating scale (from 6 to 30). A significant difference was observed between the scores for endodontic microsurgery on molar teeth completed with virtual pre-surgical practice and those completed without virtual presurgical practice, median 24.5 (range = 17-28) versus median 18.75 (range = 14-26.5), P = 0.041. A significant difference was observed between the scores for osteotomy on a molar tooth completed with virtual pre-surgical practice and those completed without virtual pre-surgical practice, median 4.5 (range = 3.5-4.5) versus median 3 (range = 2-4), P = 0.042. Pre-surgical practice in a virtual environment using the 3D computerized model generated from the original CBCT image data improved endodontic microsurgery performance. © 2012 International Endodontic Journal.

  9. Light cone matrix product

    Energy Technology Data Exchange (ETDEWEB)

    Hastings, Matthew B [Los Alamos National Laboratory

    2009-01-01

    We show how to combine the light-cone and matrix product algorithms to simulate quantum systems far from equilibrium for long times. For the case of the XXZ spin chain at {Delta} = 0.5, we simulate to a time of {approx} 22.5. While part of the long simulation time is due to the use of the light-cone method, we also describe a modification of the infinite time-evolving bond decimation algorithm with improved numerical stability, and we describe how to incorporate symmetry into this algorithm. While statistical sampling error means that we are not yet able to make a definite statement, the behavior of the simulation at long times indicates the appearance of either 'revivals' in the order parameter as predicted by Hastings and Levitov (e-print arXiv:0806.4283) or of a distinct shoulder in the decay of the order parameter.

  10. different outer cone angle

    Directory of Open Access Journals (Sweden)

    Smyk Emil

    2017-01-01

    Full Text Available One of the method of flow separation control is application of axisymmetric valve. It is composed of nozzle with core. Normally the main flow is attached to inner cone and flow by preferential collector to primary flow pipe. If through control nozzle starts flow jet (control jet the main flow is switched to annular secondary collector. In both situation the main flow is deflected to inner or outer cone (placed at the outlet of the valve’s nozzle by Coanda effect. The paper deals with the numerical simulation of this axisymetric annular nozzle with integrated synthetic jet actuator. The aim of the work is influence examination of outer cone angle on deflection on main stream.

  11. Binary moving-blocker-based scatter correction in cone-beam computed tomography with width-truncated projections: proof of concept

    Science.gov (United States)

    Lee, Ho; Fahimian, Benjamin P.; Xing, Lei

    2017-03-01

    This paper proposes a binary moving-blocker (BMB)-based technique for scatter correction in cone-beam computed tomography (CBCT). In concept, a beam blocker consisting of lead strips, mounted in front of the x-ray tube, moves rapidly in and out of the beam during a single gantry rotation. The projections are acquired in alternating phases of blocked and unblocked cone beams, where the blocked phase results in a stripe pattern in the width direction. To derive the scatter map from the blocked projections, 1D B-Spline interpolation/extrapolation is applied by using the detected information in the shaded regions. The scatter map of the unblocked projections is corrected by averaging two scatter maps that correspond to their adjacent blocked projections. The scatter-corrected projections are obtained by subtracting the corresponding scatter maps from the projection data and are utilized to generate the CBCT image by a compressed-sensing (CS)-based iterative reconstruction algorithm. Catphan504 and pelvis phantoms were used to evaluate the method’s performance. The proposed BMB-based technique provided an effective method to enhance the image quality by suppressing scatter-induced artifacts, such as ring artifacts around the bowtie area. Compared to CBCT without a blocker, the spatial nonuniformity was reduced from 9.1% to 3.1%. The root-mean-square error of the CT numbers in the regions of interest (ROIs) was reduced from 30.2 HU to 3.8 HU. In addition to high resolution, comparable to that of the benchmark image, the CS-based reconstruction also led to a better contrast-to-noise ratio in seven ROIs. The proposed technique enables complete scatter-corrected CBCT imaging with width-truncated projections and allows reducing the acquisition time to approximately half. This work may have significant implications for image-guided or adaptive radiation therapy, where CBCT is often used.

  12. Improving Project Management with Simulation and Completion Distribution Functions

    Science.gov (United States)

    Cates, Grant R.

    2004-01-01

    Despite the critical importance of project completion timeliness, management practices in place today remain inadequate for addressing the persistent problem of project completion tardiness. A major culprit in late projects is uncertainty, which most, if not all, projects are inherently subject to. This uncertainty resides in the estimates for activity durations, the occurrence of unplanned and unforeseen events, and the availability of critical resources. In response to this problem, this research developed a comprehensive simulation based methodology for conducting quantitative project completion time risk analysis. It is called the Project Assessment by Simulation Technique (PAST). This new tool enables project stakeholders to visualize uncertainty or risk, i.e. the likelihood of their project completing late and the magnitude of the lateness, by providing them with a completion time distribution function of their projects. Discrete event simulation is used within PAST to determine the completion distribution function for the project of interest. The simulation is populated with both deterministic and stochastic elements. The deterministic inputs include planned project activities, precedence requirements, and resource requirements. The stochastic inputs include activity duration growth distributions, probabilities for events that can impact the project, and other dynamic constraints that may be placed upon project activities and milestones. These stochastic inputs are based upon past data from similar projects. The time for an entity to complete the simulation network, subject to both the deterministic and stochastic factors, represents the time to complete the project. Repeating the simulation hundreds or thousands of times allows one to create the project completion distribution function. The Project Assessment by Simulation Technique was demonstrated to be effective for the on-going NASA project to assemble the International Space Station. Approximately $500

  13. Cone Penetration Test and Soil Boring at the Bayside Groundwater Project Site in San Lorenzo, Alameda County, California

    Science.gov (United States)

    Bennett, Michael J.; Sneed, Michelle; Noce, Thomas E.; Tinsley, John C.

    2009-01-01

    Aquifer-system deformation associated with ground-water-level changes is being investigated cooperatively by the U.S. Geological Survey (USGS) and the East Bay Municipal Utility District (EBMUD) at the Bayside Groundwater Project (BGP) near the modern San Francisco Bay shore in San Lorenzo, California. As a part of this project, EBMUD has proposed an aquifer storage and recovery (ASR) program to store and recover as much as 3.78x104 m3/d of water. Water will be stored in a 30-m sequence of coarse-grained sediment (the 'Deep Aquifer') underlying the east bay alluvium and the adjacent ground-water basin. Storing and recovering water could cause subsidence and uplift at the ASR site and adjacent areas because the land surface will deform as aquifers and confining units elastically expand and contract with ASR cycles. The Deep Aquifer is overlain by more than 150 m of clayey fine-grained sediments and underlain by comparable units. These sediments are similar to the clayey sediments found in the nearby Santa Clara Valley, where inelastic compaction resulted in about 4.3 m of subsidence near San Jose from 1910 to 1995 due to overdraft of the aquifer. The Deep Aquifer is an important regional resource, and EBMUD is required to demonstrate that ASR activities will not affect nearby ground-water management, salinity levels, or cause permanent land subsidence. Subsidence in the east bay area could induce coastal flooding and create difficulty conveying winter storm runoff from urbanized areas. The objective of the cooperative investigation is to monitor and analyze aquifer-system compaction and expansion, as well as consequent land subsidence and uplift resulting from natural causes and any anthropogenic causes related to ground-water development and ASR activities at the BGP. Therefore, soil properties related to compressibility (and the potential for deformation associated with ground-water-level changes) are of the most concern. To achieve this objective, 3 boreholes

  14. FATRAS - the ATLAS Fast Track Simulation project

    NARCIS (Netherlands)

    Mechnich, J.

    2011-01-01

    The Monte Carlo simulation of the detector response is an integral component of any analysis performed with data from the LHC experiments. As these simulated data sets must be both large and precise, their production is a CPU-intensive task. ATLAS has developed full and fast detector simulation

  15. Dynamic Damage Modeling for IRAC Simulations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's Integrated Resilient Aircraft Control (IRAC) Project, Preliminary Technical Plan Summary identifies several causal and contributing factors that can lead to...

  16. Production of Synthetic Lunar Simulants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Zybek Advanced Products has proven the ability to produce industrial quantities of lunar simulant materials, including glass, agglutinate and melt breccias. These...

  17. Monte Carlo simulation of the dose distribution of ICRP adult reference computational phantoms for acquisitions with a 320 detector-row cone-beam CT scanner.

    Science.gov (United States)

    Salvadó, M; Cros, M; Joemai, R M S; Calzado, A; Geleijns, J

    2015-07-01

    The purpose of this study was to develop and validate a Monte Carlo (MC) simulation tool for patient dose assessment for a 320 detector-row CT scanner, based on the recommendations of International Commission on Radiological Protection (ICRP). Additionally, the simulation was applied on four clinical acquisition protocols, with and without automatic tube current modulation (TCM). The MC simulation was based on EGS4 code and was developed specifically for a 320 detector-row cone-beam CT scanner. The ICRP adult reference phantoms were used as patient models. Dose measurements were performed free-in-air and also in four CTDI phantoms: 150 mm and 350 mm long CT head and CT body phantoms. The MC program was validated by comparing simulations results with these actual measurements acquired under the same conditions. The measurements agreed with the simulations across all conditions within 5%. Patient dose assessment was performed for four clinical axial acquisitions using the ICRP adult reference phantoms, one of them using TCM. The results were nearly always lower than those obtained from other dose calculator tools or published in other studies, which were obtained using mathematical phantoms in different CT systems. For the protocol with TCM organ doses were reduced by between 28 and 36%, compared to the results obtained using a fixed mA value. The developed simulation program provides a useful tool for assessing doses in a 320 detector-row cone-beam CT scanner using ICRP adult reference computational phantoms and is ready to be applied to more complex protocols. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  18. SimDoseCT: dose reporting software based on Monte Carlo simulation for a 320 detector-row cone-beam CT scanner and ICRP computational adult phantoms

    Science.gov (United States)

    Cros, Maria; Joemai, Raoul M. S.; Geleijns, Jacob; Molina, Diego; Salvadó, Marçal

    2017-08-01

    This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT

  19. A Simulation Integrated Investment Project Ranking and Selection Approach

    Directory of Open Access Journals (Sweden)

    Ozgur YALCINKAYA

    2012-07-01

    Full Text Available Enterprises are confronted with several project alternatives that they assume to gain revenue in the future, but their own economical resources are limited to carry out all alternatives. Therefore, a decision process arises to prioritize and select among alternatives according to the predetermined goals and criteria to reach the maximum utilization. On the other hand, in project evaluation, the values of project parameters are often assumed to be known with complete certainty. However, project parameters normally change during a life cycle of the project, and it is necessary to consider uncertainty and risk phenomena while evaluating projects. Simulation-based project evaluation approaches enable to make more reliable investment decision since they permit to include future uncertainty and risk in analysis process. In this article, a novel simulation-based optimal decision approach is proposed for evaluating and comparing investment projects under uncertain and/or risky environments. The phases of the proposed approach are; (a developing the effectiveness measure formulation of a project, (b identifying and checking all controllable project parameters that affect the measure, (c developing simulation model for the measure, and (d performing the project ranking and selection procedures in order to rank and select the projects. Three ranking and selection procedures, previously used for comparing performances of the different production/service systems, are embedded in the proposed approach.

  20. Visual Interfaces for Parallel Simulations (VIPS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Configuring the 3D geometry and physics of large scale parallel physics simulations is increasingly complex. Given the investment in time and effort to run these...

  1. Uncertainty Quantification in Aerodynamics Simulations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the proposed work (Phases I and II) is to develop uncertainty quantification methodologies and software suitable for use in CFD simulations of...

  2. Improved Lunar and Martian Regolith Simulant Production Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objective of the Phase II project is to provide a more complete investigation of the long-term needs of the simulant community based on the updated...

  3. Geomorphometric variability of "monogenetic" volcanic cones: Evidence from Mauna Kea, Lanzarote and experimental cones

    Science.gov (United States)

    Kervyn, M.; Ernst, G. G. J.; Carracedo, J.-C.; Jacobs, P.

    2012-01-01

    Volcanic cones are the most common volcanic constructs on Earth. Their shape can be quantified using two morphometric ratios: the crater/cone base ratio (W cr/W co) and the cone height/width ratio (H co/W co). The average values for these ratios obtained over entire cone fields have been explained by the repose angle of loose granular material (i.e. scoria) controlling cone slopes. The observed variability in these ratios between individual cones has been attributed to the effect of erosional processes or contrasting eruptive conditions on cone morphometry. Using a GIS-based approach, high spatial resolution Digital Elevation Models and airphotos, two new geomorphometry datasets for cone fields at Mauna Kea (Hawaii, USA) and Lanzarote (Canary Islands, Spain) are extracted and analyzed here. The key observation in these datasets is the great variability in morphometric ratios, even for simple-shape and well-preserved cones. Simple analog experiments are presented to analyze factors influencing the morphometric ratios. The formation of a crater is simulated within an analog cone (i.e. a sand pile) by opening a drainage conduit at the cone base. Results from experiments show that variability in the morphometric ratios can be attributed to variations in the width, height and horizontal offset of the drainage point relative to the cone symmetry axis, to the dip of the underlying slope or to the influence of a small proportion of fine cohesive material. GIS analysis and analog experiments, together with specific examples of cones documented in the field, suggest that the morphometric ratios for well-preserved volcanic cones are controlled by a combination of 1) the intrinsic cone material properties, 2) time-dependent eruption conditions, 3) the local setting, and 4) the method used to estimate the cone height. Implications for interpreting cone morphometry solely as either an age or as an eruption condition indicator are highlighted.

  4. A Project Management Approach to Using Simulation for Cost Estimation on Large, Complex Software Development Projects

    Science.gov (United States)

    Mizell, Carolyn; Malone, Linda

    2007-01-01

    It is very difficult for project managers to develop accurate cost and schedule estimates for large, complex software development projects. None of the approaches or tools available today can estimate the true cost of software with any high degree of accuracy early in a project. This paper provides an approach that utilizes a software development process simulation model that considers and conveys the level of uncertainty that exists when developing an initial estimate. A NASA project will be analyzed using simulation and data from the Software Engineering Laboratory to show the benefits of such an approach.

  5. Simulating Positive-Operator-Valued Measures with Projective Measurements

    Science.gov (United States)

    Oszmaniec, Michał; Guerini, Leonardo; Wittek, Peter; Acín, Antonio

    2017-11-01

    Standard projective measurements (PMs) represent a subset of all possible measurements in quantum physics, defined by positive-operator-valued measures. We study what quantum measurements are projective simulable, that is, can be simulated by using projective measurements and classical randomness. We first prove that every measurement on a given quantum system can be realized by classical randomization of projective measurements on the system plus an ancilla of the same dimension. Then, given a general measurement in dimension two or three, we show that deciding whether it is PM simulable can be solved by means of semidefinite programming. We also establish conditions for the simulation of measurements using projective ones valid for any dimension. As an application of our formalism, we improve the range of visibilities for which two-qubit Werner states do not violate any Bell inequality for all measurements. From an implementation point of view, our work provides bounds on the amount of white noise a measurement tolerates before losing any advantage over projective ones.

  6. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    Energy Technology Data Exchange (ETDEWEB)

    Shieh, Chun-Chien [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006, Australia and Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia); Kipritidis, John; O’Brien, Ricky T.; Keall, Paul J., E-mail: paul.keall@sydney.edu.au [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006 (Australia); Kuncic, Zdenka [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia)

    2014-04-15

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR

  7. Proposed best practice for projects that involve modelling and simulation.

    Science.gov (United States)

    O'Kelly, Michael; Anisimov, Vladimir; Campbell, Chris; Hamilton, Sinéad

    2017-03-01

    Modelling and simulation has been used in many ways when developing new treatments. To be useful and credible, it is generally agreed that modelling and simulation should be undertaken according to some kind of best practice. A number of authors have suggested elements required for best practice in modelling and simulation. Elements that have been suggested include the pre-specification of goals, assumptions, methods, and outputs. However, a project that involves modelling and simulation could be simple or complex and could be of relatively low or high importance to the project. It has been argued that the level of detail and the strictness of pre-specification should be allowed to vary, depending on the complexity and importance of the project. This best practice document does not prescribe how to develop a statistical model. Rather, it describes the elements required for the specification of a project and requires that the practitioner justify in the specification the omission of any of the elements and, in addition, justify the level of detail provided about each element. This document is an initiative of the Special Interest Group for modelling and simulation. The Special Interest Group for modelling and simulation is a body open to members of Statisticians in the Pharmaceutical Industry and the European Federation of Statisticians in the Pharmaceutical Industry. Examples of a very detailed specification and a less detailed specification are included as appendices. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Light-cone quantization of quantum chromodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Pauli, H.C. (Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany, F.R.))

    1991-06-01

    We discuss the light-cone quantization of gauge theories from two perspectives: as a calculational tool for representing hadrons as QCD bound-states of relativistic quarks and gluons, and also as a novel method for simulating quantum field theory on a computer. The light-cone Fock state expansion of wavefunctions at fixed light cone time provides a precise definition of the parton model and a general calculus for hadronic matrix elements. We present several new applications of light-cone Fock methods, including calculations of exclusive weak decays of heavy hadrons, and intrinsic heavy-quark contributions to structure functions. A general nonperturbative method for numerically solving quantum field theories, discretized light-cone quantization,'' is outlined and applied to several gauge theories, including QCD in one space and one time dimension, and quantum electrodynamics in physical space-time at large coupling strength. The DLCQ method is invariant under the large class of light-cone Lorentz transformations, and it can be formulated such at ultraviolet regularization is independent of the momentum space discretization. Both the bound-state spectrum and the corresponding relativistic light-cone wavefunctions can be obtained by matrix diagonalization and related techniques. We also discuss the construction of the light-cone Fock basis, the structure of the light-cone vacuum, and outline the renormalization techniques required for solving gauge theories within the light-cone Hamiltonian formalism.

  9. Cone Penetrometer N Factor Determination Testing Results

    Energy Technology Data Exchange (ETDEWEB)

    Follett, Jordan R.

    2014-03-05

    This document contains the results of testing activities to determine the empirical 'N Factor' for the cone penetrometer in kaolin clay simulant. The N Factor is used to releate resistance measurements taken with the cone penetrometer to shear strength.

  10. Process simulation and parametric modeling for strategic project management

    CERN Document Server

    Morales, Peter J

    2013-01-01

    Process Simulation and Parametric Modeling for Strategic Project Management will offer CIOs, CTOs and Software Development Managers, IT Graduate Students an introduction to a set of technologies that will help them understand how to better plan software development projects, manage risk and have better insight into the complexities of the software development process.A novel methodology will be introduced that allows a software development manager to better plan and access risks in the early planning of a project.  By providing a better model for early software development estimation and softw

  11. M3D project for simulation studies of plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Park, W.; Belova, E.V.; Fu, G.Y. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Strauss, H.R. [New York Univ., NY (United States); Sugiyama, L.E. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1998-12-31

    The M3D (Multi-level 3D) project carries out simulation studies of plasmas of various regimes using multi-levels of physics, geometry, and mesh schemes in one code package. This paper and papers by Strauss, Sugiyama, and Belova in this workshop describe the project, and present examples of current applications. The currently available physics models of the M3D project are MHD, two-fluids, gyrokinetic hot particle/MHD hybrid, and gyrokinetic particle ion/two-fluid hybrid models. The code can be run with both structured and unstructured meshes.

  12. Comparative study of cone beam computed tomography and intraoral periapical radiographs in diagnosis of lingual-simulated external root resorptions.

    Science.gov (United States)

    Bernardes, Ricardo Affonso; de Paulo, Renata Silvéria; Pereira, Luciana Oliveira; Duarte, Marco Antonio Hungaro; Ordinola-Zapata, Ronald; de Azevedo, José Ribamar

    2012-08-01

    Owing to a lack of symptoms and difficult visualization in routine intraoral radiographs, diagnosis of external root resorptions can be challenging. The goal of this study was to compare two image acquisition methods, intraoral radiographs and cone beam computed tomography (CBCT), in the diagnosis of external resorption. Thirty-four maxillary and mandibular bicuspids were divided into three groups. Perforations measuring 0.3 and 0.6 mm in diameter and 0.15 and 0.3 mm in depth, respectively, were made on the lingual root surfaces in thirty teeth, and four were used as controls. Next, teeth were mounted on an apparatus and radiographed at mesial, distal, and orthoradial angulations. CBCT images were also taken. The analysis of the intraoral radiographic and tomographic images was carried out by two experts using standardized scores. Data were then compared statistically. A strong agreement between the examiners was observed in both diagnosis methods, the intraoral radiographic (r = 0.93) and the tomographic analysis (r = 1.0). Tomography had higher statistically significant detection values than intraoral radiography (P intraoral radiographs, the detection was significantly greater (P intraoral radiography was significantly higher than that of 0.3-mm perforations (P intraoral radiography, regardless of the tooth or the dimensions of the resorption evaluated. © 2012 John Wiley & Sons A/S.

  13. Exploring International Investment through a Classroom Portfolio Simulation Project

    Science.gov (United States)

    Chen, Xiaoying; Yur-Austin, Jasmine

    2013-01-01

    A rapid integration of financial markets has prevailed during the last three decades. Investors are able to diversify investment beyond national markets to mitigate return volatility of a "pure domestic portfolio." This article discusses a simulation project through which students learn the role of international investment by managing…

  14. Concept Development of the Eindhoven Diabetes Education Simulator Project

    NARCIS (Netherlands)

    Maas, Anne H.; van der Molen, Pieta; van de Vijver, Reinier; Chen, Wei; van Pul, Carola; Cottaar, Eduardus J. E.; van Riel, Natal A. W.; Hilbers, Peter A. J.; Haak, Harm R.

    2016-01-01

    Objective: This study was designed to define the concept of an educational diabetes game following a user-centered design approach. Materials and Methods: The concept development of the Eindhoven Diabetes Education Simulator (E-DES) project can be divided in two phases: concept generation and

  15. The SIMRAND methodology - Simulation of Research and Development Projects

    Science.gov (United States)

    Miles, R. F., Jr.

    1984-01-01

    In research and development projects, a commonly occurring management decision is concerned with the optimum allocation of resources to achieve the project goals. Because of resource constraints, management has to make a decision regarding the set of proposed systems or tasks which should be undertaken. SIMRAND (Simulation of Research and Development Projects) is a methodology which was developed for aiding management in this decision. Attention is given to a problem description, aspects of model formulation, the reduction phase of the model solution, the simulation phase, and the evaluation phase. The implementation of the considered approach is illustrated with the aid of an example which involves a simplified network of the type used to determine the price of silicon solar cells.

  16. Detection of Simulated Vertical Root Fractures: Which Cone-beam Computed Tomographic System Is the Most Accurate?

    Science.gov (United States)

    Elsaltani, Mohamed Hussein; Farid, Mary Medhat; Eldin Ashmawy, Mostafa Saad

    2016-06-01

    We aimed to compare the diagnostic accuracy of 5 cone-beam computed tomographic (CBCT) systems in detecting vertical root fractures (VRFs) and to assess whether fracture identification is affected by the presence of root canal filling. Eighty extracted posterior teeth were included in this study. They were grouped according to the presence/absence of VRFs and the presence/absence of endodontic treatment. The teeth were then inserted in 5 dry skull/mandible assemblies. CBCT scans were performed using 5 different commercially available systems. Two observers evaluated the resultant multiplanar images twice for VRFs using a 3-point scale. i-CAT (Imaging Sciences International, Hatfield, PA) showed the highest diagnostic accuracy in the detection of VRFs among the 5 investigated CBCT systems. The presence of root canal filling did not significantly decrease the ability to detect VRFs by all the studied systems. In the detection of VRFs in endodontically treated teeth, i-CAT was the most accurate, whereas 3D Accuitomo (J. Morita, Kyoto, Japan) was the least. Interobserver agreement was moderate for the i-CAT and fair for the rest of the studied modalities, whereas intraobserver agreement was good for the Scanora 3D (Soredex, Tuusula, Finland) and moderate for images from the other CBCT machines. At the specified exposure parameters in the detection of VRFs in non-root canal-filled teeth, i-CAT showed the highest diagnostic accuracy followed by Planmeca Promax 3D (Planmeca, Helsinki, Finland), Scanora 3D, Accuitomo 3D, and Galileos 3D (Sirona Dental Systems, Bensheim, Germany), respectively. In the detection of VRFs in root canal-filled teeth, i-CAT showed the highest diagnostic accuracy followed by Planmeca Promax 3D, Scanora 3D, Galileos Comfort (Sirona Dental Systems), and Accuitomo 3D. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Entrance surface dose distribution and organ dose assessment for cone-beam computed tomography using measurements and Monte Carlo simulations with voxel phantoms

    Science.gov (United States)

    Baptista, M.; Di Maria, S.; Vieira, S.; Vaz, P.

    2017-11-01

    Cone-Beam Computed Tomography (CBCT) enables high-resolution volumetric scanning of the bone and soft tissue anatomy under investigation at the treatment accelerator. This technique is extensively used in Image Guided Radiation Therapy (IGRT) for pre-treatment verification of patient position and target volume localization. When employed daily and several times per patient, CBCT imaging may lead to high cumulative imaging doses to the healthy tissues surrounding the exposed organs. This work aims at (1) evaluating the dose distribution during a CBCT scan and (2) calculating the organ doses involved in this image guiding procedure for clinically available scanning protocols. Both Monte Carlo (MC) simulations and measurements were performed. To model and simulate the kV imaging system mounted on a linear accelerator (Edge™, Varian Medical Systems) the state-of-the-art MC radiation transport program MCNPX 2.7.0 was used. In order to validate the simulation results, measurements of the Computed Tomography Dose Index (CTDI) were performed, using standard PMMA head and body phantoms, with 150 mm length and a standard pencil ionizing chamber (IC) 100 mm long. Measurements for head and pelvis scanning protocols, usually adopted in clinical environment were acquired, using two acquisition modes (full-fan and half fan). To calculate the organ doses, the implemented MC model of the CBCT scanner together with a male voxel phantom ("Golem") was used. The good agreement between the MCNPX simulations and the CTDIw measurements (differences up to 17%) presented in this work reveals that the CBCT MC model was successfully validated, taking into account the several uncertainties. The adequacy of the computational model to map dose distributions during a CBCT scan is discussed in order to identify ways to reduce the total CBCT imaging dose. The organ dose assessment highlights the need to evaluate the therapeutic and the CBCT imaging doses, in a more balanced approach, and the

  18. AmBe Final Project Report on Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Higginson, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schmidt, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Povilus, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-17

    In this project we examine the feasibility of using a dense plasma focus (DPF) to accelerate helium into a beryllium target as a way to replace AmBe sources with an accelerator source of similar neutron spectrum. Our group at LLNL, in collaboration with Voss Scientific, developed a fully kinetic model of DPF z-pinch plasmas in order to accurately predict ion beam spectra and neutron yields. Our group uses this tool as a guide for experiments, and also as a predictive tool to access regimes that would be time-consuming or expensive to try experimentally. In this report, we summarize the simulations that were performed during the course of this feasibility study. These simulations include the calculation of a DPF neutron spectrum based on a simulated ion beam spectrum, a pressure scan with optimized anode length, a sensitivity study to see how much the model depends on the MHD switch time, and initial simulations of the plasma breakdown.

  19. The simulation model of teleradiology in telemedicine project.

    Science.gov (United States)

    Goodini, Azadeh; Torabi, Mashallah; Goodarzi, Maryam; Safdari, Reza; Darayi, Mohamad; Tavassoli, Mahdieh; Shabani, MohammadMehdi

    2015-01-01

    Telemedicine projects are aimed at offering medical services to people who do not have access to direct diagnosis and treatment services. As a powerful tool for analyzing the performance of complex systems and taking probable events into consideration, systemic simulation can facilitate the analysis of implementation processes of telemedicine projects in real-life-like situations. The aim of the present study was to propose a model for planning resource capacities and allocating human and operational resources to promote the efficiency of telemedicine project by investigating the process of teleradiology. In this article, after verification of the conceptual model by the experts of this field, the computerized simulation model is developed using simulation software Arena. After specifying the required data, different improvement scenarios are run using the computerized model by feeding the data into the software and validation and verification of the model. Fixing input data of the system such as the number of patients, their waiting time, and process time of each function, for example, magnetic resonance imaging or scan, has been compared with the current radiology process. Implementing the teleradiology model resulted in reduction of time of patients in the system (current: 1.84 ± 0.00, tele: 0.81 ± 0.00). Furthermore, through this process, they can allocate the lower resources to perform better functions of staff. The use of computerized simulation is essential for designing processes, optimal allocation of resources, planning, and making appropriate decisions for providing timely services to patients.

  20. Community Petascale Project for Accelerator Science and Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Warren B. Mori

    2013-02-01

    The UCLA Plasma Simulation Group is a major partner of the "Community Petascale Project for Accelerator Science and Simulation. This is the final technical report. We include an overall summary, a list of publications and individual progress reports for each years. During the past five years we have made tremendous progress in enhancing the capabilities of OSIRIS and QuickPIC, in developing new algorithms and data structures for PIC codes to run on GPUS and many future core architectures, and in using these codes to model experiments and in making new scientific discoveries. Here we summarize some highlights for which SciDAC was a major contributor.

  1. Micro-motion Recognition of Spatial Cone Target Based on ISAR Image Sequences

    Directory of Open Access Journals (Sweden)

    Changyong Shu

    2016-04-01

    Full Text Available The accurate micro-motions recognition of spatial cone target is the foundation of the characteristic parameter acquisition. For this reason, a micro-motion recognition method based on the distinguishing characteristics extracted from the Inverse Synthetic Aperture Radar (ISAR sequences is proposed in this paper. The projection trajectory formula of cone node strong scattering source and cone bottom slip-type strong scattering sources, which are located on the spatial cone target, are deduced under three micro-motion types including nutation, precession, and spinning, and the correctness is verified by the electromagnetic simulation. By comparison, differences are found among the projection of the scattering sources with different micro-motions, the coordinate information of the scattering sources in the Inverse Synthetic Aperture Radar sequences is extracted by the CLEAN algorithm, and the spinning is recognized by setting the threshold value of Doppler. The double observation points Interacting Multiple Model Kalman Filter is used to separate the scattering sources projection of the nutation target or precession target, and the cross point number of each scattering source’s projection track is used to classify the nutation or precession. Finally, the electromagnetic simulation data are used to verify the effectiveness of the micro-motion recognition method.

  2. Comparative evaluation of a novel smart-seal obturating system and its homogeneity of using cone beam computed tomography: In vitro simulated lateral canal study.

    Science.gov (United States)

    Arora, Shashank; Hegde, Vibha

    2014-07-01

    The aim was to evaluate and compare a novel polyamide polymer based obturating system and Gutta-percha and sealer in filling simulated lateral canals and their homogeneity when used for obturating the root canals. A total of 60 freshly extracted human single rooted teeth with fully formed apices were selected for this study. Teeth were de-coronated, and roots were standardized to a working length of 15 mm. Root canal preparation was carried out with rotary Protaper file system in all groups. The specimens were then randomly divided into three groups A, B, and C (n = 20). Ten samples from each group were decalcified and simulated lateral canals were made at 2, 4, and 6 mm from the root apex. Remaining ten samples from each group were maintained calcified. Group A was obturated with SmartSeal system (Prosmart-DRFP Ltd., Stamford, UK). Group B was obturated with sectional backfill method. Group C was obutrated with cold lateral compaction method (control). Decalcified samples from the respective groups were analyzed with digital radiography and photography and the measurement of the linear extension and area of lateral canal filling was done using UTHSCSA (UTHSCSA Image Tool for Windows version 3.0, San Antonio, TX, USA) software. Calcified samples were subjected to cone beam computed tomography image analysis sectioned axially. Group A 92.46 ± 19.45 showed greatest extent of filling in lateral canals and denser homogeneity of oburation, followed by Group B 78.43 ± 26.45 and Group C 52.12 ± 36.67. Polyamide polymer obturation proved to have greater efficiency when compared with Gutta-percha system, when used for obturation with regards to adaptation of the sealer and penetration into the simulated lateral canals.

  3. Patient-specific scatter correction in clinical cone beam computed tomography imaging made possible by the combination of Monte Carlo simulations and a ray tracing algorithm

    DEFF Research Database (Denmark)

    Slot Thing, Rune; Bernchou, Uffe; Mainegra-Hing, Ernesto

    2013-01-01

    _cbct), was used to perform MC simulations of an Elekta XVI CBCT imaging system. A 60keV x-ray source was used, and air kerma scored at the detector plane. Several variance reduction techniques (VRTs) were used to increase the scatter calculation efficiency. Three patient phantoms based on CT scans were simulated...... being fully implemented in a clinical setting. This study investigates the combination of using fast MC simulations to predict scatter distributions with a ray tracing algorithm to allow calibration between simulated and clinical CBCT images. Material and methods. An EGSnrc-based user code (egs......, namely a brain, a thorax and a pelvis scan. A ray tracing algorithm was used to calculate the detector signal due to primary photons. A total of 288 projections were simulated, one for each thread on the computer cluster used for the investigation. Results. Scatter distributions for the brain, thorax...

  4. El proyecto subregional cono sur de control y vigilancia de la hidatidosis The southern cone sub-regional project on cystic echinococosis control and surveillance

    Directory of Open Access Journals (Sweden)

    Pilar Irabedra

    2010-12-01

    Full Text Available El Proyecto Subregional Cono Sur de Control y Vigilancia de la Hidatidosis: Argentina, Brasil, Chile y Uruguay, es una herramienta conjunta y colaborativa de los países para promover la implantación o el fortalecimiento de los programas de control. Se hace una descripción de los antecedentes, de los aspectos institucionales que regulan su organicidad y funcionamiento y de las líneas de acción definidas en el proyecto técnico operativo. Se destaca los logros obtenidos a través de los Proyectos de Cooperación Técnica entre Países así como el desarrollo de enfoques integrales e innovadores y la formación de recursos humanos de los programas de control. Algunos de los desafíos futuros son: lograr la sustentabilidad del Proyecto, implementar los grupos técnicos de análisis y evaluación a solicitud de los países, mejorar los sistemas de información regionales, continuar las actividades de capacitación y entrenamiento de recursos humanos y la expansión y fortalecimiento de la cooperación técnica entre países.Southern Cone Sub-Regional Project on Cystic Echinococcosis Control and Surveillance: Argentina, Brasil, Chile and Uruguay, is a joint and collaborative tool with the aim of promoting the implementation or the strengthening of programs for disease control. The paper describes the background, the institutional aspects that regulates the structure and functions, as well as the guidelines defined in the technical and operational project. The article emphasize the achievements through Projects of Technical Cooperation among Countries, and the development of integrated and innovative approaches for prevention and control of the disease and training of human resources of the control programs. Some of the challenges are: to achieve the sustainability of the project, implementation of technical groups for analysis and assessment at request of the countries, improvement of the regional information systems, to continue training human

  5. On-line use of three-dimensional marker trajectory estimation from cone-beam computed tomography projections for precise setup in radiotherapy for targets with respiratory motion.

    Science.gov (United States)

    Worm, Esben S; Høyer, Morten; Fledelius, Walther; Nielsen, Jens E; Larsen, Lars P; Poulsen, Per R

    2012-05-01

    To develop and evaluate accurate and objective on-line patient setup based on a novel semiautomatic technique in which three-dimensional marker trajectories were estimated from two-dimensional cone-beam computed tomography (CBCT) projections. Seven treatment courses of stereotactic body radiotherapy for liver tumors were delivered in 21 fractions in total to 6 patients by a linear accelerator. Each patient had two to three gold markers implanted close to the tumors. Before treatment, a CBCT scan with approximately 675 two-dimensional projections was acquired during a full gantry rotation. The marker positions were segmented in each projection. From this, the three-dimensional marker trajectories were estimated using a probability based method. The required couch shifts for patient setup were calculated from the mean marker positions along the trajectories. A motion phantom moving with known tumor trajectories was used to examine the accuracy of the method. Trajectory-based setup was retrospectively used off-line for the first five treatment courses (15 fractions) and on-line for the last two treatment courses (6 fractions). Automatic marker segmentation was compared with manual segmentation. The trajectory-based setup was compared with setup based on conventional CBCT guidance on the markers (first 15 fractions). Phantom measurements showed that trajectory-based estimation of the mean marker position was accurate within 0.3 mm. The on-line trajectory-based patient setup was performed within approximately 5 minutes. The automatic marker segmentation agreed with manual segmentation within 0.36 ± 0.50 pixels (mean ± SD; pixel size, 0.26 mm in isocenter). The accuracy of conventional volumetric CBCT guidance was compromised by motion smearing (≤21 mm) that induced an absolute three-dimensional setup error of 1.6 ± 0.9 mm (maximum, 3.2) relative to trajectory-based setup. The first on-line clinical use of trajectory estimation from CBCT projections for precise

  6. Quotient normed cones

    Indian Academy of Sciences (India)

    general setting of the space CL(X, Y ) of all continuous linear mappings from a normed cone (X, p) to a normed cone (Y, q), extending several well-known results related to open continuous linear mappings between normed linear spaces. Keywords. Normed cone; extended quasi-metric; continuous linear mapping; bicom-.

  7. Diagnostic accuracy of small volume cone beam computed tomography and intraoral periapical radiography for the detection of simulated external inflammatory root resorption.

    Science.gov (United States)

    Durack, C; Patel, S; Davies, J; Wilson, R; Mannocci, F

    2011-02-01

    To compare in an ex vivo model the ability of digital intraoral radiography and cone beam computed tomography (CBCT) to detect simulated external inflammatory root resorption lesions, and to investigate the effect of altering the degree of rotation of the CBCT scanners X-ray source and imaging detector on the ability to detect the same lesions. Small and large simulated external inflammatory resorption (EIR) lesions were created on the roots of 10 mandibular incisor teeth from three human mandibles. Small volume CBCT scans with 180° and 360° of X-ray source rotation and periapical radiographs, using a digital photostimulable phosphor plate system, were taken prior to and after the creation of the EIR lesions. The teeth were relocated in their original sockets during imaging. Receiver operator characteristic (ROC) analysis and kappa tests of the reproducibility of the imaging techniques were carried out and sensitivity, specificity, positive and negative predictive values (PPV and NPV) were also determined for each technique. The overall area under the ROC curve (Az value) for intraoral radiography was 0.665, compared to Az values of 0.984 and 0.990 for 180° and 360° CBCT, respectively (Pintraoral radiography (Pradiography. The intra- and inter-examiner agreement was significantly better for CBCT than it was for intraoral radiography (Pintraoral periapical radiography. Small volume CBCT operating with 360° of rotation of the X-ray source and detector is no better at detecting small, artificially created EIR cavities than the same device operating with 180° of rotation. © 2010 International Endodontic Journal.

  8. Activity modes selection for project crashing through deterministic simulation

    Directory of Open Access Journals (Sweden)

    Ashok Mohanty

    2011-12-01

    Full Text Available Purpose: The time-cost trade-off problem addressed by CPM-based analytical approaches, assume unlimited resources and the existence of a continuous time-cost function. However, given the discrete nature of most resources, the activities can often be crashed only stepwise. Activity crashing for discrete time-cost function is also known as the activity modes selection problem in the project management. This problem is known to be NP-hard. Sophisticated optimization techniques such as Dynamic Programming, Integer Programming, Genetic Algorithm, Ant Colony Optimization have been used for finding efficient solution to activity modes selection problem. The paper presents a simple method that can provide efficient solution to activity modes selection problem for project crashing.Design/methodology/approach: Simulation based method implemented on electronic spreadsheet to determine activity modes for project crashing. The method is illustrated with the help of an example.Findings: The paper shows that a simple approach based on simple heuristic and deterministic simulation can give good result comparable to sophisticated optimization techniques.Research limitations/implications: The simulation based crashing method presented in this paper is developed to return satisfactory solutions but not necessarily an optimal solution.Practical implications: The use of spreadsheets for solving the Management Science and Operations Research problems make the techniques more accessible to practitioners. Spreadsheets provide a natural interface for model building, are easy to use in terms of inputs, solutions and report generation, and allow users to perform what-if analysis.Originality/value: The paper presents the application of simulation implemented on a spreadsheet to determine efficient solution to discrete time cost tradeoff problem.

  9. 15 MW HArdware-in-the-loop Grid Simulation Project

    Energy Technology Data Exchange (ETDEWEB)

    Rigas, Nikolaos [Clemson Univ., SC (United States); Fox, John Curtiss [Clemson Univ., SC (United States); Collins, Randy [Clemson Univ., SC (United States); Tuten, James [Clemson Univ., SC (United States); Salem, Thomas [Clemson Univ., SC (United States); McKinney, Mark [Clemson Univ., SC (United States); Hadidi, Ramtin [Clemson Univ., SC (United States); Gislason, Benjamin [Clemson Univ., SC (United States); Boessneck, Eric [Clemson Univ., SC (United States); Leonard, Jesse [Clemson Univ., SC (United States)

    2014-10-31

    The 15MW Hardware-in-the-loop (HIL) Grid Simulator project was to (1) design, (2) construct and (3) commission a state-of-the-art grid integration testing facility for testing of multi-megawatt devices through a ‘shared facility’ model open to all innovators to promote the rapid introduction of new technology in the energy market to lower the cost of energy delivered. The 15 MW HIL Grid Simulator project now serves as the cornerstone of the Duke Energy Electric Grid Research, Innovation and Development (eGRID) Center. This project leveraged the 24 kV utility interconnection and electrical infrastructure of the US DOE EERE funded WTDTF project at the Clemson University Restoration Institute in North Charleston, SC. Additionally, the project has spurred interest from other technology sectors, including large PV inverter and energy storage testing and several leading edge research proposals dealing with smart grid technologies, grid modernization and grid cyber security. The key components of the project are the power amplifier units capable of providing up to 20MW of defined power to the research grid. The project has also developed a one of a kind solution to performing fault ride-through testing by combining a reactive divider network and a large power converter into a hybrid method. This unique hybrid method of performing fault ride-through analysis will allow for the research team at the eGRID Center to investigate the complex differences between the alternative methods of performing fault ride-through evaluations and will ultimately further the science behind this testing. With the final goal of being able to perform HIL experiments and demonstration projects, the eGRID team undertook a significant challenge with respect to developing a control system that is capable of communicating with several different pieces of equipment with different communication protocols in real-time. The eGRID team developed a custom fiber optical network that is based upon FPGA

  10. Performance Analysis of Cone Detection Algorithms

    CERN Document Server

    Mariotti, Letizia

    2015-01-01

    Many algorithms have been proposed to help clinicians evaluate cone density and spacing, as these may be related to the onset of retinal diseases. However, there has been no rigorous comparison of the performance of these algorithms. In addition, the performance of such algorithms is typically determined by comparison with human observers. Here we propose a technique to simulate realistic images of the cone mosaic. We use the simulated images to test the performance of two popular cone detection algorithms and we introduce an algorithm which is used by astronomers to detect stars in astronomical images. We use Free Response Operating Characteristic (FROC) curves to evaluate and compare the performance of the three algorithms. This allows us to optimize the performance of each algorithm. We observe that performance is significantly enhanced by up-sampling the images. We investigate the effect of noise and image quality on cone mosaic parameters estimated using the different algorithms, finding that the estimat...

  11. Dual energy approach for cone beam artifacts correction

    Science.gov (United States)

    Han, Chulhee; Choi, Shinkook; Lee, Changwoo; Baek, Jongduk

    2017-03-01

    Cone beam computed tomography systems generate 3D volumetric images, which provide further morphological information compared to radiography and tomosynthesis systems. However, reconstructed images by FDK algorithm contain cone beam artifacts when a cone angle is large. To reduce the cone beam artifacts, two-pass algorithm has been proposed. The two-pass algorithm considers the cone beam artifacts are mainly caused by high density materials, and proposes an effective method to estimate error images (i.e., cone beam artifacts images) by the high density materials. While this approach is simple and effective with a small cone angle (i.e., 5 - 7 degree), the correction performance is degraded as the cone angle increases. In this work, we propose a new method to reduce the cone beam artifacts using a dual energy technique. The basic idea of the proposed method is to estimate the error images generated by the high density materials more reliably. To do this, projection data of the high density materials are extracted from dual energy CT projection data using a material decomposition technique, and then reconstructed by iterative reconstruction using total-variation regularization. The reconstructed high density materials are used to estimate the error images from the original FDK images. The performance of the proposed method is compared with the two-pass algorithm using root mean square errors. The results show that the proposed method reduces the cone beam artifacts more effectively, especially with a large cone angle.

  12. An assessment of the efficiency of methods for measurement of the computed tomography dose index (CTDI) for cone beam (CBCT) dosimetry by Monte Carlo simulation.

    Science.gov (United States)

    Abuhaimed, Abdullah; J Martin, Colin; Sankaralingam, Marimuthu; J Gentle, David; McJury, Mark

    2014-11-07

    The IEC has introduced a practical approach to overcome shortcomings of the CTDI100 for measurements on wide beams employed for cone beam (CBCT) scans. This study evaluated the efficiency of this approach (CTDIIEC) for different arrangements using Monte Carlo simulation techniques, and compared CTDIIEC to the efficiency of CTDI100 for CBCT. Monte Carlo EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc codes were used to simulate the kV imaging system mounted on a Varian TrueBeam linear accelerator. The Monte Carlo model was benchmarked against experimental measurements and good agreement shown. Standard PMMA head and body phantoms with lengths 150, 600, and 900 mm were simulated. Beam widths studied ranged from 20-300 mm, and four scanning protocols using two acquisition modes were utilized. The efficiency values were calculated at the centre (εc) and periphery (εp) of the phantoms and for the weighted CTDI (εw). The efficiency values for CTDI100 were approximately constant for beam widths 20-40 mm, where εc(CTDI100), εp(CTDI100), and εw(CTDI100) were 74.7  ±  0.6%, 84.6  ±  0.3%, and 80.9  ±  0.4%, for the head phantom and 59.7  ±  0.3%, 82.1  ±  0.3%, and 74.9  ±  0.3%, for the body phantom, respectively. When beam width increased beyond 40 mm, ε(CTDI100) values fell steadily reaching ~30% at a beam width of 300 mm. In contrast, the efficiency of the CTDIIEC was approximately constant over all beam widths, demonstrating its suitability for assessment of CBCT. εc(CTDIIEC), εp(CTDIIEC), and εw(CTDIIEC) were 76.1  ±  0.9%, 85.9  ±  1.0%, and 82.2  ±  0.9% for the head phantom and 60.6  ±  0.7%, 82.8  ±  0.8%, and 75.8  ±  0.7%, for the body phantom, respectively, within 2% of ε(CTDI100) values for narrower beam widths. CTDI100,w and CTDIIEC,w underestimate CTDI∞,w by ~55% and ~18% for the head phantom and by ~56% and ~24% for the body phantom, respectively, using a clinical beam width 198 mm. The

  13. Motion tolerant iterative reconstruction algorithm for cone-beam helical CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hisashi; Goto, Taiga; Hirokawa, Koichi; Miyazaki, Osamu [Hitachi Medical Corporation, Chiba-ken (Japan). CT System Div.

    2011-07-01

    We have developed a new advanced iterative reconstruction algorithm for cone-beam helical CT. The features of this algorithm are: (a) it uses separable paraboloidal surrogate (SPS) technique as a foundation for reconstruction to reduce noise and cone-beam artifact, (b) it uses a view weight in the back-projection process to reduce motion artifact. To confirm the improvement of our proposed algorithm over other existing algorithm, such as Feldkamp-Davis-Kress (FDK) or SPS algorithm, we compared the motion artifact reduction, image noise reduction (standard deviation of CT number), and cone-beam artifact reduction on simulated and clinical data set. Our results demonstrate that the proposed algorithm dramatically reduces motion artifacts compared with the SPS algorithm, and decreases image noise compared with the FDK algorithm. In addition, the proposed algorithm potentially improves time resolution of iterative reconstruction. (orig.)

  14. An in vitro comparison of diagnostic accuracy of cone beam computed tomography and phosphor storage plate to detect simulated occlusal secondary caries under amalgam restoration

    Directory of Open Access Journals (Sweden)

    Shoaleh Shahidi

    2015-01-01

    Full Text Available Background: This study was aimed to compare the diagnostic accuracy and feasibility of cone beam computed tomography (CBCT with phosphor storage plate (PSP in detection of simulated occlusal secondary caries. Materials and Methods: In this in vitro descriptive-comparative study, a total of 80 slots of class I cavities were prepared on 80 extracted human premolars. Then, 40 teeth were randomly selected out of this sample and artificial carious lesions were created on these teeth by a round diamond bur no. 1/2. All 80 teeth were restored with amalgam fillings and radiographs were taken, both with PSP system and CBCT. All images were evaluated by three calibrated observers. The area under the receiver operating characteristic curve was used to compare the diagnostic accuracy of two systems. SPSS (SPSS Inc., Chicago, IL, USA was adopted for statistical analysis. The difference between Az value of bitewing and CBCT methods were compared by pairwise comparison method. The inter- and intra-operator agreement was assessed by kappa analysis (P < 0.05. Results: The mean A z value for bitewings and CBCT was 0.903 and 0.994, respectively. Significant differences were found between PSP and CBCT (P = 0.010. The kappa value for inter-observer agreement was 0.68 and 0.76 for PSP and CBCT, respectively. The kappa value for intra-observer agreement was 0.698 (observer 1, P = 0.000, 0.766 (observer 2, P = 0.000 and 0.716 (observer 3, P = 0.000 in PSP method, and 0.816 (observer 1, P = 0.000, 0.653 (observer 2, P = 0.000 and 0.744 (observer 3, P = 0.000 in CBCT method. Conclusion: This in vitro study, with a limited number of samples, showed that the New Tom VGI Flex CBCT system was more accurate than the PSP in detecting the simulated small secondary occlusal caries under amalgam restoration.

  15. Cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS flat panel detector: Visibility of simulated microcalcifications

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Youtao; Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C. [Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States)

    2013-10-15

    Purpose: To measure and investigate the improvement of microcalcification (MC) visibility in cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS/CsI flat panel detector (Dexela 2923, Perkin Elmer).Methods: Aluminum wires and calcium carbonate grains of various sizes were embedded in a paraffin cylinder to simulate imaging of calcifications in a breast. Phantoms were imaged with a benchtop experimental cone beam CT system at various exposure levels. In addition to the Dexela detector, a high pitch (50 μm), thin (150 μm) scintillator CMOS/CsI flat panel detector (C7921CA-09, Hamamatsu Corporation, Hamamatsu City, Japan) and a widely used low pitch (194 μm), thick (600 μm) scintillator aSi/CsI flat panel detector (PaxScan 4030CB, Varian Medical Systems) were also used in scanning for comparison. The images were independently reviewed by six readers (imaging physicists). The MC visibility was quantified as the fraction of visible MCs and measured as a function of the estimated mean glandular dose (MGD) level for various MC sizes and detectors. The modulation transfer functions (MTFs) and detective quantum efficiencies (DQEs) were also measured and compared for the three detectors used.Results: The authors have demonstrated that the use of a high pitch (75 μm) CMOS detector coupled with a thick (500 μm) CsI scintillator helped make the smaller 150–160, 160–180, and 180–200 μm MC groups more visible at MGDs up to 10.8, 9, and 10.8 mGy, respectively. It also made the larger 200–212 and 212–224 μm MC groups more visible at MGDs up to 7.2 mGy. No performance improvement was observed for 224–250 μm or larger size groups. With the higher spatial resolution of the Dexela detector based system, the apparent dimensions and shapes of MCs were more accurately rendered. The results show that with the aforementioned detector, a 73% visibility could be achieved in imaging 160–180 μm MCs as compared to 28% visibility achieved by

  16. Dynamic cone beam CT angiography of carotid and cerebral arteries using canine model

    Energy Technology Data Exchange (ETDEWEB)

    Cai Weixing; Zhao Binghui; Conover, David; Liu Jiangkun; Ning Ruola [Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States); Department of Radiology, Shanghai 6th People' s Hospital, 600 Yishan Road, Xuhui, Shanghai (China); Koning Corporation, Lennox Tech Enterprise Center, 150 Lucius Gordon Drive Suite 112, West Henrietta, New York 14586 (United States); Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States); Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States) and Koning Corporation, Lennox Tech Enterprise Center, 150 Lucius Gordon Drive Suite 112, West Henrietta, New York 14586 (United States)

    2012-01-15

    Purpose: This research is designed to develop and evaluate a flat-panel detector-based dynamic cone beam CT system for dynamic angiography imaging, which is able to provide both dynamic functional information and dynamic anatomic information from one multirevolution cone beam CT scan. Methods: A dynamic cone beam CT scan acquired projections over four revolutions within a time window of 40 s after contrast agent injection through a femoral vein to cover the entire wash-in and wash-out phases. A dynamic cone beam CT reconstruction algorithm was utilized and a novel recovery method was developed to correct the time-enhancement curve of contrast flow. From the same data set, both projection-based subtraction and reconstruction-based subtraction approaches were utilized and compared to remove the background tissues and visualize the 3D vascular structure to provide the dynamic anatomic information. Results: Through computer simulations, the new recovery algorithm for dynamic time-enhancement curves was optimized and showed excellent accuracy to recover the actual contrast flow. Canine model experiments also indicated that the recovered time-enhancement curves from dynamic cone beam CT imaging agreed well with that of an IV-digital subtraction angiography (DSA) study. The dynamic vascular structures reconstructed using both projection-based subtraction and reconstruction-based subtraction were almost identical as the differences between them were comparable to the background noise level. At the enhancement peak, all the major carotid and cerebral arteries and the Circle of Willis could be clearly observed. Conclusions: The proposed dynamic cone beam CT approach can accurately recover the actual contrast flow, and dynamic anatomic imaging can be obtained with high isotropic 3D resolution. This approach is promising for diagnosis and treatment planning of vascular diseases and strokes.

  17. Cones in Supersonic Flow

    Science.gov (United States)

    Hantzsche, W.; Wendt, H.

    1947-01-01

    In the case of cones in axially symmetric flow of supersonic velocity, adiabatic compression takes place between shock wave and surface of the cone. Interpolation curves betwen shock polars and the surface are therefore necessary for the complete understanding of this type of flow. They are given in the present report by graphical-numerical integration of the differential equation for all cone angles and airspeeds.

  18. NASA GRC UAS Project: Communications Modeling and Simulation Status

    Science.gov (United States)

    Kubat, Greg

    2013-01-01

    The integration of Unmanned Aircraft Systems (UAS) in the National Airspace represents new operational concepts required in civil aviation. These new concepts are evolving as the nation moves toward the Next Generation Air Transportation System (NextGen) under the leadership of the Joint Planning and Development Office (JPDO), and through ongoing work by the Federal Aviation Administration (FAA). The desire and ability to fly UAS in the National Air Space (NAS) in the near term has increased dramatically, and this multi-agency effort to develop and implement a national plan to successfully address the challenges of UAS access to the NAS in a safe and timely manner is well underway. As part of the effort to integrate UAS in the National Airspace, NASA Glenn Research Center is currently involved with providing research into Communications systems and Communication system operations in order to assist with developing requirements for this implementation. In order to provide data and information regarding communication systems performance that will be necessary, NASA GRC is tasked with developing and executing plans for simulations of candidate future UAS command and control communications, in line with architectures and communications technologies being developed and/or proposed by NASA and relevant aviation organizations (in particular, RTCA SC-203). The simulations and related analyses will provide insight into the ability of proposed communications technologies and system architectures to enable safe operation of UAS, meeting UAS in the NAS project goals (including performance requirements, scalability, and interoperability), and ultimately leading to a determination of the ability of NextGen communication systems to accommodate UAS. This presentation, compiled by the NASA GRC team, will provide a view of the overall planned simulation effort and objectives, a description of the simulation concept and status of the design and development that has occurred to date.

