Optical and mechanical design of the extended x-ray absorption fine structure (EXAFS) beam-line at Indus-II synchrotron source

International Nuclear Information System (INIS)

Das, N.C.; Jha, S.N.; Bhattacharyya, D.; Sinha, A.K.; Mishra, V.K.; Verma, Vishnu; Ghosh, A.K.

2002-11-01

An extended x-ray absorption fine structure (EXAFS) beam line for x-ray absorption studies using energy dispersive geometry and position sensitive detector is being designed for the INDUS-II Synchrotron source. The beam line would be used for doing x-ray absorption experiments involving measurements of fme structures above the absorption edge of different species of atoms in a material The results of the above experiments would lead to the determination of different important structural parameters of materials viz.. inter-atomic distance. co-ordination number, degree of disorder and radial distribution function etc. The optical design of the beam line has been completed based on the working principle that a single crystal bent in the shape of an ellipse by a crystal bender would act as a dispersing as well as focusing element. The mechanical design of the beam line including the crystal bender has also been completed and discussed here. Calculations have been done to detennine the temperature profile on the different components of the beam line under exposure to synchrotron radiation and proper cooling channels have been designed to bring down the heat load on the components. (author)

Numerical Simulation of Dispersion from Urban Greenhouse Gas Sources

Science.gov (United States)

Nottrott, Anders; Tan, Sze; He, Yonggang; Winkler, Renato

2017-04-01

Cities are characterized by complex topography, inhomogeneous turbulence, and variable pollutant source distributions. These features create a scale separation between local sources and urban scale emissions estimates known as the Grey-Zone. Modern computational fluid dynamics (CFD) techniques provide a quasi-deterministic, physically based toolset to bridge the scale separation gap between source level dynamics, local measurements, and urban scale emissions inventories. CFD has the capability to represent complex building topography and capture detailed 3D turbulence fields in the urban boundary layer. This presentation discusses the application of OpenFOAM to urban CFD simulations of natural gas leaks in cities. OpenFOAM is an open source software for advanced numerical simulation of engineering and environmental fluid flows. When combined with free or low cost computer aided drawing and GIS, OpenFOAM generates a detailed, 3D representation of urban wind fields. OpenFOAM was applied to model scalar emissions from various components of the natural gas distribution system, to study the impact of urban meteorology on mobile greenhouse gas measurements. The numerical experiments demonstrate that CH4 concentration profiles are highly sensitive to the relative location of emission sources and buildings. Sources separated by distances of 5-10 meters showed significant differences in vertical dispersion of plumes, due to building wake effects. The OpenFOAM flow fields were combined with an inverse, stochastic dispersion model to quantify and visualize the sensitivity of point sensors to upwind sources in various built environments. The Boussinesq approximation was applied to investigate the effects of canopy layer temperature gradients and convection on sensor footprints.

Contaminant dispersion prediction and source estimation with integrated Gaussian-machine learning network model for point source emission in atmosphere

International Nuclear Information System (INIS)

Ma, Denglong; Zhang, Zaoxiao

2016-01-01

Highlights: • The intelligent network models were built to predict contaminant gas concentrations. • The improved network models coupled with Gaussian dispersion model were presented. • New model has high efficiency and accuracy for concentration prediction. • New model were applied to indentify the leakage source with satisfied results. - Abstract: Gas dispersion model is important for predicting the gas concentrations when contaminant gas leakage occurs. Intelligent network models such as radial basis function (RBF), back propagation (BP) neural network and support vector machine (SVM) model can be used for gas dispersion prediction. However, the prediction results from these network models with too many inputs based on original monitoring parameters are not in good agreement with the experimental data. Then, a new series of machine learning algorithms (MLA) models combined classic Gaussian model with MLA algorithm has been presented. The prediction results from new models are improved greatly. Among these models, Gaussian-SVM model performs best and its computation time is close to that of classic Gaussian dispersion model. Finally, Gaussian-MLA models were applied to identifying the emission source parameters with the particle swarm optimization (PSO) method. The estimation performance of PSO with Gaussian-MLA is better than that with Gaussian, Lagrangian stochastic (LS) dispersion model and network models based on original monitoring parameters. Hence, the new prediction model based on Gaussian-MLA is potentially a good method to predict contaminant gas dispersion as well as a good forward model in emission source parameters identification problem.

Contaminant dispersion prediction and source estimation with integrated Gaussian-machine learning network model for point source emission in atmosphere

Energy Technology Data Exchange (ETDEWEB)

Ma, Denglong [Fuli School of Food Equipment Engineering and Science, Xi’an Jiaotong University, No.28 Xianning West Road, Xi’an 710049 (China); Zhang, Zaoxiao, E-mail: zhangzx@mail.xjtu.edu.cn [State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, No.28 Xianning West Road, Xi’an 710049 (China); School of Chemical Engineering and Technology, Xi’an Jiaotong University, No.28 Xianning West Road, Xi’an 710049 (China)

2016-07-05

Highlights: • The intelligent network models were built to predict contaminant gas concentrations. • The improved network models coupled with Gaussian dispersion model were presented. • New model has high efficiency and accuracy for concentration prediction. • New model were applied to indentify the leakage source with satisfied results. - Abstract: Gas dispersion model is important for predicting the gas concentrations when contaminant gas leakage occurs. Intelligent network models such as radial basis function (RBF), back propagation (BP) neural network and support vector machine (SVM) model can be used for gas dispersion prediction. However, the prediction results from these network models with too many inputs based on original monitoring parameters are not in good agreement with the experimental data. Then, a new series of machine learning algorithms (MLA) models combined classic Gaussian model with MLA algorithm has been presented. The prediction results from new models are improved greatly. Among these models, Gaussian-SVM model performs best and its computation time is close to that of classic Gaussian dispersion model. Finally, Gaussian-MLA models were applied to identifying the emission source parameters with the particle swarm optimization (PSO) method. The estimation performance of PSO with Gaussian-MLA is better than that with Gaussian, Lagrangian stochastic (LS) dispersion model and network models based on original monitoring parameters. Hence, the new prediction model based on Gaussian-MLA is potentially a good method to predict contaminant gas dispersion as well as a good forward model in emission source parameters identification problem.

Non-uniform dispersion of the source-sink relationship alters wavefront curvature.

Directory of Open Access Journals (Sweden)

Lucia Romero

Full Text Available The distribution of cellular source-sink relationships plays an important role in cardiac propagation. It can lead to conduction slowing and block as well as wave fractionation. It is of great interest to unravel the mechanisms underlying evolution in wavefront geometry. Our goal is to investigate the role of the source-sink relationship on wavefront geometry using computer simulations. We analyzed the role of variability in the microscopic source-sink relationship in driving changes in wavefront geometry. The electrophysiological activity of a homogeneous isotropic tissue was simulated using the ten Tusscher and Panfilov 2006 action potential model and the source-sink relationship was characterized using an improved version of the Romero et al. safety factor formulation (SFm2. Our simulations reveal that non-uniform dispersion of the cellular source-sink relationship (dispersion along the wavefront leads to alterations in curvature. To better understand the role of the source-sink relationship in the process of wave formation, the electrophysiological activity at the initiation of excitation waves in a 1D strand was examined and the source-sink relationship was characterized using the two recently updated safety factor formulations: the SFm2 and the Boyle-Vigmond (SFVB definitions. The electrophysiological activity at the initiation of excitation waves was intimately related to the SFm2 profiles, while the SFVB led to several counterintuitive observations. Importantly, with the SFm2 characterization, a critical source-sink relationship for initiation of excitation waves was identified, which was independent of the size of the electrode of excitation, membrane excitability, or tissue conductivity. In conclusion, our work suggests that non-uniform dispersion of the source-sink relationship alters wavefront curvature and a critical source-sink relationship profile separates wave expansion from collapse. Our study reinforces the idea that the

Subcarrier multiplexing tolerant dispersion transmission system employing optical broadband sources.

Science.gov (United States)

Grassi, Fulvio; Mora, José; Ortega, Beatriz; Capmany, José

2009-03-16

This paper presents a novel SCM optical transmission system for next-generation WDM-PONs combining broadband optical sources and a Mach-Zehnder interferometric structure. The approach leeds to transport RF signals up to 50 GHz being compatible with RoF systems since a second configuration has been proposed in order to overcome dispersion carrier suppression effect using DSB modulation. The theoretical analysis validates the potentiality of the system also considering the effects of the dispersion slope over the transmission window. (c) 2009 Optical Society of America

The description of compton lines in energy-dispersive x-ray Fluorescence

International Nuclear Information System (INIS)

Van Gysel, Mon; Van Espen, P.J.M.

2001-01-01

Energy-Dispersive X-Ray Fluorescence (ED-XRF) is a non-destructive technique for the element analysis in a concentration range ppm - % making use of X rays up to 100 keV. Generally, two photon matter interactions occur, respectively absorption and scattering. The absorption of incident photons gives raise to characteristic lines. Scattering gives an incoherent and a coherent line. A Gaussian peak model is adequate to describe the characteristic and coherent scattered lines. Incoherent lines appear as non-Gaussian, broadened peaks. The profile of a Compton peak is complex. It depends on the geometry and the composition of the sample. Especially, when analyzing a low Z matrix; dominant scattering and multiple scattering may cause large interferences. The absence of an appropriate fitting model makes the Compton profile seen as a limiting factor in the evaluation of spectra. An accurate description of incoherent lines should improve quantitative analysis. Therefore, a suitable fitting model, making use of the expertise of non-linear least squares procedures and Monte-Carlo calculations was systematically investigated. The proposed model, containing a modified Gaussian, is tested on experimental data recorded with a HPGe detector

Study of abrasive wear process of lining of grinding chamber of vortex-acoustic disperser

Science.gov (United States)

Perelygin, D. N.

2018-03-01

The theoretical and experimental studies of the process of gas-abrasive wear of the lining of a vortex-acoustic disperser made it possible to establish the conditions and patterns of their occurrence and also to develop proposals for its reduction.

Sensitivity of numerical dispersion modeling to explosive source parameters

International Nuclear Information System (INIS)

Baskett, R.L.; Cederwall, R.T.

1991-01-01

The calculation of downwind concentrations from non-traditional sources, such as explosions, provides unique challenges to dispersion models. The US Department of Energy has assigned the Atmospheric Release Advisory Capability (ARAC) at the Lawrence Livermore National Laboratory (LLNL) the task of estimating the impact of accidental radiological releases to the atmosphere anywhere in the world. Our experience includes responses to over 25 incidents in the past 16 years, and about 150 exercises a year. Examples of responses to explosive accidents include the 1980 Titan 2 missile fuel explosion near Damascus, Arkansas and the hydrogen gas explosion in the 1986 Chernobyl nuclear power plant accident. Based on judgment and experience, we frequently estimate the source geometry and the amount of toxic material aerosolized as well as its particle size distribution. To expedite our real-time response, we developed some automated algorithms and default assumptions about several potential sources. It is useful to know how well these algorithms perform against real-world measurements and how sensitive our dispersion model is to the potential range of input values. In this paper we present the algorithms we use to simulate explosive events, compare these methods with limited field data measurements, and analyze their sensitivity to input parameters. 14 refs., 7 figs., 2 tabs

GARLIC, a shielding program for GAmma Radiation from Line- and Cylinder-sources

Energy Technology Data Exchange (ETDEWEB)

Roos, Matts

1959-07-15

GARLIC is a program for computing the gamma ray flux or dose rate at a shielded idotropic point detector, due to a line source or the line equivalent of a cylindrical source. The source strength distribution along the line must be either uniform or an arbitrary part of the positive half-cycle of a cosine function. The line source can be oriented arbitrarily with respect to the main shield and the detector, except that the detector must not be located on the line source or on its extension. The main source is a homogeneous plane slab in which scattered radiation is accounted for by multiplying each point element of the line source by a point source build-up factor inside the integral over the point elements. Between, the main shield and the line source additional shields can be introduced, which are either plane slabs, parallel to the main shield, or cylindrical rings, coaxial with the line source. Scattered radiation in the additional shields can only be accounted for by constant build-up factors outside the integral. GARLIC-xyz is an extended version particularly suited for the frequently met problem of shielding a room containing a large number of line sources in different positions. The program computes the angles and linear dimensions of a problem for GARLIC when the positions of the detector point and the end points of the line source are given as points in an arbitrary rectangular coordinate system. As an example the isodose curves in water are presented for a monoenergetic cosine-distributed line source at several source energies and for an operating fuel element of the Swedish reactor R3.

Dependency of non-homogeneity energy dispersion on absorbance line-shape of luminescent polymers

Energy Technology Data Exchange (ETDEWEB)

Silva, Marcelo Castanheira da, E-mail: mar_castanheira@yahoo.com.br [Centro de Ciências Biológicas e da Natureza, Universidade Federal do Acre, CP 500, 69915-900 Rio Branco, AC (Brazil); Instituto de Física, Universidade Federal de Uberlândia, CP 593, 38400-902 Uberlândia, MG (Brazil); Santos Silva, H.; Silva, R.A.; Marletta, Alexandre [Instituto de Física, Universidade Federal de Uberlândia, CP 593, 38400-902 Uberlândia, MG (Brazil)

2013-01-16

In this paper, we study the importance of the non-homogeneity energy dispersion on absorption line-shape of luminescent polymers. The optical transition probability was calculated based on the molecular exciton model, Franck–Condon states, Gaussian distribution of non-entangled chains with conjugate degree n, semi-empirical parameterization of energy gap, electric dipole moment, and electron-vibrational mode coupling. Based on the approach of the energy gap functional dependence 1/n, the inclusion of the non-homogeneity energy dispersion 1/n{sup 2} is essential to obtain good experimental data agreement, mainly, where the absorption spectra display peaks width of about 65 meV. For unresolved absorption spectra, such as those observed for a large number of conjugated polymers processed via spin-coating technique, for example, the non-homogeneity energy dispersion parameterization is not significant. Results were supported by the application of the model for poly (p-phenylene vinylene) films.

Artificial induction of third-stage dispersal juveniles of Bursaphelenchus xylophilus using newly established inbred lines.

Directory of Open Access Journals (Sweden)

Suguru E Tanaka

Full Text Available The pine wood nematode, Bursaphelenchus xylophilus, is the causal agent of pine wilt disease. This nematode has two developmental forms in its life cycle; i.e., the propagative and dispersal forms. The former is the form that builds up its population inside the host pine. The latter is specialized for transport by the vector. This form is separated into two dispersal stages (third and fourth; the third-stage dispersal juvenile (JIII is specialized for survival under unfavorable conditions, whereas the fourth-stage juvenile (JIV, which is induced by a chemical signal from the carrier Monochamus beetle, is transported to new host pines and invades them. Because of its importance in the disease cycle, molecular and chemical aspects of the JIV have been investigated, while the mechanism of JIII induction has not been sufficiently investigated. In an effort to clarify the JIII induction process, we established inbred lines of B. xylophilus and compared their biological features. We found that the total number of nematodes (propagation proportion was negatively correlated with the JIII emergence proportion, likely because nematode development was arrested at JIII; i.e., they could not develop to adults via the reproductive stage. In addition, JIII induction seemed to be regulated by a small number of genes because the JIII induction proportion varied among inbred lines despite the high homozygosity of the parental line. We also demonstrated that JIII can be artificially induced by the nematode's secreted substances. This is the first report of artificial induction of JIII in B. xylophilus. The dauer (dispersal juvenile of the model organism Caenorhabditis elegans corresponds functionally to JIII of B. xylophilus, and this stage is known to be induced by a chemical signal referred to as daumone, derived from the nematodes' secretion. The artificial induction of JIII suggests the presence of daumone-like material in B. xylophilus.

Presentation of Austrians recommended dispersion model for tunnel portals

Energy Technology Data Exchange (ETDEWEB)

Oettl, D.; Sturm, P.; Almbauer, R. [Inst. for Internal Combustion Engines and Thermodynamics, Graz Univ. of Technology (Austria)

2004-07-01

Street tunnels in cities are often suggested as solution to avoid daily congestions but also to prevent residential areas from high noise and air pollution emissions. In case of longitudinal ventilated tunnels high pollution levels may occur in the vicinity of the portals. The dispersion of pollutants from tunnel portals is considered to differ significantly from those of other sources, such as line or point sources. To the best of the authors knowledge, there exist currently two distinct dispersion models, which are especially designed to treat dispersion from tunnel portals. Okamoto et al proposed a diagnostic wind field model, where the dispersion is modelled using a Taylor-Galerkin-Forester filter method. Oettl et al. developed a Lagrangian-type model (GRAL TM 3.5=Graz Lagrangian model Tunnel Module version 3.5), which is briefly described in the next section. (orig.)

Seed source, seed traits, and frugivore habits: Implications for dispersal quality of two sympatric primates.

Science.gov (United States)

Benítez-Malvido, Julieta; González-Di Pierro, Ana Ma; Lombera, Rafael; Guillén, Susana; Estrada, Alejandro

2014-06-01

• Premise of the study: Frugivore selection of fruits and treatment of seeds together with seed deposition site are crucial for the population dynamics of vertebrate-dispersed plants. However, frugivore species may influence dispersal quality differently even when feeding on the same fruit species and, while animals disperse some seeds, others simply fall beneath the parent plant.• Methods: In southern Mexico, we investigated to see if within-species seed traits (i.e., length, width, weight, and volume) and germination success differed according to seed source. For five tropical tree species we obtained ingested seeds from two sources, howler monkey (Alouatta pigra) and spider monkey (Ateles geoffroyi) feces; and noningested seeds from two sources, the ground and tree crowns (with predispersed seeds used as control).• Key results: A principal components' analysis showed that traits of seeds ingested by howler monkeys differed from other sources while seeds ingested by spider monkeys were similar to noningested seeds. Howlers consumed on average the larger seeds in Ampelocera hottlei, Brosimum lactescens, and Dialium guianense. Both primate species consumed the smaller seeds in Spondias mombin, while no seed trait differences among seed sources were found in Spondias radlkoferi. For all five tree species, germination rate was greatest for seeds ingested by howler monkeys.• Conclusions: For the studied plant species, seed ingestion by howler monkeys confers higher dispersal quality than ingestion by spider monkeys or nondispersal. Dispersal services of both primate species, however, are not redundant and may contribute to germination heterogeneity within plant populations in tropical forests. © 2014 Botanical Society of America, Inc.

Effects of elevated line sources on turbulent mixing in channel flow

Science.gov (United States)

Nguyen, Quoc; Papavassiliou, Dimitrios

2016-11-01

Fluids mixing in turbulent flows has been studied extensively, due to the importance of this phenomena in nature and engineering. Convection effects along with motion of three-dimensional coherent structures in turbulent flow disperse a substance more efficiently than molecular diffusion does on its own. We present here, however, a study that explores the conditions under which turbulent mixing does not happen, when different substances are released into the flow field from different vertical locations. The study uses a method which combines Direct Numerical Simulation (DNS) with Lagrangian Scalar Tracking (LST) to simulate a turbulent channel flow and track the motion of passive scalars with different Schmidt numbers (Sc). The particles are released from several instantaneous line sources, ranging from the wall to the center region of the channel. The combined effects of mean velocity difference, molecular diffusion and near-wall coherent structures lead to the observation of different concentrations of particles downstream from the source. We then explore in details the conditions under which particles mixing would not happen. Results from numerical simulation at friction Reynolds number of 300 and 600 will be discussed and for Sc ranging from 0.1 to 2,400.

Chernobyl source term, atmospheric dispersion, and dose estimation

International Nuclear Information System (INIS)

Gudiksen, P.H.; Harvey, T.F.; Lange, R.

1988-02-01

The Chernobyl source term available for long-range transport was estimated by integration of radiological measurements with atmospheric dispersion modeling, and by reactor core radionuclide inventory estimation in conjunction with WASH-1400 release fractions associated with specific chemical groups. These analyses indicated that essentially all of the noble gases, 80% of the radioiodines, 40% of the radiocesium, 10% of the tellurium, and about 1% or less of the more refractory elements were released. Atmospheric dispersion modeling of the radioactive cloud over the Northern Hemisphere revealed that the cloud became segmented during the first day, with the lower section heading toward Scandinavia and the uppper part heading in a southeasterly direction with subsequent transport across Asia to Japan, the North Pacific, and the west coast of North America. The inhalation doses due to direct cloud exposure were estimated to exceed 10 mGy near the Chernobyl area, to range between 0.1 and 0.001 mGy within most of Europe, and to be generally less than 0.00001 mGy within the US. The Chernobyl source term was several orders of magnitude greater than those associated with the Windscale and TMI reactor accidents, while the 137 Cs from the Chernobyl event is about 6% of that released by the US and USSR atmospheric nuclear weapon tests. 9 refs., 3 figs., 6 tabs

A directly heated electron beam line source

International Nuclear Information System (INIS)

Iqbal, M.; Masood, K.; Rafiq, M.; Chaudhry, M.A.

2002-05-01

A 140-mm cathode length, Electron Beam Line Source with a high degree of focusing of the beam is constructed. The design principles and basic characteristic considerations for electron beam line source consists of parallel plate electrode geometric array as well as a beam power of 35kW are worked out. The dimensions of the beam at the work site are 1.25xl00mm. The gun is designed basically for the study of evaporation and deposition characteristic of refractory metals for laboratory use. However, it may be equally used for melting and casting of these metals. (author)

LNG vapor dispersion prediction with the DEGADIS dense-gas dispersion model. Topical report, April 1988-July 1990. Documentation

International Nuclear Information System (INIS)

Havens, J.; Spicer, T.

1990-09-01

The topical report is one of a series on the development of methods for LNG vapor dispersion prediction for regulatory application. The results indicate that the DEGADIS model is superior both phenomenologically and in performance to the Gaussian line source model promulgated in 49 CFR 193 for LNG vapor dispersion simulation. Availability of the DEGADIS model for VAX and IBM-PC formats provides for wider use of the model and greater potential for industry and regulatory acceptance. The acceptance is seen as an important interim objective while research continues on vapor dispersion estimation methods which provide for effects of vapor detention systems, turbulence induced by plant structure, and plant/area topographical features

Laser systems for on-line laser ion sources

International Nuclear Information System (INIS)

Geppert, Christopher

2008-01-01

Since its initiation in the middle of the 1980s, the resonant ionization laser ion source has been established as a reliable and efficient on-line ion source for radioactive ion beams. In comparison to other on-line ion sources it comprises the advantages of high versatility for the elements to be ionized and of high selectivity and purity for the ion beam generated by resonant laser radiation. Dye laser systems have been the predominant and pioneering working horses for laser ion source applications up to recently, but the development of all-solid-state titanium:sapphire laser systems has nowadays initiated a significant evolution within this field. In this paper an overview of the ongoing developments will be given, which have contributed to the establishment of a number of new laser ion source facilities worldwide during the last five years.

A dispersion modelling system for urban air pollution

Energy Technology Data Exchange (ETDEWEB)

Karppinen, A.; Kukkonen, J.; Nordlund, G.; Rantakrans, E.; Valkama, I.

1998-10-01

An Urban Dispersion Modelling system UDM-FMI, developed at the Finnish Meteorological Institute is described in the report. The modelling system includes a multiple source Gaussian plume model and a meteorological pre-processing model. The dispersion model is an integrated urban scale model, taking into account of all source categories (point, line, area and volume sources). It includes a treatment of chemical transformation (for NO{sub 2}) wet and dry deposition (for SO{sub 2}) plume rise, downwash phenomena and dispersion of inert particles. The model allows also for the influence of a finite mixing height. The model structure is mainly based on the state-of-the-art methodology. The system also computes statistical parameters from the time series, which can be compared to air quality guidelines. The relevant meteorological parameters for the dispersion model are evaluated using data produced by a meteorological pre-processor. The model is based mainly on the energy budget method. Results of national investigations have been used for evaluating climate-dependent parameters. The model utilises the synoptic meteorological observations, radiation records and aerological sounding observations. The model results include the hourly time series of the relevant atmospheric turbulence 51 refs.

Data assimilation on atmospheric dispersion of radioactive materials

DEFF Research Database (Denmark)

Drews, Martin

a new method for on-line estimation of the radionuclide source term, i.e. the amount and composition of the released radionuclides, and the main dispersion parameters, based on radiation monitoring data obtained in the vicinity of the release. The method is based on the extended Kalman filter (EKF...

Stacked dipole line source excitation of active nano-particles

DEFF Research Database (Denmark)

Arslanagic, Samel

This work investigates electromagnetic properties of cylindrical active coated nano-particles excited by a stac- ked electric dipole line source. The nano-particles consist of a silica nano-core, layered by silver, gold, or copper nano-shell. Attention is devoted to the influence of the source...... location and dipole orientation, the gain constant, and the nano-particle material composition on the electromagnetic field distributions and radiated powers. The results are contrasted to those for the magnetic line source illumination of the nano-particles....

Kalman filtration of radiation monitoring data from atmospheric dispersion of radioactive materials

DEFF Research Database (Denmark)

Drews, M.; Lauritzen, B.; Madsen, H.

2004-01-01

A Kalman filter method using off-site radiation monitoring data is proposed as a tool for on-line estimation of the source term for short-range atmospheric dispersion of radioactive materials. The method is based on the Gaussian plume model, in which the plume parameters including the source term...

Modified ensemble Kalman filter for nuclear accident atmospheric dispersion: prediction improved and source estimated.

Science.gov (United States)

Zhang, X L; Su, G F; Yuan, H Y; Chen, J G; Huang, Q Y

2014-09-15

Atmospheric dispersion models play an important role in nuclear power plant accident management. A reliable estimation of radioactive material distribution in short range (about 50 km) is in urgent need for population sheltering and evacuation planning. However, the meteorological data and the source term which greatly influence the accuracy of the atmospheric dispersion models are usually poorly known at the early phase of the emergency. In this study, a modified ensemble Kalman filter data assimilation method in conjunction with a Lagrangian puff-model is proposed to simultaneously improve the model prediction and reconstruct the source terms for short range atmospheric dispersion using the off-site environmental monitoring data. Four main uncertainty parameters are considered: source release rate, plume rise height, wind speed and wind direction. Twin experiments show that the method effectively improves the predicted concentration distribution, and the temporal profiles of source release rate and plume rise height are also successfully reconstructed. Moreover, the time lag in the response of ensemble Kalman filter is shortened. The method proposed here can be a useful tool not only in the nuclear power plant accident emergency management but also in other similar situation where hazardous material is released into the atmosphere. Copyright © 2014 Elsevier B.V. All rights reserved.

Direct and inverse source problems for a space fractional advection dispersion equation

KAUST Repository

Aldoghaither, Abeer; Laleg-Kirati, Taous-Meriem; Liu, Da Yan

2016-01-01

In this paper, direct and inverse problems for a space fractional advection dispersion equation on a finite domain are studied. The inverse problem consists in determining the source term from final observations. We first derive the analytic

Reconstructing source-sink dynamics in a population with a pelagic dispersal phase.

Directory of Open Access Journals (Sweden)

Kun Chen

Full Text Available For many organisms, the reconstruction of source-sink dynamics is hampered by limited knowledge of the spatial assemblage of either the source or sink components or lack of information on the strength of the linkage for any source-sink pair. In the case of marine species with a pelagic dispersal phase, these problems may be mitigated through the use of particle drift simulations based on an ocean circulation model. However, when simulated particle trajectories do not intersect sampling sites, the corroboration of model drift simulations with field data is hampered. Here, we apply a new statistical approach for reconstructing source-sink dynamics that overcomes the aforementioned problems. Our research is motivated by the need for understanding observed changes in jellyfish distributions in the eastern Bering Sea since 1990. By contrasting the source-sink dynamics reconstructed with data from the pre-1990 period with that from the post-1990 period, it appears that changes in jellyfish distribution resulted from the combined effects of higher jellyfish productivity and longer dispersal of jellyfish resulting from a shift in the ocean circulation starting in 1991. A sensitivity analysis suggests that the source-sink reconstruction is robust to typical systematic and random errors in the ocean circulation model driving the particle drift simulations. The jellyfish analysis illustrates that new insights can be gained by studying structural changes in source-sink dynamics. The proposed approach is applicable for the spatial source-sink reconstruction of other species and even abiotic processes, such as sediment transport.

Atmospheric dispersion prediction and source estimation of hazardous gas using artificial neural network, particle swarm optimization and expectation maximization

Science.gov (United States)

Qiu, Sihang; Chen, Bin; Wang, Rongxiao; Zhu, Zhengqiu; Wang, Yuan; Qiu, Xiaogang

2018-04-01

Hazardous gas leak accident has posed a potential threat to human beings. Predicting atmospheric dispersion and estimating its source become increasingly important in emergency management. Current dispersion prediction and source estimation models cannot satisfy the requirement of emergency management because they are not equipped with high efficiency and accuracy at the same time. In this paper, we develop a fast and accurate dispersion prediction and source estimation method based on artificial neural network (ANN), particle swarm optimization (PSO) and expectation maximization (EM). The novel method uses a large amount of pre-determined scenarios to train the ANN for dispersion prediction, so that the ANN can predict concentration distribution accurately and efficiently. PSO and EM are applied for estimating the source parameters, which can effectively accelerate the process of convergence. The method is verified by the Indianapolis field study with a SF6 release source. The results demonstrate the effectiveness of the method.

Dispersive XAS on a High Brilliance Source: Highlights and Future Opportunities

International Nuclear Information System (INIS)

Pascarelli, S.; Aquilanti, G.; Guilera, G.; Mathon, O.; Newton, M. A.; Trapananti, A.; Dubrovinsky, L.; Munoz, M.; Pasquale, M.

2007-01-01

Energy Dispersive X-ray Absorption Spectroscopy is a now a well-established method which has been applied to a broad range of applications. Ten years from the construction of beamline ID24 at the ESRF, the first dispersive XAS spectrometer using undulator radiation on a third generation source, we report an overview of recent results in very diverse fields of research, ranging from automotive catalysts to magnetism at extreme conditions. We also illustrate how pushing the instrument to its limits has opened new opportunities, such as an enhanced sensitivity to detection of tiny atomic displacements and the potential for micro-probe redox and speciation imaging

Pollutant Dispersion Modeling in Natural Streams Using the Transmission Line Matrix Method

Directory of Open Access Journals (Sweden)

Safia Meddah

2015-09-01

Full Text Available Numerical modeling has become an indispensable tool for solving various physical problems. In this context, we present a model of pollutant dispersion in natural streams for the far field case where dispersion is considered longitudinal and one-dimensional in the flow direction. The Transmission Line Matrix (TLM, which has earned a reputation as powerful and efficient numerical method, is used. The presented one-dimensional TLM model requires a minimum input data and provides a significant gain in computing time. To validate our model, the results are compared with observations and experimental data from the river Severn (UK. The results show a good agreement with experimental data. The model can be used to predict the spatiotemporal evolution of a pollutant in natural streams for effective and rapid decision-making in a case of emergency, such as accidental discharges in a stream with a dynamic similar to that of the river Severn (UK.

Direct and inverse source problems for a space fractional advection dispersion equation

KAUST Repository

Aldoghaither, Abeer

2016-05-15

In this paper, direct and inverse problems for a space fractional advection dispersion equation on a finite domain are studied. The inverse problem consists in determining the source term from final observations. We first derive the analytic solution to the direct problem which we use to prove the uniqueness and the unstability of the inverse source problem using final measurements. Finally, we illustrate the results with a numerical example.

High intensity line source for x-ray spectrometer calibration

International Nuclear Information System (INIS)

Thoe, R.S.

1986-06-01

A high intensity electron-impact x-ray source using a one-dimensional Pierce lens has been built for the purpose of calibrating a bent crystal x-ray spectrometer. This source focuses up to 100 mA of 20-keV electrons to a line on a liquid-cooled anode. The line (which can serve as a virtual slit for the spectrometer) measures approximately 800 μ x 2 cm. The source is portable and therefore adaptable to numerous types of spectrometer applications. One particular application, the calibration of a high resolution (r = 10 4 ) time-resolved cyrstal spectrometer, will be discussed in detail

Ion source and injection line for high intensity medical cyclotron

Science.gov (United States)

Jia, XianLu; Guan, Fengping; Yao, Hongjuan; Zhang, TianJue; Yang, Jianjun; Song, Guofang; Ge, Tao; Qin, Jiuchang

2014-02-01

A 14 MeV high intensity compact cyclotron, CYCIAE-14, was built at China Institute of Atomic Energy (CIAE). An injection system based on the external H- ion source was used on CYCIAE-14 so as to provide high intensity beam, while most positron emission tomography cyclotrons adopt internal ion source. A beam intensity of 100 μA/14 MeV was extracted from the cyclotron with a small multi-cusp H- ion source (CIAE-CH-I type) and a short injection line, which the H- ion source of 3 mA/25 keV H- beam with emittance of 0.3π mm mrad and the injection line of with only 1.2 m from the extraction of ion source to the medial plane of the cyclotron. To increase the extracted beam intensity of the cyclotron, a new ion source (CIAE-CH-II type) of 9.1 mA was used, with maximum of 500 μA was achieved from the cyclotron. The design and test results of the ion source and injection line optimized for high intensity acceleration will be given in this paper.

Multiple source genes of HAmo SINE actively expanded and ongoing retroposition in cyprinid genomes relying on its partner LINE

Directory of Open Access Journals (Sweden)

Gan Xiaoni

2010-04-01

Full Text Available Abstract Background We recently characterized HAmo SINE and its partner LINE in silver carp and bighead carp based on hybridization capture of repetitive elements from digested genomic DNA in solution using a bead-probe 1. To reveal the distribution and evolutionary history of SINEs and LINEs in cyprinid genomes, we performed a multi-species search for HAmo SINE and its partner LINE using the bead-probe capture and internal-primer-SINE polymerase chain reaction (PCR techniques. Results Sixty-seven full-size and 125 internal-SINE sequences (as well as 34 full-size and 9 internal sequences previously reported in bighead carp and silver carp from 17 species of the family Cyprinidae were aligned as well as 14 new isolated HAmoL2 sequences. Four subfamilies (type I, II, III and IV, which were divided based on diagnostic nucleotides in the tRNA-unrelated region, expanded preferentially within a certain lineage or within the whole family of Cyprinidae as multiple active source genes. The copy numbers of HAmo SINEs were estimated to vary from 104 to 106 in cyprinid genomes by quantitative RT-PCR. Over one hundred type IV members were identified and characterized in the primitive cyprinid Danio rerio genome but only tens of sequences were found to be similar with type I, II and III since the type IV was the oldest subfamily and its members dispersed in almost all investigated cyprinid fishes. For determining the taxonomic distribution of HAmo SINE, inter-primer SINE PCR was conducted in other non-cyprinid fishes, the results shows that HAmo SINE- related sequences may disperse in other families of order Cypriniforms but absent in other orders of bony fishes: Siluriformes, Polypteriformes, Lepidosteiformes, Acipenseriformes and Osteoglossiforms. Conclusions Depending on HAmo LINE2, multiple source genes (subfamilies of HAmo SINE actively expanded and underwent retroposition in a certain lineage or within the whole family of Cyprinidae. From this

Phase II beam lines at the National Synchrotron Light Source

International Nuclear Information System (INIS)

Thomlinson, W.

1984-06-01

The expansion of the National Synchrotron Light Source has been funded by the US Department of Energy. The Phase II program consists of both increased conventional facilities and six new beam lines. In this paper, an overview of the six beam lines which will be constructed during Phase II is presented. For five of the lines special radiation sources are necessary and the designs of four of the devices are complete. The relevant parameters of the insertion devices under construction and development are presented

Source Lines Counter (SLiC) Version 4.0

Science.gov (United States)

Monson, Erik W.; Smith, Kevin A.; Newport, Brian J.; Gostelow, Roli D.; Hihn, Jairus M.; Kandt, Ronald K.

2011-01-01

Source Lines Counter (SLiC) is a software utility designed to measure software source code size using logical source statements and other common measures for 22 of the programming languages commonly used at NASA and the aerospace industry. Such metrics can be used in a wide variety of applications, from parametric cost estimation to software defect analysis. SLiC has a variety of unique features such as automatic code search, automatic file detection, hierarchical directory totals, and spreadsheet-compatible output. SLiC was written for extensibility; new programming language support can be added with minimal effort in a short amount of time. SLiC runs on a variety of platforms including UNIX, Windows, and Mac OSX. Its straightforward command-line interface allows for customization and incorporation into the software build process for tracking development metrics. T

Identification and elucidation of anthropogenic source contribution in PM10 pollutant: Insight gain from dispersion and receptor models.

Science.gov (United States)

Roy, Debananda; Singh, Gurdeep; Yadav, Pankaj

2016-10-01

Source apportionment study of PM 10 (Particulate Matter) in a critically polluted area of Jharia coalfield, India has been carried out using Dispersion model, Principle Component Analysis (PCA) and Chemical Mass Balance (CMB) techniques. Dispersion model Atmospheric Dispersion Model (AERMOD) was introduced to simplify the complexity of sources in Jharia coalfield. PCA and CMB analysis indicates that monitoring stations near the mining area were mainly affected by the emission from open coal mining and its associated activities such as coal transportation, loading and unloading of coal. Mine fire emission also contributed a considerable amount of particulate matters in monitoring stations. Locations in the city area were mostly affected by vehicular, Liquid Petroleum Gas (LPG) & Diesel Generator (DG) set emissions, residential, and commercial activities. The experimental data sampling and their analysis could aid understanding how dispersion based model technique along with receptor model based concept can be strategically used for quantitative analysis of Natural and Anthropogenic sources of PM 10 . Copyright © 2016. Published by Elsevier B.V.

Introducing Product Lines through Open Source Tools

OpenAIRE

Haugen, Øystein

2008-01-01

We present an approach to introducing product lines to companies that lower their initial risk by applying open source tools and a smooth learning curve into the use and creation of domain specific modeling combined with standardized variability modeling.

On-line sources of toxicological information in Canada

International Nuclear Information System (INIS)

Racz, William J.; Ecobichon, Donald J.; Baril, Marc

2003-01-01

This paper will provide an overview of the on-line resources available in toxicology in Canada. It will describe a brief history of The Society of Toxicology of Canada, with reference to other societies and also provide information on education, research and other resources related to toxicology. Toxicology in Canada emerged as a distinct and vibrant discipline following the thalidomide tragedy of the 1960s. In the pharmaceutical industry and government, toxicology was readily established as an essential component of drug development and safety, and as the need for toxicologists expanded, training programs were established, usually in collaboration with departments of pharmacology. In the last two to three decades other disciplines, environmental biology, analytical chemistry and epidemiology joined the ranks of toxicology. The on-line sources of toxicology information are rapidly expanding. This article describes those sources considered by the authors to be important from a national and international perspective. The majority of these sources are professional organizations and government agencies

Air quality dispersion models from energy sources

International Nuclear Information System (INIS)

Lazarevska, Ana

1996-01-01

Along with the continuing development of new air quality models that cover more complex problems, in the Clean Air Act, legislated by the US Congress, a consistency and standardization of air quality model applications were encouraged. As a result, the Guidelines on Air Quality Models were published, which are regularly reviewed by the Office of Air Quality Planning and Standards, EPA. These guidelines provide a basis for estimating the air quality concentrations used in accessing control strategies as well as defining emission limits. This paper presents a review and analysis of the recent versions of the models: Simple Terrain Stationary Source Model; Complex Terrain Dispersion Model; Ozone,Carbon Monoxide and Nitrogen Dioxide Models; Long Range Transport Model; Other phenomenon Models:Fugitive Dust/Fugitive Emissions, Particulate Matter, Lead, Air Pathway Analyses - Air Toxic as well as Hazardous Waste. 8 refs., 4 tabs., 2 ills

Effects of dispersion on electromagnetic parameters of tape-helix Blumlein pulse forming line of accelerator

International Nuclear Information System (INIS)

Zhang, Y.; Liu, J.L.; Feng, J.H.

2012-01-01

In this paper, the tape-helix model is introduced in the field of intense electron beam accelerator to analyze the dispersion effects on the electromagnetic parameters of helical Blumlein pulse forming line (PFL). Work band and dispersion relation of the PFL are analyzed, and the normalized coefficients of spatial harmonics are calculated. Dispersion effects on the important electromagnetic parameters of PFL, such as phase velocity, slow-wave coefficient, electric length and pulse duration, are analyzed as the central topic. In the PFL, electromagnetic waves with different frequencies in the work band of PFL have almost the same phase velocity. When de-ionized water, transformer oil and air are used as the PFL filling dielectric, respectively, the pulse duration of the helical Blumlein PFL is calculated as 479.6 ns, 81.1 ns and 53.1 ns in order. Electromagnetic wave simulation and experiments are carried out to demonstrate the theoretical calculations of the electric length and pulse duration which directly describe the phase velocity and dispersion of the PFL. Simulation results prove the theoretical analysis and calculation on pulse duration. Experiment is carried out based on the tape-helix Blumlein PFL and magnetic switch system. Experimental results show that the pulse durations are tested as 460 ns, 79 ns and 49 ns in order when de-ionized water, transformer oil and air are used respectively. Experimental results basically demonstrate the theoretical calculations and the analyses of dispersion. (authors)

Noise study of all-normal dispersion supercontinuum sources for potential application in optical coherence tomography

Science.gov (United States)

Gonzalo, I. B.; Engelsholm, R. D.; Bang, O.

2018-03-01

Commercially available silica-fiber-based and ultra-broadband supercontinuum (SC) sources are typically generated by pumping close to the zero-dispersion wavelength (ZDW) of a photonic crystal fiber (PCF), using high-power picosecond or nanosecond laser pulses. Despite the extremely broad bandwidths, such sources are characterized by large intensity fluctuations, limiting their performance for applications in imaging such as optical coherence tomography (OCT). An approach to eliminate the influence of noise sensitive effects is to use a so-called all-normal dispersion (ANDi) fiber, in which the dispersion is normal for all the wavelengths of interest. Pumping these types of fibers with short enough femtosecond pulses allows to suppress stimulated Raman scattering (SRS), which is known to be as noisy process as modulation instability (MI), and coherent SC is generated through self-phase modulation (SPM) and optical wave breaking (OWB). In this study, we show the importance of the pump laser and fiber parameters in the design of low-noise ANDi based SC sources, for application in OCT. We numerically investigate the pulse-to-pulse fluctuations of the SC, calculating the relative intensity noise (RIN) as a function of the pump pulse duration and fiber length. Furthermore, we experimentally demonstrate the role of the fiber length on the RIN of the ANDi SC, validating the results calculated numerically. In the end, we compare the RIN of a commercial SC source based on MI and the ANDi SC source developed here, which shows better noise performance when it is carefully designed.

Dispersion Measure Variation of Repeating Fast Radio Burst Sources

Energy Technology Data Exchange (ETDEWEB)

Yang, Yuan-Pei; Zhang, Bing, E-mail: yypspore@gmail.com, E-mail: zhang@physics.unlv.edu [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

2017-09-20

The repeating fast radio burst (FRB) 121102 was recently localized in a dwarf galaxy at a cosmological distance. The dispersion measure (DM) derived for each burst from FRB 121102 so far has not shown significant evolution, even though an apparent increase was recently seen with newly detected VLA bursts. It is expected that more repeating FRB sources may be detected in the future. In this work, we investigate a list of possible astrophysical processes that might cause DM variation of a particular FRB source. The processes include (1) cosmological scale effects such as Hubble expansion and large-scale structure fluctuations; (2) FRB local effects such as gas density fluctuation, expansion of a supernova remnant (SNR), a pulsar wind nebula, and an H ii region; and (3) the propagation effect due to plasma lensing. We find that the DM variations contributed by the large-scale structure are extremely small, and any observable DM variation is likely caused by the plasma local to the FRB source. In addition to mechanisms that decrease DM over time, we suggest that an FRB source in an expanding SNR around a nearly neutral ambient medium during the deceleration (Sedov–Taylor and snowplow) phases or in a growing H ii region can increase DM. Some effects (e.g., an FRB source moving in an H ii region or plasma lensing) can produce either positive or negative DM variations. Future observations of DM variations of FRB 121102 and other repeating FRB sources can provide important clues regarding the physical origin of these sources.

Dispersion Measure Variation of Repeating Fast Radio Burst Sources

International Nuclear Information System (INIS)

Yang, Yuan-Pei; Zhang, Bing

2017-01-01

The repeating fast radio burst (FRB) 121102 was recently localized in a dwarf galaxy at a cosmological distance. The dispersion measure (DM) derived for each burst from FRB 121102 so far has not shown significant evolution, even though an apparent increase was recently seen with newly detected VLA bursts. It is expected that more repeating FRB sources may be detected in the future. In this work, we investigate a list of possible astrophysical processes that might cause DM variation of a particular FRB source. The processes include (1) cosmological scale effects such as Hubble expansion and large-scale structure fluctuations; (2) FRB local effects such as gas density fluctuation, expansion of a supernova remnant (SNR), a pulsar wind nebula, and an H ii region; and (3) the propagation effect due to plasma lensing. We find that the DM variations contributed by the large-scale structure are extremely small, and any observable DM variation is likely caused by the plasma local to the FRB source. In addition to mechanisms that decrease DM over time, we suggest that an FRB source in an expanding SNR around a nearly neutral ambient medium during the deceleration (Sedov–Taylor and snowplow) phases or in a growing H ii region can increase DM. Some effects (e.g., an FRB source moving in an H ii region or plasma lensing) can produce either positive or negative DM variations. Future observations of DM variations of FRB 121102 and other repeating FRB sources can provide important clues regarding the physical origin of these sources.

Measurement of the dispersion of radiation from a steady cosmological source

International Nuclear Information System (INIS)

Lieu, Richard; Duan, Lingze; Kibble, T. W. B.

2013-01-01

The 'missing baryons' of the near universe are believed to be principally in a partially ionized state. Although passing electromagnetic waves are dispersed by the plasma, the effect has hitherto not been utilized as a means of detection because it is generally believed that a successful observation requires the background source to be highly variable, i.e., the class of sources that could potentially deliver a verdict is limited. We argue in two stages that this condition is not necessary. First, by modeling the fluctuations on macroscopic scales as interference between wave packets, we show that, in accordance with the ideas advanced by Einstein in 1917, both the behavior of photons as bosons (i.e., the intensity variance has contributions from Poisson and phase noise) and the van-Cittert-Zernike theorem are a consequence of wave-particle duality. Nevertheless, we then point out that, in general, the variance on some macroscopic timescale τ consists of (1) a main contributing term ∝1/τ, plus (2) a small negative term ∝1/τ 2 due to the finite size of the wave packets. If the radiation passes through a dispersive medium, this size will be enlarged well beyond its vacuum minimum value of Δt ≈ 1/Δν, leading to a more negative (2) term (while (1) remains unchanged), and hence a suppression of the variance wrt the vacuum scenario. The phenomenon, which is typically at a few parts in 10 5 level, enables one to measure cosmological dispersion in principle. Signal-to-noise estimates, along with systematic issues and how to overcome them, will be presented.

In-line micro-matrix solid-phase dispersion extraction for simultaneous separation and extraction of Sudan dyes in different spices.

Science.gov (United States)

Rajabi, Maryam; Sabzalian, Sedigheh; Barfi, Behruz; Arghavani-Beydokhti, Somayeh; Asghari, Alireza

2015-12-18

A novel, simple, fast, and miniaturized method, termed in-line micro-matrix solid-phase dispersion (in-line MMSPD), coupled with high performance liquid chromatography (HPLC) was developed for the simultaneous extraction and determination of Sudan dyes (i.e. Sudan I-IV, Sudan orange G, Sudan black B, and Sudan red G) with the aid of an experimental design strategy. In this method, a matrix solid-phase dispersion (MSPD) column including a suitable mixture of polar sorbents was inserted in the mobile phase pathway, and while the interfering compounds were retained, the analytes were eluted and entered into the analytical column. In this way, the extraction, elution, and separation of the analytes were performed sequentially. Under the optimal experimental conditions (including the amount of sample, 0.0426g; amount of dispersant phase, 0.0216g of florisil, 0.0227g of silica, 0.0141g of alumina; and blending time, 112s), the limits of detection (LODs), limits of quantification, linear dynamic ranges, and recoveries were obtained to be 0.3-15.3μgkg(-1), 1-50μgkg(-1), 50-28,000μgkg(-1), and 94.5-99.1%, respectively. The results obtained showed that determination of the selected Sudan dyes in food samples using an enough sensitive and a simple analytically validated method like in-line MMSPD may offer a suitable screening method, which could be useful for food analysis and adulteration. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of dispersity of crushed granite

International Nuclear Information System (INIS)

Liu Dejun; Fan Xianhua; Zhang Yingjie; Yao Jun; Zhou Duo; Wang Yong

2004-01-01

The experimental crushed granite column breakthrough curves, using 99 Tc as spike tracer and 3 H as invariant tracer, are analyzed by different linear regression techniques. Dispersity of crushed granite and retardation factor of 99 TcO 4 - on the crushed granite are determined simultaneously by one linear regression technique. Dispersity of crushed granite is also obtained with 3 H as invariant tracer by the other linear regression technique. The dispersities found by spike source and invariant source methods are compared. The experimental results show that the dispersity found by spike source method is close to that found by invariant source method. It indicates that dispersity is only the characteristic of dispersion medium

Determination of dispersity of crushed granite

International Nuclear Information System (INIS)

Liu, D.J.; Fan, X.H.

2005-01-01

Experimental crushed granite column breakthrough curves, using 99 Tc as spike tracer and 3 H as invariant tracer, were analyzed by different linear regression techniques. Dispersity of crushed granite and the retardation factor of 99 TcO 4 - on the crushed granite were determined simultaneously by one linear regression. Dispersity of crushed granite was also obtained with 3 H as invariant tracer by the other linear regression. The dispersities found by spike source and invariant source methods are compared. Experimental results show that the dispersity found by the spike source method is close to that found by the invariant source method. This indicates that dispersity is only a characteristic of the dispersion medium. (author)

Nonlinear estimation-based dipole source localization for artificial lateral line systems

International Nuclear Information System (INIS)

Abdulsadda, Ahmad T; Tan Xiaobo

2013-01-01

As a flow-sensing organ, the lateral line system plays an important role in various behaviors of fish. An engineering equivalent of a biological lateral line is of great interest to the navigation and control of underwater robots and vehicles. A vibrating sphere, also known as a dipole source, can emulate the rhythmic movement of fins and body appendages, and has been widely used as a stimulus in the study of biological lateral lines. Dipole source localization has also become a benchmark problem in the development of artificial lateral lines. In this paper we present two novel iterative schemes, referred to as Gauss–Newton (GN) and Newton–Raphson (NR) algorithms, for simultaneously localizing a dipole source and estimating its vibration amplitude and orientation, based on the analytical model for a dipole-generated flow field. The performance of the GN and NR methods is first confirmed with simulation results and the Cramer–Rao bound (CRB) analysis. Experiments are further conducted on an artificial lateral line prototype, consisting of six millimeter-scale ionic polymer–metal composite sensors with intra-sensor spacing optimized with CRB analysis. Consistent with simulation results, the experimental results show that both GN and NR schemes are able to simultaneously estimate the source location, vibration amplitude and orientation with comparable precision. Specifically, the maximum localization error is less than 5% of the body length (BL) when the source is within the distance of one BL. Experimental results have also shown that the proposed schemes are superior to the beamforming method, one of the most competitive approaches reported in literature, in terms of accuracy and computational efficiency. (paper)

Does Light from Steady Sources Bear Any Observable Imprint of the Dispersive Intergalactic Medium?

Science.gov (United States)

Lieu, Richard; Duan, Lingze

2018-02-01

There has recently been some interest in the prospect of detecting ionized intergalactic baryons by examining the properties of incoherent light from background cosmological sources, namely quasars. Although the paper by Lieu et al. proposed a way forward, it was refuted by the later theoretical work of Hirata & McQuinn and the observational study of Hales et al. In this paper we investigate in detail the manner in which incoherent radiation passes through a dispersive medium both from the frameworks of classical and quantum electrodynamics, leading us to conclude that the premise of Lieu et al. would only work if the pulses involved are genuinely classical ones containing many photons per pulse; unfortunately, each photon must not be treated as a pulse that is susceptible to dispersive broadening. We are nevertheless able to change the tone of the paper at this juncture by pointing out that because current technology allows one to measure the phase of individual modes of radio waves from a distant source, the most reliable way of obtaining irrefutable evidence of dispersion, namely via the detection of its unique signature of a quadratic spectral phase, may well be already accessible. We demonstrate how this technique is only applied to measure the column density of the ionized intergalactic medium.

Turbulent Plume Dispersion over Two-dimensional Idealized Urban Street Canyons

Science.gov (United States)

Wong, C. C. C.; Liu, C. H.

2012-04-01

Human activities are the primary pollutant sources which degrade the living quality in the current era of dense and compact cities. A simple and reasonably accurate pollutant dispersion model is helpful to reduce pollutant concentrations in city or neighborhood scales by refining architectural design or urban planning. The conventional method to estimate the pollutant concentration from point/line sources is the Gaussian plume model using empirical dispersion coefficients. Its accuracy is pretty well for applying to rural areas. However, the dispersion coefficients only account for the atmospheric stability and streamwise distance that often overlook the roughness of urban surfaces. Large-scale buildings erected in urban areas significantly modify the surface roughness that in turn affects the pollutant transport in the urban canopy layer (UCL). We hypothesize that the aerodynamic resistance is another factor governing the dispersion coefficient in the UCL. This study is thus conceived to study the effects of urban roughness on pollutant dispersion coefficients and the plume behaviors. Large-eddy simulations (LESs) are carried out to examine the plume dispersion from a ground-level pollutant source over idealized 2D street canyons in neutral stratification. Computations with a wide range of aspect ratios (ARs), including skimming flow to isolated flow regimes, are conducted. The vertical profiles of pollutant distribution for different values of friction factor are compared that all reach a self-similar Gaussian shape. Preliminary results show that the pollutant dispersion is closely related to the friction factor. For relatively small roughness, the factors of dispersion coefficient vary linearly with the friction factor until the roughness is over a certain level. When the friction factor is large, its effect on the dispersion coefficient is less significant. Since the linear region covers at least one-third of the full range of friction factor in our empirical

Source strength and dispersion of CO2 releases from high-pressure pipelines: CFD model using real gas equation of state

International Nuclear Information System (INIS)

Liu, Xiong; Godbole, Ajit; Lu, Cheng; Michal, Guillaume; Venton, Philip

2014-01-01

Highlights: • Validated CFD models for decompression and dispersion of CO 2 releases from pipelines. • Incorporation of real gas EOS into CFD code for source strength estimation. • Demonstration of better performance of SST k–ω turbulence model for jet flow. • Demonstration of better performance of real gas EOS compared to ideal gas EOS. • Demonstration of superiority of CFD models over a commercial risk assessment package. - Abstract: Transportation of CO 2 in high-pressure pipelines forms a crucial link in the ever-increasing application of Carbon Capture and Storage (CCS) technologies. An unplanned release of CO 2 from a pipeline presents a risk to human and animal populations and the environment. Therefore it is very important to develop a deeper understanding of the atmospheric dispersion of CO 2 before the deployment of CO 2 pipelines, to allow the appropriate safety precautions to be taken. This paper presents a two-stage Computational Fluid Dynamics (CFD) study developed (1) to estimate the source strength, and (2) to simulate the subsequent dispersion of CO 2 in the atmosphere, using the source strength estimated in stage (1). The Peng–Robinson (PR) EOS was incorporated into the CFD code. This enabled accurate modelling of the CO 2 jet to achieve more precise source strength estimates. The two-stage simulation approach also resulted in a reduction in the overall computing time. The CFD models were validated against experimental results from the British Petroleum (BP) CO 2 dispersion trials, and also against results produced by the risk management package Phast. Compared with the measurements, the CFD simulation results showed good agreement in both source strength and dispersion profile predictions. Furthermore, the effect of release direction on the dispersion was studied. The presented research provides a viable method for the assessment of risks associated with CCS

Non-uniform dwell times in line source high dose rate brachytherapy: physical and radiobiological considerations

International Nuclear Information System (INIS)

Jones, B.; Tan, L.T.; Freestone, G.; Bleasdale, C.; Myint, S.; Littler, J.

1994-01-01

The ability to vary source dwell times in high dose rate (HDR) brachytherapy allows for the use of non-uniform dwell times along a line source. This may have advantages in the radical treatment of tumours depending on individual tumour geometry. This study investigates the potential improvements in local tumour control relative to adjacent normal tissue isoeffects when intratumour source dwell times are increased along the central portion of a line source (technique A) in radiotherapy schedules which include a relatively small component of HDR brachytherapy. Such a technique is predicted to increase the local control for tumours of diameters ranging between 2 cm and 4 cm by up to 11% compared with a technique in which there are uniform dwell times along the line source (technique B). There is no difference in the local control rates for the two techniques when used to treat smaller tumours. Normal tissue doses are also modified by the technique used. Technique A produces higher normal tissue doses at points perpendicular to the centre of the line source and lower dose at points nearer the ends of the line source if the prescription point is not in the central plane of the line source. Alternatively, if the dose is prescribed at a point in the central plane of the line source, the dose at all the normal tissue points are lower when technique A is used. (author)

Comparative Study on Radiological Impact Due To Direct Exposure to a Radiological Dispersal Device Using A Sealed Radiation Source

International Nuclear Information System (INIS)

Margeanu, C.A.

2011-01-01

Nowadays, one of the most serious terrorist threats implies radiological dispersal devices (RDDs), the so-called dirty bombs, that combine a conventional explosive surrounded by an inflammatory material (like thermit) with radioactive material. The paper objective is to evaluate the radiological impact due to direct exposure to a RDD using a sealed radiation source (used for medical and industrial applications) as radioactive material. The simulations were performed for 60Co, 137Cs and 192Ir radiation sources. In order to model the contamination potential level and radiation exposure due to radioactive material spreading from RDD, Lawrence Livermore National Laboratory's HOTSPOT 2.07 computer code was used. The worst case scenario has been considered, calculations being performed for two radioactive material dispersion models, namely General radioactive Plume and General Explosion. Following parameters evolution with distance from the radiation source was investigated: total effective dose equivalent, time-integrated air concentration, ground surface deposition and ground shine dose rates. Comparisons between considered radiation sources and radioactive material dispersion models have been performed. The most drastic effects on population and the environment characterize 60Co sealed radiation source use in RDD.

Noise study of all-normal dispersion supercontinuum sources for potential application in optical coherence tomography

DEFF Research Database (Denmark)

Bravo Gonzalo, Ivan; Engelsholm, Rasmus Dybbro; Bang, Ole

2017-01-01

bandwidths, such sources are characterized by large intensity fluctuations, limiting their performance for applications in imaging such as optical coherence tomography (OCT). An approach to eliminate the influence of noise sensitive effects is to use a so-called all-normal dispersion (ANDi) fiber, in which...... the dispersion is normal for all the wavelengths of interest. Pumping these types of fibers with short enough femtosecond pulses allows to suppress stimulated Raman scattering (SRS), which is known to be as noisy process as modulation instability (MI), and coherent SC is generated through self-phase modulation...... (SPM) and optical wave breaking (OWB). In this study, we show the importance of the pump laser and fiber parameters in the design of low-noise ANDi based SC sources, for application in OCT. We numerically investigate the pulse-to-pulse fluctuations of the SC, calculating the relative intensity noise...

A dispersion-balanced Discrete Fourier Transform of repetitive pulse sequences using temporal Talbot effect

Science.gov (United States)

Fernández-Pousa, Carlos R.

2017-11-01

We propose a processor based on the concatenation of two fractional temporal Talbot dispersive lines with balanced dispersion to perform the DFT of a repetitive electrical sequence, for its use as a controlled source of optical pulse sequences. The electrical sequence is used to impart the amplitude and phase of a coherent train of optical pulses by use of a modulator placed between the two Talbot lines. The proposal has been built on a representation of the action of fractional Talbot effect on repetitive pulse sequences and a comparison with related results and proposals. It is shown that the proposed system is reconfigurable within a few repetition periods, has the same processing rate as the input optical pulse train, and requires the same technical complexity in terms of dispersion and pulse width as the standard, passive pulse-repetition rate multipliers based on fractional Talbot effect.

Reduction of the environmental concentration of air pollutants by proper geometrical orientation of industrial line sources

International Nuclear Information System (INIS)

Tadmor, J.

1980-01-01

An account is given of an Israeli study of two line sources, one composed of 10 and the other of 20 individual sources. The height of release ranged from 15.7 to 39.6 m, with a uniform rate of release of a gaseous pollutant of 1 Ci/s for each source. Average pollutant concentration was plotted as a function of the rotation angle of the line sources. Reduction of pollutant concentration by a particular rotation of the line sources attained values of up to 50%. At certain rotation angles of the line sources, the environmental concentration was lower even as compared with a single high source. Results also depended on atmospheric conditions. It is suggested that considering the increase in cost of augmenting the height of release as a means of reducing the air pollutant concentration, determination of the optimum geometric orientation of the line sources should be considered as an economical means of improving environmental air quality. (U.K.)

Modification of the U-line of the RHIC injection line

International Nuclear Information System (INIS)

Xu, Jianming.

1991-09-01

The parameters of the U-line of the RHIC injection line with low β waist are described. In that lattice, the location of SA is not dispersion free and 14 quadrupoles are needed. This line has been modified to move SA to a dispersion free region (after the 8-degree bend), the length and maximum gradient of quadrupoles have been adjusted to fit the existing quadrupole parameters and the number of quadrupoles is reduced to 12. 2 refs., 3 tabs

Rapidly locating sources and predicting contaminant dispersion in buildings

International Nuclear Information System (INIS)

Sohn, Michael D.; Reynolds, Pamela; Gadgil, Ashok J.; Sextro, Richard G.

2002-01-01

Contaminant releases in or near a building can lead to significant human exposures unless prompt response measures are taken. However, selecting the proper response depends in part on knowing the source locations, the amounts released, and the dispersion characteristics of the pollutants. We present an approach that estimates this information in real time. It uses Bayesian statistics to interpret measurements from sensors placed in the building yielding best estimates and uncertainties for the release conditions, including the operating state of the building. Because the method is fast, it continuously updates the estimates as measurements stream in from the sensors. We show preliminary results for characterizing a gas release in a three-floor, multi-room building at the Dugway Proving Grounds, Utah, USA

The determination of an unknown source for a space fractional advection dispersion equation

KAUST Repository

Aldoghaither, Abeer

2014-09-01

In this paper, we are interested in the estimation of the source term for a space fractional advection dispersion equation using concentration and flux measurements at final time. An example of application is the identification of contamination source in groundwater transport. We propose to use the socalled modulating functions method which has been introduced for parameters estimation. This method allows to transfer the estimation problem into solving a system of algebraic equations. Numerical examples are given to illustrate the effectiveness and the robustness of the proposed method. Finally, a comparison between a Tikhonov-based optimization method and the modulating functions approach is presented.