  19. NASA GRC UAS Project - Communications Modeling and Simulation Development Status

    Science.gov (United States)

    Apaza, Rafael; Bretmersky, Steven; Dailey, Justin; Satapathy, Goutam; Ditzenberger, David; Ye, Chris; Kubat, Greg; Chevalier, Christine; Nguyen, Thanh

    2014-01-01

    The integration of Unmanned Aircraft Systems (UAS) in the National Airspace represents new operational concepts required in civil aviation. These new concepts are evolving as the nation moves toward the Next Generation Air Transportation System (NextGen) under the leadership of the Joint Planning and Development Office (JPDO), and through ongoing work by the Federal Aviation Administration (FAA). The desire and ability to fly UAS in the National Air Space (NAS) in the near term has increased dramatically, and this multi-agency effort to develop and implement a national plan to successfully address the challenges of UAS access to the NAS in a safe and timely manner is well underway. As part of the effort to integrate UAS in the National Airspace, NASA Glenn Research Center is currently involved with providing research into Communications systems and Communication system operations in order to assist with developing requirements for this implementation. In order to provide data and information regarding communication systems performance that will be necessary, NASA GRC is tasked with developing and executing plans for simulations of candidate future UAS command and control communications, in line with architectures and communications technologies being developed and or proposed by NASA and relevant aviation organizations (in particular, RTCA SC-203). The simulations and related analyses will provide insight into the ability of proposed communications technologies and system architectures to enable safe operation of UAS, meeting UAS in the NAS project goals (including performance requirements, scalability, and interoperability), and ultimately leading to a determination of the ability of NextGen communication systems to accommodate UAS. This presentation, compiled by the NASA GRC Modeling and Simulation team, will provide an update to this ongoing effort at NASA GRC as follow-up to the overview of the planned simulation effort presented at ICNS in 2013. The objective

  20. Start To End Simulation for the SPARX Project

    CERN Document Server

    Vaccarezza, Cristina; Boscolo, Manuela; Ferrario, Massimo; Fusco, Valeria; Giannessi, Luca; Migliorati, Mauro; Palumbo, Luigi; Quattromini, Marcello; Ronsivalle, Concetta; Serafini, Luca; Spataro, Bruno; Vescovi, Mario

    2005-01-01

    The first phase of the SPARX project now funded by Government Agencies, is an R&D activity focused on developing techniques and critical components for future X-ray facilities. The aim is the generation of electron beams with the ultra-high peak brightness required to drive FEL experiments. The FEL source realization will develop along two lines: (a) the use of the SPARC high brightness photoinjector to test RF compression techniques and the emittance degradation in magnetic compressors due to CSR, (b) the production of radiation in the range of 3-5 nm, both in SASE and SEEDED FEL configurations, in the so called SPARXINO test facility, upgrading the existing Frascati 800 MeV LINAC. In this paper we present and discuss the preliminary start to end simulations results.

  1. Computer simulations for minds-on learning with ``Project Spectra!''

    Science.gov (United States)

    Wood, E. L.; Renfrow, S.; Marks, N.; Christofferson, R.

    2010-12-01

    How do we gain information about the Sun? How do we know Mars has CO2 or that Titan has a nitrogen-rich atmosphere? How do we use light in astronomy? These concepts are something education professionals generally struggle with because they are abstract. Making use of visualizations and presenting material so it can be manipulated is the easiest way to conquer abstractions to bring them home to students. Using simulations and computer interactives (games) where students experience and manipulate the information makes concepts accessible. “Project Spectra!” is a science and engineering program that uses computer-based Flash interactives to expose students to astronomical spectroscopy and actual data in a way that is not possible with traditional in-class activities. Visualizing lessons with multi-media is a way to solidify understanding and retention of knowledge and is completely unlike its paper-and-pencil counterpart. To engage students in “Project Spectra!”, students are given a mission, which connects them with the research at hand. Missions range from exploring remote planetary atmospheres and surfaces, experimenting with the Sun using different filters, and comparing spectroscopic atmospheric features between different bodies. Additionally, students have an opportunity to learn about NASA missions, view movies, and see images connected with their mission. In the end, students are asked critical thinking questions and conduct web-based research. These interactives complement the in-class activities where students engineer spectrographs and explore the electromagnetic spectrum.

  2. Software development infrastructure for the HYBRID modeling and simulation project

    Energy Technology Data Exchange (ETDEWEB)

    Epiney, Aaron S. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kinoshita, Robert A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kim, Jong Suk [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Greenwood, M. Scott [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    One of the goals of the HYBRID modeling and simulation project is to assess the economic viability of hybrid systems in a market that contains renewable energy sources like wind. The idea is that it is possible for the nuclear plant to sell non-electric energy cushions, which absorb (at least partially) the volatility introduced by the renewable energy sources. This system is currently modeled in the Modelica programming language. To assess the economics of the system, an optimization procedure is trying to find the minimal cost of electricity production. The RAVEN code is used as a driver for the whole problem. It is assumed that at this stage, the HYBRID modeling and simulation framework can be classified as non-safety “research and development” software. The associated quality level is Quality Level 3 software. This imposes low requirements on quality control, testing and documentation. The quality level could change as the application development continues.Despite the low quality requirement level, a workflow for the HYBRID developers has been defined that include a coding standard and some documentation and testing requirements. The repository performs automated unit testing of contributed models. The automated testing is achieved via an open-source python script called BuildingsP from Lawrence Berkeley National Lab. BuildingsPy runs Modelica simulation tests using Dymola in an automated manner and generates and runs unit tests from Modelica scripts written by developers. In order to assure effective communication between the different national laboratories a biweekly videoconference has been set-up, where developers can report their progress and issues. In addition, periodic face-face meetings are organized intended to discuss high-level strategy decisions with management. A second means of communication is the developer email list. This is a list to which everybody can send emails that will be received by the collective of the developers and managers

  3. Appreciating the Complexity of Project Management Execution: Using Simulation in the Classroom

    Science.gov (United States)

    Hartman, Nathan S.; Watts, Charles A.; Treleven, Mark D.

    2013-01-01

    As the popularity and importance of project management increase, so does the need for well-prepared project managers. This article discusses our experiences using a project management simulation in undergraduate and MBA classes to help students better grasp the complexity of project management. This approach gives students hands-on experience with…

  4. The SCAR project - accidental thermal-hydraulics: from the simulation to the simulators; Le projet scar-thermohydraulique accidentelle: de la simulation aux simulateurs

    Energy Technology Data Exchange (ETDEWEB)

    Farvacque, M.; Faydide, B.; Parent, M.; Iffenecker, F.; Pentori, B.; Dumas, J.M

    2000-07-01

    The integration of the CATHARE code in the reactor simulators was completed in the beginning of the years 1990 with the design of the simulators SIPA1 and SIPA2. The SCAR project (Simulator CAthare Release), presented in this paper, is the following of this application. The objective is the adaptation of a reference CATHARE code version to the simulators environment, in order to realize the convergence between the safety analysis tool and the simulator. (A.L.B.)

  5. Ion beam focusing with cone optics for WDM experiments

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Jun, E-mail: jun.hasegawa@es.titech.ac.jp [Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Kondo, Kotaro; Oguri, Yoshiyuki [Research Laboratory for Nuclear Reactors, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Horioka, Kazuhiko [Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)

    2014-01-01

    Beam focusing properties of cone optics were systematically investigated by Monte Carlo simulations under various combinations of beam and cone parameters. To optimize the cone optic design for accelerator-driven WDM experiments, the beam intensity gains after cone focusing were evaluated from the simulation results as functions of cone wall material and shape parameters such as taper angle and wall curvature. The uniformity of the cone-focused beam was also examined by considering not only various cone parameters but also the cases involving the misalignment of the cone optic. From the results, a parabolic gold cone was found to be the best choice at least for relatively light ions such as lithium having MeV energies. It is also found that although smaller taper angle improves the total beam transport efficiency in the optic, it brings more difficulties in the alignment of the optic because the alignment accuracy should be less than a half of the taper angle to obtain acceptable uniformity in the beam energy deposition on the target.

  6. Evaluation of cumulative dose for cone-beam computed tomography (CBCT) scans within phantoms made from different compositions using Monte Carlo simulations.

    Science.gov (United States)

    Abuhaimed, Abdullah; Martin, Colin J; Sankaralingam, Marimuthu; Oomen, Kurian; Gentle, David J

    2015-11-08

    Measurement of cumulative dose ƒ(0,150) with a small ionization chamber within standard polymethyl methacrylate (PMMA) CT head and body phantoms, 150 mm in length, is a possible practical method for cone-beam computed tomography (CBCT) dosimetry. This differs from evaluating cumulative dose under scatter equilibrium conditions within an infinitely long phantom ƒ(0,∞), which is proposed by AAPM TG-111 for CBCT dosimetry. The aim of this study was to investigate the feasibility of using ƒ(0,150) to estimate values for ƒ(0,∞) in long head and body phantoms made of PMMA, polyethylene (PE), and water, using beam qualities for tube potentials of 80-140 kV. The study also investigated the possibility of using 150 mm PE phantoms for assessment of ƒ(0,∞) within long PE phantoms, the ICRU/AAPM phantom. The influence of scan parameters, composition, and length of the phantoms was investigated. The capability of ƒ(0,150) to assess ƒ(0,∞) has been defined as the efficiency and assessed in terms of the ratios ε(ƒ(0,150) / ƒ(0,∞)). The efficiencies were calculated using Monte Carlo simulations for an On-Board Imager (OBI) system mounted on a TrueBeam linear accelerator. Head and body scanning protocols with beams of width 40-500 mm were used. Efficiencies ε(PMMA/PMMA) and ε(PE/PE) as a function of beam width exhibited three separate regions. For beam widths phantoms. The efficiency values then fell rapidly with increasing beam width before levelling off at 74% for ε(PMMA/PMMA) and 69% for ε(PE/PE) for a 500 mm beam width. The quantities ε(PMMA/PE) and ε(PMMA/Water) varied with beam width in a different manner. Values at the centers of the phantoms for narrow beams were lower and increased to a steady state for ~100-150 mm wide beams, before declining with increasing the beam width, whereas values at the peripheries decreased steadily with beam width. Results for ε(PMMA/PMMA) were virtually independent of tube potential, but there was more variation for

  7. Simulation of inverters for the PHOTONERGY{sup TM} project. Development and simulation of new topologies

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-11-01

    The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into the specifications. Based on these two documents, a set of 23 topologies was analysed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies are in this report further investigated by means of an initial design-iteration and simulations. The items of interest in this report are efficiency and component ratings (magnetics, transistors, diodes and capacitors). The simulations reveal that DC-to-DC converters (for amplifying the PV-Module voltage) build on resonant technology (series-resonant and parallel-resonant) all suffers from high circulating currents inside the resonant tank; qua a low efficiency is the result. Whereas, the standard full-bridge converter and the novel MOHAN converter do not suffers from these severe currents, which also reflects into a higher efficiency. The ratings for the resonant converters are also somewhat larger than for the two other solutions. The two selected DC/DC converters are, on the basis of these properties, the standard full-bridge converter and the MOHAN converter. The simulated DC-to-AC inverters (for modulating the sinusoidal grid current) both show excellent performance in terms of high efficiency and low ratings. However, it seems that the MOSFET equipped inverters has lower losses than the IGBT equipped one. The last inverter investigated is the novel Dual FlyBack Inverter, which both amplifies the PV-Module voltage and modulates the sinusoidal grid current in one single process. Unfortunately, this circuit suffers from a low efficiency due to a high internal current. However, the efficiency is expected to increase with an increasing switching frequency, so the inverter is also selected for further design. A novel 'single-step' solution emerged at the end of the period: the

  8. Airspace Simulation Through Indoor Operation of Subscale Flight Vehicles Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An indoor environment for simulating airspace operations will be designed. Highly maneuverable subscale vehicles can be used to simulate the dynamics of full-scale...

  9. Deep Space Navigation and Timing Architecture and Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Microcosm team will complete the simulation tool architecture early in Phase II, and in parallel begin to develop the simulation. The tool is architected for...

  10. Optimization of Cone Beam CT Reconstruction Algorithm Based on CUDA

    National Research Council Canada - National Science Library

    Wang Li-Fang; Zhang Shu-Hai

    2013-01-01

    .... This paper optimizes cone beam CT reconstruction algorithm by CUDA and improves the speed of weighted back-projection and filtering, and shortens the data access time by using the texture memory...

  11. SU-G-BRA-10: Marker Free Lung Tumor Motion Tracking by An Active Contour Model On Cone Beam CT Projections for Stereotactic Body Radiation Therapy of Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Chao, M; Yuan, Y; Lo, Y [The Mount Sinai Medical Center, New York, NY (United States); Wei, J [City College of New York, New York, NY (United States)

    2016-06-15

    Purpose: To develop a novel strategy to extract the lung tumor motion from cone beam CT (CBCT) projections by an active contour model with interpolated respiration learned from diaphragm motion. Methods: Tumor tracking on CBCT projections was accomplished with the templates derived from planning CT (pCT). There are three major steps in the proposed algorithm: 1) The pCT was modified to form two CT sets: a tumor removed pCT and a tumor only pCT, the respective digitally reconstructed radiographs DRRtr and DRRto following the same geometry of the CBCT projections were generated correspondingly. 2) The DRRtr was rigidly registered with the CBCT projections on the frame-by-frame basis. Difference images between CBCT projections and the registered DRRtr were generated where the tumor visibility was appreciably enhanced. 3) An active contour method was applied to track the tumor motion on the tumor enhanced projections with DRRto as templates to initialize the tumor tracking while the respiratory motion was compensated for by interpolating the diaphragm motion estimated by our novel constrained linear regression approach. CBCT and pCT from five patients undergoing stereotactic body radiotherapy were included in addition to scans from a Quasar phantom programmed with known motion. Manual tumor tracking was performed on CBCT projections and was compared to the automatic tracking to evaluate the algorithm accuracy. Results: The phantom study showed that the error between the automatic tracking and the ground truth was within 0.2mm. For the patients the discrepancy between the calculation and the manual tracking was between 1.4 and 2.2 mm depending on the location and shape of the lung tumor. Similar patterns were observed in the frequency domain. Conclusion: The new algorithm demonstrated the feasibility to track the lung tumor from noisy CBCT projections, providing a potential solution to better motion management for lung radiation therapy.

  12. Assessment of radiation exposure in dental cone-beam computerized tomography with the use of metal-oxide semiconductor field-effect transistor (MOSFET) dosimeters and Monte Carlo simulations.

    Science.gov (United States)

    Koivisto, J; Kiljunen, T; Tapiovaara, M; Wolff, J; Kortesniemi, M

    2012-09-01

    The aims of this study were to assess the organ and effective dose (International Commission on Radiological Protection (ICRP) 103) resulting from dental cone-beam computerized tomography (CBCT) imaging using a novel metal-oxide semiconductor field-effect transistor (MOSFET) dosimeter device, and to assess the reliability of the MOSFET measurements by comparing the results with Monte Carlo PCXMC simulations. Organ dose measurements were performed using 20 MOSFET dosimeters that were embedded in the 8 most radiosensitive organs in the maxillofacial and neck area. The dose-area product (DAP) values attained from CBCT scans were used for PCXMC simulations. The acquired MOSFET doses were then compared with the Monte Carlo simulations. The effective dose measurements using MOSFET dosimeters yielded, using 0.5-cm steps, a value of 153 μSv and the PCXMC simulations resulted in a value of 136 μSv. The MOSFET dosimeters placed in a head phantom gave results similar to Monte Carlo simulations. Minor vertical changes in the positioning of the phantom had a substantial affect on the overall effective dose. Therefore, the MOSFET dosimeters constitute a feasible method for dose assessment of CBCT units in the maxillofacial region. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Enhanced Mesh-Free Simulation of Regolith Flow Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA needs simulation tools capable of predicting the behavior of regolith in proposed excavation, transport, and handling or sample acquisition systems. For...

  14. Simulation Software's Effect on College Students Spreadsheet Project Scores

    Science.gov (United States)

    Atkinson, J. Kirk; Thrasher, Evelyn H.; Coleman, Phillip D.

    2011-01-01

    The purpose of this study is to explore the potential impact of support materials on student spreadsheet skill acquisition. Specifically, this study examines the use of an online spreadsheet simulation tool versus a printed book across two independent student groups. This study hypothesizes that the online spreadsheet simulation tool will have a…

  15. Computer simulation of GaAs and SOI devices using TCAD tools: an REU project

    OpenAIRE

    Goel, Ashok; Bergstrom, Sarah; Mojica-Campbell, Aleli

    1999-01-01

    An undergraduate research project is outlined whose goal was to use the TCAD tools to simulate the performances of GaAs- and SOI-based devices and to compare them with the corresponding silicon-based devices. Students used the Silvaco Corporation's "Virtual Wafer Fab" (VWF) package consisting of process simulation software called ATHENA, device layout software called DevEdit and device simulation software called ATLAS to simulate GaAs, SOI as well as conventional silicon devices. They explore...

  16. GPU-Based 3D Cone-Beam CT Image Reconstruction for Large Data Volume

    Directory of Open Access Journals (Sweden)

    Xing Zhao

    2009-01-01

    Full Text Available Currently, 3D cone-beam CT image reconstruction speed is still a severe limitation for clinical application. The computational power of modern graphics processing units (GPUs has been harnessed to provide impressive acceleration of 3D volume image reconstruction. For extra large data volume exceeding the physical graphic memory of GPU, a straightforward compromise is to divide data volume into blocks. Different from the conventional Octree partition method, a new partition scheme is proposed in this paper. This method divides both projection data and reconstructed image volume into subsets according to geometric symmetries in circular cone-beam projection layout, and a fast reconstruction for large data volume can be implemented by packing the subsets of projection data into the RGBA channels of GPU, performing the reconstruction chunk by chunk and combining the individual results in the end. The method is evaluated by reconstructing 3D images from computer-simulation data and real micro-CT data. Our results indicate that the GPU implementation can maintain original precision and speed up the reconstruction process by 110–120 times for circular cone-beam scan, as compared to traditional CPU implementation.

  17. Vision and Displays for Military and Security Applications The Advanced Deployable Day/Night Simulation Project

    CERN Document Server

    Niall, Keith K

    2010-01-01

    Vision and Displays for Military and Security Applications presents recent advances in projection technologies and associated simulation technologies for military and security applications. Specifically, this book covers night vision simulation, semi-automated methods in photogrammetry, and the development and evaluation of high-resolution laser projection technologies for simulation. Topics covered include: advances in high-resolution projection, advances in image generation, geographic modeling, and LIDAR imaging, as well as human factors research for daylight simulation and for night vision devices. This title is ideal for optical engineers, simulator users and manufacturers, geomatics specialists, human factors researchers, and for engineers working with high-resolution display systems. It describes leading-edge methods for human factors research, and it describes the manufacture and evaluation of ultra-high resolution displays to provide unprecedented pixel density in visual simulation.

  18. IMPROVING PROJECT SCHEDULE ESTIMATES USING HISTORICAL DATA AND SIMULATION

    Directory of Open Access Journals (Sweden)

    P.H. Meyer

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: Many projects are not completed on time or within the original budget. This is caused by uncertainty in project variables as well as the occurrence of risk events. A study was done to determine ways of measuring the risk in development projects executed by a mining company in South Africa. The main objective of the study was to determine whether historical project data would provide a more accurate means of estimating the total project duration. Original estimates and actual completion times for tasks of a number of projects were analysed and compared. The results of the study indicated that a more accurate total duration for a project could be obtained by making use of historical project data. The accuracy of estimates could be improved further by building a comprehensive project schedule database within a specific industry.

    AFRIKAANSE OPSOMMING: Verskeie projekte word nie binne die oorspronklike skedule of begroting voltooi nie. Dit word dikwels veroorsaak deur onsekerheid oor projekveranderlikes en die voorkoms van risiko’s. 'n Studie is gedoen om 'n metode te ontwikkel om risiko te meet vir ontwikkelingsprojekte van 'n mynmaatskappy in Suid Afrika. Die hoofdoel van die studie was om te bepaal of historiese projekdata gebruik kon word om 'n akkurater tydsduur vir 'n projek te beraam. Die geraamde tydsduur van take vir 'n aantal projekte is ontleed en vergelyk met die werklike tydsduur. Die resultate van die studie het getoon dat 'n akkurater totale tydsduur vir die projek verkry kon word deur gebruik te maak van historiese projekdata. Die akkuraatheid kan verder verbeter word deur 'n databasis van projekskedules vir 'n bepaalde industrie te ontwikkel en by datum te hou.

  19. Simulator for Optimization of Software Project Cost and Schedule

    OpenAIRE

    Suri, P. K.; Bhushan, B.

    2008-01-01

    Each phase of the software design consumes some resources and hence has cost associated with it. In most of the cases cost will vary to some extent with the amount of time consumed by the design of each phase .The total cost of project, which is aggregate of the activities costs will also depends upon the project duration, can be cut down to some extent. The aim is always to strike a balance between the cost and time and to obtain an optimum software project schedule. An optimum minimum cost ...

  20. Insulin receptor signaling in cones

    National Research Council Canada - National Science Library

    Rajala, Ammaji; Dighe, Radhika; Agbaga, Martin-Paul; Anderson, Robert E; Rajala, Raju V S

    2013-01-01

    .... To date there are no studies on the insulin receptor signaling in cones; however, mRNA levels of IR signaling proteins are significantly higher in cone-dominant neural retina leucine zipper (Nrl...

  1. Aeroelastic Simulation Tool for Inflatable Ballute Aerocapture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop a much-needed multidisciplinary analysis tool for predicting the impact of aeroelastic effects on the functionality of inflatable...

  2. Simulation Environment for Power Management and Distribution Development Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall objective of this research project is to investigate autonomous control architectures for spacecraft power systems. Such techniques will be critical for...

  3. Simulating Nonlinear Dynamics of Deployable Space Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To support NASA's vital interest in developing much larger solar array structures over the next 20 years, MotionPort LLC's Phase I SBIR project will strengthen...

  4. Simulation Environment for Power Management and Distribution Development Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall objective of this research project is to investigate an autonomous and online control structure for finite-inertia power systems (dc and ac) with a...

  5. A Student Project to use Geant4 Simulations for a TMS-PET combination

    Science.gov (United States)

    Altamirano, A.; Chamorro, A.; Hurtado, K.; Romero, C.; Rueda, A.; Solano Salinas, C. J.; Wahl, D.; Zamudio, A.

    2007-10-01

    Geant4 is one of the most powerful tools for MC simulation of detectors and their applications. We present a student project to simulate a combined Transcranial Magnetic Stimulation-Positron Emission Tomography (TMS-PET) system using Geant4. This project aims to study PET-TMS systems by implementing a model for the brain response to the TMS pulse and studying the simulated PET response. In order to increase the speed of the simulations we parallelise our programs and investigate the possibility of using GRID computing.

  6. A SIMULATION BASED APPROACH FOR AN INVESTMENT PROJECT EVALUATION UNDER UNCERTAIN AND RISKY ENVIRONMENTS

    Directory of Open Access Journals (Sweden)

    Özgür YALÇINKAYA

    2010-06-01

    Full Text Available Under high uncertainty and risky environments, the future estimations related to project proposalscannot be certain and really materialized values. It is inevitable that there exists a deviation or gap betweenforecasted values and actual values. Thus, project risk level of the proposal should be analyzedin the assessment phase. Simulation based project evaluation approaches enables to make more reliableinvestment decision since they permits including future uncertainty and risk in analyze process. Inaddition, many times, project proposals are evaluated with more than one conflicted criteria. The aimof this paper is to present a new approach that accounts for multiple objectives for evaluating riskyinvestment projects and determining projects risk level. With the proposed simulation based optimizationapproach, necessity values for project parameters are determined to reach the expected profitabilityof the investment with the minimum initial investment cost. Also, there is an illustrative examplegiven in this study as an application of the proposed approach.

  7. The eddy-eliminating method of guide cone in the closed sump

    Science.gov (United States)

    Wang, Y. J.; Cheng, L.; Xia, C. Z.; Zhou, J. R.; Yan, H. Q.; Jiang, H. Y.

    2016-05-01

    In order to explore the effect on eddy-eliminating method of guide cone in the closed sump, the simple factor analysis and CFD numerical simulation are applied to calculate the flow field of closed sump and select ω-shaped back wall. ω-shaped back wall is consistent with the stream line in the suction sump, on this basis, CFD numerical simulation is conducted with the eddy-eliminating of the triangle guide cone and traditional guide cone. The results show that, for eddy-eliminating measures, with the height of triangular guide cone from 0 to 0.407HZ/DL , the excessive triangle guide cone hinder water into the flared pipe. With the width of triangular guide cone from 0.5 to 1.0BZ/DL , increasing width of triangular guide cone may increase the pumping hydraulic performance and pumping efficiency. However with the width of triangular guide cone from 0.5 to 1.0 BZ/DL , too broad traditional guide cone hinder water into the flared pipe. In the design discharge, whether triangle guide cone or traditional guide cone have a little effect on the efficiency of the pumping station. But in terms of the eddy-eliminating on the bottom of suction sump, it is necessary to set up guide cone.

  8. Production of Mature Highland Lunar Regolith Simulant Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As NASA considers manned and/or unmanned return missions to the Moon and beyond, it is imperative that high fidelity lunar soil simulants be developed in order to...

  9. Simulation Approach to Mission Risk and Reliability Analysis Project

    Data.gov (United States)

    National Aeronautics and Space Administration — It is proposed to develop and demonstrate an integrated total-system risk and reliability analysis approach that is based on dynamic, probabilistic simulation. This...

  10. Industrial Scale Production of Celestial Body Simulants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objectives of this program are to develop a cost-effective process to deliver Celestial body simulants for the foreseeable future. Specifically, the...

  11. Deep Space Navigation and Timing Architecture and Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Microcosm will develop a deep space navigation and timing architecture and associated simulation, incorporating state-of-the art radiometric, x-ray pulsar, and laser...

  12. Unified Nonlinear Flight Dynamics and Aeroelastic Simulator Tool Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes a R&D effort to develop a Unified Nonlinear Flight Dynamics and Aeroelastic Simulator (UNFDAS) Tool that will combine...

  13. Thermal Mapping Airborne Simulator for Small Satellite Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A high performance, inexpensive, airborne simulator that will serve as the prototype for a small satellite based imaging system capable of mapping thermal anomalies...

  14. Mass Production of Mature Lunar Regolith Simulant Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As NASA prepares for future exploration activities on the Moon, there is a growing need to develop higher fidelity lunar soil simulants that can accurately reproduce...

  15. Building Blocks for the Rapid Development of Parallel Simulations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Scientists need to be able to quickly develop and run parallel simulations without paying the high price of writing low-level message passing codes using compiled...

  16. High Fidelity Regolith Simulation Tool for ISRU Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has serious unmet needs for simulation tools capable of predicting the behavior of lunar regolith in proposed excavation, transport and handling systems....

  17. Optimal Rendezvous and Docking Simulator for Elliptical Orbits Project

    Data.gov (United States)

    National Aeronautics and Space Administration — It is proposed to develop and implement a simulation of spacecraft rendezvous and docking guidance, navigation, and control in elliptical orbit. The foundation of...

  18. Software Infrastructure to Enable Modeling & Simulation as a Service (M&SaaS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 2 project will produce a software service infrastructure that enables most modeling and simulation (M&S) activities from code development and...

  19. Finite Coverings by Cones

    NARCIS (Netherlands)

    Tijs, S.H.; Reijnierse, J.H.

    2001-01-01

    This paper considers analogues of statements concerning compactness and finite coverings, in which the roles of spheres are replaced by cones. Furthermore, one of the finite covering results provides an application in Multi-Objective Programming; infinite sets of alternatives are reduced to finite

  20. Markerless four-dimensional-cone beam computed tomography projection-phase sorting using prior knowledge and patient motion modeling: A feasibility study

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2017-01-01

    Conclusion: The study demonstrated the feasibility of using PCA coefficients for 4D-CBCT projection-phase sorting. High sorting accuracy in both digital phantoms and patient cases was achieved. This method provides an accurate and robust tool for automatic 4D-CBCT projection sorting using 3D motion modeling without the need of external surrogate or internal markers.

  1. Role-play Simulation of Building Design Projects.

    Science.gov (United States)

    Holgate, Alan

    1987-01-01

    Describes the development of an "executive game" which is designed to give students of civil engineering some impression of the wider context of the design of a building project in which the client, architect, contractor, regulatory authorities and community interest groups all play a part. (CW)

  2. Comparing cone beam laminographic system trajectories for composite NDT

    Directory of Open Access Journals (Sweden)

    Neil O'Brien

    2016-11-01

    Full Text Available We compare the quality of reconstruction obtainable using various laminographic system trajectories that have been described in the literature, with reference to detecting defects in composite materials in engineering. We start by describing a laminar phantom representing a simplified model of composite panel, which models certain defects that may arise in such materials, such as voids, resin rich areas, and delamination, and additionally features both blind and through holes along multiple axes. We simulate ideal cone-beam projections of this phantom with the different laminographic trajectories, applying both Simultaneous Iterative Reconstruction Technique (SIRT and Conjugate Gradient Least Squares (CGLS reconstruction algorithms. We compare the quality of the reconstructions with a view towards optimising the scan parameters for defect detectability in composite NDT applications.

  3. Electroacoustical simulation of listening room acoustics for project ARCHIMEDES

    DEFF Research Database (Denmark)

    Bech, Søren

    1989-01-01

    the influence of listening room acoustics on the timbre of reproduced sound. For simulation of the acoustics of a standard listening room, an electroacoustic setup has been built in an anechoic chamber. The setup is based on a computer model of the listening room, and it consists of a number of loudspeakers...

  4. Comprehensive Evaluations of Cone-beam CT dose in Image-guided Radiation Therapy via GPU-based Monte Carlo simulations

    CERN Document Server

    Montanari, Davide; Silvestri, Chiara; Graves, Yan J; Yan, Hao; Cervino, Laura; Rice, Roger; Jiang, Steve B; Jia, Xun

    2013-01-01

    Cone beam CT (CBCT) has been widely used for patient setup in image guided radiation therapy (IGRT). Radiation dose from CBCT scans has become a clinical concern. The purposes of this study are 1) to commission a GPU-based Monte Carlo (MC) dose calculation package gCTD for Varian On-Board Imaging (OBI) system and test the calculation accuracy, and 2) to quantitatively evaluate CBCT dose from the OBI system in typical IGRT scan protocols. We first conducted dose measurements in a water phantom. X-ray source model parameters used in gCTD are obtained through a commissioning process. gCTD accuracy is demonstrated by comparing calculations with measurements in water and in CTDI phantoms. 25 brain cancer patients are used to study dose in a standard-dose head protocol, and 25 prostate cancer patients are used to study dose in pelvis protocol and pelvis spotlight protocol. Mean dose to each organ is calculated. Mean dose to 2% voxels that have the highest dose is also computed to quantify the maximum dose. It is fo...

  5. Ejecta evolution during cone impact

    KAUST Repository

    Marston, Jeremy

    2014-07-07

    We present findings from an experimental investigation into the impact of solid cone-shaped bodies onto liquid pools. Using a variety of cone angles and liquid physical properties, we show that the ejecta formed during the impact exhibits self-similarity for all impact speeds for very low surface tension liquids, whilst for high-surface tension liquids similarity is only achieved at high impact speeds. We find that the ejecta tip can detach from the cone and that this phenomenon can be attributed to the air entrainment phenomenon. We analyse of a range of cone angles, including some ogive cones, and impact speeds in terms of the spatiotemporal evolution of the ejecta tip. Using superhydrophobic cones, we also examine the entry of cones which entrain an air layer.

  6. Process Modelling Support for the Conceptual Modelling Phase of a Simulation Project

    OpenAIRE

    Heavey, Cathal; Ryan, John

    2006-01-01

    While many developments have taken place around supportingthe model coding task of simulation, there are few toolsavailable to assist in the conceptual modelling phase. Severalauthors have reported the advantages of using processmodelling tools in the early phases of a simulation project.This paper provides an overview of process modelling toolsin relation to their support for simulation, categorizing thetools into formal method and descriptive methods. A conclusionfrom this review is that no...

  7. Three Dimensional Projection Environment for Molecular Design and Surgical Simulation

    Science.gov (United States)

    2011-08-01

    an artificial haptic response to Phacoemulsification cataract surgery simulation to enhance training effectiveness. However, the complex geometry...Role of Haptic Feedback in Cataract Surgery Train-ing", Medicine Meets Virtual Reality (MMVR) 15, 2008. [2] Salisbury, Z., Zilles, B., Salisbury, K...2011) Diagnostic and therapeutic imaging for cancer: therapeutic considerations and future directions. J Surg Oncol 103(6):587-601. PMID: 21480253

  8. Development of a full ice-cream cone model for halo CME structures

    Science.gov (United States)

    Na, Hyeonock; Moon, Yong-Jae

    2015-04-01

    The determination of three dimensional parameters (e.g., radial speed, angular width, source location) of Coronal Mass Ejections (CMEs) is very important for space weather forecast. To estimate these parameters, several cone models based on a flat cone or a shallow ice-cream cone with spherical front have been suggested. In this study, we investigate which cone model is proper for halo CME morphology using 33 CMEs which are identified as halo CMEs by one spacecraft (SOHO or STEREO-A or B) and as limb CMEs by the other ones. From geometrical parameters of these CMEs such as their front curvature, we find that near full ice-cream cone CMEs (28 events) are dominant over shallow ice-cream cone CMEs (5 events). So we develop a new full ice-cream cone model by assuming that a full ice-cream cone consists of many flat cones with different heights and angular widths. This model is carried out by the following steps: (1) construct a cone for given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, (4) minimize the difference between the estimated projection points with the observed ones. We apply this model to several halo CMEs and compare the results with those from other methods such as a Graduated Cylindrical Shell model and a geometrical triangulation method.

  9. Simulated Annealing Genetic Algorithm Based Schedule Risk Management of IT Outsourcing Project

    Directory of Open Access Journals (Sweden)

    Fuqiang Lu

    2017-01-01

    Full Text Available IT outsourcing is an effective way to enhance the core competitiveness for many enterprises. But the schedule risk of IT outsourcing project may cause enormous economic loss to enterprise. In this paper, the Distributed Decision Making (DDM theory and the principal-agent theory are used to build a model for schedule risk management of IT outsourcing project. In addition, a hybrid algorithm combining simulated annealing (SA and genetic algorithm (GA is designed, namely, simulated annealing genetic algorithm (SAGA. The effect of the proposed model on the schedule risk management problem is analyzed in the simulation experiment. Meanwhile, the simulation results of the three algorithms GA, SA, and SAGA show that SAGA is the most superior one to the other two algorithms in terms of stability and convergence. Consequently, this paper provides the scientific quantitative proposal for the decision maker who needs to manage the schedule risk of IT outsourcing project.

  10. Fast Simulation of X-ray Projections of Spline-based Surfaces using an Append Buffer

    Science.gov (United States)

    Maier, Andreas; Hofmann, Hannes G.; Schwemmer, Chris; Hornegger, Joachim; Keil, Andreas; Fahrig, Rebecca

    2012-01-01

    Many scientists in the field of x-ray imaging rely on the simulation of x-ray images. As the phantom models become more and more realistic, their projection requires high computational effort. Since x-ray images are based on transmission, many standard graphics acceleration algorithms cannot be applied to this task. However, if adapted properly, simulation speed can be increased dramatically using state-of-the-art graphics hardware. A custom graphics pipeline that simulates transmission projections for tomographic reconstruction was implemented based on moving spline surface models. All steps from tessellation of the splines, projection onto the detector, and drawing are implemented in OpenCL. We introduced a special append buffer for increased performance in order to store the intersections with the scene for every ray. Intersections are then sorted and resolved to materials. Lastly, an absorption model is evaluated to yield an absorption value for each projection pixel. Projection of a moving spline structure is fast and accurate. Projections of size 640×480 can be generated within 254 ms. Reconstructions using the projections show errors below 1 HU with a sharp reconstruction kernel. Traditional GPU-based acceleration schemes are not suitable for our reconstruction task. Even in the absence of noise, they result in errors up to 9 HU on average, although projection images appear to be correct under visual examination. Projections generated with our new method are suitable for the validation of novel CT reconstruction algorithms. For complex simulations, such as the evaluation of motion-compensated reconstruction algorithms, this kind of x-ray simulation will reduce the computation time dramatically. Source code is available at http://conrad.stanford.edu/ PMID:22975431

  11. SciDAC - Center for Plasma Edge Simulation - Project Summary

    Energy Technology Data Exchange (ETDEWEB)

    Parker, Scott [Univ. of Colorado, Boulder, CO (United States)

    2014-11-03

    Final Technical Report: Center for Plasma Edge Simulation (CPES) Principal Investigator: Scott Parker, University of Colorado, Boulder Description/Abstract First-principle simulations of edge pedestal micro-turbulence are performed with the global gyrokinetic turbulence code GEM for both low and high confinement tokamak plasmas. The high confinement plasmas show a larger growth rate, but nonlinearly a lower particle and heat flux. Numerical profiles are obtained from the XGC0 neoclassical code. XGC0/GEM code coupling is implemented under the EFFIS (“End-to-end Framework for Fusion Integrated Simulation”) framework. Investigations are underway to clearly identify the micro-instabilities in the edge pedestal using global and flux-tube gyrokinetic simulation with realistic experimental high confinement profiles. We use both experimental profiles and those obtained using the EFFIS XGC0/GEM coupled code framework. We find there are three types of instabilities at the edge: a low-n, high frequency electron mode, a high-n, low frequency ion mode, and possibly an ion mode like kinetic ballooning mode (KBM). Investigations are under way for the effects of the radial electric field. Finally, we have been investigating how plasmas dominated by ion-temperature gradient (ITG) driven turbulence, how cold Deuterium and Tritium ions near the edge will naturally pinch radially inward towards the core. We call this mechanism “natural fueling.” It is due to the quasi-neutral heat flux dominated nature of the turbulence and still applies when trapped and passing kinetic electron effects are included. To understand this mechanism, examine the situation where the electrons are adiabatic, and there is an ion heat flux. In such a case, lower energy particles move inward and higher energy particles move outward. If a trace amount of cold particles are added, they will move inward.

  12. Simulation and experimental studies of three-dimensional (3D) image reconstruction from insufficient sampling data based on compressed-sensing theory for potential applications to dental cone-beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Je, U.K.; Lee, M.S.; Cho, H.S., E-mail: hscho1@yonsei.ac.kr; Hong, D.K.; Park, Y.O.; Park, C.K.; Cho, H.M.; Choi, S.I.; Woo, T.H.

    2015-06-01

    In practical applications of three-dimensional (3D) tomographic imaging, there are often challenges for image reconstruction from insufficient sampling data. In computed tomography (CT), for example, image reconstruction from sparse views and/or limited-angle (<360°) views would enable fast scanning with reduced imaging doses to the patient. In this study, we investigated and implemented a reconstruction algorithm based on the compressed-sensing (CS) theory, which exploits the sparseness of the gradient image with substantially high accuracy, for potential applications to low-dose, high-accurate dental cone-beam CT (CBCT). We performed systematic simulation works to investigate the image characteristics and also performed experimental works by applying the algorithm to a commercially-available dental CBCT system to demonstrate its effectiveness for image reconstruction in insufficient sampling problems. We successfully reconstructed CBCT images of superior accuracy from insufficient sampling data and evaluated the reconstruction quality quantitatively. Both simulation and experimental demonstrations of the CS-based reconstruction from insufficient data indicate that the CS-based algorithm can be applied directly to current dental CBCT systems for reducing the imaging doses and further improving the image quality.

  13. Comparison of Asymmetric and Ice-cream Cone Models for Halo Coronal Mass Ejections

    Science.gov (United States)

    Na, H.; Moon, Y.

    2011-12-01

    Halo coronal mass ejections (HCMEs) are major cause of the geomagnetic storms. To minimize the projection effect by coronagraph observation, several cone models have been suggested: an ice-cream cone model, an asymmetric cone model etc. These models allow us to determine the three dimensional parameters of HCMEs such as radial speed, angular width, and the angle between sky plane and central axis of the cone. In this study, we compare these parameters obtained from different models using 48 well-observed HCMEs from 2001 to 2002. And we obtain the root mean square error (RMS error) between measured projection speeds and calculated projection speeds for both cone models. As a result, we find that the radial speeds obtained from the models are well correlated with each other (R = 0.86), and the correlation coefficient of angular width is 0.6. The correlation coefficient of the angle between sky plane and central axis of the cone is 0.31, which is much smaller than expected. The reason may be due to the fact that the source locations of the asymmetric cone model are distributed near the center, while those of the ice-cream cone model are located in a wide range. The average RMS error of the asymmetric cone model (85.6km/s) is slightly smaller than that of the ice-cream cone model (87.8km/s).

  14. Simulation-supported POD for ultrasonic testing. Recommendations from the PICASSO project

    Energy Technology Data Exchange (ETDEWEB)

    Baron, Hans-Uwe; Henkel, Benjamin [MTU Aero Engines AG, Muenchen (Germany); Bellon, Carsten; Deresch, Andreas [BAM Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany)

    2013-07-01

    The objective of the European project PICASSO (Improved reliability inspection of aeronautic structures by simulation-supported POD) was to build a new and original concept of simulation-supported Probability of Detection (POD) curves based on Non Destructive Testing simulations. This new methodology is based on the replacement of some of the experimental data with simulation results to obtain accurate and reliable POD curves with significantly less personnel and material costs. The present paper presents the main results of the PICASSO project for ultrasonic testing and addresses the most crucial aspects of the new approach, e.g. the definition of the noise level, the validation of the modeling tools, the combination of experimental and numerical data, and the specification of the uncertainty parameters and their statistical distribution. From the results recommendations for the practical use of simulation-supported POD curves are given.

  15. Simulated hydroclimatic impacts of projected Brazilian sugarcane expansion

    Science.gov (United States)

    Georgescu, M.; Lobell, D. B.; Field, C. B.; Mahalov, A.

    2013-03-01

    Sugarcane area is currently expanding in Brazil, largely in response to domestic and international demand for sugar-based ethanol. To investigate the potential hydroclimatic impacts of future expansion, a regional climate model is used to simulate 5 years of a scenario in which cerrado and cropland areas (~1.1E6 km2) within south-central Brazil are converted to sugarcane. Results indicate a cooling of up to ~1.0°C during the peak of the growing season, mainly as a result of increased albedo of sugarcane relative to the previous landscape. After harvest, warming of similar magnitude occurs from a significant decline in evapotranspiration and a repartitioning toward greater sensible heating. Overall, annual temperature changes from large-scale conversion are expected to be small because of offsetting reductions in net radiation absorption and evapotranspiration. The decline in net water flux from land to the atmosphere implies a reduction in regional precipitation, which is consistent with progressively decreasing simulated average rainfall for the study period, upon conversion to sugarcane. However, rainfall changes were not robust across three ensemble members. The results suggest that sugarcane expansion will not drastically alter the regional energy or water balance, but could result in important local and seasonal effects.

  16. CERN Summer Student Project Report – Simulation of the Micromegas Detector

    CERN Document Server

    Soares Ferreira Nunes Teixeira, Sofia Luisa

    2015-01-01

    My project during the Summer Student Programme at CERN consisted on simulations of the Micromegas (MM) detectors in order to test and characterize them in the presence of contamination by air of the gas mixture. The MM detectors were chosen for the upcoming upgrade of the ATLAS detector. The motivation for this project and the results obtained are here presented. Moreover, the work that should be carried out after this programme as a continuation of this project is also referred. To conclude, final considerations about the project are presented.

  17. Cone rod dystrophies

    Directory of Open Access Journals (Sweden)

    Hamel Christian P

    2007-02-01

    Full Text Available Abstract Cone rod dystrophies (CRDs (prevalence 1/40,000 are inherited retinal dystrophies that belong to the group of pigmentary retinopathies. CRDs are characterized by retinal pigment deposits visible on fundus examination, predominantly localized to the macular region. In contrast to typical retinitis pigmentosa (RP, also called the rod cone dystrophies (RCDs resulting from the primary loss in rod photoreceptors and later followed by the secondary loss in cone photoreceptors, CRDs reflect the opposite sequence of events. CRD is characterized by primary cone involvement, or, sometimes, by concomitant loss of both cones and rods that explains the predominant symptoms of CRDs: decreased visual acuity, color vision defects, photoaversion and decreased sensitivity in the central visual field, later followed by progressive loss in peripheral vision and night blindness. The clinical course of CRDs is generally more severe and rapid than that of RCDs, leading to earlier legal blindness and disability. At end stage, however, CRDs do not differ from RCDs. CRDs are most frequently non syndromic, but they may also be part of several syndromes, such as Bardet Biedl syndrome and Spinocerebellar Ataxia Type 7 (SCA7. Non syndromic CRDs are genetically heterogeneous (ten cloned genes and three loci have been identified so far. The four major causative genes involved in the pathogenesis of CRDs are ABCA4 (which causes Stargardt disease and also 30 to 60% of autosomal recessive CRDs, CRX and GUCY2D (which are responsible for many reported cases of autosomal dominant CRDs, and RPGR (which causes about 2/3 of X-linked RP and also an undetermined percentage of X-linked CRDs. It is likely that highly deleterious mutations in genes that otherwise cause RP or macular dystrophy may also lead to CRDs. The diagnosis of CRDs is based on clinical history, fundus examination and electroretinogram. Molecular diagnosis can be made for some genes, genetic counseling is

  18. Low-Gravity Mimicking Simulants and Evaluation of Simulant Flow Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will provide a new method for testing flow/no-flow conditions and other gravity-driven flow behavior of Lunar or planetary regolith under reduced...

  19. Determination of HCME 3-D parameters using a full ice-cream cone model

    Science.gov (United States)

    Na, Hyeonock; Moon, Yong-Jae; Lee, Harim

    2016-05-01

    It is very essential to determine three dimensional parameters (e.g., radial speed, angular width, source location) of Coronal Mass Ejections (CMEs) for space weather forecast. Several cone models (e.g., an elliptical cone model, an ice-cream cone model, an asymmetric cone model) have been examined to estimate these parameters. In this study, we investigate which cone type is close to a halo CME morphology using 26 CMEs: halo CMEs by one spacecraft (SOHO or STEREO-A or B) and as limb CMEs by the other ones. From cone shape parameters of these CMEs such as their front curvature, we find that near full ice-cream cone type CMEs are much closer to observations than shallow ice-cream cone type CMEs. Thus we develop a new cone model in which a full ice-cream cone consists of many flat cones with different heights and angular widths. This model is carried out by the following steps: (1) construct a cone for given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO/LASCO halo CMEs, we find that 3-D parameters from our method are similar to those from other stereoscopic methods (a geometrical triangulation method and a Graduated Cylindrical Shell model) based on multi-spacecraft data. We are developing a general ice-cream cone model whose front shape is a free parameter determined by observations.

  20. Scenario Based Education as a Framework for Understanding Students Engagement and Learning in a Project Management Simulation Game

    Science.gov (United States)

    Misfeldt, Morten

    2015-01-01

    In this paper I describe how students use a project management simulation game based on an attack-defense mechanism where two teams of players compete by challenging each other's projects. The project management simulation game is intended to be played by pre-service construction workers and engineers. The gameplay has two parts: a planning part,…

  1. Comprehensive Simulation Lifecycle Management for High Performance Computing Modeling and Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — There are significant logistical barriers to entry-level high performance computing (HPC) modeling and simulation (M&S) users. Performing large-scale, massively...

  2. Analytic image reconstruction from partial data for a single-scan cone-beam CT with scatter correction

    Energy Technology Data Exchange (ETDEWEB)

    Min, Jonghwan; Pua, Rizza; Cho, Seungryong, E-mail: scho@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Kim, Insoo; Han, Bumsoo [EB Tech, Co., Ltd., 550 Yongsan-dong, Yuseong-gu, Daejeon 305-500 (Korea, Republic of)

    2015-11-15

    Purpose: A beam-blocker composed of multiple strips is a useful gadget for scatter correction and/or for dose reduction in cone-beam CT (CBCT). However, the use of such a beam-blocker would yield cone-beam data that can be challenging for accurate image reconstruction from a single scan in the filtered-backprojection framework. The focus of the work was to develop an analytic image reconstruction method for CBCT that can be directly applied to partially blocked cone-beam data in conjunction with the scatter correction. Methods: The authors developed a rebinned backprojection-filteration (BPF) algorithm for reconstructing images from the partially blocked cone-beam data in a circular scan. The authors also proposed a beam-blocking geometry considering data redundancy such that an efficient scatter estimate can be acquired and sufficient data for BPF image reconstruction can be secured at the same time from a single scan without using any blocker motion. Additionally, scatter correction method and noise reduction scheme have been developed. The authors have performed both simulation and experimental studies to validate the rebinned BPF algorithm for image reconstruction from partially blocked cone-beam data. Quantitative evaluations of the reconstructed image quality were performed in the experimental studies. Results: The simulation study revealed that the developed reconstruction algorithm successfully reconstructs the images from the partial cone-beam data. In the experimental study, the proposed method effectively corrected for the scatter in each projection and reconstructed scatter-corrected images from a single scan. Reduction of cupping artifacts and an enhancement of the image contrast have been demonstrated. The image contrast has increased by a factor of about 2, and the image accuracy in terms of root-mean-square-error with respect to the fan-beam CT image has increased by more than 30%. Conclusions: The authors have successfully demonstrated that the

  3. Project ARGO: Gas phase formation in simulated microgravity

    Science.gov (United States)

    Powell, Michael R.; Waligora, James M.; Norfleet, William T.; Kumar, K. Vasantha

    1993-01-01

    The ARGO study investigated the reduced incidence of joint pain decompression sickness (DCS) encountered in microgravity as compared with an expected incidence of joint pain DCS experienced by test subjects in Earth-based laboratories (unit gravity) with similar protocols. Individuals who are decompressed from saturated conditions usually acquire joint pain DCS in the lower extremities. Our hypothesis is that the incidence of joint pain DCS can be limited by a significant reduction in the tissue gas micronuclei formed by stress-assisted nucleation. Reductions in dynamic and kinetic stresses in vivo are linked to hypokinetic and adynamic conditions of individuals in zero g. We employed the Doppler ultrasound bubble detection technique in simulated microgravity studies to determine quantitatively the degree of gas phase formation in the upper and lower extremities of test subjects during decompression. We found no evidence of right-to-left shunting through pulmonary vasculature. The volume of gas bubble following decompression was examined and compared with the number following saline contrast injection. From this, we predict a reduced incidence of DCS on orbit, although the incidence of predicted mild DCS still remains larger than that encountered on orbit.

  4. Prototyping a coherent framework for full, fast and parameteric detector simulation for the FCC project

    CERN Document Server

    Hrdinka, Julia; Salzburger, Andreas; Hegner, Benedikt

    2015-01-01

    The outstanding success of the physics program of the Large Hadron Collider (LHC) including the discovery of the Higgs boson shifted the focus of part of the high energy physics community onto the planning phase for future circular collider (FCC) projects. A proton-proton collider is in consideration, as well as an electron-positron ring and an electron-proton option as potential LHC successor projects. Common to all projects is the need for a coherent software framework in order to carry out simulation studies to establish the potential physics reach or to test different technol- ogy approaches. Detector simulation is a particularly necessary tool needed for design studies of different detector concepts and to allow establishing the relevant performance parameters. In ad- dition, it allows to generate data as input for the development of reconstruction algorithms needed to cope with the expected future environments. We present a coherent framework that combines full, fast and parametric detector simulation e...

  5. Simulation-based valuation of project finance investments. Crucial aspects of power plant projects

    Energy Technology Data Exchange (ETDEWEB)

    Pietz, Matthaeus

    2010-12-15

    The liberalization of electricity markets transformed a regulated and stable market to a market with former unknown price volatility. This results in a high uncertainty which is mainly due to the, from an economic point of view, lack of storability of the commodity electricity. Thus investments in power plants are highly risky. This dissertation analyzes crucial aspects within the valuation of a power plant financed via project finance, a popular financing method for projects with high capital requirements. Starting with the development of a valuation model based on stochastic modelling of the future cash flows the focus of the analysis is on the impact of model complexity and electricity prices. (orig.)

  6. A simulation study on the focal plane detector of the LAUE project

    Science.gov (United States)

    Khalil, M.; Frontera, F.; Caroli, E.; Virgilli, E.; Valsan, V.

    2015-06-01

    The LAUE project, supported by the Italian Space Agency (ASI), is devoted to the development of a long focal length (even 20 m or longer) Laue lens for gamma ray astronomy between 80 and 600 keV. These lenses take advantage of Bragg diffraction to focus radiation onto a small spot drastically improving the signal to noise ratio as well as reducing the required size of the detector significantly. In this paper we present a Monte-Carlo simulation study with MEGALIB to optimize, for space applications, the detector size to achieve high detection efficiency, and to optimize the position resolution of the detector to reconstruct the Point Spread Function of the lens considered for the LAUE project. Then we will show simulations, using the SILVACO semiconductor simulation toolkit, on the optimized detector to estimate its capacitance per channel and depletion voltage. In all of the simulations, two materials were compared; a low density material (Silicon) and a high density material (Germanium).

  7. A Strategy for Autogeneration of Space Shuttle Ground Processing Simulation Models for Project Makespan Estimations

    Science.gov (United States)

    Madden, Michael G.; Wyrick, Roberta; O'Neill, Dale E.

    2005-01-01

    Space Shuttle Processing is a complicated and highly variable project. The planning and scheduling problem, categorized as a Resource Constrained - Stochastic Project Scheduling Problem (RC-SPSP), has a great deal of variability in the Orbiter Processing Facility (OPF) process flow from one flight to the next. Simulation Modeling is a useful tool in estimation of the makespan of the overall process. However, simulation requires a model to be developed, which itself is a labor and time consuming effort. With such a dynamic process, often the model would potentially be out of synchronization with the actual process, limiting the applicability of the simulation answers in solving the actual estimation problem. Integration of TEAMS model enabling software with our existing schedule program software is the basis of our solution. This paper explains the approach used to develop an auto-generated simulation model from planning and schedule efforts and available data.

  8. Testing the reliability of ice-cream cone model

    Science.gov (United States)

    Pan, Zonghao; Shen, Chenglong; Wang, Chuanbing; Liu, Kai; Xue, Xianghui; Wang, Yuming; Wang, Shui

    2015-04-01

    Coronal Mass Ejections (CME)'s properties are important to not only the physical scene itself but space-weather prediction. Several models (such as cone model, GCS model, and so on) have been raised to get rid of the projection effects within the properties observed by spacecraft. According to SOHO/ LASCO observations, we obtain the 'real' 3D parameters of all the FFHCMEs (front-side full halo Coronal Mass Ejections) within the 24th solar cycle till July 2012, by the ice-cream cone model. Considering that the method to obtain 3D parameters from the CME observations by multi-satellite and multi-angle has higher accuracy, we use the GCS model to obtain the real propagation parameters of these CMEs in 3D space and compare the results with which by ice-cream cone model. Then we could discuss the reliability of the ice-cream cone model.

  9. Modeling and Simulation Optimization and Feasibility Studies for the Neutron Detection without Helium-3 Project

    Energy Technology Data Exchange (ETDEWEB)

    Ely, James H.; Siciliano, Edward R.; Swinhoe, Martyn T.; Lintereur, Azaree T.

    2013-01-01

    This report details the results of the modeling and simulation work accomplished for the ‘Neutron Detection without Helium-3’ project during the 2011 and 2012 fiscal years. The primary focus of the project is to investigate commercially available technologies that might be used in safeguards applications in the relatively near term. Other technologies that are being developed may be more applicable in the future, but are outside the scope of this study.

  10. Risk Assessment in Financial Feasibility of Tanker Project Using Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    Muhammad Badrus Zaman

    2017-09-01

    Full Text Available Every ship project would not be apart from risk and uncertainty issues. The inappropriate risk assessment process would have long-term impact, such as financial loss. Thus, risk and uncertainties analysis would be a very important process in financial feasibility determination of the project. This study analyzes the financial feasibility of 17,500 LTDW tanker project. Risk and uncertainty are two differentiated terminologies in this study, where risk focuses on operational risk due to shipbuilding process nonconformity to shipowner finance, while uncertainty focuses on variable costs that affect project cash flows. There are three funding scenarios in this study, where the percentage of funding with own capital and bank loan in scenario 1 is 100% : 0%, scenario 2 is 75% : 25%, and scenario 3 is 50% : 50%. Monte Carlo simulation method was applied to simulate the acceptance criteria, such as net present value (NPV, internal rate of return (IRR, payback period (PP, and profitability index (PI. The results of simulation show that 17,500 LTDW tanker project funding by scenario 1, 2 and 3 are feasible to run, where probability of each acceptance criteria was greater than 50%. Charter rate being the most sensitive uncertainty over project's financial feasibility parameters.

  11. Use of Monte Carlo simulation software for the calculation of the effective dose in cone beam Tomography; Uso del software de simulacion Monte Carlo para el calculo de la dosis efectiva en Tomografia de haz conico

    Energy Technology Data Exchange (ETDEWEB)

    Gomes B, W. O., E-mail: wilsonottobatista@gmail.com [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Bardalho, 40301-015 Salvador, Bahia (Brazil)

    2015-10-15

    Full text: In this study irradiation geometry applicable to PCXMC and the consequent calculation of effective dose in applications of cone beam computed tomography (CBCT) was developed. Two different CBCT equipment s for dental applications were evaluated: Care Stream Cs-9000 3-Dimensional and Gendex GXCB-500 tomographs. Each protocol initially was characterized by measuring the surface kerma input and the product air kerma-area, P{sub KA}. Then, technical parameters of each of the predetermined protocols and geometric conditions in the PCXMC software were introduced to obtain the values of effective dose. The calculated effective dose is within the range of 9.0 to 15.7 μSv for Cs 9000 3-D and in the range 44.5 to 89 mSv for GXCB-500 equipment. These values were compared with dosimetric results obtained using thermoluminescent dosimeters implanted in anthropomorphic mannequin and were considered consistent. The effective dose results are very sensitive to the radiation geometry (beam position); this represents a factor of fragility software usage, but on the other hand, turns out to be a very useful tool for quick conclusions regarding the optimization process of protocols. We can conclude that the use of Monte Carlo simulation software PCXMC is useful in the evaluation of test protocols of CBCT in dental applications. (Author)

  12. Singularities of plane complex curves and limits of Kähler metrics with cone singularities. I: Tangent Cones

    Directory of Open Access Journals (Sweden)

    Borbon Martin de

    2017-02-01

    Full Text Available The goal of this article is to provide a construction and classification, in the case of two complex dimensions, of the possible tangent cones at points of limit spaces of non-collapsed sequences of Kähler-Einstein metrics with cone singularities. The proofs and constructions are completely elementary, nevertheless they have an intrinsic beauty. In a few words; tangent cones correspond to spherical metrics with cone singularities in the projective line by means of the Kähler quotient construction with respect to the S1-action generated by the Reeb vector field, except in the irregular case ℂβ₁×ℂβ₂ with β₂/ β₁ ∉ Q.

  13. Dynamics of turtle cones.

    Science.gov (United States)

    Naka, K I; Itoh, M A; Chappell, R L

    1987-02-01

    The response dynamics of turtle photoreceptors (cones) were studied by the cross-correlation method using a white-noise-modulated light stimulus. Incremental responses were characterized by the kernels. White-noise-evoked responses with a peak-to-peak excursion of greater than 5 mV were linear, with mean square errors of approximately 8%, a degree of linearity comparable to the horizontal cell responses. Both a spot (0.17 mm diam) and a large field of light produced almost identical kernels. The amplitudes of receptor kernels obtained at various mean irradiances fitted approximately the Weber-Fechner relationship and the mean levels controlled both the amplitude and the response dynamics; kernels were slow and monophasic at low mean irradiance and were fast and biphasic at high mean irradiance. This is a parametric change and is a piecewise linearization. Horizontal cell kernels evoked by the small spot of light were monophasic and slower than the receptor kernels produced by the same stimulus. Larger spots of light or a steady annular illumination transformed the slow horizontal cell kernel into a fast kernel similar to those of the receptors. The slowing down of the kernel waveform was modeled by a simple low-pass circuit and the presumed feedback from horizontal cells onto cones did not appear to play a major role.

  14. Prediction of transparency perception based on cone-excitation ratios

    Science.gov (United States)

    Ripamonti, Caterina; Westland, Stephen

    2003-09-01

    Perceptual transparency was measured in two experiments by using simulations of illuminated surfaces presented on a CRT monitor. In a two-alternative forced-choice paradigm, observers viewed two simulated Mondrians in temporal sequence. In one sequence the Mondrian was simulated to be partially covered by a transparent filter; in the other sequence the filter color over each Mondrian patch was modified. Observers were instructed to select the sequence containing a transparent filter. Observers' selections corresponded to sequences in which the cone-excitation ratios for each adjacent pair of Mondrian patches were approximately the same as the cone-excitation ratios for the pair of patches covered by a filter. The results suggest that cone-excitation ratios may be a cue for perceptual transparency.

  15. Projections of Future Precipitation Extremes Over Europe: A Multimodel Assessment of Climate Simulations

    Science.gov (United States)

    Rajczak, Jan; Schär, Christoph

    2017-10-01

    Projections of precipitation and its extremes over the European continent are analyzed in an extensive multimodel ensemble of 12 and 50 km resolution EURO-CORDEX Regional Climate Models (RCMs) forced by RCP2.6, RCP4.5, and RCP8.5 (Representative Concentration Pathway) aerosol and greenhouse gas emission scenarios. A systematic intercomparison with ENSEMBLES RCMs is carried out, such that in total information is provided for an unprecedentedly large data set of 100 RCM simulations. An evaluation finds very reasonable skill for the EURO-CORDEX models in simulating temporal and geographical variations of (mean and heavy) precipitation at both horizontal resolutions. Heavy and extreme precipitation events are projected to intensify across most of Europe throughout the whole year. All considered models agree on a distinct intensification of extremes by often more than +20% in winter and fall and over central and northern Europe. A reduction of rainy days and mean precipitation in summer is simulated by a large majority of models in the Mediterranean area, but intermodel spread between the simulations is large. In central Europe and France during summer, models project decreases in precipitation but more intense heavy and extreme rainfalls. Comparison to previous RCM projections from ENSEMBLES reveals consistency but slight differences in summer, where reductions in southern European precipitation are not as pronounced as previously projected. The projected changes of the European hydrological cycle may have substantial impact on environmental and anthropogenic systems. In particular, the simulations indicate a rising probability of summertime drought in southern Europe and more frequent and intense heavy rainfall across all of Europe.

  16. Final Report for "Community Petascale Project for Accelerator Science and Simulations"

    Energy Technology Data Exchange (ETDEWEB)

    Cary, J. R. [Tech-X Corporation, Boulder, CO (United States); Bruhwiler, D. L. [Tech-X Corporation, Boulder, CO (United States); Stoltz, P. H. [Tech-X Corporation, Boulder, CO (United States); Cormier-Michel, E. [Tech-X Corporation, Boulder, CO (United States); Cowan, B. [Tech-X Corporation, Boulder, CO (United States); Schwartz, B. T. [Tech-X Corporation, Boulder, CO (United States); Bell, G. [Tech-X Corporation, Boulder, CO (United States); Paul, K. [Tech-X Corporation, Boulder, CO (United States); Veitzer, S. [Tech-X Corporation, Boulder, CO (United States)

    2013-04-19

    This final report describes the work that has been accomplished over the past 5 years under the Community Petascale Project for Accelerator and Simulations (ComPASS) at Tech-X Corporation. Tech-X had been involved in the full range of ComPASS activities with simulation of laser plasma accelerator concepts, mainly in collaboration with LOASIS program at LBNL, simulation of coherent electron cooling in collaboration with BNL, modeling of electron clouds in high intensity accelerators, in collaboration with researchers at Fermilab and accurate modeling of superconducting RF cavity in collaboration with Fermilab, JLab and Cockcroft Institute in the UK.

  17. Retrieval process development and enhancements project Fiscal year 1995: Simulant development technology task progress report

    Energy Technology Data Exchange (ETDEWEB)

    Golcar, G.R.; Bontha, J.R.; Darab, J.G. [and others

    1997-01-01

    The mission of the Retrieval Process Development and Enhancements (RPD&E) project is to develop an understanding of retrieval processes, including emerging and existing technologies, gather data on these technologies, and relate the data to specific tank problems such that end-users have the requisite technical bases to make retrieval and closure decisions. The development of waste simulants is an integral part of this effort. The work of the RPD&E simulant-development task is described in this document. The key FY95 accomplishments of the RPD&E simulant-development task are summarized below.

  18. Aerodynamic Rear Cone for Trucks

    Science.gov (United States)

    Bullman, J.

    1985-01-01

    Wind-inflated cone reduces turbulence that ordinarily occurs in air just behind square-back truck traveling at high speed. Wind around truck would enter slits in folded cone and automatically deploy it. Energy lost to air turbulence greatly reduced, and fuel consumed by truck reduced accordingly. In addition, less air turbulence means less disturbance to nearby vehicles on highway.

  19. The Multiscale Systems Immunology project: software for cell-based immunological simulation

    Directory of Open Access Journals (Sweden)

    Kepler Thomas B

    2008-04-01

    Full Text Available Abstract Background Computer simulations are of increasing importance in modeling biological phenomena. Their purpose is to predict behavior and guide future experiments. The aim of this project is to model the early immune response to vaccination by an agent based immune response simulation that incorporates realistic biophysics and intracellular dynamics, and which is sufficiently flexible to accurately model the multi-scale nature and complexity of the immune system, while maintaining the high performance critical to scientific computing. Results The Multiscale Systems Immunology (MSI simulation framework is an object-oriented, modular simulation framework written in C++ and Python. The software implements a modular design that allows for flexible configuration of components and initialization of parameters, thus allowing simulations to be run that model processes occurring over different temporal and spatial scales. Conclusion MSI addresses the need for a flexible and high-performing agent based model of the immune system.

  20. project SENSE : multimodal simulation with full-body real-time verbal and nonverbal interactions

    NARCIS (Netherlands)

    Miri, Hossein; Kolkmeier, Jan; Taylor, Paul Jonathon; Poppe, Ronald; Heylen, Dirk; Poppe, Ronald; Meyer, John-Jules; Veltkamp, Remco; Dastani, Mehdi

    2016-01-01

    This paper presents a multimodal simulation system, project-SENSE, that combines virtual reality and full-body motion capture technologies with real-time verbal and nonverbal communication. We introduce the technical setup and employed hardware and software of a first prototype. We discuss the

  1. Final results of the supra project : Improved Simulation of Upset Recovery

    NARCIS (Netherlands)

    Fucke, L.; Groen, E.; Goman, M.; Abramov, N.; Wentink, M.; Nooij, S.; Zaichik, L.E.; Khrabrov, A.

    2012-01-01

    The objective of the European research project SUPRA (Simulation of Upset Recovery in Aviation) is to develop technologies that eventually contribute to a reduction of risk of Loss of control - in flight (LOC-I) accidents, today's major cause of fatal accidents in commercial aviation. To this end

  2. The Virtual Liver Project: Simulating Tissue Injury Through Molecular and Cellular Processes

    Science.gov (United States)

    Efficiently and humanely testing the safety of thousands of environmental chemicals is a challenge. The US EPA Virtual Liver Project (v-Liver™) is aimed at simulating the effects of environmental chemicals computationally in order to estimate the risk of toxic outcomes in humans...

  3. Numerical simulations of missile impacts on reinforced concrete plates: IRIS-2010/2012 benchmark project

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chulhun, E-mail: chchung5@dankook.ac.kr [Department of Civil and Environmental Engineering, Dankook University, 126 Jukjeon-dong, Yongin-si 448-701 (Korea, Republic of); Lee, Jungwhee, E-mail: jwhee2@dankook.ac.kr [Department of Civil and Environmental Engineering, Dankook University, 126 Jukjeon-dong, Yongin-si 448-701 (Korea, Republic of); Jung, Raeyoung, E-mail: k701jry@kins.re.kr [Korea Institute of Nuclear Safety, 62 Gwahak-ro, Yuseong-gu, Daejeon 305-600 (Korea, Republic of)

    2015-12-15

    Highlights: • The procedures and results performed during the IRIS-2010/2012 projects are described. • Numerical impact simulations were performed and the initial FE model was updated. • Loading function with a fictitious loading plate approach was suggested. • Three concrete models were used and the results were compared. - Abstract: This paper describes the procedures and results of the works done by the Korea Institute of Nuclear Safety (KINS) as a participant of the IRIS-2010 and 2012 benchmark projects, which have been organized by OECD/NEA IAGE working group. Within the scope of the IRIS-2012 project, uniaxial and tri-axial concrete tests were performed and the results were supplied. With these material test data, impact simulations of IRIS-2010 experiments (Punching P1 and Bending B1) were re-performed to improve the accuracy of the simulation results and to reduce the computation time. Numerical impact simulations were performed using an explicit dynamic code, LS-DYNA, and the initial FE model was updated through numerous parametric studies. Considering the symmetry of the structure, an updated model was constructed for ¼ of the structure, and the stiffness and mass of the supporting structure was considered. Loading function with a fictitious loading plate was applied instead of modeling projectiles to reduce the computation time. Three concrete models, Concrete damage rel. 3 (*MAT-072R3), Winfrith concrete (*MAT-084-085), and CSCM concrete (*MAT-159), were used for the impact simulations and the results were compared.

  4. Baseline process description for simulating plutonium oxide production for precalc project

    Energy Technology Data Exchange (ETDEWEB)

    Pike, J. A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-26

    Savannah River National Laboratory (SRNL) started a multi-year project, the PreCalc Project, to develop a computational simulation of a plutonium oxide (PuO2) production facility with the objective to study the fundamental relationships between morphological and physicochemical properties. This report provides a detailed baseline process description to be used by SRNL personnel and collaborators to facilitate the initial design and construction of the simulation. The PreCalc Project team selected the HB-Line Plutonium Finishing Facility as the basis for a nominal baseline process since the facility is operational and significant model validation data can be obtained. The process boundary as well as process and facility design details necessary for multi-scale, multi-physics models are provided.

  5. Toward the credibility of Northeast United States summer precipitation projections in CMIP5 and NARCCAP simulations

    Science.gov (United States)

    Thibeault, Jeanne M.; Seth, A.

    2015-10-01

    Precipitation projections for the northeast United States and nearby Canada (Northeast) are examined for 15 Fifth Phase of the Coupled Model Intercomparison Project (CMIP5) models. A process-based evaluation of atmospheric circulation features associated with wet Northeast summers is performed to examine whether credibility can be differentiated within the multimodel ensemble. Based on these evaluations, and an analysis of the interannual statistical properties of area-averaged precipitation, model subsets were formed. Multimodel precipitation projections from each subset were compared to the multimodel projection from all of the models. Higher-resolution North American Regional Climate Change Assessment Program (NARCCAP) regional climate models (RCMs) were subjected to a similar evaluation, grouping into subsets, and examination of future projections. CMIP5 models adequately simulate most large-scale circulation features associated with wet Northeast summers, though all have errors in simulating observed sea level pressure and moisture divergence anomalies in the western tropical Atlantic/Gulf of Mexico. Relevant large-scale processes simulated by the RCMs resemble those of their driving global climate models (GCMs), which are not always realistic. Future RCM studies could benefit from a process analysis of potential driving GCMs prior to dynamical downscaling. No CMIP5 or NARCCAP models were identified as clearly more credible, but six GCMs and four RCMs performed consistently better. Among the "Better" models, there is no consistency in the direction of future summer precipitation change. CMIP5 projections suggest that the Northeast precipitation response depends on the dynamics of the North Atlantic anticyclone and associated circulation and moisture convergence patterns, which vary among "Better" models. Even when model credibility cannot be clearly differentiated, examination of simulated processes provides important insights into their evolution under

  6. Comparisons of Simulated Hydrodynamics and Water Quality for Projected Demands in 2046, Pueblo Reservoir, Southeastern Colorado

    Science.gov (United States)

    Ortiz, Roderick F.; Galloway, Joel M.; Miller, Lisa D.; Mau, David P.

    2008-01-01

    Pueblo Reservoir is one of southeastern Colorado's most valuable water resources. The reservoir provides irrigation, municipal, and industrial water to various entities throughout the region. The reservoir also provides flood control, recreational activities, sport fishing, and wildlife enhancement to the region. The Bureau of Reclamation is working to meet its goal to issue a Final Environmental Impact Statement (EIS) on the Southern Delivery System project (SDS). SDS is a regional water-delivery project that has been proposed to provide a safe, reliable, and sustainable water supply through the foreseeable future (2046) for Colorado Springs, Fountain, Security, and Pueblo West. Discussions with the Bureau of Reclamation and the U.S. Geological Survey led to a cooperative agreement to simulate the hydrodynamics and water quality of Pueblo Reservoir. This work has been completed and described in a previously published report, U.S. Geological Survey Scientific Investigations Report 2008-5056. Additionally, there was a need to make comparisons of simulated hydrodynamics and water quality for projected demands associated with the various EIS alternatives and plans by Pueblo West to discharge treated water into the reservoir. Plans by Pueblo West are fully independent of the SDS project. This report compares simulated hydrodynamics and water quality for projected demands in Pueblo Reservoir resulting from changes in inflow and water quality entering the reservoir, and from changes to withdrawals from the reservoir as projected for the year 2046. Four of the seven EIS alternatives were selected for scenario simulations. The four U.S. Geological Survey simulation scenarios were the No Action scenario (EIS Alternative 1), the Downstream Diversion scenario (EIS Alternative 2), the Upstream Return-Flow scenario (EIS Alternative 4), and the Upstream Diversion scenario (EIS Alternative 7). Additionally, the results of an Existing Conditions scenario (water years 2000 through

  7. Risk management of a torrential flood construction project using the Monte Carlo simulation

    Directory of Open Access Journals (Sweden)

    Baumgertel Aleksandar

    2016-01-01

    Full Text Available Projects for the regulation of torrent basins carry various unforeseen adverse effects that may result in breached deadlines, increased costs, a reduction of quality etc. The paper presents the basic characteristics and most frequent risks associated with erosion control. Furthermore, it provides an overview of risk management through its basic stages - starting from risk identification and risk analysis to risk responses, including the methods used for risk analysis. As a part of quantitative methods for risk analysis, the Monte Carlo method is presented as the one most frequently used in simulations. The Monte Carlo method is a stochastic simulation method consisting of the following stages: the identification of criterion and relevant variables, the allocation of probability for relevant variables, the determination of correlation coefficient among relevant variables, simulation execution and result analysis. This method was applied in the analysis of the total cost of the project for the basin regulation of the Dumača River in order to determine the funding that would be used as a backup in case of unforeseen events with a negative impact. The project for the regulation of the Dumača River includes basin regulation in the form of complex flow profile and the lining of zones where necessary in terms of stability. The total cost is presented as a sum of costs of all works (preliminary works, earthworks, masonry works, concrete works and finishing works. The Monte Carlo simulation for cost analysis is carried out using the Oracle Crystal Ball software with its basic steps described in the paper. A sum of funding needed as a financial backup in case of unforeseen events with negative effects is obtained as the simulated total cost of the project.

  8. The accuracy of linear measurements of maxillary and mandibular edentulous sites in cone-beam computed tomography images with different fields of view and voxel sizes under simulated clinical conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ganguly, Rumpa; Ramesh, Aruna; Pagni, Sarah [Tufts University School of Dental Medicine, Boston (United States)

    2016-06-15

    The objective of this study was to investigate the effect of varying resolutions of cone-beam computed tomography images on the accuracy of linear measurements of edentulous areas in human cadaver heads. Intact cadaver heads were used to simulate a clinical situation. Fiduciary markers were placed in the edentulous areas of 4 intact embalmed cadaver heads. The heads were scanned with two different CBCT units using a large field of view (13 cm×16 cm) and small field of view (5 cm×8 cm) at varying voxel sizes (0.3 mm, 0.2 mm, and 0.16 mm). The ground truth was established with digital caliper measurements. The imaging measurements were then compared with caliper measurements to determine accuracy. The Wilcoxon signed rank test revealed no statistically significant difference between the medians of the physical measurements obtained with calipers and the medians of the CBCT measurements. A comparison of accuracy among the different imaging protocols revealed no significant differences as determined by the Friedman test. The intraclass correlation coefficient was 0.961, indicating excellent reproducibility. Inter-observer variability was determined graphically with a Bland-Altman plot and by calculating the intraclass correlation coefficient. The Bland-Altman plot indicated very good reproducibility for smaller measurements but larger discrepancies with larger measurements. The CBCT-based linear measurements in the edentulous sites using different voxel sizes and FOVs are accurate compared with the direct caliper measurements of these sites. Higher resolution CBCT images with smaller voxel size did not result in greater accuracy of the linear measurements.

  9. The SIMRAND methodology: Theory and application for the simulation of research and development projects

    Science.gov (United States)

    Miles, R. F., Jr.

    1986-01-01

    A research and development (R&D) project often involves a number of decisions that must be made concerning which subset of systems or tasks are to be undertaken to achieve the goal of the R&D project. To help in this decision making, SIMRAND (SIMulation of Research ANd Development Projects) is a methodology for the selection of the optimal subset of systems or tasks to be undertaken on an R&D project. Using alternative networks, the SIMRAND methodology models the alternative subsets of systems or tasks under consideration. Each path through an alternative network represents one way of satisfying the project goals. Equations are developed that relate the system or task variables to the measure of reference. Uncertainty is incorporated by treating the variables of the equations probabilistically as random variables, with cumulative distribution functions assessed by technical experts. Analytical techniques of probability theory are used to reduce the complexity of the alternative networks. Cardinal utility functions over the measure of preference are assessed for the decision makers. A run of the SIMRAND Computer I Program combines, in a Monte Carlo simulation model, the network structure, the equations, the cumulative distribution functions, and the utility functions.

  10. Cone and Seed Maturation of Southern Pines

    Science.gov (United States)

    James P. Barnett

    1976-01-01

    If slightly reduced yields and viability are acceptable, loblolly and slash cone collections can begin 2 to 3 weeks before maturity if the cones are stored before processing. Longleaf(P. palestris Mill.) pine cones should be collected only when mature, as storage decreased germination of seeds from immature cones. Biochemical analyses to determine reducing sugar...

  11. Cosmic rays Monte Carlo simulations for the Extreme Energy Events Project

    CERN Document Server

    Abbrescia, M; Aiola, S; Antolini, R; Avanzini, C; Baldini Ferroli, R; Bencivenni, G; Bossini, E; Bressan, E; Chiavassa, A; Cicalò, C; Cifarelli, L; Coccia, E; De Gruttola, D; De Pasquale, S; Di Giovanni, A; D'Incecco, M; Dreucci, M; Fabbri, F L; Frolov, V; Garbini, M; Gemme, G; Gnesi, I; Gustavino, C; Hatzifotiadou, D; La Rocca, P; Li, S; Librizzi, F; Maggiora, A; Massai, M; Miozzi, S; Panareo, M; Paoletti, R; Perasso, L; Pilo, F; Piragino, G; Regano, A; Riggi, F; Righini, G C; Sartorelli, G; Scapparone, E; Scribano, A; Selvi, M; Serci, S; Siddi, E; Spandre, G; Squarcia, S; Taiuti, M; Tosello, F; Votano, L; Williams, M C S; Yánez, G; Zichichi, A; Zuyeuski, R

    2014-01-01

    The Extreme Energy Events Project (EEE Project) is an innovative experiment to study very high energy cosmic rays by means of the detection of the associated air shower muon component. It consists of a network of tracking detectors installed inside Italian High Schools. Each tracking detector, called EEE telescope, is composed of three Multigap Resistive Plate Chambers (MRPCs). At present, 43 telescopes are installed and taking data, opening the way for the detection of far away coincidences over a total area of about 3 × 10 5 km 2 . In this paper we present the Monte Carlo simulations that have been performed to predict the expected coincidence rate between distant EEE telescopes.

  12. 3D numerical simulation of projection welding of square nuts to sheets

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Zhang, W.; Martins, P. A. F.

    2015-01-01

    formulation inorder to model the frictional sliding between the square nut projections and the sheets during the weld-ing process. It is proved that the implementation of friction increases the accuracy of the simulations,and the dynamic influence of friction on the process is explained.© 2014 Elsevier B......The challenge of developing a three-dimensional finite element computer program for electro-thermo-mechanical industrial modeling of resistance welding is presented, and the program is applied to thesimulation of projection welding of square nuts to sheets. Results are compared with experimental...

  13. Beam dynamics simulations and measurements at the Project X Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Gianfelice-Wendt, E.; Scarpine, V.E.; Webber, R.C.; /Fermilab

    2011-03-01

    Project X, under study at Fermilab, is a multitask high-power superconducting RF proton beam facility, aiming to provide high intensity protons for rare processes experiments and nuclear physics at low energy, and simultaneously for the production of neutrinos, as well as muon beams in the long term. A beam test facility - former known as High Intensity Neutrino Source (HINS) - is under commissioning for testing critical components of the project, e.g. dynamics and diagnostics at low beam energies, broadband beam chopping, RF power generation and distribution. In this paper we describe the layout of the test facility and present beam dynamics simulations and measurements.

  14. Final Project Report: Data Locality Enhancement of Dynamic Simulations for Exascale Computing

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Xipeng [North Carolina State Univ., Raleigh, NC (United States)

    2016-04-27

    The goal of this project is to develop a set of techniques and software tools to enhance the matching between memory accesses in dynamic simulations and the prominent features of modern and future manycore systems, alleviating the memory performance issues for exascale computing. In the first three years, the PI and his group have achieves some significant progress towards the goal, producing a set of novel techniques for improving the memory performance and data locality in manycore systems, yielding 18 conference and workshop papers and 4 journal papers and graduating 6 Ph.Ds. This report summarizes the research results of this project through that period.

  15. Evolution and experience with the ATLAS Simulation at Point1 Project

    CERN Document Server

    Ballestrero, Sergio; The ATLAS collaboration

    2017-01-01

    The Simulation at Point1 project is successfully running traditional ATLAS simulation jobs on the TDAQ HLT resources. The pool of available resources changes dynamically, therefore we need to be very effective in exploiting the available computing cycles. We present our experience with using the Event Service that provides the event-level granularity of computations. We show the design decisions and overhead time related to the usage of the Event Service. The improved utilisation of the resources is also presented with the recent development in monitoring, automatic alerting, deployment and GUI.

  16. Integrated Vehicle Health Management Project-Modeling and Simulation for Wireless Sensor Applications

    Science.gov (United States)

    Wallett, Thomas M.; Mueller, Carl H.; Griner, James H., Jr.

    2009-01-01

    This paper describes the efforts in modeling and simulating electromagnetic transmission and reception as in a wireless sensor network through a realistic wing model for the Integrated Vehicle Health Management project at the Glenn Research Center. A computer model in a standard format for an S-3 Viking aircraft was obtained, converted to a Microwave Studio software format, and scaled to proper dimensions in Microwave Studio. The left wing portion of the model was used with two antenna models, one transmitting and one receiving, to simulate radio frequency transmission through the wing. Transmission and reception results were inconclusive.

  17. Evolution and experience with the ATLAS simulation at Point1 project

    CERN Document Server

    Ballestrero, Sergio; The ATLAS collaboration; Fazio, Daniel; Di Girolamo, Alessandro; Kouba, Tomas; Lee, Christopher; Scannicchio, Diana; Schovancova, Jaroslava; Twomey, Matthew Shaun; Wang, Fuquan; Zaytsev, Alexander

    2016-01-01

    The Simulation at Point1 project is successfully running traditional ATLAS simulation jobs on the TDAQ HLT resources. The pool of available resources changes dynamically, therefore we need to be very effective in exploiting the available computing cycles. We will present our experience with using the Event Service that provides the event-level granularity of computations. We will show the design decisions and overhead time related to the usage of the Event Service. The improved utilization of the resources will also be presented with the recent development in monitoring, automatic alerting, deployment and GUI.

  18. Simulated bat populations erode when exposed to climate change projections for western North America.

    Directory of Open Access Journals (Sweden)

    Mark A Hayes

    Full Text Available Recent research has demonstrated that temperature and precipitation conditions correlate with successful reproduction in some insectivorous bat species that live in arid and semiarid regions, and that hot and dry conditions correlate with reduced lactation and reproductive output by females of some species. However, the potential long-term impacts of climate-induced reproductive declines on bat populations in western North America are not well understood. We combined results from long-term field monitoring and experiments in our study area with information on vital rates to develop stochastic age-structured population dynamics models and analyzed how simulated fringed myotis (Myotis thysanodes populations changed under projected future climate conditions in our study area near Boulder, Colorado (Boulder Models and throughout western North America (General Models. Each simulation consisted of an initial population of 2,000 females and an approximately stable age distribution at the beginning of the simulation. We allowed each population to be influenced by the mean annual temperature and annual precipitation for our study area and a generalized range-wide model projected through year 2086, for each of four carbon emission scenarios (representative concentration pathways RCP2.6, RCP4.5, RCP6.0, RCP8.5. Each population simulation was repeated 10,000 times. Of the 8 Boulder Model simulations, 1 increased (+29.10%, 3 stayed approximately stable (+2.45%, +0.05%, -0.03%, and 4 simulations decreased substantially (-44.10%, -44.70%, -44.95%, -78.85%. All General Model simulations for western North America decreased by >90% (-93.75%, -96.70%, -96.70%, -98.75%. These results suggest that a changing climate in western North America has the potential to quickly erode some forest bat populations including species of conservation concern, such as fringed myotis.

  19. Dirac fermions on graphite cones

    CERN Document Server

    Osipov, V A

    2001-01-01

    The electronic structure of graphitic cones is investigated within the self-consistent field-theory model. The local and total density of states near the apex is found for cones of different opening angles. For extended electronic states, total density of states is found to vanish at the Fermi level at any opening angles more than 60 deg. In turn, for power-law localized states, normalized zero-energy modes are shown to emerge

  20. A Model-Based Scatter Artifacts Correction for Cone Beam CT

    CERN Document Server

    Zhao, Wei; Zhu, Jun; Wang, Luyao; Xing, Lei

    2016-01-01

    The purpose of this work is to provide a fast and accurate scatter artifacts correction algorithm for cone beam CT (CBCT) imaging. The method starts with an estimation of coarse scatter profiles for a set of CBCT data in either image domain or projection domain. A denoising algorithm designed specifically for Poisson signals is then applied to derive the final scatter distribution. Qualitative and quantitative evaluations using thorax and abdomen phantoms with Monte Carlo (MC) simulations, experimental Catphan phantom data, and in vivo human data acquired for a clinical image guided radiation therapy were performed. Results show that the proposed algorithm can significantly reduce scatter artifacts and recover the correct HU in either projection domain or image domain. For the MC thorax phantom study, four components segmentation yield the best results, while the results of three components segmentation are still acceptable. For the Catphan phantom data, the mean value over all pixels in the residual image is...

  1. High-resolution global climate modelling: the UPSCALE project, a large-simulation campaign

    Directory of Open Access Journals (Sweden)

    M. S. Mizielinski

    2014-08-01

    Full Text Available The UPSCALE (UK on PRACE: weather-resolving Simulations of Climate for globAL Environmental risk project constructed and ran an ensemble of HadGEM3 (Hadley Centre Global Environment Model 3 atmosphere-only global climate simulations over the period 1985–2011, at resolutions of N512 (25 km, N216 (60 km and N96 (130 km as used in current global weather forecasting, seasonal prediction and climate modelling respectively. Alongside these present climate simulations a parallel ensemble looking at extremes of future climate was run, using a time-slice methodology to consider conditions at the end of this century. These simulations were primarily performed using a 144 million core hour, single year grant of computing time from PRACE (the Partnership for Advanced Computing in Europe in 2012, with additional resources supplied by the Natural Environment Research Council (NERC and the Met Office. Almost 400 terabytes of simulation data were generated on the HERMIT supercomputer at the High Performance Computing Center Stuttgart (HLRS, and transferred to the JASMIN super-data cluster provided by the Science and Technology Facilities Council Centre for Data Archival (STFC CEDA for analysis and storage. In this paper we describe the implementation of the project, present the technical challenges in terms of optimisation, data output, transfer and storage that such a project involves and include details of the model configuration and the composition of the UPSCALE data set. This data set is available for scientific analysis to allow assessment of the value of model resolution in both present and potential future climate conditions.

  2. An optimization-based method for geometrical calibration in cone-beam CT without dedicated phantoms.

    Science.gov (United States)

    Panetta, D; Belcari, N; Del Guerra, A; Moehrs, S

    2008-07-21

    In this paper we present a new method for the determination of geometrical misalignments in cone-beam CT scanners, from the analysis of the projection data of a generic object. No a priori knowledge of the object shape and positioning is required. We show that a cost function, which depends on the misalignment parameters, can be defined using the projection data and that such a cost function has a local minimum in correspondence to the actual parameters of the system. Hence, the calibration of the scanner can be carried out by minimizing the cost function using standard optimization techniques. The method is developed for a particular class of 3D object functions, for which the redundancy of the fan beam sinogram in the transaxial midplane can be extended to cone-beam projection data, even at wide cone angles. The method has an approximated validity for objects which do not belong to that class; in that case, a suitable subset of the projection data can be selected in order to compute the cost function. We show by numerical simulations that our method is capable to determine with high accuracy the most critical misalignment parameters of the scanner, i.e., the transversal shift and the skew of the detector. Additionally, the detector slant can be determined. Other parameters such as the detector tilt, the longitudinal shift and the error in the source-detector distance cannot be determined with our method, as the proposed cost function has a very weak dependence on them. However, due to the negligible influence of these latter parameters in the reconstructed image quality, they can be kept fixed at estimated values in both calibration and reconstruction processes without compromising the final result. A trade-off between computational cost and calibration accuracy must be considered when choosing the data subset used for the computation of the cost function. Results on real data of a mouse femur as obtained with a small animal micro-CT are shown as well, proving

  3. An optimization-based method for geometrical calibration in cone-beam CT without dedicated phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Panetta, D; Belcari, N; Guerra, A Del; Moehrs, S [Department of Physics ' E. Fermi' , University of Pisa, L.go B. Pontecorvo, 3-I-56127 Pisa (Italy)], E-mail: daniele.panetta@pi.infn.it

    2008-07-21

    In this paper we present a new method for the determination of geometrical misalignments in cone-beam CT scanners, from the analysis of the projection data of a generic object. No a priori knowledge of the object shape and positioning is required. We show that a cost function, which depends on the misalignment parameters, can be defined using the projection data and that such a cost function has a local minimum in correspondence to the actual parameters of the system. Hence, the calibration of the scanner can be carried out by minimizing the cost function using standard optimization techniques. The method is developed for a particular class of 3D object functions, for which the redundancy of the fan beam sinogram in the transaxial midplane can be extended to cone-beam projection data, even at wide cone angles. The method has an approximated validity for objects which do not belong to that class; in that case, a suitable subset of the projection data can be selected in order to compute the cost function. We show by numerical simulations that our method is capable to determine with high accuracy the most critical misalignment parameters of the scanner, i.e., the transversal shift and the skew of the detector. Additionally, the detector slant can be determined. Other parameters such as the detector tilt, the longitudinal shift and the error in the source-detector distance cannot be determined with our method, as the proposed cost function has a very weak dependence on them. However, due to the negligible influence of these latter parameters in the reconstructed image quality, they can be kept fixed at estimated values in both calibration and reconstruction processes without compromising the final result. A trade-off between computational cost and calibration accuracy must be considered when choosing the data subset used for the computation of the cost function. Results on real data of a mouse femur as obtained with a small animal micro-CT are shown as well, proving

  4. A realistic projection simulator for laboratory based X-ray micro-CT

    Energy Technology Data Exchange (ETDEWEB)

    Dhaene, Jelle, E-mail: jelle.dhaene@ugent.be; Pauwels, Elin, E-mail: elin.pauwels@ugent.be; De Schryver, Thomas; De Muynck, Amelie; Dierick, Manuel; Van Hoorebeke, Luc

    2015-01-01

    In X-ray computed tomography (CT) each voxel of the reconstructed image contains a calculated grey value which represents the linear attenuation coefficient for the materials in that voxel. Conventional laboratory based CT scanners use polychromatic X-ray sources and integrating detectors with an energy dependent efficiency. Consequently the reconstructed attenuation coefficients will depend on the spectrum of the source and the spectral sensitivity of the detector. Beam hardening will alter the spectrum significantly as the beam propagates through the sample. Therefore, sample composition and shape will affect the reconstructed attenuation coefficients as well. A polychromatic projection simulator has been developed at the “Centre for X-ray Tomography” of the Ghent University (UGCT) which takes into account the aforementioned variables, allowing for complete and realistic simulations of CT scans for a wide range of geometrical setups. Monte Carlo simulations of the X-ray tubes and detectors were performed to model their spectral behaviour. In this paper, the implementation and features of the program are discussed. Simulated and real CT scans are compared to demonstrate the quantitative correctness of the simulations. Experiments performed at two different UGCT scanners yield a maximum deviation of 3.9% and 6.5% respectively, between the measured and simulated reconstructed attenuation coefficients.

  5. A simulation study on the focal plane detector of the LAUE project

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, M., E-mail: mkhalil@in2p3.fr [APC Laboratory, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France); Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44100 Ferrara (Italy); Frontera, F. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44100 Ferrara (Italy); INAF/IASF-Bologna, Via P. Gobetti 101, Bologna (Italy); Caroli, E. [INAF/IASF-Bologna, Via P. Gobetti 101, Bologna (Italy); Virgilli, E.; Valsan, V. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44100 Ferrara (Italy)

    2015-06-21

    The LAUE project, supported by the Italian Space Agency (ASI), is devoted to the development of a long focal length (even 20 m or longer) Laue lens for gamma ray astronomy between 80 and 600 keV. These lenses take advantage of Bragg diffraction to focus radiation onto a small spot drastically improving the signal to noise ratio as well as reducing the required size of the detector significantly. In this paper we present a Monte-Carlo simulation study with MEGALIB to optimize, for space applications, the detector size to achieve high detection efficiency, and to optimize the position resolution of the detector to reconstruct the Point Spread Function of the lens considered for the LAUE project. Then we will show simulations, using the SILVACO semiconductor simulation toolkit, on the optimized detector to estimate its capacitance per channel and depletion voltage. In all of the simulations, two materials were compared; a low density material (Silicon) and a high density material (Germanium). - Highlights: • The quantized Hall plateaus and Shubnikov de Haas oscillations in transition metal doped topological insulators are observed. • The evidence of a two-dimensional/layered transport of the bulk electrons is reported. • An obvious ferromagnetism in doped topological insulators is observed. • Care should be taken to pindown the transport of the topological SS in topological insulators.

  6. DECISION-MAKING IN THE IMPLEMENTATION OF IT-PROJECTS THROUGH SIMULATION

    Directory of Open Access Journals (Sweden)

    Константин Викторович КОШКИН

    2016-02-01

    Full Text Available The article analyzes the key success factors of IT-projects, which can be influenced. A key factor is the "optimization". Because of the complexity and non-linear dependence between the indicators, the use of any optimization models is not possible. In practice, the analysis is generally limited to a small number of key scenarios. Automation of the process is possible by means of optimization experiments based simulation. The work for this project proposed simulation model IT-companies, based on the principles of integration of system dynamics and cognitive modeling. Shown examples of experiments with model: simulation, optimization of the experiment, an experiment on the Monte Carlo method. Changes in parameter values when making the various administrative decisions has been analyzed. To perform scenario analysis for the input variables are determined by parameters that define their targets. With the help of optimization experiments, it is possible to find the values of model parameters under which the simulation results most closely match the specified data. The ways to adapt the input to achieve predictable results has been proposed.

  7. Final report on LDRD project: Simulation/optimization tools for system variability analysis

    Energy Technology Data Exchange (ETDEWEB)

    R. L. Bierbaum; R. F. Billau; J. E. Campbell; K. D. Marx; R. J. Sikorski; B. M. Thompson; S. D. Wix

    1999-10-01

    >This work was conducted during FY98 (Proposal Number 98-0036) and FY99 (Proposal Number 99-0818) under the auspices of the Sandia National Laboratories Laboratory-Directed Research and Development (LDRD) program. Electrical simulation typically treats a single data point in the very large input space of component properties. For electrical simulation to reach its full potential as a design tool, it must be able to address the unavoidable variability and uncertainty in component properties. Component viability is strongly related to the design margin (and reliability) of the end product. During the course of this project, both tools and methodologies were developed to enable analysis of variability in the context of electrical simulation tools. Two avenues to link relevant tools were also developed, and the resultant toolset was applied to a major component.

  8. Growth Cone Travel in Space and Time: the Cellular Ensemble of Cytoskeleton, Adhesion, and Membrane

    National Research Council Canada - National Science Library

    Vitriol, Eric A; Zheng, James Q

    2012-01-01

    Growth cones, found at the tip of axonal projections, are the sensory and motile organelles of developing neurons that enable axon pathfinding and target recognition for precise wiring of the neural circuitry...

  9. Improved correlation between Texas cone penetrometer blow count and undrained shear strength of soft clays.

    Science.gov (United States)

    2009-01-01

    The objective of this project was to develop an improved correlation between Texas Cone Penetrometer (TCP) : blow count and undrained shear strength for soft, clay soils in the upper approximately 30 feet of the ground. Subsurface : explorations were...

  10. Region-of-interest reconstruction for a cone-beam dental CT with a circular trajectory

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Zhanli, E-mail: huzhanli1983@gmail.com [Paul C. Lauterbur Research Center For Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Zou, Jing; Gui, Jianbao; Zheng, Hairong [Paul C. Lauterbur Research Center For Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Xia, Dan, E-mail: dan.xia@siat.ac.cn [Paul C. Lauterbur Research Center For Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China)

    2013-04-21

    Dental CT is the most appropriate and accurate device for preoperative evaluation of dental implantation. It can demonstrate the quantity of bone in three dimensions (3D), the location of important adjacent anatomic structures and the quality of available bone with minimal geometric distortion. Nevertheless, with the rapid increase of dental CT examinations, we are facing the problem of dose reduction without loss of image quality. In this work, backprojection-filtration (BPF) and Feldkamp–Davis–Kress (FDK) algorithm was applied to reconstruct the 3D full image and region-of-interest (ROI) image from complete and truncated circular cone-beam data respectively by computer-simulation. In addition, the BPF algorithm was evaluated based on the 3D ROI-image reconstruction from real data, which was acquired from our developed circular cone-beam prototype dental CT system. The results demonstrated that the ROI-image quality reconstructed from truncated data using the BPF algorithm was comparable to that reconstructed from complete data. The FDK algorithm, however, created artifacts while reconstructing ROI-image. Thus it can be seen, for circular cone-beam dental CT, reducing scanning angular range of the BPF algorithm used for ROI-image reconstruction are helpful for reducing the radiation dose and scanning time. Finally, an analytical method was developed for estimation of the ROI projection area on the detector before CT scanning, which would help doctors to roughly estimate the total radiation dose before the CT examination. -- Highlights: ► BPF algorithm was applied by using dental CT for the first time. ► A method was developed for estimation of projection region before CT scanning. ► Roughly predict the total radiation dose before CT scans. ► Potential reduce imaging radiation dose, scatter, and scanning time.

  11. GPU-accelerated regularized iterative reconstruction for few-view cone beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Matenine, Dmitri, E-mail: dmitri.matenine.1@ulaval.ca [Département de physique, de génie physique et d’optique, Université Laval, Québec, Québec G1V 0A6 (Canada); Goussard, Yves, E-mail: yves.goussard@polymtl.ca [Département de génie électrique/Institut de génie biomédical, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, Québec H3C 3A7 (Canada); Després, Philippe, E-mail: philippe.despres@phy.ulaval.ca [Département de physique, de génie physique et d’optique and Centre de recherche sur le cancer, Université Laval, Québec, Québec G1V 0A6 (Canada)

    2015-04-15

    Purpose: The present work proposes an iterative reconstruction technique designed for x-ray transmission computed tomography (CT). The main objective is to provide a model-based solution to the cone-beam CT reconstruction problem, yielding accurate low-dose images via few-views acquisitions in clinically acceptable time frames. Methods: The proposed technique combines a modified ordered subsets convex (OSC) algorithm and the total variation minimization (TV) regularization technique and is called OSC-TV. The number of subsets of each OSC iteration follows a reduction pattern in order to ensure the best performance of the regularization method. Considering the high computational cost of the algorithm, it is implemented on a graphics processing unit, using parallelization to accelerate computations. Results: The reconstructions were performed on computer-simulated as well as human pelvic cone-beam CT projection data and image quality was assessed. In terms of convergence and image quality, OSC-TV performs well in reconstruction of low-dose cone-beam CT data obtained via a few-view acquisition protocol. It compares favorably to the few-view TV-regularized projections onto convex sets (POCS-TV) algorithm. It also appears to be a viable alternative to full-dataset filtered backprojection. Execution times are of 1–2 min and are compatible with the typical clinical workflow for nonreal-time applications. Conclusions: Considering the image quality and execution times, this method may be useful for reconstruction of low-dose clinical acquisitions. It may be of particular benefit to patients who undergo multiple acquisitions by reducing the overall imaging radiation dose and associated risks.

  12. Simulation studies for a high resolution time projection chamber at the international linear collider

    Energy Technology Data Exchange (ETDEWEB)

    Muennich, A.

    2007-03-26

    The International Linear Collider (ILC) is planned to be the next large accelerator. The ILC will be able to perform high precision measurements only possible at the clean environment of electron positron collisions. In order to reach this high accuracy, the requirements for the detector performance are challenging. Several detector concepts are currently under study. The understanding of the detector and its performance will be crucial to extract the desired physics results from the data. To optimise the detector design, simulation studies are needed. Simulation packages like GEANT4 allow to model the detector geometry and simulate the energy deposit in the different materials. However, the detector response taking into account the transportation of the produced charge to the readout devices and the effects ofthe readout electronics cannot be described in detail. These processes in the detector will change the measured position of the energy deposit relative to the point of origin. The determination of this detector response is the task of detailed simulation studies, which have to be carried out for each subdetector. A high resolution Time Projection Chamber (TPC) with gas amplification based on micro pattern gas detectors, is one of the options for the main tracking system at the ILC. In the present thesis a detailed simulation tool to study the performance of a TPC was developed. Its goal is to find the optimal settings to reach an excellent momentum and spatial resolution. After an introduction to the present status of particle physics and the ILC project with special focus on the TPC as central tracker, the simulation framework is presented. The basic simulation methods and implemented processes are introduced. Within this stand-alone simulation framework each electron produced by primary ionisation is transferred through the gas volume and amplified using Gas Electron Multipliers (GEMs). The output format of the simulation is identical to the raw data from a

  13. PROJECTED PRECIPITATION CHANGES IN CENTRAL/EASTERN EUROPE ON THE BASIS OF ENSEMBLE SIMULATIONS

    Directory of Open Access Journals (Sweden)

    Erika Miklos

    2012-03-01

    Full Text Available Projected precipitation changes in Central/Eastern Europe on the basis of ENSEMBLE simulations. For building appropriate local/national adaptation and mitigation strategies, detailed analysis of regional climate change is essential. In order to estimate the climate change for the 21st century, both global and regional models may be used. However, due to the coarse horizontal resolution, global climate models are not appropriate to describe regional scale climate processes. On the other hand, regional climate models (RCMs provide more realistic regional climate scenarios. A wide range of RCM experiments was accomplished in the frame of the ENSEMBLES project funded by the EU FP6 program, which was one of the largest climate change research project ever completed. All the RCM experiments used 25 km horizontal resolution and the A1B emission scenario, according to which CO2 concentration by 2100 is estimated to exceed 700 ppm, i.e., more than twice of the preindustrial level.The 25 km spatial resolution is fine enough to estimate the future hydrology-related conditions in different parts of Europe, from which we separated and analyzed simulated climate data sets for the Central/Eastern European region. Precipitation is an especially important climatological variable because of agricultural aspects and flood-related natural hazards, which may seriously affect all the countries in the evaluated region. On the basis of our results, different RCM simulations generally project drier summers and wetter winters (compared to the recent decades. The southern countries are more likely to suffer more intense warming, especially, in summer, and also, more intense drought events due to the stronger Mediterranean impact.

  14. Cloud radiative effects and changes simulated by the Coupled Model Intercomparison Project Phase 5 models

    Science.gov (United States)

    Shin, Sun-Hee; Kim, Ok-Yeon; Kim, Dongmin; Lee, Myong-In

    2017-07-01

    Using 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects (CREs) in the historical run driven by observed external radiative forcing for 1850-2005, and their future changes in the RCP (Representative Concentration Pathway) 4.5 scenario runs for 2006-2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics, four models—ACCESS1.0, ACCESS1.3, HadGEM2-CC, and HadGEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average. All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about -0.99% K-1 and net radiative warming of 0.46 W m-2 K-1, suggesting a role of positive feedback to global warming.

  15. An ice-cream cone model for coronal mass ejections

    Science.gov (United States)

    Xue, X. H.; Wang, C. B.; Dou, X. K.

    2005-08-01

    In this study, we use an ice-cream cone model to analyze the geometrical and kinematical properties of the coronal mass ejections (CMEs). Assuming that in the early phase CMEs propagate with near-constant speed and angular width, some useful properties of CMEs, namely the radial speed (v), the angular width (α), and the location at the heliosphere, can be obtained considering the geometrical shapes of a CME as an ice-cream cone. This model is improved by (1) using an ice-cream cone to show the near real configuration of a CME, (2) determining the radial speed via fitting the projected speeds calculated from the height-time relation in different azimuthal angles, (3) not only applying to halo CMEs but also applying to nonhalo CMEs.

  16. Generalized Fourier slice theorem for cone-beam image reconstruction.

    Science.gov (United States)

    Zhao, Shuang-Ren; Jiang, Dazong; Yang, Kevin; Yang, Kang

    2015-01-01

    The cone-beam reconstruction theory has been proposed by Kirillov in 1961, Tuy in 1983, Feldkamp in 1984, Smith in 1985, Pierre Grangeat in 1990. The Fourier slice theorem is proposed by Bracewell 1956, which leads to the Fourier image reconstruction method for parallel-beam geometry. The Fourier slice theorem is extended to fan-beam geometry by Zhao in 1993 and 1995. By combining the above mentioned cone-beam image reconstruction theory and the above mentioned Fourier slice theory of fan-beam geometry, the Fourier slice theorem in cone-beam geometry is proposed by Zhao 1995 in short conference publication. This article offers the details of the derivation and implementation of this Fourier slice theorem for cone-beam geometry. Especially the problem of the reconstruction from Fourier domain has been overcome, which is that the value of in the origin of Fourier space is 0/0. The 0/0 type of limit is proper handled. As examples, the implementation results for the single circle and two perpendicular circle source orbits are shown. In the cone-beam reconstruction if a interpolation process is considered, the number of the calculations for the generalized Fourier slice theorem algorithm is O(N^4), which is close to the filtered back-projection method, here N is the image size of 1-dimension. However the interpolation process can be avoid, in that case the number of the calculations is O(N5).

  17. Simulations of Aperture Synthesis Imaging Radar for the EISCAT_3D Project

    Science.gov (United States)

    La Hoz, C.; Belyey, V.

    2012-12-01

    EISCAT_3D is a project to build the next generation of incoherent scatter radars endowed with multiple 3-dimensional capabilities that will replace the current EISCAT radars in Northern Scandinavia. Aperture Synthesis Imaging Radar (ASIR) is one of the technologies adopted by the EISCAT_3D project to endow it with imaging capabilities in 3-dimensions that includes sub-beam resolution. Complemented by pulse compression, it will provide 3-dimensional images of certain types of incoherent scatter radar targets resolved to about 100 metres at 100 km range, depending on the signal-to-noise ratio. This ability will open new research opportunities to map small structures associated with non-homogeneous, unstable processes such as aurora, summer and winter polar radar echoes (PMSE and PMWE), Natural Enhanced Ion Acoustic Lines (NEIALs), structures excited by HF ionospheric heating, meteors, space debris, and others. To demonstrate the feasibility of the antenna configurations and the imaging inversion algorithms a simulation of synthetic incoherent scattering data has been performed. The simulation algorithm incorporates the ability to control the background plasma parameters with non-homogeneous, non-stationary components over an extended 3-dimensional space. Control over the positions of a number of separated receiving antennas, their signal-to-noise-ratios and arriving phases allows realistic simulation of a multi-baseline interferometric imaging radar system. The resulting simulated data is fed into various inversion algorithms. This simulation package is a powerful tool to evaluate various antenna configurations and inversion algorithms. Results applied to realistic design alternatives of EISCAT_3D will be described.

  18. SU-F-J-40: Evaluation of Sensitivity of the Automatic Matching Between Cone-Beam CT Image and Simulation CT Image in TrueBeam 2.0 Imaging System 6DoF Considering Different Uncertainty Sources

    Energy Technology Data Exchange (ETDEWEB)

    Bonaque, J; Bautista-Ballesteros, J; Ibanez-Rosello, B; Lliso, F; Carmona, V; Gimeno, J [Hospital La Fe, Valencia, Valencia (Spain); Perez-Calatayud, J [Hospital La Fe, Valencia, Valencia (Spain); Clinica Benidorm, Benidorm, Alicante (Spain)

    2016-06-15

    Purpose: To estimate the sensitivity of TrueBeam 2.0 Imaging System 6DoF automatic matching tool through the acquisition of cone-beam CT images in different phantoms applying submillimeter translations and rotations of tenths of a degree and registered with image simulation CT. Methods: To evaluate overall system-wide image, we consider two uncertainties source; First, the uncertainty of the manual phantom displacement (ε-m). This uncertainty is calculated by a digital caliper (0.01 mm) for vertical (Vrt), lateral (Lat) and longitudinal (Lng). A digital inclinometer (0.01°) for the pitch and roll and the own phantom scale to evaluate the coordinate rotation (Rtn). The second uncertainty is the displacement detected by the algorithm system of matching (σ-d) that we obtain from the standard deviations of the different measurements. We use three different phantoms. The BrainLab Radiosurgery system for supporting masks with an anthropomorphic dummy adapted to allow displacements of 0.1 mm in Vrt, Lat and Lng dimensions and rotations of 0.1° in Pitch dimension. For the analysis of the Rtn and Roll dimensions we use two homemade phantoms (RinoRot and RinoRoll, La Fe Hospital, Valencia, Spain) that allow rotations of 0.3°. Results: In the case of manual displacement of 0.10 ± 0.03 mm in the translations, the system detect 0.10 ± 0.07 mm, 0.12 ± 0.07 mm and 0.13 ± 0.07 mm (mean ± SD) in Lat, Vrt and Lng respectively. In the case of rotational dimension, manual displacement of 0.3 ± 0.1° was detected with 0.19 ± 0.06°, 0.29 ± 0.03° and 0.27 ± 0.06° in Pitch, Roll and Rtn. Conclusion: We conclude that the sensitivity of the automatic matching system is within 0.10 mm in translations and 0.3° in rotations. These values are under the own sensitivity of the software.