Turbulent transport of passive scalar behind line sources in an unstably stratified open channel flow

Energy Technology Data Exchange (ETDEWEB)

Liu, Chun-Ho [The Hong Kong Polytechnic University, Kowloon (Hong Kong). Department of Building and Real Estate; Leung, Dennis Y.C. [The University of Hong Kong (Hong Kong). Department of Mechanical Engineering

2006-11-15

This study employs a direct numerical simulation (DNS) technique to study the flow, turbulence structure, and passive scalar plume transport behind line sources in an unstably stratified open channel flow. The scalar transport behaviors for five emission heights (z{sub s}=0, 0.25H, 0.5H, 0.75H, and H, where H is the channel height) at a Reynolds number of 3000, a Prandtl number and a Schmidt number of 0.72, and a Richardson number of -0.2 are investigated. The vertically meandering mean plume heights and dispersion coefficients calculated by the current DNS model agree well with laboratory results and field measurements in literature. It is found that the plume meandering is due to the movement of the positive and negative vertical turbulent scalar fluxes above and below the mean plume heights, respectively. These findings help explaining the plume meandering mechanism in the unstably stratified atmospheric boundary layer. (author)

Mantle cloaks for elliptical cylinders excited by an electric line source

DEFF Research Database (Denmark)

Kaminski, Piotr Marek; Yakovlev, Alexander B.; Arslanagic, Samel

2016-01-01

We investigate the ability of surface impedance mantle cloaks for cloaking of elliptical cylinders excited by an electric line source. The exact analytical solution of the problem utilizing Mathieu functions is obtained and is used to derive optimal surface impedances to cloak a number of configu......We investigate the ability of surface impedance mantle cloaks for cloaking of elliptical cylinders excited by an electric line source. The exact analytical solution of the problem utilizing Mathieu functions is obtained and is used to derive optimal surface impedances to cloak a number...

Artificial lateral-line system for imaging dipole sources using Beamforming techniques

NARCIS (Netherlands)

Dagamseh, A.M.K.; Wiegerink, Remco J.; Lammerink, Theodorus S.J.; Krijnen, Gijsbertus J.M.

In nature, fish have the ability to localize prey, school, navigate, etc. using the lateral-line organ [1]. Here we present the use of biomimetic artificial hair-based flow-sensors arranged as lateral-line system in combination with beamforming techniques for dipole source localization in air.

On-line spectral diagnostic system for Dalian Coherent Light Source

Energy Technology Data Exchange (ETDEWEB)

Li, Chaoyang; Wei, Shen; Du, Xuewei [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Du, Liangliang [National Synchrotron Radiation Laboratory, University of Science & Technology of China, Hefei, Anhui 230029 (China); Wang, Qiuping, E-mail: qiuping@ustc.edu.cn [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Zhang, Weiqing; Wu, Guorong; Dai, Dongxu [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Yang, Xueming, E-mail: xmyang@dicp.ac.cn [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

2015-05-21

The Dalian Coherent Light Source (DCLS) is a Free electron laser (FEL) user facility currently under construction in the northeast of China. It is designed to work on high gain high harmonic principle with the capability of wavelength continuously tunable in the EUV regime of 50–150 nm. The light source has unique features such as the turntable radiation frequency, wide spectral range, high brightness and peak power, very short pulse time structure, etc. A key diagnostic task in DCLS is the on-line source spectral characteristic recording during the source development, and for the definition of the experimental conditions. For this purpose, an online grazing incidence spectrometer with a toroidal mirror and a variable-line-spacing plane grating is designed and presented in this paper to monitor each single FEL pulse. A circular stage is chosen to fit the focal curve and to realize the wavelength scanning. This scanning mechanics is simpler and stable. Resolving power (λ/Δλ) of this spectrometer is better than 12,000 in the whole wavelength range.

On-line spectral diagnostic system for Dalian Coherent Light Source

International Nuclear Information System (INIS)

Li, Chaoyang; Wei, Shen; Du, Xuewei; Du, Liangliang; Wang, Qiuping; Zhang, Weiqing; Wu, Guorong; Dai, Dongxu; Yang, Xueming

2015-01-01

The Dalian Coherent Light Source (DCLS) is a Free electron laser (FEL) user facility currently under construction in the northeast of China. It is designed to work on high gain high harmonic principle with the capability of wavelength continuously tunable in the EUV regime of 50–150 nm. The light source has unique features such as the turntable radiation frequency, wide spectral range, high brightness and peak power, very short pulse time structure, etc. A key diagnostic task in DCLS is the on-line source spectral characteristic recording during the source development, and for the definition of the experimental conditions. For this purpose, an online grazing incidence spectrometer with a toroidal mirror and a variable-line-spacing plane grating is designed and presented in this paper to monitor each single FEL pulse. A circular stage is chosen to fit the focal curve and to realize the wavelength scanning. This scanning mechanics is simpler and stable. Resolving power (λ/Δλ) of this spectrometer is better than 12,000 in the whole wavelength range

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Directory of Open Access Journals (Sweden)

Mauro Vestena

Full Text Available Abstract Whiskers have been used as a nanomaterial dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents.

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Energy Technology Data Exchange (ETDEWEB)

Vestena, Mauro; Gross, Idejan Padilha; Pires, Alfredo Tiburcio Nunes; Muller, Carmen Maria Olivera, E-mail: mauro@utfpr.edu.br [Universidade Federal Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2016-10-15

Whiskers have been used as a nano material dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents. (author)

Heterodyne detection using spectral line pairing for spectral phase encoding optical code division multiple access and dynamic dispersion compensation.

Science.gov (United States)

Yang, Yi; Foster, Mark; Khurgin, Jacob B; Cooper, A Brinton

2012-07-30

A novel coherent optical code-division multiple access (OCDMA) scheme is proposed that uses spectral line pairing to generate signals suitable for heterodyne decoding. Both signal and local reference are transmitted via a single optical fiber and a simple balanced receiver performs sourceless heterodyne detection, canceling speckle noise and multiple-access interference (MAI). To validate the idea, a 16 user fully loaded phase encoded system is simulated. Effects of fiber dispersion on system performance are studied as well. Both second and third order dispersion management is achieved by using a spectral phase encoder to adjust phase shifts of spectral components at the optical network unit (ONU).

X-ray intensity and source size characterizations for the 25 kV upgraded Manson source at Sandia National Laboratories

Energy Technology Data Exchange (ETDEWEB)

Loisel, G., E-mail: gploise@sandia.gov; Lake, P.; Gard, P.; Dunham, G.; Nielsen-Weber, L.; Wu, M. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Norris, E. [Missouri University of Science and Technology, Rolla, Missouri 65409 (United States)

2016-11-15

At Sandia National Laboratories, the x-ray generator Manson source model 5 was upgraded from 10 to 25 kV. The purpose of the upgrade is to drive higher characteristics photon energies with higher throughput. In this work we present characterization studies for the source size and the x-ray intensity when varying the source voltage for a series of K-, L-, and M-shell lines emitted from Al, Y, and Au elements composing the anode. We used a 2-pinhole camera to measure the source size and an energy dispersive detector to monitor the spectral content and intensity of the x-ray source. As the voltage increases, the source size is significantly reduced and line intensity is increased for the three materials. We can take advantage of the smaller source size and higher source throughput to effectively calibrate the suite of Z Pulsed Power Facility crystal spectrometers.

X-ray intensity and source size characterizations for the 25 kV upgraded Manson source at Sandia National Laboratories.

Science.gov (United States)

Loisel, G; Lake, P; Gard, P; Dunham, G; Nielsen-Weber, L; Wu, M; Norris, E

2016-11-01

At Sandia National Laboratories, the x-ray generator Manson source model 5 was upgraded from 10 to 25 kV. The purpose of the upgrade is to drive higher characteristics photon energies with higher throughput. In this work we present characterization studies for the source size and the x-ray intensity when varying the source voltage for a series of K-, L-, and M-shell lines emitted from Al, Y, and Au elements composing the anode. We used a 2-pinhole camera to measure the source size and an energy dispersive detector to monitor the spectral content and intensity of the x-ray source. As the voltage increases, the source size is significantly reduced and line intensity is increased for the three materials. We can take advantage of the smaller source size and higher source throughput to effectively calibrate the suite of Z Pulsed Power Facility crystal spectrometers.

Radiating nonuniform transmission-line systems and the partial element equivalent circuit method

CERN Document Server

Nitsch, Juergen; Wollenberg, Gunter

2009-01-01

High frequencies of densely packed modern electronic equipment turn even the smallest piece of wire into a transmission line with signal retardation, dispersion, attenuation, and distortion. In electromagnetic environments with high-power microwave or ultra-wideband sources, transmission lines pick up noise currents generated by external electromagnetic fields. These are superimposed on essential signals, the lines acting not only as receiving antennas but radiating parts of the signal energy into the environment. This book is outstanding in its originality. While many textbooks rephrase

Cluster observations of ion dispersion discontinuities in the polar cusp

Science.gov (United States)

Escoubet, C. P.; Berchem, J.; Pitout, F.; Richard, R. L.; Trattner, K. J.; Grison, B.; Taylor, M. G.; Masson, A.; Dunlop, M. W.; Dandouras, I. S.; Reme, H.; Fazakerley, A. N.

2009-12-01

The reconnection between the interplanetary magnetic field (IMF) and the Earth’s magnetic field is taking place at the magnetopause on magnetic field lines threading through the polar cusp. When the IMF is southward, reconnection occurs near the subsolar point, which is magnetically connected to the equatorward boundary of the polar cusp. Subsequently the ions injected through the reconnection point precipitate in the cusp and are dispersed poleward. If reconnection is continuous and operates at constant rate, the ion dispersion is smooth and continuous. On the other hand if the reconnection rate varies, we expect interruption in the dispersion forming energy steps or staircase. Similarly, multiple entries near the magnetopause could also produce steps at low or mid-altitude when a spacecraft is crossing subsequently the field lines originating from these multiple sources. In addition, motion of the magnetopause induced by solar wind pressure changes or erosion due to reconnection can also induce a motion of the polar cusp and a disruption of the ions dispersion observed by a spacecraft. Cluster with four spacecraft following each other in the mid-altitude cusp can be used to distinguish between these “temporal” and “spatial” effects. We will present a cusp crossing with two spacecraft, separated by around two minutes. The two spacecraft observed a very similar dispersion with a step in energy in its centre and two other dispersions poleward. We will show that the steps could be temporal (assuming that the time between two reconnection bursts corresponds to the time delay between the two spacecraft) but it would be a fortuitous coincidence. On the other hand the steps and the two poleward dispersions could be explained by spatial effects if we take into account the motion of the open-closed boundary between the two spacecraft crossings.

The extinction to the H2 line emission in the DR 21 outflow source

International Nuclear Information System (INIS)

Nadeau, D.; Riopel, M.; Geballe, T.R.

1991-01-01

The v = 1-0 S(1) and Q(3) lines of H2 have been measured in four regions of the DR 21 H2 line-emission source, in order to determine whether the observed morphology of the emission represents the distribution of the excited H2 or is modified by nonuniform extinction across the source. The measured lines originate from the same upper level, and their ratio is a direct measure of the reddening. The line ratios show that the extinction is quite uniform across the source and that there is no correlation between the intensity and the extinction. This result implies that the gap between the two lobes of emission is not due to increased extinction but rather is a region where there is little excited H2 gas. 13 refs

ENDIX. A computer program to simulate energy dispersive X-ray and synchrotron powder diffraction diagrams

International Nuclear Information System (INIS)

Hovestreydt, E.; Karlsruhe Univ.; Parthe, E.; Benedict, U.

1987-01-01

A Fortran 77 computer program is described which allows the simulation of energy dispersive X-ray and synchrotron powder diffraction diagrams. The input consists of structural data (space group, unit cell dimensions, atomic positional and displacement parameters) and information on the experimental conditions (chosen Bragg angle, type of X-ray tube and applied voltage or operating power of synchrotron radiation source). The output consists of the normalized intensities of the diffraction lines, listed by increasing energy (in keV), and of an optional intensity-energy plot. The intensities are calculated with due consideration of the wave-length dependence of both the anomalous dispersion and the absorption coefficients. For a better agreement between observed and calculated spectra provision is made to optionally superimpose, on the calculated diffraction line spectrum, all additional lines such as fluorescence and emission lines and escape peaks. The different effects which have been considered in the simulation are discussed in some detail. A sample calculation of the energy dispersive powder diffraction pattern of UPt 3 (Ni 3 Sn structure type) is given. Warning: the user of ENDIX should be aware that for a successful application it is necessary to adapt the program to correspond to the actual experimental conditions. Even then, due to the only approximately known values of certain functions, the agreement between observed and calculated intensities will not be as good as for angle dispersive diffraction methods

Influence of source batch S{sub K} dispersion on dosimetry for prostate cancer treatment with permanent implants

Energy Technology Data Exchange (ETDEWEB)

Nuñez-Cumplido, E., E-mail: ejnc-mccg@hotmail.com; Hernandez-Armas, J. [Medical Physics Department, University Hospital of the Canary Island, La Cuesta – Ofra, 38003 La Laguna (Spain); Perez-Calatayud, J. [Radiotherapy Department, La Fe University Hospital, Bulevar Sur, 46026 Valencia (Spain); Casares-Magaz, O. [Medical Physics Department, University Hospital of the Canary Island, La Cuesta – Ofra, 38003 La Laguna, Spain and Medical Physics Department, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus (Denmark)

2015-08-15

Purpose: In clinical practice, specific air kerma strength (S{sub K}) value is used in treatment planning system (TPS) permanent brachytherapy implant calculations with {sup 125}I and {sup 103}Pd sources; in fact, commercial TPS provide only one S{sub K} input value for all implanted sources and the certified shipment average is typically used. However, the value for S{sub K} is dispersed: this dispersion is not only due to the manufacturing process and variation between different source batches but also due to the classification of sources into different classes according to their S{sub K} values. The purpose of this work is to examine the impact of S{sub K} dispersion on typical implant parameters that are used to evaluate the dose volume histogram (DVH) for both planning target volume (PTV) and organs at risk (OARs). Methods: The authors have developed a new algorithm to compute dose distributions with different S{sub K} values for each source. Three different prostate volumes (20, 30, and 40 cm{sup 3}) were considered and two typical commercial sources of different radionuclides were used. Using a conventional TPS, clinically accepted calculations were made for {sup 125}I sources; for the palladium, typical implants were simulated. To assess the many different possible S{sub K} values for each source belonging to a class, the authors assigned an S{sub K} value to each source in a randomized process 1000 times for each source and volume. All the dose distributions generated for each set of simulations were assessed through the DVH distributions comparing with dose distributions obtained using a uniform S{sub K} value for all the implanted sources. The authors analyzed several dose coverage (V{sub 100} and D{sub 90}) and overdosage parameters for prostate and PTV and also the limiting and overdosage parameters for OARs, urethra and rectum. Results: The parameters analyzed followed a Gaussian distribution for the entire set of computed dosimetries. PTV and

Transitional free convection flows induced by thermal line sources

NARCIS (Netherlands)

Bastiaans, R.J.M.

1993-01-01

In the present study the usefullness of a large eddy simulation for transition is examined. Numerical results of such simulations are presented from a study to determine the characteristics of a flow induced by a thermal line source. The first bifurcation to time dependent motion and the route to

Metasurface Cloak Performance Near-by Multiple Line Sources and PEC Cylindrical Objects

DEFF Research Database (Denmark)

Arslanagic, Samel; Yatman, William H.; Pehrson, Signe

2014-01-01

The performance/robustness of metasurface cloaks to a complex field environment which may represent a realistic scenario of radiating sources is presently reported. Attention is devoted to the cloak operation near-by multiple line sources and multiple perfectly electrically conducting cylinders. ...

Characterization of air pollutant concentrations, fleet emission factors, and dispersion near a North Carolina interstate freeway across two seasons

Science.gov (United States)

Saha, Provat K.; Khlystov, Andrey; Snyder, Michelle G.; Grieshop, Andrew P.

2018-03-01

We present field measurement data and modeling of multiple traffic-related air pollutants during two seasons at a site adjoining Interstate 40, near Durham, North Carolina. We analyze spatial-temporal and seasonal trends and fleet-average pollutant emission factors and use our data to evaluate a line source dispersion model. Month-long measurement campaigns were performed in summer 2015 and winter 2016. Data were collected at a fixed near-road site located within 10 m from the highway edge, an upwind background site and, under favorable meteorological conditions, along downwind perpendicular transects. Measurements included the size distribution, chemical composition, and volatility of submicron particles, black carbon (BC), nitrogen oxides (NOx), meteorological conditions and traffic activity data. Results show strong seasonal and diurnal differences in spatial distribution of traffic sourced pollutants. A strong signature of vehicle emissions was observed within 100-150 m from the highway edge with significantly higher concentrations during morning. Substantially higher concentrations and less-sharp near-road gradients were observed in winter for many species. Season-specific fleet-average fuel-based emission factors for NO, NOx, BC, and particle number (PN) were derived based on up- and down-wind roadside measurements. The campaign-average NOx and PN emission factors were 20% and 300% higher in winter than summer, respectively. These results suggest that the combined effect of higher emissions and their slower downwind dispersion in winter dictate the observed higher downwind concentrations and wider highway influence zone in winter for several species. Finally, measurements of traffic data, emission factors, and pollutant concentrations were integrated to evaluate a line source dispersion model (R-LINE). The dispersion model captured the general trends in the spatial and temporal patterns in near-road concentrations. However, there was a tendency for the model

Impact assessment of radionuclide dispersion due to stuck of sources used in well logging

International Nuclear Information System (INIS)

Amado, V. A.; Alvarez, D.E.; Lee Gonzáles, H.

2015-01-01

The well logging allows to characterize and to predict the hydrocarbon potential of an area. For this, tools that may contain one or more radioactive sources are used. Eventually, they may be stuck at a certain depth, without viable technical alternatives for recovery. In this case, it is necessary to implement actions that minimize the risk of release of radioactive material into the groundwater, because of the natural degradation of shielding or by the accidental destruction by the unexpected collision with another tool, in a possible future drilling. In this paper, a simplified assessment of the doses associated with the natural degradation and the breakdown of shielding radioactive sources is presented. For this purpose two main pathways of exposure; incorporation by ingestion of contaminated water from the aquifer and external irradiation because of the drilling mud that rise to the surface and distributed over it, are considered. Each of these pathways corresponds to a different scenario. In the first scenario, the evaluation was performed by applying the Dispersion of Radionuclides in Aquifers model that take in account pollutants dispersion in the aquifer unto extraction well water. This model solves the equation of solute transport in porous media in three dimensions, considering soil retention and radioactive decay. In the second scenario the contaminated mud rises from the well to the surface, due to actions taken to retrieve stuck sources or because of new drillings are assumed. The aim of this work is to present a simple and conservative method to estimate doses involved in the natural degradation of shielding or by accidental destruction of sources used in well logging. (authors) [es

Dispersed Fringe Sensing Analysis - DFSA

Science.gov (United States)

Sigrist, Norbert; Shi, Fang; Redding, David C.; Basinger, Scott A.; Ohara, Catherine M.; Seo, Byoung-Joon; Bikkannavar, Siddarayappa A.; Spechler, Joshua A.

2012-01-01

Dispersed Fringe Sensing (DFS) is a technique for measuring and phasing segmented telescope mirrors using a dispersed broadband light image. DFS is capable of breaking the monochromatic light ambiguity, measuring absolute piston errors between segments of large segmented primary mirrors to tens of nanometers accuracy over a range of 100 micrometers or more. The DFSA software tool analyzes DFS images to extract DFS encoded segment piston errors, which can be used to measure piston distances between primary mirror segments of ground and space telescopes. This information is necessary to control mirror segments to establish a smooth, continuous primary figure needed to achieve high optical quality. The DFSA tool is versatile, allowing precise piston measurements from a variety of different optical configurations. DFSA technology may be used for measuring wavefront pistons from sub-apertures defined by adjacent segments (such as Keck Telescope), or from separated sub-apertures used for testing large optical systems (such as sub-aperture wavefront testing for large primary mirrors using auto-collimating flats). An experimental demonstration of the coarse-phasing technology with verification of DFSA was performed at the Keck Telescope. DFSA includes image processing, wavelength and source spectral calibration, fringe extraction line determination, dispersed fringe analysis, and wavefront piston sign determination. The code is robust against internal optical system aberrations and against spectral variations of the source. In addition to the DFSA tool, the software package contains a simple but sophisticated MATLAB model to generate dispersed fringe images of optical system configurations in order to quickly estimate the coarse phasing performance given the optical and operational design requirements. Combining MATLAB (a high-level language and interactive environment developed by MathWorks), MACOS (JPL s software package for Modeling and Analysis for Controlled Optical

An atmospheric dispersion model for linear sources in calm wind, stable conditions; Un modello di dispersione atmosferica per sorgenti lineari in condizioni di vento debole

Energy Technology Data Exchange (ETDEWEB)

Cirillo, M. C. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente; Buratti, D. [Rome Univ. La Sapienza, Rome (Italy). Facolta' di Scienze Statistiche; Metallo, M. C.; Poli, A.A. [ESA s.a.s., Bracciano, RM (Italy)

1999-07-01

In this report a dispersion model is proposed that provides an estimate of concentration of gaseous pollutants emitted by an highway, or in general by a line source, in presence of low wind speed. This aim was pursued because available models have not a satisfactory behaviour in such conditions, which is critical for dispersion of gaseous pollutants. This lack is due to difficulty of simulating dispersion turbulent component which is determined by fluctuation of wind speed and wind direction, and in presence of calm conditions it assumes values comparable with transport component. The proposed model overcomes this difficulty, as it is shown by sensitivity analysis and comparison with experimental data. The capability of simulating dispersion eve in critical conditions, like the presence of low level inversion, and the absence of source geometrical approximations make the model a tool that, properly used, may contribute to the efficient planning and management of environmental resources. [Italian] In questo rapporto viene proposto un modello per la stima delle concentrazioni di inquinanti aeriformi emessi da un'arteria stradale, o in generale da una sorgente lineare, in presenza di vento debole. Questo scopo e' stato perseguito in quanto in questa condizione, nonostante la dispersione degli inquinanti risulti fortemente problematica, i modelli disponibili in letteratura non hanno un comportamento soddisfacente. Questa mancanca e' attribuibile alla difficolta' di simulare la componente turbolenta della dispersione, dovuta alla fluttuazione della direzione e della velocita' del vento che, in presenza di vento debole, assume valori confrontabili alla componente di trasporto. Il modello qui di seguito proposto supera questa difficolta', come dimostrano l'analisi di sensibilita' e il confronto con un caso reale; la capacita' di simulare la dispersione anche in condizioni fisicamente critiche quali la presenza di inversione a

Ion source development for the on-line isotope separator at GSI

International Nuclear Information System (INIS)

Kirchner, R.; Burkard, K.; Hueller, W.; Klepper, O.

1991-08-01

The progress in the understanding of ion sources for isotope separation on-line and the feasibility of bunched beams of relatively refractory elements is reported. The ultra-high temperature FEBIAD-H ion source, facilitating the mounting of catchers and window compared to the earlier F-version, enables bunched beams of the elements with adsorption enthalpies up to almost 6 eV, e.g. of Be, Al, Ca, Cr, Fe, Co, Ni, Sr, Pd, Ba, Yb, and Au. This way also chemical selectivity for these elements may be achieved, at least to some extent, for isotopes with halflives > or approx.1 minute, including especially the difficult separation of alkaline-earth isotopes from isobaric alkalines. These studies reveal, however, also a principal difficulty in the on-line separation of refractory elements, namely their tendency, increasing with ΔH a , to re-diffuse after release from the catcher into the bulk of the hot source enclosure. (orig.)

A new energy-dispersive powder diffraction facility at the SRS

International Nuclear Information System (INIS)

Clark, S.M.

1996-01-01

A new energy-dispersive powder diffraction facility has been constructed on the 6 T wiggler beam line of the Daresbury Laboratory Synchrotron Radiation Source. This paper describes the facility, in particular the beam definition apparatus (front end), the detector positioning system (back end), a 10 000 kN loading frame and high pressure cell and the counting and control electronics. Some recent results are presented including a study of the compressibility of talc and the phase I→II transition of ammonium chloride. (orig.)

Laser-plasma sourced, temperature dependent, VUV spectrophotometer using dispersive analysis

International Nuclear Information System (INIS)

French, R.H.

1990-01-01

We have developed a vacuum ultraviolet spectrophotometer with wide energy and temperature range coverage, utilizing a laser-plasma light source (LPLS), CO 2 -laser sample heating and time-resolved dispersive analysis. Reflection and transmission spectra can be taken from 1.7 to 40 eV (31-700 nm) on samples at 15-1800 K with a time resolution of 20-400 ns. These capabilities permit the study of the temperature dependence of the electronic structure, encompassing the effects of thermal lattice expansion and electron-phonon interaction, and changes in the electronic structure associated with equilibrium and metastable phase transitions and stress relaxation. The LPLS utilizes a samarium laser-plasma created by a Q-switched Nd:YAG laser (500 mJ/pulse) to produce high brightness, stable, continuum radiation. The spectrophotometer is of a single beam design using calibrated iridium reference mirrors. White light is imaged off the sample in to the entrance slit of a 1-m polychromator. The resolution is 0.1 to 0.3 nm. The dispersed light is incident on a focal plane phosphor, fiber-optic-coupled to an image-intensified reticon detector. For spectroscopy between 300 and 1800 K, the samples are heated in situ with a 150 Watt CO 2 laser. The signal to noise ratio in the VUV, for samples at 1800 K, is excellent. From 300 K to 15 K samples are cooled using a He cryostat. (orig.)

On-line measurement of microwave power in ECR ion source

International Nuclear Information System (INIS)

Zhou Changgeng; Kang Wu; Hu Yonghong; Li Yan; Lou Benchao; Zu Xiulan; Xiong Riheng; Chen Junguang; Li Xiaoyun

2005-01-01

It is a new technology to apply an ECR ion source to the neutron generator. Because of the structure limitation, working state of the ECR ion source could not be judged by the color of gas discharging in discharge chamber. Therefore, it was hard to estimate if the ECR ion source was working properly in the neutron generator. The method to resolve the problem was described in this paper. The microwave power was measured on-line by a directional coupler and a small microwave power meter. The ion beam current could be educed from the measured incidence microwave power, and discharge state in discharge chamber could be determined. (authors)

Nozzle for electric dispersion reactor

Science.gov (United States)

Sisson, W.G.; Basaran, O.A.; Harris, M.T.

1995-11-07

A nozzle for an electric dispersion reactor includes two concentric electrodes, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 4 figs.

Preferred orientation determination using line source x-ray diffraction

International Nuclear Information System (INIS)

Kimmel, G.; Shmarjahu, D.

1977-10-01

A texture goniometer has been attached to a diffractometer connected to a line-focus x-ray source. Reasonable results are obtained for the texture of rolled sheets and the test procedure is given. To illustrate the test procedure, the determination of preferred orientation in cold-rolled copper is described, as compared with random powder of sintered copper. Improvements of the measurements are proposed

Advanced photon source low-energy undulator test line

International Nuclear Information System (INIS)

Milton, S.V.

1997-01-01

The injector system of the Advanced Photon Source (APS) consists of a linac capable of producing 450-MeV positrons or > 650-MeV electrons, a positron accumulator ring (PAR), and a booster synchrotron designed to accelerate particles to 7 GeV. There are long periods of time when these machines are not required for filling the main storage ring and instead can be used for synchrotron radiation research. We describe here an extension of the linac beam transport called the Low-Energy Undulator Test Line (LEUTL). The LEUTL will have a twofold purpose. The first is to fully characterize innovative, future generation undulators, some of which may prove difficult or impossible to measure by traditional techniques. These might include small-gap and superconducting undulators, very long undulators, undulators with designed-in internal focusing, and helical undulators. This technique also holds the promise of extending the magnetic measurement sensitivity beyond that presently attainable. This line will provide the capability to directly test undulators before their possible insertion into operating storage rings. A second use for the test line will be to investigate the generation of coherent radiation at wavelengths down to a few tens of nanometers

High-concentration graphene dispersion stabilized by block copolymers in ethanol.

Science.gov (United States)

Perumal, Suguna; Lee, Hyang Moo; Cheong, In Woo

2017-07-01

This article describes a comprehensive study for the preparation of graphene dispersions by liquid-phase exfoliation using amphiphilic diblock copolymers; poly(ethylene oxide)-block-poly(styrene) (PEO-b-PS), poly(ethylene oxide)-block-poly(4-vinylpyridine) (PEO-b-PVP), and poly(ethylene oxide)-block-poly(pyrenemethyl methacrylate) (PEO-b-PPy) with similar block lengths. Block copolymers were prepared from PEO using the Steglich coupling reaction followed by reversible addition-fragmentation chain transfer (RAFT) polymerization. Graphite platelets (G) and reduced graphene oxide (rGO) were used as graphene sources. The dispersion stability of graphene in ethanol was comparatively investigated by on-line turbidity, and the graphene concentration in the dispersions was determined gravimetrically. Our results revealed that the graphene dispersions with PEO-b-PVP were much more stable and included graphene with fewer defects than that with PEO-b-PS or PEO-b-PPy, as confirmed by turbidity and Raman analyses. Gravimetry confirmed that graphene concentrations up to 1.7 and 1.8mg/mL could be obtained from G and rGO dispersions, respectively, using PEO-b-PVP after one week. Distinctions in adhesion forces of PS, VP, PPy block units with graphene surface and the variation in solubility of the block copolymers in ethanol medium significantly affected the stability of the graphene dispersion. Copyright © 2017 Elsevier Inc. All rights reserved.

Seed dispersal into wetlands: Techniques and results for a restored tidal freshwater marsh

Science.gov (United States)

Neff, K.P.; Baldwin, A.H.

2005-01-01

Although seed dispersal is assumed to be a major factor determining plant community development in restored wetlands, little research exists on density and species richness of seed available through dispersal in these systems. We measured composition and seed dispersal rates at a restored tidal freshwater marsh in Washington, DC, USA by collecting seed dispersing through water and wind. Seed dispersal by water was measured using two methods of seed collection: (1) stationary traps composed of coconut fiber mat along an elevation gradient bracketing the tidal range and (2) a floating surface trawl net attached to a boat. To estimate wind dispersal rates, we collected seed from stationary traps composed of coconut fiber mat positioned above marsh vegetation. We also collected a small number of samples of debris deposited along high tide lines (drift lines) and feces of Canada Goose to explore their seed content. We used the seedling emergence method to determine seed density in all samples, which involved placing the fiber mats or sample material on top of potting soil in a greenhouse misting room and enumerating emerging seedlings. Seedlings from a total of 125 plant species emerged during this study (including 82 in river trawls, 89 in stationary water traps, 21 in drift lines, 39 in wind traps, and 10 in goose feces). The most abundant taxa included Bidens frondosa, Boehmeria cylindrica, Cyperus spp., Eclipta prostrata, and Ludwigia palustris. Total seedling density was significantly greater for the stationary water traps (212 + 30.6 seeds/m2/month) than the equal-sized stationary wind traps (18 + 6.0 seeds/m(2)/month). Lower-bound estimates of total species richness based on the non-parametric Chao 2 asymptotic estimators were greater for seeds in water (106 + 1.4 for stationary water traps and 104 + 5.5 for trawl samples) than for wind (54 + 6.4). Our results indicate that water is the primary source of seeds dispersing to the site and that a species-rich pool

RANS modeling of scalar dispersion from localized sources within a simplified urban-area model

Science.gov (United States)

Rossi, Riccardo; Capra, Stefano; Iaccarino, Gianluca

2011-11-01

The dispersion of a passive scalar downstream a localized source within a simplified urban-like geometry is examined by means of RANS scalar flux models. The computations are conducted under conditions of neutral stability and for three different incoming wind directions (0°, 45°, 90°) at a roughness Reynolds number of Ret = 391. A Reynolds stress transport model is used to close the flow governing equations whereas both the standard eddy-diffusivity closure and algebraic flux models are employed to close the transport equation for the passive scalar. The comparison with a DNS database shows improved reliability from algebraic scalar flux models towards predicting both the mean concentration and the plume structure. Since algebraic flux models do not increase substantially the computational effort, the results indicate that the use of tensorial-diffusivity can be promising tool for dispersion simulations for the urban environment.

Source-receptor matrix calculation with a Lagrangian particle dispersion model in backward mode

Directory of Open Access Journals (Sweden)

P. Seibert

2004-01-01

Full Text Available The possibility to calculate linear-source receptor relationships for the transport of atmospheric trace substances with a Lagrangian particle dispersion model (LPDM running in backward mode is shown and presented with many tests and examples. This mode requires only minor modifications of the forward LPDM. The derivation includes the action of sources and of any first-order processes (transformation with prescribed rates, dry and wet deposition, radioactive decay, etc.. The backward mode is computationally advantageous if the number of receptors is less than the number of sources considered. The combination of an LPDM with the backward (adjoint methodology is especially attractive for the application to point measurements, which can be handled without artificial numerical diffusion. Practical hints are provided for source-receptor calculations with different settings, both in forward and backward mode. The equivalence of forward and backward calculations is shown in simple tests for release and sampling of particles, pure wet deposition, pure convective redistribution and realistic transport over a short distance. Furthermore, an application example explaining measurements of Cs-137 in Stockholm as transport from areas contaminated heavily in the Chernobyl disaster is included.

A GIS-based atmospheric dispersion model for pollutants emitted by complex source areas.

Science.gov (United States)

Teggi, Sergio; Costanzini, Sofia; Ghermandi, Grazia; Malagoli, Carlotta; Vinceti, Marco

2018-01-01

Gaussian dispersion models are widely used to simulate the concentrations and deposition fluxes of pollutants emitted by source areas. Very often, the calculation time limits the number of sources and receptors and the geometry of the sources must be simple and without holes. This paper presents CAREA, a new GIS-based Gaussian model for complex source areas. CAREA was coded in the Python language, and is largely based on a simplified formulation of the very popular and recognized AERMOD model. The model allows users to define in a GIS environment thousands of gridded or scattered receptors and thousands of complex sources with hundreds of vertices and holes. CAREA computes ground level, or near ground level, concentrations and dry deposition fluxes of pollutants. The input/output and the runs of the model can be completely managed in GIS environment (e.g. inside a GIS project). The paper presents the CAREA formulation and its applications to very complex test cases. The tests shows that the processing time are satisfactory and that the definition of sources and receptors and the output retrieval are quite easy in a GIS environment. CAREA and AERMOD are compared using simple and reproducible test cases. The comparison shows that CAREA satisfactorily reproduces AERMOD simulations and is considerably faster than AERMOD. Copyright © 2017 Elsevier B.V. All rights reserved.

Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

Energy Technology Data Exchange (ETDEWEB)

Al Razi, Khandakar Md Habib; Hiroshi, Moritomi; Shinji, Kambara [Environmental and Renewable Energy System (ERES), Graduate School of Engineering, Gifu University, Yanagido, Gifu City, 501-1193 (Japan)

2012-07-01

The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environmental concern. Identification of sources contributing to the high atmospheric mercury levels will be useful for formulating pollution control and mitigation strategies in the region. In Japan, mercury and its compounds were categorized as hazardous air pollutants in 1996 and are on the list of 'Substances Requiring Priority Action' published by the Central Environmental Council of Japan. The Air Quality Management Division of the Environmental Bureau, Ministry of the Environment, Japan, selected the current annual mean environmental air quality standard for mercury and its compounds of 0.04 ?g/m3. Long-term exposure to mercury and its compounds can have a carcinogenic effect, inducing eg, Minamata disease. This study evaluates the impact of mercury emissions on air quality in the coastal area of Japan. Average yearly emission of mercury from an elevated point source in this area with background concentration and one-year meteorological data were used to predict the ground level concentration of mercury. To estimate the concentration of mercury and its compounds in air of the local area, two different simulation models have been used. The first is the National Institute of Advanced Science and Technology Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER) that estimates regional atmospheric concentration and distribution. The second is the Hybrid Single Particle Lagrangian Integrated trajectory Model (HYSPLIT) that estimates the atmospheric

Mode-dependent dispersion in Raman line shapes: Observation and implications from ultrafast Raman loss spectroscopy

International Nuclear Information System (INIS)

Umapathy, S.; Mallick, B.; Lakshmanna, A.

2010-01-01

Ultrafast Raman loss spectroscopy (URLS) enables one to obtain the vibrational structural information of molecular systems including fluorescent materials. URLS, a nonlinear process analog to stimulated Raman gain, involves a narrow bandwidth picosecond Raman pump pulse and a femtosecond broadband white light continuum. Under nonresonant condition, the Raman response appears as a negative (loss) signal, whereas, on resonance with the electronic transition the line shape changes from a negative to a positive through a dispersive form. The intensities observed and thus, the Franck-Condon activity (coordinate dependent), are sensitive to the wavelength of the white light corresponding to a particular Raman frequency with respect to the Raman pump pulse wavelength, i.e., there is a mode-dependent response in URLS.

Radiation of planar electromagnetic waves by a line source in anisotropic metamaterials

International Nuclear Information System (INIS)

Cheng Qiang; Jiang Weixiang; Cui Tiejun

2010-01-01

We show experimentally that a line source in an anisotropic metamaterial directly radiates planar electromagnetic waves instead of cylindrical waves, when one component of the permeability tensor approaches zero. The impedance of this material can be perfectly matched to that of free space, which can significantly reduce the reflections between the source and the superstrate, as in traditional highly directive antennas based on zero index metamaterials. Such a unique property determines the two-way propagation of electromagnetic waves excited by a line source, instead of all-way propagation. From this feature, a highly directive emission of electromagnetic waves is achieved using the anisotropic metamaterial with arbitrary shape. We have designed and fabricated the anisotropic metamaterial in the microwave region, and observed the generation of plane waves and their highly directive emission. The proposed plane-wave emission is independent of the shape variance of the anisotropic metamaterial, which can be utilized in the design of conformal antennas.

Improved design of proton source and low energy beam transport line for European Spallation Source

Energy Technology Data Exchange (ETDEWEB)

Neri, L., E-mail: neri@lns.infn.it; Celona, L.; Gammino, S.; Mascali, D.; Castro, G.; Ciavola, G. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Torrisi, G. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile, Università Mediterranea di Reggio Calabria, Via Graziella, 89122 Reggio Calabria (Italy); Cheymol, B.; Ponton, A. [European Spallation Source ESS AB, Lund (Sweden); Galatà, A. [Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell' università 2, 35020 Legnaro (Italy); Patti, G. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell' università 2, 35020 Legnaro (Italy); Gozzo, A.; Lega, L. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Ingegneria Informatica e delle Telecomunicazioni, Università degli Studi di Catania, Viale Andrea Doria 6, 95123 Catania (Italy)

2014-02-15

The design update of the European Spallation Source (ESS) accelerator is almost complete and the construction of the prototype of the microwave discharge ion source able to provide a proton beam current larger than 70 mA to the 3.6 MeV Radio Frequency Quadrupole (RFQ) started. The source named PS-ESS (Proton Source for ESS) was designed with a flexible magnetic system and an extraction system able to merge conservative solutions with significant advances. The ESS injector has taken advantage of recent theoretical updates and new plasma diagnostics tools developed at INFN-LNS (Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare). The design strategy considers the PS-ESS and the low energy beam transport line as a whole, where the proton beam behaves like an almost neutralized non-thermalized plasma. Innovative solutions have been used as hereinafter described. Thermo-mechanical optimization has been performed to withstand the chopped beam and the misaligned focused beam over the RFQ input collimator; the results are reported here.

Bright broadband coherent fiber sources emitting strongly blue-shifted resonant dispersive wave pulses

DEFF Research Database (Denmark)

Tu, Haohua; Lægsgaard, Jesper; Zhang, Rui

2013-01-01

We predict and realize the targeted wavelength conversion from the 1550-nm band of a fs Er:fiber laser to an isolated band inside 370-850 nm, corresponding to a blue-shift of 700-1180 nm. The conversion utilizes resonant dispersive wave generation in widely available optical fibers with good...... efficiency (~7%). The converted band has a large pulse energy (~1 nJ), high spectral brightness (~1 mW/nm), and broad Gaussian-like spectrum compressible to clean transform-limited ~17 fs pulses. The corresponding coherent fiber sources open up portable applications of optical parametric oscillators and dual......-output synchronized ultrafast lasers....

A new approximation of the dispersion relations occurring in the sound-attenuation problem of turbofan aircraft engines

Directory of Open Access Journals (Sweden)

Robert SZABO

2011-12-01

Full Text Available The dispersion relations, appearing in the analysis of the stability of a gas flow in a straight acoustically-lined duct with respect to perturbations produced by a time harmonic source, beside the wave number and complex frequency contain the solution of a boundary value problem of the Pridmore-Brown equation depending on the wave number and frequency. For this reason, in practice the dispersion relations are rarely simple enough for carried out the zeros. The determination of zeros of these dispersion relations is crucial for the prediction of the perturbation attenuation or amplification. In this paper an approximation of the dispersion relations is given. Our approach preserves the general character of the mean flow, the general Pridmore-Brown equation and it’s only in the shear flow that we replace the exact solution of the boundary value problem with its Taylor polynomial approximate. In this way new approximate dispersion relations are obtained which zero’s can be found by computer.

STATCONT: A statistical continuum level determination method for line-rich sources

Science.gov (United States)

Sánchez-Monge, Á.; Schilke, P.; Ginsburg, A.; Cesaroni, R.; Schmiedeke, A.

2018-01-01

STATCONT is a python-based tool designed to determine the continuum emission level in spectral data, in particular for sources with a line-rich spectrum. The tool inspects the intensity distribution of a given spectrum and automatically determines the continuum level by using different statistical approaches. The different methods included in STATCONT are tested against synthetic data. We conclude that the sigma-clipping algorithm provides the most accurate continuum level determination, together with information on the uncertainty in its determination. This uncertainty can be used to correct the final continuum emission level, resulting in the here called `corrected sigma-clipping method' or c-SCM. The c-SCM has been tested against more than 750 different synthetic spectra reproducing typical conditions found towards astronomical sources. The continuum level is determined with a discrepancy of less than 1% in 50% of the cases, and less than 5% in 90% of the cases, provided at least 10% of the channels are line free. The main products of STATCONT are the continuum emission level, together with a conservative value of its uncertainty, and datacubes containing only spectral line emission, i.e., continuum-subtracted datacubes. STATCONT also includes the option to estimate the spectral index, when different files covering different frequency ranges are provided.

Industrial point source CO2 emission strength estimation with aircraft measurements and dispersion modelling.

Science.gov (United States)

Carotenuto, Federico; Gualtieri, Giovanni; Miglietta, Franco; Riccio, Angelo; Toscano, Piero; Wohlfahrt, Georg; Gioli, Beniamino

2018-02-22

CO 2 remains the greenhouse gas that contributes most to anthropogenic global warming, and the evaluation of its emissions is of major interest to both research and regulatory purposes. Emission inventories generally provide quite reliable estimates of CO 2 emissions. However, because of intrinsic uncertainties associated with these estimates, it is of great importance to validate emission inventories against independent estimates. This paper describes an integrated approach combining aircraft measurements and a puff dispersion modelling framework by considering a CO 2 industrial point source, located in Biganos, France. CO 2 density measurements were obtained by applying the mass balance method, while CO 2 emission estimates were derived by implementing the CALMET/CALPUFF model chain. For the latter, three meteorological initializations were used: (i) WRF-modelled outputs initialized by ECMWF reanalyses; (ii) WRF-modelled outputs initialized by CFSR reanalyses and (iii) local in situ observations. Governmental inventorial data were used as reference for all applications. The strengths and weaknesses of the different approaches and how they affect emission estimation uncertainty were investigated. The mass balance based on aircraft measurements was quite succesful in capturing the point source emission strength (at worst with a 16% bias), while the accuracy of the dispersion modelling, markedly when using ECMWF initialization through the WRF model, was only slightly lower (estimation with an 18% bias). The analysis will help in highlighting some methodological best practices that can be used as guidelines for future experiments.

Radiation source states on-line supervision system design and implementation based on RFID technology

International Nuclear Information System (INIS)

Yang Binhua; Ling Qiu; Yin Guoli; Yang Kun; Wan Xueping; Wang Kan

2011-01-01

It puts forward radiation source states on-line monitoring resolution based on RFID technology. Firstly, the system uses RFID in real-time transmission of the radiation dose rate, and monitors the radiation source states and dose rate of the surrounding environment on-line. Then it adopts regional wireless networking mode to construct enterprise level monitoring network, which resolves long-distance wiring problems. And then it uses GPRS wireless to transport the real-time data to the monitoring center and the government supervision department, By adopting randomly dynamic cording in display update every day, it strengthens the supervision of the radiation source. At last this system has been successful applied to a thickness gauge project, which verifies the feasibility and practicality is good. (authors)

Investigation of gas discharge ion sources for on-line mass separation

International Nuclear Information System (INIS)

Kirchner, R.

1976-03-01

The development of efficient gas discharge ion sources with axial beam extraction for on-line mass separation is described. The aim of the investigation was to increase the ion source temperature, the lifetime and the ionisation yield in comparison to present low-pressure are discharge ion sources and to reduce the ion current density from usually 1 to 100 mA/cm 3 . In all ion sources the pressure range below the minimal ignition pressure of the arc discharge was investigated. As a result an ion source was developed which works at small changes in geometry and in electric device of a Nielsen source with high ionization yield (up to 50% for xenon) stabil and without ignition difficulties up to 10 -5 Torr. At a typical pressure of 3 x 10 -5 Torr ion current and ion current density are about 1 μA and 0.1 mA/cm 3 respectively besides high yield and a great emission aperture (diameter 1.2 mm). (orig.) [de

Nomogram for Determining Shield Thickness for Point and Line Sources of Gamma Rays

Energy Technology Data Exchange (ETDEWEB)

Joenemalm, C; Malen, K

1966-10-15

A set of nomograms is given for the determination of the required shield thickness against gamma radiation. The sources handled are point and infinite line sources with shields of Pb, Fe, magnetite concrete (p = 3.6), ordinary concrete (p = 2.3) or water. The gamma energy range covered is 0.5 - 10 MeV. The nomograms are directly applicable for source and dose points on the surfaces of the shield. They can easily be extended to source and dose points in other positions by applying a geometrical correction. Also included are data for calculation of the source strength for the most common materials and for fission product sources.

Nomogram for Determining Shield Thickness for Point and Line Sources of Gamma Rays

International Nuclear Information System (INIS)

Joenemalm, C.; Malen, K

1966-10-01

A set of nomograms is given for the determination of the required shield thickness against gamma radiation. The sources handled are point and infinite line sources with shields of Pb, Fe, magnetite concrete (p = 3.6), ordinary concrete (p = 2.3) or water. The gamma energy range covered is 0.5 - 10 MeV. The nomograms are directly applicable for source and dose points on the surfaces of the shield. They can easily be extended to source and dose points in other positions by applying a geometrical correction. Also included are data for calculation of the source strength for the most common materials and for fission product sources

Soft-to-hard templating to well-dispersed N-doped mesoporous carbon nanospheres via one-pot carbon/silica source copolymerization

Institute of Scientific and Technical Information of China (English)

Qinglu Kong; Lingxia Zhang; Min Wang; Mengli Li; Heliang Yao; Jianlin Shi

2016-01-01

Here we report a new approach referred as "softto-hard templating" strategy via the copolymerization of carbon source (dopamine) and silica source (tetraethyl orthosilicate) for the synthesis of well dispersed N-doped mesoporous carbon nanospheres (MCNs),which exhibit high performance for electrochemical supercapacitor.This method overcomes the shortcoming of uncontrolled dispersity and complicated procedures of soft-or hard-tem-plating methods,respectively.Moreover,the synthesized MCNs feature enriched heteroatom N-doping and easy functionalization by noble-metal nanoparticles during the one-pot synthesis.All the above characters make the asprepared MCNs a promising platform in a variety of applications.To demonstrate the applicability of the synthesized nitrogen-doped MCNs,this material has been employed as an electrode for high-performance electrochemical supercapacitor,which shows a capacitance of 223 and 140 F/g at current densities of 0.5 and 10 A/g in 1 mol/L KOH electrolyte,respectively.

Accident consequence assessments with different atmospheric dispersion models

International Nuclear Information System (INIS)

Panitz, H.J.

1989-11-01

An essential aim of the improvements of the new program system UFOMOD for Accident Consequence Assessments (ACAs) was to substitute the straight-line Gaussian plume model conventionally used in ACA models by more realistic atmospheric dispersion models. To identify improved models which can be applied in ACA codes and to quantify the implications of different dispersion models on the results of an ACA, probabilistic comparative calculations with different atmospheric dispersion models have been performed. The study showed that there are trajectory models available which can be applied in ACAs and that they provide more realistic results of ACAs than straight-line Gaussian models. This led to a completely novel concept of atmospheric dispersion modelling in which two different distance ranges of validity are distinguished: the near range of some ten kilometres distance and the adjacent far range which are assigned to respective trajectory models. (orig.) [de

Analytic Approximation to Radiation Fields from Line Source Geometry

International Nuclear Information System (INIS)

Michieli, I.

2000-01-01

Line sources with slab shields represent typical source-shield configuration in gamma-ray attenuation problems. Such shielding problems often lead to the generalized Secant integrals of the specific form. Besides numerical integration approach, various expansions and rational approximations with limited applicability are in use for computing the value of such integral functions. Lately, the author developed rapidly convergent infinite series representation of generalized Secant Integrals involving incomplete Gamma functions. Validity of such representation was established for zero and positive values of integral parameter a (a=0). In this paper recurrence relations for generalized Secant Integrals are derived allowing us simple approximate analytic calculation of the integral for arbitrary a values. It is demonstrated how truncated series representation can be used, as the basis for such calculations, when possibly negative a values are encountered. (author)

Evaluation of Bamboo Porous Pipe as Line Source Emitter in Trickle ...

African Journals Online (AJOL)

This paper attempts to evaluate the use of bamboo as porous pipe (line source) emitter in trickle irrigation at the Cross River University of Technology Teaching and Research Farm Obubra. Two sets of bamboo laterals: opened and plugged ends were used for the trial. The experiment was conducted using four different ...

evaluation of bamboo porous pipe as line source emitter in trickle ...

African Journals Online (AJOL)

CHRISTY

This paper attempts to evaluate the use of bamboo as porous pipe (line source) emitter in trickle irrigation at the Cross River University of Technology Teaching and Research Farm Obubra. Two sets of bamboo laterals: opened and plugged ends were used for the trial. The experiment was conducted using four different ...

Trees in urban street canyons and their impact on the dispersion of automobile exhausts

OpenAIRE

Gromke, Christof; Ruck, Bodo

2007-01-01

The aim of the present study is to clarify the influence of trees on the dispersion of automobile exhausts in urban street canyons. For this purpose, measurements have been performed with a small scale wind tunnel model of an idealized, isolated street canyon with model trees placed along the canyon center axis. Sulfur hexafluoride (SF6) was released from a line source embedded in the street surface, simulating vehicle exhaust emissions. The influence of various tree planting arrangements on ...

An Orbit And Dispersion Correction Scheme for the PEP II

International Nuclear Information System (INIS)

Cai, Y.; Donald, M.; Shoaee, H.; White, G.; Yasukawa, L.A.

2011-01-01

To achieve optimum luminosity in a storage ring it is vital to control the residual vertical dispersion. In the original PEP storage ring, a scheme to control the residual dispersion function was implemented using the ring orbit as the controlling element. The 'best' orbit not necessarily giving the lowest vertical dispersion. A similar scheme has been implemented in both the on-line control code and in the simulation code LEGO. The method involves finding the response matrices (sensitivity of orbit/dispersion at each Beam-Position-Monitor (BPM) to each orbit corrector) and solving in a least squares sense for minimum orbit, dispersion function or both. The optimum solution is usually a subset of the full least squares solution. A scheme of simultaneously correcting the orbits and dispersion has been implemented in the simulation code and on-line control system for PEP-II. The scheme is based on the eigenvector decomposition method. An important ingredient of the scheme is to choose the optimum eigenvectors that minimize the orbit, dispersion and corrector strength. Simulations indicate this to be a very effective way to control the vertical residual dispersion.

Novel plasma source for safe beryllium spectral line studies in the presence of beryllium dust

Science.gov (United States)

Stankov, B. D.; Vinić, M.; Gavrilović Božović, M. R.; Ivković, M.

2018-05-01

Plasma source for beryllium spectral line studies in the presence of beryllium dust particles was realised. The guideline during construction was to prevent exposure to formed dust, considering the toxicity of beryllium. Plasma source characterization through determination of optimal working conditions is described. The necessary conditions for Be spectral line appearance and optimal conditions for line shape measurements are found. It is proven experimentally that under these conditions dust appears coincidently with the second current maximum. The electron density measured after discharge current maximum is determined from the peak separation of the hydrogen Balmer beta spectral line, and the electron temperature is determined from the ratios of the relative intensities of Be spectral lines emitted from successive ionized stages of atoms. Maximum values of electron density and temperature are measured to be 9.3 × 1022 m-3 and 16 800 K, respectively. Construction details and testing of the BeO discharge tube in comparison with SiO2 and Al2O3 discharge tubes are also presented in this paper.

Dispersal of spores following a persistent random walk.

Science.gov (United States)

Bicout, D J; Sache, I

2003-03-01

A model of a persistent random walk is used to describe the transport and deposition of the spore dispersal process. In this model, the spore particle flies along straight line trajectories, with constant speed v, which are interrupted by scattering, originating from interaction of spores with the field and wind variations, which randomly change its direction. To characterize the spore dispersal gradients, we have derived analytical expressions of the deposition probability epsilon (r|v) of airborne spores as a function of the distance r from the spore source in an infinite free space and in a disk of radius R with an absorbing edge that mimics an agricultural field surrounded with fields of nonhost plants and bare land. It is found in the free space that epsilon (r|v) approximately e(-alphar/l), with alpha a function of l(d)/l, where l and l(d) are the scattering and deposition mean free paths, respectively. In the disk, however, epsilon (r|v) is an infinite series of Bessel functions and, exhibits three regimes: absorbing (Rl(d)).

Dual-Source Linear Energy Prediction (LINE-P) Model in the Context of WSNs.

Science.gov (United States)

Ahmed, Faisal; Tamberg, Gert; Le Moullec, Yannick; Annus, Paul

2017-07-20

Energy harvesting technologies such as miniature power solar panels and micro wind turbines are increasingly used to help power wireless sensor network nodes. However, a major drawback of energy harvesting is its varying and intermittent characteristic, which can negatively affect the quality of service. This calls for careful design and operation of the nodes, possibly by means of, e.g., dynamic duty cycling and/or dynamic frequency and voltage scaling. In this context, various energy prediction models have been proposed in the literature; however, they are typically compute-intensive or only suitable for a single type of energy source. In this paper, we propose Linear Energy Prediction "LINE-P", a lightweight, yet relatively accurate model based on approximation and sampling theory; LINE-P is suitable for dual-source energy harvesting. Simulations and comparisons against existing similar models have been conducted with low and medium resolutions (i.e., 60 and 22 min intervals/24 h) for the solar energy source (low variations) and with high resolutions (15 min intervals/24 h) for the wind energy source. The results show that the accuracy of the solar-based and wind-based predictions is up to approximately 98% and 96%, respectively, while requiring a lower complexity and memory than the other models. For the cases where LINE-P's accuracy is lower than that of other approaches, it still has the advantage of lower computing requirements, making it more suitable for embedded implementation, e.g., in wireless sensor network coordinator nodes or gateways.

A chemically selective laser ion source for the on-line isotope separation

International Nuclear Information System (INIS)

Scheerer, F.

1993-03-01

In this thesis a laser ion source is presented. In a hot chamber the atoms of the elements to be studied are resonantly by light of pulsed dye lasers, which are pumped by pulsed copper-vapor lasers with extremely high pulse repetition rate (ν rep ∼ 10 kHz), stepwise excited and ionized. By the storage of the atoms in a hot chamber and the high pulse repetition rate of the copper-vapor lasers beyond the required high efficiency (ε ∼ 10%) can be reached. First preparing measurements were performed at the off-line separator at CERN with the rare earth elements ytterbium and thulium. Starting from the results of these measurements further tests of the laser ion source were performed at the on-line separator with in a thick tantalum target produced neutron-deficient ytterbium isotopes. Under application of a time-of-flight mass spectrometer in Mainz an efficient excitation scheme on the resonance ionization of tin was found. This excitation scheme is condition for an experiment at the GSI for the production of the extremely neutron-deficient, short-lived nucleus 102 Sn. In the summer 1993 is as first application of the newly developed laser ion source at the PSB-ISOLDE at CERN an astrophysically relevant experiment for the nuclear spectroscopy of the neutron-rich silver isotopes 124-129 Ag is planned. This experiment can because of the lacking selectivity of conventional ion sources only be performed by means of the here presented laser ion source. The laser ion source shall at the PSB-ISOLDE 1993 also be applied for the selective ionization of manganese. (orig./HSI) [de

High-speed photonically assisted analog-to-digital conversion using a continuous wave multiwavelength source and phase modulation.

Science.gov (United States)

Bortnik, Bartosz J; Fetterman, Harold R

2008-10-01

A more simple photonically assisted analog-to-digital conversion system utilizing a cw multiwavelength source and phase modulation instead of a mode-locked laser is presented. The output of the cw multiwavelength source is launched into a dispersive device (such as a single-mode fiber). This fiber creates a pulse train, where the central wavelength of each pulse corresponds to a spectral line of the optical source. The pulses can then be either dispersed again to perform discrete wavelength time stretching or demultiplexed for continuous time analog-to-digital conversion. We experimentally demonstrate the operation of both time stretched and interleaved systems at 38 GHz. The potential of integrating this type of system on a monolithic chip is discussed.

Phonon dispersion evolution in uniaxially strained aluminum crystal

Science.gov (United States)

Parthasarathy, Ranganathan; Misra, Anil; Aryal, Sitaram; Ouyang, Lizhi

2018-04-01

The influence of loading upon the phonon dispersion of crystalline materials could be highly nonlinear with certain particular trends that depend upon the loading path. In this paper, we have calculated the influence of [100] uniaxial strain on the phonon dispersion and group velocities in fcc aluminum using second moments of position obtained from molecular dynamics (MD) simulation at 300 K. In contrast to nonlinear monotonic variation of both longitudinal and transverse phonon frequencies along the Δ , Λ and Σ lines of the first Brillouin zone under tension, transverse phonon branches along the Λ line show inflection at specific wavevectors when the compressive strain exceeds 5%. Further, the longitudinal group velocities along the high-symmetry Δ line vary non-monotonically with strain, reaching a minimum at 5% compressive strain. Throughout the strain range studied, the equilibrium positions of atoms displace in an affine manner preserving certain static structural symmetry. We attribute the anomalies in the phonon dispersion to the non-affine evolution of second moments of atomic position, and the associated plateauing of force constants under the applied strain path.

Energy dispersive X-ray fluorescence determination of cadmium in uranium matrix using Cd Kα line excited by continuum

International Nuclear Information System (INIS)

Dhara, Sangita; Misra, N.L.; Aggarwal, S.K.; Venugopal, V.

2010-01-01

An energy dispersive X-ray fluorescence method for determination of cadmium (Cd) in uranium (U) matrix using continuum source of excitation was developed. Calibration and sample solutions of cadmium, with and without uranium were prepared by mixing different volumes of standard solutions of cadmium and uranyl nitrate, both prepared in suprapure nitric acid. The concentration of Cd in calibration solutions and samples was in the range of 6 to 90 μg/mL whereas the concentration of Cd with respect to U ranged from 90 to 700 μg/g of U. From the calibration solutions and samples containing uranium, the major matrix uranium was selectively extracted using 30% tri-n-butyl phosphate in dodecane. Fixed volumes (1.5 mL) of aqueous phases thus obtained were taken directly in specially designed in-house fabricated leak proof Perspex sample cells for the energy dispersive X-ray fluorescence measurements and calibration plots were made by plotting Cd Kα intensity against respective Cd concentration. For the calibration solutions not having uranium, the energy dispersive X-ray fluorescence spectra were measured without any extraction and Cd calibration plots were made accordingly. The results obtained showed a precision of 2% (1σ) and the results deviated from the expected values by < 4% on average.

Some schemes for on-line correction of the closed orbit, dispersion and beta functions in PEP

International Nuclear Information System (INIS)

Donald, M.H.R.; Blocker, C.; Chao, A.W.; Hollebeek, R.J.; Lee, M.J.; Linstadt, J.E.; Siegrist, J.L.; Spencer, N.

1981-02-01

PEP has been operated successfully under computer control. It is necessary for colliding beam operation that the errors in closed orbits, dispersion and beta functions be corrected. The schemes in the PEP control program for on-line correction of these errors are described in this paper. The orbit control tasks in the PEP control system perform the functions of data gathering, data presentation (color display, printing), calculation and setting of corrector magnets. The tasks are generally small and modular, taking information from the database, processing it, then returning the results to the database. The PEP operator communicates with the tasks through touch panels monitored by the Director program. The display task, which displays orbit and corrector information on a TV color display, provides the main information required by the operator

Overview of major hazards. Part 2: Source term; dispersion; combustion; blast, missiles, venting; fire; radiation; runaway reactions; toxic substances; dust explosions

Science.gov (United States)

Vilain, J.

Approaches to major hazard assessment and prediction are reviewed. Source term: (phenomenology/modeling of release, influence on early stages of dispersion); dispersion (atmospheric advection, diffusion and deposition, emphasis on dense/cold gases); combustion (flammable clouds and mists covering flash fires, deflagration, transition to detonation; mostly unconfined/partly confined situations); blast formation, propagation, interaction with structures; catastrophic fires (pool fires, torches and fireballs; highly reactive substances) runaway reactions; features of more general interest; toxic substances, excluding toxicology; and dust explosions (phenomenology and protective measures) are discussed.

Influence of local parameters on the dispersion of traffic-related pollutants within street canyons

Science.gov (United States)

Karra, Styliani; Malki-Epshtein, Liora; Martin Hyde Collaboration

2011-11-01

Ventilation within urban cities and street canyons and the associated air quality is a problem of increasing interest in the last decades. It is important for to minimise exposure of the population to traffic-related pollutants at street level. The residence time of pollutants within the street canyons depends on the meteorological conditions such as wind speed and direction, geometry layout and local parameters (position of traffic lane within the street). An experimental study was carried out to investigate the influence of traffic lane position on the dispersion of traffic-related pollutants within different street canyons geometries: symmetrical (equal building heights on both sides of the street), non-symmetrical (uniform building heights but lower on one side of the street) and heterogeneous (non-uniform building heights on both sides of the street) under constant meteorological conditions. Laboratory experiments were carried out within a water channel and simultaneous measurements of velocity field and concentration scalar levels within and above the street canyons using PIV and PLIF techniques. Traffic -related emissions were simulated using a line emission source. Two positions were examined for all street geometries: line emission source was placed in the centre of the street canyon; line emission source was placed off the centre of the street. TSI Incorporated.

Long-distance wind-dispersal of spores in a fungal plant pathogen: estimation of anisotropic dispersal kernels from an extensive field experiment.

Directory of Open Access Journals (Sweden)

Adrien Rieux

Full Text Available Given its biological significance, determining the dispersal kernel (i.e., the distribution of dispersal distances of spore-producing pathogens is essential. Here, we report two field experiments designed to measure disease gradients caused by sexually- and asexually-produced spores of the wind-dispersed banana plant fungus Mycosphaerella fijiensis. Gradients were measured during a single generation and over 272 traps installed up to 1000 m along eight directions radiating from a traceable source of inoculum composed of fungicide-resistant strains. We adjusted several kernels differing in the shape of their tail and tested for two types of anisotropy. Contrasting dispersal kernels were observed between the two types of spores. For sexual spores (ascospores, we characterized both a steep gradient in the first few metres in all directions and rare long-distance dispersal (LDD events up to 1000 m from the source in two directions. A heavy-tailed kernel best fitted the disease gradient. Although ascospores distributed evenly in all directions, average dispersal distance was greater in two different directions without obvious correlation with wind patterns. For asexual spores (conidia, few dispersal events occurred outside of the source plot. A gradient up to 12.5 m from the source was observed in one direction only. Accordingly, a thin-tailed kernel best fitted the disease gradient, and anisotropy in both density and distance was correlated with averaged daily wind gust. We discuss the validity of our results as well as their implications in terms of disease diffusion and management strategy.