  19. The Geoengineering Model Intercomparison Project Phase 6 (GeoMIP6: simulation design and preliminary results

    Directory of Open Access Journals (Sweden)

    B. Kravitz

    2015-10-01

    Full Text Available We present a suite of new climate model experiment designs for the Geoengineering Model Intercomparison Project (GeoMIP. This set of experiments, named GeoMIP6 (to be consistent with the Coupled Model Intercomparison Project Phase 6, builds on the previous GeoMIP project simulations, and has been expanded to address several further important topics, including key uncertainties in extreme events, the use of geoengineering as part of a portfolio of responses to climate change, and the relatively new idea of cirrus cloud thinning to allow more longwave radiation to escape to space. We discuss experiment designs, as well as the rationale for those designs, showing preliminary results from individual models when available. We also introduce a new feature, called the GeoMIP Testbed, which provides a platform for simulations that will be performed with a few models and subsequently assessed to determine whether the proposed experiment designs will be adopted as core (Tier 1 GeoMIP experiments. This is meant to encourage various stakeholders to propose new targeted experiments that address their key open science questions, with the goal of making GeoMIP more relevant to a broader set of communities.

  20. Final Report for Project "Framework Application for Core-Edge Transport Simulations (FACETS)"

    Energy Technology Data Exchange (ETDEWEB)

    Estep, Donald [Colorado State Univ., Fort Collins, CO (United States)

    2014-01-17

    This is the final report for the Colorado State University Component of the FACETS Project. FACETS was focused on the development of a multiphysics, parallel framework application that could provide the capability to enable whole-device fusion reactor modeling and, in the process, the development of the modeling infrastructure and computational understanding needed for ITER. It was intended that FACETS be highly flexible, through the use of modern computational methods, including component technology and object oriented design, to facilitate switching from one model to another for a given aspect of the physics, and making it possible to use simplified models for rapid turnaround or high-fidelity models that will take advantage of the largest supercomputer hardware. FACETS was designed in a heterogeneous parallel context, where different parts of the application can take advantage through parallelism based on task farming, domain decomposition, and/or pipelining as needed and applicable. As with all fusion simulations, an integral part of the FACETS project was treatment of the coupling of different physical processes at different scales interacting closely. A primary example for the FACETS project is the coupling of existing core and edge simulations, with the transport and wall interactions described by reduced models. However, core and edge simulations themselves involve significant coupling of different processes with large scale differences. Numerical treatment of coupling is impacted by a number of factors including, scale differences, form of information transferred between processes, implementation of solvers for different codes, and high performance computing concerns. Operator decomposition involving the computation of the individual processes individually using appropriate simulation codes and then linking/synchronizing the component simulations at regular points in space and time, is the defacto approach to high performance simulation of multiphysics

  1. Simulated hydrologic response to projected changes in precipitation and temperature in the Congo River basin

    Science.gov (United States)

    Aloysius, Noel; Saiers, James

    2017-08-01

    Despite their global significance, the impacts of climate change on water resources and associated ecosystem services in the Congo River basin (CRB) have been understudied. Of particular need for decision makers is the availability of spatial and temporal variability of runoff projections. Here, with the aid of a spatially explicit hydrological model forced with precipitation and temperature projections from 25 global climate models (GCMs) under two greenhouse gas emission scenarios, we explore the variability in modeled runoff in the near future (2016-2035) and mid-century (2046-2065). We find that total runoff from the CRB is projected to increase by 5 % [-9 %; 20 %] (mean - min and max - across model ensembles) over the next two decades and by 7 % [-12 %; 24 %] by mid-century. Projected changes in runoff from subwatersheds distributed within the CRB vary in magnitude and sign. Over the equatorial region and in parts of northern and southwestern CRB, most models project an overall increase in precipitation and, subsequently, runoff. A simulated decrease in precipitation leads to a decline in runoff from headwater regions located in the northeastern and southeastern CRB. Climate model selection plays an important role in future projections for both magnitude and direction of change. The multimodel ensemble approach reveals that precipitation and runoff changes under business-as-usual and avoided greenhouse gas emission scenarios (RCP8.5 vs. RCP4.5) are relatively similar in the near term but deviate in the midterm, which underscores the need for rapid action on climate change adaptation. Our assessment demonstrates the need to include uncertainties in climate model and emission scenario selection during decision-making processes related to climate change mitigation and adaptation.

  2. Simulated hydrologic response to projected changes in precipitation and temperature in the Congo River basin

    Directory of Open Access Journals (Sweden)

    N. Aloysius

    2017-08-01

    Full Text Available Despite their global significance, the impacts of climate change on water resources and associated ecosystem services in the Congo River basin (CRB have been understudied. Of particular need for decision makers is the availability of spatial and temporal variability of runoff projections. Here, with the aid of a spatially explicit hydrological model forced with precipitation and temperature projections from 25 global climate models (GCMs under two greenhouse gas emission scenarios, we explore the variability in modeled runoff in the near future (2016–2035 and mid-century (2046–2065. We find that total runoff from the CRB is projected to increase by 5 % [−9 %; 20 %] (mean – min and max – across model ensembles over the next two decades and by 7 % [−12 %; 24 %] by mid-century. Projected changes in runoff from subwatersheds distributed within the CRB vary in magnitude and sign. Over the equatorial region and in parts of northern and southwestern CRB, most models project an overall increase in precipitation and, subsequently, runoff. A simulated decrease in precipitation leads to a decline in runoff from headwater regions located in the northeastern and southeastern CRB. Climate model selection plays an important role in future projections for both magnitude and direction of change. The multimodel ensemble approach reveals that precipitation and runoff changes under business-as-usual and avoided greenhouse gas emission scenarios (RCP8.5 vs. RCP4.5 are relatively similar in the near term but deviate in the midterm, which underscores the need for rapid action on climate change adaptation. Our assessment demonstrates the need to include uncertainties in climate model and emission scenario selection during decision-making processes related to climate change mitigation and adaptation.

  3. Projected changes in haze pollution potential in China: an ensemble of regional climate model simulations

    Science.gov (United States)

    Han, Zhenyu; Zhou, Botao; Xu, Ying; Wu, Jia; Shi, Ying

    2017-08-01

    Based on the dynamic downscaling by the regional climate model RegCM4 from three CMIP5 global models under the historical and the RCP4.5 simulations, this article evaluated the performance of the RegCM4 downscaling simulations on the air environment carrying capacity (AEC) and weak ventilation days (WVDs) in China, which are applied to measure haze pollution potential. Their changes during the middle and the end of the 21st century were also projected. The evaluations show that the RegCM4 downscaling simulations can generally capture the observed features of the AEC and WVD distributions over the period 1986-2005. The projections indicate that the annual AEC tends to decrease and the annual WVDs tend to increase over almost the whole country except central China, concurrent with greater change by the late 21st century than by the middle of the 21st century. It suggests that annual haze pollution potential would be enlarged under the RCP4.5 scenario compared to the present. For seasonal change in the four main economic zones of China, it is projected consistently that there would be a higher probability of haze pollution risk over the Beijing-Tianjin-Hebei (BTH) region and the Yangtze River Delta (YRD) region in winter and over the Pearl River Delta (PRD) region in spring and summer in the context of the warming scenario. Over Northeast China (NEC), future climate change might reduce the AEC or increase the WVDs throughout the whole year, which favours the occurrence of haze pollution and thus the haze pollution risk would be aggravated. The relative contribution of different components related to the AEC change further indicates that changes in the boundary layer depth and the wind speed play leading roles in the AEC change over the BTH and NEC regions. In addition to those two factors, the precipitation change also exerts important impacts on the AEC change over the YRD and PRD zones.

  4. World, We Have Problems: Simulation for Large Complex, Risky Projects, and Events

    Science.gov (United States)

    Elfrey, Priscilla

    2010-01-01

    Prior to a spacewalk during the NASA STS/129 mission in November 2009, Columbia Broadcasting System (CBS) correspondent William Harwood reported astronauts, "were awakened again", as they had been the day previously. Fearing something not properly connected was causing a leak, the crew, both on the ground and in space, stopped and checked everything. The alarm proved false. The crew did complete its work ahead of schedule, but the incident reminds us that correctly connecting hundreds and thousands of entities, subsystems and systems, finding leaks, loosening stuck valves, and adding replacements to very large complex systems over time does not occur magically. Everywhere major projects present similar pressures. Lives are at - risk. Responsibility is heavy. Large natural and human-created disasters introduce parallel difficulties as people work across boundaries their countries, disciplines, languages, and cultures with known immediate dangers as well as the unexpected. NASA has long accepted that when humans have to go where humans cannot go that simulation is the sole solution. The Agency uses simulation to achieve consensus, reduce ambiguity and uncertainty, understand problems, make decisions, support design, do planning and troubleshooting, as well as for operations, training, testing, and evaluation. Simulation is at the heart of all such complex systems, products, projects, programs, and events. Difficult, hazardous short and, especially, long-term activities have a persistent need for simulation from the first insight into a possibly workable idea or answer until the final report perhaps beyond our lifetime is put in the archive. With simulation we create a common mental model, try-out breakdowns of machinery or teamwork, and find opportunity for improvement. Lifecycle simulation proves to be increasingly important as risks and consequences intensify. Across the world, disasters are increasing. We anticipate more of them, as the results of global warming

  5. CHASE-PL Climate Projection dataset over Poland - bias adjustment of EURO-CORDEX simulations

    Science.gov (United States)

    Mezghani, Abdelkader; Dobler, Andreas; Haugen, Jan Erik; Benestad, Rasmus E.; Parding, Kajsa M.; Piniewski, Mikołaj; Kardel, Ignacy; Kundzewicz, Zbigniew W.

    2017-11-01

    The CHASE-PL (Climate change impact assessment for selected sectors in Poland) Climate Projections - Gridded Daily Precipitation and Temperature dataset 5 km (CPLCP-GDPT5) consists of projected daily minimum and maximum air temperatures and precipitation totals of nine EURO-CORDEX regional climate model outputs bias corrected and downscaled to a 5 km × 5 km grid. Simulations of one historical period (1971-2000) and two future horizons (2021-2050 and 2071-2100) assuming two representative concentration pathways (RCP4.5 and RCP8.5) were produced. We used the quantile mapping method and corrected any systematic seasonal bias in these simulations before assessing the changes in annual and seasonal means of precipitation and temperature over Poland. Projected changes estimated from the multi-model ensemble mean showed that annual means of temperature are expected to increase steadily by 1 °C until 2021-2050 and by 2 °C until 2071-2100 assuming the RCP4.5 emission scenario. Assuming the RCP8.5 emission scenario, this can reach up to almost 4 °C by 2071-2100. Similarly to temperature, projected changes in regional annual means of precipitation are expected to increase by 6 to 10 % and by 8 to 16 % for the two future horizons and RCPs, respectively. Similarly, individual model simulations also exhibited warmer and wetter conditions on an annual scale, showing an intensification of the magnitude of the change at the end of the 21st century. The same applied for projected changes in seasonal means of temperature showing a higher winter warming rate by up to 0.5 °C compared to the other seasons. However, projected changes in seasonal means of precipitation by the individual models largely differ and are sometimes inconsistent, exhibiting spatial variations which depend on the selected season, location, future horizon, and RCP. The overall range of the 90 % confidence interval predicted by the ensemble of multi-model simulations was found to likely vary between -7

  6. eScience for molecular-scale simulations and the eMinerals project.

    Science.gov (United States)

    Salje, E K H; Artacho, E; Austen, K F; Bruin, R P; Calleja, M; Chappell, H F; Chiang, G-T; Dove, M T; Frame, I; Goodwin, A L; Kleese van Dam, K; Marmier, A; Parker, S C; Pruneda, J M; Todorov, I T; Trachenko, K; Tyer, R P; Walker, A M; White, T O H

    2009-03-13

    We review the work carried out within the eMinerals project to develop eScience solutions that facilitate a new generation of molecular-scale simulation work. Technological developments include integration of compute and data systems, developing of collaborative frameworks and new researcher-friendly tools for grid job submission, XML data representation, information delivery, metadata harvesting and metadata management. A number of diverse science applications will illustrate how these tools are being used for large parameter-sweep studies, an emerging type of study for which the integration of computing, data and collaboration is essential.

  7. Selected results of simulation studies in “The Smart Peninsula” project

    Directory of Open Access Journals (Sweden)

    Andrzej Kąkol

    2012-03-01

    Full Text Available “The Intelligent Peninsula” project implementation required the development of a computational model of a medium voltage grid and of a section of a low voltage grid in the Hel Peninsula. The model was used to perform many simulation analyses in the MV grid. The analyses were used to develop MV grid operation control algorithms. The paper presents results of the analyses aimed at verification of a MLDC method-based voltage control algorithm. The paper presents results of the analyses aimed at verification of EC Władysławowo cogeneration plant’s suitability for standalone operation in the Hel Peninsula.

  8. Coupled Model Intercomparison Project 5 (CMIP5) simulations of climate following volcanic eruptions

    KAUST Repository

    Driscoll, Simon

    2012-09-16

    The ability of the climate models submitted to the Coupled Model Intercomparison Project 5 (CMIP5) database to simulate the Northern Hemisphere winter climate following a large tropical volcanic eruption is assessed. When sulfate aerosols are produced by volcanic injections into the tropical stratosphere and spread by the stratospheric circulation, it not only causes globally averaged tropospheric cooling but also a localized heating in the lower stratosphere, which can cause major dynamical feedbacks. Observations show a lower stratospheric and surface response during the following one or two Northern Hemisphere (NH) winters, that resembles the positive phase of the North Atlantic Oscillation (NAO). Simulations from 13 CMIP5 models that represent tropical eruptions in the 19th and 20th century are examined, focusing on the large-scale regional impacts associated with the large-scale circulation during the NH winter season. The models generally fail to capture the NH dynamical response following eruptions. They do not sufficiently simulate the observed post-volcanic strengthened NH polar vortex, positive NAO, or NH Eurasian warming pattern, and they tend to overestimate the cooling in the tropical troposphere. The findings are confirmed by a superposed epoch analysis of the NAO index for each model. The study confirms previous similar evaluations and raises concern for the ability of current climate models to simulate the response of a major mode of global circulation variability to external forcings. This is also of concern for the accuracy of geoengineering modeling studies that assess the atmospheric response to stratosphere-injected particles.

  9. Multidisciplinary In Situ Simulation-Based Training as a Postpartum Hemorrhage Quality Improvement Project.

    Science.gov (United States)

    Lutgendorf, Monica A; Spalding, Carmen; Drake, Elizabeth; Spence, Dennis; Heaton, Jason O; Morocco, Kristina V

    2017-03-01

    Postpartum hemorrhage is a common obstetric emergency affecting 3 to 5% of deliveries, with significant maternal morbidity and mortality. Effective management of postpartum hemorrhage requires strong teamwork and collaboration. We completed a multidisciplinary in situ postpartum hemorrhage simulation training exercise with structured team debriefing to evaluate hospital protocols, team performance, operational readiness, and real-time identification of system improvements. Our objective was to assess participant comfort with managing obstetric hemorrhage following our multidisciplinary in situ simulation training exercise. This was a quality improvement project that utilized a comprehensive multidisciplinary in situ postpartum hemorrhage simulation exercise. Participants from the Departments of Obstetrics and Gynecology, Anesthesia, Nursing, Pediatrics, and Transfusion Services completed the training exercise in 16 scenarios run over 2 days. The intervention was a high fidelity, multidisciplinary in situ simulation training to evaluate hospital protocols, team performance, operational readiness, and system improvements. Structured debriefing was conducted with the participants to discuss communication and team functioning. Our main outcome measure was participant self-reported comfort levels for managing postpartum hemorrhage before and after simulation training. A 5-point Likert scale (1 being very uncomfortable and 5 being very comfortable) was used to measure participant comfort. A paired t test was used to assess differences in participant responses before and after the simulation exercise. We also measured the time to prepare simulated blood products and followed the number of postpartum hemorrhage cases before and after the simulation exercise. We trained 113 health care professionals including obstetricians, midwives, residents, anesthesiologists, nurse anesthetists, nurses, and medical assistants. Participants reported a higher comfort level in managing

  10. Use of Simulation in Nursing Education: Initial Experiences on a European Union Lifelong Learning Programme--Leonardo Da Vinci Project

    Science.gov (United States)

    Terzioglu, Fusun; Tuna, Zahide; Duygulu, Sergul; Boztepe, Handan; Kapucu, Sevgisun; Ozdemir, Leyla; Akdemir, Nuran; Kocoglu, Deniz; Alinier, Guillaume; Festini, Filippo

    2013-01-01

    Aim: The aim of this paper is to share the initial experiences on a European Union (EU) Lifelong Learning Programme Leonardo Da Vinci Transfer of Innovation Project related to the use of simulation-based learning with nursing students from Turkey. The project started at the end of the 2010 involving 7 partners from 3 different countries including…

  11. On the Dual of the Solvency Cone

    OpenAIRE

    Löhne, Andreas; Rudloff, Birgit

    2014-01-01

    A solvency cone is a polyhedral convex cone which is used in Mathematical Finance to model proportional transaction costs. It consists of those portfolios which can be traded into nonnegative positions. In this note, we provide a characterization of its dual cone in terms of extreme directions and discuss some consequences, among them: (i) an algorithm to construct extreme directions of the dual cone when a corresponding "contribution scheme" is given; (ii) estimates for the number of extreme...

  12. A line fiducial method for geometric calibration of cone-beam CT systems with diverse scan trajectories.

    Science.gov (United States)

    Jacobson, Matthew W; Ketcha, Michael Daniel; Capostagno, Sarah; Martin, Alexander; Uneri, Ali; Goerres, Joseph; De Silva, Tharindu; Reaungamornrat, Sureerat; Han, Runze; Manbachi, Amir; Stayman, Joseph Webster; Vogt, Sebastian; Kleinszig, Gerhard; Siewerdsen, Jeffrey H

    2017-11-08

    Modern cone-beam CT systems, especially C-arms, are capable of diverse source-detector orbits. However, geometric calibration of these systems using conventional configurations of spherical fiducials (BBs) may be challenged for novel source-detector orbits and system geometries. In part, this is because the BB configurations are designed with careful forethought regarding the intended orbit so that BB marker projections do not overlap in projection views. Examples include helical arrangements of BBs (Rougee et al Proc. SPIE 1897 161-9) such that markers do not overlap in projections acquired from a circular orbit and circular arrangements of BBs (Cho et al Med Phys 32 968-83). As a more general alternative, this work proposes a calibration method based on an array of line-shaped, radio-opaque wire segments. With this method, geometric parameter estimation is accomplished by relating the 3D line equations representing the wires to the 2D line equations of their projections. The use of line fiducials simplifies many challenges with fiducial recognition and extraction in an orbit-independent manner. For example, their projections can overlap only mildly, for any gantry pose, as long as the wires are mutually non-coplanar in 3D. The method was tested in application to circular and non-circular trajectories in simulation and in real orbits executed using a mobile C-arm prototype for cone-beam CT. Results indicated high calibration accuracy, as measured by forward and backprojection/triangulation error metrics. Triangulation errors on the order of microns and backprojected ray deviations uniformly less than 0.2 mm were observed in both real and simulated orbits. Mean forward projection errors less than 0.1 mm were observed in a comprehensive sweep of different C-arm gantry angulations. Finally, successful integration of the method into a CT imaging chain was demonstrated in head phantom scans. © 2017 Institute of Physics and Engineering in Medicine.

  13. An Automated BIM Model to Conceptually Design, Analyze, Simulate, and Assess Sustainable Building Projects

    Directory of Open Access Journals (Sweden)

    Farzad Jalaei

    2014-01-01

    Full Text Available Quantifying the environmental impacts and simulating the energy consumption of building’s components at the conceptual design stage are very helpful for designers needing to make decisions related to the selection of the best design alternative that would lead to a more energy efficient building. Building Information Modeling (BIM offers designers the ability to assess different design alternatives at the conceptual stage of the project so that energy and life cycle assessment (LCA strategies and systems are attained. This paper proposes an automated model that links BIM, LCA, energy analysis, and lighting simulation tools with green building certification systems. The implementation is within developing plug-ins on BIM tool capable of measuring the environmental impacts (EI and embodied energy of building components. Using this method, designers will be provided with a new way to visualize and to identify the potential gain or loss of energy for the building as a whole and for each of its associated components. Furthermore, designers will be able to detect and evaluate the sustainability of the proposed buildings based on Leadership in Energy and Environmental Design (LEED rating system. An actual building project will be used to illustrate the workability of the proposed methodology.

  14. BIM-Based 4D Simulation to Improve Module Manufacturing Productivity for Sustainable Building Projects

    Directory of Open Access Journals (Sweden)

    Joosung Lee

    2017-03-01

    Full Text Available Modular construction methods, where products are manufactured beforehand in a factory and then transported to the site for installation, are becoming increasingly popular for construction projects in many countries as this method facilitates the use of the advanced technologies that support sustainability in building projects. This approach requires dual factory–site process management to be carefully coordinated and the factory module manufacturing process must therefore be managed in a detailed and quantitative manner. However, currently, the limited algorithms available to support this process are based on mathematical methodologies that do not consider the complex mix of equipment, factories, personnel, and materials involved. This paper presents three new building information modeling-based 4D simulation frameworks to manage the three elements—process, quantity, and quality—that determine the productivity of factory module manufacturing. These frameworks leverage the advantages of 4D simulation and provide more precise information than existing conventional documents. By utilizing a 4D model that facilitates the visualization of a wide range of data variables, manufacturers can plan the module manufacturing process in detail and fully understand the material, equipment, and workflow needed to accomplish the manufacturing tasks. Managers can also access information about material quantities for each process and use this information for earned value management, warehousing/storage, fabrication, and assembly planning. By having a 4D view that connects 2D drawing models, manufacturing errors and rework can be minimized and problems such as construction delays, quality lapses, and cost overruns vastly reduced.

  15. Seawave Slot-Cone Generator

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Contestabile, Pasquale

    2009-01-01

    This paper discusses a new type of Wave Energy Converter (WEC) named Seawave Slot-Cone Generator (SSG). The SSG is a WEC of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level in which the water of incoming waves is store...

  16. Intrinsic volumes of symmetric cones

    OpenAIRE

    Amelunxen, Dennis; Bürgisser, Peter

    2012-01-01

    We compute the intrinsic volumes of the cone of positive semidefinite matrices over the real numbers, over the complex numbers, and over the quaternions, in terms of integrals related to Mehta's integral. Several applications for the probabilistic analysis of semidefinite programming are given.

  17. Scenario Based Education as a Framework for Understanding Students Engagement and Learning in a Project Management Simulation Game

    DEFF Research Database (Denmark)

    Misfeldt, Morten

    2015-01-01

    In this paper I describe s how students use a project management simulation game based on an attack‑defense mechanism where two teams of players compete by challenging each other⠒s projects. The project management simulation game is intended to be playe d by pre‑service construction workers......, and experiment with relevant parameters. Emphasizing the competi tion game aspect we can see how play and competition allow players to experience intrinsic motivation and engagement, as well as thinking strategically about their choices, and hence put attention towards all the things that can go wrong...

  18. Ablation and cone formation mechanism on CR-39 by ArF laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shakeri Jooybari, B., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Nuclear Science and Technology Research Institute NSRT, Tehran (Iran, Islamic Republic of); Afarideh, H., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Lamehi-Rachti, M. [Nuclear Science and Technology Research Institute NSRT, Tehran (Iran, Islamic Republic of); Ghergherehchi, M. [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); College of Information and Communication Engineering, Sungkyunkwan University, Suwon (Korea, Republic of)

    2015-03-07

    In this work, chemical properties, surface modification, and micro structures formation on ablated polyallyl di-glycol carbonate (CR-39) polymer by ArF laser irradiation (λ = 193 nm) at various fluences and pulse number were investigated. CR-39 samples have been irradiated with an ArF laser (193 nm) at a repetition rate of 1 Hz. Threshold fluence of ablation and effective absorption coefficient of CR-39 were determined. Conical microstructures (Taylor cone) formed on laser-ablated CR-39 exhibit: smooth, Taylor cone shape walls and sharp tips together with interference and well defined fringe-structure with a period of 230 nm, around cone base. Mechanism of cone formation and cone evolution of CR-39 ablated surface were investigated by change of fluences (at a given pulse number) and pulse number (at a given fluence). Cone height, cone base, and region of interface were increased in micrometer steps by increasing the total fluence. Depression on the base of the cone and the circular fringe were simulated. FTIR spectra were measured and energy dispersive x-ray analysis of irradiated and un-irradiated samples was performed.

  19. Simulation technology used for risky assessment in deep exploration project in China

    Science.gov (United States)

    jiao, J.; Huang, D.; Liu, J.

    2013-12-01

    Deep exploration has been carried out in China for five years in which various heavy duty instruments and equipments are employed for gravity, magnetic, seismic and electromagnetic data prospecting as well as ultra deep drilling rig established for obtaining deep samples, and so on. The deep exploration is a large and complex system engineering crossing multiple subjects with great investment. It is necessary to employ advanced technical means technology for verification, appraisal, and optimization of geographical prospecting equipment development. To reduce risk of the application and exploration, efficient and allegeable management concept and skills have to be enhanced in order to consolidate management measure and workflow to benefit the ambitious project. Therefore, evidence, prediction, evaluation and related decision strategies have to be taken into accouter simultaneously to meet practical scientific requests and technique limits and extendable attempts. Simulation technique is then proposed as a tool that can be used to carry out dynamic test on actual or imagined system. In practice, it is necessary to combine the simulation technique with the instruments and equipment to accomplish R&D tasks. In this paper, simulation technique is introduced into the R&D process of heavy-duty equipment and high-end engineering project technology. Based on the information provided by a drilling group recently, a digital model is constructed by combination of geographical data, 3d visualization, database management, and visual reality technologies together. It result in push ahead a R&D strategy, in which data processing , instrument application, expected result and uncertainty, and even operation workflow effect environment atmosphere are simulated systematically or simultaneously, in order to obtain an optimal consequence as well as equipment updating strategy. The simulation technology is able to adjust, verify, appraise and optimize the primary plan due to changing in

  20. The Cluster-EAGLE project: global properties of simulated clusters with resolved galaxies

    Science.gov (United States)

    Barnes, David J.; Kay, Scott T.; Bahé, Yannick M.; Dalla Vecchia, Claudio; McCarthy, Ian G.; Schaye, Joop; Bower, Richard G.; Jenkins, Adrian; Thomas, Peter A.; Schaller, Matthieu; Crain, Robert A.; Theuns, Tom; White, Simon D. M.

    2017-10-01

    We introduce the Cluster-EAGLE (c-eagle) simulation project, a set of cosmological hydrodynamical zoom simulations of the formation of 30 galaxy clusters in the mass range of 1014 simulations adopt the state-of-the-art eagle galaxy formation model, with a gas particle mass of 1.8 × 106 M⊙ and physical softening length of 0.7 kpc. In this paper, we introduce the sample and present the low-redshift global properties of the clusters. We calculate the X-ray properties in a manner consistent with observational techniques, demonstrating the bias and scatter introduced by using estimated masses. We find the total stellar content and black hole masses of the clusters to be in good agreement with the observed relations. However, the clusters are too gas rich, suggesting that the active galactic nucleus (AGN) feedback model is not efficient enough at expelling gas from the high-redshift progenitors of the clusters. The X-ray properties, such as the spectroscopic temperature and the soft-band luminosity, and the Sunyaev-Zel'dovich properties are in reasonable agreement with the observed relations. However, the clusters have too high central temperatures and larger-than-observed entropy cores, which is likely driven by the AGN feedback after the cluster core has formed. The total metal content and its distribution throughout the intracluster medium are a good match to the observations.

  1. MEchatronic REspiratory System SImulator for Neonatal Applications (MERESSINA project: a novel bioengineering goal

    Directory of Open Access Journals (Sweden)

    Scaramuzzo RT

    2013-08-01

    Full Text Available Rosa T Scaramuzzo,1,2 Massimiliano Ciantelli,1 Ilaria Baldoli,3 Lisa Bellanti,3 Marzia Gentile,1 Francesca Cecchi,3 Emilio Sigali,1 Selene Tognarelli,3 Paolo Ghirri,1–4 Stefano Mazzoleni,3 Arianna Menciassi,3 Armando Cuttano,1 Antonio Boldrini,1–4 Cecilia Laschi,3 Paolo Dario3 1Centro di Formazione e Simulazione Neonatale "NINA," UO Neonatologia, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy; 2Istituto di Scienze della Vita, 3The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy; 4Università di Pisa, Pisa, Italy Abstract: Respiratory function is mandatory for extrauterine life, but is sometimes impaired in newborns due to prematurity, congenital malformations, or acquired pathologies. Mechanical ventilation is standard care, but long-term complications, such as bronchopulmonary dysplasia, are still largely reported. Therefore, continuous medical education is mandatory to correctly manage devices for assistance. Commercially available breathing function simulators are rarely suitable for the anatomical and physiological realities. The aim of this study is to develop a high-fidelity mechatronic simulator of neonatal airways and lungs for staff training and mechanical ventilator testing. The project is divided into three different phases: (1 a review study on respiratory physiology and pathophysiology and on already available single and multi-compartment models; (2 the prototyping phase; and (3 the on-field system validation. Keywords: simulation, lung, newborn, continuous medical education, respiratory system

  2. Simulation of extreme rainfall and projection of future changes using the GLIMCLIM model

    Science.gov (United States)

    Rashid, Md. Mamunur; Beecham, Simon; Chowdhury, Rezaul Kabir

    2017-10-01

    In this study, the performance of the Generalized LInear Modelling of daily CLImate sequence (GLIMCLIM) statistical downscaling model was assessed to simulate extreme rainfall indices and annual maximum daily rainfall (AMDR) when downscaled daily rainfall from National Centers for Environmental Prediction (NCEP) reanalysis and Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation models (GCM) (four GCMs and two scenarios) output datasets and then their changes were estimated for the future period 2041-2060. The model was able to reproduce the monthly variations in the extreme rainfall indices reasonably well when forced by the NCEP reanalysis datasets. Frequency Adapted Quantile Mapping (FAQM) was used to remove bias in the simulated daily rainfall when forced by CMIP5 GCMs, which reduced the discrepancy between observed and simulated extreme rainfall indices. Although the observed AMDR were within the 2.5th and 97.5th percentiles of the simulated AMDR, the model consistently under-predicted the inter-annual variability of AMDR. A non-stationary model was developed using the generalized linear model for local, shape and scale to estimate the AMDR with an annual exceedance probability of 0.01. The study shows that in general, AMDR is likely to decrease in the future. The Onkaparinga catchment will also experience drier conditions due to an increase in consecutive dry days coinciding with decreases in heavy (>long term 90th percentile) rainfall days, empirical 90th quantile of rainfall and maximum 5-day consecutive total rainfall for the future period (2041-2060) compared to the base period (1961-2000).

  3. Projected changes in haze pollution potential in China: an ensemble of regional climate model simulations

    Directory of Open Access Journals (Sweden)

    Z. Han

    2017-08-01

    Full Text Available Based on the dynamic downscaling by the regional climate model RegCM4 from three CMIP5 global models under the historical and the RCP4.5 simulations, this article evaluated the performance of the RegCM4 downscaling simulations on the air environment carrying capacity (AEC and weak ventilation days (WVDs in China, which are applied to measure haze pollution potential. Their changes during the middle and the end of the 21st century were also projected. The evaluations show that the RegCM4 downscaling simulations can generally capture the observed features of the AEC and WVD distributions over the period 1986–2005. The projections indicate that the annual AEC tends to decrease and the annual WVDs tend to increase over almost the whole country except central China, concurrent with greater change by the late 21st century than by the middle of the 21st century. It suggests that annual haze pollution potential would be enlarged under the RCP4.5 scenario compared to the present. For seasonal change in the four main economic zones of China, it is projected consistently that there would be a higher probability of haze pollution risk over the Beijing–Tianjin–Hebei (BTH region and the Yangtze River Delta (YRD region in winter and over the Pearl River Delta (PRD region in spring and summer in the context of the warming scenario. Over Northeast China (NEC, future climate change might reduce the AEC or increase the WVDs throughout the whole year, which favours the occurrence of haze pollution and thus the haze pollution risk would be aggravated. The relative contribution of different components related to the AEC change further indicates that changes in the boundary layer depth and the wind speed play leading roles in the AEC change over the BTH and NEC regions. In addition to those two factors, the precipitation change also exerts important impacts on the AEC change over the YRD and PRD zones.

  4. Simulator Network Project Report: A tool for improvement of teaching materials and targeted resource usage in Skills Labs

    Science.gov (United States)

    Damanakis, Alexander; Blaum, Wolf E.; Stosch, Christoph; Lauener, Hansjörg; Richter, Sabine; Schnabel, Kai P.

    2013-01-01

    During the last decade, medical education in the German-speaking world has been striving to become more practice-oriented. This is currently being achieved in many schools through the implementation of simulation-based instruction in Skills Labs. Simulators are thus an essential part of this type of medical training, and their acquisition and operation by a Skills Lab require a large outlay of resources. Therefore, the Practical Skills Committee of the Medical Education Society (GMA) introduced a new project, which aims to improve the flow of information between the Skills Labs and enable a transparent assessment of the simulators via an online database (the Simulator Network). PMID:23467581

  5. Research on distribution equipment training system based on holographic projection interactive simulation technology

    Science.gov (United States)

    Ma, Meng-Chao; Zhang, Yan; Li, Guang-Lei; Gao, Nan-Nan; Huang, Jin-Xin; Ma, Zhi-Guang; Shang, Ling-Ling; Guo, Liang-Feng

    2017-11-01

    This paper presents a three-dimensional (3D) interactive simulation training system based on holographic projection technology, nano-touch technology and interactive training mode, which realize the 3D display without stereoscopic glasses and touch type human computer interaction. 4 sets of holographic training courseware and 2 sets of fault presentation courseware was developed. Every courseware includes four parts: the cognition mode, the operation mode, the disassembling mode and daily maintenance mode. The system can carry out the training course of distribution automation equipment structure, disassembling and assembling, daily maintenance, operation, and the fault handling. A new training mode of power equipment training was created, which opened a new era of power equipment training.

  6. Scientific computing and algorithms in industrial simulations projects and products of Fraunhofer SCAI

    CERN Document Server

    Schüller, Anton; Schweitzer, Marc

    2017-01-01

    The contributions gathered here provide an overview of current research projects and selected software products of the Fraunhofer Institute for Algorithms and Scientific Computing SCAI. They show the wide range of challenges that scientific computing currently faces, the solutions it offers, and its important role in developing applications for industry. Given the exciting field of applied collaborative research and development it discusses, the book will appeal to scientists, practitioners, and students alike. The Fraunhofer Institute for Algorithms and Scientific Computing SCAI combines excellent research and application-oriented development to provide added value for our partners. SCAI develops numerical techniques, parallel algorithms and specialized software tools to support and optimize industrial simulations. Moreover, it implements custom software solutions for production and logistics, and offers calculations on high-performance computers. Its services and products are based on state-of-the-art metho...

  7. Is social projection based on simulation or theory? Why new methods are needed for differentiating.

    Science.gov (United States)

    Bazinger, Claudia; Kühberger, Anton

    2012-12-01

    The literature on social cognition reports many instances of a phenomenon titled 'social projection' or 'egocentric bias'. These terms indicate egocentric predictions, i.e., an over-reliance on the self when predicting the cognition, emotion, or behavior of other people. The classic method to diagnose egocentric prediction is to establish high correlations between our own and other people's cognition, emotion, or behavior. We argue that this method is incorrect because there is a different way to come to a correlation between own and predicted states, namely, through the use of theoretical knowledge. Thus, the use of correlational measures is not sufficient to identify the source of social predictions. Based on the distinction between simulation theory and theory theory, we propose the following alternative methods for inferring prediction strategies: independent vs. juxtaposed predictions, the use of 'hot' mental processes, and the use of participants' self-reports.

  8. Simulation Study of Structure and Properties of Plasma Liners for the PLX- α Project

    Science.gov (United States)

    Samulyak, Roman; Shih, Wen; Hsu, Scott; PLX-Alpha Team

    2017-10-01

    Detailed numerical studies of the propagation and merger of high-Mach-number plasma jets and the formation and implosion of plasma liners have been performed using the FronTier code in support of the Plasma Liner Experiment-ALPHA (PLX- α) project. Physics models include radiation, physical diffusion, plasma-EOS models, and an anisotropic diffusion model that mimics deviations from fully collisional hydrodynamics in outer layers of plasma jets. Detailed structure and non-uniformity of plasma liners of due to primary and secondary shock waves have been studies as well as averaged quantities of ram pressure and Mach number. Synthetic data from simulations have been compared with available experimental data from a multi-chord interferometer and survey and high-resolution spectrometers. Numerical studies of the sensitivity of liner properties to experimental errors in the initial masses of jets and the synchronization of plasma gun valves have also been performed. Supported by the ARPA-E ALPHA program.

  9. Cirrus Parcel Model Comparison Project. Phase 1; The Critical Components to Simulate Cirrus Initiation Explicitly

    Science.gov (United States)

    Lin, Ruei-Fong; Starr, David OC; DeMott, Paul J.; Cotton, Richard; Sassen, Kenneth; Jensen, Eric; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The Cirrus Parcel Model Comparison Project, a project of the GCSS (GEWEX Cloud System Studies) Working Group on Cirrus Cloud Systems, involves the systematic comparison of current models of ice crystal nucleation and growth for specified, typical, cirrus cloud environments. In Phase I of the project reported here, simulated cirrus cloud microphysical properties are compared for situations of "warm" (40 C) and "cold" (-60 C) cirrus, both subject to updrafts of 4, 20 and 100 centimeters per second. Five models participated. The various models employ explicit microphysical schemes wherein the size distribution of each class of particles (aerosols and ice crystals) is resolved into bins or treated separately. Simulations are made including both the homogeneous and heterogeneous ice nucleation mechanisms. A single initial aerosol population of sulfuric acid particles is prescribed for all simulations. To isolate the treatment of the homogeneous freezing (of haze droplets) nucleation process, the heterogeneous nucleation mechanism is disabled for a second parallel set of simulations. Qualitative agreement is found for the homogeneous-nucleation- only simulations, e.g., the number density of nucleated ice crystals increases with the strength of the prescribed updraft. However, significant quantitative differences are found. Detailed analysis reveals that the homogeneous nucleation rate, haze particle solution concentration, and water vapor uptake rate by ice crystal growth (particularly as controlled by the deposition coefficient) are critical components that lead to differences in predicted microphysics. Systematic bias exists between results based on a modified classical theory approach and models using an effective freezing temperature approach to the treatment of nucleation. Each approach is constrained by critical freezing data from laboratory studies, but each includes assumptions that can only be justified by further laboratory research. Consequently, it is not yet

  10. Development of a Full Ice-cream Cone Model for Halo Coronal Mass Ejections

    Science.gov (United States)

    Na, Hyeonock; Moon, Y.-J.; Lee, Harim

    2017-04-01

    It is essential to determine three-dimensional parameters (e.g., radial speed, angular width, and source location) of coronal mass ejections (CMEs) for the space weather forecast. In this study, we investigate which cone type represents a halo CME morphology using 29 CMEs (12 Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) halo CMEs and 17 Solar Terrestrial Relations Observatory (STEREO)/Sun-Earth Connection Coronal and Heliospheric Investigation COR2 halo CMEs) from 2010 December to 2011 June. These CMEs are identified as halo CMEs by one spacecraft (SOHO or one of STEREO A and B) and limb ones by the other spacecraft (One of STEREO A and B or SOHO). From cone shape parameters of these CMEs, such as their front curvature, we find that the CME observational structures are much closer to a full ice-cream cone type than a shallow ice-cream cone type. Thus, we develop a full ice-cream cone model based on a new methodology that the full ice-cream cone consists of many flat cones with different heights and angular widths to estimate the three-dimensional parameters of the halo CMEs. This model is constructed by carrying out the following steps: (1) construct a cone for a given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO/LASCO halo CMEs, we find that 3D parameters from our method are similar to those from other stereoscopic methods (I.e., a triangulation method and a Graduated Cylindrical Shell model).

  11. Design, Results, Evolution and Status of the ATLAS simulation in Point1 project.

    CERN Document Server

    Ballestrero, Sergio; The ATLAS collaboration; Brasolin, Franco; Contescu, Alexandru Cristian; Fazio, Daniel; Di Girolamo, Alessandro; Lee, Christopher Jon; Pozo Astigarraga, Mikel Eukeni; Scannicchio, Diana; Sedov, Alexey; Twomey, Matthew Shaun; Wang, Fuquan; Zaytsev, Alexander

    2015-01-01

    During the LHC long shutdown period (LS1), that started in 2013, the simulation in Point1 (Sim@P1) project takes advantage in an opportunistic way of the trigger and data acquisition (TDAQ) farm of the ATLAS experiment. The farm provides more than 1500 computer nodes, and they are particularly suitable for running event generation and Monte Carlo production jobs that are mostly CPU and not I/O bound. It is capable of running up to 2500 virtual machines (VM) provided with 8 CPU cores each, for a total of up to 20000 parallel running jobs. This contribution gives a thorough review of the design, the results and the evolution of the Sim@P1 project operating a large scale Openstack based virtualized platform deployed on top of the ATLAS TDAQ farm computing resources. During LS1, Sim@P1 was one of the most productive GRID sites: it delivered more than 50 million CPU-hours and it generated more than 1.7 billion Monte Carlo events to various analysis communities within the ATLAS collaboration. The particular design ...

  12. Design, Results, Evolution and Status of the ATLAS Simulation at Point1 Project

    CERN Document Server

    AUTHOR|(SzGeCERN)377840; Fressard-Batraneanu, Silvia Maria; Ballestrero, Sergio; Contescu, Alexandru Cristian; Fazio, Daniel; Di Girolamo, Alessandro; Lee, Christopher Jon; Pozo Astigarraga, Mikel Eukeni; Scannicchio, Diana; Sedov, Alexey; Twomey, Matthew Shaun; Wang, Fuquan; Zaytsev, Alexander

    2015-01-01

    Abstract. During the LHC Long Shutdown 1 period (LS1), that started in 2013, the Simulation at Point1 (Sim@P1) Project takes advantage, in an opportunistic way, of the TDAQ (Trigger and Data Acquisition) HLT (High Level Trigger) farm of the ATLAS experiment. This farm provides more than 1300 compute nodes, which are particularly suited for running event generation and Monte Carlo production jobs that are mostly CPU and not I/O bound. It is capable of running up to 2700 virtual machines (VMs) provided with 8 CPU cores each, for a total of up to 22000 parallel running jobs. This contribution gives a review of the design, the results, and the evolution of the Sim@P1 Project; operating a large scale OpenStack based virtualized platform deployed on top of the ATLAS TDAQ HLT farm computing resources. During LS1, Sim@P1 was one of the most productive ATLAS sites: it delivered more than 50 million CPU-hours and it generated more than 1.7 billion Monte Carlo events to various analysis communities. The design aspects a...

  13. QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials.

    Science.gov (United States)

    Giannozzi, Paolo; Baroni, Stefano; Bonini, Nicola; Calandra, Matteo; Car, Roberto; Cavazzoni, Carlo; Ceresoli, Davide; Chiarotti, Guido L; Cococcioni, Matteo; Dabo, Ismaila; Dal Corso, Andrea; de Gironcoli, Stefano; Fabris, Stefano; Fratesi, Guido; Gebauer, Ralph; Gerstmann, Uwe; Gougoussis, Christos; Kokalj, Anton; Lazzeri, Michele; Martin-Samos, Layla; Marzari, Nicola; Mauri, Francesco; Mazzarello, Riccardo; Paolini, Stefano; Pasquarello, Alfredo; Paulatto, Lorenzo; Sbraccia, Carlo; Scandolo, Sandro; Sclauzero, Gabriele; Seitsonen, Ari P; Smogunov, Alexander; Umari, Paolo; Wentzcovitch, Renata M

    2009-09-30

    QUANTUM ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). The acronym ESPRESSO stands for opEn Source Package for Research in Electronic Structure, Simulation, and Optimization. It is freely available to researchers around the world under the terms of the GNU General Public License. QUANTUM ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively parallel architectures, and a great effort being devoted to user friendliness. QUANTUM ESPRESSO is evolving towards a distribution of independent and interoperable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.

  14. QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials

    Energy Technology Data Exchange (ETDEWEB)

    Giannozzi, Paolo; Baroni, Stefano; Dal Corso, Andrea; De Gironcoli, Stefano; Fabris, Stefano; Gebauer, Ralph; Kokalj, Anton; Martin-Samos, Layla [CNR-INFM Democritos National Simulation Center, 34100 Trieste (Italy); Bonini, Nicola; Ceresoli, Davide [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Calandra, Matteo; Gougoussis, Christos; Lazzeri, Michele [Institut de Mineralogie et de Physique des Milieux Condenses, Universite Pierre et Marie Curie, CNRS, IPGP, 140 rue de Lourmel, 75015 Paris (France); Car, Roberto [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Cavazzoni, Carlo [CINECA National Supercomputing Center, Casalecchio di Reno, 40033 Bologna (Italy); Chiarotti, Guido L [SPIN s.r.l., via del Follatoio 12, 34148 Trieste (Italy); Cococcioni, Matteo [Department of Chemical Engineering and Materials Science, University of Minnesota, 151 Amundson Hall, 421 Washington Avenue SE, Minneapolis, MN 55455 (United States); Dabo, Ismaila [Universite Paris-Est, CERMICS, Projet Micmac ENPC-INRIA, 6-8 avenue Blaise Pascal, 77455 Marne-la-Vallee Cedex 2 (France); Fratesi, Guido [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano-Bicocca, via Cozzi 53, 20125 Milano (Italy); Gerstmann, Uwe [Theoretische Physik, Universitaet Paderborn, D-33098 Paderborn (Germany)

    2009-09-30

    QUANTUM ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). The acronym ESPRESSO stands for opEn Source Package for Research in Electronic Structure, Simulation, and Optimization. It is freely available to researchers around the world under the terms of the GNU General Public License. QUANTUM ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively parallel architectures, and a great effort being devoted to user friendliness. QUANTUM ESPRESSO is evolving towards a distribution of independent and interoperable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.

  15. Simulation-Based Fuzzy Logic Approach to Assessing the Effect of Project Quality Management on Construction Performance

    Directory of Open Access Journals (Sweden)

    Gilberto A. Corona-Suárez

    2014-01-01

    Full Text Available This paper reports the development of an approach to integrate the appropriate modeling techniques for estimating the effect of project quality management (PQM on construction performance. This modeling approach features a causal structure that depicts the interaction among the PQM factors affecting quality performance in a given construction operation. In addition, it makes use of fuzzy sets and fuzzy logic in order to incorporate the subjectivity and uncertainty implicit in the performance assessment of these PQM factors to discrete-event simulation models. The outcome is a simulation approach that allows experimenting with different performance levels of the PQM practices implemented in a construction project and obtaining the corresponding productivity estimates of the construction operations. These estimates are intended to facilitate the decision making regarding the improvement of a PQM system implemented in a construction project. A case study is used to demonstrate the usefulness of the proposed simulation approach for evaluating diverse performance improvement alternatives for a PQM system.

  16. Modeling multiple communities of interest for interactive simulation and gaming: the dynamic adversarial gaming algorithm project

    Science.gov (United States)

    Santos, Eugene, Jr.; Zhao, Qunhua; Pratto, Felicia; Pearson, Adam R.; McQueary, Bruce; Breeden, Andy; Krause, Lee

    2007-04-01

    Nowadays, there is an increasing demand for the military to conduct operations that are beyond traditional warfare. In these operations, analyzing and understanding those who are involved in the situation, how they are going to behave, and why they behave in certain ways is critical for success. The challenge lies in that behavior does not simply follow universal/fixed doctrines; it is significantly influenced by soft factors (i.e. cultural factors, societal norms, etc.). In addition, there is rarely just one isolated enemy; the behaviors and responses of all groups in the region, and the dynamics of the interaction among them composes an important part of the whole picture. The Dynamic Adversarial Gaming Algorithm (DAGA) project aims to provide a wargaming environment for automation of simulating dynamics of geopolitical crisis and eventually be applied to military simulation and training domain, and/or commercial gaming arena. The focus of DAGA is on modeling communities of interest (COIs), where various individuals, groups, and organizations as well as their interactions are captured. The framework should provide a context for COIs to interact with each other and influence others' behaviors. These behaviors must incorporate soft factors by modeling cultural knowledge. We do so by representing cultural variables and their influence on behavior using probabilistic networks. In this paper, we describe our COI modeling, the development of cultural networks, the interaction architecture, and a prototype of DAGA.

  17. An Effective CUDA Parallelization of Projection in Iterative Tomography Reconstruction.

    Science.gov (United States)

    Xie, Lizhe; Hu, Yining; Yan, Bin; Wang, Lin; Yang, Benqiang; Liu, Wenyuan; Zhang, Libo; Luo, Limin; Shu, Huazhong; Chen, Yang

    2015-01-01

    Projection and back-projection are the most computationally intensive parts in Computed Tomography (CT) reconstruction, and are essential to acceleration of CT reconstruction algorithms. Compared to back-projection, parallelization efficiency in projection is highly limited by racing condition and thread unsynchronization. In this paper, a strategy of Fixed Sampling Number Projection (FSNP) is proposed to ensure the operation synchronization in the ray-driven projection with Graphical Processing Unit (GPU). Texture fetching is also used utilized to further accelerate the interpolations in both projection and back-projection. We validate the performance of this FSNP approach using both simulated and real cone-beam CT data. Experimental results show that compare to the conventional approach, the proposed FSNP method together with texture fetching is 10~16 times faster than the conventional approach based on global memory, and thus leads to more efficient iterative algorithm in CT reconstruction.

  18. An Effective CUDA Parallelization of Projection in Iterative Tomography Reconstruction.

    Directory of Open Access Journals (Sweden)

    Lizhe Xie

    Full Text Available Projection and back-projection are the most computationally intensive parts in Computed Tomography (CT reconstruction, and are essential to acceleration of CT reconstruction algorithms. Compared to back-projection, parallelization efficiency in projection is highly limited by racing condition and thread unsynchronization. In this paper, a strategy of Fixed Sampling Number Projection (FSNP is proposed to ensure the operation synchronization in the ray-driven projection with Graphical Processing Unit (GPU. Texture fetching is also used utilized to further accelerate the interpolations in both projection and back-projection. We validate the performance of this FSNP approach using both simulated and real cone-beam CT data. Experimental results show that compare to the conventional approach, the proposed FSNP method together with texture fetching is 10~16 times faster than the conventional approach based on global memory, and thus leads to more efficient iterative algorithm in CT reconstruction.

  19. Greenland ice sheet surface mass balance: evaluating simulations and making projections with regional climate models

    Directory of Open Access Journals (Sweden)

    J. G. L. Rae

    2012-11-01

    Full Text Available Four high-resolution regional climate models (RCMs have been set up for the area of Greenland, with the aim of providing future projections of Greenland ice sheet surface mass balance (SMB, and its contribution to sea level rise, with greater accuracy than is possible from coarser-resolution general circulation models (GCMs. This is the first time an intercomparison has been carried out of RCM results for Greenland climate and SMB. Output from RCM simulations for the recent past with the four RCMs is evaluated against available observations. The evaluation highlights the importance of using a detailed snow physics scheme, especially regarding the representations of albedo and meltwater refreezing. Simulations with three of the RCMs for the 21st century using SRES scenario A1B from two GCMs produce trends of between −5.5 and −1.1 Gt yr−2 in SMB (equivalent to +0.015 and +0.003 mm sea level equivalent yr−2, with trends of smaller magnitude for scenario E1, in which emissions are mitigated. Results from one of the RCMs whose present-day simulation is most realistic indicate that an annual mean near-surface air temperature increase over Greenland of ~ 2°C would be required for the mass loss to increase such that it exceeds accumulation, thereby causing the SMB to become negative, which has been suggested as a threshold beyond which the ice sheet would eventually be eliminated.

  20. The AGORA High-resolution Galaxy Simulations Comparison Project. II. Isolated Disk Test

    Science.gov (United States)

    Kim, Ji-hoon; Agertz, Oscar; Teyssier, Romain; Butler, Michael J.; Ceverino, Daniel; Choi, Jun-Hwan; Feldmann, Robert; Keller, Ben W.; Lupi, Alessandro; Quinn, Thomas; Revaz, Yves; Wallace, Spencer; Gnedin, Nickolay Y.; Leitner, Samuel N.; Shen, Sijing; Smith, Britton D.; Thompson, Robert; Turk, Matthew J.; Abel, Tom; Arraki, Kenza S.; Benincasa, Samantha M.; Chakrabarti, Sukanya; DeGraf, Colin; Dekel, Avishai; Goldbaum, Nathan J.; Hopkins, Philip F.; Hummels, Cameron B.; Klypin, Anatoly; Li, Hui; Madau, Piero; Mandelker, Nir; Mayer, Lucio; Nagamine, Kentaro; Nickerson, Sarah; O'Shea, Brian W.; Primack, Joel R.; Roca-Fàbrega, Santi; Semenov, Vadim; Shimizu, Ikkoh; Simpson, Christine M.; Todoroki, Keita; Wadsley, James W.; Wise, John H.; AGORA Collaboration

    2016-12-01

    Using an isolated Milky Way-mass galaxy simulation, we compare results from nine state-of-the-art gravito-hydrodynamics codes widely used in the numerical community. We utilize the infrastructure we have built for the AGORA High-resolution Galaxy Simulations Comparison Project. This includes the common disk initial conditions, common physics models (e.g., radiative cooling and UV background by the standardized package Grackle) and common analysis toolkit yt, all of which are publicly available. Subgrid physics models such as Jeans pressure floor, star formation, supernova feedback energy, and metal production are carefully constrained across code platforms. With numerical accuracy that resolves the disk scale height, we find that the codes overall agree well with one another in many dimensions including: gas and stellar surface densities, rotation curves, velocity dispersions, density and temperature distribution functions, disk vertical heights, stellar clumps, star formation rates, and Kennicutt-Schmidt relations. Quantities such as velocity dispersions are very robust (agreement within a few tens of percent at all radii) while measures like newly formed stellar clump mass functions show more significant variation (difference by up to a factor of ˜3). Systematic differences exist, for example, between mesh-based and particle-based codes in the low-density region, and between more diffusive and less diffusive schemes in the high-density tail of the density distribution. Yet intrinsic code differences are generally small compared to the variations in numerical implementations of the common subgrid physics such as supernova feedback. Our experiment reassures that, if adequately designed in accordance with our proposed common parameters, results of a modern high-resolution galaxy formation simulation are more sensitive to input physics than to intrinsic differences in numerical schemes.