Measuring short distance dispersal of Alliaria petiolata and determining potential long distance dispersal mechanisms

Directory of Open Access Journals (Sweden)

Christopher A. Loebach

2018-03-01

Full Text Available Introduction Alliaria petiolata, an herbaceous plant, has invaded woodlands in North America. Its ecology has been thoroughly studied, but an overlooked aspect of its biology is seed dispersal distances and mechanisms. We measured seed dispersal distances in the field and tested if epizoochory is a potential mechanism for long-distance seed dispersal. Methods Dispersal distances were measured by placing seed traps in a sector design around three seed point sources, which consisted of 15 second-year plants transplanted within a 0.25 m radius circle. Traps were placed at intervals ranging from 0.25–3.25 m from the point source. Traps remained in the field until a majority of seeds were dispersed. Eight probability density functions were fitted to seed trap counts via maximum likelihood. Epizoochory was tested as a potential seed dispersal mechanism for A. petiolata through a combination of field and laboratory experiments. To test if small mammals transport A. petiolata seeds in their fur, experimental blocks were placed around dense A. petiolata patches. Each block contained a mammal inclusion treatment (MIT and control. The MIT consisted of a wood-frame (31 × 61× 31 cm covered in wire mesh, except for the two 31 × 31 cm ends, placed over a germination tray filled with potting soil. A pan filled with bait was placed in the center of the tray. The control frame (11 × 31 × 61 cm was placed over a germination tray and completely covered in wire mesh to exclude animal activity. Treatments were in the field for peak seed dispersal. In March, trays were moved to a greenhouse and A. petiolata seedlings were counted and then compared between treatments. To determine if A. petiolata seeds attach to raccoon (Procyon lotor and white-tailed deer (Odocoileus virginianus fur, wet and dry seeds were dropped onto wet and dry fur. Furs were rotated 180 degrees and the seeds that remained attached were counted. To measure seed retention, seeds

Elimination of C3 as the Bond-Neff depression opacity source in Hr 774

International Nuclear Information System (INIS)

Baird, S.R.

1982-01-01

The pseudocontinuum of C 3 has been proposed by Fix as the source of the Bond-Neff depression in HR 774. In such a case the strongest rotational lines of the 4050 A vibrational band of C 3 should be clearly evident at high dispersion. A 2.2 A mm -1 plate of HR 774 is examined in the 4050--4060 A region where the strongest lines should form. The absence of C 3 rotational lines indicates that C 3 cannot be the major contributor to the Bond-Neff depression in HR 774

Spectral lines and characteristic of temporal variations in photoionized plasmas induced with laser-produced plasma extreme ultraviolet source

Science.gov (United States)

Saber, I.; Bartnik, A.; Wachulak, P.; Skrzeczanowski, W.; Jarocki, R.; Fiedorowicz, H.

2017-11-01

Spectral lines for Kr/Ne/H2 photoionized plasma in the ultraviolet and visible (UV/Vis) wavelength ranges have been created using a laser-produced plasma (LPP) EUV source. The source is based on a double-stream gas puff target irradiated with a commercial Nd:YAG laser. The laser pulses were focused onto a gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Spectral lines from photoionization in neutral Kr/Ne/H2 and up to few charged states were observed. The intense emission lines were associated with the Kr transition lines. Experimental and theoretical investigations on intensity variations for some ionic lines are presented. A decrease in the intensity with the delay time between the laser pulse and the spectrum acquisition was revealed. Electron temperature and electron density in the photoionized plasma have been estimated from the characteristic emission lines. Temperature was obtained using Boltzmann plot method, assuming that the population density of atoms and ions are considered in a local thermodynamic equilibrium (LTE). Electron density was calculated from the Stark broadening profile. The temporal evaluation of the plasma and the way of optimizing the radiation intensity of LPP EUV sources is discussed.

An experimental study of the impact of trees and urban form on the turbulent dispersion of heavy particles from near ground point sources

Science.gov (United States)

Stoll, R., II; Christen, A.; Mahaffee, W.; Salesky, S.; Therias, A.; Caitlin, S.

2017-12-01

Pollution in the form of small particles has a strong impact on a wide variety of urban processes that play an important role in the function of urban ecosystems and ultimately human health and well-being. As a result, a substantial body of research exists on the sources, sinks, and transport characteristics of urban particulate matter. Most of the existing experimental work examining point sources employed gases (e.g., SF6) as the working medium. Furthermore, the focus of most studies has been on the dispersion of pollutants far from the source location. Here, our focus is on the turbulent dispersion of heavy particles in the near source region of a suburban neighborhood. To this end, we conducted a series of heavy particle releases in the Sunset neighborhood of Vancouver, Canada during June, 2017. The particles where dispersed from a near ground point source at two different locations. The Sunset neighborhood is composed mostly of single dwelling detached houses and has been used in numerous previous urban studies. One of the release points was just upwind of a 4-way intersection and the other in the middle of a contiguous block of houses. Each location had a significant density of trees. A minimum of four different successful release events were conducted at each site. During each release, fluorescing micro particles (mean diameter approx. 30 micron) were released from ultrasonic atomizer nozzles for a duration of approximately 20 minutes. The particles where sampled at 50 locations (1.5 m height) in the area downwind of the release over distances from 1-15 times the mean canopy height ( 6 m) using rotating impaction traps. In addition to the 50 sampler locations, instantaneous wind velocities were measured with eight sonic anemometers distributed horizontally and vertically throughout the release area. The resulting particle plume distributions indicate a strong impact of local urban form in the near source region and a high degree of sensitivity to the local

Assessing risk from low energy radionuclide aerosol dispersal

International Nuclear Information System (INIS)

Waller, Edward; Perera, Sharman; Erhardt, Lorne; Cousins, Tom; Desrosiers, Marc

2008-01-01

Full text: When considering the potential dispersal of radionuclides into the environment, there are two broad classifications: explosive and non-explosive dispersal. An explosive dispersal relies on a violent and sudden release of energy, which may disrupt or vapourised any source containment. As such, the explosion provides the energy to both convert the source into a dispersable physical form and provides initial kinetic energy to transport the source away from the initiation point. This would be the case for sources of radiation in proximity to a steam or chemical explosion of high energy density. A low energy dispersal, on the other hand, may involve a lower energy initiator event (such as a fire or water spray) that transports particles into the near release zone, to be spread via wind or mechanical fields. For this type of dispersion to take place, the source must be in physical form ready for dispersal. In broad terms, this suggests either an ab initio powder form, or soluble/insoluble particulate form in a liquid matrix. This may be the case for radioactive material released from pressurized piping systems, material released through ventilation systems, or deliberate dispersals. To study aerosol dispersion of radionuclides and risk from low energy density initiators, there are a number of important parameters to consider. For example, particle size distribution, physicochemical form, atmospheric effects, charge effects, coagulation and agglomeration. At the University of Ontario Institute of Technology (UOIT) a unique small scale aerosol test chamber has been developed to study the low energy dispersal properties of a number of radioactive source simulant. Principle emphasis has been given to salts (CsCl and CoCl 2 ) and oxides (SrTiO 3 , CeO 2 and EuO 2 ). A planetary ball mill has been utilized to reduce particle size distributions when required. Particle sizing has been performed using Malvern Spraytec spray particle analyzers, cascade impactors, and

Gaseous detectors for energy dispersive X-ray fluorescence analysis

Science.gov (United States)

Veloso, J. F. C. A.; Silva, A. L. M.

2018-01-01

The energy resolution capability of gaseous detectors is being used in the last years to perform studies on the detection of characteristic X-ray lines emitted by elements when excited by external radiation sources. One of the most successful techniques is the Energy Dispersive X-ray Fluorescence (EDXRF) analysis. Recent developments in the new generation of micropatterned gaseous detectors (MPGDs), triggered the possibility not only of recording the photon energy, but also of providing position information, extending their application to EDXRF imaging. The relevant features and strategies to be applied in gaseous detectors in order to better fit the requirements for EDXRF imaging will be reviewed and discussed, and some application examples will be presented.

A source term estimation method for a nuclear accident using atmospheric dispersion models

DEFF Research Database (Denmark)

Kim, Minsik; Ohba, Ryohji; Oura, Masamichi

2015-01-01

The objective of this study is to develop an operational source term estimation (STE) method applicable for a nuclear accident like the incident that occurred at the Fukushima Dai-ichi nuclear power station in 2011. The new STE method presented here is based on data from atmospheric dispersion...... models and short-range observational data around the nuclear power plants.The accuracy of this method is validated with data from a wind tunnel study that involved a tracer gas release from a scaled model experiment at Tokai Daini nuclear power station in Japan. We then use the methodology developed...... and validated through the effort described in this manuscript to estimate the release rate of radioactive material from the Fukushima Dai-ichi nuclear power station....

Dispersion and betatron function correction in the Advanced Photon Source storage ring using singular value decomposition

International Nuclear Information System (INIS)

Emery, L.

1999-01-01

Magnet errors and off-center orbits through sextuples perturb the dispersion and beta functions in a storage ring (SR), which affects machine performance. In a large ring such as the Advanced Photon Source (APS), the magnet errors are difficult to determine with beam-based methods. Also the non-zero orbit through sextuples result from user requests for steering at light source points. For expediency, a singular value decomposition (SVD) matrix method analogous to orbit correction was adopted to make global corrections to these functions using strengths of several quadrupoles as correcting elements. The direct response matrix is calculated from the model of the perfect lattice. The inverse is calculated by SVD with a selected number of singular vectors. Resulting improvement in the lattice functions and machine performance will be presented

CANDIDATE WATER VAPOR LINES TO LOCATE THE H{sub 2}O SNOWLINE THROUGH HIGH-DISPERSION SPECTROSCOPIC OBSERVATIONS. I. THE CASE OF A T TAURI STAR

Energy Technology Data Exchange (ETDEWEB)

Notsu, Shota; Ishimoto, Daiki [Department of Astronomy, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Nomura, Hideko [Department of Earth and Planetary Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Walsh, Catherine [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Honda, Mitsuhiko [Department of Physics, School of Medicine, Kurume University, 67 Asahi-machi, Kurume, Fukuoka 830-0011 (Japan); Hirota, Tomoya [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Millar, T. J., E-mail: snotsu@kusastro.kyoto-u.ac.jp [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast, BT7 1NN (United Kingdom)

2016-08-20

Inside the H{sub 2}O snowline of protoplanetary disks, water evaporates from the dust-grain surface into the gas phase, whereas it is frozen out onto the dust in the cold region beyond the snowline. H{sub 2}O ice enhances the solid material in the cold outer part of a disk, which promotes the formation of gas-giant planet cores. We can regard the H{sub 2}O snowline as the surface that divides the regions between rocky and gaseous giant planet formation. Thus observationally measuring the location of the H{sub 2}O snowline is crucial for understanding the planetesimal and planet formation processes, and the origin of water on Earth. In this paper, we find candidate water lines to locate the H{sub 2}O snowline through future high-dispersion spectroscopic observations. First, we calculate the chemical composition of the disk and investigate the abundance distributions of H{sub 2}O gas and ice, and the position of the H{sub 2}O snowline. We confirm that the abundance of H{sub 2}O gas is high not only in the hot midplane region inside the H{sub 2}O snowline but also in the hot surface layer of the outer disk. Second, we calculate the H{sub 2}O line profiles and identify those H{sub 2}O lines that are promising for locating the H{sub 2}O snowline: the identified lines are those that have small Einstein A coefficients and high upper state energies. The wavelengths of the candidate H{sub 2}O lines range from mid-infrared to sub-millimeter, and they overlap with the regions accessible to the Atacama Large Millimeter/sub-millimeter Array and future mid-infrared high-dispersion spectrographs (e.g., TMT/MICHI, SPICA).

A completely automatic operation type super-safe fast reactor, RAPID. Its application to dispersion source on lunar and earth surfaces

International Nuclear Information System (INIS)

Kanbe, Mitsuru; Tsunoda, Hirokazu; Mishima, Kaichiro; Kawasaki, Akira; Iwamura, Takamichi

2002-01-01

At a viewpoint of flexible measures to future electric power demands, expectation onto a small-scale reactor for dispersion source is increasing gradually. This is thought to increase its importance not only for a source at proximity of its market in advanced nations but also for the one in developing nations. A study on development of the completely automatic operation type super-safe fast reactor, RAPID (refueling by all pins integrated design) has been carried out as a part of the nuclear energy basic research promoting system under three years project since 1999 by a trust of the Japan Atomic Energy Research Institute to a group of the Central Research Institute of Electric Power Industry (CRIEPI) and so on. As the reactor is a lithium cooled fast reactor with 200 Kw of electric output supposing to use at lunar surface, it can be applied to a super-small scale nuclear reactor on the earth, and has feasibility to become a new option of future nuclear power generation. On the other hand, CRIEPI has investigated on various types of fast reactors (RAPID series) for fast reactor for dispersion source on the earth. Here was introduced on such super-safe fast reactors at a center of RAPID-L. (G.K.)

Quad Cities Unit 2 Main Steam Line Acoustic Source Identification and Load Reduction

International Nuclear Information System (INIS)

DeBoo, Guy; Ramsden, Kevin; Gesior, Roman

2006-01-01

The Quad Cities Units 1 and 2 have a history of steam line vibration issues. The implementation of an Extended Power Up-rate resulted in significant increases in steam line vibration as well as acoustic loading of the steam dryers, which led to equipment failures and fatigue cracking of the dryers. This paper discusses the results of extensive data collection on the Quad Cities Unit 2 replacement dryer and the Main Steam Lines. This data was taken with the intent of identifying acoustic sources in the steam system. Review of the data confirmed that vortex shedding coupled column resonance in the relief and safety valve stub pipes were the principal sources of large magnitude acoustic loads in the main steam system. Modifications were developed in sub-scale testing to alter the acoustic properties of the valve standpipes and add acoustic damping to the system. The modifications developed and installed consisted of acoustic side branches that were attached to the Electromatic Relief Valve (ERV) and Main Steam Safety Valve (MSSV) attachment pipes. Subsequent post-modification testing was performed in plant to confirm the effectiveness of the modifications. The modifications have been demonstrated to reduce vibration loads at full Extended Power Up-rate (EPU) conditions to levels below those at Original Licensed Thermal Power (OLTP). (authors)

Integration of measurements with atmospheric dispersion models: Source term estimation for dispersal of (239)Pu due to non-nuclear detonation of high explosive

Science.gov (United States)

Edwards, L. L.; Harvey, T. F.; Freis, R. P.; Pitovranov, S. E.; Chernokozhin, E. V.

1992-10-01

The accuracy associated with assessing the environmental consequences of an accidental release of radioactivity is highly dependent on our knowledge of the source term characteristics and, in the case when the radioactivity is condensed on particles, the particle size distribution, all of which are generally poorly known. This paper reports on the development of a numerical technique that integrates the radiological measurements with atmospheric dispersion modeling. This results in a more accurate particle-size distribution and particle injection height estimation when compared with measurements of high explosive dispersal of (239)Pu. The estimation model is based on a non-linear least squares regression scheme coupled with the ARAC three-dimensional atmospheric dispersion models. The viability of the approach is evaluated by estimation of ADPIC model input parameters such as the ADPIC particle size mean aerodynamic diameter, the geometric standard deviation, and largest size. Additionally we estimate an optimal 'coupling coefficient' between the particles and an explosive cloud rise model. The experimental data are taken from the Clean Slate 1 field experiment conducted during 1963 at the Tonopah Test Range in Nevada. The regression technique optimizes the agreement between the measured and model predicted concentrations of (239)Pu by varying the model input parameters within their respective ranges of uncertainties. The technique generally estimated the measured concentrations within a factor of 1.5, with the worst estimate being within a factor of 5, very good in view of the complexity of the concentration measurements, the uncertainties associated with the meteorological data, and the limitations of the models. The best fit also suggest a smaller mean diameter and a smaller geometric standard deviation on the particle size as well as a slightly weaker particle to cloud coupling than previously reported.

Integration of measurements with atmospheric dispersion models: Source term estimation for dispersal of 239Pu due to non- nuclear detonation of high explosive

International Nuclear Information System (INIS)

Edwards, L.L.; Harvey, T.F.; Freis, R.P.; Pitovranov, S.E.; Chernokozhin, E.V.

1992-10-01

The accuracy associated with assessing the environmental consequences of an accidental release of radioactivity is highly dependent on our knowledge of the source term characteristics and, in the case when the radioactivity is condensed on particles, the particle size distribution, all of which are generally poorly known. This paper reports on the development of a numerical technique that integrates the radiological measurements with atmospheric dispersion modeling. This results in a more accurate particle-size distribution and particle injection height estimation when compared with measurements of high explosive dispersal of 239 Pu. The estimation model is based on a non-linear least squares regression scheme coupled with the ARAC three-dimensional atmospheric dispersion models. The viability of the approach is evaluated by estimation of ADPIC model input parameters such as the ADPIC particle size mean aerodynamic diameter, the geometric standard deviation, and largest size. Additionally we estimate an optimal ''coupling coefficient'' between the particles and an explosive cloud rise model. The experimental data are taken from the Clean Slate 1 field experiment conducted during 1963 at the Tonopah Test Range in Nevada. The regression technique optimizes the agreement between the measured and model predicted concentrations of 239 Pu by varying the model input parameters within their respective ranges of uncertainties. The technique generally estimated the measured concentrations within a factor of 1.5, with the worst estimate being within a factor of 5, very good in view of the complexity of the concentration measurements, the uncertainties associated with the meteorological data, and the limitations of the models. The best fit also suggest a smaller mean diameter and a smaller geometric standard deviation on the particle size as well as a slightly weaker particle to cloud coupling than previously reported

Modelling airborne dispersion of coarse particulate material

International Nuclear Information System (INIS)

Apsley, D.D.

1989-03-01

Methods of modelling the airborne dispersion and deposition of coarse particulates are presented, with the emphasis on the heavy particles identified as possible constituents of releases from damaged AGR fuel. The first part of this report establishes the physical characteristics of the irradiated particulate in airborne emissions from AGR stations. The second part is less specific and describes procedures for extending current dispersion/deposition models to incorporate a coarse particulate component: the adjustment to plume spread parameters, dispersion from elevated sources and dispersion in conjunction with building effects and plume rise. (author)

Modeling the generation and dispersion of odors from mushroom composting facilities

International Nuclear Information System (INIS)

Heinemann, P.; Wahanik, D.

1998-01-01

An odor source generation model and an odor dispersion model were developed to predict the local distribution of odors emanating from mushroom composting facilities. The odor source generation model allowed for simulation of various composting wharf configurations and odor source strengths. This model was linked to a Gaussian plume diffusion model that predicted odor dispersion. Dimethyl disulfide production at a rate of 1760 micrograms/h was simulated by the source generation model and six different atmospheric conditions were analyzed to demonstrate the effect of wind speed, atmospheric stability, and source generation on the dispersion of this odor producing compound. Detectable levels of dimethyl disulfide were predicted to range from less than 100 m from the source during very unstable conditions to almost 5000 m during very stable conditions

Offshore and coastal dispersion (OCD) model. Users guide

International Nuclear Information System (INIS)

Hanna, S.R.; Schulman, L.L.; Paine, R.J.; Pleim, J.E.

1984-09-01

The Offshore and Coastal Dispersion (OCD) model was adapted from the EPA guideline model MPTER to simulate the effect of offshore emissions from point sources in coastal regions. Modifications were made to incorporate overwater plume transport and dispersion as well as changes that occur as the plume crosses the shoreline. Hourly meteorological data are needed from overwater and overland locations. Turbulence intensities are used but are not mandatory. For overwater dispersion, the turbulence intensities are parameterized from boundary-layer similarity relationships if they are not measured. Specifications of emission characteristics and receptor locations are the same as for MPTER; 250 point sources and 180 receptors may be used

Stellar Velocity Dispersion: Linking Quiescent Galaxies to Their Dark Matter Halos

Science.gov (United States)

Zahid, H. Jabran; Sohn, Jubee; Geller, Margaret J.

2018-06-01

We analyze the Illustris-1 hydrodynamical cosmological simulation to explore the stellar velocity dispersion of quiescent galaxies as an observational probe of dark matter halo velocity dispersion and mass. Stellar velocity dispersion is proportional to dark matter halo velocity dispersion for both central and satellite galaxies. The dark matter halos of central galaxies are in virial equilibrium and thus the stellar velocity dispersion is also proportional to dark matter halo mass. This proportionality holds even when a line-of-sight aperture dispersion is calculated in analogy to observations. In contrast, at a given stellar velocity dispersion, the dark matter halo mass of satellite galaxies is smaller than virial equilibrium expectations. This deviation from virial equilibrium probably results from tidal stripping of the outer dark matter halo. Stellar velocity dispersion appears insensitive to tidal effects and thus reflects the correlation between stellar velocity dispersion and dark matter halo mass prior to infall. There is a tight relation (≲0.2 dex scatter) between line-of-sight aperture stellar velocity dispersion and dark matter halo mass suggesting that the dark matter halo mass may be estimated from the measured stellar velocity dispersion for both central and satellite galaxies. We evaluate the impact of treating all objects as central galaxies if the relation we derive is applied to a statistical ensemble. A large fraction (≳2/3) of massive quiescent galaxies are central galaxies and systematic uncertainty in the inferred dark matter halo mass is ≲0.1 dex thus simplifying application of the simulation results to currently available observations.

Sourcing human embryos for embryonic stem cell lines: Problems & perspectives

Directory of Open Access Journals (Sweden)

Rajvi H Mehta

2014-01-01

Full Text Available The ability to successfully derive human embryonic stem cells (hESC lines from human embryos following in vitro fertilization (IVF opened up a plethora of potential applications of this technique. These cell lines could have been successfully used to increase our understanding of human developmental biology, transplantation medicine and the emerging science of regenerative medicine. The main source for human embryos has been ′discarded′ or ′spare′ fresh or frozen human embryos following IVF. It is a common practice to stimulate the ovaries of women undergoing any of the assisted reproductive technologies (ART and retrieve multiple oocytes which subsequently lead to multiple embryos. Of these, only two or maximum of three embryos are transferred while the rest are cryopreserved as per the decision of the couple. In case a couple does not desire to ′cryopreserve′ their embryos then all the embryos remaining following embryo transfer can be considered ′spare′ or if a couple is no longer in need of the ′cryopreserved′ embryos then these also can be considered as ′spare′. But, the question raised by the ethicists is, "what about ′slightly′ over-stimulating a woman to get a few extra eggs and embryos? The decision becomes more difficult when it comes to ′discarded′ embryos. As of today, the quality of the embryos is primarily assessed based on morphology and the rate of development mainly judged by single point assessment. Despite many criteria described in the literature, the quality assessment is purely subjective. The question that arises is on the decision of ′discarding′ embryos. What would be the criteria for discarding embryos and the potential ′use′ of ESC derived from the ′abnormal appearing′ embryos? This paper discusses some of the newer methods to procure embryos for the derivation of embryonic stem cell lines which will respect the ethical concerns but still provide the source material.

Pollutant Plume Dispersion over Hypothetical Urban Areas based on Wind Tunnel Measurements

Science.gov (United States)

Mo, Ziwei; Liu, Chun-Ho

2017-04-01

Gaussian plume model is commonly adopted for pollutant concentration prediction in the atmospheric boundary layer (ABL). However, it has a number of limitations being applied to pollutant dispersion over complex land-surface morphology. In this study, the friction factor (f), as a measure of aerodynamic resistance induced by rough surfaces in the engineering community, was proposed to parameterize the vertical dispersion coefficient (σz) in the Gaussian model. A series of wind tunnel experiments were carried out to verify the mathematical hypothesis and to characterize plume dispersion as a function of surface roughness as well. Hypothetical urban areas, which were assembled in the form of idealized street canyons of different aspect (building-height-to-street-width) ratios (AR = 1/2, 1/4, 1/8 and 1/12), were fabricated by aligning identical square aluminum bars at different separation apart in cross flows. Pollutant emitted from a ground-level line source into the turbulent boundary layer (TBL) was simulated using water vapour generated by ultrasonic atomizer. The humidity and the velocity (mean and fluctuating components) were measured, respectively, by humidity sensors and hot-wire anemometry (HWA) with X-wire probes in streamwise and vertical directions. Wind tunnel results showed that the pollutant concentration exhibits the conventional Gaussian distribution, suggesting the feasibility of using water vapour as a passive scalar in wind tunnel experiments. The friction factor increased with decreasing aspect ratios (widening the building separation). It was peaked at AR = 1/8 and decreased thereafter. Besides, a positive correlation between σz/xn (x is the distance from the pollutant source) and f1/4 (correlation coefficient r2 = 0.61) was observed, formulating the basic parameterization of plume dispersion over urban areas.

National Synchrotron Light Source users manual: Guide to the VUV and x-ray beam lines

International Nuclear Information System (INIS)

Gmuer, N.F.; White-DePace, S.M.

1987-08-01

The success of the National Synchrotron Light Source in the years to come will be based, in large part, on the size of the users community and the diversity of the scientific disciplines represented by these users. In order to promote this philosophy, this National Synchrotron Light Source (NSLS) Users Manual: Guide to the VUV and X-Ray Beam Lines, has been published. This manual serves a number of purposes. In an effort to attract new research, it will present to the scientific community-at-large the current and projected architecture and capabilities of the various VUV and x-ray beam lines and storage rings. We anticipate that this publication will be updated periodically in order to keep pace with the constant changes at the NSLS

Fast Running Urban Dispersion Model for Radiological Dispersal Device (RDD) Releases: Model Description and Validation

Energy Technology Data Exchange (ETDEWEB)

Gowardhan, Akshay [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Neuscamman, Stephanie [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Donetti, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Walker, Hoyt [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Belles, Rich [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Eme, Bill [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Homann, Steven [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Simpson, Matthew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Nasstrom, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC)

2017-05-24

Aeolus is an efficient three-dimensional computational fluid dynamics code based on finite volume method developed for predicting transport and dispersion of contaminants in a complex urban area. It solves the time dependent incompressible Navier-Stokes equation on a regular Cartesian staggered grid using a fractional step method. It also solves a scalar transport equation for temperature and using the Boussinesq approximation. The model also includes a Lagrangian dispersion model for predicting the transport and dispersion of atmospheric contaminants. The model can be run in an efficient Reynolds Average Navier-Stokes (RANS) mode with a run time of several minutes, or a more detailed Large Eddy Simulation (LES) mode with run time of hours for a typical simulation. This report describes the model components, including details on the physics models used in the code, as well as several model validation efforts. Aeolus wind and dispersion predictions are compared to field data from the Joint Urban Field Trials 2003 conducted in Oklahoma City (Allwine et al 2004) including both continuous and instantaneous releases. Newly implemented Aeolus capabilities include a decay chain model and an explosive Radiological Dispersal Device (RDD) source term; these capabilities are described. Aeolus predictions using the buoyant explosive RDD source are validated against two experimental data sets: the Green Field explosive cloud rise experiments conducted in Israel (Sharon et al 2012) and the Full-Scale RDD Field Trials conducted in Canada (Green et al 2016).

On the influence of the finite thickness of sources on the internal conversion lines observed in beta spectrometer

International Nuclear Information System (INIS)

Pecequilo, B.R.S.

1976-01-01

Electron lines are simulated by a Monte Carlo method in a digital computer in order to obtain an analytical formula to calculate the energy and the relative intensity of electron conversion lines when observed by beta spectrometry. The electrons come from the own thickness of the source. Computer program that simulate these lines is presented. In order to test the method, a direct comparison of the K-line of Hg-198 with the same line as simulated by the computer, is done [pt

Blended acquisition with dispersed source arrays

NARCIS (Netherlands)

Berkhout, A.J.

2012-01-01

Blended source arrays are historically configured with equal source units, such as broadband vibrators (land) and broadband air-gun arrays (marine). I refer to this concept as homogeneous blending. I have proposed to extend the blending concept to inhomogeneous blending, meaning that a blended

Dispersion factors - tables and diagrams for the Karlsruhe site

International Nuclear Information System (INIS)

Papadopoulos, D.; Baer, M.; Honcu, S.

1984-02-01

Dispersion experiments were performed at the Nuclear Research Center for the Karlsruhe site. The evaluation of these experiments allowed to determine the parameters of lateral or vertical atmospheric dispersions. This report is a compilation of tables and diagrams showing the dispersion factors calculated with the help of the dispersion parameters. These dispersion factors are valid for the Karlsruhe site. They have been normalized to 1 m/s wind speed and to 1 g/s (or 1 Bq/s) source strength. (orig.) [de

Status and Needs Research for On-line Monitoring of VOCs Emissions from Stationary Sources

Science.gov (United States)

Zhou, Gang; Wang, Qiang; Zhong, Qi; Zhao, Jinbao; Yang, Kai

2018-01-01

Based on atmospheric volatile organic compounds (VOCs) pollution control requirements during the twelfth-five year plan and the current status of monitoring and management at home and abroad, instrumental architecture and technical characteristics of continuous emission monitoring systems (CEMS) for VOCs emission from stationary sources are investigated and researched. Technological development needs of VOCs emission on-line monitoring techniques for stationary sources in china are proposed from the system sampling pretreatment technology and analytical measurement techniques.

Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

Energy Technology Data Exchange (ETDEWEB)

Katata, G.; Chino, M.; Kobayashi, T. [Japan Atomic Energy Agency (JAEA), Ibaraki (Japan); and others

2015-07-01

Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric and oceanic transport, dispersion and deposition models. The atmospheric and oceanic models used are WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN-FDM (Finite difference oceanic dispersion model), both developed by the authors. A sophisticated deposition scheme, which deals with dry and fog-water depositions, cloud condensation nuclei (CCN) activation, and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I{sub 2} and CH{sub 3}I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The results revealed that the major releases of radionuclides due to the FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, midnight of 14 March when the SRV (safety relief valve) was opened three times at Unit 2, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of release rates. The simulation by WSPEEDI-II using the new source term reproduced the local and regional patterns of

X-ray photoelectron microscope with a compact x-ray source generated by line-focused laser irradiation

International Nuclear Information System (INIS)

Yamaguchi, N.; Okamoto, Y.; Hara, T.; Takahashi, Z.; Nishimura, Y.; Sakata, A.; Watanabe, K.; Azuma, H.

2004-01-01

Full text: A laboratory-sized microscopic system of x-ray photoelectrons has been developing using a compact x-ray source produced by line-focused laser irradiation. The system is a scanning type photoelectron microscope where x-ray beam is micro-focused via a Schwartzschild optics. A compact laser-plasma x-ray source has been developed with a YAG laser system, a line-focus lens system, a tape-target driving system and a debris prevention system, that was operated at repetition rate of 10 Hz or 50 Hz. X-rays were delivered along line plasma whose length was 0.6 to 11 mm with higher intensity than that from a point-focused source. Because the transition line of Al V (13.1 nm) was prominent in the soft x-ray spectrum when the Al tape target irradiated at the lower power density of 10 11 W/cm 2 , the 13.1 nm x-ray was used as an excitation source. The Schwartzschild optics was set on the beamline at a distance about 1 m from the source, which was coated with Mo/Si multilayers for 13.1 nm x-ray. The designed demagnification is 224 that was confirmed in the previous experiment. Therefore, an x-ray micro spot of sub-micron size can be formed on a sample surface when the source size is less than about 0.2 mm. Samples were set on a two-axis high-precision piezo stage mounted to a four-axis manipulator. The electron energy analyzer was a spherical capacitor analyzer with mean diameter of 279.4 mm. The electron detector was a microchannel plate (MCP) with a phosphor screen and the optical image of electrons on the exit plane of the analyzer was taken and recorded by using an ultra low dark noise CCD camera, that was suited for detection of vast photoelectrons excited by x-ray pulse of ns-order duration. We performed spatial resolution test measurements by using a GaAs wafer coated with photo-resist that formed a stripe pattern. The spatial resolution less than 3 micron has been obtained from the variation of As 3d electron intensity along the position of the GaAs sample

Kinetics of Low Temperature Polyester Dyeing with High Molecular Weight Disperse Dyes by Solvent Microemulsion and AgroSourced Auxiliaries

Directory of Open Access Journals (Sweden)

Shahram Radei

2018-02-01

Full Text Available This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of n-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100 °C. Moreover, the dyeing rate constants, correlation coefficient and activation energies were proposed for this system. It was found that o-vanillin yielded higher dye absorption levels than coumarin, leading to exhaustions of 88% and 87% for Disperse Red 167 and Disperse Blue 79, respectively. K/S values of dyed polyester were also found to be higher for dye baths containing o-vanillin with respect to the ones with coumarin. In terms of hot pressing fastness and wash fastness, generally no adverse influence on fastness properties was reported, while o-vanillin showed slightly better results compared to coumarin.