  1. Improving Nursing Communication Skills in an Intensive Care Unit Using Simulation and Nursing Crew Resource Management Strategies: An Implementation Project.

    Science.gov (United States)

    Turkelson, Carman; Aebersold, Michelle; Redman, Richard; Tschannen, Dana

    Effective interprofessional communication is critical to patient safety. This pre-/postimplementation project used a multifaceted educational strategy with high-fidelity simulation to introduce evidence-based communication tools, adapted from Nursing Crew Resource Management, to intensive care unit nurses. Results indicated that participants were satisfied with the education, and their perceptions of interprofessional communication and knowledge improved. Teams (n = 16) that used the communication tools during simulation were more likely to identify the problem, initiate key interventions, and have positive outcomes.

  2. Méthode analytique généralisée pour le calcul du coning. Nouvelle solution pour calculer le coning de gaz, d'eau et double coning dans les puits verticaux et horizontaux Generalized Analytical Method for Coning Calculation. New Solution to Calculation Both the Gas Coning, Water Coning and Dual Coning for Vertical and Horizontal Wells

    Directory of Open Access Journals (Sweden)

    Pietraru V.

    2006-11-01

    for a given coning height (hcw. First, how must be calculed using Equation 4. 2. - Calculating the height of the coning peak (hcw for a given watercut (fw. In a similar way, the GOR is calculated for gas coning. The correlations given above were developed while considering that the production flow rate is constant. However, application of the superposition principle can be used to apply the proposed methods to cases of variable flow rate, hence the following options that may be analyzed with this method. Constant oil flow rate : This option has a theoretical nature. It can be applied in practice only up to breakthrough. The watertut, which is insignificant up to breakthrough, effectively increases very quickly after breakthrough. Constant total liquid flow rate : This is the simplest variant in practise, especially when the wells are pumped. The oil flow rate decreases in time. Constant watercut : With a continuous decrease in the oil flow rate in time. This option can be used to optimize the cumulative oil produced. It is difficult to apply in practice, but it is the ideal variant. Production with decrease of the liquid flow rate in stages : This is an interesting combination, in practice, of the preceding two flow regimes. This regime consists of a succession of constant liquid flow ratestages with a decrease in the flow rate each time the fixed acceptable limit of the fw (or GOR is reached. The method proposed in this article is approximate because of the simplifying hypotheses introduced and because of :- the coning heights are calculated without taking the existence of perforations into consideration;- for high watercuts, the zero pressure-drop hypothesis in the aquifer has been retained, although it is not very realistic. The method has been checked, at least in the range between 1 and 10 to the power of 4 in adimensional time td, by comparison with :- production data,- laboratory experiments, - and numerical simulations. Data published for four wells [9, 10, 11

  3. SATSIM—A real-time multi-satellite simulator for test and validation in formation flying projects

    Science.gov (United States)

    Bodin, Per; Nylund, Matti; Battelino, Milan

    2012-05-01

    The satellite simulator SATSIM was developed during the experimental PRISMA multi-satellite formation flying project and was primarily aimed to validate the Guidance, Navigation and Control system (GNC) and the on-board software in a simulated real-time environment. The SATSIM system has as a main feature the ability to simulate sensors and actuators, spacecraft dynamics, intra-satellite communication protocols, environmental disturbances, solar illumination conditions as well as solar and lunar blinding. The core of the simulator consists of MATLAB/Simulink models of the spacecraft hardware and the space environment. The models run on a standard personal computer that in the simplest scenario may be connected to satellite controller boards through a CAN (Controller Area Network) data bus. SATSIM is, in conjunction with the RAMSES Test and Verification system, able to perform open-loop, hardware-in-the-loop as well as full-fledged closed-loop tests through the utilisation of peripheral sensor unit simulators. The PRISMA satellites were launched in June 2010 and the project is presently in its operational phase. This paper describes how a low cost but yet reliable simulator such as the SATSIM platform in different configurations has been used through the different phases of a multi-satellite project, from early test of onboard software running on satellite controller boards in a lab environment, to full-fledged closed-loop tests of satellite flight models.

  4. Detecting natural changes of cone-excitation ratios in simple and complex coloured images.

    Science.gov (United States)

    Nascimento, S M; Foster, D H

    1997-09-22

    Ratios of excitations in each cone-photoreceptor class produced by light reflected from pairs of surfaces in a scene are almost invariant under natural illuminant changes. The stability of these spatially defined ratios may explain the remarkable ability of human observers to efficiently discriminate illuminant changes from changes in surface reflectances. Spatial cone-excitation ratios are not, however, exactly invariant. This study is concerned with observers' sensitivity to these invariance violations. Simulations of Mondrian paintings with either 49 or two natural surfaces under Planckian illuminants were presented as images on a computer-controlled display in a two-interval experimental design: in one interval, the surfaces underwent an illuminant change; in the other interval, the surfaces underwent the same change but the images were then corrected so that, for each cone class, ratios of excitations were preserved exactly. Although the intervals with corrected images corresponded individually to highly improbable natural events, observers systematically misidentified them as containing the illuminant changes, the probability of error increasing as the violation of invariance in the other interval increased. For the range of illuminants and surfaces tested, sensitivity to violations of invariance was found to depend on cone class: it was greatest for long-wavelength-sensitive cones and least for short-wavelength-sensitive cones. Spatial cone-excitation ratios, or some closely related quantities, seem to be the cues preferred by observers for making inferences about surface illuminant changes.

  5. Development of carbon response trajectories using FIA plot data and FVS growth simulator: challenges of a large scale simulation project

    Science.gov (United States)

    James B. McCarter; Sean. Healey

    2015-01-01

    The Forest Carbon Management Framework (ForCaMF) integrates Forest Inventory and Analysis (FIA) plot inventory data, disturbance histories, and carbon response trajectories to develop estimates of disturbance and management effects on carbon pools for the National Forest System. All appropriate FIA inventory plots are simulated using the Forest Vegetation Simulator (...

  6. Topology of soft cone metric spaces

    Science.gov (United States)

    Altintas, Ismet; Simsek, Dagistan; Taskopru, Kemal

    2017-09-01

    In Simsek's paper it was introduced a concept of soft cone metric space via soft elements and some fixed point theorems in soft cone metric space were provided. In this work, we examine topological structures such as open ball, soft neighbourhood and soft open set in soft metric spaces and their some properties, and prove that every soft cone metric space under some condition is a soft topological space according to elementary operations on soft sets.

  7. Programming Retinal Stem Cells into Cone Photoreceptors

    Science.gov (United States)

    2015-12-01

    to program human stem cells directly into cones. Using RNA -seq, we identified several genes that are upregulated in advance of the earliest...reverse vision loss. 15. SUBJECT TERMS Cone photoreceptor, retina, retinal stem cell, Otx2, Onecut1, Blimp1, RNA -seq., transcription factors, and...sequential activation of OTX2, BLIMP1, and ONECUT1 are sufficient to program hES cell-derived retinal stem cells into transplant- competent cones

  8. G-weak contraction in ordered cone rectangular metric spaces.

    Science.gov (United States)

    Malhotra, S K; Sharma, J B; Shukla, Satish

    2013-01-01

    We prove some common fixed-point theorems for the ordered g-weak contractions in cone rectangular metric spaces without assuming the normality of cone. Our results generalize some recent results from cone metric and cone rectangular metric spaces into ordered cone rectangular metric spaces. Examples are provided which illustrate the results.

  9. g-Weak Contraction in Ordered Cone Rectangular Metric Spaces

    Directory of Open Access Journals (Sweden)

    S. K. Malhotra

    2013-01-01

    Full Text Available We prove some common fixed-point theorems for the ordered g-weak contractions in cone rectangular metric spaces without assuming the normality of cone. Our results generalize some recent results from cone metric and cone rectangular metric spaces into ordered cone rectangular metric spaces. Examples are provided which illustrate the results.

  10. Light-cones, almost light-cones and almost-complex light-cones

    Science.gov (United States)

    Newman, Ezra T.

    2017-08-01

    We point out (and then apply to a general situation) an unusual relationship among a variety of null geodesic congruences; (a) the generators of ordinary light-cones and (b) certain (related) shear-free but twisting congruences in Minkowski space-time as well as (c) asymptotically shear-free null geodesic congruences that exist in the neighborhood of Penrose's I^{ +} in Einstein or Einstein-Maxwell asymptotically flat-space-times. We refer to these geodesic congruences respectively as: Lignt-Cones (LCs), as "Almost-Complex"-Light-Cones (ACLCs), [though they are real they resemble complex light-cones in complex Minkowski space] and finally to a family of congruences in asymptotically flat-spaces as ` Almost Light-Cones' (ALC). The two essential points of resemblance among the three families are: (1) they are all either shear-free or asymptotically shear-free and (2) in each family the individual members of the family can be labeled by the points in a real or complex four-dimensional manifold. As an example, the Minkowski space LCs are labeled by the (real) coordinate value of their apex. In the case of (ACLCs) (complex coordinate values), the congruences will have non-vanishing twist whose magnitude is determined by the imaginary part of the complex coordinate values. In studies of gravitational radiation, Bondi-type of null surfaces and their associated Bondi coordinates have been almost exclusively used for calculations. It turns out that some surprising relations arise if, instead of the Bondi coordinates, one uses ALCs and their associated coordinate systems in the analysis of the Einstein-Maxwell equations in the neighborhood of I+. More explicitly and surprisingly, the asymptotic Bianchi Identities (arising directly from the Einstein equations), expressed in the coordinates of the ALCs, turn directly into many of the standard definitions and equations and relations of classical mechanics coupled with Maxwell's equations. These results extend and generalize the

  11. UAS in the NAS Project: Large-Scale Communication Architecture Simulations with NASA GRC Gen5 Radio Model

    Science.gov (United States)

    Kubat, Gregory

    2016-01-01

    This report provides a description and performance characterization of the large-scale, Relay architecture, UAS communications simulation capability developed for the NASA GRC, UAS in the NAS Project. The system uses a validated model of the GRC Gen5 CNPC, Flight-Test Radio model. Contained in the report is a description of the simulation system and its model components, recent changes made to the system to improve performance, descriptions and objectives of sample simulations used for test and verification, and a sampling and observations of results and performance data.

  12. 3D algebraic iterative reconstruction for cone-beam x-ray differential phase-contrast computed tomography.

    Directory of Open Access Journals (Sweden)

    Jian Fu

    Full Text Available Due to the potential of compact imaging systems with magnified spatial resolution and contrast, cone-beam x-ray differential phase-contrast computed tomography (DPC-CT has attracted significant interest. The current proposed FDK reconstruction algorithm with the Hilbert imaginary filter will induce severe cone-beam artifacts when the cone-beam angle becomes large. In this paper, we propose an algebraic iterative reconstruction (AIR method for cone-beam DPC-CT and report its experiment results. This approach considers the reconstruction process as the optimization of a discrete representation of the object function to satisfy a system of equations that describes the cone-beam DPC-CT imaging modality. Unlike the conventional iterative algorithms for absorption-based CT, it involves the derivative operation to the forward projections of the reconstructed intermediate image to take into account the differential nature of the DPC projections. This method is based on the algebraic reconstruction technique, reconstructs the image ray by ray, and is expected to provide better derivative estimates in iterations. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a mini-focus x-ray tube source. It is shown that the proposed method can reduce the cone-beam artifacts and performs better than FDK under large cone-beam angles. This algorithm is of interest for future cone-beam DPC-CT applications.

  13. Design, Results, Evolution and Status of the ATLAS Simulation at Point1 Project

    Science.gov (United States)

    Ballestrero, S.; Batraneanu, S. M.; Brasolin, F.; Contescu, C.; Fazio, D.; Di Girolamo, A.; Lee, C. J.; Pozo Astigarraga, M. E.; Scannicchio, D. A.; Sedov, A.; Twomey, M. S.; Wang, F.; Zaytsev, A.

    2015-12-01

    During the LHC Long Shutdown 1 (LSI) period, that started in 2013, the Simulation at Point1 (Sim@P1) project takes advantage, in an opportunistic way, of the TDAQ (Trigger and Data Acquisition) HLT (High-Level Trigger) farm of the ATLAS experiment. This farm provides more than 1300 compute nodes, which are particularly suited for running event generation and Monte Carlo production jobs that are mostly CPU and not I/O bound. It is capable of running up to 2700 Virtual Machines (VMs) each with 8 CPU cores, for a total of up to 22000 parallel jobs. This contribution gives a review of the design, the results, and the evolution of the Sim@P1 project, operating a large scale OpenStack based virtualized platform deployed on top of the ATLAS TDAQ HLT farm computing resources. During LS1, Sim@P1 was one of the most productive ATLAS sites: it delivered more than 33 million CPU-hours and it generated more than 1.1 billion Monte Carlo events. The design aspects are presented: the virtualization platform exploited by Sim@P1 avoids interferences with TDAQ operations and it guarantees the security and the usability of the ATLAS private network. The cloud mechanism allows the separation of the needed support on both infrastructural (hardware, virtualization layer) and logical (Grid site support) levels. This paper focuses on the operational aspects of such a large system during the upcoming LHC Run 2 period: simple, reliable, and efficient tools are needed to quickly switch from Sim@P1 to TDAQ mode and back, to exploit the resources when they are not used for the data acquisition, even for short periods. The evolution of the central OpenStack infrastructure is described, as it was upgraded from Folsom to the Icehouse release, including the scalability issues addressed.

  14. Ionic emission from Taylor cones

    Science.gov (United States)

    Castro Reina, Sergio

    Electrified Taylor cones have been seen as an efficient way to generate thrust for space propulsion. Especially the pure ionic regime (PIR) combines a very high specific impulse (thrust per unit mass) and efficiency, which is very important to reduce fuel transportation costs. The PIR has been primarily based on electrosprays of liquid metals [Swatik and Hendricks 1968, Swatik 1969]. However, emissions dominated by or containing exclusively ions have also been observed from nonmetallic purely ionic substances, initially sulfuric acid [Perel et al. 1969], and more recently room temperature molten salts referred to as ionic liquids (ILs) [Romero-Sanz et al. 2003]. The recent use of the liquid metal ion source (LMIS) with ILs, becoming this "new" source to be known as ionic liquid ion source (ILIS) [Lozano and Martinez-Sanchez 2005], has shown important differences on the emission from Taylor cones with the traditional hollow capillary. This new source seems to be more flexible than the capillary [Paulo, Sergio, carlos], although its low emission level (low thrust) is an important drawback from the space propulsion point of view. Throughout the thesis I have studied some aspects of the ionic emission from ionic liquid Taylor cones and the influence of the properties of the liquids and the characteristic of source on the emission. I have unraveled the reason why ILIS emits such low currents (˜200 nA) and found a way to solve this problem increasing the current up to capillary levels (˜1000 nA) [Castro and Fernandez de la Mora 2009]. I have also tried to reduce ion evaporation while reducing the emitted droplet size in order to increase the thrust generated while keeping the efficiency relatively high and I have measured the energy of evaporation of several cations composing ionic liquids, mandatory step to understand ionic evaporation.

  15. A High Performance Chemical Simulation Preprocessor and Source Code Generator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Numerical simulations of chemical kinetics are a critical component of aerospace research, Earth systems research, and energy research. These simulations enable a...

  16. Hypersonic Control Modeling and Simulation Tool for Lifting Towed Ballutes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Aerospace Corporation proposes to develop a hypersonic control modeling and simulation tool for hypersonic aeroassist vehicles. Our control and simulation...

  17. Advanced Unsteady Turbulent Combustion Simulation Capability for Space Propulsion Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation proposed here is a high performance, high fidelity simulation capability to enable accurate, fast and robust simulation of unsteady turbulent,...

  18. Low-cost, High Titanium Mare Simulant: Bulk, Dust and "Orange Spheres" Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Space exploration require simulants for equipment design, development and testing. This proposal directly responds to the solicitation by improving simulant...

  19. Growth cone travel in space and time: the cellular ensemble of cytoskeleton, adhesion, and membrane.

    Science.gov (United States)

    Vitriol, Eric A; Zheng, James Q

    2012-03-22

    Growth cones, found at the tip of axonal projections, are the sensory and motile organelles of developing neurons that enable axon pathfinding and target recognition for precise wiring of the neural circuitry. To date, many families of conserved guidance molecules and their corresponding receptors have been identified that work in space and time to ensure billions of axons to reach their targets. Research in the past two decades has also gained significant insight into the ways in which growth cones translate extracellular signals into directional migration. This review aims to examine new progress toward understanding the cellular mechanisms underlying directional motility of the growth cone and to discuss questions that remain to be addressed. Specifically, we will focus on the cellular ensemble of cytoskeleton, adhesion, and membrane and examine how the intricate interplay between these processes orchestrates the directed movement of growth cones. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Global drought in the 20th and 21st centuries : analysis of retrospective simulations and future projections of soil moisture

    NARCIS (Netherlands)

    Sheffield, J.

    2008-01-01

    We describe the analysis of global and regional drought over the second half of the 20th century from a retrospective model simulation of the terrestrial water cycle, and projected 21st century changes using multi-scenario data from multiple climate models. A global meteorological forcing dataset is

  1. Revised Comparisons of Simulated Hydrodynamics and Water Quality for Projected Demands in 2046, Pueblo Reservoir, Southeastern Colorado

    Science.gov (United States)

    Ortiz, Roderick F.; Miller, Lisa D.

    2009-01-01

    Pueblo Reservoir is one of southeastern Colorado's most valuable water resources. The reservoir provides irrigation, municipal, and industrial water to various entities throughout the region. The reservoir also provides flood control, recreational activities, sport fishing, and wildlife enhancement to the region. The Southern Delivery System (SDS) project is a regional water-delivery project that has been proposed to provide a safe, reliable, and sustainable water supply through the foreseeable future (2046) for Colorado Springs, Fountain, Security, and Pueblo West. Discussions with the Bureau of Reclamation and the U.S. Geological Survey led to a cooperative agreement to simulate the hydrodynamics and water quality of Pueblo Reservoir. This work has been completed and described in a previously published report, U.S. Geological Survey Scientific Investigations Report 2008-5056. Additionally, there was a need to make comparisons of simulated hydrodynamics and water quality for projected demands associated with the various Environmental Impact Statements (EIS) alternatives and plans by Pueblo West to discharge treated wastewater into the reservoir. Wastewater plans by Pueblo West are fully independent of the SDS project. This report compares simulated hydrodynamics and water quality for projected demands in Pueblo Reservoir resulting from changes in inflow and water quality entering the reservoir, and from changes to withdrawals from the reservoir as projected for the year 2046. Four of the seven EIS alternatives were selected for scenario simulations. The four U.S. Geological Survey simulation scenarios were the No Action scenario (EIS Alternative 1), the Downstream Diversion scenario (EIS Alternative 2), the Upstream Return-Flow scenario (EIS Alternative 4), and the Upstream Diversion scenario (EIS Alternative 7). Additionally, the results of an Existing Conditions scenario (year 2006 demand conditions) were compared to the No Action scenario (projected demands in

  2. Using an ensemble of climate projections for simulating recent and near-future hydrological change to lake Vaenern in Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Jonas; Yang, Wei; Graham, L. Phil; Rosberg, Joergen; Andreasson, Johan (Swedish Meteorological and Hydrological Inst., Norrkoeping (Sweden)), e-mail: jonas.olsson@smhi.se

    2011-01-15

    Lake Vaenern and River Goeta aelv in southern Sweden constitute a large and complex hydrological system that is highly vulnerable to climate change. In this study, an ensemble of 12 regional climate projections is used to simulate the inflow to Lake Vaenern by the HBV hydrological model. By using distribution based scaling of the climate model output, all projections can accurately reproduce the annual cycle of mean monthly inflows for the period 1961-1990 as simulated using HBV with observed temperature and precipitation ('HBVobs'). Significant changes towards higher winter inflow and a reduced spring flood were found when comparing the period 1991-2008 to 1961-1990 in the HBVobs simulations and the ability of the regional projections to reproduce these changes varied. The main uncertainties in the projections for 1991-2008 were found to originate from the global climate model used, including its initialization, and in one case, the emissions scenario, whereas the regional climate model used and its resolution showed a smaller influence. The projections that most accurately reproduce the recent change suggest that the current trends in the winter and spring inflows will continue over the period 2009-2030

  3. Enhanced proton acceleration by intense laser interaction with an inverse cone target

    Energy Technology Data Exchange (ETDEWEB)

    Bake, Muhammad Ali; Aimidula, Aimierding, E-mail: amir@mail.bnu.edu.cn; Xiaerding, Fuerkaiti; Rashidin, Reyima [School of Physics Science and Technology, Xinjiang University, Urumqi 830046 (China)

    2016-08-15

    The generation and control of high-quality proton bunches using focused intense laser pulse on an inverse cone target is investigated with a set of particle-in-cell simulations. The inverse cone is a high atomic number conical frustum with a thin solid top and open base, where the laser impinges onto the top surface directly, not down the open end of the cone. Results are compared with a simple planar target, where the proton angular distribution is very broad because of transverse divergence of the electromagnetic fields behind the target. For a conical target, hot electrons along the cone wall surface induce a transverse focusing sheath field. This field can effectively suppress the spatial spreading of the protons, resulting in a high-quality small-emittance, low-divergence proton beam. A slightly lower proton beam peak energy than that of a conventional planar target was also found.

  4. Interplay between Mach cone and radial expansion in jet events

    Energy Technology Data Exchange (ETDEWEB)

    Tachibana, Y., E-mail: tachibana@nt.phys.s.u-tokyo.ac.jp [Theoretical Research Division, Nishina Center, RIKEN, Wako 351-0198 (Japan); Department of Engineering, Nishinippon Institute of Technology, Fukuoka 800-0344 (Japan); Department of Physics, Sophia University, Tokyo 102-8554 (Japan); Hirano, T., E-mail: hirano@sophia.ac.jp [Department of Physics, Sophia University, Tokyo 102-8554 (Japan)

    2016-12-15

    We study the hydrodynamic response to jet propagation in the expanding QGP and investigate how the particle spectra after the hydrodynamic evolution of the QGP reflect it. We perform simulations of the space-time evolution of the QGP in gamma-jet events by solving (3+1)-dimensional ideal hydrodynamic equations with source terms. Mach cone is induced by the jet energy deposition and pushes back the radial flow of the expanding background. Especially in the case when the jet passage is off-central one, the number of particles emitted in the direction of the push back decreases. This is the signal including the information about the formation of the Mach cone and the jet passage in the QGP fluid.

  5. COMPASS, the COMmunity Petascale Project for Accelerator Science and Simulation, a broad computational accelerator physics initiative

    Energy Technology Data Exchange (ETDEWEB)

    J.R. Cary; P. Spentzouris; J. Amundson; L. McInnes; M. Borland; B. Mustapha; B. Norris; P. Ostroumov; Y. Wang; W. Fischer; A. Fedotov; I. Ben-Zvi; R. Ryne; E. Esarey; C. Geddes; J. Qiang; E. Ng; S. Li; C. Ng; R. Lee; L. Merminga; H. Wang; D.L. Bruhwiler; D. Dechow; P. Mullowney; P. Messmer; C. Nieter; S. Ovtchinnikov; K. Paul; P. Stoltz; D. Wade-Stein; W.B. Mori; V. Decyk; C.K. Huang; W. Lu; M. Tzoufras; F. Tsung; M. Zhou; G.R. Werner; T. Antonsen; T. Katsouleas

    2007-06-01

    Accelerators are the largest and most costly scientific instruments of the Department of Energy, with uses across a broad range of science, including colliders for particle physics and nuclear science and light sources and neutron sources for materials studies. COMPASS, the Community Petascale Project for Accelerator Science and Simulation, is a broad, four-office (HEP, NP, BES, ASCR) effort to develop computational tools for the prediction and performance enhancement of accelerators. The tools being developed can be used to predict the dynamics of beams in the presence of optical elements and space charge forces, the calculation of electromagnetic modes and wake fields of cavities, the cooling induced by comoving beams, and the acceleration of beams by intense fields in plasmas generated by beams or lasers. In SciDAC-1, the computational tools had multiple successes in predicting the dynamics of beams and beam generation. In SciDAC-2 these tools will be petascale enabled to allow the inclusion of an unprecedented level of physics for detailed prediction.

  6. COMPASS, the COMmunity Petascale project for Accelerator Science and Simulation, a board computational accelerator physics initiative

    Energy Technology Data Exchange (ETDEWEB)

    Cary, J.R.; Spentzouris, P.; Amundson, J.; McInnes, L.; Borland, M.; Mustapha, B.; Ostroumov, P.; Wang, Y.; Fischer, W.; Fedotov, A.; Ben-Zvi, I.; Ryne, R.; Esarey, E.; Geddes, C.; Qiang, J.; Ng, E.; Li, S.; Ng, C.; Lee, R.; Merminga, L.; Wang, H.; Bruhwiler, D.L.; Dechow, D.; Mullowney, P.; Messmer, P.; Nieter, C.; Ovtchinnikov, S.; Paul, K.; Stoltz, P.; Wade-Stein, D.; Mori, W.B.; Decyk, V.; Huang, C.K.; Lu, W.; Tzoufras, M.; Tsung, F.; Zhou, M.; Werner, G.R.; Antonsen, T.; Katsouleas, T.; Morris, B.

    2007-07-16

    Accelerators are the largest and most costly scientific instruments of the Department of Energy, with uses across a broad range of science, including colliders for particle physics and nuclear science and light sources and neutron sources for materials studies. COMPASS, the Community Petascale Project for Accelerator Science and Simulation, is a broad, four-office (HEP, NP, BES, ASCR) effort to develop computational tools for the prediction and performance enhancement of accelerators. The tools being developed can be used to predict the dynamics of beams in the presence of optical elements and space charge forces, the calculation of electromagnetic modes and wake fields of cavities, the cooling induced by comoving beams, and the acceleration of beams by intense fields in plasmas generated by beams or lasers. In SciDAC-1, the computational tools had multiple successes in predicting the dynamics of beams and beam generation. In SciDAC-2 these tools will be petascale enabled to allow the inclusion of an unprecedented level of physics for detailed prediction.

  7. Comparison of Ice-Bank Actual Results Against Simulated Predicted Results in Carroll Refurbishment Project DKIT

    Directory of Open Access Journals (Sweden)

    Edel Donnelly

    2012-11-01

    Full Text Available This paper reviews the selection methods used in the design of an ice-bank thermal energy storage (TES application in the Carroll’s building in Dundalk IT. The complexities of the interaction between the on- site wind turbine, existing campus load and the refurbished building meant that traditional calculation methods and programmes could not be used and specialist software had to be developed during the design process. The research reviews this tool against the actual results obtained from the operation in the building for one college term of full time use. The paper also examines the operation of the system in order to produce recommendations for its potential modification to improve its efficiency and utilisation. Simulation software is evaluated and maximum import capacity is minimised. Significant budget constraints limited the level of control and metering that could be provided for the project, and this paper demonstrates some investigative processes that were used to overcome the limitations on data availability.

  8. Development studies for the ILC: Measurements and simulations for a time projection chamber with GEM technology

    Science.gov (United States)

    Ledermann, Bernhard; Kaminski, Jochen; Kappler, Steffen; Müller, Thomas

    2007-10-01

    A Time Projection Chamber (TPC) with Gas Electron Multiplier (GEM) technology is well suited for usage as central tracker at the International Linear Collider (ILC). To study the high potential of this detector type a small prototype of 25 cm length was built in Karlsruhe and used in several experimental setups. In this publication the results of these measurements and of additional Monte Carlo simulations are presented. By introducing the so-called equivalent drift distance a combination of all results was possible leading to a recommended configuration of the multi-GEM tower for the ILC-TPC. It will be shown that for conditions considered in the TESLA-TDR the transverse spatial resolution will be able to reach 65 μm for 10 cm and 190 μm for 200 cm drift at the ILC. This as well as the expectations for longitudinal spatial resolution, for energy resolutions of the specific ionization, and for single pad row efficiency should be able to meet the requirements of a future ILC-TPC.

  9. Evaluation of Arctic Sea Ice Thickness Simulated by Arctic Ocean Model Intercomparison Project Models

    Science.gov (United States)

    Johnson, Mark; Proshuntinsky, Andrew; Aksenov, Yevgeny; Nguyen, An T.; Lindsay, Ron; Haas, Christian; Zhang, Jinlun; Diansky, Nikolay; Kwok, Ron; Maslowski, Wieslaw; hide

    2012-01-01

    Six Arctic Ocean Model Intercomparison Project model simulations are compared with estimates of sea ice thickness derived from pan-Arctic satellite freeboard measurements (2004-2008); airborne electromagnetic measurements (2001-2009); ice draft data from moored instruments in Fram Strait, the Greenland Sea, and the Beaufort Sea (1992-2008) and from submarines (1975-2000); and drill hole data from the Arctic basin, Laptev, and East Siberian marginal seas (1982-1986) and coastal stations (1998-2009). Despite an assessment of six models that differ in numerical methods, resolution, domain, forcing, and boundary conditions, the models generally overestimate the thickness of measured ice thinner than approximately 2 mand underestimate the thickness of ice measured thicker than about approximately 2m. In the regions of flat immobile landfast ice (shallow Siberian Seas with depths less than 25-30 m), the models generally overestimate both the total observed sea ice thickness and rates of September and October ice growth from observations by more than 4 times and more than one standard deviation, respectively. The models do not reproduce conditions of fast ice formation and growth. Instead, the modeled fast ice is replaced with pack ice which drifts, generating ridges of increasing ice thickness, in addition to thermodynamic ice growth. Considering all observational data sets, the better correlations and smaller differences from observations are from the Estimating the Circulation and Climate of the Ocean, Phase II and Pan-Arctic Ice Ocean Modeling and Assimilation System models.

  10. Ocean response to volcanic eruptions in Coupled Model Intercomparison Project 5 simulations

    KAUST Repository

    Ding, Yanni

    2014-09-01

    We examine the oceanic impact of large tropical volcanic eruptions as they appear in ensembles of historical simulations from eight Coupled Model Intercomparison Project Phase 5 models. These models show a response that includes lowering of global average sea surface temperature by 0.1–0.3 K, comparable to the observations. They show enhancement of Arctic ice cover in the years following major volcanic eruptions, with long-lived temperature anomalies extending to the middepth and deep ocean on decadal to centennial timescales. Regional ocean responses vary, although there is some consistent hemispheric asymmetry associated with the hemisphere in which the eruption occurs. Temperature decreases and salinity increases contribute to an increase in the density of surface water and an enhancement in the overturning circulation of the North Atlantic Ocean following these eruptions. The strength of this overturning increase varies considerably from model to model and is correlated with the background variability of overturning in each model. Any cause/effect relationship between eruptions and the phase of El Niño is weak.

  11. Comparison of projection skills of deterministic ensemble methods using pseudo-simulation data generated from multivariate Gaussian distribution

    Science.gov (United States)

    Oh, Seok-Geun; Suh, Myoung-Seok

    2017-07-01

    The projection skills of five ensemble methods were analyzed according to simulation skills, training period, and ensemble members, using 198 sets of pseudo-simulation data (PSD) produced by random number generation assuming the simulated temperature of regional climate models. The PSD sets were classified into 18 categories according to the relative magnitude of bias, variance ratio, and correlation coefficient, where each category had 11 sets (including 1 truth set) with 50 samples. The ensemble methods used were as follows: equal weighted averaging without bias correction (EWA_NBC), EWA with bias correction (EWA_WBC), weighted ensemble averaging based on root mean square errors and correlation (WEA_RAC), WEA based on the Taylor score (WEA_Tay), and multivariate linear regression (Mul_Reg). The projection skills of the ensemble methods improved generally as compared with the best member for each category. However, their projection skills are significantly affected by the simulation skills of the ensemble member. The weighted ensemble methods showed better projection skills than non-weighted methods, in particular, for the PSD categories having systematic biases and various correlation coefficients. The EWA_NBC showed considerably lower projection skills than the other methods, in particular, for the PSD categories with systematic biases. Although Mul_Reg showed relatively good skills, it showed strong sensitivity to the PSD categories, training periods, and number of members. On the other hand, the WEA_Tay and WEA_RAC showed relatively superior skills in both the accuracy and reliability for all the sensitivity experiments. This indicates that WEA_Tay and WEA_RAC are applicable even for simulation data with systematic biases, a short training period, and a small number of ensemble members.

  12. Implementation of Lean Engineering Practices in Projects and Programs through Simulation Based Training

    DEFF Research Database (Denmark)

    Shtub, Avraham; Iluz, Michal; Gersing, Kilian

    2014-01-01

    Teams in engineering projects face complex decisions on a daily basis. In order to meet or exceed stakeholders’ needs and expectations project teams must plan and re-plan their project to keep it on track. Their decisions are made in an uncertain, dynamic and constrained environment spanning a la...... project team members and stakeholders in two different industries in order to lead to better project outcomes in terms of time, performance, cost, and stakeholders’ approval....

  13. Simulations

    CERN Document Server

    Ngada, Narcisse

    2015-06-15

    The complexity and cost of building and running high-power electrical systems make the use of simulations unavoidable. The simulations available today provide great understanding about how systems really operate. This paper helps the reader to gain an insight into simulation in the field of power converters for particle accelerators. Starting with the definition and basic principles of simulation, two simulation types, as well as their leading tools, are presented: analog and numerical simulations. Some practical applications of each simulation type are also considered. The final conclusion then summarizes the main important items to keep in mind before opting for a simulation tool or before performing a simulation.

  14. A Method to Improve Electron Density Measurement of Cone-Beam CT Using Dual Energy Technique

    Directory of Open Access Journals (Sweden)

    Kuo Men

    2015-01-01

    Full Text Available Purpose. To develop a dual energy imaging method to improve the accuracy of electron density measurement with a cone-beam CT (CBCT device. Materials and Methods. The imaging system is the XVI CBCT system on Elekta Synergy linac. Projection data were acquired with the high and low energy X-ray, respectively, to set up a basis material decomposition model. Virtual phantom simulation and phantoms experiments were carried out for quantitative evaluation of the method. Phantoms were also scanned twice with the high and low energy X-ray, respectively. The data were decomposed into projections of the two basis material coefficients according to the model set up earlier. The two sets of decomposed projections were used to reconstruct CBCT images of the basis material coefficients. Then, the images of electron densities were calculated with these CBCT images. Results. The difference between the calculated and theoretical values was within 2% and the correlation coefficient of them was about 1.0. The dual energy imaging method obtained more accurate electron density values and reduced the beam hardening artifacts obviously. Conclusion. A novel dual energy CBCT imaging method to calculate the electron densities was developed. It can acquire more accurate values and provide a platform potentially for dose calculation.

  15. Interior points of the completely positive cone.

    NARCIS (Netherlands)

    Dür, Mirjam; Still, Georg J.

    2008-01-01

    A matrix A is called completely positive if it can be decomposed as A = BB^T with an entrywise nonnegative matrix B. The set of all such matrices is a convex cone. We provide a characterization of the interior of this cone as well as of its dual.

  16. A Practical Seedless Infrared Safe Cone Algorithm

    OpenAIRE

    Salam, Gavin P.

    2007-01-01

    This writeup highlights the infrared unsafety of the "midpoint" cone jet-algorithm and provides a brief overview of why this is a serious issue. It then shows how one can build a safe (seedless) cone algorithm and discusses the potential impact on measurements.

  17. Cone calorimeter tests of wood composites

    Science.gov (United States)

    Robert H. White; Kuma Sumathipala

    2013-01-01

    The cone calorimeter is widely used for the determination of the heat release rate (HRR) of building products and other materials. As part of an effort to increase the availability of cone calorimeter data on wood products, the U.S. Forest Products Laboratory and the American Wood Council conducted this study on composite wood products in cooperation with the Composite...

  18. Double Dirac cones in phononic crystals

    KAUST Repository

    Li, Yan

    2014-07-07

    A double Dirac cone is realized at the center of the Brillouin zone of a two-dimensional phononic crystal (PC) consisting of a triangular array of core-shell-structure cylinders in water. The double Dirac cone is induced by the accidental degeneracy of two double-degenerate Bloch states. Using a perturbation method, we demonstrate that the double Dirac cone is composed of two identical and overlapping Dirac cones whose linear slopes can also be accurately predicted from the method. Because the double Dirac cone occurs at a relatively low frequency, a slab of the PC can be mapped onto a slab of zero refractive index material by using a standard retrieval method. Total transmission without phase change and energy tunneling at the double Dirac point frequency are unambiguously demonstrated by two examples. Potential applications can be expected in diverse fields such as acoustic wave manipulations and energy flow control.

  19. Mechanochemical regulation of growth cone motility

    Directory of Open Access Journals (Sweden)

    Patrick C Kerstein

    2015-07-01

    Full Text Available Neuronal growth cones are exquisite sensory-motor machines capable of transducing features contacted in their local extracellular environment into guided process extension during development. Extensive research has shown that chemical ligands activate cell surface receptors on growth cones leading to intracellular signals that direct cytoskeletal changes. However, the environment also provides mechanical support for growth cone adhesion and traction forces that stabilize leading edge protrusions. Interestingly, recent work suggests that both the mechanical properties of the environment and mechanical forces generated within growth cones influence axon guidance. In this review we discuss novel molecular mechanisms involved in growth cone force production and detection, and speculate how these processes may be necessary for the development of proper neuronal morphogenesis.

  20. Fusion Simulation Project. Workshop Sponsored by the U.S. Department of Energy, Rockville, MD, May 16-18, 2007

    Energy Technology Data Exchange (ETDEWEB)

    Kritz, A.; Keyes, D.

    2007-05-18

    The mission of the Fusion Simulation Project is to develop a predictive capability for the integrated modeling of magnetically confined plasmas. This FSP report adds to the previous activities that defined an approach to integrated modeling in magnetic fusion. These previous activities included a Fusion Energy Sciences Advisory Committee panel that was charged to study integrated simulation in 2002. The report of that panel [Journal of Fusion Energy 20, 135 (2001)] recommended the prompt initiation of a Fusion Simulation Project. In 2003, the Office of Fusion Energy Sciences formed a steering committee that developed a project vision, roadmap, and governance concepts [Journal of Fusion Energy 23, 1 (2004)]. The current FSP planning effort involved forty-six physicists, applied mathematicians and computer scientists, from twenty-one institutions, formed into four panels and a coordinating committee. These panels were constituted to consider: Status of Physics Components, Required Computational and Applied Mathematics Tools, Integration and Management of Code Components, and Project Structure and Management. The ideas, reported here, are the products of these panels, working together over several months and culminating in a three-day workshop in May 2007.

  1. Fusion Simulation Project. Workshop sponsored by the U.S. Department of Energy Rockville, MD, May 16-18, 2007

    Energy Technology Data Exchange (ETDEWEB)

    None

    2007-05-16

    The mission of the Fusion Simulation Project is to develop a predictive capability for the integrated modeling of magnetically confined plasmas. This FSP report adds to the previous activities that defined an approach to integrated modeling in magnetic fusion. These previous activities included a Fusion Energy Sciences Advisory Committee panel that was charged to study integrated simulation in 2002. The report of that panel [Journal of Fusion Energy 20, 135 (2001)] recommended the prompt initiation of a Fusion Simulation Project. In 2003, the Office of Fusion Energy Sciences formed a steering committee that developed a project vision, roadmap, and governance concepts [Journal of Fusion Energy 23, 1 (2004)]. The current FSP planning effort involved forty-six physicists, applied mathematicians and computer scientists, from twenty-one institutions, formed into four panels and a coordinating committee. These panels were constituted to consider: Status of Physics Components, Required Computational and Applied Mathematics Tools, Integration and Management of Code Components, and Project Structure and Management. The ideas, reported here, are the products of these panels, working together over several months and culminating in a three-day workshop in May 2007.

  2. Characterization of Scattered X-Ray Photons in Dental Cone-Beam Computed Tomography.

    Directory of Open Access Journals (Sweden)

    Ching-Ching Yang

    Full Text Available Scatter is a very important artifact causing factor in dental cone-beam CT (CBCT, which has a major influence on the detectability of details within images. This work aimed to improve the image quality of dental CBCT through scatter correction.Scatter was estimated in the projection domain from the low frequency component of the difference between the raw CBCT projection and the projection obtained by extrapolating the model fitted to the raw projections acquired with 2 different sizes of axial field-of-view (FOV. The function for curve fitting was optimized by using Monte Carlo simulation. To validate the proposed method, an anthropomorphic phantom and a water-filled cylindrical phantom with rod inserts simulating different tissue materials were scanned using 120 kVp, 5 mA and 9-second scanning time covering an axial FOV of 4 cm and 13 cm. The detectability of the CT image was evaluated by calculating the contrast-to-noise ratio (CNR.Beam hardening and cupping artifacts were observed in CBCT images without scatter correction, especially in those acquired with 13 cm FOV. These artifacts were reduced in CBCT images corrected by the proposed method, demonstrating its efficacy on scatter correction. After scatter correction, the image quality of CBCT was improved in terms of target detectability which was quantified as the CNR for rod inserts in the cylindrical phantom.Hopefully the calculations performed in this work can provide a route to reach a high level of diagnostic image quality for CBCT imaging used in oral and maxillofacial structures whilst ensuring patient dose as low as reasonably achievable, which may ultimately make CBCT scan a reliable and safe tool in clinical practice.

  3. Characterization of Scattered X-Ray Photons in Dental Cone-Beam Computed Tomography.

    Science.gov (United States)

    Yang, Ching-Ching

    2016-01-01

    Scatter is a very important artifact causing factor in dental cone-beam CT (CBCT), which has a major influence on the detectability of details within images. This work aimed to improve the image quality of dental CBCT through scatter correction. Scatter was estimated in the projection domain from the low frequency component of the difference between the raw CBCT projection and the projection obtained by extrapolating the model fitted to the raw projections acquired with 2 different sizes of axial field-of-view (FOV). The function for curve fitting was optimized by using Monte Carlo simulation. To validate the proposed method, an anthropomorphic phantom and a water-filled cylindrical phantom with rod inserts simulating different tissue materials were scanned using 120 kVp, 5 mA and 9-second scanning time covering an axial FOV of 4 cm and 13 cm. The detectability of the CT image was evaluated by calculating the contrast-to-noise ratio (CNR). Beam hardening and cupping artifacts were observed in CBCT images without scatter correction, especially in those acquired with 13 cm FOV. These artifacts were reduced in CBCT images corrected by the proposed method, demonstrating its efficacy on scatter correction. After scatter correction, the image quality of CBCT was improved in terms of target detectability which was quantified as the CNR for rod inserts in the cylindrical phantom. Hopefully the calculations performed in this work can provide a route to reach a high level of diagnostic image quality for CBCT imaging used in oral and maxillofacial structures whilst ensuring patient dose as low as reasonably achievable, which may ultimately make CBCT scan a reliable and safe tool in clinical practice.

  4. A Renewed Approach for Large Eddy Simulation of Complex Geometries Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The potential benefits of Large Eddy Simulation (LES) for aerodynamics and combustion simulation hvae largely been missed, due to the complexity of generating grids...

  5. Resin Transfer Moulding Of An Engine Thrust Frame Cone Cap

    Science.gov (United States)

    Brodsjo, Anders; Fatemi, Javad; de Vries, Henri

    2012-07-01

    For the Ariane 5 Midlife Evolution, a new Engine Thrust Frame for the upper stage is being developed. Part of this Engine Thrust Frame is the so-called Cone Cap, which closes the inverted cone shape of the structure. This part is highly loaded, as it transfers all the loads from the engines to the cone shape, and includes the hinge points for the mechanism that steer the engines. Besides strength to cope with the loads, stiffness is a very important design parameter. A composite design of this structure has been developed, which is approximately 15 kg’s lighter than the aluminium structure. To manufacture such a part in composites is challenging, because of the complexity of the shape and large laminate thickness. Due to these requirements, Resin Transfer Moulding has been selected as manufacturing method, which allows this highly integrated structure to be made in one step. As part of this project, a quarter segment of the full-scale design has been manufactured. From the design model, a detailed design for the dry fibre preform has been made using advanced composite laminate software tools. This preform was placed inside a heated, double sided tool and injected with the resin.

  6. Impact of a Liquid Cone on a Plain Rigid Wall

    Directory of Open Access Journals (Sweden)

    A.A. Aganin

    2016-03-01

    Full Text Available A numerical study of high-speed (with the velocity of 250 m/s impact of a liquid cone (cone-like jet on a plain rigid wall has been performed. The range of the angles of inclination of the cone surface to the wall corresponds to that of their variation in the process of impact on the wall of a cylindrical jet with the semi-spherical end. The direct numerical simulation has been used on the basis of the gas dynamics equations by the CIP-CUP method on the dynamically adaptive Soroban-grids without explicit tracking of the interphase boundary. It has been found that three regimes of impact are set in the examined range of the angles. At the small angles the impact with shock wave attached to the wall without liquid spreading is realized. An abrupt transition to the regime with the shock wave detached from the wall together with the radial jet of the liquid spreading on the wall takes place with increasing the angle. A smooth transition to the shockless regime with the radial liquid jet is realized with further increasing the angle.

  7. Reducing dislocation density in GaN films using a cone-shaped patterned sapphire substrate

    Science.gov (United States)

    Shin, Hui-Youn; Kwon, S. K.; Chang, Y. I.; Cho, M. J.; Park, K. H.

    2009-08-01

    The threading dislocation (TD) density in GaN films grown directly on flat sapphire substrates is typically >10 10/cm 2, which can deteriorate the properties of GaN-based LEDs significantly. This paper reports an approach to reducing the TD density in a GaN layer using a variety of patterned sapphire substrates (PSS). A cone-shaped PSS produced by metal organic chemical vapor deposition (MOVCD) was used for GaN deposition. Three types of GaN specimens were prepared at the initial nucleation stage, middle growth stage and final growth stage. The TDs generated on the cone-shaped PSS were analyzed by transmission electron microscopy (TEM) and a strain mapping simulation using HRTEM images, which evaluated the residual strain distribution. A large number of TDs were generated and the residual strain by the lattice distortions remained above the top of the cone-shaped regions. However, no TDs and residual strain were observed at the slope of the cone-shaped regions. This might be due to the formation of a GaN layer by lateral overgrowth at the slope of the cone-shaped regions, resulting in less lattice mismatch and incoherency between the GaN and sapphire. In conclusion, the TD density in the GaN layer could be reduced significantly, approximately 10 7/cm 2, using the cone-shaped PSS.

  8. Discovery of 2D Anisotropic Dirac Cones.

    Science.gov (United States)

    Feng, Baojie; Zhang, Jin; Ito, Suguru; Arita, Masashi; Cheng, Cai; Chen, Lan; Wu, Kehui; Komori, Fumio; Sugino, Osamu; Miyamoto, Koji; Okuda, Taichi; Meng, Sheng; Matsuda, Iwao

    2018-01-01

    2D anisotropic Dirac cones are observed in χ3 borophene, a monolayer boron sheet, using high-resolution angle-resolved photoemission spectroscopy. The Dirac cones are centered at the X and X' points. The data also reveal that the hybridization between borophene and Ag(111) is very weak, which explains the preservation of the Dirac cones. As χ3 borophene has been predicated to be a superconductor, the results may stimulate further research interest in the novel physics of borophene, such as the interplay between Cooper pairs and the massless Dirac fermions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. The New England Climate Adaptation Project: Enhancing Local Readiness to Adapt to Climate Change through Role-Play Simulations

    Science.gov (United States)

    Rumore, D.; Kirshen, P. H.; Susskind, L.

    2014-12-01

    Despite scientific consensus that the climate is changing, local efforts to prepare for and manage climate change risks remain limited. How we can raise concern about climate change risks and enhance local readiness to adapt to climate change's effects? In this presentation, we will share the lessons learned from the New England Climate Adaptation Project (NECAP), a participatory action research project that tested science-based role-play simulations as a tool for educating the public about climate change risks and simulating collective risk management efforts. NECAP was a 2-year effort involving the Massachusetts Institute of Technology, the Consensus Building Institute, the National Estuarine Research Reserve System, and four coastal New England municipalities. During 2012-2013, the NECAP team produced downscaled climate change projections, a summary risk assessment, and a stakeholder assessment for each partner community. Working with local partners, we used these assessments to create a tailored, science-based role-play simulation for each site. Through a series of workshops in 2013, NECAP engaged between 115-170 diverse stakeholders and members of the public in each partner municipality in playing the simulation and a follow up conversation about local climate change risks and possible adaptation strategies. Data were collected through before-and-after surveys administered to all workshop participants, follow-up interviews with 25 percent of workshop participants, public opinion polls conducted before and after our intervention, and meetings with public officials. This presentation will report our research findings and explain how science-based role-play simulations can be used to help communicate local climate change risks and enhance local readiness to adapt.

  10. Spray cone angle and air core diameter of hollow cone swirl rocket injector

    Directory of Open Access Journals (Sweden)

    Ahmad Hussein Abdul Hamid

    2011-12-01

    Full Text Available ABSTRACT : Fuel injector for liquid rocket is a very critical component since that small difference in its design can dramatically affect the combustion efficiency. The primary function of the injector is to break the fuel up into very small droplets. The smaller droplets are necessary for fast quiet ignition and to establish a flame front close to the injector head, thus shorter combustion chamber is possible to be utilized. This paper presents an experimetal investigation of a mono-propellant hollow cone swirl injector. Several injectors with different configuration were investigated under cold flow test, where water is used as simulation fluid. This investigation reveals that higher injection pressure leads to higher spray cone angle. The effect of injection pressure on spray cone angle is more prominent for injector with least number of tangential ports. Furthermore, it was found that injector with the most number of tangential ports and with the smallest tangential port diameter produces the widest resulting spray. Experimental data also tells that the diameter of an air core that forms inside the swirl chamber is largest for the injector with smallest tangential port diameter and least number of tangential ports.ABSTRAK : Injektor bahan api bagi roket cecair merupakan satu komponen yang amat kritikal memandangkan perbezaan kecil dalam reka bentuknya akan secara langsung mempengaruhi kecekapan pembakaran. Fungsi utama injektor adalah untuk memecahkan bahan api kepada titisan yang amat kecil. Titisan kecil penting untuk pembakaran pantas secara senyap dan untuk mewujudkan satu nyalaan di hadapan, berhampiran dengan kepala injektor, maka kebuk pembakaran yang lebih pendek berkemungkinan dapat digunakan. Kertas kerja ini mebentangkan satu penyelidikan eksperimental sebuah injektor ekabahan dorong geronggang kon pusar. Beberapa injektor dengan konfigurasi berbeza telah dikaji di bawah ujian aliran sejuk, di mana air digunakan sebagai bendalir

  11. Optimizing the control of foot-and-mouth disease in Denmark by simulation – the project outline

    DEFF Research Database (Denmark)

    Enøe, Claes

    2012-01-01

    The primary objective of this project was to generate scientifically based methods for improving the control and eradication of foot-and-mouth disease (FMD). This was achieved by using and optimizing existing stochastic simulation models. These include the: 1) InterSpread Plus model from Massey....... These control options included different options for emergency vaccination, zoning and culling. Optimal control/eradication strategies was evaluated based on costs, number of culled animals, epidemic duration and time to lift of restrictions on animal movements and trade. An important part of the project...... was to examine the effect of predicted structural changes in livestock populations over the coming years, including fewer but larger herds. The project consisted of 3 work packages: • WP 1: Networking, gap analysis and modelling scenarios. • WP 2: Adaptation, development and optimization of existing disease...

  12. Temporal development of extreme precipitation in Germany projected by EURO-CORDEX simulations

    Science.gov (United States)

    Brendel, Christoph; Deutschländer, Thomas

    2017-04-01

    A sustainable operation of transport infrastructure requires an enhanced resilience to the increasing impacts of climate change and related extreme meteorological events. To meet this challenge, the German Federal Ministry of Transport and Digital Infrastructure (BMVI) commenced a comprehensive national research program on safe and sustainable transport in Germany. A network of departmental research institutes addresses the "Adaptation of the German transport infrastructure towards climate change and extreme events". Various studies already have identified an increase in the average global precipitation for the 20th century. There is some indication that these increases are most visible in a rising frequency of precipitation extremes. However, the changes are highly variable between regions and seasons. With a further increase of atmospheric greenhouse gas concentrations in the 21st century, the likelihood of occurrence of such extreme events will continue to rise. A kernel estimator has been used in order to obtain a robust estimate of the temporal development of extreme precipitation events projected by an ensemble of EURO-CORDEX simulations. The kernel estimator measures the intensity of the poisson point process indicating temporal changes in the frequency of extreme events. Extreme precipitation events were selected using the peaks over threshold (POT) method with the 90th, 95th and 99th quantile of daily precipitation sums as thresholds. Application of this non-parametric approach with relative thresholds renders the use of a bias correction non-mandatory. In addition, in comparison to fitting an extreme value theory (EVT) distribution, the method is completely unsusceptible to outliers. First results show an overall increase of extreme precipitation events for Germany until the end of the 21st century. However, major differences between seasons, quantiles and the three different Representative Concentration Pathways (RCP 2.6, 4.5, and 8.5) have been

  13. Projecting Wind Energy Potential Under Climate Change with Ensemble of Climate Model Simulations

    Science.gov (United States)

    Jain, A.; Shashikanth, K.; Ghosh, S.; Mukherjee, P. P.

    2013-12-01

    Recent years have witnessed an increasing global concern over energy sustainability and security, triggered by a number of issues, such as (though not limited to): fossil fuel depletion, energy resource geopolitics, economic efficiency versus population growth debate, environmental concerns and climate change. Wind energy is a renewable and sustainable form of energy in which wind turbines convert the kinetic energy of wind into electrical energy. Global warming and differential surface heating may significantly impact the wind velocity and hence the wind energy potential. Sustainable design of wind mills requires understanding the impacts of climate change on wind energy potential, which we evaluate here with multiple General Circulation Models (GCMs). GCMs simulate the climate variables globally considering the greenhouse emission scenarios provided as Representation Concentration path ways (RCPs). Here we use new generation climate model outputs obtained from Coupled model Intercomparison Project 5(CMIP5). We first compute the wind energy potential with reanalysis data (NCEP/ NCAR), at a spatial resolution of 2.50, where the gridded data is fitted to Weibull distribution and with the Weibull parameters, the wind energy densities are computed at different grids. The same methodology is then used, to CMIP5 outputs (resultant of U-wind and V-wind) of MRI, CMCC, BCC, CanESM, and INMCM4 for historical runs. This is performed separately for four seasons globally, MAM, JJA, SON and DJF. We observe the muti-model average of wind energy density for historic period has significant bias with respect to that of reanalysis product. Here we develop a quantile based superensemble approach where GCM quantiles corresponding to selected CDF values are regressed to reanalysis data. It is observed that this regression approach takes care of both, bias in GCMs and combination of GCMs. With superensemble, we observe that the historical wind energy density resembles quite well with

  14. Correlation Between Cone Penetration Rate And Measured Cone Penetration Parameters In Silty Soils

    DEFF Research Database (Denmark)

    Poulsen, Rikke; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo

    2013-01-01

    penetration tests with varying penetration rates conducted at a test site where the subsoil primary consists of sandy silt. It is shown how a reduced penetration rate influences the cone penetration measurements e.g. the cone resistance, pore pressure, and sleeve friction.......This paper shows, how a change in cone penetration rate affects the cone penetration measurements, hence the cone resistance, pore pressure, and sleeve friction in silty soil. The standard rate of penetration is 20 mm/s, and it is generally accepted that undrained penetration occurs in clay while...... drained penetration occurs in sand. When lowering the penetration rate, the soil pore water starts to dissipate and a change in the drainage condition is seen. In intermediate soils such as silty soils, the standard cone penetration rate may result in a drainage condition that could be undrained...

  15. The Drive-Wise Project: Driving Simulator Training increases real driving performance in healthy older drivers

    OpenAIRE

    Gianclaudio eCasutt; Gianclaudio eCasutt; Gianclaudio eCasutt; Nathan eTheill; Mike eMartin; Mike eMartin; Martin eKeller; Martin eKeller; Lutz eJäncke; Lutz eJäncke; Lutz eJäncke; Lutz eJäncke

    2014-01-01

    Background: Age-related cognitive decline is often associated with unsafe driving behavior. We hypothesized that 10 active training sessions in a driving simulator increase cognitive and on-road driving performance. In addition, driving simulator training should outperform cognitive training.Methods: Ninety-one healthy active drivers (62 – 87 years) were randomly assigned to either (1) a driving simulator training group, (2) an attention training group (vigilance and selective attention), or ...

  16. The drive-wise project: driving simulator training increases real driving performance in healthy older drivers

    OpenAIRE

    Casutt, Gianclaudio; Theill, Nathan; Martin, Mike; Keller, Martin; Jäncke, Lutz

    2014-01-01

    Background: Age-related cognitive decline is often associated with unsafe driving behavior. We hypothesized that 10 active training sessions in a driving simulator increase cognitive and on-road driving performance. In addition, driving simulator training should outperform cognitive training. Methods: Ninety-one healthy active drivers (62-87 years) were randomly assigned to one of three groups: (1) a driving simulator training group, (2) an attention training group (vigilance and selective at...

  17. Metrizability of Cone Metric Spaces Via Renorming the Banach Spaces

    Directory of Open Access Journals (Sweden)

    Hossein Soleimani

    2012-09-01

    Full Text Available In this paper we show that by renorming an ordered Banach space, every cone $P$ can be converted to a normal cone with constant $K=1$ and consequently due to this approach every cone metric space is really a metric one and every theorem in metric space is valid for cone metric space automatically.

  18. Soft Cone Metric Spaces and Some Fixed Point Theorems

    OpenAIRE

    Altıntaş, İsmet; Taşköprü, Kemal

    2016-01-01

    This paper is an introduction to soft cone metric spaces. We define the concept of soft cone metric via soft element, investigate soft converges in soft cone metric spaces and prove some fixed point theorems for contractive mappings on soft cone metric spaces.

  19. Flight Dynamic Simulation with Nonlinear Aeroelastic Interaction using the ROM-ROM Procedure Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. proposes to develop an integrated flight dynamics simulation capability with nonlinear aeroelastic interactions by combining a flight dynamics...

  20. Flight Dynamic Simulation with Nonlinear Aeroelastic Interaction using the ROM-ROM Procedure Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes to develop an integrated flight dynamics simulation capability with nonlinear aeroelastic interactions by combining a flight...

  1. Improved design and data accuracy through modeling and simulation of wind tunnel facilities Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Analytical Services & Materials, Inc. (AS&M) is proposing to develop and validate the procedures and modeling necessary to simulate, using computational...

  2. Efficient Radiation Simulation in Complex Geometries with Applications to Planetary Entry Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA aerocapture missions require an accurate evaluation of radiative thermal transport in order to simulate the aerothermal environment around space vehicles....

  3. A Hardware-Accelerated Fast Adaptive Vortex-Based Flow Simulation Software Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Applied Scientific Research has recently developed a Lagrangian vortex-boundary element method for the grid-free simulation of unsteady incompressible...

  4. Integrating Portfolio Management and Simulation Concepts in the ERP Project Estimation Practice

    NARCIS (Netherlands)

    Daneva, Maia; Paech, B.; Rolland, C

    2008-01-01

    This paper presents a two-site case study on requirements-based effort estimation practices in enterprise resource planning projects. Specifically, the case study investigated the question of how to handle qualitative data and highly volatile values of project context characteristics. We counterpart

  5. Two Mechatronic Projects - an Agricultural Robot and a Flight Simulator Platform

    DEFF Research Database (Denmark)

    Sørensen, Torben; Fan, Zhun; Conrad, Finn

    2005-01-01

    product. In this paper two different, challenging mechatronic projects are presented demonstrating the engineering skills of some of the Masters of Science students at The Technical University of Denmark. The projects are: • A four wheel driven and steered autonomous agricultural robot has been designed...

  6. The LAPS Project: A tutorial, online model to simulate the atmosphere of any terrestrial planet

    Science.gov (United States)

    Turbet, M.; Schott, C.; Forget, F.

    2017-09-01

    The LAPS (Live Atmospheres-of-Planets Simulator) is a live 1-D radiative-convective version of the LMD Global Climate Model, available on http://laps.lmd.jussieu.fr. The LAPS provides an accelerated and interactive simulation of the climate of any terrestrial planet and exoplanet.

  7. A framework for using simulation methodology in ergonomics interventions in design projects

    DEFF Research Database (Denmark)

    Broberg, Ole; Duarte, Francisco; Andersen, Simone Nyholm

    2014-01-01

    The aim of this paper is to outline a framework of simulation methodology in design processes from an ergonomics perspective......The aim of this paper is to outline a framework of simulation methodology in design processes from an ergonomics perspective...

  8. MR whole spin projection: Computer-based simulation of conventional scoliosis projection; MR-Ganzwirbelsaeulenaufnahme: Computergestuetzte Simulation der konventionell-roentgenologischen Technik

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, R.; Jaeger, U.; Ostertun, B.; Kandyba, J.; Schild, H.H. [Radiologische Universitaetsklinik Bonn (Germany); Wagner, U. [Universitaetsklinik fuer Orthopaedie (Germany); Gieseke, J. [Philips Medizin Systeme (Germany)

    1999-03-01

    Purpose: Development of an MR-based imaging technique for the spine allowing reduction of frequency of conventional Nadiographs in the monitoring of juvenile scoliosis. Patients and Methods: 25 patients between the ages of 6 to 36 years were examined in supine position. Two examinations of the cervical and upper thoracic spine and of the lower thoracic and lumbar spine were performed with a 1.5 T Gyroscan ACS-NT Powertrak 6000 system with body coil employing 3D EPI-sequence (T{sub R} 17 ms, T{sub e} 9 ms, flip angle 20 , field of view 450 mm) or 3D FFE-sequences (T{sub R} 9 ms, T{sub E} 4.5 ms, flip angle 20 , field of view 450 mm) and pulse-oxymetry gating. 64 coronal slices were acquired with reconstructed slice thickness of 2 mm. Image processing was performed with an algorithm merging acquisition results into two single images in the coronal and sagittal orientations allowing measurement of the Cobb angle. Results: Mean examination time was 14 minutes per patient. Mean data processing time was seven minutes. Interobserver variance of determination of the Cobb angle was 1.8 degrees. Conclusions: It is to be hoped that MR whole spine projection will allow a reduction of the frequency of conventional projection in the monitoring of juvenile scoliosis. (orig.) [Deutsch] Ziel: Entwicklung eines MRT-basierten Verfahrens zur Darstellung der gesamten Wirbelsaeule, welches geeignet ist, die Haeufigkeit konventioneller Roentgenuntersuchungen bei der Verlaufsbeobachtung der juvenilen Skoliose zu reduzieren. Patienten und Methode: Untersucht wurden 25 Patienten im Alter zwischen 6 und 36 Jahren. Pro Patient erfolgte in Rueckenlage mittels Koerperspule jeweils eine MR-Messung der HWS und oberen BWS sowie eine der unteren BWS und LWS an einem 1,5 T Gyroscan ACS-NT-Powertrak 6000 System. Zum Einsatz kamen entweder 3D EPI-Sequenzen (T{sub R} 17 ms, T{sub E} 9 ms, Flipwinkel 20 , Gesichtsfeld 450 mm) oder 3D FFE-Sequenzen (T{sub R} 9 ms, T{sub E} 4,5 ms, Flipwinkel 20

  9. Reclip:century - a project conducting 21st century regional climate simulation runs focussing on the Greater Alpine Region

    Science.gov (United States)

    Loibl, Wolfgang

    2010-05-01

    Reclip:century (Research for Climate Protection: Century Model Runs) is a national climate simulation project aiming to deliver a range of climate simulations to provide scientifically sound data sets for the entire Greater Alpine Region, to be applied by the Austrian climate change impact research community. The simulation runs are carried out by four Austrian institutions: the Austria Institute of Technology (AIT), Vienna, heading the project, the Institute of Meteorology of the BOKU-University, Vienna, the Wegener Center for Climate and Global Change at Graz University and the Central Institute for Meteorology and Geodynamics (ZAMG), Vienna. The scenario results will demonstrate the range of climate evolution due to different greenhouse gas increase trends. The regional climate results conducted through dynamical downscaling of simulation runs from two General Circulation Model (GCM) simulation runs with two regional climate models (RCMs). A one-way double nesting approach is applied by the two RCMs COSMO CLM and MM5: the domain for the first nesting task is entire Europe and the surrounding areas with a spatial resolution of 30 to 50 km grid-spacing, depnding on the forcing data resolution. The second domain covers the Greater Alpine Region with a resolution of 0.09° or 10km grid-spacing. The GCMs, providing forcing data, are the German ECHAM5-MPI-OM (with approx. 100 km grid-spacing) and the UK HADCM3 (with approx. 200 km grid-spacing). Three IPCC - greenhouse gas scenarios (A1b, B2 and A2) for the time range 2000-2100 will be applied to compare the different greenhouse gas increase effects on regional climate. ERA40 reanalysis data for 1961-2000 GCM resolution will provide forcing for the hindcast model runs derived by the 2 RCMs. Observation data sets from HISTALP, CRU and Frei will be used to evaluate the hindcast simulations. The simulation runs are currently in progress. The contribution presents outcomes from the initial project phase, discussing

  10. Cone-Parameter Convolution Semigroups and Their Subordination

    OpenAIRE

    Pedersen, Jan; Sato, Ken-iti

    2003-01-01

    Convolution semigroups of probability measures with parameter in a cone in a Euclidean space generalize usual convolution semigroups with parameter in $[0,\\infty)$. A characterization of such semigroups is given and examples are studied. Subordination of cone-parameter convolution semigroups by cone-valued cone-parameter convolution semigroups is introduced. Its general description is given and inheritance properties are shown. In the study the distinction between cones with an...

  11. Registration-based Reconstruction of Four-dimensional Cone Beam Computed Tomography

    DEFF Research Database (Denmark)

    Christoffersen, Christian; Hansen, David Christoffer; Poulsen, Per Rugaard

    2013-01-01

    We present a new method for reconstruction of four-dimensional (4D) cone beam computed tomography from an undersampled set of X-ray projections. The novelty of the proposed method lies in utilizing optical flow based registration to facilitate that each temporal phase is reconstructed from the full...

  12. Microspectrophotometric evidence for cone monochromacy in sharks

    Science.gov (United States)

    Hart, Nathan Scott; Theiss, Susan Michelle; Harahush, Blake Kristin; Collin, Shaun Patrick

    2011-03-01

    Sharks are apex predators, and their evolutionary success is in part due to an impressive array of sensory systems, including vision. The eyes of sharks are well developed and function over a wide range of light levels. However, whilst close relatives of the sharks—the rays and chimaeras—are known to have the potential for colour vision, an evolutionary trait thought to provide distinct survival advantages, evidence for colour vision in sharks remains equivocal. Using single-receptor microspectrophotometry, we measured the absorbance spectra of visual pigments located in the retinal photoreceptors of 17 species of shark. We show that, while the spectral tuning of the rod (wavelength of maximum absorbance, λmax 484-518 nm) and cone (λmax 532-561 nm) visual pigments varies between species, each shark has only a single long-wavelength-sensitive cone type. This suggests that sharks may be cone monochromats and, therefore, potentially colour blind. Whilst cone monochromacy on land is rare, it may be a common strategy in the marine environment: many aquatic mammals (whales, dolphins and seals) also possess only a single, green-sensitive cone type. It appears that both sharks and marine mammals may have arrived at the same visual design by convergent evolution. The spectral tuning of the rod and cone pigments of sharks is also discussed in relation to their visual ecology.

  13. Design of a trichromatic cone array.

    Directory of Open Access Journals (Sweden)

    Patrick Garrigan

    2010-02-01

    Full Text Available Cones with peak sensitivity to light at long (L, medium (M and short (S wavelengths are unequal in number on the human retina: S cones are rare (<10% while increasing in fraction from center to periphery, and the L/M cone proportions are highly variable between individuals. What optical properties of the eye, and statistical properties of natural scenes, might drive this organization? We found that the spatial-chromatic structure of natural scenes was largely symmetric between the L, M and S sensitivity bands. Given this symmetry, short wavelength attenuation by ocular media gave L/M cones a modest signal-to-noise advantage, which was amplified, especially in the denser central retina, by long-wavelength accommodation of the lens. Meanwhile, total information represented by the cone mosaic remained relatively insensitive to L/M proportions. Thus, the observed cone array design along with a long-wavelength accommodated lens provides a selective advantage: it is maximally informative.

  14. The Virtual ChemLab Project: A Realistic and Sophisticated Simulation of Inorganic Qualitative Analysis

    Science.gov (United States)

    Woodfield, Brian F.; Catlin, Heidi R.; Waddoups, Gregory L.; Moore, Melissa S.; Swan, Richard; Allen, Rob; Bodily, Greg

    2004-11-01

    We have created a set of sophisticated and realistic laboratory simulations for use in freshman- and sophomore-level chemistry classes and laboratories called Virtual ChemLab. We have completed simulations for Inorganic Qualitative Analysis, Organic Synthesis and Organic Qualitative Analysis, Experiments in Quantum Chemistry, Gas Properties, Titration Experiments, and Calorimetric and Thermochemical Experiments. The purpose of our simulations is to reinforce concepts taught in the classroom, provide an environment for creative learning, and emphasize the thinking behind instructional laboratory experiments. We have used the inorganic simulation extensively with thousands of students in our department at Brigham Young University. We have learned from our evaluation that: (i) students enjoy using these simulations and find them to be an asset in learning effective problem-solving strategies, (ii) students like the fact that they can both reproduce experimental procedures and explore various topics in ways they choose, and (iii) students naturally divide themselves into two groups: creative learners, who excel in an open-ended environment of virtual laboratories, and structured learners, who struggle in this same environment. In this article, we describe the Inorganic Qualitative Analysis simulation; we also share specific evaluation findings from using the inorganic simulation in classroom and laboratory settings.

  15. Evaluation of a Pilot Project to Introduce Simulation-Based Team Training to Pediatric Surgery Trauma Room Care.

    Science.gov (United States)

    Lehner, Markus; Heimberg, Ellen; Hoffmann, Florian; Heinzel, Oliver; Kirschner, Hans-Joachim; Heinrich, Martina

    2017-01-01

    Introduction. Several studies in pediatric trauma care have demonstrated substantial deficits in both prehospital and emergency department management. Methods. In February 2015 the PAEDSIM collaborative conducted a one and a half day interdisciplinary, simulation based team-training course in a simulated pediatric emergency department. 14 physicians from the medical fields of pediatric surgery, pediatric intensive care and emergency medicine, and anesthesia participated, as well as four pediatric nurses. After a theoretical introduction and familiarization with the simulator, course attendees alternately participated in six simulation scenarios and debriefings. Each scenario incorporated elements of pediatric trauma management as well as Crew Resource Management (CRM) educational objectives. Participants completed anonymous pre- and postcourse questionnaires and rated the course itself as well as their own medical qualification and knowledge of CRM. Results. Participants found the course very realistic and selected scenarios highly relevant to their daily work. They reported a feeling of improved medical and nontechnical skills as well as no uncomfortable feeling during scenarios or debriefings. Conclusion. To our knowledge this pilot-project represents the first successful implementation of a simulation-based team-training course focused on pediatric trauma care in German-speaking countries with good acceptance.

  16. Modeling and simulation of longitudinal dynamics for Low Energy Ring–High Energy Ring at the Positron-Electron Project

    Directory of Open Access Journals (Sweden)

    C. Rivetta

    2007-02-01

    Full Text Available A time domain dynamic modeling and simulation tool for beam-cavity interactions in the Low Energy Ring (LER and High Energy Ring (HER at the Positron-Electron Project (PEP-II is presented. Dynamic simulation results for PEP-II are compared to measurements of the actual machine. The motivation for this tool is to explore the stability margins and performance limits of PEP-II radio-frequency (RF systems at future higher currents and upgraded RF configurations. It also serves as a test bed for new control algorithms and can define the ultimate limits of the low-level RF (LLRF architecture. The time domain program captures the dynamic behavior of the beam-cavity-LLRF interaction based on a reduced model. The ring current is represented by macrobunches. Multiple RF stations in the ring are represented via one or two macrocavities. Each macrocavity captures the overall behavior of all the 2 or 4 cavity RF stations. Station models include nonlinear elements in the klystron and signal processing. This enables modeling the principal longitudinal impedance control loops interacting via the longitudinal beam model. The dynamics of the simulation model are validated by comparing the measured growth rates for the LER with simulation results. The simulated behavior of the LER at increased operation currents is presented via low-mode instability growth rates. Different control strategies are compared and the effects of both the imperfections in the LLRF signal processing and the nonlinear drivers and klystrons are explored.

  17. Modeling and Simulation of Longitudinal Dynamics for Low Energy Ring_High Energy Ring at the Positron-Electron Project

    Energy Technology Data Exchange (ETDEWEB)

    Rivetta, Claudio; Mastorides, T.; Fox, J.D.; Teytelman, D.; Van Winkle, D.; /SLAC

    2007-03-06

    A time domain dynamic modeling and simulation tool for beam-cavity interactions in the Low Energy Ring (LER) and High Energy Ring (HER) at the Positron-Electron Project (PEP-II) is presented. Dynamic simulation results for PEP-II are compared to measurements of the actual machine. The motivation for this tool is to explore the stability margins and performance limits of PEP-II radio-frequency (RF) systems at future higher currents and upgraded RF configurations. It also serves as a test bed for new control algorithms and can define the ultimate limits of the low-level RF (LLRF) architecture. The time domain program captures the dynamic behavior of the beam-cavity-LLRF interaction based on a reduced model. The ring current is represented by macrobunches. Multiple RF stations in the ring are represented via one or two macrocavities. Each macrocavity captures the overall behavior of all the 2 or 4 cavity RF stations. Station models include nonlinear elements in the klystron and signal processing. This enables modeling the principal longitudinal impedance control loops interacting via the longitudinal beam model. The dynamics of the simulation model are validated by comparing the measured growth rates for the LER with simulation results. The simulated behavior of the LER at increased operation currents is presented via low-mode instability growth rates. Different control strategies are compared and the effects of both the imperfections in the LLRF signal processing and the nonlinear drivers and klystrons are explored.

  18. Evaluation of a Pilot Project to Introduce Simulation-Based Team Training to Pediatric Surgery Trauma Room Care

    Directory of Open Access Journals (Sweden)

    Markus Lehner

    2017-01-01

    Full Text Available Introduction. Several studies in pediatric trauma care have demonstrated substantial deficits in both prehospital and emergency department management. Methods. In February 2015 the PAEDSIM collaborative conducted a one and a half day interdisciplinary, simulation based team-training course in a simulated pediatric emergency department. 14 physicians from the medical fields of pediatric surgery, pediatric intensive care and emergency medicine, and anesthesia participated, as well as four pediatric nurses. After a theoretical introduction and familiarization with the simulator, course attendees alternately participated in six simulation scenarios and debriefings. Each scenario incorporated elements of pediatric trauma management as well as Crew Resource Management (CRM educational objectives. Participants completed anonymous pre- and postcourse questionnaires and rated the course itself as well as their own medical qualification and knowledge of CRM. Results. Participants found the course very realistic and selected scenarios highly relevant to their daily work. They reported a feeling of improved medical and nontechnical skills as well as no uncomfortable feeling during scenarios or debriefings. Conclusion. To our knowledge this pilot-project represents the first successful implementation of a simulation-based team-training course focused on pediatric trauma care in German-speaking countries with good acceptance.

  19. Innovative Varied-Fidelity Simulation Mobile Teaching Cart and Education Project.

    Science.gov (United States)

    Harding, Andrew D; Cullinane Whalen, Kathryn; Silverman, Bradley S

    2015-09-01

    The use of a varied-fidelity simulation mobile teaching cart is a teaching tool that offers unique advantages in the acute care setting. The cart is used to demonstrate the use of patient monitoring devices, and there are a variety of software tools available with the monitoring technology to ensure that the outputs, including electrocardiographic waves, are analyzed appropriately by nursing staff using this varied-fidelity simulation mobile teaching cart. Bringing varied-fidelity simulation to the nurses' work area is a unique application setting. Copyright © 2015 Emergency Nurses Association. Published by Elsevier Inc. All rights reserved.

  20. Modeling and Simulation for Enterprise Decision-Making: Successful Projects and Approaches

    DEFF Research Database (Denmark)

    Ramadan, Noha; Ajami, Racha; Mohamed, Nader

    Decision-making in enterprises holds different possibilities for profits and risks. Due to the complexity of decision making processes, modeling and simulation tools are being used to facilitate them and minimize the risk of making wrong decisions in the various business process phases....... In this paper, we highlight the role of modeling and simulation in enhancing decision-making processes in enterprises. In addition, we show some techniques that helped enterprises in reaching effective and efficient decisions by adopting modeling and simulation tools....

  1. Modeling and Simulation for Enterprise Decision-Making: Successful Projects and Approaches

    DEFF Research Database (Denmark)

    Ramadan, Noha; Ajami, Racha; Mohamed, Nader

    2015-01-01

    Decision-making in enterprises holds different possibilities for profits and risks. Due to the complexity of decision making processes, modeling and simulation tools are being used to facilitate them and minimize the risk of making wrong decisions in the various business process phases....... In this paper, we highlight the role of modeling and simulation in enhancing decision-making processes in enterprises. In addition, we show some techniques that helped enterprises in reaching effective and efficient decisions by adopting modeling and simulation tools....

  2. Advanced 3D Human Simulation Components with Thermal/Haptic Feedback and Tissue Deformation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In integrating the following three significant components for its research/research and development (R/R&D) effort, the power of this candidate Phase I project...

  3. Computational Tool for Coupled Simulation of Nonequilibrium Hypersonic Flows with Ablation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this SBIR project is to develop a predictive computational tool for the aerothermal environment around ablation-cooled hypersonic atmospheric entry...

  4. Computational Tool for Coupled Simulation of Nonequilibrium Hypersonic Flows with Ablation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this SBIR project is to develop a computational tool with unique predictive capabilities for the aerothermodynamic environment around ablation-cooled...

  5. Advanced 3D Human Simulation Components with Thermal/Haptic Feedback and Tissue Deformation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In integrating the following three significant components for its research/research and development (R/R&D) effort, the power of this candidate Phase II project...

  6. High Fidelity Multi-Scale Regolith Simulation Tool for ISRU Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has serious unmet needs for simulation tools capable of predicting the behavior of lunar regolith in proposed excavation, transport and handling systems....

  7. VisualCommander for Rapid End-to-End Mission Design and Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of a highly extensible and user-configurable software application for end-to-end mission simulation and design. We will leverage...

  8. Sonic Boom Vibro-Acoustic Simulations using Multiple Point Sources Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AVEC proposes an innovative concept for the evaluation of human response studies to sonic booms inside realistic structures. The approach proposed is to simulate the...

  9. Time-stepped & discrete-event simulations of electromagnetic propulsion systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a new generation of electromagnetic simulation codes with mixed resolution modeling capabilities. The need for such codes arises in many fields...

  10. Numerical Algorithms for Steady and Unsteady Multi-Disciplinary Simulation of Flight Vehicles Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new multidisciplinary software environment ('MUSE') will be developed for the simulation of flight vehicles, drawing on the results of recent research on very fast...

  11. Suit Simulator (S3) for Partial Gravity EVA Experimentation and Training Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aurora Flight Sciences, along with MIT consultants Professor Dava Newman and Professor Jeffrey Hoffman, propose to develop an EVA space suit simulator for use in...

  12. Agent-Based Simulation and Assessment of NAS Security and Safety Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The key innovation proposed here is the use of agent-based modeling and simulation to evaluate the safety of the National Airspace under crisis operations and...

  13. High Fidelity Simulation of Jet Noise Emissions from Rectangular Nozzles Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed SBIR Phase II program will lead to the validation of a state-of-the-art Large Eddy Simulation (LES) model, coupled with a Ffowcs-Williams-Hawkings...

  14. Decision Support Tool and Simulation Testbed for Airborne Spacing and Merging in Super Dense Operations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The key innovation in this effort is the development of a decision support tool and simulation testbed for Airborne Spacing and Merging (ASM). We focus on concepts...

  15. Nonlinear Aerodynamics-Structure Time Simulation for HALE Aircraft Design/Analysis Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Time simulation of a nonlinear aerodynamics model (NA) developed at Virginia Tech coupled with a nonlinear structure model (NS) is proposed as a design/analysis...

  16. Multiscale GasKinetics/Particle (MGP) Simulation for Rocket Plume/Lunar Dust Interactions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A Multiscale GasKinetic/Particle (MGP) computational method is proposed to simulate the plume-crater-interaction/dust-impingement(PCIDI) problem. The MGP method...

  17. Multiscale GasKinetics/Particle (MGP) Simulation for Rocket Plume/Lunar Dust Interactions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An efficient and accurate software package named ZMGP (ZONA Multi-scale Gaskinetic/Particle simulation package) is proposed as a 3D tool to predict the lunar dust...

  18. Robust High Fidelity Large Eddy Simulation Tool for Gas Turbine Combustors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective is to develop and demonstrate the use of Large Eddy Simulation (LES) for computations of gas turbine combustor flow and transport processes, using the...

  19. Database of Nucleon-Nucleon Scattering Cross Sections by Stochastic Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A database of nucleon-nucleon elastic differential and total cross sections will be generated by stochastic simulation of the quantum Liouville equation in the...

  20. GPU-Accelerated Sparse Matrix Solvers for Large-Scale Simulations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Many large-scale numerical simulations can be broken down into common mathematical routines. While the applications may differ, the need to perform functions such as...

  1. A Simulation Testbed for Dynamic Air Corridors within the Next Generation Air Transportation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The key innovation in this effort is the development of a simulation testbed for identifying dynamic air corridors that can increase aircraft throughput in and...

  2. Autonomic, Agent-Based Simulation Management (A2SM) Framework Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Large scale numerical simulations, as typified by climate models, space weather models, and the like, typically involve non-linear governing equations in discretized...

  3. The Drive-Wise Project: Driving Simulator Training increases real driving performance in healthy older drivers

    Directory of Open Access Journals (Sweden)

    Gianclaudio eCasutt

    2014-05-01

    Full Text Available Background: Age-related cognitive decline is often associated with unsafe driving behavior. We hypothesized that 10 active training sessions in a driving simulator increase cognitive and on-road driving performance. In addition, driving simulator training should outperform cognitive training.Methods: Ninety-one healthy active drivers (62 – 87 years were randomly assigned to either (1 a driving simulator training group, (2 an attention training group (vigilance and selective attention, or (3 a control group. The main outcome variables were on-road driving and cognitive performance. Seventy-seven participants (85% completed the training and were included in the analyses. Training gains were analyzed using a multiple regression analysis with planned comparisons.Results: The driving simulator training group showed an improvement in on-road driving performance compared to the attention training group. In addition, both training groups increased cognitive performance compared to the control group. Conclusion: Driving simulator training offers the potential to enhance driving skills in older drivers. Compared to the attention training, the simulator training seems to be a more powerful program for increasing older drivers’ safety on the road.

  4. The drive-wise project: driving simulator training increases real driving performance in healthy older drivers.

    Science.gov (United States)

    Casutt, Gianclaudio; Theill, Nathan; Martin, Mike; Keller, Martin; Jäncke, Lutz

    2014-01-01

    Age-related cognitive decline is often associated with unsafe driving behavior. We hypothesized that 10 active training sessions in a driving simulator increase cognitive and on-road driving performance. In addition, driving simulator training should outperform cognitive training. Ninety-one healthy active drivers (62-87 years) were randomly assigned to one of three groups: (1) a driving simulator training group, (2) an attention training group (vigilance and selective attention), or (3) a control group. The main outcome variables were on-road driving and cognitive performance. Seventy-seven participants (85%) completed the training and were included in the analyses. Training gains were analyzed using a multiple regression analysis with planned orthogonal comparisons. The driving simulator-training group showed an improvement in on-road driving performance compared to the attention-training group. In addition, both training groups increased cognitive performance compared to the control group. Driving simulator training offers the potential to enhance driving skills in older drivers. Compared to the attention training, the simulator training seems to be a more powerful program for increasing older drivers' safety on the road.

  5. Graphene quantum dot on boron nitride: Dirac cone replica and Hofstadter butterfly

    Science.gov (United States)

    Chizhova, L. A.; Libisch, F.; Burgdörfer, J.

    2014-10-01

    Graphene flakes placed on hexagonal boron nitride feature in the presence of a magnetic field a complex electronic structure due to a hexagonal moiré potential resulting from the van der Waals interaction with the substrate. The slight lattice mismatch gives rise to a periodic supercell potential. Zone folding is expected to create replicas of the original Dirac cone and Hofstadter butterflies. Our large-scale tight-binding simulation reveals an unexpected coexistence of a relativistic and nonrelativistic Landau level structure. The presence of the zeroth Landau level and its associated butterfly is shown to be the unambiguous signature for the occurrence of the Dirac cone replica.

  6. Clinical course, genetic etiology, and visual outcome in cone and cone-rod dystrophy

    NARCIS (Netherlands)

    Thiadens, A.A.; Phan, T.M.; Zekveld-Vroon, R.C.; Leroy, B.P.; Born, L.I. van den; Hoyng, C.B.; Klaver, C.C.; Writing Committee for the Cone Disorders Study Group, C.; Roosing, S.; Pott, J.W.; van Schooneveld, M.J.; van Moll-Ramirez, N.; van Genderen, M.M.; Boon, C.J.F.; Hollander, A.I. den; Bergen, A.A.; De Baere, E.; Cremers, F.P.; Lotery, A.J.

    2012-01-01

    OBJECTIVE: To evaluate the clinical course, genetic etiology, and visual prognosis in patients with cone dystrophy (CD) and cone-rod dystrophy (CRD). DESIGN: Clinic-based, longitudinal, multicenter study. PARTICIPANTS: Consecutive probands with CD (N = 98), CRD (N = 83), and affected relatives (N =

  7. Clinical Course, Genetic Etiology, and Visual Outcome in Cone and Cone-Rod Dystrophy

    NARCIS (Netherlands)

    Thiadens, Alberta A. H. J.; Phan, T. My Lan; Zekveld-Vroon, Renate C.; Leroy, Bart P.; van den Born, L. Ingeborgh; Hoyng, Carel B.; Klaver, Caroline C. W.; Roosing, Susanne; Pott, Jan-Willem R.; van Schooneveld, Mary J.; van Moll-Ramirez, Norka; van Genderen, Maria M.; Boon, Camiel J. F.; den Hollander, Anneke I.; Bergen, Arthur A. B.; De Baere, Elfride; Cremers, Frans P. M.; Lotery, Andrew J.

    Objective: To evaluate the clinical course, genetic etiology, and visual prognosis in patients with cone dystrophy (CD) and cone-rod dystrophy (CRD). Design: Clinic-based, longitudinal, multicenter study. Participants: Consecutive probands with CD (N = 98), CRD (N = 83), and affected relatives (N =

  8. A BPF-FBP tandem algorithm for image reconstruction in reverse helical cone-beam CT.

    Science.gov (United States)

    Cho, Seungryong; Xia, Dan; Pellizzari, Charles A; Pan, Xiaochuan

    2010-01-01

    Reverse helical cone-beam computed tomography (CBCT) is a scanning configuration for potential applications in image-guided radiation therapy in which an accurate anatomic image of the patient is needed for image-guidance procedures. The authors previously developed an algorithm for image reconstruction from nontruncated data of an object that is completely within the reverse helix. The purpose of this work is to develop an image reconstruction approach for reverse helical CBCT of a long object that extends out of the reverse helix and therefore constitutes data truncation. The proposed approach comprises of two reconstruction steps. In the first step, a chord-based backprojection-filtration (BPF) algorithm reconstructs a volumetric image of an object from the original cone-beam data. Because there exists a chordless region in the middle of the reverse helix, the image obtained in the first step contains an unreconstructed central-gap region. In the second step, the gap region is reconstructed by use of a Pack-Noo-formula-based filteredback-projection (FBP) algorithm from the modified cone-beam data obtained by subtracting from the original cone-beam data the reprojection of the image reconstructed in the first step. The authors have performed numerical studies to validate the proposed approach in image reconstruction from reverse helical cone-beam data. The results confirm that the proposed approach can reconstruct accurate images of a long object without suffering from data-truncation artifacts or cone-angle artifacts. They developed and validated a BPF-FBP tandem algorithm to reconstruct images of a long object from reverse helical cone-beam data. The chord-based BPF algorithm was utilized for converting the long-object problem into a short-object problem. The proposed approach is applicable to other scanning configurations such as reduced circular sinusoidal trajectories.

  9. A Simulation of the Front End Signal Digitization for the ATLAS Muon Spectrometer thin RPC trigger upgrade project

    Science.gov (United States)

    Meng, Xiangting; Chapman, John; Levin, Daniel; Dai, Tiesheng; Zhu, Junjie; Zhou, Bing; Um Atlas Group Team

    2016-03-01

    The ATLAS Muon Spectrometer Phase-I (and Phase-II) upgrade includes the BIS78 muon trigger detector project: two sets of eight very thin Resistive Place Chambers (tRPCs) combined with small Monitored Drift Tube (MDT) chambers in the pseudorapidity region 1Digitization of the strip signals will be done by 32-channel CERN HPTDC chips. The HPTDC is a highly configurable ASIC designed by the CERN Microelectronics group. It can work in both trigger and trigger-less modes, be readout in parallel or serially. For Phase-I operation, a stringent latency requirement of 43 bunch crossings (1075 ns) is imposed. The latency budget for the front end digitization must be kept to a minimal value, ideally less than 350 ns. We conducted detailed HPTDC latency simulations using the Behavioral Verilog code from the CERN group. We will report the results of these simulations run for the anticipated detector operating environment and for various HPTDC configurations.

  10. Assessment of simulated and projected climate change in Pakistan using IPCC AR4-based AOGCMs

    Science.gov (United States)

    Saeed, F.; Athar, H.

    2017-11-01

    A detailed spatio-temporal assessment of two basic climatic parameters (temperature and precipitation) is carried out using 22 Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4)-based atmospheric oceanic general circulation models (AOGCMs) over data-sparse and climatically vulnerable region of Pakistan (20°-37° N and 60°-78° E), for the first time, for the baseline period (1975-1999), as well as for the three projected periods during the twenty-first century centered at 2025-2049, 2050-2074, and 2075-2099, respectively, both on seasonal and on annual bases, under three Special Report on Emission Scenarios (SRES): A2, A1B, and B1. An ensemble-based approach consisting of the IPCC AR4-based AOGCMs indicates that during the winter season (from December to March), 66% of the models display robust projected increase of winter precipitation by about 10% relative to the baseline period, irrespective of emission scenario and projection period, in the upper northern subregion of Pakistan (latitude > 35° N). The projected robust changes in the temperature by the end of twenty-first century are in the range of 3 to 4 ° C during the winter season and on an annual basis, in the central and western regions of Punjab province, especially in A2 and A1B emission scenarios. In particular, the IPCC AR4 models project a progressive increase in temperature throughout Pakistan, in contrast to spatial distribution of precipitation, where spatially less uniform and robust results for projected periods are obtained on sign of change. In general, changes in both precipitation and temperature are larger in the summer season (JAS) as compared to the winter season in the coming decades, relative to the baseline period. This may require comprehensive long-term strategic policies to adapt and mitigate climate change in Pakistan, in comparison to what is currently envisaged.

  11. Tropical paleoclimates at the last glacial maximum: comparison of paleoclimate modeling intercomparison project (PMIP) simulations and paleodata

    Energy Technology Data Exchange (ETDEWEB)

    Pinot, S.; Ramstein, G.; Joussaume, S. [CEA-CNRS, Saclay, Gif-sur-Yvette (France). Lab. des Sci. du Climat et de l' Environnement; Harrison, S.P.; Prentice, I.C. [Max Planck Institute for Biogeochemistry, Postfach 10 01 64, D-07701 Jena (Germany); Guiot, J. [Laboratoire de Botanique Historique et Palynologie, Faculte de St Jerome, Marseille (France); Stute, M. [Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964 (United States)

    1999-11-04

    Seventeen simulations of the last glacial maximum (LGM) climate have been performed using atmospheric general circulation models (AGCM) in the framework of the paleoclimate modeling intercomparison project (PMIP). These simulations use the boundary conditions for CO{sub 2}, insolation and ice-sheets; surface temperatures (SSTs) are either (a) prescribed using CLIMAP data set (eight models) or (b) computed by coupling the AGCM with a slab ocean (nine models). The present-day (PD) tropical climate is correctly depicted by all the models, except the coarser resolution models, and the simulated geographical distribution of annual mean temperature is in good agreement with climatology. Tropical cooling at the LGM is less than at middle and high latitudes, but greatly exceeds the PD temperature variability. The LGM simulations with prescribed SSTs underestimate the observed temperature changes except over equatorial Africa where the models produce a temperature decrease consistent with the data. Our results confirm previous analyses showing that CLIMAP (1981) SSTs only produce a weak terrestrial cooling. When SSTs are computed, the models depict a cooling over the Pacific and Indian oceans in contrast with CLIMAP and most models produce cooler temperatures over land. Moreover four of the nine simulations, produce a cooling in good agreement with terrestrial data. Two of these model results over ocean are consistent with new SST reconstructions whereas two models simulate a homogeneous cooling. Finally, the LGM aridity inferred for most of the tropics from the data, is globally reproduced by the models with a strong underestimation for models using computed SSTs. (orig.)

  12. Use of a radial projection to reduce the statistical uncertainty of spot lateral profiles generated by Monte Carlo simulation.

    Science.gov (United States)

    Ding, Xiaoning; Liu, Wei; Shen, Jiajian; Anand, Aman; Stoker, Joshua B; Hu, Yanle; Bues, Martin

    2017-11-01

    Monte Carlo (MC) simulation has been used to generate commissioning data for the beam modeling of treatment planning system (TPS). We have developed a method called radial projection (RP) for postprocessing of MC-simulation-generated data. We used the RP method to reduce the statistical uncertainty of the lateral profile of proton pencil beams with axial symmetry. The RP method takes advantage of the axial symmetry of dose distribution to use the mean value of multiple independent scores as the representative score. Using the mean as the representative value rather than any individual score results in substantial reduction in statistical uncertainty. Herein, we present the concept and step-by-step implementation of the RP method, as well as show the advantage of the RP method over conventional measurement methods for generating lateral profile. Lateral profiles generated by both methods were compared to demonstrate the uncertainty reduction qualitatively, and standard error comparison was performed to demonstrate the reduction quantitatively. The comparisons showed that statistical uncertainty was reduced substantially by the RP method. Using the RP method to postprocess MC data, the corresponding MC simulation time was reduced by a factor of 10 without quality reduction in the generated result from the MC data. We concluded that the RP method is an effective technique to increase MC simulation efficiency for generating lateral profiles for axially symmetric pencil beams. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  13. Turning cones off: the role of the 9-methyl group of retinal in red cones.

    Science.gov (United States)

    Estevez, Maureen E; Ala-Laurila, Petri; Crouch, Rosalie K; Cornwall, M Carter

    2006-12-01

    Our ability to see in bright light depends critically on the rapid rate at which cone photoreceptors detect and adapt to changes in illumination. This is achieved, in part, by their rapid response termination. In this study, we investigate the hypothesis that this rapid termination of the response in red cones is dependent on interactions between the 9-methyl group of retinal and red cone opsin, which are required for timely metarhodopsin (Meta) II decay. We used single-cell electrical recordings of flash responses to assess the kinetics of response termination and to calculate guanylyl cyclase (GC) rates in salamander red cones containing native visual pigment as well as visual pigment regenerated with 11-cis 9-demethyl retinal, an analogue of retinal in which the 9-methyl group is missing. After exposure to bright light that photoactivated more than approximately 0.2% of the pigment, red cones containing the analogue pigment had a slower recovery of both flash response amplitudes and GC rates (up to 10 times slower at high bleaches) than red cones containing 11-cis retinal. This finding is consistent with previously published biochemical data demonstrating that red cone opsin regenerated in vitro with 11-cis 9-demethyl retinal exhibited prolonged activation as a result of slowed Meta II decay. Our results suggest that two different mechanisms regulate the recovery of responsiveness in red cones after exposure to light. We propose a model in which the response recovery in red cones can be regulated (particularly at high light intensities) by the Meta II decay rate if that rate has been inhibited. In red cones, the interaction of the 9-methyl group of retinal with opsin promotes efficient Meta II decay and, thus, the rapid rate of recovery.

  14. Collisionless loss-cone refilling: there is no final parsec problem

    Science.gov (United States)

    Gualandris, Alessia; Read, Justin I.; Dehnen, Walter; Bortolas, Elisa

    2017-01-01

    Coalescing massive black hole binaries, formed during galaxy mergers, are expected to be a primary source of low-frequency gravitational waves. Yet in isolated gas-free spherical stellar systems, the hardening of the binary stalls at parsec-scale separations owing to the inefficiency of relaxation-driven loss-cone refilling. Repopulation via collisionless orbit diffusion in triaxial systems is more efficient, but published simulation results are contradictory. While sustained hardening has been reported in simulations of galaxy mergers with N ˜ 106 stars and in early simulations of rotating models, in isolated non-rotating triaxial models the hardening rate continues to fall with increasing N, a signature of spurious two-body relaxation. We present a novel approach for studying loss-cone repopulation in galactic nuclei. Since loss-cone repopulation in triaxial systems owes to orbit diffusion, it is a purely collisionless phenomenon and can be studied with an approximated force calculation technique, provided the force errors are well behaved and sufficiently small. We achieve this using an accurate fast multipole method and define a proxy for the hardening rate that depends only on stellar angular momenta. We find that the loss cone is efficiently replenished even in very mildly triaxial models (with axis ratios 1:0.9:0.8). Such triaxiality is unavoidable following galactic mergers and can drive binaries into the gravitational wave regime. We conclude that there is no `final parsec problem'.

  15. The 1993 timber assessment market model: structure, projections, and policy simulations.

    Science.gov (United States)

    Darius M. Adams; Richard W. Haynes

    1996-01-01

    The 1993 timber assessment market model (TAMM) is a spatial model of the solidwood and timber inventory elements of the U.S. forest products sector. The TAMM model provides annual projections of volumes and prices in the solidwood products and sawtimber stumpage markets and estimates of total timber harvest and inventory by geographic region for periods of up to 50...

  16. Investigation of load reduction for a variable speed, variable pitch, and variable coning wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, K. [Univ. of Utah, Salt Lake City, UT (United States)

    1997-12-31

    A two bladed, variable speed and variable pitch wind turbine was modeled using ADAMS{reg_sign} to evaluate load reduction abilities of a variable coning configuration as compared to a teetered rotor, and also to evaluate control methods. The basic dynamic behavior of the variable coning turbine was investigated and compared to the teetered rotor under constant wind conditions as well as turbulent wind conditions. Results indicate the variable coning rotor has larger flap oscillation amplitudes and much lower root flap bending moments than the teetered rotor. Three methods of control were evaluated for turbulent wind simulations. These were a standard IPD control method, a generalized predictive control method, and a bias estimate control method. Each control method was evaluated for both the variable coning configuration and the teetered configuration. The ability of the different control methods to maintain the rotor speed near the desired set point is evaluated from the RMS error of rotor speed. The activity of the control system is evaluated from cycles per second of the blade pitch angle. All three of the methods were found to produce similar results for the variable coning rotor and the teetered rotor, as well as similar results to each other.

  17. Multimodel simulations of carbon monoxide: Comparison with observations and projected near-future changes

    NARCIS (Netherlands)

    Shindell, D.T.; Faluvegi, G.; Stevenson, D.S.; Krol, M.C.; Emmons, L.K.; Lamarque, J.F.; Petron, G.; Dentener, F.J.; Ellingsen, K.; Schultz, M.G.; Wild, O.; Amann, M.; Atherton, C.S.; Bergmann, D.J.; Bey, I.; Butler, T.; Cofala, J.; Collins, W.J.; Derwent, R.G.; Doherty, R.M.; Drevet, J.; Eskes, H.J.; Fiore, A.M.; Gauss, M.; Hauglustaine, D.A.; Horowitz, L.W.; Isaksen, I.S.A.; Lawrence, M.G.; Montanaro, V.; Muller, J.F.; Pitari, G.; Prather, M.J.; Pyle, J.A.; Rast, S.; Rodriguez, J.M.; Sanderson, M.G.; Savage, N.H.; Strahan, S.E.; Sudo, K.; Szopa, S.; Unger, N.; Noije, van T.P.C.; Zeng, G.

    2006-01-01

    We analyze present-day and future carbon monoxide (CO) simulations in 26 state-of-the-art atmospheric chemistry models run to study future air quality and climate change. In comparison with near-global satellite observations from the MOPITT instrument and local surface measurements, the models show

  18. Dosimetric characteristics of the small diameter BrainLab™ cones used for stereotactic radiosurgery.

    Science.gov (United States)

    Khelashvili, Gocha; Chu, James; Diaz, Aidnag; Turian, Julius

    2012-01-05

    The purpose was to study the dosimetric characteristics of the small diameter (≤ 10.0 mm) BrainLAB cones used for stereotactic radiosurgery (SRS) treatments in conjunction with a Varian Trilogy accelerator. Required accuracy and precision in dose delivery during SRS can be achieved only when the geometric and dosimetric characteristics of the small radiation fields is completely understood. Although a number of investigators have published the dosimetric characteristics of SRS cones, to our knowledge, there is no generally accepted value for the relative output factor (ROF) for the 5.0 mm diameter cone. Therefore, we have investigated the dosimetric properties of the small (≤ 10.0 mm) diameter BrainLAB SRS cones used in conjunction with the iPlan TPS and a Trilogy linear accelerator with a SRS beam mode. Percentage depth dose (PDD), off-axis ratios (OAR), and ROF were measured using a SRS diode and verified with Monte Carlo (MC) simulations. The dependence of ROF on detector material response was studied. The dependence of PDD, OAR, and ROF on the alignment of the beam CAX with the detector motion line was also investigated using MC simulations. An agreement of 1% and 1 mm was observed between measurements and MC for PDD and OAR. The calculated ROF for the 5.0 mm diameter cone was 0.692 ± 0.008--in good agreement with the measured value of 0.683 ± 0.007 after the diode response was corrected. Simulations of the misalignment between the beam axis and detector motion axis for angles between 0.5°-1.0° have shown a deviation > 2% in PDD beyond a certain depth. We have also provided a full set of dosimetric data for BrainLAB SRS cones. Monte Carlo calculated ROF values for cones with diameters less than 10.0 mm agrees with measured values to within 1.8%. Care should be exercised when measuring PDD and OAR for small cones. We recommend the use of MC to confirm the measurement under these conditions.

  19. Simulation

    DEFF Research Database (Denmark)

    Gould, Derek A; Chalmers, Nicholas; Johnson, Sheena J

    2012-01-01

    Recognition of the many limitations of traditional apprenticeship training is driving new approaches to learning medical procedural skills. Among simulation technologies and methods available today, computer-based systems are topical and bring the benefits of automated, repeatable, and reliable...... performance assessments. Human factors research is central to simulator model development that is relevant to real-world imaging-guided interventional tasks and to the credentialing programs in which it would be used....

  20. Few-view and limited-angle cone-beam megavoltage CT for breast localization in radiation therapy

    Science.gov (United States)

    Yu, Lifeng; Pan, Xiaochuan; Pelizzari, Charles A.; Martel, Mary

    2004-05-01

    In radiation therapy for breast cancer treatment, information about the external (skin) and internal (lung) boundaries is highly useful for determining the relative locations of the target and lung. In this work, we investigate the feasibility of tomographic reconstruction from few-view and limited-angle cone-beam projections acquired in radiation therapy unit for obtaining critical boundary information. From the few-view and limited-angle projections acquired directly in the treatment machine with an amorphous silicon electronic portal imaging device (EPID), We compared and evaluated the performance of the conventional cone-beam FDK algorithm and an iterative algorithm based upon the maximum-likelihood method for transmission tomography (ML-TR). Preliminary results demonstrated that the ML-TR algorithm is more promising than is the cone-beam FDK algorithm. Useful boundary information for breast localization can be obtained with very few projections in a limited angle range from the reconstruction of ML-TR algorithm.

  1. The NINJA-2 project: Detecting and characterizing gravitational waveforms modelled using numerical binary black hole simulations

    CERN Document Server

    :,; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Accadia, T; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ain, A; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Andersen, M; Anderson, R; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Austin, L; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauchrowitz, J; Bauer, Th S; Behnke, B; Bejger, M; Beker, M G; Belczynski, C; Bell, A S; Bell, C; Bergmann, G; Bersanetti, D; Bertolini, A; Betzwieser, J; Beyersdorf, P T; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bloemen, S; Blom, M; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bosi, L; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Buchman, S; Bulik, T; Bulten, H J; Buonanno, A; Burman, R; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Bustillo, J Calderón; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castiglia, A; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Celerier, C; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Chow, J; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corpuz, A; Corsi, A; Costa, C A; Coughlin, M W; Coughlin, S; Coulon, J -P; Countryman, S; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Dahl, K; Canton, T Dal; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; Debreczeni, G; Degallaix, J; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Donath, A; Donovan, F; Dooley, K L; Doravari, S; Dossa, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Effler, A; Eggenstein, H; Ehrens, P; Eichholz, J; Eikenberry, S S; Endrőczi, G; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fehrmann, H; Fejer, M M; Feldbaum, D; Feroz, F; Ferrante, I; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Fournier, J -D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gair, J; Gammaitoni, L; Gaonkar, S; Garufi, F; Gehrels, N; Gemme, G; Genin, E; Gennai, A; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, C; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Gräf, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C; Gushwa, K; Gustafson, E K; Gustafson, R; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hart, M; Hartman, M T; Haster, C -J; Haughian, K; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Hooper, S; Hopkins, P; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Ingram, D R; Inta, R; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; James, E; Jang, H; Jaranowski, P; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karlen, J; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, C; Kim, K; Kim, N; Kim, N G; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D B; Kremin, A; Kringel, V; Krishnan, B; Królak, A; Kuehn, G; Kumar, A; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Kwee, P; Landry, M; Lantz, B; Larson, S; Lasky, P D; Lawrie, C; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C -H; Lee, H K; Lee, H M; Lee, J; Leonardi, M; Leong, J R; Roux, A Le; Leroy, N; Letendre, N; Levin, Y; Levine, B; Lewis, J; Li, T G F; Libbrecht, K; Libson, A; Lin, A C; Littenberg, T B; Litvine, V; Lockerbie, N A; Lockett, V; Lodhia, D; Loew, K; Logue, J; Lombardi, A L; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J; Lubinski, M J; Lück, H; Luijten, E; Lundgren, A P; Lynch, R; Ma, Y; Macarthur, J; Macdonald, E P; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; Magana-Sandoval, F; Mageswaran, M; Maglione, C; Mailand, K; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Manca, G M; Mandel, I; Mandic, V; Mangano, V; Mangini, N; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A; Maros, E; Marque, J; Martelli, F; Martin, I W; Martin, R M; Martinelli, L; Martynov, D; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Matichard, F; Matone, L; Matzner, R A; Mavalvala, N; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McGuire, S C; McIntyre, G; McIver, J; McLin, K; Meacher, D; Meadors, G D; Mehmet, M; Meidam, J; Meinders, M; Melatos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C; Meyers, P; Miao, H; Michel, C; Mikhailov, E E; Milano, L; Milde, S; Miller, J; Minenkov, Y; Mingarelli, C M F; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moe, B; Moesta, P; Mohan, M; Mohapatra, S R P; Moraru, D; Moreno, G; Morgado, N; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Mukherjee, S; Mullavey, A; Munch, J; Murphy, D; Murray, P G; Mytidis, A; Nagy, M F; Kumar, D Nanda; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nelemans, G; Neri, I; Neri, M; Newton, G; Nguyen, T; Nitz, A; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Ochsner, E; O'Dell, J; Oelker, E; Oh, J J; Oh, S H; Ohme, F; Oppermann, P; O'Reilly, B; O'Shaughnessy, R; Osthelder, C; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Padilla, C; Pai, A; Palashov, O; Palomba, C; Pan, H; Pan, Y; Pankow, C; Paoletti, F; Paoletti, R; Papa, M A; Paris, H; Pasqualetti, A; Passaquieti, R; Passuello, D; Pedraza, M; Penn, S; Perreca, A; Phelps, M; Pichot, M; Pickenpack, M; Piergiovanni, F; Pierro, V; Pinard, L; Pinto, I M; Pitkin, M; Poeld, J; Poggiani, R; Poteomkin, A; Powell, J; Prasad, J; Premachandra, S; Prestegard, T; Price, L R; Prijatelj, M; Privitera, S; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Qin, J; Quetschke, V; Quintero, E; Quiroga, G; Quitzow-James, R; Raab, F J; Rabeling, D S; Rácz, I; Radkins, H; Raffai, P; Raja, S; Rajalakshmi, G; Rakhmanov, M; Ramet, C; Ramirez, K; Rapagnani, P; Raymond, V; Re, V; Read, J; Reed, C M; Regimbau, T; Reid, S; Reitze, D H; Rhoades, E; Ricci, F; Riles, K; Robertson, N A; Robinet, F; Rocchi, A; Rodruck, M; Rolland, L; Rollins, J G; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Salemi, F; Sammut, L; Sandberg, V; Sanders, J R; Sannibale, V; Santiago-Prieto, I; Saracco, E; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Savage, R; Scheuer, J; Schilling, R; Schnabel, R; Schofield, R M S; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Shaddock, D; Shah, S; Shahriar, M S; Shaltev, M; Shapiro, B; Shawhan, P; Shoemaker, D H; Sidery, T L; Siellez, K; Siemens, X; Sigg, D; Simakov, D; Singer, A; Singer, L; Singh, R; Sintes, A M; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M; Smith, R J E; Smith-Lefebvre, N D; Son, E J; Sorazu, B; Souradeep, T; Sperandio, L; Staley, A; Stebbins, J; Steinlechner, J; Steinlechner, S; Stephens, B C; Steplewski, S; Stevenson, S; Stone, R; Stops, D; Strain, K A; Straniero, N; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Susmithan, S; Sutton, P J; Swinkels, B; Tacca, M; Talukder, D; Tanner, D B; Tarabrin, S P; Taylor, R; ter Braack, A P M; Thirugnanasambandam, M P; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, V; Tokmakov, K V; Tomlinson, C; Toncelli, A; Tonelli, M; Torre, O; Torres, C V; Torrie, C I; Travasso, F; Traylor, G; Tse, M; Ugolini, D; Unnikrishnan, C S; Urban, A L; Urbanek, K; Vahlbruch, H; Vajente, G; Valdes, G; Vallisneri, M; Brand, J F J van den; Broeck, C Van Den; van der Putten, S; van der Sluys, M V; van Heijningen, J; van Veggel, A A; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Verma, S S; Vetrano, F; Viceré, A; Vincent-Finley, R; Vinet, J -Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Vousden, W D; Vyachanin, S P; Wade, A; Wade, L; Wade, M; Walker, M; Wallace, L; Wang, M; Wang, X; Ward, R L; Was, M; Weaver, B; Wei, L -W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; West, M; Westphal, T; Wette, K; Whelan, J T; Whitcomb, S E; White, D J; Whiting, B F; Wiesner, K; Wilkinson, C; Williams, K; Williams, L; Williams, R; Williams, T; Williamson, A R; Willis, J L; Willke, B; Wimmer, M; Winkler, W; Wipf, C C; Wiseman, A G; Wittel, H; Woan, G; Worden, J; Yablon, J; Yakushin, I; Yamamoto, H; Yancey, C C; Yang, H; Yang, Z; Yoshida, S; Yvert, M; Zadrożny, A; Zanolin, M; Zendri, J -P; Zhang, Fan; Zhang, L; Zhao, C; Zhu, X J; Zucker, M E; Zuraw, S; Zweizig, J; Boyle, M; Brügmann, B; Buchman, L T; Campanelli, M; Chu, T; Etienne, Z B; Hannam, M; Healy, J; Hinder, I; Kidder, L E; Laguna, P; Liu, Y T; London, L; Lousto, C O; Lovelace, G; MacDonald, I; Marronetti, P; Mösta, P; Müller, D; Mundim, B C; Nakano, H; Paschalidis, V; Pekowsky, L; Pollney, D; Pfeiffer, H P; Ponce, M; Pürrer, M; Reifenberger, G; Reisswig, C; Santamaría, L; Scheel, M A; Shapiro, S L; Shoemaker, D; Sopuerta, C F; Sperhake, U; Szilágyi, B; Taylor, N W; Tichy, W; Tsatsin, P; Zlochower, Y

    2014-01-01

    The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave astrophysics communities. The purpose of NINJA is to study the ability to detect gravitational waves emitted from merging binary black holes and recover their parameters with next-generation gravitational-wave observatories. We report here on the results of the second NINJA project, NINJA-2, which employs 60 complete binary black hole hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. In a "blind injection challenge" similar to that conducted in recent LIGO and Virgo science runs, we added 7 hybrid waveforms to two months of data recolored to predictions of Advanced LIGO and Advanced Virgo sensitivity curves during their first observing runs. The resulting data was analyzed by gravitational-wave detection algorithms and 6 of the waveforms were recovered w...