A catalog of pre-main-sequence emission-line stars with IRAS source associations

International Nuclear Information System (INIS)

Weintraub, D.A.

1990-01-01

To aid in finding premain-sequence (PMS) emission-line stars that might have dusty circumstellar environments, 361 PMS stars that are associated with 304 separate IRAS sources were identified. These stars include 200 classical T Tauri stars, 25 weak-lined (naked) T Tauri stars, 56 Herbig Ae/Be stars, six FU Orionis stars, and two SU Aurigae stars. All six of the FU Orionis stars surveyed by IRAS were detected. Of the PMS-IRAS Point Source Catalog (PSC) associations, 90 are new and are not noted in the PSC. The other 271 entries include 104 that are correctly identified in the PSC but have not yet appeared in the literature, 56 more that can be found in both the PSC and in the published and unpublished iterature, and 111 that are in the literature but not in the PSC. Spectral slope diagrams constructed from the 12-, 25-, and 60-micron flux densities reveal unique distributions for the different PMS subclasses; these diagrams may help identify the best candidate PMS stars for observations of circumstellar dust. 30 refs

Sensitivity analysis of the near-road dispersion model RLINE - An evaluation at Detroit, Michigan

Science.gov (United States)

Milando, Chad W.; Batterman, Stuart A.

2018-05-01

The development of accurate and appropriate exposure metrics for health effect studies of traffic-related air pollutants (TRAPs) remains challenging and important given that traffic has become the dominant urban exposure source and that exposure estimates can affect estimates of associated health risk. Exposure estimates obtained using dispersion models can overcome many of the limitations of monitoring data, and such estimates have been used in several recent health studies. This study examines the sensitivity of exposure estimates produced by dispersion models to meteorological, emission and traffic allocation inputs, focusing on applications to health studies examining near-road exposures to TRAP. Daily average concentrations of CO and NOx predicted using the Research Line source model (RLINE) and a spatially and temporally resolved mobile source emissions inventory are compared to ambient measurements at near-road monitoring sites in Detroit, MI, and are used to assess the potential for exposure measurement error in cohort and population-based studies. Sensitivity of exposure estimates is assessed by comparing nominal and alternative model inputs using statistical performance evaluation metrics and three sets of receptors. The analysis shows considerable sensitivity to meteorological inputs; generally the best performance was obtained using data specific to each monitoring site. An updated emission factor database provided some improvement, particularly at near-road sites, while the use of site-specific diurnal traffic allocations did not improve performance compared to simpler default profiles. Overall, this study highlights the need for appropriate inputs, especially meteorological inputs, to dispersion models aimed at estimating near-road concentrations of TRAPs. It also highlights the potential for systematic biases that might affect analyses that use concentration predictions as exposure measures in health studies.

Uncertainty of chromatic dispersion estimation from transmitted waveforms in direct detection systems

Science.gov (United States)

Lach, Zbigniew T.

2017-08-01

A possibility is shown of a non-disruptive estimation of chromatic dispersion in a fiber of an intensity modulation communication line under work conditions. Uncertainty of the chromatic dispersion estimates is analyzed and quantified with the use of confidence intervals.

X-ray spectral models of Galactic bulge sources - the emission-line factor

International Nuclear Information System (INIS)

Vrtilek, S.D.; Swank, J.H.; Kallman, T.R.

1988-01-01

Current difficulties in finding unique and physically meaningful models for the X-ray spectra of Galactic bulge sources are exacerbated by the presence of strong, variable emission and absorption features that are not resolved by the instruments observing them. Nine Einstein solid state spectrometer (SSS) observations of five Galactic bulge sources are presented for which relatively high resolution objective grating spectrometer (OGS) data have been published. It is found that in every case the goodness of fit of simple models to SSS data is greatly improved by adding line features identified in the OGS that cannot be resolved by the SSS but nevertheless strongly influence the spectra observed by SSS. 32 references

Dispersal of potato cyst nematodes measured using historical and spatial statistical analyses.

Science.gov (United States)

Banks, N C; Hodda, M; Singh, S K; Matveeva, E M

2012-06-01

Rates and modes of dispersal of potato cyst nematodes (PCNs) were investigated. Analysis of records from eight countries suggested that PCNs spread a mean distance of 5.3 km/year radially from the site of first detection, and spread 212 km over ≈40 years before detection. Data from four countries with more detailed histories of invasion were analyzed further, using distance from first detection, distance from previous detection, distance from nearest detection, straight line distance, and road distance. Linear distance from first detection was significantly related to the time since the first detection. Estimated rate of spread was 5.7 km/year, and did not differ statistically between countries. Time between the first detection and estimated introduction date varied between 0 and 20 years, and differed among countries. Road distances from nearest and first detection were statistically significantly related to time, and gave slightly higher estimates for rate of spread of 6.0 and 7.9 km/year, respectively. These results indicate that the original site of introduction of PCNs may act as a source for subsequent spread and that this may occur at a relatively constant rate over time regardless of whether this distance is measured by road or by a straight line. The implications of this constant radial rate of dispersal for biosecurity and pest management are discussed, along with the effects of control strategies.

Development of X-ray photoelectron microscope with a compact X-ray source generated by line-focused laser irradiation

International Nuclear Information System (INIS)

Yamaguchi, N.; Takahashi, Z.; Nishimura, Y.; Watanabe, K.; Okamoto, Y.; Sakata, A.; Azuma, H.; Hara, T.

2005-01-01

A laboratory-sized X-ray photoelectron microscope was constructed using a compact X-ray source produced by line-focused laser irradiation. The system is a scanning type photoelectron microscope where X-ray beam is micro-focused via Schwarzschild optics. A compact laser-plasma X-ray source has been developed with a YAG laser, a line-focus lens assembly, an Al tape-target driver and a debris prevention system. The 13.1 nm X-ray was delivered along line plasma whose length was 0.6 or 11 mm with higher intensity than that from a point-focused source. The Schwarzschild optics having the designed demagnification of 224, which was coated with Mo/Si multilayers for 13.1 nm X-ray, was set on the beamline 1 m distant from the source. The electron energy analyser was a spherical capacitor analyser with the photoelectron image detection system that was suited for detection of vast photoelectrons excited by an X-ray pulse of ns-order duration. The spatial resolution less than 5 μm has been confirmed from the variation of As 3d electron intensity along the position of the GaAs sample coated with a photo-resist test pattern

High-frequency parameters of magnetic films showing magnetization dispersion

International Nuclear Information System (INIS)

Sidorenkov, V.V.; Zimin, A.B.; Kornev, Yu.V.

1988-01-01

Magnetization dispersion leads to skewed resonance curves shifted towards higher magnetizing fields, together with considerable reduction in the resonant absorption, while the FMR line width is considerably increased. These effects increase considerably with frequency, in contrast to films showing magnetic-anisotropy dispersion, where they decrease. It is concluded that there may be anomalies in the frequency dependence of the resonance parameters for polycrystalline magnetic films

Characterization of non point source pollutants and their dispersion ...

African Journals Online (AJOL)

EJIRO

landing site in Uganda. N. Banadda. Agricultural and Bio-Systems Engineering Department, Makerere University, P. O. Box 7062, Kampala, Uganda. E-mail: banadda@agric.mak.ac.ug. Fax: +256-414-53.16.41. Accepted 5 January, 2011. The aim of this research is to characterize non point pollutants and their dispersion in ...

Longitudinal dispersion of radioactive substances in Federal waterways

Energy Technology Data Exchange (ETDEWEB)

Krause, W.J. [Bundesanstalt fuer Gewaesserkunde (BfG), Koblenz (Germany); Speer, W.; Luellwitz, T.; Cremer, M.; Tolksdorf, W.

2007-08-15

In the context of radioactivity monitoring in German Federal Waterways (BWStr) by the Federal Institute of Hydrology (BfG) according to the Precautionary Radiation Protection Act (StrVG), the prediction of the dispersion of radioactive substances in water is one of the key tasks. The aim is the forecasting of the longitudinal dispersion of concentrations of soluble hazardous substances in flowing water. These predictions are based on the so-called dispersion tests with tritium as a tracer that the BfG has performed since 1980. Characteristic parameters like discharge-dependent flow velocities, dispersion and elimination constants related to emission sources or selected river sections are determined. They will serve as basis for a mathematical model to forecast discharge-dependent flow velocities, expected impact times, concentration maxima, and the duration of critical increases in concentrations. In the following, the results obtained till now from three investigation campaigns on the River Weser and its source rivers Werra and Fulda are described. (orig.)

Spatially Dispersed Employee Recovery

DEFF Research Database (Denmark)

Hvass, Kristian Anders; Torfadóttir, Embla

2014-01-01

Employee recovery addresses either employee well-being or management's practices in aiding employees in recovering themselves following a service failure. This paper surveys the cabin crew at a small, European, low-cost carrier and investigates employees' perceptions of management practices to aid...... personnel achieve service recovery. Employee recovery within service research often focuses on front-line employees that work in a fixed location, however a contribution to the field is made by investigating the recovery of spatially dispersed personnel, such as operational personnel in the transport sector......, who have a work place away from a fixed or central location and have minimal management contact. Results suggest that the support employees receive from management, such as recognition, information sharing, training, and strategic awareness are all important for spatially dispersed front...

Presence of amphibian chytrid fungus (Batrachochytrium dendrobatidis) in rainwater suggests aerial dispersal is possible

Science.gov (United States)

Kolby, Jonathan E.; Sara D. Ramirez,; Lee Berger,; Griffin, Dale W.; Merlijn Jocque,; Lee F. Skerratt,

2015-01-01

Abstract Global spread of the pathogenic amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) may involve dispersal mechanisms not previously explored. Weather systems accompanied by strong wind and rainfall have been known to assist the dispersal of microbes pathogenic to plants and animals, and we considered a similar phenomenon might occur with Bd. We investigated this concept by sampling rainwater from 20 precipitation events for the presence of Bd in Cusuco National Park, Honduras: a site where high Bd prevalence was previously detected in stream-associated amphibians. Quantitative PCR analysis confirmed the presence of Bd in rainwater in one (5 %) of the weather events sampled, although viability cannot be ascertained from molecular presence alone. The source of the Bd and distance that the contaminated rainwater traveled could not be determined; however, this collection site was located approximately 600 m from the nearest observed perennial river by straight-line aerial distance. Although our results suggest atmospheric Bd dispersal is uncommon and unpredictable, even occasional short-distance aerial transport could considerably expand the taxonomic diversity of amphibians vulnerable to exposure and at risk of decline, including terrestrial and arboreal species that are not associated with permanent water bodies.

Elevated source SF6-tracer dispersion experiments in the Copenhagen area. Preliminary results II

International Nuclear Information System (INIS)

Gryning, S.E.; Lyck, E.

1980-01-01

The results from 10 experiments, performed in neutral to unstable meteorological conditions, are reported from an ongoing series of elevated-source, urban-scale tracer dispersion experiments in the Copenhagen area. The tracer is released at a height of 115 m from the TV-tower in GLADSAXE, a suburb of Copenhagen, with tracer sampling units positioned at ground-level in 1 to 3 crosswind series, 2 to 6 km downwind of the tower. The lateral dispersion parameter, sigma(y), was estimated from the measured tracer concentration distribution and compared with values of sigma(y), computed by 1) methods based on wind variance measured during the experiments and 2) methods based on a stability classification of the atmospheric conditions. The wind-variance based methods proved superior in predicting the variation of sigma(y) compared with the stability based methods. Moreover, some of the former methods produced significantly biased estimates of sigma(y). The measured tracer concentration distributions were also crosswind integrated, chi(CWI). Estimates of chi(CWI) were computed using sigma (z) -values derived from the aforementioned computations assuming a Gaussian-type vertical tracer concentration distribution. A comparison is measured and calculated values of chi(CWI) showed no significant differences in the ability of the methods to predict the variation of chi(CWI). Only one method, the EPA, came out with a mean fractional error outside the range +-20% which constitutes the uncertainty in the absolute tracer concentration associated with the calibration of the gas chromatograph for tracer analysis

Influence of prey dispersion on territory and group size of African lions: a test of the resource dispersion hypothesis.

Science.gov (United States)

Valeix, Marion; Loveridge, Andrew J; MacDonald, David W

2012-11-01

Empirical tests of the resource dispersion hypothesis (RDH), a theory to explain group living based on resource heterogeneity, have been complicated by the fact that resource patch dispersion and richness have proved difficult to define and measure in natural systems. Here, we studied the ecology of African lions Panthera leo in Hwange National Park, Zimbabwe, where waterholes are prey hotspots, and where dispersion of water sources and abundance of prey at these water sources are quantifiable. We combined a 10-year data set from GPS-collared lions for which information of group composition was available concurrently with data for herbivore abundance at waterholes. The distance between two neighboring waterholes was a strong determinant of lion home range size, which provides strong support for the RDH prediction that territory size increases as resource patches are more dispersed in the landscape. The mean number of herbivore herds using a waterhole, a good proxy of patch richness, determined the maximum lion group biomass an area can support. This finding suggests that patch richness sets a maximum ceiling on lion group size. This study demonstrates that landscape ecology is a major driver of ranging behavior and suggests that aspects of resource dispersion limit group sizes.

Calculation of media temperatures for nuclear sources in geologic depositories by a finite-length line source superposition model (FLLSSM)

Energy Technology Data Exchange (ETDEWEB)

Kays, W M; Hossaini-Hashemi, F [Stanford Univ., Palo Alto, CA (USA). Dept. of Mechanical Engineering; Busch, J S [Kaiser Engineers, Oakland, CA (USA)

1982-02-01

A linearized transient thermal conduction model was developed to economically determine media temperatures in geologic repositories for nuclear wastes. Individual canisters containing either high-level waste or spent fuel assemblies are represented as finite-length line sources in a continuous medium. The combined effects of multiple canisters in a representative storage pattern can be established in the medium at selected point of interest by superposition of the temperature rises calculated for each canister. A mathematical solution of the calculation for each separate source is given in this article, permitting a slow hand calculation. The full report, ONWI-94, contains the details of the computer code FLLSSM and its use, yielding the total solution in one computer output.

In-town dispersion calculations with RIMPUFF and UDM

DEFF Research Database (Denmark)

Astrup, P.; Thykier-Nielsen, Søren; Mikkelsen, Torben

2005-01-01

and in depositions obtained with a code designed for dispersion of a release from a nuclear power plant, typically situated at a distance from densely inhabited areas, and a code specifically designed forpredicting dispersion from sources inside urban areas. The codes applied are the RIMPUFF code, RIsø Mesoscale...

Non-Linear Transmission Line (NLTL) Microwave Source Lecture Notes the United States Particle Accelerator School

Energy Technology Data Exchange (ETDEWEB)

Russell, Steven J. [Los Alamos National Laboratory; Carlsten, Bruce E. [Los Alamos National Laboratory

2012-06-26

We will quickly go through the history of the non-linear transmission lines (NLTLs). We will describe how they work, how they are modeled and how they are designed. Note that the field of high power, NLTL microwave sources is still under development, so this is just a snap shot of their current state. Topics discussed are: (1) Introduction to solitons and the KdV equation; (2) The lumped element non-linear transmission line; (3) Solution of the KdV equation; (4) Non-linear transmission lines at microwave frequencies; (5) Numerical methods for NLTL analysis; (6) Unipolar versus bipolar input; (7) High power NLTL pioneers; (8) Resistive versus reactive load; (9) Non-lineaer dielectrics; and (10) Effect of losses.

FIRST Bent-Double Radio Sources: Tracers of High-Redshift Clusters

International Nuclear Information System (INIS)

Blanton, E. L.; Gregg, M. D.; Helfand, D. J.; Becker, R. H.; White, R. L.

2000-01-01

Bent-double radio sources can act as tracers for clusters of galaxies. We present imaging and spectroscopic observations of the environments surrounding 10 of these sources (most of them wide-angle tails [WATs]) selected from the VLA FIRST survey. Our results reveal a previously unknown cluster associated with eight of the radio sources with redshifts in the range 0.33< z<0.85; furthermore, we cannot rule out that the other two bent doubles may be associated with clusters at higher redshift. Richness measurements indicate that these clusters are typical of the majority of those found in the Abell catalog, with a range of Abell richness classes from 0 to 2. The line-of-sight velocity dispersions are very different from cluster to cluster, ranging from approximately 300 to 1100 km s-1. At the upper end of these intervals, we may be sampling some of the highest redshift massive clusters known. Alternatively, the large velocity dispersions measured in some of the clusters may indicate that they are merging systems with significant substructure, consistent with recent ideas concerning WAT formation (Burns et al.). (c) 2000 The American Astronomical Society

Numerical simulation on pollutant dispersion from vehicle exhaust in street configurations.

Science.gov (United States)

Yassin, Mohamed F; Kellnerová, R; Janour, Z

2009-09-01

The impact of the street configurations on pollutants dispersion from vehicles exhausts within urban canyons was numerically investigated using a computational fluid dynamics (CFD) model. Three-dimensional flow and dispersion of gaseous pollutants were modeled using standard kappa - epsilon turbulence model, which was numerically solved based on Reynolds-averaged Navier-Stokes equations by the commercial CFD code FLUENT. The concentration fields in the urban canyons were examined in three cases of street configurations: (1) a regular-shaped intersection, (2) a T-shaped intersection and (3) a Skew-shaped crossing intersection. Vehicle emissions were simulated as double line sources along the street. The numerical model was validated against wind tunnel results in order to optimize the turbulence model. Numerical predictions agreed reasonably well with wind tunnel results. The results obtained indicate that the mean horizontal velocity was very small in the center near the lower region of street canyon. The lowest turbulent kinetic energy was found at the separation and reattachment points associated with the corner of the down part of the upwind and downwind buildings in the street canyon. The pollutant concentration at the upwind side in the regular-shaped street intersection was higher than that in the T-shaped and Skew-shaped street intersections. Moreover, the results reveal that the street intersections are important factors to predict the flow patterns and pollutant dispersion in street canyon.

On beam shaping of the field radiated by a line source coupled to finite or infinite photonic crystals.

Science.gov (United States)

Ceccuzzi, Silvio; Jandieri, Vakhtang; Baccarelli, Paolo; Ponti, Cristina; Schettini, Giuseppe

2016-04-01

Comparison of the beam-shaping effect of a field radiated by a line source, when an ideal infinite structure constituted by two photonic crystals and an actual finite one are considered, has been carried out by means of two different methods. The lattice sums technique combined with the generalized reflection matrix method is used to rigorously investigate the radiation from the infinite photonic crystals, whereas radiation from crystals composed of a finite number of rods along the layers is analyzed using the cylindrical-wave approach. A directive radiation is observed with the line source embedded in the structure. With an increased separation distance between the crystals, a significant edge diffraction appears that provides the main radiation mechanism in the finite layout. Suitable absorbers are implemented to reduce the above-mentioned diffraction and the reflections at the boundaries, thus obtaining good agreement between radiation patterns of a localized line source coupled to finite and infinite photonic crystals, when the number of periods of the finite structure is properly chosen.

N III Bowen Lines and Fluorescence Mechanism in the Symbiotic Star AG Peg

Science.gov (United States)

Hyung, Siek; Lee, Seong-Jae; Lee, Kang Hwan

2018-03-01

We have investigated the intensities and full width at half maximum (FWHM) of the high dispersion spectroscopic N III emission lines of AG Peg, observed with the Hamilton Echelle Spectrograph (HES) in three different epochs at Mt. Hamilton's Lick Observatory. The earlier theoretical Bowen line study assumed the continuum fluorescence effect, presenting a large discrepancy with the present data. Hence, we analyzed the observed N III lines assuming line fluorescence as the only suitable source: (1) The O III and N III resonance line profiles near λ 374 were decomposed, using the Gaussian function, and the contributions from various O III line components were determined. (2) Based on the theoretical resonant N III intensities, the expected N III Bowen intensities were obtained to fit the observed values. Our study shows that the incoming line photon number ratio must be considered to balance at each N III Bowen line level in the ultraviolet radiation according to the observed lines in the optical zone. We also found that the average FWHM of the N III Bowen lines was about 5 km·s-1 greater than that of the O III Bowen lines, perhaps due to the inherently different kinematic characteristics of their emission zones.

Wind tunnel simulation of air pollution dispersion in a street canyon.

Science.gov (United States)

Civis, Svatopluk; Strizík, Michal; Janour, Zbynek; Holpuch, Jan; Zelinger, Zdenek

2002-01-01

Physical simulation was used to study pollution dispersion in a street canyon. The street canyon model was designed to study the effect of measuring flow and concentration fields. A method of C02-laser photoacoustic spectrometry was applied for detection of trace concentration of gas pollution. The advantage of this method is its high sensitivity and broad dynamic range, permitting monitoring of concentrations from trace to saturation values. Application of this method enabled us to propose a simple model based on line permeation pollutant source, developed on the principle of concentration standards, to ensure high precision and homogeneity of the concentration flow. Spatial measurement of the concentration distribution inside the street canyon was performed on the model with reference velocity of 1.5 m/s.

Air Dispersion Modeling for Building 3026C/D Demolition

Energy Technology Data Exchange (ETDEWEB)

Ward, Richard C [ORNL; Sjoreen, Andrea L [ORNL; Eckerman, Keith F [ORNL

2010-06-01

This report presents estimates of dispersion coefficients and effective dose for potential air dispersion scenarios of uncontrolled releases from Oak Ridge National Laboratory (ORNL) buildings 3026C, 3026D, and 3140 prior to or during the demolition of the 3026 Complex. The Environmental Protection Agency (EPA) AERMOD system1-6 was used to compute these estimates. AERMOD stands for AERMIC Model, where AERMIC is the American Meteorological Society-EPA Regulatory Model Improvement Committee. Five source locations (three in building 3026D and one each in building 3026C and the filter house 3140) and associated source characteristics were determined with the customer. In addition, the area of study was determined and building footprints and intake locations of air-handling systems were obtained. In addition to the air intakes, receptor sites consisting of ground level locations on four polar grids (50 m, 100 m, 200 m, and 500 m) and two intersecting lines of points (50 m separation), corresponding to sidewalks along Central Avenue and Fifth Street. Three years of meteorological data (2006 2008) were used each consisting of three datasets: 1) National Weather Service data; 2) upper air data for the Knoxville-Oak Ridge area; and 3) local weather data from Tower C (10 m, 30 m and 100 m) on the ORNL reservation. Annual average air concentration, highest 1 h average and highest 3 h average air concentrations were computed using AERMOD for the five source locations for the three years of meteorological data. The highest 1 h average air concentrations were converted to dispersion coefficients to characterize the atmospheric dispersion as the customer was interested in the most significant response and the highest 1 h average data reflects the best time-averaged values available from the AERMOD code. Results are presented in tabular and graphical form. The results for dose were obtained using radionuclide activities for each of the buildings provided by the customer.7

Resonance ionization laser ion sources for on-line isotope separators (invited)

International Nuclear Information System (INIS)

Marsh, B. A.

2014-01-01

A Resonance Ionization Laser Ion Source (RILIS) is today considered an essential component of the majority of Isotope Separator On Line (ISOL) facilities; there are seven laser ion sources currently operational at ISOL facilities worldwide and several more are under development. The ionization mechanism is a highly element selective multi-step resonance photo-absorption process that requires a specifically tailored laser configuration for each chemical element. For some isotopes, isomer selective ionization may even be achieved by exploiting the differences in hyperfine structures of an atomic transition for different nuclear spin states. For many radioactive ion beam experiments, laser resonance ionization is the only means of achieving an acceptable level of beam purity without compromising isotope yield. Furthermore, by performing element selection at the location of the ion source, the propagation of unwanted radioactivity downstream of the target assembly is reduced. Whilst advances in laser technology have improved the performance and reliability of laser ion sources and broadened the range of suitable commercially available laser systems, many recent developments have focused rather on the laser/atom interaction region in the quest for increased selectivity and/or improved spectral resolution. Much of the progress in this area has been achieved by decoupling the laser ionization from competing ionization processes through the use of a laser/atom interaction region that is physically separated from the target chamber. A new application of gas catcher laser ion source technology promises to expand the capabilities of projectile fragmentation facilities through the conversion of otherwise discarded reaction fragments into high-purity low-energy ion beams. A summary of recent RILIS developments and the current status of laser ion sources worldwide is presented

Geochemical and Pb isotopic evidence for sources and dispersal of metal contamination in stream sediments from the mining and smelting district of Pribram, Czech Republic

International Nuclear Information System (INIS)

Ettler, Vojtech; Mihaljevic, Martin; Sebek, Ondrej; Molek, Michael; Grygar, Tomas; Zeman, Josef

2006-01-01

Stream sediments from the mining and smelting district of Pribram, Czech Republic, were studied to determine the degree, sources and dispersal of metal contamination using a combination of bulk metal and mineralogical determinations, sequential extractions and Pb isotopic analyses. The highest metal concentrations were found 3-4 km downstream from the main polymetallic mining site (9800 mg Pb kg -1 , 26 039 mg Zn kg -1 , 316.4 mg Cd kg -1 , 256.9 mg Cu kg -1 ). The calculated enrichment factors (EFs) confirmed the extreme degree of contamination by Pb, Zn and Cd (EF > 40). Lead, Zn and Cd are bound mainly to Fe oxides and hydroxides. In the most contaminated samples Pb is also present as Pb carbonates and litharge (PbO). Lead isotopic analysis indicates that the predominant source of stream sediment contamination is historic Pb-Ag mining and primary Pb smelting ( 206 Pb/ 207 Pb = 1.16), while the role of secondary smelting (car battery processing) is negligible. - Pb isotopes properly complete traditional investigations of metal sources and dispersal in contaminated stream sediments

Atmospheric dispersion and inverse modelling for the reconstruction of accidental sources of pollutants

International Nuclear Information System (INIS)

Winiarek, Victor

2014-01-01

Uncontrolled releases of pollutant in the atmosphere may be the consequence of various situations: accidents, for instance leaks or explosions in an industrial plant, or terrorist attacks such as biological bombs, especially in urban areas. In the event of such situations, authorities' objectives are various: predict the contaminated zones to apply first countermeasures such as evacuation of concerned population; determine the source location; assess the long-term polluted areas, for instance by deposition of persistent pollutants in the soil. To achieve these objectives, numerical models can be used to model the atmospheric dispersion of pollutants. We will first present the different processes that govern the transport of pollutants in the atmosphere, then the different numerical models that are commonly used in this context. The choice between these models mainly depends of the scale and the details one seeks to take into account. We will then present several inverse modeling methods to estimate the emission as well as statistical methods to estimate prior errors, to which the inversion is very sensitive. Several case studies are presented, using synthetic data as well as real data such as the estimation of source terms from the Fukushima accident in March 2011. From our results, we estimate the Cesium-137 emission to be between 12 and 19 PBq with a standard deviation between 15 and 65% and the Iodine-131 emission to be between 190 and 380 PBq with a standard deviation between 5 and 10%. Concerning the localization of an unknown source of pollutant, two strategies can be considered. On one hand parametric methods use a limited number of parameters to characterize the source term to be reconstructed. To do so, strong assumptions are made on the nature of the source. The inverse problem is hence to estimate these parameters. On the other hand nonparametric methods attempt to reconstruct a full emission field. Several parametric and nonparametric methods are

Kinetics of Low Temperature Polyester Dyeing with High Molecular Weight Disperse Dyes by Solvent Microemulsion and AgroSourced Auxiliaries

OpenAIRE

Shahram Radei; F. Javier Carrión-Fité; Mònica Ardanuy; José María Canal

2018-01-01

This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin) using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of n-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100...

Multispectral Analysis of Surface Wave (MASW) Analysis of Near-Surface Structure at Brady Hot Springs from Active Source and Ambient Noise Using a 8700-meter Distributed Acoustic Sensing (DAS) Array

Science.gov (United States)

Wang, H. F.; Lord, N. E.; Zeng, X.; Fratta, D.; Feigl, K. L.; Team, P.

2016-12-01

The Porotomo research team deployed 8700-meters of Distributed Acoustic Sensing (DAS) cable in a shallow trench on the surface and 400 meters down a borehole at Brady Hot Springs, Nevada in March 2016. The goal of the experiment was to detect changes in geophysical properties associated with hydrologic changes. The DAS cable occupied a natural laboratory of 1500-by-500-by-400-meters overlying a commercial, geothermal field operated by Ormat Technologies. The DAS cable was laid out in three parallel zig-zag lines with line segments approximately 120-meters in length. A large Vibroseis truck (T-Rex) provided the seismic source with a sweep frequency between 5 and 80 Hz over 20 seconds. Over the 15 days of the experiment, the Vibroseis truck re-occupied approximately 250 locations outside and within the array days while changes were made in water reinjection from the power plant into wells in the field. At each source location, one vertical and two orthogonal horizontal modes were excited. Dispersion curves were constructed using MASW and a Vibroseis source location approximately in line with each DAS cable segment or from ambient noise correlation functions. Representative fence diagrams of S-wave profiles were constructed by inverting the dispersion curves obtained for several different line segments.

Fluctuation Scaling, Calibration of Dispersion, and Detection of Differences.

Science.gov (United States)

Holland, Rianne; Rebmann, Roman; Williams, Craig; Hanley, Quentin S

2017-11-07

Fluctuation scaling describes the relationship between the mean and standard deviation of a set of measurements. An example is Horwitz scaling, which has been reported from interlaboratory studies. Horwitz and similar studies have reported simple exponential and segmented scaling laws with exponents (α) typically between 0.85 (Horwitz) and 1 when not operating near a detection limit. When approaching a detection limit, the exponents change and approach an apparently Gaussian (α = 0) model. This behavior is often presented as a property of interlaboratory studies, which makes controlled replication to understand the behavior costly to perform. To assess the contribution of instrumentation to larger scale fluctuation scaling, we measured the behavior of two inductively coupled plasma atomic emission spectrometry (ICP-AES) systems, in two laboratories measuring thulium using two emission lines. The standard deviation universally increased with the uncalibrated signal, indicating the system was heteroscedastic. The response from all lines and both instruments was consistent with a single exponential dispersion model having parameters α = 1.09 and β = 0.0035. No evidence of Horwitz scaling was found, and there was no evidence of Poisson noise limiting behavior. The "Gaussian" component was a consequence of background subtraction for all lines and both instruments. The observation of a simple exponential dispersion model in the data allows for the definition of a difference detection limit (DDL) with universal applicability to systems following known dispersion. The DDL is the minimum separation between two points along a dispersion model required to claim they are different according to a particular statistical test. The DDL scales transparently with the mean and works at any location in a response function.

Dispersal kernel estimation: A comparison of empirical and modelled particle dispersion in a coastal marine system

Science.gov (United States)

Hrycik, Janelle M.; Chassé, Joël; Ruddick, Barry R.; Taggart, Christopher T.