  2. An Assessment of Artificial Compressibility and Pressure Projection Methods for Incompressible Flow Simulations

    Science.gov (United States)

    Kwak, Dochan; Kiris, C.; Smith, Charles A. (Technical Monitor)

    1998-01-01

    Performance of the two commonly used numerical procedures, one based on artificial compressibility method and the other pressure projection method, are compared. These formulations are selected primarily because they are designed for three-dimensional applications. The computational procedures are compared by obtaining steady state solutions of a wake vortex and unsteady solutions of a curved duct flow. For steady computations, artificial compressibility was very efficient in terms of computing time and robustness. For an unsteady flow which requires small physical time step, pressure projection method was found to be computationally more efficient than an artificial compressibility method. This comparison is intended to give some basis for selecting a method or a flow solution code for large three-dimensional applications where computing resources become a critical issue.

  3. Interrelationships Between 3 Keratoconic Cone Parameters.

    Science.gov (United States)

    Tu, Kyaw L; Tourkmani, Abdo K; Srinivas, Singaram

    2017-09-01

    To find out the interrelationships between 3 parameters of the keratoconic cone. A total of 101 keratoconic eyes of 58 patients were included in this retrospective case series study. A complete eye examination was performed. Kmax (K) and pachymetry at the thinnest point (T) were obtained from the Pentacam tomographer. The vertex to thinnest pachymetry distance (D for decentration) was calculated using trigonometry. Pearson correlation coefficients between T and D, between T and K, and between D and K were calculated. There is a statistically significant positive correlation between thinnest point pachymetry and decentration (R = 0.366, P = 0.0002) and also statistically significant negative correlation between thinnest point pachymetry and Kmax (R = -0.719, P < 0.00001) and decentration and Kmax (R = -0.281, P = 0.0044). The interrelationships between the 3 keratoconic cone parameters suggest that the thinner cones are largely central, that is, decenter less, but show greater steepening.

  4. Hygroscopic motions of fossil conifer cones.

    Science.gov (United States)

    Poppinga, Simon; Nestle, Nikolaus; Šandor, Andrea; Reible, Bruno; Masselter, Tom; Bruchmann, Bernd; Speck, Thomas

    2017-01-11

    Conifer cones represent natural, woody compliant structures which move their scales as passive responses to changes in environmental humidity. Here we report on water-driven opening and closing motions in coalified conifer cones from the Eemian Interglacial (approx. 126,000-113,000 years BP) and from the Middle Miocene (approx. 16.5 to 11.5 million years BP). These cones represent by far the oldest documented evidence of plant parts showing full functionality of such passive hydraulically actuated motion. The functional resilience of these structures is far beyond the biological purpose of seed dispersal and protection and is because of a low level of mineralization of the fossils. Our analysis emphasizes the functional-morphological integrity of these biological compliant mechanisms which, in addition to their biological fascination, are potentially also role models for resilient and maintenance-free biomimetic applications (e.g., adaptive and autonomously moving structures including passive hydraulic actuators).

  5. Experience with simulators for development and evaluation of operator support systems at the OECD Halden reactor project

    Energy Technology Data Exchange (ETDEWEB)

    Berg, O.; Holmstroem, C.O.B.; Volden, F. [Inst. for Energiteknikk, Halden (Norway)

    1994-12-31

    The OECD Halden Reactor Project carries out research and development of computer-based systems for nuclear power plants. The aim is to design, build and evaluate computer-based systems which can assist and support operators in their various cognitive tasks and through this improve the total performance and safety of complex plant operations. The operator support systems are tested and evaluated through experiments in the Halden Man-Machine Laboratory using the NORS pressurized water reactor simulator. An experiment to assess the impact on operator behaviour when using a rule-based expert system for fault diagnosis will be described. Two different computerised operator support systems utilising on-line simulation models are described. The first system is the core surveillance system SCORPIO which has been in operation at the Ringhals plant in Sweden since the end of 1987. This system performs core monitoring functions by logging and presenting measured data together with results from three-dimensional simulations of the core. In predictive mode the development during the coming two days may be simulated, and a strategy generator is available to facilitate transient planning. The second system is an early fault detection system for the feedwater system installed in the Loviisa plant in Finland. The method used is to run small, decoupled mathematical models which calculate the state of the process assuming no faults. The behaviour of these models is then compared with the behaviour of the real process, and if there is a deviation, an alarm is triggered. For both systems special emphasize has been put on making a user-friendly operator interface where simulator data are combined with measurements. (orig.) (8 refs., 10 figs.).

  6. Design and simulation of the rotating test rig in the INDUFLAP project

    DEFF Research Database (Denmark)

    Barlas, Thanasis K.; Aagaard Madsen, Helge; Løgstrup Andersen, Tom

    The general description and objectives of the rotating test rig at the Risø campus of DTU are presented, as used for the aeroelastic testing of a controllable rubber trailing edge flap (CRTEF) system in the INDUFLAP project. The design of all new components is presented, including the electrical...... of the setup are documented. Finally, the measured structural dynamics of the rig setup are presented....

  7. The Dust Management Project: Characterizing Lunar Environments and Dust, Developing Regolith Mitigation Technology and Simulants

    Science.gov (United States)

    Hyatt, Mark J.; Straka, Sharon A.

    2010-01-01

    A return to the Moon to extend human presence, pursue scientific activities, use the Moon to prepare for future human missions to Mars, and expand Earth?s economic sphere, will require investment in developing new technologies and capabilities to achieve affordable and sustainable human exploration. From the operational experience gained and lessons learned during the Apollo missions, conducting long-term operations in the lunar environment will be a particular challenge, given the difficulties presented by the unique physical properties and other characteristics of lunar regolith, including dust. The Apollo missions and other lunar explorations have identified significant lunar dust-related problems that will challenge future mission success. Comprised of regolith particles ranging in size from tens of nanometers to microns, lunar dust is a manifestation of the complex interaction of the lunar soil with multiple mechanical, electrical, and gravitational effects. The environmental and anthropogenic factors effecting the perturbation, transport, and deposition of lunar dust must be studied in order to mitigate it?s potentially harmful effects on exploration systems and human explorers. The Dust Management Project (DMP) is tasked with the evaluation of lunar dust effects, assessment of the resulting risks, and development of mitigation and management strategies and technologies related to Exploration Systems architectures. To this end, the DMP supports the overall goal of the Exploration Technology Development Program (ETDP) of addressing the relevant high priority technology needs of multiple elements within the Constellation Program (CxP) and sister ETDP projects. Project scope, plans, and accomplishments will be presented.

  8. Density-matrix simulation of small surface codes under current and projected experimental noise

    Science.gov (United States)

    O'Brien, T. E.; Tarasinski, B.; DiCarlo, L.

    2017-09-01

    We present a density-matrix simulation of the quantum memory and computing performance of the distance-3 logical qubit Surface-17, following a recently proposed quantum circuit and using experimental error parameters for transmon qubits in a planar circuit QED architecture. We use this simulation to optimize components of the QEC scheme (e.g., trading off stabilizer measurement infidelity for reduced cycle time) and to investigate the benefits of feedback harnessing the fundamental asymmetry of relaxation-dominated error in the constituent transmons. A lower-order approximate calculation extends these predictions to the distance-5 Surface-49. These results clearly indicate error rates below the fault-tolerance threshold of the surface code, and the potential for Surface-17 to perform beyond the break-even point of quantum memory. However, Surface-49 is required to surpass the break-even point of computation at state-of-the-art qubit relaxation times and readout speeds.

  9. FANS Simulation of Propeller Wash at Navy Harbors (ESTEP Project ER-201031)

    Science.gov (United States)

    2016-08-01

    with two ducted propellers. This model enables us to evaluate the effect of water depth , ship speed, propeller rotating speed, and pier wall...boat, 7 fenders and 12 mooring lines. In these simulations, a very shallow water depth of 28 ft was intentionally chosen to confine the underkeel...2011), hurricane wave loads on offshore platform and jack-up structure (Chen, 2010, 2013), vortex-induced vibration of deep water risers (Huang, Chen

  10. GPS Radiation Measurements: Instrument Modeling and Simulation (Project w14_gpsradiation)

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, John P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-29

    The following topics are covered: electron response simulations and typical calculated response. Monte Carlo calculations of the response of future charged particle instruments (dosimeters) intended to measure the flux of charged particles in space were performed. The electron channels are called E1- E11 – each of which is intended to detect a different range of electron energies. These instruments are on current and future GPS satellites.

  11. The Living Heart Project: A robust and integrative simulator for human heart function

    Science.gov (United States)

    Baillargeon, Brian; Rebelo, Nuno; Fox, David D.; Taylor, Robert L.; Kuhl, Ellen

    2014-01-01

    The heart is not only our most vital, but also our most complex organ: Precisely controlled by the interplay of electrical and mechanical fields, it consists of four chambers and four valves, which act in concert to regulate its filling, ejection, and overall pump function. While numerous computational models exist to study either the electrical or the mechanical response of its individual chambers, the integrative electro-mechanical response of the whole heart remains poorly understood. Here we present a proof-of-concept simulator for a four-chamber human heart model created from computer topography and magnetic resonance images. We illustrate the governing equations of excitation-contraction coupling and discretize them using a single, unified finite element environment. To illustrate the basic features of our model, we visualize the electrical potential and the mechanical deformation across the human heart throughout its cardiac cycle. To compare our simulation against common metrics of cardiac function, we extract the pressure-volume relationship and show that it agrees well with clinical observations. Our prototype model allows us to explore and understand the key features, physics, and technologies to create an integrative, predictive model of the living human heart. Ultimately, our simulator will open opportunities to probe landscapes of clinical parameters, and guide device design and treatment planning in cardiac diseases such as stenosis, regurgitation, or prolapse of the aortic, pulmonary, tricuspid, or mitral valve. PMID:25267880

  12. Tantalum Cones in Revision Total Knee Arthroplasty.

    Science.gov (United States)

    Kim, Eric G; Patel, Nirav K; Chughtai, Morad; Elmallah, Randa D K; Delanois, Ronald E; Harwin, Steven F; Mont, Michael A

    2016-11-01

    The best strategy to address large bony defects in revision total knee arthroplasty has yet to be determined. The relatively recent development of porous tantalum cones and their use to address massive bone loss in knee arthroplasty has shown promising short- and intermediate-term results. The purpose of this review is to present the current literature on: (1) basic science of porous tantalum, (2) classification and treatment for bone loss, (3) clinical results, and (4) evolution of newer generation cones. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  13. The Change of First-flowering Date over South Korea Projected from Downscaled IPCC AR5 Simulation: Peach and Pear

    Science.gov (United States)

    Ahn, J. B.; Hur, J.

    2014-12-01

    The variations in the first-flowering date (FFD) of peach (Prunus persica) and pear (Pyrus pyrifolia) under future climate change in South Korea are investigated using simulations obtained from five models of the fifth Coupled Model Intercomparison Project. For the study, daily temperature simulations with Historical (1986-2005), and RCP (2071-2090) 4.5 and 8.5 scenarios are statistically downscaled to 50 peach and pear FFD (FFDpeach and FFDpear, respectively) observation sites over South Korea. The number of days transformed to standard temperature (DTS) method is selected as the phenological model and applied to simulations for estimating FFDpeach and FFDpear over South Korea, due to its superior performance on the target plants and region compared to the growing degree days (GDD) and chill days (CD) methods. In the analysis, mean temperatures for early spring (February to April) over South Korea in 2090 under RCP4.5 and 8.5 scenarios are expected to have increased by 1.9K and 3.3K, respectively. Among the early spring months of February to April, February shows the largest temperature increase of 2.1K and 3.7K for RCP4.5 and 8.5 scenarios, respectively. The increased temperature during February and March accelerates the plant growth rate and thereby advances FFDpeach by 7.0 and 12.7 days and FFDpear by 6.1 and 10.7 days, respectively. These results imply that the present flowering of peach and pear in the middle of April will have advanced to late March or early April by the end of this century. Acknowledgements This work was carried out with the support of the Rural Development Administration Cooperative Research Program for Agriculture Science and Technology Development under Grant Project No. PJ009953, Republic of Korea.

  14. Force Projection Site Evaluation Using the Electric Cone Penetrometer (ECP) and the Dynamic Cone Penetrometer (DCP)

    Science.gov (United States)

    1994-04-01

    611V7 FRITKN RAllO (%) CBR Figure 24. ECP versus CBR correlation tor group 1 soils GROUP 2: ML, CL, OL, MH CBR = 2.7183A(O.1 180"FR + 0.00214"TP) 1 10 100...1000 1500 20AJO 2500 3000 3500 4000 4c0 .5000 5500 6000 6500 7000) Figure El. ECP TP versus depth for W2101 W21 1 Friction Rallo M% 0 1 2 3 4 5 6 7 8

  15. 3D Alternating Direction TV-Based Cone-Beam CT Reconstruction with Efficient GPU Implementation

    Directory of Open Access Journals (Sweden)

    Ailong Cai

    2014-01-01

    Full Text Available Iterative image reconstruction (IIR with sparsity-exploiting methods, such as total variation (TV minimization, claims potentially large reductions in sampling requirements. However, the computation complexity becomes a heavy burden, especially in 3D reconstruction situations. In order to improve the performance for iterative reconstruction, an efficient IIR algorithm for cone-beam computed tomography (CBCT with GPU implementation has been proposed in this paper. In the first place, an algorithm based on alternating direction total variation using local linearization and proximity technique is proposed for CBCT reconstruction. The applied proximal technique avoids the horrible pseudoinverse computation of big matrix which makes the proposed algorithm applicable and efficient for CBCT imaging. The iteration for this algorithm is simple but convergent. The simulation and real CT data reconstruction results indicate that the proposed algorithm is both fast and accurate. The GPU implementation shows an excellent acceleration ratio of more than 100 compared with CPU computation without losing numerical accuracy. The runtime for the new 3D algorithm is about 6.8 seconds per loop with the image size of 256×256×256 and 36 projections of the size of 512×512.

  16. High quality 4D cone-beam CT reconstruction using motion-compensated total variation regularization

    Science.gov (United States)

    Zhang, Hua; Ma, Jianhua; Bian, Zhaoying; Zeng, Dong; Feng, Qianjin; Chen, Wufan

    2017-04-01

    Four dimensional cone-beam computed tomography (4D-CBCT) has great potential clinical value because of its ability to describe tumor and organ motion. But the challenge in 4D-CBCT reconstruction is the limited number of projections at each phase, which result in a reconstruction full of noise and streak artifacts with the conventional analytical algorithms. To address this problem, in this paper, we propose a motion compensated total variation regularization approach which tries to fully explore the temporal coherence of the spatial structures among the 4D-CBCT phases. In this work, we additionally conduct motion estimation/motion compensation (ME/MC) on the 4D-CBCT volume by using inter-phase deformation vector fields (DVFs). The motion compensated 4D-CBCT volume is then viewed as a pseudo-static sequence, of which the regularization function was imposed on. The regularization used in this work is the 3D spatial total variation minimization combined with 1D temporal total variation minimization. We subsequently construct a cost function for a reconstruction pass, and minimize this cost function using a variable splitting algorithm. Simulation and real patient data were used to evaluate the proposed algorithm. Results show that the introduction of additional temporal correlation along the phase direction can improve the 4D-CBCT image quality.

  17. Load and weather profile, and time simulation impacts for the PEPITE PV/H{sub 2} project

    Energy Technology Data Exchange (ETDEWEB)

    Darras, C.; Thibault, C.; Muselli, M.; Poggi, P. [University of Corsica, UMR CNRS SPE 6134, Route des Sanguinaires, F-20000 Ajaccio (France); Melscoet, S.; Hoguet, J.C. [HELION Hydrogen Power, Domaine du Petit Arbois - Batiment Jules Verne, BP 71, 13545 Aix en Provence (France); Pinton, E. [Commissariat a l' Energie Atomique (CEA/LITEN), 17 rue des Martyrs, 38 054 Grenoble Cedex 9 (France); Gailly, F.; Turpin, C. [Universite de Toulouse, INP, UPS, LAPLACE (Laboratoire Plasma et Conversion d' Energie), ENSEEIHT, 2 rue Charles Camichel, BP 7122, F-31071 Toulouse cedex 7 (France)

    2010-10-15

    This paper concerns the impacts of the meteorological data, the choice of the load profile, and the time simulation (1-11 years) on the energy flows and on the H{sub 2}/O{sub 2}/H{sub 2}O storage sizing in a photovoltaic/fuel cell/electrolyzer hybrid system (PEPITE project). The simulations were computed with the ORIENTE software. 4 load profiles have been investigated (3 diurnal and one nocturnal) with an identical daily consumption (26 kWh). According to load profiles, the gap observed between the most favorable and the most disadvantageous years induces H{sub 2} storage variations rates between 45.5% and 55.3%. Furthermore, if we compare the most penalizing meteorological year with the sizing when we simulate several successive years, we also obtain variation rates (ration between the standard deviation and the corresponding averaged value) ranges from 24.4 to 37.9% for the 3 diurnal profiles. The nocturnal profile presents specific results because it is unsustainable. The main conclusion of this work is the great importance to consider several consecutive years of tilted irradiation data, 7 in our case, to size the H{sub 2}/O{sub 2}/H{sub 2}O storages. (author)

  18. Electron-cloud simulation studies for the CERN-PS in the framework of the LHC Injectors Upgrade project

    CERN Document Server

    Rioja Fuentelsaz, Sergio

    The present study aims to provide a consistent picture of the electron cloud effect in the CERN Proton Synchrotron (PS) and to investigate possible future limitations due to the requirements foreseen by the LHC Injectors Upgrade (LIU) project. It consists of a complete simulation survey of the electron cloud build-up in the different beam pipe sections of the ring depending on several controllable beam parameters and vacuum chamber surface properties, covering present and future operation parameters. As the combined function magnets of the accelerator constitute almost the $80\\%$ in length of the ring, the implementation of a new feature for the simulation of any external magnetic field on the PyECLOUD code, made it possible to perform this study. All the results of the simulations are given as a function of the vacuum chamber surface properties in order to deduce them, both locally and globally, when compared with experimental data. In a first step, we characterize locally the maximum possible number of ...

  19. Gene therapy rescues cone function in congenital achromatopsia

    National Research Council Canada - National Science Library

    Komáromy, András M; Alexander, John J; Rowlan, Jessica S; Garcia, Monique M; Chiodo, Vince A; Kaya, Asli; Tanaka, Jacqueline C; Acland, Gregory M; Hauswirth, William W; Aguirre, Gustavo D

    2010-01-01

    .... We demonstrate that rAAV-mediated gene replacement therapy with different forms of the human red cone opsin promoter led to the restoration of cone function and day vision in two canine models...

  20. The WASCAL regional climate simulations for West Africa - how to add value to existing climate projections

    Science.gov (United States)

    Arnault, J.; Heinzeller, D.; Klein, C.; Dieng, D.; Smiatek, G.; Bliefernicht, J.; Sylla, M. B.; Kunstmann, H.

    2015-12-01

    With climate change being one of the most severe challenges to rural Africa in the 21st century, West Africa is facing an urgent need to develop effective adaptation and mitigation measures to protect its constantly growing population. WASCAL (West African Science Service Center on Climate Change and Adapted Land Use) is a large-scale research-focused program designed to enhance the resilience of human and environmental systems to climate change and increased variability. An integral part of its climate services is the provisioning of a new set of high resolution, ensemble-based regional climate change scenarios for the region of West Africa. In this contribution, we present the overall concept of the WASCAL regional climate projections and provide information on the dissemination of the data. We discuss the model performance over the validation period for two of the three regional climate models employed, the Weather Research & Forecasting Tool (WRF) and the Consortium for Small-scale Modeling Model COSMO in Climate Mode (COSMO-CLM), and give details about a novel precipitation database used to verify the models. Particular attention is paid to the representation of the dynamics of the West African Summer Monsoon and to the added value of our high resolution models over existing data sets. We further present results on the climate change signal obtained from the WRF model runs for the periods 2020-2050 and 2070-2100 and compare them to current state-of-the-art projections from the CORDEX project. As an example, the figure shows the different climate change signals obtained for the total annual rainfall with respect to the 1980-2010 mean (WRF-E: WASCAL 12km high-resolution run MPI-ESM + WRFV3.5.1, CORDEX-E: 50km medium-resolution run MPI-ESM + RCA4, CORDEX-G: 50km medium-resolution run GFDL-ESM + RCA4).

  1. UCSD Performance in the Edge Plasma Simulation (EPSI) Project. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Tynan, George Robert [Univ. of California, San Diego, CA (United States). Center for Energy Research

    2017-12-12

    This report contains a final report on the activities of UC San Diego PI G.R. Tynan and his collaborators as part of the EPSI Project, that was led by Dr. C.S. Chang, from PPPL. As a part of our work, we carried out several experiments on the ALCATOR C-­MOD tokamak device, aimed at unraveling the “trigger” or cause of the spontaneous transition from low-­mode confinement (L-­mode) to high confinement (H-­mode) that is universally observed in tokamak devices, and is planned for use in ITER.

  2. Simulation

    CERN Document Server

    Ross, Sheldon

    2006-01-01

    Ross's Simulation, Fourth Edition introduces aspiring and practicing actuaries, engineers, computer scientists and others to the practical aspects of constructing computerized simulation studies to analyze and interpret real phenomena. Readers learn to apply results of these analyses to problems in a wide variety of fields to obtain effective, accurate solutions and make predictions about future outcomes. This text explains how a computer can be used to generate random numbers, and how to use these random numbers to generate the behavior of a stochastic model over time. It presents the statist

  3. Field studies of beach cones as coastal erosion control/reversal devices for areas with significant oil and gas activities. Annual report, February 24, 1993--February 23, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Law, V.J.

    1994-07-07

    The primary objective of this project was to evaluate the utility of a device called the ``beach cone`` in combating coastal erosion. Seven initial sites were selected for testing beach cones in a variety of geometric configurations, and six sites were actually used. Six hundred beach cones were installed at the six sites in late July and early August, 1992. An additional 109 cones were installed at an eighth site in December of 1992. Findings indicate that beach cones accreted significant amounts of materials along the beach of a barrier island. At the eighth installation the amount of accreted material was measured by surveys to be 2200 cubic meters (2900 cubic yards) in February of 1993, when the cones were found to have been completely covered by the material. The average increase in elevation was about 7 inches (0. 18 in) with a maximum buildup of 3 ft. (I in). At other test sites, accretion rates have been less dramatic but importantly, no significant additional erosion has occurred, which is a positive result. The cost of sediment accretion using beach cones was found to be about $13.72 per cubic yard of sand or approximately $500,000 per mile of beach, which would be much lower if the cones were mass produced. The survival of the cones through the fringes of Hurricane Andrew indicates that they can be anchored sufficiently to survive significant storms. The measurements of the cones settling rates indicate that this effect is negligible, does not hinder their effectiveness. We do not yet have sufficient data to state the categorical success of the beach cones, but results to date are encouraging.

  4. Main Results of Phase IV BEMUSE Project: Simulation of LBLOCA in an NPP

    Directory of Open Access Journals (Sweden)

    M. Pérez

    2010-01-01

    The paper presents the results of the calculations performed by participants and emphasizes its usefulness for future uncertainty evaluation, to be performed in next phase. The objectives of the activity are basically to simulate the LBLOCA reproducing the phenomena associated to the scenario and also to build a common, well-known, basis for the future comparison of uncertainty evaluation results among different methodologies and codes. The sensitivity calculations performed by participants are also presented. They allow studying the influence of different parameters such as material properties or initial and boundary conditions, upon the behaviour of the most relevant parameters related to the scenario.

  5. The Ohio River Valley CO2 Storage Project AEP Mountaineer Plant, West Virginia Numerical Simulation and Risk Assessment Report

    Energy Technology Data Exchange (ETDEWEB)

    Neeraj Gupta

    2008-03-31

    A series of numerical simulations of carbon dioxide (CO{sub 2}) injection were conducted as part of a program to assess the potential for geologic sequestration in deep geologic reservoirs (the Rose Run and Copper Ridge formations), at the American Electric Power (AEP) Mountaineer Power Plant outside of New Haven, West Virginia. The simulations were executed using the H{sub 2}O-CO{sub 2}-NaCl operational mode of the Subsurface Transport Over Multiple Phases (STOMP) simulator (White and Oostrom, 2006). The objective of the Rose Run formation modeling was to predict CO{sub 2} injection rates using data from the core analysis conducted on the samples. A systematic screening procedure was applied to the Ohio River Valley CO{sub 2} storage site utilizing the Features, Elements, and Processes (FEP) database for geological storage of CO{sub 2} (Savage et al., 2004). The objective of the screening was to identify potential risk categories for the long-term geological storage of CO{sub 2} at the Mountaineer Power Plant in New Haven, West Virginia. Over 130 FEPs in seven main classes were assessed for the project based on site characterization information gathered in a geological background study, testing in a deep well drilled on the site, and general site conditions. In evaluating the database, it was apparent that many of the items were not applicable to the Mountaineer site based its geologic framework and environmental setting. Nine FEPs were identified for further consideration for the site. These FEPs generally fell into categories related to variations in subsurface geology, well completion materials, and the behavior of CO{sub 2} in the subsurface. Results from the screening were used to provide guidance on injection system design, developing a monitoring program, performing reservoir simulations, and other risk assessment efforts. Initial work indicates that the significant FEPs may be accounted for by focusing the storage program on these potential issues. The

  6. Hollow-Cone Spray Modeling for Outwardly Opening Piezoelectric Injector

    KAUST Repository

    Sim, Jaeheon

    2016-01-04

    Linear instability sheet atomization (LISA) breakup model has been widely used for modeling hollow-cone spray. However, the model was originally developed for inwardlyopening pressure-swirl injectors by assuming toroidal ligament breakups. Therefore, LISA model is not suitable for simulating outwardly opening injectors having string-like structures at wide spray angles. Furthermore, the varying area and shape of the annular nozzle exit makes the modeling difficult. In this study, a new spray modeling was proposed for outwardly opening hollow-cone injector. The injection velocities are computed from the given mas flow rate and injection pressure regardless of ambiguous nozzle exit geometries. The modified Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) breakup model is used with adjusted initial Sauter mean diameter (SMD) for modeling breakup of string-like liquid film spray. Liquid spray injection was modeled using Lagrangian discrete parcel method within the framework of commercial CFD software CONVERGE, and the detailed model was implemented by user defined functions. It was found that the new model predicted the liquid penetration length and local SMD accurately for various fuels and chamber conditions.

  7. ACCRETION OF SUPERSONIC WINDS ONTO BLACK HOLES IN 3D: STABILITY OF THE SHOCK CONE

    Energy Technology Data Exchange (ETDEWEB)

    Gracia-Linares, M.; Guzmán, F. S. [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo. Edificio C-3, Cd. Universitaria, 58040 Morelia, Michoacán, México (Mexico)

    2015-10-10

    Using numerical simulations we present the accretion of supersonic winds onto a rotating black hole in three dimensions. We study five representative directions of the wind with respect to the axis of rotation of the black hole and focus on the evolution and stability of the high-density shock cone that is formed during the process. We explore both the regime in which the shock cone is expected to be stable in order to confirm previous results obtained with two-dimensional simulations, and the regime in which the shock cone is expected to show a flip–flop (FF) type of instability. The methods used to attempt a triggering of the instability were (i) the accumulation of numerical errors and (ii) the explicit application of a perturbation on the velocity field after the shock cone was formed. The result is negative, that is, we did not find the FF instability within the parameter space we explored, including cases that are expected to be unstable.

  8. The Italian Project S2 - Task 4:Near-fault earthquake ground motion simulation in the Sulmona alluvial basin

    Science.gov (United States)

    Stupazzini, M.; Smerzini, C.; Cauzzi, C.; Faccioli, E.; Galadini, F.; Gori, S.

    2009-04-01

    Recently the Italian Department of Civil Protection (DPC), in cooperation with Istituto Nazionale di Geofisica e Vulcanologia (INGV) has promoted the 'S2' research project (http://nuovoprogettoesse2.stru.polimi.it/) aimed at the design, testing and application of an open-source code for seismic hazard assessment (SHA). The tool envisaged will likely differ in several important respects from an existing international initiative (Open SHA, Field et al., 2003). In particular, while "the OpenSHA collaboration model envisions scientists developing their own attenuation relationships and earthquake rupture forecasts, which they will deploy and maintain in their own systems", the main purpose of S2 project is to provide a flexible computational tool for SHA, primarily suited for the needs of DPC, which not necessarily are scientific needs. Within S2, a crucial issue is to make alternative approaches available to quantify the ground motion, with emphasis on the near field region. The SHA architecture envisaged will allow for the use of ground motion descriptions other than those yielded by empirical attenuation equations, for instance user generated motions provided by deterministic source and wave propagation simulations. In this contribution, after a brief presentation of Project S2, we intend to illustrate some preliminary 3D scenario simulations performed in the alluvial basin of Sulmona (Central Italy), as an example of the type of descriptions that can be handled in the future SHA architecture. In detail, we selected some seismogenic sources (from the DISS database), believed to be responsible for a number of destructive historical earthquakes, and derive from them a family of simplified geometrical and mechanical source models spanning across a reasonable range of parameters, so that the extent of the main uncertainties can be covered. Then, purely deterministic (for frequencies Journal of Seismology, 1, 237-251. Field, E.H., T.H. Jordan, and C.A. Cornell (2003

  9. Closed graph and open mapping theorems for normed cones

    Indian Academy of Sciences (India)

    A quasi-normed cone is a pair (, ) such that is a (not necessarily cancellative) cone and is a quasi-norm on . The aim of this paper is to prove a closed graph and an open mapping type theorem for quasi-normed cones. This is done with the help of appropriate notions of completeness, continuity and openness that ...

  10. Cones and craters on Mount Pavagadh, Deccan Traps: Rootless ...

    Indian Academy of Sciences (India)

    Rootless cones, also (erroneously) called pseudocraters, form due to explosions that ensue when a lava flow enters a surface water body, ice, or wet ground. They do not represent primary vents connected by vertical conduits to a subsurface magma source. Rootless cones in Iceland are well studied. Cones on Mars ...

  11. Comparative analysis between mandibular positions in centric relation and maximum intercuspation by cone beam computed tomography (CONE-BEAM)

    National Research Council Canada - National Science Library

    Ferreira, Amanda de Freitas; Henriques, João César Guimarães; Almeida, Guilherme Araújo; Machado, Asbel Rodrigues; Machado, Naila Aparecida de Godoi; Fernandes Neto, Alfredo Júlio

    2009-01-01

    ...) and maximum intercuspation (MI), using computed tomography volumetric cone beam (cone beam method). The sample of the study consisted of 10 asymptomatic young adult patients divided into two types of standard occlusion...

  12. Hyperkahler cones and orthogonal Wolf spaces

    NARCIS (Netherlands)

    Anguelova, L.K.; Rocek, M.; Vandoren, S.

    2002-01-01

    We construct the hyperk¨ahler cones corresponding to the quaternion-K¨ahler orthogonal Wolf spaces SO(n+4)/ SO(n)×SO(4) and their non-compact versions, which appear in hypermultiplet couplings to N = 2 supergravity. The geometry is completely encoded by a single function, the hyperk¨ahler

  13. Cone beam computed tomography in veterinary dentistry

    NARCIS (Netherlands)

    van Thielen, B.; Siguenza, F.; Hassan, B.

    2012-01-01

    The purpose of this study was to assess the feasibility of cone beam computed tomography (CBCT) in imaging dogs and cats for diagnostic dental veterinary applications. CBCT scans of heads of six dogs and two cats were made. Dental panoramic and multi-planar reformatted (MPR) para-sagittal

  14. Chloride equilibrium potential in salamander cones

    Directory of Open Access Journals (Sweden)

    Bryson Eric J

    2004-12-01

    Full Text Available Abstract Background GABAergic inhibition and effects of intracellular chloride ions on calcium channel activity have been proposed to regulate neurotransmission from photoreceptors. To assess the impact of these and other chloride-dependent mechanisms on release from cones, the chloride equilibrium potential (ECl was determined in red-sensitive, large single cones from the tiger salamander retinal slice. Results Whole cell recordings were done using gramicidin perforated patch techniques to maintain endogenous Cl- levels. Membrane potentials were corrected for liquid junction potentials. Cone resting potentials were found to average -46 mV. To measure ECl, we applied long depolarizing steps to activate the calcium-activated chloride current (ICl(Ca and then determined the reversal potential for the current component that was inhibited by the Cl- channel blocker, niflumic acid. With this method, ECl was found to average -46 mV. In a complementary approach, we used a Cl-sensitive dye, MEQ, to measure the Cl- flux produced by depolarization with elevated concentrations of K+. The membrane potentials produced by the various high K+ solutions were measured in separate current clamp experiments. Consistent with electrophysiological experiments, MEQ fluorescence measurements indicated that ECl was below -36 mV. Conclusions The results of this study indicate that ECl is close to the dark resting potential. This will minimize the impact of chloride-dependent presynaptic mechanisms in cone terminals involving GABAa receptors, glutamate transporters and ICl(Ca.

  15. Analog Experiment for rootless cone eruption

    Science.gov (United States)

    Noguchi, R.; Hamada, A.; Suzuki, A.; Kurita, K.

    2017-09-01

    Rootless cone is a unique geomorphological landmark to specify igneous origin of investigated terrane, which is formed by magma-water interaction. To understand its formation mechanism we conducted analog experiment for heat-induced vesiculation by using hot syrup and sodium bicarbonate solution.

  16. Lagrangian duality and cone convexlike functions

    NARCIS (Netherlands)

    J.B.G. Frenk (Hans); G. Kassay

    2005-01-01

    textabstractIn this paper we will show that the closely K-convexlike vector-valued functions with K Rm a nonempty convex cone and related classes of vector-valued functions discussed in the literature arise naturally within the theory of biconjugate functions applied to the Lagrangian perturbation

  17. Project SPECTRA! Using computer simulations to introduce spectroscopy to middle and high school students

    Science.gov (United States)

    Marks, N.; Wood, E. L.

    2009-12-01

    How do we gain information about the Sun? How do we know Mars has CO2 or that Titan has a nitrogen rich atmosphere? How do we use light in astronomy? Project SPECTRA!, a science and engineering program, uses computer-based Flash interactives to expose students to astronomical spectroscopy in a way that is not possible with traditional in-class activities. In the program, students are given a mission. Missions range from exploring remote planetary atmospheres and surfaces, experimenting with the Sun using different filters, and comparing spectroscopic atmospheric features between different bodies. Additionally, students have an opportunity to learn about different space missions, view movies, and see images connected with their mission. In the end, students are asked critical thinking questions and conduct web-based research. These interactives complement the in-class activities where students engineer spectrographs and explore the electromagnetic spectrum.

  18. Effects of the Cone and Edge on the Acoustic Characteristics of a Cone Loudspeaker

    Directory of Open Access Journals (Sweden)

    Yue Hu

    2017-01-01

    Full Text Available Loudspeakers are designed for reproducing the original sound field as faithfully as possible. In order to faithfully reproduce sound, it is important to understand the relationships among the physical characteristics of the loudspeaker. This paper focuses on the cone, the edge, and the behavior of air around the voice coil, which are important elements in the design of cone loudspeakers and evaluates their effects on the acoustic characteristics of the loudspeaker.

  19. Simulink library project for modeling and simulation of dynamic phenomena in rotating power transmission systems

    Directory of Open Access Journals (Sweden)

    Tomasz MATYJA

    2014-06-01

    Full Text Available This paper presents the concept and an example of usage of Simulink blocks library with which dynamic simulation of complex systems with rotating shafts, rigid rotors, bearings and couplings, general rotating power transmission systems of any configuration can be performed. The assumption is that library is modular and expandable. The main part of the library currently being developed is rigid rotor model with 6 degrees of freedom of the static and dynamic imbalance. Other components are: block modeling the bearing with mounting stiffness, damping and inertia; linear elastic-damping element and rigid beam finite element (RFEM. Also in preparation are: block modeling shaft with Timoshenko beam elements and Rayleigh damping, block modeling clutch.

  20. Projected bounds on ALP-photon coupling from simulated ATHENA data

    Science.gov (United States)

    Jennings, N.; Day, F.; Conlon, J.; Muia, F.; Krippendorf, S.

    2017-10-01

    ALPs (Axion-Like Particles) are light pseudo-scalars that are a well motivated extension of the Standard Model. These particles couple to photons in the presence of a magnetic field, and ultralight ALPs are converted particularly efficiently in galaxy clusters. At X-ray energies this coupling will induce quasi-sinusoidal oscillations in the spectrum of any object in or behind the cluster, allowing us to place bounds on this interaction from observations of AGNs in galaxy clusters. The X-IFU instrument on ATHENA will represent a huge leap forward in our ability to constrain ALP-photon interactions in this way, due to its predicted energy resolution of 2.5 eV. In this talk I will present bounds derived from simulated Athena data and discuss how different design configurations will affect these bounds.

  1. Interferometry of a reflective axicon surface with a small cone angle using an optical inner surface

    Science.gov (United States)

    Gao, Huimin; Zhang, Xiaodong; Fang, Fengzhou

    2017-09-01

    Reflective axicons, widely used in optical alignment and Bessel-Gauss beam generation, require a highly accurate cone angle and surface metrology. However, current methods focus on the cone angle measurement and it is still difficult to measure the surface of a reflective axicon with a small cone angle. An interferometer measurement method using an optical inner surface is proposed to obtain the surface and cone angle simultaneously. The optical axis of the axicon and the optical inner surface should align together and be parallel to the beam light from the interferometer. The interference fringe would be obtained by the optical system consisting of the axicon and the optical inner surface. The theoretical model is established and analyzed through ray tracing theory, and is verified by optical simulation software. Fabrication errors in the axicon and the inner surface, and misalignment of the measurement setup are investigated systematically and separated in the measurement process. In the experiments, the reflective axicon with a cone angle of about 90° was measured by the proposed method, the results of which show good agreement with a stylus profiler (Taylor-Hobson PGI 3D) in cone angle trend and generatrix error. Experimental results prove the feasibility of the proposed method. This economical and effective method can be widely used with all types of reflective axicons, and it can obtain the surface error map of the axicon as well as the inner cylinder at the same time. The uncertainty and resolution of the proposed method is based on the performance of the interferometer. The uncertainty of alignment angle errors is less than 10-10 rad; the lateral resolution is 53.8 µm.

  2. Perturbation theory in light-cone quantization

    Energy Technology Data Exchange (ETDEWEB)

    Langnau, Alex [Stanford Univ., CA (United States)

    1992-01-01

    A thorough investigation of light-cone properties which are characteristic for higher dimensions is very important. The easiest way of addressing these issues is by analyzing the perturbative structure of light-cone field theories first. Perturbative studies cannot be substituted for an analysis of problems related to a nonperturbative approach. However, in order to lay down groundwork for upcoming nonperturbative studies, it is indispensable to validate the renormalization methods at the perturbative level, i.e., to gain control over the perturbative treatment first. A clear understanding of divergences in perturbation theory, as well as their numerical treatment, is a necessary first step towards formulating such a program. The first objective of this dissertation is to clarify this issue, at least in second and fourth-order in perturbation theory. The work in this dissertation can provide guidance for the choice of counterterms in Discrete Light-Cone Quantization or the Tamm-Dancoff approach. A second objective of this work is the study of light-cone perturbation theory as a competitive tool for conducting perturbative Feynman diagram calculations. Feynman perturbation theory has become the most practical tool for computing cross sections in high energy physics and other physical properties of field theory. Although this standard covariant method has been applied to a great range of problems, computations beyond one-loop corrections are very difficult. Because of the algebraic complexity of the Feynman calculations in higher-order perturbation theory, it is desirable to automatize Feynman diagram calculations so that algebraic manipulation programs can carry out almost the entire calculation. This thesis presents a step in this direction. The technique we are elaborating on here is known as light-cone perturbation theory.

  3. Genetic heterogeneity among blue-cone monochromats

    Energy Technology Data Exchange (ETDEWEB)

    Nathans, J.; Maumenee, I.H.; Zrenner, E.; Sadowski, B.; Sharpe, L.T.; Lewis, R.A.; Hansen, E.; Rosenberg, T.; Schwartz, M.; Heckenlively, J.R.; Traboulsi, E.; Klingaman, R.; Bech-Hansen, N.T.; LaRoche, G.R.; Pagon, R.A.; Murphey, W.H.; Weleber, R.G.

    1993-11-01

    Thirty-three unrelated subjects with blue-cone monochromacy or closely related variants of blue-cone monochromacy were examined for rearrangements in the tandem array of genes encoding the red- and green-cone pigments. In 24 subjects, eight genotypes were found that would be predicted to eliminate the function of all of the genes within the array. As observed in an earlier study, the rearrangements involve either deletion of a locus control region adjacent to the gene array or loss of function via homologous recombination and point mutation. One inactivating mutation, Cy[sup 203]-to-Arg, was found in 15 probands who carry single genes and in both visual pigment genes in one subject whose array has two genes. This mutation was also found in at least one of the visual pigment genes in one subject whose array has multiple genes and in 2 of 321 control subjects, suggesting that preexisting Cys[sup 203]-to-Arg mutations constitute a reservoir of chromosomes that are predisposed to generate blue-cone-monochromat genotypes by unequal homologous recombination and/or gene conversion. Two other point mutations were identified: (a) Arg[sup 247]-to-Ter in one subject with a single red-pigment gene and (b) Pro[sup 307]-to-Leu in one subject with a single 5[prime] red-3[prime] green hybrid gene. The observed heterogeneity of genotypes points to the existence of multiple one- and two-step mutational pathways to blue-cone monochromacy. 28 refs., 9 figs., 2 tabs.

  4. Reconstructing images from projections using the maximum-entropy method. Numerical simulations of low-aspect astrotomography

    Science.gov (United States)

    Baikova, A. T.

    2007-11-01

    The reconstruction of images from a small number of projections using the maximum-entropy method (MEM) with the Shannon entropy is considered. MEM provides higher-quality image reconstruction for sources with extended components than the Högbom CLEAN method, which is also used in low-aspect astrotomography. The quality of image reconstruction for sources with mixed structure containing bright, compact features embedded in a comparatively weak, extended base can be further improved using a difference-mapping method, which requires a generalization of MEM for the reconstruction of sign-variable functions. We draw conclusions based on the results of numerical simulations for a number of model radio sources with various morphologies.

  5. Use of Generalized Fluid System Simulation Program (GFSSP) for Teaching and Performing Senior Design Projects at the Educational Institutions

    Science.gov (United States)

    Majumdar, A. K.; Hedayat, A.

    2015-01-01

    This paper describes the experience of the authors in using the Generalized Fluid System Simulation Program (GFSSP) in teaching Design of Thermal Systems class at University of Alabama in Huntsville. GFSSP is a finite volume based thermo-fluid system network analysis code, developed at NASA/Marshall Space Flight Center, and is extensively used in NASA, Department of Defense, and aerospace industries for propulsion system design, analysis, and performance evaluation. The educational version of GFSSP is freely available to all US higher education institutions. The main purpose of the paper is to illustrate the utilization of this user-friendly code for the thermal systems design and fluid engineering courses and to encourage the instructors to utilize the code for the class assignments as well as senior design projects.

  6. Aerodynamic performance of osculating-cones waveriders at high altitudes

    Science.gov (United States)

    Graves, Rick Evan

    The steady-state aerodynamic characteristics of three-dimensional waverider configurations immersed in hypersonic rarefied flows are investigated. Representative geometries are generated using an inverse design procedure, the method of osculating cones, which defines an exit plane shock shape and approximates the flow properties of the compression surface by assuming that each spanwise station along the shock profile lies within a region of locally conical flow. Vehicle surface and flow field properties are predicted using the direct simulation Monte Carlo method, a probabilistic numerical scheme in which simulated molecules are followed through representative collisions with each other and solid surfaces, and subsequent deterministic displacement. The aerodynamic properties of high- and low-Reynolds number waverider geometries, optimized for maximum lift-to-drag ratio and subject to mission-oriented constraints, are contrasted with results from reference caret and delta wings with similar internal volumes to quantify the relevance and advantage of the waverider concept at high altitudes. The high-Reynolds number waverider, optimized for the continuum regime at Minfinity = 4 and Reinfinity = 250 million, was the focus of recent wind tunnel testing for near on-design and off-design conditions, including low subsonic speeds. The present work extends the previous analyses into the high-altitude regime. The low-Reynolds number waverider, optimized at Minfinity = 20 and Reinfinity = 2.5 million, is studied to determine if optimization potential exists for a high-Mach number waverider at high altitudes. A characteristic length of 5 m is assumed for both waverider configurations, representative of a hypersonic missile concept. The geometries are aerodynamically evaluated over a parametric space consisting of an altitude variation of 95 km to 150 km and an angle of attack range of --5° to 10°. The effect of off-design Mach number on the performance of the high

  7. On multivalued contractions in cone metric spaces without normality.

    Science.gov (United States)

    Arshad, Muhammad; Ahmad, Jamshaid

    2013-01-01

    Wardowski (2011) in this paper for a normal cone metric space (X, d) and for the family A of subsets of X established a new cone metric H : A × A → E and obtained fixed point of set-valued contraction of Nadler type. Further, it is noticed in the work of Janković et al., 2011 that the fixed-point problem in the setting of cone metric spaces is appropriate only in the case when the underlying cone is nonnormal. In the present paper we improve Wardowski's result by proving the same without the assumption of normality on cones.

  8. Teaching Sustainable Design Using BIM and Project-Based Energy Simulations

    Directory of Open Access Journals (Sweden)

    Zhigang Shen

    2012-08-01

    Full Text Available The cross-disciplinary nature of energy-efficient building design has created many challenges for architecture, engineering and construction instructors. One of the technical challenges in teaching sustainable building design is enabling students to quantitatively understand how different building designs affect a building’s energy performance. Concept based instructional methods fall short in evaluating the impact of different design choices on a buildings’ energy consumption. Building Information Modeling (BIM with energy performance software provides a feasible tool to evaluate building design parameters. One notable advantage of this tool is its ability to couple 3D visualization of the structure with energy performance analysis without requiring detailed mathematical and thermodynamic calculations. Project-based Learning (PBL utilizing BIM tools coupled with energy analysis software was incorporated into a senior level undergraduate class. Student perceptions and feedback were analyzed to gauge the effectiveness of these techniques as instructional tools. The findings indicated that BIM-PBL can be used to effectively teach energy-efficient building design and construction.

  9. Characterization of projected DWPF glasses heat treated to simulate canister centerline cooling. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Marra, S.L.; Jantzen, C.M.

    1993-06-01

    Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. The glass will be produced and poured into stainless steel canisters in the Defense Waste Processing Facility (DWPF). Eventually these canistered waste forms will be sent to a geologic repository for final disposal. In order to assure acceptability by the repository, the Department of Energy has defined requirements which DWPF canistered waste forms must meet. These requirements are the Waste Acceptance Product Specifications (WAPS). The WAPS require DWPF to identify the crystalline phases expected to be present in the final glass product. Knowledge of the thermal history of the borosilicate glass during filling and cooldown of the canister is necessary to determine the amount and type of crystalline phases present in the final glass product. Glass samples of seven projected DWPF compositions were cooled following the same temperature profile as that of glass at the centerline of the full scale DWPF canister. The glasses were characterized by X-ray diffraction and scanning electron microscopy to identify the crystalline phases present. The volume percents of each crystalline phase present were determined by quantitative x-ray diffraction. The Product Consistency Test (PCT) was used to determine the durability of the heat treated glasses.

  10. Characterization of projected DWPF glasses heat treated to simulate canister centerline cooling

    Energy Technology Data Exchange (ETDEWEB)

    Marra, S.L.; Jantzen, C.M.

    1992-05-01

    Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. The glass will be produced and poured into stainless steel canisters in the Defense Waste Processing Facility (DWPF). Eventually these canistered waste forms will be sent to a geologic repository for final disposal. In order to assure acceptability by the repository, the Department of Energy has defined requirements which DWPF canistered waste forms must meet. These requirements are the Waste Acceptance Preliminary Specifications (WAPS). The WAPS require DWPF to identify the crystalline phases expected to be present in the final glass product. Knowledge of the thermal history of the borosilicate glass during filling and cooldown of the canister is necessary to determine the amount and type of crystalline phases present in the final glass product. Glass samples of seven projected DWPF compositions were cooled following the same temperature profile as that of glass at the centerline of the full-scale DWPF canister. The glasses were characterized by x-ray diffraction and scanning electron microscopy to identify the crystalline phases present The volume percents of each crystalline phase present were determined by quantitative x-ray diffraction. The Product Consistency Test (PCI) was used to determine the durability of the heat-treated glasses.

  11. Projecting the land use changes in China for the next two decades using a dynamic simulation framework

    Science.gov (United States)

    Jiang, Qun'ou; Deng, Xiangzheng; Zhan, Jinyan; Liu, Xingquan

    2008-10-01

    The purpose of this paper is to illustrate a modelling framework to simulate large-scale land use changes, and its effect on the structural and functional diversity of the ecosystem and social-economy based on the remotely sensed digital images. The improved DLS model is developed with three scenarios in China from 2001 to 2020. The projection results show that obvious land use changes will take place in the forestry area, grassland, cultivated land and unused land. Dramatic changes will appear in Cultivated area in Northeast China, Huang-Huai-Hai plain and Southwest China. The changes of forestry area are characterized by regional diversification. Grassland decreases mainly along the Great Wall of Inner Mongolia and on Tibets Plateau. The newly expanded urban land, comparably smaller, distributes mainly around the old towns or residential centers. There is no obvious change in water area. The unused area shrinks with the expansion of forest and grass area in Western China. Based on this study, the capability of improved DLS modelling framework in projecting the LUCC scenarios was tested successfully, and a conclusion was made that DLS model is an useful model in scenario construction.

  12. Self-calibration of vision parameters via genetic algorithms with simulated binary crossover and laser line projection

    Science.gov (United States)

    Alanís, Francisco Carlos Mejía; Rodríguez, J. Apolinar Muñoz

    2015-05-01

    A self-calibration technique based on genetic algorithms (GAs) with simulated binary crossover (SBX) and laser line imaging is presented. In this technique, the GA determines the vision parameters based on perspective projection geometry. The GA is constructed by means of an objective function, which is deduced from the equations of the laser line projection. To minimize the objective function, the GA performs a recombination of chromosomes through the SBX. This procedure provides the vision parameters, which are represented as chromosomes. The approach of the proposed GA is to achieve calibration and recalibration without external references and physical measurements. Thus, limitations caused by the missing of references are overcome to make self-calibration and three-dimensional (3-D) vision. Therefore, the proposed technique improves the self-calibration obtained by GAs with references. Additionally, 3-D vision is carried out via laser line position and vision parameters. The contribution of the proposed method is elucidated based on the accuracy of the self-calibration, which is performed with GAs.

  13. Mathematical Modelling of Fluid Flow in Cone and Cavitation Formation

    Directory of Open Access Journals (Sweden)

    Milada KOZUBKOVÁ

    2011-06-01

    Full Text Available Problem of cavitation is the undesirable phenomena occuring in the fluid flow in many hydraulic application (pumps, turbines, valves, etc.. Therefore this is in the focus of interest using experimental and mathematical methods. Based on cavitation modelling in Laval nozzle results and experience [1], [2], [4], following problem described as the water flow at the outlet from turbine blade wheel was solved. Primarily the problem is simplified into modelling of water flow in cone. Profiles of axial, radial and tangential velocity are defined on inlet zone. The value of pressure is defined on the outlet. Boundary conditions were defined by main investigator of the grant project – Energy Institute, Victor Kaplan’s Department of Fluid Engineering, Faculty of Mechanical Engineering, Brno University of Technology. The value of air volume was insignificant. Cavitation was solved by Singhal model of cavitation.

  14. Exact Interior Reconstruction with Cone-Beam CT

    Directory of Open Access Journals (Sweden)

    Yangbo Ye

    2007-01-01

    Full Text Available Using the backprojection filtration (BPF and filtered backprojection (FBP approaches, respectively, we prove that with cone-beam CT the interior problem can be exactly solved by analytic continuation. The prior knowledge we assume is that a volume of interest (VOI in an object to be reconstructed is known in a subregion of the VOI. Our derivations are based on the so-called generalized PI-segment (chord. The available projection onto convex set (POCS algorithm and singular value decomposition (SVD method can be applied to perform the exact interior reconstruction. These results have many implications in the CT field and can be extended to other tomographic modalities, such as SPECT/PET, MRI.