2013-11-01

Early life-stage dispersal influences recruitment and is of significance in explaining the distribution and connectivity of marine species. Motivations for quantifying dispersal range from biodiversity conservation to the design of marine reserves and the mitigation of species invasions. Here we compare estimates of real particle dispersion in a coastal marine environment with similar estimates provided by hydrodynamic modelling. We do so by using a system of magnetically attractive particles (MAPs) and a magnetic-collector array that provides measures of Lagrangian dispersion based on the time-integration of MAPs dispersing through the array. MAPs released as a point source in a coastal marine location dispersed through the collector array over a 5-7 d period. A virtual release and observed (real-time) environmental conditions were used in a high-resolution three-dimensional hydrodynamic model to estimate the dispersal of virtual particles (VPs). The number of MAPs captured throughout the collector array and the number of VPs that passed through each corresponding model location were enumerated and compared. Although VP dispersal reflected several aspects of the observed MAP dispersal, the comparisons demonstrated model sensitivity to the small-scale (random-walk) particle diffusivity parameter (Kp). The one-dimensional dispersal kernel for the MAPs had an e-folding scale estimate in the range of 5.19-11.44 km, while those from the model simulations were comparable at 1.89-6.52 km, and also demonstrated sensitivity to Kp. Variations among comparisons are related to the value of Kp used in modelling and are postulated to be related to MAP losses from the water column and (or) shear dispersion acting on the MAPs; a process that is constrained in the model. Our demonstration indicates a promising new way of 1) quantitatively and empirically estimating the dispersal kernel in aquatic systems, and 2) quantitatively assessing and (or) improving regional hydrodynamic

MEMS-based transmission lines for microwave applications

Science.gov (United States)

Wu, Qun; Fu, Jiahui; Gu, Xuemai; Shi, Huajuan; Lee, Jongchul

2003-04-01

This paper mainly presents a briefly review for recent progress in MEMS-based transmission lines for use in microwave and millimeterwave range. MEMS-based transmission lines including different transmission line structure such as membrane-supported microstrip line microstrip line, coplanar microshield transmission line, LIGA micromachined planar transmission line, micromachined waveguides and coplanar waveguide are discussed. MEMS-based transmission lines are characterized by low propagation loss, wide operation frequency band, low dispersion and high quality factor, in addition, the fabrication is compatible with traditional processing of integrated circuits (IC"s). The emergence of MEMS-based transmission lines provided a solution for miniaturizing microwave system and monolithic microwave integrated circuits.

Development of an on-line high-temperature ion source for neutron-rich fission products at TRIGA-SPEC

Energy Technology Data Exchange (ETDEWEB)

Renisch, Dennis [Institut fuer Kernchemie, Johannes Gutenberg-Universitaet Mainz (Germany); Collaboration: TRIGA-SPEC-Collaboration

2012-07-01

The TRIGA-SPEC experiment at the TRIGA Mainz research reactor aims to determine ground-state properties of exotic nuclides. It includes the Penning-trap mass spectrometer TRIGA-TRAP and the collinear laser spectroscopy setup TRIGA-LASER. Nuclides of interest are produced in the neutron-induced fission of suitable actinide isotopes, thermalized in a gas-filled volume and transported to an on-line ion source with a gas-jet. The ion source being constructed has two operation modes: a high-temperature surface ionization mode and a hollow cathode plasma mode. It is expected that the surface mode will yield a high ionization efficiency for certain elements, in the order of at least several percent, whereas the plasma mode has the advantage, that more elements can be ionized but with lower efficiency compared to the surface ionization mode. The current status of the TRIGA-SPEC experiments and the present performance of the on-line ion source are presented.

The in-focus variable line spacing plane grating monochromator

International Nuclear Information System (INIS)

Reininger, R.

2011-01-01

The in-focus variable line spacing plane grating monochromator is based on only two plane optical elements, a variable line spacing plane grating and a plane pre-mirror that illuminates the grating at the angle of incidence that will focus the required photon energy. A high throughput beamline requires only a third optical element after the exit slit, an aberration corrected elliptical toroid. Since plane elements can be manufactured with the smallest figure errors, this monochromator design can achieve very high resolving power. Furthermore, this optical design can correct the deformations induced by the heat load on the optics along the dispersion plane. This should allow obtaining a resolution of 10 meV at 1 keV with currently achievable figure errors on plane optics. The position of the photon source when an insertion device center is not located at the center of the straight section, a common occurrence in new insertion device beamlines, is investigated.

Atmospheric tracer experiments for regional dispersion studies

International Nuclear Information System (INIS)

Heffter, J.L.; Ferber, G.J.

1980-01-01

Tracer experiments are being conducted to verify atmospheric transport and dispersion calculations at distances from tens to hundreds of km from pollutant sources. In one study, a 2 1/2 year sampling program has been carried out at 13 sites located 30 to 140 km from a source of 85 Kr at the Savannah River Plant in South Carolina. Average weekly concentrations as well as twice-daily concentrations were obtained. Sampling data and meteorological data, including surface, tower, and rawinsonde observations are available on magnetic tape for model verification studies. Some verification results for the Air Resources Laboratories Atmospheric Transort and Dispersion Model (ARL-ATAD) are shown for averaging periods from one week to two years

Diffraction of an impulsive line source with wake

International Nuclear Information System (INIS)

Ayub, M; Naeem, A; Nawaz, Rab

2010-01-01

The problem of diffraction due to an impulse line source by an absorbing half-plane with wake using Myres' impedance condition (Myers 1980 J. Sound Vib. 71 429-34) in the presence of a subsonic fluid flow is studied. The time dependence of the field requires a temporal Fourier transform in addition to the spatial Fourier transform. The solution of the problem in the presence of wake is obtained by using Greens' function method, Fourier transform, the Wiener-Hopf technique and the modified stationary phase method. Expressions for the total far field for the trailing edge (wake present) situation are given. It is observed that the field produced by the Kutta-Joukowski condition will be substantially in excess of the field when this condition is ignored. Finally, a simple procedure is devised to calculate the inverse temporal Fourier transform. The solution for the leading edge situation can be obtained if the wake, and consequently a Kutta-Joukowski edge condition, is ignored. This can also be seen from the numerical results.

Operational evaluation of the RLINE dispersion model for studies of traffic-related air pollutants

Science.gov (United States)

Milando, Chad W.; Batterman, Stuart A.

2018-06-01

Exposure to traffic-related air pollutants (TRAP) remains a key public health issue, and improved exposure measures are needed to support health impact and epidemiologic studies and inform regulatory responses. The recently developed Research LINE source model (RLINE), a Gaussian line source dispersion model, has been used in several epidemiologic studies of TRAP exposure, but evaluations of RLINE's performance in such applications have been limited. This study provides an operational evaluation of RLINE in which predictions of NOx, CO and PM2.5 are compared to observations at air quality monitoring stations located near high traffic roads in Detroit, MI. For CO and NOx, model performance was best at sites close to major roads, during downwind conditions, during weekdays, and during certain seasons. For PM2.5, the ability to discern local and particularly the traffic-related portion was limited, a result of high background levels, the sparseness of the monitoring network, and large uncertainties for certain processes (e.g., formation of secondary aerosols) and non-mobile sources (e.g., area, fugitive). Overall, RLINE's performance in near-road environments suggests its usefulness for estimating spatially- and temporally-resolved exposures. The study highlights considerations relevant to health impact and epidemiologic applications, including the importance of selecting appropriate pollutants, using appropriate monitoring approaches, considering prevailing wind directions during study design, and accounting for uncertainty.

Validation of a two-dimensional pollutant dispersion model in an isolated street canyon

Energy Technology Data Exchange (ETDEWEB)

Chan, T.L.; Dong, G.; Leung, C.W.; Cheung, C.S. [The Hong Kong Polytechnic University, Kowloon (Hong Kong). Research Centre for Combustion and Pollution Control, Department of Mechanical Engineering; Hung, W.T. [The Hong Kong Polytechnic University, Kowloon (Hong Kong). Department of Civil and Structural Engineering

2002-07-01

A two-dimensional numerical model based on Reynolds-averaged Navier-Stokes equations coupled with a series of standard, Renormalization Group (RNG) and realizable k-{epsilon} turbulence models was developed to simulate the fluid-flow development and pollutant dispersion within an isolated street canyon using the FLUENT code. In the present study, the validation of the numerical model was evaluated using an extensive experimental database obtained from the atmospheric boundary layer wind tunnel at the Meteorological Institute of Hamburg University, Germany (J. Wind Eng. Ind. Aerodyn. 62 (1996) 37). Among the studied turbulence models, the RNG k-{epsilon} turbulence model was found to be the most optimum turbulence model coupled with the two-dimensional street canyon model developed in the present study. Both the calculated and measured dimensionless pollutant concentrations have been shown to be less dependent on the variation of wind speed and source strength conditions for the studied street canyon aspect ratio of the B/H=1 case. However, the street canyon configuration has significant influence on the pollutant dispersion. The wider street and lower height of the buildings are favorable to pollutant dilution within the street canyon. The fluid-flow development has demonstrated that the rotative vortex or vortices generated within the urban street canyon can transport the pollutants from a line source to the wall surfaces of the buildings. (author)

Practical Model for First Hyperpolarizability Dispersion Accounting for Both Homogeneous and Inhomogeneous Broadening Effects.

Science.gov (United States)

Campo, Jochen; Wenseleers, Wim; Hales, Joel M; Makarov, Nikolay S; Perry, Joseph W

2012-08-16

A practical yet accurate dispersion model for the molecular first hyperpolarizability β is presented, incorporating both homogeneous and inhomogeneous line broadening because these affect the β dispersion differently, even if they are indistinguishable in linear absorption. Consequently, combining the absorption spectrum with one free shape-determining parameter Ginhom, the inhomogeneous line width, turns out to be necessary and sufficient to obtain a reliable description of the β dispersion, requiring no information on the homogeneous (including vibronic) and inhomogeneous line broadening mechanisms involved, providing an ideal model for practical use in extrapolating experimental nonlinear optical (NLO) data. The model is applied to the efficient NLO chromophore picolinium quinodimethane, yielding an excellent fit of the two-photon resonant wavelength-dependent data and a dependable static value β0 = 316 × 10(-30) esu. Furthermore, we show that including a second electronic excited state in the model does yield an improved description of the NLO data at shorter wavelengths but has only limited influence on β0.

Line x-ray source for diffraction enhanced imaging in clinical and industrial applications

Science.gov (United States)

Wang, Xiaoqin

Mammography is one type of imaging modalities that uses a low-dose x-ray or other radiation sources for examination of breasts. It plays a central role in early detection of breast cancers. The material similarity of tumor-cell and health cell, breast implants surgery and other factors, make the breast cancers hard to visualize and detect. Diffraction enhanced imaging (DEI), first proposed and investigated by D. Chapman is a new x-ray radiographic imaging modality using monochromatic x-rays from a synchrotron source, which produced images of thick absorbing objects that are almost completely free of scatter. It shows dramatically improved contrast over standard imaging when applied to the same phantom. The contrast is based not only on attenuation but also on the refraction and diffraction properties of the sample. This imaging method may improve image quality of mammography, other medical applications, industrial radiography for non-destructive testing and x-ray computed tomography. However, the size, and cost, of a synchrotron source limits the application of the new modality to be applicable at clinical levels. This research investigates the feasibility of a designed line x-ray source to produce intensity compatible to synchrotron sources. It is composed of a 2-cm in length tungsten filament, installed on a carbon steel filament cup (backing plate), as the cathode and a stationary oxygen-free copper anode with molybdenum coating on the front surface serves as the target. Characteristic properties of the line x-ray source were computationally studied and the prototype was experimentally investigated. SIMIION code was used to computationally study the electron trajectories emanating from the filament towards the molybdenum target. A Faraday cup on the prototype device, proof-of-principle, was used to measure the distribution of electrons on the target, which compares favorably to computational results. The intensities of characteristic x-ray for molybdenum

Materials research and beam line operation utilizing NSLS [National Synchrotron Light Source]: Progress report

International Nuclear Information System (INIS)

Liedl, G.L.

1987-10-01

MATRIX is a group of scientists who have common interests in utilizing x-ray synchrotron radiation for materials research. This group has developed a specialized beam line (X-18A) for x-ray scattering studies at the National Synchrotron Light Source (NSLS). The beam line was designed to optimize experimental conditions for diffuse scattering and surface/interface studies. An extension of diffuse scattering to provide better quantitative data has been shown as well as a unique application to the solution of the phase problem. In the x-ray surface scattering area the first reported experiment to illustrate the capabilities for studying monolayers on water was performed. Current beam line upgrade projects are also described. In addition to a change to a UHV system and improvements dictated by operational experience, two new systems are described, a unique small angle scattering chamber (SAXS) for dynamic studies of nucleation and growth and a surface scattering chamber. 5 figs

Synchrotron radiation as a source for quantitative XPS: advantages and consequences

International Nuclear Information System (INIS)

Rosseel, T.M.; Carlson, T.A.; Negri, R.E.; Beall, C.E.; Taylor, J.W.

1986-01-01

Synchrotron radiation (SR) has a variety of properties which make it an attractive source for quantitative x-ray photoelectron spectroscopy (XPS). Among the most significant are high intensity and tunability. In addition, the intensity of the dispersed radiation is comparable to laboratory line sources. Synchrotron radiation is also a clean source, i.e., it will not contaminate the sample, because it operates under ultra-high vacuum conditions. We have used these properties to demonstrate the advantages of SR as a source for quantitative XPS. We have also found several consequences associated with this source which can either limit its use or provide unique opportunities for analysis and research. Using the tunability of SR, we have measured the energy dependence of the 3p photoionization cross sections of Ti, Cr, and Mn from 50 to 150 eV above threshold at the University of Wisconsin's Tantalus electron-storage ring

The use of nonlinear regression analysis for integrating pollutant concentration measurements with atmospheric dispersion modeling for source term estimation

International Nuclear Information System (INIS)

Edwards, L.L.; Freis, R.P.; Peters, L.G.; Gudiksen, P.H.; Pitovranov, S.E.

1993-01-01

The accuracy associated with assessing the environmental consequences of an accidental release of radioactivity is highly dependent on the knowledge of the source term characteristics, which are generally poorly known. The development of an automated numerical technique that integrates the radiological measurements with atmospheric dispersion modeling for more accurate source term estimation is reported. Often, this process of parameter estimation is performed by an emergency response assessor, who takes an intelligent first guess at the model parameters, then, comparing the model results with whatever measurements are available, makes an intuitive, informed next guess of the model parameters. This process may be repeated any number of times until the assessor feels that the model results are reasonable in terms of the measured observations. A new approach, based on a nonlinear least-squares regression scheme coupled with the existing Atmospheric Release Advisory Capability three-dimensional atmospheric dispersion models, is to supplement the assessor's intuition with automated mathematical methods that do not significantly increase the response time of the existing predictive models. The viability of the approach is evaluated by estimation of the known SF 6 tracer release rates associated with the Mesoscale Atmospheric Transport Studies tracer experiments conducted at the Savannah River Laboratory during 1983. These 19 experiments resulted in 14 successful, separate tracer releases with sampling of the tracer plumes along the cross-plume arc situated ∼30 km from the release site

Analysis of Nonlinear Dispersion of a Pollutant Ejected by an External Source into a Channel Flow

Directory of Open Access Journals (Sweden)

T. Chinyoka

2010-01-01

Full Text Available This paper focuses on the transient analysis of nonlinear dispersion of a pollutant ejected by an external source into a laminar flow of an incompressible fluid in a channel. The influence of density variation with pollutant concentration is approximated according to the Boussinesq approximation, and the nonlinear governing equations of momentum and pollutant concentration are obtained. The problem is solved numerically using a semi-implicit finite difference method. Solutions are presented in graphical form and given in terms of fluid velocity, pollutant concentration, skin friction, and wall mass transfer rate for various parametric values. The model can be a useful tool for understanding the polluting situations of an improper discharge incident and evaluating the effects of decontaminating measures for the water body.

Chromatic dispersion effects in ultra-low coherence interferometry

Energy Technology Data Exchange (ETDEWEB)

Lychagov, V V; Ryabukho, V P [N.G.Chernyshevsky Saratov State University (Russian Federation)

2015-06-30

We consider the properties of an interference signal shift from zero-path-difference position in the presence of an uncompensated dispersive layer in one of the interferometer arms. It is experimentally shown that in using an ultra-low coherence light source, the formation of the interference signal is also determined by the group velocity dispersion, which results in a nonlinear dependence of the position of the interference signal on the geometrical thickness of the dispersive layer. The discrepancy in the dispersive layer and compensator refractive indices in the third decimal place is experimentally shown to lead to an interference signal shift that is an order of magnitude greater than the pulse width. (interferometry)

An emission-line model for AM Herculis systems

International Nuclear Information System (INIS)

Ferrario, L.; Tuohy, I.R.; Wickramasinghe, D.T.; Australian National Univ., Canberra)

1989-01-01

The optical spectra of the AM Herculis binaries are characterized by extremely complex emission lines whose profiles can be resolved into at least three components which are formed in different regions of the accretion stream leading from the companion star toward the magnetic white dwarf. A theoretical model is presented for the radial velocity and velocity dispersion of the broad emission line component assuming that it originates mainly in the gas which is diverted out of the orbital plane and funneled onto the white dwarf surface along magnetic field lines. The model is used to locate the line-forming region in three AM Her variables: E1405-451, CW 1103+254, and EXO 033319-2554.2, using as constraints the radial velocity and velocity dispersion data. The analyses of these systems show that the material is threaded by the magnetic field in a very azimuthally extended coupling region located 0.5-0.75 of the way between the white dwarf and the inner Lagrange point. 36 refs

A New Diagnostic Diagram of Ionization Sources for High-redshift Emission Line Galaxies

Science.gov (United States)

Zhang, Kai; Hao, Lei

2018-04-01

We propose a new diagram, the kinematics–excitation (KEx) diagram, which uses the [O III] λ5007/Hβ line ratio and the [O III] λ5007 emission line width (σ [O III]) to diagnose the ionization source and physical properties of active galactic nuclei (AGNs) and star-forming galaxies (SFGs). The KEx diagram is a suitable tool to classify emission line galaxies at intermediate redshift because it uses only the [O III] λ5007 and Hβ emission lines. We use the main galaxy sample of SDSS DR7 and the Baldwin‑Phillips‑Terlevich (BPT) diagnostic to calibrate the diagram at low redshift. The diagram can be divided into three regions: the KEx-AGN region, which consists mainly of pure AGNs, the KEx-composite region, which is dominated by composite galaxies, and the KEx-SFG region, which contains mostly SFGs. LINERs strongly overlap with the composite and AGN regions. AGNs are separated from SFGs in this diagram mainly because they preferentially reside in luminous and massive galaxies and have higher [O III]/Hβ than SFGs. The separation between AGNs and SFGs is even cleaner thanks to the additional 0.15/0.12 dex offset in σ [O III] at fixed luminosity/stellar mass. We apply the KEx diagram to 7866 galaxies at 0.3 Survey, and compare it to an independent X-ray classification scheme using Chandra observations. X-ray AGNs are mostly located in the KEx-AGN region, while X-ray SFGs are mostly located in the KEx-SFG region. Almost all Type 1 AGNs lie in the KEx-AGN region. These tests support the reliability of this classification diagram for emission line galaxies at intermediate redshift. At z ∼ 2, the demarcation line between SFGs and AGNs is shifted by ∼0.3 dex toward higher values of σ [O III] due to evolution effects.

Dispersal patterns of red foxes relative to population density

Science.gov (United States)

Allen, Stephen H.; Sargeant, Alan B.

1993-01-01

Factors affecting red fox (Vulpes vulpes) dispersal patterns are poorly understood but warranted investigation because of the role of dispersal in rebuilding depleted populations and transmission of diseases. We examined dispersal patterns of red foxes in North Dakota based on recoveries of 363 of 854 foxes tagged as pups and relative to fox density. Foxes were recovered up to 8.6 years after tagging; 79% were trapped or shot. Straight-line distances between tagging and recovery locations ranged from 0 to 302 km. Mean recovery distances increased with age and were greater for males than females, but longest individual recovery distances were by females. Dispersal distances were not related to population density for males (P = 0.36) or females (P = 0.96). The proportion of males recovered that dispersed was inversely related to population density (r = -0.94; n = 5; P = 0.02), but not the proportion of females (r = -0.49; n = 5; P = 0.40). Dispersal directions were not uniform for either males (P = 0.003) or females (P = 0.006); littermates tended to disperse in similar directions (P = 0.09). A 4-lane interstate highway altered dispersal directions (P = 0.001). Dispersal is a strong innate behavior of red foxes (especially males) that results in many individuals of both sexes traveling far from natal areas. Because dispersal distance was unaffected by fox density, populations can be rebuilt and diseases transmitted long distances regardless of fox abundance.

Dispersion parameters: impact on calculated reactor accident consequences

Energy Technology Data Exchange (ETDEWEB)

Aldrich, D.C.

1979-01-01

Much attention has been given in recent years to the modeling of the atmospheric dispersion of pollutants released from a point source. Numerous recommendations have been made concerning the choice of appropriate dispersion parameters. A series of calculations has been performed to determine the impact of these recommendations on the calculated consequences of large reactor accidents. Results are presented and compared in this paper.

Influence of a source line position on results of EM observations applied to the diagnostics of underground heating system pipelines in urban area

Science.gov (United States)

Vetrov, A.

2009-05-01

The condition of underground constructions, communication and supply systems in the cities has to be periodically monitored and controlled in order to prevent their breakage, which can result in serious accident, especially in urban area. The most risk of damage have the underground construction made of steal such as pipelines widely used for water, gas and heat supply. To ensure the pipeline survivability it is necessary to carry out the operative and inexpensive control of pipelines condition. Induced electromagnetic methods of geophysics can be applied to provide such diagnostics. The highly developed surface in urbane area is one of cause hampering the realization of electromagnetic methods of diagnostics. The main problem is in finding of an appropriate place for the source line and electrodes on a limited surface area and their optimal position relative to the observation path to minimize their influence on observed data. Author made a number of experiments of an underground heating system pipeline diagnostics using different position of the source line and electrodes. The experiments were made on a 200 meters section over 2 meters deep pipeline. The admissible length of the source line and angle between the source line and the observation path were determined. The minimal length of the source line for the experiment conditions and accuracy made 30 meters, the maximum admissible angle departure from the perpendicular position made 30 degrees. The work was undertaken in cooperation with diagnostics company DIsSO, Saint-Petersburg, Russia.

Novel coherent supercontinuum light sources based on all-normal dispersion fibers

Energy Technology Data Exchange (ETDEWEB)

Heidt, Alexander

2011-07-05

The concept of broadband coherent supercontinuum (SC) generation in all-normal dispersion (ANDi) fibers in the near-infrared, visible and ultraviolet (UV) spectral regions is introduced and investigated in detail. In numerical studies, explicit design criteria are established for ANDi photonic crystal fiber (PCF) designs that allow the generation of flat and smooth ultrabroad spectral profiles without significant fine structure and with excellent stability and coherence properties. The key benefit of SC generation in ANDi fibers is the conservation of a single ultrashort pulse in the time domain with smooth and recompressible phase distribution. In the numerical investigation of the SC generation dynamics self-phase modulation and optical wave breaking are identified as the dominant nonlinear effects responsible for the nonlinear spectral broadening. It is further demonstrated that coherence properties, spectral bandwidth and temporal compressibility are independent of input pulse duration for constant peak power. The numerical predictions are in excellent agreement with experimental results obtained in two realizations of ANDi PCF optimized for the near-infrared and visible spectral region. In these experiments, the broadest SC spectrum generated in the normal dispersion regime of an optical fiber to date is achieved. The exceptional temporal properties of the generated SC pulses are verified experimentally and their applicability for the time-resolved study of molecular dynamics in ultrafast transient absorption spectroscopy is demonstrated. In an additional nonlinear pulse compression experiment, the SC pulses obtained in a short piece of ANDi PCF could be temporally recompressed to sub-two cycle durations by linear chirp compensation. Numerical simulations show that even shorter pulse durations with excellent quality can be achieved by full phase compensation. The concept is further extended into the UV spectral regime by considering tapered optical fibers with

CO Spectral Line Energy Distributions in Galactic Sources: Empirical Interpretation of Extragalactic Observations

Energy Technology Data Exchange (ETDEWEB)

Indriolo, Nick; Bergin, E. A. [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Goicoechea, J. R.; Cernicharo, J. [Grupo de Astrofísica Molecular, Instituto de Ciencia de Materiales de Madrid (CSIC) E-28049 Madrid (Spain); Gerin, M.; Gusdorf, A. [LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, École normale supérieure, F-75005, Paris (France); Lis, D. C. [LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75014, Paris (France); Schilke, P., E-mail: nindriolo@stsci.edu [I. Physikalisches Institut der Universität zu Köln, Zülpicher Str. 77, D-50937 Köln (Germany)

2017-02-10

The relative populations in rotational transitions of CO can be useful for inferring gas conditions and excitation mechanisms at work in the interstellar medium. We present CO emission lines from rotational transitions observed with Herschel /HIFI in the star-forming cores Orion S, Orion KL, Sgr B2(M), and W49N. Integrated line fluxes from these observations are combined with those from Herschel /PACS observations of the same sources to construct CO spectral line energy distributions (SLEDs) from 5≤ J{sub u} ≤ 48. These CO SLEDs are compared to those reported in other galaxies, with the intention of empirically determining which mechanisms dominate excitation in such systems. We find that CO SLEDs in Galactic star-forming cores cannot be used to reproduce those observed in other galaxies, although the discrepancies arise primarily as a result of beam filling factors. The much larger regions sampled by the Herschel beams at distances of several megaparsecs contain significant amounts of cooler gas, which dominate the extragalactic CO SLEDs, in contrast to observations of Galactic star-forming regions, which are focused specifically on cores containing primarily hot molecular gas.

Time-Frequency Analysis of the Dispersion of Lamb Modes

Science.gov (United States)

Prosser, W. H.; Seale, Michael D.; Smith, Barry T.

1999-01-01

Accurate knowledge of the velocity dispersion of Lamb modes is important for ultrasonic nondestructive evaluation methods used in detecting and locating flaws in thin plates and in determining their elastic stiffness coefficients. Lamb mode dispersion is also important in the acoustic emission technique for accurately triangulating the location of emissions in thin plates. In this research, the ability to characterize Lamb mode dispersion through a time-frequency analysis (the pseudo Wigner-Ville distribution) was demonstrated. A major advantage of time-frequency methods is the ability to analyze acoustic signals containing multiple propagation modes, which overlap and superimpose in the time domain signal. By combining time-frequency analysis with a broadband acoustic excitation source, the dispersion of multiple Lamb modes over a wide frequency range can be determined from as little as a single measurement. In addition, the technique provides a direct measurement of the group velocity dispersion. The technique was first demonstrated in the analysis of a simulated waveform in an aluminum plate in which the Lamb mode dispersion was well known. Portions of the dispersion curves of the A(sub 0), A(sub 1), S(sub 0), and S(sub 2)Lamb modes were obtained from this one waveform. The technique was also applied for the analysis of experimental waveforms from a unidirectional graphite/epoxy composite plate. Measurements were made both along, and perpendicular to the fiber direction. In this case, the signals contained only the lowest order symmetric and antisymmetric modes. A least squares fit of the results from several source to detector distances was used. Theoretical dispersion curves were calculated and are shown to be in good agreement with experimental results.

Broadband microwave frequency doubler based on left-handed nonlinear transmission lines

International Nuclear Information System (INIS)

Huang Jie; Gu Wenwen; Zhao Qian

2017-01-01

A bandwidth microwave second harmonic generator is successfully designed using composite right/left-handed nonlinear transmission lines (CRLH NLTLs) in a GaAs monolithic microwave integrated circuit (MMIC) technology. The structure parameters of CRLH NLTLs, e.g. host transmission line, rectangular spiral inductor, and nonlinear capacitor, have a great impact on the second harmonic performance enhancement in terms of second harmonic frequency, output power, and conversion efficiency. It has been experimentally demonstrated that the second harmonic frequency is determined by the anomalous dispersion of CRLH NLTLs and can be significantly improved by effectively adjusting these structure parameters. A good agreement between the measured and simulated second harmonic performances of Ka-band CRLH NLTLs frequency multipliers is successfully achieved, which further validates the design approach of frequency multipliers on CRLH NLTLs and indicates the potentials of CRLH NLTLs in terms of the generation of microwave and millimeter-wave signal source. (paper)

Relationship between the complex susceptibility and the plasma dispersion function

Energy Technology Data Exchange (ETDEWEB)

Jimenez D, H.; Cabral P, A

1991-04-15

It is shown that when magnetization processes in a spin system and resonant excitation of spin n states occur in the presence of internal and or external random line-broadening mechanisms, the complex magnetic susceptibility of the plasma dispersion function. letter could be useful spin in system is proportional to the relationship found in this spectroscopies such as EPR and NMR, for example, as its fitting to experimental absorption and dispersion profiles produces their Lorentzian and Gaussian contents. (Author)

Relationship between the complex susceptibility and the plasma dispersion function

International Nuclear Information System (INIS)

Jimenez D, H.; Cabral P, A.

1991-04-01

It is shown that when magnetization processes in a spin system and resonant excitation of spin n states occur in the presence of internal and or external random line-broadening mechanisms, the complex magnetic susceptibility of the plasma dispersion function. letter could be useful spin in system is proportional to the relationship found in this spectroscopies such as EPR and NMR, for example, as its fitting to experimental absorption and dispersion profiles produces their Lorentzian and Gaussian contents. (Author)

Source-receptor probability of atmospheric long-distance dispersal of viruses to Israel from the eastern Mediterranean area.

Science.gov (United States)

Klausner, Z; Klement, E; Fattal, E

2018-02-01

Viruses that affect the health of humans and farm animals can spread over long distances via atmospheric mechanisms. The phenomenon of atmospheric long-distance dispersal (LDD) is associated with severe consequences because it may introduce pathogens into new areas. The introduction of new pathogens to Israel was attributed to LDD events numerous times. This provided the motivation for this study which is aimed to identify all the locations in the eastern Mediterranean that may serve as sources for pathogen incursion into Israel via LDD. This aim was achieved by calculating source-receptor relationship probability maps. These maps describe the probability that an infected vector or viral aerosol, once airborne, will have an atmospheric route that can transport it to a distant location. The resultant probability maps demonstrate a seasonal tendency in the probability of specific areas to serve as sources for pathogen LDD into Israel. Specifically, Cyprus' season is the summer; southern Turkey and the Greek islands of Crete, Karpathos and Rhodes are associated with spring and summer; lower Egypt and Jordan may serve as sources all year round, except the summer months. The method used in this study can easily be implemented to any other geographic region. The importance of this study is the ability to provide a climatologically valid and accurate risk assessment tool to support long-term decisions regarding preparatory actions for future outbreaks long before a specific outbreak occurs. © 2017 Blackwell Verlag GmbH.

Dispersion-Engineered Traveling Wave Kinetic Inductance Parametric Amplifier

Science.gov (United States)

Zmuidzinas, Jonas (Inventor); Day, Peter K. (Inventor)

2014-01-01

A traveling wave kinetic inductance parametric amplifier comprises a superconducting transmission line and a dispersion control element. The transmission line can include periodic variations of its dimension along its length. The superconducting material can include a high normal state resistivity material. In some instances the high normal state resistivity material includes nitrogen and a metal selected from the group consisting of titanium, niobium and vanadium. The traveling wave kinetic inductance parametric amplifier is expected to exhibit a noise temperature below 100 mK/GHz.

Accurate Recovery of H i Velocity Dispersion from Radio Interferometers

Energy Technology Data Exchange (ETDEWEB)

Ianjamasimanana, R. [Max-Planck Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany); Blok, W. J. G. de [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Heald, George H., E-mail: roger@mpia.de, E-mail: blok@astron.nl, E-mail: George.Heald@csiro.au [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV, Groningen (Netherlands)

2017-05-01

Gas velocity dispersion measures the amount of disordered motion of a rotating disk. Accurate estimates of this parameter are of the utmost importance because the parameter is directly linked to disk stability and star formation. A global measure of the gas velocity dispersion can be inferred from the width of the atomic hydrogen (H i) 21 cm line. We explore how several systematic effects involved in the production of H i cubes affect the estimate of H i velocity dispersion. We do so by comparing the H i velocity dispersion derived from different types of data cubes provided by The H i Nearby Galaxy Survey. We find that residual-scaled cubes best recover the H i velocity dispersion, independent of the weighting scheme used and for a large range of signal-to-noise ratio. For H i observations, where the dirty beam is substantially different from a Gaussian, the velocity dispersion values are overestimated unless the cubes are cleaned close to (e.g., ∼1.5 times) the noise level.