  15. Cone beam computed tomography: A boon for maxillofacial imaging

    Directory of Open Access Journals (Sweden)

    Sreenivas Rao Ghali

    2017-01-01

    Full Text Available In day to day practice, the radiographic techniques used individually or in combination suffer from some inherent limits of all planar two-dimensional (2D projections such as magnification, distortion, superimposition, and misrepresentation of anatomic structures. The introduction of cone-beam computed tomography (CBCT, specifically dedicated to imaging the maxillofacial region, heralds a major shift from 2D to three-dimensional (3D approach. It provides a complete 3D view of the maxilla, mandible, teeth, and supporting structures with relatively high resolution allowing a more accurate diagnosis, treatment planning and monitoring, and analysis of outcomes than conventional 2D images, along with low radiation exposure to the patient. CBCT has opened up new vistas for the use of 3D imaging as a diagnostic and treatment planning tool in dentistry. This paper provides an overview of the imaging principles, underlying technology, dental applications, and in particular focuses on the emerging role of CBCT in dentistry.

  16. Simulation of thermal indoor climate in buildings by using human Projected Area Factors

    DEFF Research Database (Denmark)

    Christensen, Jørgen Erik

    2009-01-01

    Nowadays many new and old buildings in Denmark have large glass surfaces. This is a consequence of the technical development of windows with low U-values that has made it possible to build houses with windows from floor to ceiling in northern climates. On the other hand if one is sitting close to...... for dynamic building thermal analysis. The method is demonstrated in a newer apartment with windows from floor to ceiling and shows how impotent it is to include the radiant effect from the glass sur-faces and how it influences the indoor thermal climate significantly.......Nowadays many new and old buildings in Denmark have large glass surfaces. This is a consequence of the technical development of windows with low U-values that has made it possible to build houses with windows from floor to ceiling in northern climates. On the other hand if one is sitting close...... to these large windows on a cold winter day it is recognized that this can cause thermal discomfort. The calculation of this discomfort needs to be taken properly into account in the simulation of the thermal indoor climate and energy consumption of the rooms. The operative temperature can be used as a simple...

  17. Satellite quenching time-scales in clusters from projected phase space measurements matched to simulated orbits

    Science.gov (United States)

    Oman, Kyle A.; Hudson, Michael J.

    2016-12-01

    We measure the star formation quenching efficiency and time-scale in cluster environments. Our method uses N-body simulations to estimate the probability distribution of possible orbits for a sample of observed Sloan Digital Sky Survey galaxies in and around clusters based on their position and velocity offsets from their host cluster. We study the relationship between their star formation rates and their likely orbital histories via a simple model in which star formation is quenched once a delay time after infall has elapsed. Our orbit library method is designed to isolate the environmental effect on the star formation rate due to a galaxy's present-day host cluster from `pre-processing' in previous group hosts. We find that quenching of satellite galaxies of all stellar masses in our sample (109-10^{11.5}M_{⊙}) by massive (> 10^{13} M_{⊙}) clusters is essentially 100 per cent efficient. Our fits show that all galaxies quench on their first infall, approximately at or within a Gyr of their first pericentric passage. There is little variation in the onset of quenching from galaxy-to-galaxy: the spread in this time is at most ˜2 Gyr at fixed M*. Higher mass satellites quench earlier, with very little dependence on host cluster mass in the range probed by our sample.

  18. Fostering interprofessional communication through case discussions and simulated ward rounds in nursing and medical education: A pilot project

    Directory of Open Access Journals (Sweden)

    Wershofen, Birgit

    2016-04-01

    Full Text Available Background: Poor communication between physicians and nursing staff could result in inadequate interprofessional collaboration with negative effects on patient health. In order to ensure optimal health care for patients, it is important to strengthen interprofessional communication and collaboration between physicians and nurses during their education. Aim: The aim of this project is to foster communication for medical and nursing students through interprofessional case discussions and simulated ward rounds as a form of training.Method: In 2013-15 a total of 39 nursing students and 22 medical students participated in eight seminars, each covering case discussions and simulated ward rounds. The seminar was evaluated based on student assessment of the educational objectives.Results: Students who voluntarily signed up for the seminar profited from the interprofessional interaction and gathered positive experiences working in a team.Conclusion: Through practicing case discussions and ward rounds as a group, interprofessional communication could be fostered between medical and nursing students. Students took advantage of the opportunity to ask those from other profession questions and realized that interprofessional interaction can lead to improved health care.

  19. The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): Overview and Description of Models, Simulations and Climate Diagnostics

    Science.gov (United States)

    Lamarque, J.-F.; Shindell, D. T.; Naik, V.; Plummer, D.; Josse, B.; Righi, M.; Rumbold, S. T.; Schulz, M.; Skeie, R. B.; Strode, S.; hide

    2013-01-01

    The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) consists of a series of time slice experiments targeting the long-term changes in atmospheric composition between 1850 and 2100, with the goal of documenting composition changes and the associated radiative forcing. In this overview paper, we introduce the ACCMIP activity, the various simulations performed (with a requested set of 14) and the associated model output. The 16 ACCMIP models have a wide range of horizontal and vertical resolutions, vertical extent, chemistry schemes and interaction with radiation and clouds. While anthropogenic and biomass burning emissions were specified for all time slices in the ACCMIP protocol, it is found that the natural emissions are responsible for a significant range across models, mostly in the case of ozone precursors. The analysis of selected present-day climate diagnostics (precipitation, temperature, specific humidity and zonal wind) reveals biases consistent with state-of-the-art climate models. The model-to- model comparison of changes in temperature, specific humidity and zonal wind between 1850 and 2000 and between 2000 and 2100 indicates mostly consistent results. However, models that are clear outliers are different enough from the other models to significantly affect their simulation of atmospheric chemistry.

  20. Cone-beam breast computed tomography with a displaced flat panel detector array

    Energy Technology Data Exchange (ETDEWEB)

    Mettivier, Giovanni; Russo, Paolo; Lanconelli, Nico; Meo, Sergio Lo [Universita di Napoli Federico II, Dipartimento di Scienze Fisiche, and INFN, Sezione di Napoli, I-80126 Napoli (Italy); Alma Mater Studiorum-Universita di Bologna, Dipartimento di Fisica, and INFN, Sezione di Bologna, I-40127 Bologna (Italy)

    2012-05-15

    Purpose: In cone-beam computed tomography (CBCT), and in particular in cone-beam breast computed tomography (CBBCT), an important issue is the reduction of the image artifacts produced by photon scatter and the reduction of patient dose. In this work, the authors propose to apply the detector displacement technique (also known as asymmetric detector or ''extended view'' geometry) to approach this goal. Potentially, this type of geometry, and the accompanying use of a beam collimator to mask the unirradiated half-object in each projection, permits some reduction of radiation dose with respect to conventional CBBCT and a sizeable reduction of the overall amount of scatter in the object, for a fixed contrast-to-noise ratio (CNR). Methods: The authors consider a scan configuration in which the projection data are acquired from an asymmetrically positioned detector that covers only one half of the scan field of view. Monte Carlo simulations and measurements, with their CBBCT laboratory scanner, were performed using PMMA phantoms of cylindrical (70-mm diameter) and hemiellipsoidal (140-mm diameter) shape simulating the average pendant breast, at 80 kVp. Image quality was evaluated in terms of contrast, noise, CNR, contrast-to-noise ratio per unit of dose (CNRD), and spatial resolution as width of line spread function for high contrast details. Results: Reconstructed images with the asymmetric detector technique deviate less than 1% from reconstruction with a conventional symmetric detector (detector view) and indicate a reduction of the cupping artifact in CT slices. The maximum scatter-to-primary ratio at the center of the phantom decreases by about 50% for both small and large diameter phantoms (e.g., from 0.75 in detector view to 0.40 in extended view geometry at the central axis of the 140-mm diameter PMMA phantom). Less cupping produces an increase of the CT number accuracy and an improved image detail contrast, but the associated increase of

  1. Feature Scaling via Second-Order Cone Programming

    Directory of Open Access Journals (Sweden)

    Zhizheng Liang

    2016-01-01

    Full Text Available Feature scaling has attracted considerable attention during the past several decades because of its important role in feature selection. In this paper, a novel algorithm for learning scaling factors of features is proposed. It first assigns a nonnegative scaling factor to each feature of data and then adopts a generalized performance measure to learn the optimal scaling factors. It is of interest to note that the proposed model can be transformed into a convex optimization problem: second-order cone programming (SOCP. Thus the scaling factors of features in our method are globally optimal in some sense. Several experiments on simulated data, UCI data sets, and the gene data set are conducted to demonstrate that the proposed method is more effective than previous methods.

  2. Accidental degeneracy of double Dirac cones in a phononic crystal

    KAUST Repository

    Chen, Ze-Guo

    2014-04-09

    Artificial honeycomb lattices with Dirac cone dispersion provide a macroscopic platform to study the massless Dirac quasiparticles and their novel geometric phases. In this paper, a quadruple-degenerate state is achieved at the center of the Brillouin zone in a two-dimensional honeycomb lattice phononic crystal, which is a result of accidental degeneracy of two double-degenerate states. In the vicinity of the quadruple-degenerate state, the dispersion relation is linear. Such quadruple degeneracy is analyzed by rigorous representation theory of groups. Using method, a reduced Hamiltonian is obtained to describe the linear Dirac dispersion relations of this quadruple-degenerate state, which is well consistent with the simulation results. Near such accidental degeneracy, we observe some unique properties in wave propagating, such as defect-insensitive propagating character and the Talbot effect.

  3. 3D dictionary learning based iterative cone beam CT reconstruction

    Directory of Open Access Journals (Sweden)

    Ti Bai

    2014-03-01

    Full Text Available Purpose: This work is to develop a 3D dictionary learning based cone beam CT (CBCT reconstruction algorithm on graphic processing units (GPU to improve the quality of sparse-view CBCT reconstruction with high efficiency. Methods: A 3D dictionary containing 256 small volumes (atoms of 3 × 3 × 3 was trained from a large number of blocks extracted from a high quality volume image. On the basis, we utilized cholesky decomposition based orthogonal matching pursuit algorithm to find the sparse representation of each block. To accelerate the time-consuming sparse coding in the 3D case, we implemented the sparse coding in a parallel fashion by taking advantage of the tremendous computational power of GPU. Conjugate gradient least square algorithm was adopted to minimize the data fidelity term. Evaluations are performed based on a head-neck patient case. FDK reconstruction with full dataset of 364 projections is used as the reference. We compared the proposed 3D dictionary learning based method with tight frame (TF by performing reconstructions on a subset data of 121 projections. Results: Compared to TF based CBCT reconstruction that shows good overall performance, our experiments indicated that 3D dictionary learning based CBCT reconstruction is able to recover finer structures, remove more streaking artifacts and also induce less blocky artifacts. Conclusion: 3D dictionary learning based CBCT reconstruction algorithm is able to sense the structural information while suppress the noise, and hence to achieve high quality reconstruction under the case of sparse view. The GPU realization of the whole algorithm offers a significant efficiency enhancement, making this algorithm more feasible for potential clinical application.-------------------------------Cite this article as: Bai T, Yan H, Shi F, Jia X, Lou Y, Xu Q, Jiang S, Mou X. 3D dictionary learning based iterative cone beam CT reconstruction. Int J Cancer Ther Oncol 2014; 2(2:020240. DOI: 10

  4. Cone damage in patients receiving high-dose irofulven treatment.

    Science.gov (United States)

    Lee, Michael S; Gupta, Nisha; Penson, Richard T; Loewenstein, John; Wepner, Meredith S; Seiden, Michael V; Milam, Ann H

    2005-01-01

    To describe the clinical, perimetric, and electroretinographic (ERG) results of 4 patients with cone dysfunction following irofulven treatment including the histopathologic and immunocytochemical features of one patient's retinas. Observational case series. The patients were examined clinically, including perimetric and ERG evaluations. Eyes from patient 1 and healthy postmortem eyes were processed for histopathologic and immunocytochemistry studies with antibodies specific for cones, rods, and reactive Müller cells. Clinical signs and symptoms, perimetry, ERG, retinal histopathologic and immunocytochemistry study results. All 4 patients had ERG changes consistent with abnormal cone responses and relatively normal rod responses. Compared with control eyes, the retina of patient 1 had approximately half the normal numbers of macular cones and fewer peripheral cones. The number of rods were normal but all rod and cone outer segments were shortened. High-dose irofulven treatment causes cone-specific damage with relative sparing of rods.

  5. A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dongxiao; Shan, Lianqiang; Zhou, Weimin; Wu, Yuchi; Zhu, Bin; Zhang, Feng; Bi, Bi; Zhang, Bo; Zhang, Zhimeng; Shui, Min; He, Yingling; Gu, Yuqiu, E-mail: yqgu@caep.cn; Zhang, Baohan [Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Peng, Xiaoshi; Xu, Tao; Wang, Feng; Yang, Zhiwen; Chen, Tao; Chen, Li; Chen, Ming [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); and others

    2016-06-15

    During fast-ignition implosions, preheating of inside the cone tip caused by hard X-rays can strongly affect the generation and transport of hot electrons in the cone. Although indirect-drive implosions have a higher implosion symmetry, they cause stronger preheating effects than direct-drive implosions. To control the preheating of the cone tip, we propose the use of indirect-drive fast-ignition targets with thicker tips. Experiments carried out at the ShenGuang-III prototype laser facility confirmed that thicker tips are effective for controlling preheating. Moreover, these results were consistent with those of 1D radiation hydrodynamic simulations.

  6. Natural gas markets integration in the Southern Cone: analysis of interests and stakeholders; Perspectivas para a integracao gasifera no Cone Sul: uma analise dos principais interesses e interessados

    Energy Technology Data Exchange (ETDEWEB)

    Villas Boas, Marina Vieira [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    Natural gas has been recently gaining importance in the world energy mix especially because of its economical and environmental advantages but also because of technological and geopolitical issues. In the Southern Cone, natural gas demand shall maintain its upward trend in the next years mainly due to its use in power generation. This region owns significant natural gas reserves and, at the same time, a growing and with high potential market. In this scenario, natural gas markets integration is seen simultaneously as an opportunity and a necessity as it can contribute to demand and production interconnection, price competitiveness and security of supply. Nevertheless, there are important barriers to the consolidation of natural gas market integration in the Southern Cone region that have to be overcome. For the natural gas markets integration to be a sustainable project it is necessary to identify the major stakeholders and their interests and pursue a balance between them. (author)

  7. Evaluation of the OSC-TV iterative reconstruction algorithm for cone-beam optical CT.

    Science.gov (United States)

    Matenine, Dmitri; Mascolo-Fortin, Julia; Goussard, Yves; Després, Philippe

    2015-11-01

    The present work evaluates an iterative reconstruction approach, namely, the ordered subsets convex (OSC) algorithm with regularization via total variation (TV) minimization in the field of cone-beam optical computed tomography (optical CT). One of the uses of optical CT is gel-based 3D dosimetry for radiation therapy, where it is employed to map dose distributions in radiosensitive gels. Model-based iterative reconstruction may improve optical CT image quality and contribute to a wider use of optical CT in clinical gel dosimetry. This algorithm was evaluated using experimental data acquired by a cone-beam optical CT system, as well as complementary numerical simulations. A fast GPU implementation of OSC-TV was used to achieve reconstruction times comparable to those of conventional filtered backprojection. Images obtained via OSC-TV were compared with the corresponding filtered backprojections. Spatial resolution and uniformity phantoms were scanned and respective reconstructions were subject to evaluation of the modulation transfer function, image uniformity, and accuracy. The artifacts due to refraction and total signal loss from opaque objects were also studied. The cone-beam optical CT data reconstructions showed that OSC-TV outperforms filtered backprojection in terms of image quality, thanks to a model-based simulation of the photon attenuation process. It was shown to significantly improve the image spatial resolution and reduce image noise. The accuracy of the estimation of linear attenuation coefficients remained similar to that obtained via filtered backprojection. Certain image artifacts due to opaque objects were reduced. Nevertheless, the common artifact due to the gel container walls could not be eliminated. The use of iterative reconstruction improves cone-beam optical CT image quality in many ways. The comparisons between OSC-TV and filtered backprojection presented in this paper demonstrate that OSC-TV can potentially improve the rendering of

  8. A method for weighted projections to the positive definite cone

    KAUST Repository

    Valkonen, Tuomo

    2014-06-24

    © 2014 Taylor & Francis. We study the numerical solution of the problem (Formula presented.) , where (Formula presented.) is a symmetric square matrix, and (Formula presented.) is a linear operator, such that (Formula presented.) is invertible. With (Formula presented.) the desired fractional duality gap, and (Formula presented.) the condition number of (Formula presented.) , we prove (Formula presented.) iteration complexity for a simple primal-dual interior point method directly based on those for linear programs with semi-definite constraints. We do not, however, require the numerically expensive scalings inherent in these methods to force fast convergence. For low-dimensional problems (Formula presented.), our numerical experiments indicate excellent performance and only a very slowly growing dependence of the convergence rate on (Formula presented.). While our algorithm requires somewhat more iterations than existing interior point methods, the iterations are cheaper. This gives better computational times.

  9. Lightweight Exit Cone for Liquid Rocket Engines Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Pratt and Whitney Rocketdyne (PWR) J-2X engine will power the upper stage of the Ares I and the earth departure stage (EDS) of the Ares V, which will enable...

  10. Analysis of New Aerodynamic Design of the Nose Cone Section Using CFD and SPH

    National Research Council Canada - National Science Library

    Bogdan-Alexandru, BELEGA

    2015-01-01

    .... The scope of this paper is to develop some prototype profiles with outstanding aerodynamic qualities and low cost for use in construction projects for missile increasing their range and effect on target. The motivation for such a work is caused by a lack of data on aerodynamics for profiles of some nose cones and especially improved aerodynamic qualities that can be used in designing missiles/rockets.

  11. A new method for x-ray scatter correction: first assessment on a cone-beam CT experimental setup

    Energy Technology Data Exchange (ETDEWEB)

    Rinkel, J [CEA-LETI MINATEC, Division of Micro Technologies for Biology and Healthcare, 38054 Grenoble Cedex 09 (France); Gerfault, L [CEA-LETI MINATEC, Division of Micro Technologies for Biology and Healthcare, 38054 Grenoble Cedex 09 (France); Esteve, F [INSERM U647-RSRM, ESRF, BP200, 38043 Grenoble Cedex 09 (France); Dinten, J-M [CEA-LETI MINATEC, Division of Micro Technologies for Biology and Healthcare, 38054 Grenoble Cedex 09 (France)

    2007-08-07

    Cone-beam computed tomography (CBCT) enables three-dimensional imaging with isotropic resolution and a shorter acquisition time compared to a helical CT scanner. Because a larger object volume is exposed for each projection, scatter levels are much higher than in collimated fan-beam systems, resulting in cupping artifacts, streaks and quantification inaccuracies. In this paper, a general method to correct for scatter in CBCT, without supplementary on-line acquisition, is presented. This method is based on scatter calibration through off-line acquisition combined with on-line analytical transformation based on physical equations, to adapt calibration to the object observed. The method was tested on a PMMA phantom and on an anthropomorphic thorax phantom. The results were validated by comparison to simulation for the PMMA phantom and by comparison to scans obtained on a commercial multi-slice CT scanner for the thorax phantom. Finally, the improvements achieved with the new method were compared to those obtained using a standard beam-stop method. The new method provided results that closely agreed with the simulation and with the conventional CT scanner, eliminating cupping artifacts and significantly improving quantification. Compared to the beam-stop method, lower x-ray doses and shorter acquisition times were needed, both divided by a factor of 9 for the same scatter estimation accuracy.

  12. Dirac cones in two-dimensional borane

    Science.gov (United States)

    Martinez-Canales, Miguel; Galeev, Timur R.; Boldyrev, Alexander I.; Pickard, Chris J.

    2017-11-01

    We introduce two-dimensional borane, a single-layered material of BH stoichiometry, with promising electronic properties. We show that, according to density functional theory calculations, two-dimensional borane is semimetallic, with two symmetry-related Dirac cones meeting right at the Fermi energy Ef. The curvature of the cones is lower than in graphene, thus closer to the ideal linear dispersion. Its structure, formed by a puckered trigonal boron network with hydrogen atoms connected to each boron atom, can be understood as distorted, hydrogenated borophene [Mannix et al., Science 350, 1513 (2015), 10.1126/science.aad1080]. Chemical bonding analysis reveals the boron layer in the network being bound by delocalized four-center two-electron σ bonds. Finally, we suggest high pressure could be a feasible route to synthesize two-dimensional borane.

  13. Brain perfusion imaging using a Reconstruction-of-Difference (RoD) approach for cone-beam computed tomography

    Science.gov (United States)

    Mow, M.; Zbijewski, W.; Sisniega, A.; Xu, J.; Dang, H.; Stayman, J. W.; Wang, X.; Foos, D. H.; Koliatsos, V.; Aygun, N.; Siewerdsen, J. H.

    2017-03-01

    Purpose: To improve the timely detection and treatment of intracranial hemorrhage or ischemic stroke, recent efforts include the development of cone-beam CT (CBCT) systems for perfusion imaging and new approaches to estimate perfusion parameters despite slow rotation speeds compared to multi-detector CT (MDCT) systems. This work describes development of a brain perfusion CBCT method using a reconstruction of difference (RoD) approach to enable perfusion imaging on a newly developed CBCT head scanner prototype. Methods: A new reconstruction approach using RoD with a penalized-likelihood framework was developed to image the temporal dynamics of vascular enhancement. A digital perfusion simulation was developed to give a realistic representation of brain anatomy, artifacts, noise, scanner characteristics, and hemo-dynamic properties. This simulation includes a digital brain phantom, time-attenuation curves and noise parameters, a novel forward projection method for improved computational efficiency, and perfusion parameter calculation. Results: Our results show the feasibility of estimating perfusion parameters from a set of images reconstructed from slow scans, sparse data sets, and arc length scans as short as 60 degrees. The RoD framework significantly reduces noise and time-varying artifacts from inconsistent projections. Proper regularization and the use of overlapping reconstructed arcs can potentially further decrease bias and increase temporal resolution, respectively. Conclusions: A digital brain perfusion simulation with RoD imaging approach has been developed and supports the feasibility of using a CBCT head scanner for perfusion imaging. Future work will include testing with data acquired using a 3D-printed perfusion phantom currently and translation to preclinical and clinical studies.

  14. Measurement of breast tissue composition with dual energy cone-beam computed tomography: A postmortem study

    Energy Technology Data Exchange (ETDEWEB)

    Ding Huanjun; Ducote, Justin L.; Molloi, Sabee [Department of Radiological Sciences, University of California, Irvine, California 92697 (United States)

    2013-06-15

    Purpose: To investigate the feasibility of a three-material compositional measurement of water, lipid, and protein content of breast tissue with dual kVp cone-beam computed tomography (CT) for diagnostic purposes. Methods: Simulations were performed on a flat panel-based computed tomography system with a dual kVp technique in order to guide the selection of experimental acquisition parameters. The expected errors induced by using the proposed calibration materials were also estimated by simulation. Twenty pairs of postmortem breast samples were imaged with a flat-panel based dual kVp cone-beam CT system, followed by image-based material decomposition using calibration data obtained from a three-material phantom consisting of water, vegetable oil, and polyoxymethylene plastic. The tissue samples were then chemically decomposed into their respective water, lipid, and protein contents after imaging to allow direct comparison with data from dual energy decomposition. Results: Guided by results from simulation, the beam energies for the dual kVp cone-beam CT system were selected to be 50 and 120 kVp with the mean glandular dose divided equally between each exposure. The simulation also suggested that the use of polyoxymethylene as the calibration material for the measurement of pure protein may introduce an error of -11.0%. However, the tissue decomposition experiments, which employed a calibration phantom made out of water, oil, and polyoxymethylene, exhibited strong correlation with data from the chemical analysis. The average root-mean-square percentage error for water, lipid, and protein contents was 3.58% as compared with chemical analysis. Conclusions: The results of this study suggest that the water, lipid, and protein contents can be accurately measured using dual kVp cone-beam CT. The tissue compositional information may improve the sensitivity and specificity for breast cancer diagnosis.

  15. Research of forming of thin-walled axisymmetric cone-shaped parts

    Science.gov (United States)

    Demyanenko, E. G.; Popov, I. P.; Abroyan, A. U.

    2017-10-01

    This article presents a new method based on the process of beading, which allows reducing polythickness of the part wall along generatrix. The proposed method differs from known approaches in the fact that it is presented active friction forces exerted on the both surfaces of the blank. These forces are provided by usage of the elastic die and cone. This method was researched using computer simulation andexperiment. In the experiment it was used the stamping tool, which implements the proposed method.

  16. Lessons from the light-cone box

    CERN Document Server

    Leibbrandt, G

    2000-01-01

    Working in the noncovariant light-cone gauge, we discuss the explicit computation of the 1PI four-point function ("box diagram") in Yang- Mills theory. The complete box diagram which consists of 16 box subdiagrams, 8 lynx subdiagrams and 4 fish subdiagrams, yields both local and nonlocal UV divergent terms. The nonlocal terms are consistent with gauge symmetry and correspond to a nonlocal renormalization of the wave function. (14 refs).

  17. Wide-Field Fundus Autofluorescence for Retinitis Pigmentosa and Cone/Cone-Rod Dystrophy.

    Science.gov (United States)

    Oishi, Akio; Oishi, Maho; Ogino, Ken; Morooka, Satoshi; Yoshimura, Nagahisa

    2016-01-01

    Retinitis pigmentosa and cone/cone-rod dystrophy are inherited retinal diseases characterized by the progressive loss of rod and/or cone photoreceptors. To evaluate the status of rod/cone photoreceptors and visual function, visual acuity and visual field tests, electroretinogram, and optical coherence tomography are typically used. In addition to these examinations, fundus autofluorescence (FAF) has recently garnered attention. FAF visualizes the intrinsic fluorescent material in the retina, which is mainly lipofuscin contained within the retinal pigment epithelium. While conventional devices offer limited viewing angles in FAF, the recently developed Optos machine enables recording of wide-field FAF. With wide-field analysis, an association between abnormal FAF areas and visual function was demonstrated in retinitis pigmentosa and cone-rod dystrophy. In addition, the presence of "patchy" hypoautofluorescent areas was found to be correlated with symptom duration. Although physicians should be cautious when interpreting wide-field FAF results because the peripheral parts of the image are magnified significantly, this examination method provides previously unavailable information.

  18. The NLO jet vertex in the small-cone approximation for kt and cone algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Colferai, D.; Niccoli, A. [Dipartimento di Fisica e Astronomia, Università di Firenze and INFN, Sezione di Firenze, 50019 Sesto Fiorentino (Italy)

    2015-04-15

    We determine the jet vertex for Mueller-Navelet jets and forward jets in the small-cone approximation for two particular choices of jet algoritms: the kt algorithm and the cone algorithm. These choices are motivated by the extensive use of such algorithms in the phenomenology of jets. The differences with the original calculations of the small-cone jet vertex by Ivanov and Papa, which is found to be equivalent to a formerly algorithm proposed by Furman, are shown at both analytic and numerical level, and turn out to be sizeable. A detailed numerical study of the error introduced by the small-cone approximation is also presented, for various observables of phenomenological interest. For values of the jet “radius” R=0.5, the use of the small-cone approximation amounts to an error of about 5% at the level of cross section, while it reduces to less than 2% for ratios of distributions such as those involved in the measure of the azimuthal decorrelation of dijets.

  19. A Coning Theory of Bullet Motions

    CERN Document Server

    Boatright, James A

    2012-01-01

    Each observable ballistic phenomenon of a spin-stabilized rifle bullet can be explained in terms of the acceleration of gravity and the total aerodynamic force acting on that bullet. In addition to the coning motion itself, Coning Theory explains the spinning bullet's aerodynamic jump and its steadily increasing yaw of repose together with its resulting spin-drift. The total aerodynamic force on the bullet comprises its drag and lift rectangular components and produces an associated overturning moment acting upon the rigid bullet. The coning motion of the bullet includes two distinct but synchronized aspects: 1) the well-known gyroscopic precession of the spin-axis of the bullet, and 2) the previously little-known orbiting of the center of gravity of the bullet around its mean trajectory with the nose of the bullet angled inward toward that trajectory. New equations are developed governing the orbital motion of the CG as a circular, isotropic harmonic oscillation driven by the lift and drag forces as they rev...

  20. Selection of topologies for the PHOTONERGY{sup TM} project, part 2. Simulation, selection and perspective of topologies

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-11-01

    The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into the specifications. Based on these two documents, a set of 23 topologies was analysed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies were in further investigated by means of an initial design-iteration and simulations. Based on the results achieved in, an updated document (this) is created. The items of interest in this report are efficiency and component ratings (magnetics, transistors, diodes and capacitors). The topologies investigated in this report are: the normal full bridge DC/DC converter, the MOHAN DC/DC converter, the normal full bridge DC/AC inverter, and the modified SHIMIZU DC/AC inverter. The simulations carried out in this report reveals that the efficiencies for the two DC/DC converters (together with the DC/AC inverter) are much similar to each other {approx} 72%. For that reason, none of them can be preferred above the other. On the other hand, when counting the components and estimating the cost for the two DC/DC converter, the standard full bridge DC/DC converter (cost: {approx} 197 DKk.) seems to be most advantageous that the MOHAN DC/DC converter (cost: {approx} 213 DKk.). The modified SHIMIZU inverter seems to be better, in terms of efficiency, than the two mentioned DC/DC converters together with the DC/AC inverter. During the design stage of this inverter, it emerged that the control circuit could be a limiting factor in terms of speed and accuracy. A deeper investigation should be carried out in order to state a more adequate conclusion about this novel inverter. The recommendation for the future is; to base the SolcelleInverter on the standard full bridge DC/DC converter together with the standard full bridge DC/AC inverter, and the modified SHIMIZU DC/AC inverter should also be further

  1. Collective effects in tilted Weyl cones: Optical conductivity, polarization, and Coulomb interactions reshaping the cone

    Science.gov (United States)

    Detassis, Fabrizio; Fritz, Lars; Grubinskas, Simonas

    2017-11-01

    Recently, the existence of Dirac/Weyl cones in three-dimensional systems has been demonstrated experimentally. While in high-energy physics the isotropy of the Dirac/Weyl cones is guaranteed by relativistic invariance, in condensed-matter systems corrections to this can occur, with one possible type being a tilt. In this paper, we study the effect of tilted Weyl cones in collective effects. We study both the optical conductivity as well as the polarization function. We also investigate the perturbative effect of long-range Coulomb interactions using a renormalization-group calculation. We find that the tilt is perturbatively renormalized towards zero and at low energies the system flows to an effectively untilted theory.

  2. Fast electron transport and spatial energy deposition in imploded fast ignition cone-in-shell targets

    Science.gov (United States)

    Jarrott, Leonard

    2014-10-01

    We report on the first experimental observation and model validation of the spatial energy deposition of fast electrons into the imploded, high-density core of integrated cone-in-shell fast ignition experiments on OMEGA. Spatial energy deposition was characterized via fast electron produced K α fluorescence from a Cu tracer added to the CD shell. 2-D images of the Cu K α fluorescence were obtained using a spherically bent Bragg crystal imager. 54 of the 60 OMEGA beams (18 kJ) were used for fuel assembly, and the high intensity EP beam (10 ps, 0.5--1.5 kJ, Ip >1019 W/cm2) , was focused onto the inner cone tip to produce fast electrons. Cu K α emission from a 300 μm region surrounding the cone tip correlated well with the predicted core size from radiation-hydrodynamic simulations of the shell implosion. The emission also emanated from as far back as 100 μm from the cone tip, indicative of an electron source position with a large standoff distance from the cone tip, consistent with the presence of an extended pre-plasma from the EP pre-pulse. We observed a simultaneous increase in both K α yield (up to 70%) and thermal neutron number (up to 2×) with increasing EP beam energy. K α yield data also show an improved energy coupling using the high contrast EP pulse. Comprehensive simulations of the electron production within the cone and subsequent transport into the imploded core have been performed using the implicit PIC code LSP and the hybrid-PIC code ZUMA. These simulations explain the observed K α shape and yield trends and identify parameters that constrain energy coupling into the compressed core. This work was performed under the auspices of U.S. DOE under Contracts DE-FC02-04ER54789 (FSC), DE-FG02-05ER54834 (ACE) and DE-NA0000854 (NLUF).

  3. Applying microCT and 3D Visualization to Jurassic Silicified Conifer Seed Cones: A Virtual Advantage Over Thin-Sectioning

    Directory of Open Access Journals (Sweden)

    Carole T. Gee

    2013-11-01

    Full Text Available Premise of the study: As an alternative to conventional thin-sectioning, which destroys fossil material, high-resolution X-ray computed tomography (also called microtomography or microCT integrated with scientific visualization, three-dimensional (3D image segmentation, size analysis, and computer animation is explored as a nondestructive method of imaging the internal anatomy of 150-million-year-old conifer seed cones from the Late Jurassic Morrison Formation, USA, and of recent and other fossil cones. Methods: MicroCT was carried out on cones using a General Electric phoenix v|tome|x s 240D, and resulting projections were processed with visualization software to produce image stacks of serial single sections for two-dimensional (2D visualization, 3D segmented reconstructions with targeted structures in color, and computer animations. Results: If preserved in differing densities, microCT produced images of internal fossil tissues that showed important characters such as seed phyllotaxy or number of seeds per cone scale. Color segmentation of deeply embedded seeds highlighted the arrangement of seeds in spirals. MicroCT of recent cones was even more effective. Conclusions: This is the first paper on microCT integrated with 3D segmentation and computer animation applied to silicified seed cones, which resulted in excellent 2D serial sections and segmented 3D reconstructions, revealing features requisite to cone identification and understanding of strobilus construction.

  4. Graduating dental students' ability to produce quality root canal fillings using single- or multiple-cone obturation techniques.

    Science.gov (United States)

    Gound, Tom G; Sather, James P; Kong, Tae S; Makkawy, Hany A; Marx, David B

    2009-06-01

    The primary purposes of this study were to compare the quality (length and density) and efficiency (time to completion) of obturation when single- or multiple-cone obturation techniques were used by graduating dental school students on previously instrumented single-canalled teeth using simulated clinical conditions in vitro. Five students took part in the study, each of whom obturated thirty-six teeth using six obturation techniques. The multiple-cone techniques included lateral condensation of gutta-percha, the technique the students had used in their laboratory and clinical courses, and two similar variations: lateral condensation of Epiphany and mechanical lateral condensation of gutta-percha. These three methods were compared to three single-cone techniques: Thermafil, Activ GP, and GuttaFlow. The students had no experience with single-cone techniques except for a brief introduction and demonstration. All obturations were timed, and post-obturation radiographs were taken in the clinical and proximal views (CV and PV). The radiographs were read by two endodontic faculty members who were blinded to technique, student, and fellow faculty member's results. Data were also separated by operator experience with individual techniques: the first three obturations/techniques were compared to the final three obturations/techniques. Data were analyzed using chi-square tests. The quality produced or time required rarely differed within multiple-cone or single-cone groups, but statistical differences did occur between the two groups. Multiple-cone obturation was more likely to produce adequate length (p=0.0042), density in the CV (p=0.0056), and density in the PV (p=0.0003). Conversely, the single-cone techniques were significantly faster (mean 350 seconds) than the multiple-cone techniques (mean 464 seconds) (p=0.0020). Quality did not improve significantly with the experienced groups versus the inexperienced with any of the six techniques, but the mean time for obturation

  5. A model-based scatter artifacts correction for cone beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Wei; Zhu, Jun; Wang, Luyao [Department of Biomedical Engineering, Huazhong University of Science and Technology, Hubei 430074 (China); Vernekohl, Don; Xing, Lei, E-mail: lei@stanford.edu [Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States)

    2016-04-15

    Purpose: Due to the increased axial coverage of multislice computed tomography (CT) and the introduction of flat detectors, the size of x-ray illumination fields has grown dramatically, causing an increase in scatter radiation. For CT imaging, scatter is a significant issue that introduces shading artifact, streaks, as well as reduced contrast and Hounsfield Units (HU) accuracy. The purpose of this work is to provide a fast and accurate scatter artifacts correction algorithm for cone beam CT (CBCT) imaging. Methods: The method starts with an estimation of coarse scatter profiles for a set of CBCT data in either image domain or projection domain. A denoising algorithm designed specifically for Poisson signals is then applied to derive the final scatter distribution. Qualitative and quantitative evaluations using thorax and abdomen phantoms with Monte Carlo (MC) simulations, experimental Catphan phantom data, and in vivo human data acquired for a clinical image guided radiation therapy were performed. Scatter correction in both projection domain and image domain was conducted and the influences of segmentation method, mismatched attenuation coefficients, and spectrum model as well as parameter selection were also investigated. Results: Results show that the proposed algorithm can significantly reduce scatter artifacts and recover the correct HU in either projection domain or image domain. For the MC thorax phantom study, four-components segmentation yields the best results, while the results of three-components segmentation are still acceptable. The parameters (iteration number K and weight β) affect the accuracy of the scatter correction and the results get improved as K and β increase. It was found that variations in attenuation coefficient accuracies only slightly impact the performance of the proposed processing. For the Catphan phantom data, the mean value over all pixels in the residual image is reduced from −21.8 to −0.2 HU and 0.7 HU for projection

  6. Coupling SLEUTH model and population projection to simulate urban growth of the Baltimore-Washington metropolitan area

    Science.gov (United States)

    Shao, Y.; Zhao, S.

    2015-12-01

    This study used two modelling approaches to predict future urban landscapes for the Baltimore-Washington metropolitan area. In the first approach, we implemented traditional SLEUTH urban simulation model by using publicly available and locally-developed land cover and transportation data. Historical land cover data from 1992, 2001, 2006, and 2011 were used to calibrate the SLEUTH model and predict urban growth from 2011 to 2070. The SLEUTH model achieved 94.8% overall accuracy for validation year 2014. For the second modelling approach, we used a future population projection for 2050, aided by a strong population-imperviousness statistical relationship (R2 ~ 0.95), to predict impervious surface density for each county. These population-predicted impervious surface density values were compared to SLEUTH model output, at the county spatial scale. R2 of 0.84 suggested general agreement of overall pattern, although SLEUTH generated higher impervious surface density values for 36 out of 40 counties. For population-predicted impervious surface density, we further developed a lookup table approach to integrate SLEUTH output and generated a spatially explicit urban map for 2050. This lookup table approach has high potential to integrate population-predicted and SLEUTH-predicted urban landscape, especially when future population can be predicted with reasonable accuracy.

  7. Impacts of climate change on peanut yield in China simulated by CMIP5 multi-model ensemble projections

    Science.gov (United States)

    Xu, Hanqing; Tian, Zhan; Zhong, Honglin; Fan, Dongli; Shi, Runhe; Niu, Yilong; He, Xiaogang; Chen, Maosi

    2017-09-01

    Peanut is one of the major edible vegetable oil crops in China, whose growth and yield are very sensitive to climate change. In addition, agriculture climate resources are expected to be redistributed under climate change, which will further influence the growth, development, cropping patterns, distribution and production of peanut. In this study, we used the DSSAT-Peanut model to examine the climate change impacts on peanut production, oil industry and oil food security in China. This model is first calibrated using site observations including 31 years' (1981-2011) climate, soil and agronomy data. This calibrated model is then employed to simulate the future peanut yield based on 20 climate scenarios from 5 Global Circulation Models (GCMs) developed by the InterSectoral Impact Model Intercomparison Project (ISIMIP) driven by 4 Representative Concentration Pathways (RCPs). Results indicate that the irrigated peanut yield will decrease 2.6% under the RCP 2.6 scenario, 9.9% under the RCP 4.5 scenario and 29% under the RCP 8.5 scenario, respectively. Similarly, the rain-fed peanut yield will also decrease, with a 2.5% reduction under the RCP 2.6 scenario, 11.5% reduction under the RCP 4.5 scenario and 30% reduction under the RCP 8.5 scenario, respectively.

  8. Tantalum cones and bone defects in revision total knee arthroplasty.

    Science.gov (United States)

    Boureau, F; Putman, S; Arnould, A; Dereudre, G; Migaud, H; Pasquier, G

    2015-04-01

    Management of bone loss is a major challenge in revision total knee arthroplasty (TKA). The development of preformed porous tantalum cones offers new possibilities, because they seem to have biological and mechanical qualities that facilitate osseointegration. Compared to the original procedure, when metaphyseal bone defects are too severe, a single tantalum cone may not be enough and we have developed a technique that could extend the indications for this cone in these cases. We used 2 cones to fill femoral bone defects in 7 patients. There were no complications due to wear of the tantalum cones. Radiological follow-up did show any migration or loosening. The short-term results confirm the interest of porous tantalum cones and suggest that they can be an alternative to allografts or megaprostheses in case of massive bone defects. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  9. Techniques for optimizing nanotips derived from frozen taylor cones

    Science.gov (United States)

    Hirsch, Gregory

    2017-12-05

    Optimization techniques are disclosed for producing sharp and stable tips/nanotips relying on liquid Taylor cones created from electrically conductive materials with high melting points. A wire substrate of such a material with a preform end in the shape of a regular or concave cone, is first melted with a focused laser beam. Under the influence of a high positive potential, a Taylor cone in a liquid/molten state is formed at that end. The cone is then quenched upon cessation of the laser power, thus freezing the Taylor cone. The tip of the frozen Taylor cone is reheated by the laser to allow its precise localized melting and shaping. Tips thus obtained yield desirable end-forms suitable as electron field emission sources for a variety of applications. In-situ regeneration of the tip is readily accomplished. These tips can also be employed as regenerable bright ion sources using field ionization/desorption of introduced chemical species.

  10. High-fidelity artifact correction for cone-beam CT imaging of the brain

    Science.gov (United States)

    Sisniega, A.; Zbijewski, W.; Xu, J.; Dang, H.; Stayman, J. W.; Yorkston, J.; Aygun, N.; Koliatsos, V.; Siewerdsen, J. H.

    2015-02-01

    CT is the frontline imaging modality for diagnosis of acute traumatic brain injury (TBI), involving the detection of fresh blood in the brain (contrast of 30-50 HU, detail size down to 1 mm) in a non-contrast-enhanced exam. A dedicated point-of-care imaging system based on cone-beam CT (CBCT) could benefit early detection of TBI and improve direction to appropriate therapy. However, flat-panel detector (FPD) CBCT is challenged by artifacts that degrade contrast resolution and limit application in soft-tissue imaging. We present and evaluate a fairly comprehensive framework for artifact correction to enable soft-tissue brain imaging with FPD CBCT. The framework includes a fast Monte Carlo (MC)-based scatter estimation method complemented by corrections for detector lag, veiling glare, and beam hardening. The fast MC scatter estimation combines GPU acceleration, variance reduction, and simulation with a low number of photon histories and reduced number of projection angles (sparse MC) augmented by kernel de-noising to yield a runtime of ~4 min per scan. Scatter correction is combined with two-pass beam hardening correction. Detector lag correction is based on temporal deconvolution of the measured lag response function. The effects of detector veiling glare are reduced by deconvolution of the glare response function representing the long range tails of the detector point-spread function. The performance of the correction framework is quantified in experiments using a realistic head phantom on a testbench for FPD CBCT. Uncorrected reconstructions were non-diagnostic for soft-tissue imaging tasks in the brain. After processing with the artifact correction framework, image uniformity was substantially improved, and artifacts were reduced to a level that enabled visualization of ~3 mm simulated bleeds throughout the brain. Non-uniformity (cupping) was reduced by a factor of 5, and contrast of simulated bleeds was improved from ~7 to 49.7 HU, in good agreement

  11. The Shape of Color: Retinal Cones and Spectral Dispersion

    OpenAIRE

    Medeiros, John A.; Medeiros, Nancy E.

    2014-01-01

    Why are the retinal color receptors cone-shaped? This is not a trivial question: the cone shape is evidently a universal feature of the color receptors while the achromatic rod receptors are always rod-shaped. What might be behind this dichotomy has not previously been explored in any meaningful way. We suggest here that the cone shape is not an incidental feature, but actually integral to cone function. We describe a waveguide mode cut-off effect that can physically separate light into its s...

  12. High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Anas, Emran Mohammad Abu; Hasan, Md Kamrul [Department of Electrical and Electronic Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000 (Bangladesh); Kim, Jae Gon; Lee, Soo Yeol, E-mail: khasan@eee.buet.ac.b [Department of Biomedical Engineering, Kyung Hee University, Kyungki 446-701 (Korea, Republic of)

    2011-10-07

    The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

  13. Cone visual pigments of aquatic mammals.

    Science.gov (United States)

    Newman, Lucy A; Robinson, Phyllis R

    2005-01-01

    It has long been hypothesized that the visual systems of animals are evolutionarily adapted to their visual environment. The entrance many millions of years ago of mammals into the sea gave these new aquatic mammals completely novel visual surroundings with respect to light availability and predominant wavelengths. This study examines the cone opsins of marine mammals, hypothesizing, based on previous studies [Fasick et al. (1998) and Levenson & Dizon (2003)], that the deep-dwelling marine mammals would not have color vision because the pressure to maintain color vision in the dark monochromatic ocean environment has been relaxed. Short-wavelength-sensitive (SWS) and long-wavelength-sensitive (LWS) cone opsin genes from two orders (Cetacea and Sirenia) and an additional suborder (Pinnipedia) of aquatic mammals were amplified from genomic DNA (for SWS) and cDNA (for LWS) by PCR, cloned, and sequenced. All animals studied from the order Cetacea have SWS pseudogenes, whereas a representative from the order Sirenia has an intact SWS gene, for which the corresponding mRNA was found in the retina. One of the pinnipeds studied (harp seal) has an SWS pseudogene, while another species (harbor seal) appeared to have an intact SWS gene. However, no SWS cone opsin mRNA was found in the harbor seal retina, suggesting a promoter or splice site mutation preventing transcription of the gene. The LWS opsins from the different species were expressed in mammalian cells and reconstituted with the 11-cis-retinal chromophore in order to determine maximal absorption wavelengths (lambda(max)) for each. The deeper dwelling Cetacean species had blue shifted lambda(max) values compared to shallower-dwelling aquatic species. Taken together, these findings support the hypothesis that in the monochromatic oceanic habitat, the pressure to maintain color vision has been relaxed and mutations are retained in the SWS genes, resulting in pseudogenes. Additionally, LWS opsins are retained in the

  14. Enhancing k-space quantitative susceptibility mapping by enforcing consistency on the cone data (CCD) with structural priors.

    Science.gov (United States)

    Wen, Yan; Wang, Yi; Liu, Tian

    2016-02-01

    The inversion from the magnetic field to the magnetic susceptibility distribution is ill-posed because the dipole kernel, which relates the magnetic susceptibility to the magnetic field, has zeroes at a pair of cone surfaces in the k-space, leading to streaking artifacts on the reconstructed quantitative susceptibility maps (QSM). A method to impose consistency on the cone data (CCD) with structural priors is proposed to improve the solutions of k-space methods. The information in the cone region is recovered by enforcing structural consistency with structural prior, while information in the noncone trust region is enforced to be consistent with the magnetic field measurements in k-space. This CCD method was evaluated by comparing the initial results of existing QSM algorithms to the QSM results after CCD enhancement with respect to the COSMOS results in simulation, phantom, and in vivo human brain. The proposed method demonstrated suppression of streaking artifacts and the resulting QSM showed better agreement with reference standard QSM compared with other k-space based methods. By enforcing consistency with structural priors in the cone region, the missing data in the cone can be recovered and the streaking artifacts in QSM can be suppressed. © 2015 Wiley Periodicals, Inc.

  15. Field studies of beach cones as coastal erosion control/reversal devices for areas with significant oil and gas activities. Final report, February 24, 1992--September 18, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Law, V.J.

    1995-09-18

    The primary objective of this project was to evaluate the utility of a device called the {open_quotes}beach cone{close_quotes} in combating coastal erosion. Seven initial sites were selected for testing beach cones in a variety of geometric configurations. Permits were obtained from the State of Louisiana and the U.S. Army Corps of Engineers to perform the work associated with this study. Six hundred beach cones were actually installed at six of the sites in late July and early August, 1992. Findings indicate that beach cones accreted significant amounts of materials along the beach of a barrier island, and they might have been instrumental in repairing an approximately 200 meter gap in the island. At the eighth installation the amount of accreted material was measured by surveys to be 2200 cubic meters (2900 cubic yards) in February of 1993, when the cones were found to have been completely covered by the material. At other test sites, accretion rates have been less dramatic but importantly, no significant additional erosion has occurred, which is a positive result. The cost of sediment accretion using beach cones was found to be about $13.72 per cubic yard, which would be much lower if the cones were mass produced (on the order of $3.00 per cubic yard). The survival of the cones through the fringes of Hurricane Andrew indicates that they can be anchored sufficiently to survive significant storms. The measurements of the cones settling rates indicate that this effect is not significant enough to hinder their effectiveness. A subcontract to Xavier University to assess the ecological quality of the experimental sites involved the study of the biogeochemical cycle of trace metals. The highest concentration of heavy metals were near a fishing camp while the lowest levels were in the beach sand of a barrier island. This suggests that the metals do not occur naturally in these areas, but have been placed in the sediments by man`s activities.

  16. Emission of energetic protons from relativistic intensity laser interaction with a cone-wire target.

    Science.gov (United States)

    Paradkar, B S; Yabuuchi, T; Sawada, H; Higginson, D P; Link, A; Wei, M S; Stephens, R B; Krasheninnikov, S I; Beg, F N

    2012-11-01

    Emission of energetic protons (maximum energy ∼18 MeV) from the interaction of relativistic intensity laser with a cone-wire target is experimentally measured and numerically simulated with hybrid particle-in-cell code, lsp [D. R. Welch et al., Phys. Plasmas 13, 063105 (2006)]. The protons originate from the wire attached to the cone after the OMEGA EP laser (670 J, 10 ps, 5 × 10^{18} W/cm^{2}) deposits its energy inside the cone. These protons are accelerated from the contaminant layer on the wire surface, and are measured in the radial direction, i.e., in a direction transverse to the wire length. Simulations show that the radial electric field, responsible for the proton acceleration, is excited by three factors, viz., (i) transverse momentum of the relativistic fast electrons beam entering into the wire, (ii) scattering of electrons inside the wire, and (iii) refluxing of escaped electrons by "fountain effect" at the end of the wire. The underlying physics of radial electric field and acceleration of protons is discussed.

  17. A Cone Jet-Finding Algorithm for Heavy-Ion Collisions at LHCEnergies

    Energy Technology Data Exchange (ETDEWEB)

    Blyth, S.-L.; Horner, M.J.; Awes, T.C.; Cormier, T.; Gray, H.M.; Klay, J.L.; Klein, S.R.; van Leeuwen, M.; Morsch, A.; Odyniec, G.; Pavlinov, A.

    2006-07-27

    Standard jet finding techniques used in elementary particle collisions have not been successful in the high track density of heavy-ion collisions. This paper describes a modified cone-type jet finding algorithm developed for the complex environment of heavy-ion collisions. The primary modification to the algorithm is the evaluation and subtraction of the large background energy, arising from uncorrelated soft hadrons, in each collision. A detailed analysis of the background energy and its event-by-event fluctuations has been performed on simulated data, and a method developed to estimate the background energy inside the jet cone from the measured energy outside the cone on an event-by-event basis. The algorithm has been tested using Monte-Carlo simulations of Pb+Pb collisions at {radical}s = 5.5 TeV for the ALICE detector at the LHC. The algorithm can reconstruct jets with a transverse energy of 50 GeV and above with an energy resolution of {approx} 30%.

  18. Flow Lines Under Perturbation within Section Cones

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    map from the closed unit interval with the natural partial order inherited from the order of the real numbers to the manifold with the partial order defined as above, which furthermore preserves the partial orders. We examine di-paths between two critical points of minimal and of maximal index up......We want to examine a closed smooth manifold together with a certain partial order: In the set of vector fields on , , we define a section cone - a convex subset of characterized by the property that if is a singular point for some vector field in then this is the case for all members of . We say...

  19. Korean mean and extreme sea levels projection under AR5 climate change scenarios using Monte-Carlo simulations

    Science.gov (United States)

    Cha, W. Y.; Choi, J.; Okjeong, L.; Park, Y.; Lee, J.; Kim, S.

    2016-12-01

    Coastal areas are vulnerable to sea level rise. However, the preparation capability for sea level rise of South Korea is insufficient. Global sea level rise due to climate change is causing a lot of damage to the coastal zone. In addition, since the coastal population in South Korea shows a growing trend, many coastal cities are likely to become more vulnerable to sea level rise. The impacts of future sea level rise will affect shoreline erosion, the disappearance of coastal wetlands, the intrusion of sea water, and increased flood vulnerability due to the performance reduction of the hydraulic structures. The purpose of this study is to estimate the increase amount of the Korea sea level rise under AR5 climate change scenarios. The study area is Busan, Incheon, Mokpo, and Sokcho, which are coastal cities representing South Korea. In order to consider the global and local components for future sea level rise at the same time, the accelerating rates of sea level rise for each city are first calculated using the global rate of sea level rise presented in the IPCC Fifth Assessment Report. After that, the local sea level rise trend derived from observations of each city is additionally considered, and the final future sea level rise is projected. In addition, uncertainties included in the acceleration rate from the global sea level rise and localized upward trend derived from local observations are reflected in probabilistic projection of the future sea level rise range. In a similar way, the extreme sea level rise is also estimated. Simulation results show that extreme sea levels in 2100 could rise by more than 1 meter. It is also expected to increase the rate of sea level rise gradually with increasing greenhouse gas concentrations. The results of this study will be utilized for flood vulnerability assessment in coastal areas of South Korea later. AcknowledgementThis research was supported by a grant `Development of the Evaluation Technology for Complex Causes of

  20. Estimating the impact of enterprise resource planning project management decisions on post-implementation maintenance costs: a case study using simulation modelling

    Science.gov (United States)

    Fryling, Meg

    2010-11-01

    Organisations often make implementation decisions with little consideration for the maintenance phase of an enterprise resource planning (ERP) system, resulting in significant recurring maintenance costs. Poor cost estimations are likely related to the lack of an appropriate framework for enterprise-wide pre-packaged software maintenance, which requires an ongoing relationship with the software vendor (Markus, M.L., Tanis, C., and Fenema, P.C., 2000. Multisite ERP implementation. CACM, 43 (4), 42-46). The end result is that critical project decisions are made with little empirical data, resulting in substantial long-term cost impacts. The product of this research is a formal dynamic simulation model that enables theory testing, scenario exploration and policy analysis. The simulation model ERPMAINT1 was developed by combining and extending existing frameworks in several research domains, and by incorporating quantitative and qualitative case study data. The ERPMAINT1 model evaluates tradeoffs between different ERP project management decisions and their impact on post-implementation total cost of ownership (TCO). Through model simulations a variety of dynamic insights were revealed that could assist ERP project managers. Major findings from the simulation show that upfront investments in mentoring and system exposure translate to long-term cost savings. The findings also indicate that in addition to customisations, add-ons have a significant impact on TCO.