Accounting for Field-Scale Dry Deposition in Backward Lagrangian Stochastic Dispersion Modelling of NH3 Emissions

Directory of Open Access Journals (Sweden)

Christoph Häni

2018-04-01

Full Text Available A controlled ammonia (NH3 release experiment was performed at a grassland site. The aim was to quantify the effect of dry deposition between the source and the receptors (NH3 measurement locations on emission rate estimates by means of inverse dispersion modelling. NH3 was released for three hours at a constant rate of Q = 6.29 mg s−1 from a grid of 36 orifices spread over an area of 250 m2. The increase in line-integrated NH3 concentration was measured with open-path optical miniDOAS devices at different locations downwind of the artificial source. Using a backward Lagrangian stochastic (bLS dispersion model (bLSmodelR, the fraction of the modelled release rate to the emitted NH3 ( Q bLS / Q was calculated from the measurements of the individual instruments. Q bLS / Q was found to be systematically lower than 1, on average between 0.69 and 0.91, depending on the location of the receptor. We hypothesized that NH3 dry deposition to grass and soil surfaces was the main factor responsible for the observed depletion of NH3 between source and receptor. A dry deposition algorithm based on a deposition velocity approach was included in the bLS modelling. Model deposition velocities were evaluated from a ‘big-leaf’ canopy resistance analogy. Canopy resistances (generally termed R c that provided Q bLS / Q = 1 ranged from 75 to 290 s m−1, showing that surface removal of NH3 by dry deposition can plausibly explain the original underestimation of Q bLS / Q . The inclusion of a dry deposition process in dispersion modelling is crucial for emission estimates, which are based on concentration measurements of depositing tracers downwind of homogeneous area sources or heterogeneously-distributed hot spots, such as, e.g., urine patches on pastures in the case of NH3.

Light-pressure-induced nonlinear dispersion of a laser field interacting with an atomic gas

International Nuclear Information System (INIS)

Grimm, R.; Mlynek, J.

1990-01-01

We report on detailed studies of the effect of resonant light pressure on the optical response of an atomic gas to a single monochromatic laser field. In this very elementary situation of laser spectroscopy, the redistribution of atomic velocities that is induced by spontaneous light pressure leads to a novel contribution to the optical dispersion curve of the medium. This light-pressure-induced dispersion phenomenon displays a pronounced nonlinear dependence on the laser intensity. Moreover, for a given intensity, its strength is closely related to the laser beam diameter. As most important feature, this light-pressure-induced dispersion displays an even symmetry with respect to the optical detuning from line center. As a result, the total Doppler-broadened dispersion curve of the gas can become asymmetric, and a significant shift of the dispersion line center can occur. In addition to a detailed theoretical description of the phenomenon, we report on its experimental investigation on the λ=555.6 nm 1 S 0 - 3 P 1 transition in atomic ytterbium vapor with the use of frequency-modulation spectroscopy. The experimental findings are in good quantitative agreement with theoretical predictions

Numerical methods of estimating the dispersion of radionuclides in atmosphere

International Nuclear Information System (INIS)

Vladu, Mihaela; Ghitulescu, Alina; Popescu, Gheorghe; Piciorea, Iuliana

2007-01-01

Full text: The paper presents the method of dispersion calculation, witch can be applied for the DLE calculation. This is necessary to ensure a secure performance of the Experimental Pilot Plant for Tritium and Deuterium Separation (using the technology for detritiation based upon isotope catalytic exchange between tritiated heavy water and deuterium followed by cryogenic distillation of the hydrogen isotopes). For the calculation of the dispersion of radioactivity effluents in the atmosphere, at a given distance between source and receiver, the Gaussian mathematical model was used. This model is currently applied for estimating the long-term results of dispersion in case of continuous or intermittent emissions as basic information for long-term radioprotection measures for areas of the order of kilometres from the source. We have considered intermittent or continuous emissions of intensity lower than 1% per day relative to the annual emission. It is supposed that the radioactive material released into environment presents a gaussian dispersion both in horizontal and vertical plan. The local dispersion parameters could be determined directly with turbulence measurements or indirectly by determination of atmospheric stability. Weather parameters for characterizing the atmospheric dispersion include: - direction of wind relative to the source; - the speed of the wind at the height of emission; - parameters of dispersion to different distances, depending on the atmospheric turbulence which characterizes the mixing of radioactive materials in the atmosphere; - atmospheric stability range; - the height of mixture stratum; - the type and intensity of precipitations. The choice of the most adequate version of Gaussian model depends on the relation among the height where effluent emission is in progress, H (m), and the height at which the buildings influence the air motion, HB (m). There were defined three zones of distinct dispersion. This zones can have variable lengths

Axial Dispersion during Hanford Saltcake Washing

International Nuclear Information System (INIS)

Josephson, Gary B.; Geeting, John GH; Lessor, Delbert L.; Barton, William B.

2006-01-01

Clean up of Hanford salt cake wastes begins with dissolution retrieval of the sodium rich salts that make up the dominant majority of mass in the tanks. Water moving through the porous salt cake dissolves the soluble components and also displaces the soluble radionuclides (e.g. 137Cs and 99TcO4- ). The separation that occurs from this displacement, known as Selective dissolution, is an important component in Hanford?s pretreatment of low activity wastes for subsequent Supplemental treatment. This paper describes lab scale testing conducted to evaluate Selective dissolution of cesium from non-radioactive Hanford tank 241-S-112 salt cake simulant containing the primary chemicals found the actual tank. An modified axial dispersion model with increasing axial dispersion was developed to predict cesium removal. The model recognizes that water dissolves the salt cake during washing, which causes an increase in the axial dispersion during the wash. This model was subsequently compared with on-line cesium measurements from the retrieval of tank 241-S-112. The model had remarkably good agreement with both the lab scale and full scale data

The NANOGrav Nine-year Data Set: Measurement and Analysis of Variations in Dispersion Measures

Energy Technology Data Exchange (ETDEWEB)

Jones, M. L.; McLaughlin, M. A.; Lam, M. T. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Cordes, J. M.; Chatterjee, S. [Department of Astronomy and Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853 (United States); Levin, L. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Arzoumanian, Z. [Center for Research and Exploration in Space Science and Technology and X-Ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Crowter, K.; Gonzalez, M. E. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Demorest, P. B. [National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 (United States); Dolch, T. [Department of Physics, Hillsdale College, 33 E. College Street, Hillsdale, MI 49242 (United States); Ellis, J. A; Lazio, T. J. W. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr. Pasadena, CA 91109 (United States); Ferdman, R. D.; Fonseca, E. [Department of Physics, McGill University, 3600 rue Universite, Montreal, QC H3A 2T8 (Canada); Jones, G.; Pennucci, T. T. [Department of Physics, Columbia University, 550 W. 120th St. New York, NY 10027 (United States); Nice, D. J. [Department of Physics, Lafayette College, Easton, PA 18042 (United States); Ransom, S. M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Stinebring, D. R. [Department of Physics and Astronomy, Oberlin College, Oberlin, OH 44074 (United States); and others

2017-06-01

We analyze dispersion measure (DM) variations of 37 millisecond pulsars in the nine-year North American Nanohertz Observatory for Gravitational Waves (NANOGrav) data release and constrain the sources of these variations. DM variations can result from a changing distance between Earth and the pulsar, inhomogeneities in the interstellar medium, and solar effects. Variations are significant for nearly all pulsars, with characteristic timescales comparable to or even shorter than the average spacing between observations. Five pulsars have periodic annual variations, 14 pulsars have monotonically increasing or decreasing trends, and 14 pulsars show both effects. Of the four pulsars with linear trends that have line-of-sight velocity measurements, three are consistent with a changing distance and require an overdensity of free electrons local to the pulsar. Several pulsars show correlations between DM excesses and lines of sight that pass close to the Sun. Mapping of the DM variations as a function of the pulsar trajectory can identify localized interstellar medium features and, in one case, an upper limit to the size of the dispersing region of 4 au. Four pulsars show roughly Kolmogorov structure functions (SFs), and another four show SFs less steep than Kolmogorov. One pulsar has too large an uncertainty to allow comparisons. We discuss explanations for apparent departures from a Kolmogorov-like spectrum, and we show that the presence of other trends and localized features or gradients in the interstellar medium is the most likely cause.

Dispersion strengthening

International Nuclear Information System (INIS)

Scattergood, R.O.; Das, E.S.P.

1976-01-01

Using digital computer-based methods, models for dispersion strengthening can now be developed which take into account many of the important effects that have been neglected in the past. In particular, the self interaction of a dislocation can be treated, and a computer simulation method was developed to determine the flow stress of a random distribution of circular, impenetrable obstacles, taking into account all such interactions. The flow stress values depended on the obstacle sizes and spacings, over and above the usual 1/L dependence where L is the average obstacle spacing. From an analysis of the results, it was found that the main effects of the self interactions can be captured in a line tension analogue in which the obstacles appear to be penetrable

Synchrotron X-Ray Microdiffraction Studies of Electromigration in Interconnect lines at the Advanced Light Source

Energy Technology Data Exchange (ETDEWEB)

Tamura, Nobumichi; Chen, Kai; Kunz, Martin

2009-12-01

Synchrotron polychromatic X-ray microdiffraction is a particularly suitable technique to study in situ the effect of electromigration in metal interconnects as add spatial resolution to grain orientation and strain sensitivity. This technique has been extensively used at the Advanced Light Source to monitor changes in aluminum and copper interconnect test structures while high-density current is passed into them during accelerated tests at elevated temperature. One of the principal findings is the observation of electromigration-induced plasticity in the metal lines that appear during the very early stages of electromigration. In some of the lines, high density of geometrically necessary dislocation are formed leading to additional diffusion paths causing an enhancement of electromigration effect at test temperature.

Analysis of ensembles of moderately saturated interstellar lines

International Nuclear Information System (INIS)

Jenkins, E.B.

1986-01-01

It is shown that the combined equivalent widths for a large population of Gaussian-like interstellar line components, each with different central optical depths tau(0) and velocity dispersions b, exhibit a curve of growth (COG) which closely mimics that of a single, pure Gaussian distribution in velocity. Two parametric distributions functions for the line populations are considered: a bivariate Gaussian for tau(0) and b and a power law distribution for tau(0) combined with a Gaussian dispersion for b. First, COGs for populations having an extremely large number of nonoverlapping components are derived, and the implications are shown by focusing on the doublet-ratio analysis for a pair of lines whose f-values differ by a factor of two. The consequences of having, instead of an almost infinite number of lines, a relatively small collection of components added together for each member of a doublet are examined. The theory of how the equivalent widths grow for populations of overlapping Gaussian profiles is developed. Examples of the composite COG analysis applied to existing collections of high-resolution interstellar line data are presented. 39 references

Evaluation of different numerical methodologies for dispersion of air pollutants in an urban environment

International Nuclear Information System (INIS)

Mumovic, D.; Crowther, J.M.; Stevanovic, Z.

2003-01-01

Since 1950 the world population has more than doubled but meanwhile the global number of cars has increased by a factor of 10. In that same period the fraction of people living in urban areas has increased by a factor of 4. Apart from large point-sources of local air pollution, traffic induced pollution is now the most significant contributor to urban air quality in city centres, particularly for carbon monoxide, oxides of nitrogen and fine particulate matter. Until recently, pollutant dispersion in urban areas has usually been numerically investigated by using empirical models, such as the Gaussian plume model, or by extensions of this technique to line sources and multiple sources. More recently, advanced computational fluid dynamics (CFD) simulations have been attempted but have been mainly two-dimensional and often encompassing only a single street canyon. This paper provides a comprehensive, critical evaluation of dispersion of pollutants in urban areas. A three-dimensional flow model has been set-up for a staggered crossroad, using the Navier-Stokes equations and the conservation equation for species concentration. The effect of using several different turbulence models, including the k-ε model, modifications and extensions, has been investigated. Cartesian coordinates have been used in connection with the Partial Solution Algorithm (PARSOL) and Body Fitted Coordinates (BFC). The effects of several different numerical algorithms for discretization of differential equations have also been studied. More than thirty cases are analysed, and the main results are compared with wind tunnel experiments. The numerical results are presented as non-dimensional values to facilitate comparison between experimental and numerical studies. It has been shown that the numerical studies have been able to simulate the air-flow in urban areas and confirm, qualitatively, the previous field observations and wind tunnel results. This success encouraged the authors to extend such

Evaluation of different numerical methodologies for dispersion of air pollutants in an urban environment

Energy Technology Data Exchange (ETDEWEB)

Mumovic, D.; Crowther, J.M. [Glasgow Caledonian Univ., School of Built and Natural Environment, Glasgow (United Kingdom)]. E-mail: dmumov10@caledonian.ac.uk; Stevanovic, Z. [Univ. of Belgrade, Inst. of Nuclear Sciences, Belgrade (Serbia and Montenegro)

2003-07-01

Since 1950 the world population has more than doubled but meanwhile the global number of cars has increased by a factor of 10. In that same period the fraction of people living in urban areas has increased by a factor of 4. Apart from large point-sources of local air pollution, traffic induced pollution is now the most significant contributor to urban air quality in city centres, particularly for carbon monoxide, oxides of nitrogen and fine particulate matter. Until recently, pollutant dispersion in urban areas has usually been numerically investigated by using empirical models, such as the Gaussian plume model, or by extensions of this technique to line sources and multiple sources. More recently, advanced computational fluid dynamics (CFD) simulations have been attempted but have been mainly two-dimensional and often encompassing only a single street canyon. This paper provides a comprehensive, critical evaluation of dispersion of pollutants in urban areas. A three-dimensional flow model has been set-up for a staggered crossroad, using the Navier-Stokes equations and the conservation equation for species concentration. The effect of using several different turbulence models, including the k-{epsilon} model, modifications and extensions, has been investigated. Cartesian coordinates have been used in connection with the Partial Solution Algorithm (PARSOL) and Body Fitted Coordinates (BFC). The effects of several different numerical algorithms for discretization of differential equations have also been studied. More than thirty cases are analysed, and the main results are compared with wind tunnel experiments. The numerical results are presented as non-dimensional values to facilitate comparison between experimental and numerical studies. It has been shown that the numerical studies have been able to simulate the air-flow in urban areas and confirm, qualitatively, the previous field observations and wind tunnel results. This success encouraged the authors to extend

Viability utilization of one Se sup(75) source in the analysis of uranium, thorium and rare earths for use on energy dispersive x-ray fluorescence

International Nuclear Information System (INIS)

Nova Mussel, W. da.

1989-01-01

This work is a study about the viable utilization of one Se sup(75) source as an excitation source for the use of Energy Dispersive X-Ray Fluorescence (EDXRF), in the analysis of Uranium, Thorium and the Rare Earths. The following arrangement was build up: a HPGE detector, two Se sup(75) sources in 30 sup(0) positions of castle, deadtime of 5%. Using this arrangement the calibration curve for U and Th was measured and the angular correlation coeficient was r+ 0,999, and for the Rare Earths was superior r+ 0,960. The answer given for this system was considered very fine. (author)

Commissioning and Operation of the FNAL Front end Injection Line and Ion Sources.

Energy Technology Data Exchange (ETDEWEB)

Karns, Patrick R. [Indiana Univ., Bloomington, IN (United States)

2015-09-01

This thesis documents the efforts made in commissioning and operating the RFQ Injection Line (RIL) as a replacement for the Cockcroft Walton front end. The Low Energy Beam Transport (LEBT) was assembled and tested with multiwire position and emittance monitor measurements. The Radio Frequency Quadrupole (RFQ) commissioning was completed with the same measurements as well as output beam energy measurements that showed it initially accelerated beam only to 700 keV, which was 50 keV lower than the design energy. Working with the manufacturer solutions were found and instituted to continue testing. The Medium Energy Beam Transport (MEBT) was then connected as the RIL was installed as the new front end of Linac. Testing gave way to operation when the new front end was used as the source of all High Energy Physics (HEP) beam for Fermi National Accelerator Laboratory (FNAL). The magnetron ion source that provides the H- beam for the front end required several changes and eventual upgrades to operate well; such as new source operating points for vacuum pressure and cesium admixture, and new materials for critical source components. Further research was conducted on the cathode geometry and nitrogen doping of the hydrogen gas as well as using solid state switches for the extractor system high voltage.

Determination of cobalt in biological samples by line-source and high-resolution continuum source graphite furnace atomic absorption spectrometry using solid sampling or alkaline treatment

International Nuclear Information System (INIS)

Ribeiro, Anderson Schwingel; Vieira, Mariana Antunes; Furtado da Silva, Alessandra; Borges, Daniel L. Gallindo; Welz, Bernhard; Heitmann, Uwe; Curtius, Adilson Jose

2005-01-01

Two procedures for the determination of Co in biological samples by graphite furnace atomic absorption spectrometry (GF AAS) were compared: solid sampling (SS) and alkaline treatment with tetramethylammonium hydroxide (TMAH) using two different instruments for the investigation: a conventional line-source (LS) atomic absorption spectrometer and a prototype high-resolution continuum source atomic absorption spectrometer. For the direct introduction of the solid samples, certified reference materials (CRM) were ground to a particle size ≤50 μm. Alkaline treatment was carried out by placing about 250 mg of the sample in polypropylene flasks, adding 2 mL of 25% m/v tetramethylammonium hydroxide and de-ionized water. Due to its unique capacity of providing a 3-D spectral plot, a high-resolution continuum source (HR-CS) graphite furnace atomic absorption spectrometry was used as a tool to evaluate potential spectral interferences, including background absorption for both sample introduction procedures, revealing that a continuous background preceded the atomic signal for pyrolysis temperatures lower than 700 deg. C. Molecular absorption bands with pronounced rotational fine structure appeared for atomization temperatures >1800 deg. C probably as a consequence of the formation of PO. After optimization had been carried out using high resolution continuum source atomic absorption spectrometry, the optimized conditions were adopted also for line-source atomic absorption spectrometry. Six biological certified reference materials were analyzed, with calibration against aqueous standards, resulting in agreement with the certified values (according to the t-test for a 95% confidence level) and in detection limits as low as 5 ng g -1

Regional-scale input of dispersed and discrete volcanic ash to the Izu-Bonin and Mariana subduction zones

Science.gov (United States)

Scudder, Rachel P.; Murray, Richard W.; Schindlbeck, Julie C.; Kutterolf, Steffen; Hauff, Folkmar; McKinley, Claire C.

2014-11-01

We have geochemically and statistically characterized bulk marine sediment and ash layers at Ocean Drilling Program Site 1149 (Izu-Bonin Arc) and Deep Sea Drilling Project Site 52 (Mariana Arc), and have quantified that multiple dispersed ash sources collectively comprise ˜30-35% of the hemipelagic sediment mass entering the Izu-Bonin-Mariana subduction system. Multivariate statistical analyses indicate that the bulk sediment at Site 1149 is a mixture of Chinese Loess, a second compositionally distinct eolian source, a dispersed mafic ash, and a dispersed felsic ash. We interpret the source of these ashes as, respectively, being basalt from the Izu-Bonin Front Arc (IBFA) and rhyolite from the Honshu Arc. Sr-, Nd-, and Pb isotopic analyses of the bulk sediment are consistent with the chemical/statistical-based interpretations. Comparison of the mass accumulation rate of the dispersed ash component to discrete ash layer parameters (thickness, sedimentation rate, and number of layers) suggests that eruption frequency, rather than eruption size, drives the dispersed ash record. At Site 52, the geochemistry and statistical modeling indicates that Chinese Loess, IBFA, dispersed BNN (boninite from Izu-Bonin), and a dispersed felsic ash of unknown origin are the sources. At Site 1149, the ash layers and the dispersed ash are compositionally coupled, whereas at Site 52 they are decoupled in that there are no boninite layers, yet boninite is dispersed within the sediment. Changes in the volcanic and eolian inputs through time indicate strong arc-related and climate-related controls.

Insertion device and beam line plans for the Advanced Photon Source: A report and recommendations by the Insertion Device and Beam Line Planning Committee

International Nuclear Information System (INIS)

1988-02-01

In the 7-GeV Advanced Photon Source (APS) Conceptual Design Report (CDR), fifteen complete experimental beam lines were specified in order to establish a representative technical and cost base for the components involved. In order to optimize the composition of the insertion devices and the beam line, these funds are considered a ''Trust Fund.'' The present report evaluates the optimization for the distribution of these funds so that the short- and long-term research programs will be most productive, making the facility more attractive from the user's point of view. It is recommended that part of the ''Trust Fund'' be used for the construction of the insertion devices, the front-end components, and the first-optics, minimizing the cost to potential users of completing a beam line. In addition, the possibility of cost savings resulting from replication and standardization of high multiplicity components (such as IDs, front ends, and first-optics instrumentation) is addressed. 2 refs., 5 tabs

Development of a new MT system using the commercial power line as a source (Part 3)

Energy Technology Data Exchange (ETDEWEB)

Tsubota, Koji; Noritake, Kazumitsu; Miyata, Hatsuho; Sakuma, Hideki; Saito, Akira

1988-10-01

PLMT method is an electromagnetic induction method which uses a commercial power line as a source of electomagnetic energy, and enables accurate measurement in short periods. A numeric calculation example of the effect of distance from a power line as well as the results of actual measurements carried out in the Sekiret mining area (Niger) and Kushikino area, Kagoshima Prefecture are reported. Possibility of estimating average ground resistivity by numerical calculation is demonstrated using the electric field and magnetic field generated by power lines. In the measurement in the Sekiret mining area, Niger, north-south electric field and east-west magnetic field were measured from directly under the power line to the distance of 20 km. The relation of the amplitudes of electric field and magnetic field with the distance is shown. The theoretic curve of 0.02 (mho/m) conductivity agreed well with the value mesured in the area about 1 km from the power line. In the measurement at Kushikino area, the value agrees well with the theoretical curve of 0.01 conductivity, whose average resistivity is considered to be about 100 {Omega}m. 6 references, 11 figures.

Dispersal of micro-organisms in commercial defeathering systems.

Science.gov (United States)

Allen, V M; Tinker, D B; Hinton, M H; Wathes, C M

2003-03-01

1. The extent of cross contamination between carcases and the dispersal of micro-organisms to the environs during defeathering was measured in a commercial processing plant. 2. Defeathering reduced the numbers of a marker organism, a nalidixic acid-resistant strain of Escherichia coli K12, on inoculated carcases but dispersed the organism on to preceding and following carcases. 3. The pattern of microbial dispersal during defeathering was similar for naturally occurring bacteria on the carcase, for example, total aerobic counts and counts of presumptive coliforms, suggesting that the marker organism mimics the natural situation realistically. 4. The majority of feathers, together with micro-organisms, were removed during the first 10 s of the defeathering process, which was completed in 45 s, indicating that control measures to minimise cross contamination would be most effective if applied in the early stages of the process. 5. The method of defeathering used by the machine influenced the pattern of microbial dispersal and the extent of cross contamination to other carcases on the same processing line.

Copper Heat Exchanger for the External Auxiliary Bus-Bars Routing Line in the LHC Insertion Regions

CERN Document Server

Garion, C; Seyvet, F; Sitko, M; Skoczen, B; Tock, J P

2006-01-01

The corrector magnets and the main quadrupoles of the LHC dispersion suppressors are powered by a special superconducting line (called auxiliary bus-bars line N), external to the cold mass and housed in a 50 mm diameter stainless steel tube fixed to the cold mass. As the line is periodically connected to the cold mass, the same gaseous and liquid helium cools both the magnets and the line. The final sub-cooling process (from around 4.5 K down to 1.9 K) consists in the phase transformation from liquid to superfluid helium. Heat is extracted from the line through the magnets via their point of junction. In dispersion suppressor zones, approximately 40 m long, the sub-cooling of the line is slightly delayed with respect to the magnets. This might have an impact on the readiness of the accelerator for operation. In order to accelerate the process, a special heat exchanger has been designed. It is located in the middle of the dispersion suppressor portion of the line. Its main function consists in providing a loca...

Branch migration and the international dispersal of families.

Science.gov (United States)

Parr, N; Lucas, D; Mok, M

2000-01-01

This paper discusses the dispersal of facilities where family members migrate to different destination countries. Terminology for internationally dispersed families is proposed, and the term branch migration is suggested for the migration of related people from the same source country to different destination countries. Data from two 1993 surveys of senior secondary students show that 22% of Sydney students and 20% of Hong Kong students have relatives in two or more other countries. The data suggest that many Asian migrant families have branched between the US, Canada, Australia and other migrant-receiving nations. The causes and implications of the international dispersal of families are discussed.

Gulf-Wide Information System, Environmental Sensitivity Index Dispersant Preapproval Zone, Geographic NAD83, LDWF (2001) [esi_dispersant_preapproval_zone_LDWF_2001

Data.gov (United States)

Louisiana Geographic Information Center — This data set contains dispersant preapproval zones in coastal Louisiana. Feature-specific contact, type, and source information are stored in relational data tables...

Open Burn/Open Detonation Dispersion Model (OBODM) User's Guide. Volume I. User's Instructions

National Research Council Canada - National Science Library

Bjorklund, Jay

1998-01-01

...) of obsolete munitions and solid propellants. OBODM uses loud/plume rise, dispersion, and deposition algorithms taken from existing models for instantaneous and quasi-continuous sources to predict the downwind transport and dispersion...

Some fundamental problems relating to optical fibres. II. The ultimate bandwidth performance of optical fibre transmission lines

International Nuclear Information System (INIS)

Gambling, W.A.

1977-01-01

Optical fibre transmission lines can be divided broadly into two types, namely single mode and multimode. The bandwidth of the former is limited by the variation in group velocity with frequency caused by mode dispersion and material dispersion, with predicted values of tens of gigahertz over tens of kilometres for a monochromatic carrier, falling to approximately l GHz over 1km for a typical injection laser. Multimode fibres have the additional limitation of group delay between the various propagating modes. Several schemes have been suggested for reducing this effect, such as: (a) exciting only a few modes (ideally one) in a fibre exhibiting no mode conversion, (b) inducing coupling between bound modes but not into radiating modes, and (c) equalizing the mode velocities by means of a suitable refractive index profile. Most effort is presently being devoted to (c) and it has been shown that the optimum profile is affected by leaky modes and material dispersion. By operating at a wavelength in the region of 1.25μm the effect of material dispersion can be greatly reduced and bandwidths in excess of 1 GHz over 1km might be expected, even with sources of large linewidth. (author)

Numerical study of the Kadomtsev-Petviashvili equation and dispersive shock waves

Science.gov (United States)

Grava, T.; Klein, C.; Pitton, G.

2018-02-01

A detailed numerical study of the long time behaviour of dispersive shock waves in solutions to the Kadomtsev-Petviashvili (KP) I equation is presented. It is shown that modulated lump solutions emerge from the dispersive shock waves. For the description of dispersive shock waves, Whitham modulation equations for KP are obtained. It is shown that the modulation equations near the soliton line are hyperbolic for the KPII equation while they are elliptic for the KPI equation leading to a focusing effect and the formation of lumps. Such a behaviour is similar to the appearance of breathers for the focusing nonlinear Schrödinger equation in the semiclassical limit.

Characterization of exoplanet atmospheres using high-dispersion spectroscopy with the E-ELT and beyond

Directory of Open Access Journals (Sweden)

Snellen Ignas

2013-04-01

Full Text Available Ground-based high-dispersion (R ∼ 100,000 spectroscopy provides unique information on exoplanet atmospheres, inaccessible from space - even using the JWST or other future space telescopes. Recent successes in transmission- and dayside spectroscopy using CRIRES on the Very Large Telescope prelude the enormous discovery potential of high-dispersion spectrographs on the E-ELT, such as METIS in the thermal infrared, and HIRES in the optical/near-infrared. This includes the orbital inclination and masses of hundred(s of non-transiting planets, line-by-line molecular band spectra, planet rotation and global wind patterns, longitudinal spectral variations, and possibly isotopologue ratios. Thinking beyond the E-ELT, we advocate that ultimately a systematic search for oxygen in atmospheres of nearby Earth-like planets can be conducted using large arrays of relatively low-cost flux collector telescopes equipped with high-dispersion spectrographs.

Computation of probabilistic hazard maps and source parameter estimation for volcanic ash transport and dispersion

Energy Technology Data Exchange (ETDEWEB)

Madankan, R. [Department of Mechanical and Aerospace Engineering, University at Buffalo (United States); Pouget, S. [Department of Geology, University at Buffalo (United States); Singla, P., E-mail: psingla@buffalo.edu [Department of Mechanical and Aerospace Engineering, University at Buffalo (United States); Bursik, M. [Department of Geology, University at Buffalo (United States); Dehn, J. [Geophysical Institute, University of Alaska, Fairbanks (United States); Jones, M. [Center for Computational Research, University at Buffalo (United States); Patra, A. [Department of Mechanical and Aerospace Engineering, University at Buffalo (United States); Pavolonis, M. [NOAA-NESDIS, Center for Satellite Applications and Research (United States); Pitman, E.B. [Department of Mathematics, University at Buffalo (United States); Singh, T. [Department of Mechanical and Aerospace Engineering, University at Buffalo (United States); Webley, P. [Geophysical Institute, University of Alaska, Fairbanks (United States)

2014-08-15

Volcanic ash advisory centers are charged with forecasting the movement of volcanic ash plumes, for aviation, health and safety preparation. Deterministic mathematical equations model the advection and dispersion of these plumes. However initial plume conditions – height, profile of particle location, volcanic vent parameters – are known only approximately at best, and other features of the governing system such as the windfield are stochastic. These uncertainties make forecasting plume motion difficult. As a result of these uncertainties, ash advisories based on a deterministic approach tend to be conservative, and many times over/under estimate the extent of a plume. This paper presents an end-to-end framework for generating a probabilistic approach to ash plume forecasting. This framework uses an ensemble of solutions, guided by Conjugate Unscented Transform (CUT) method for evaluating expectation integrals. This ensemble is used to construct a polynomial chaos expansion that can be sampled cheaply, to provide a probabilistic model forecast. The CUT method is then combined with a minimum variance condition, to provide a full posterior pdf of the uncertain source parameters, based on observed satellite imagery. The April 2010 eruption of the Eyjafjallajökull volcano in Iceland is employed as a test example. The puff advection/dispersion model is used to hindcast the motion of the ash plume through time, concentrating on the period 14–16 April 2010. Variability in the height and particle loading of that eruption is introduced through a volcano column model called bent. Output uncertainty due to the assumed uncertain input parameter probability distributions, and a probabilistic spatial-temporal estimate of ash presence are computed.

Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

Science.gov (United States)

Katata, G.; Chino, M.; Kobayashi, T.; Terada, H.; Ota, M.; Nagai, H.; Kajino, M.; Draxler, R.; Hort, M. C.; Malo, A.; Torii, T.; Sanada, Y.

2014-06-01

Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Dai-ichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data with atmospheric model simulations from WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information), and simulations from the oceanic dispersion model SEA-GEARN-FDM, both developed by the authors. A sophisticated deposition scheme, which deals with dry and fogwater depositions, cloud condensation nuclei (CCN) activation and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2 and CH3I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The fallout to the ocean surface calculated by WSPEEDI-II was used as input data for the SEA-GEARN-FDM calculations. Reverse and inverse source-term estimation methods based on coupling the simulations from both models was adopted using air dose rates and concentrations, and sea surface concentrations. The results revealed that the major releases of radionuclides due to FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, the morning of 13 March after the venting event at Unit 3, midnight of 14 March when the SRV (Safely Relief Valve) at Unit 2 was opened three times, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of

Review of specific effects in atmospheric dispersion calculations

International Nuclear Information System (INIS)

Underwood, B.Y.; Cooper, P.J.; Holloway, N.J.; Kaiser, G.D.; Nixon, W.

1984-01-01

This report consists of a series of 7 individual review chapters -written between 1980 and 1983- together with a summary document linking and overviewing the work. The topics covered are as follows: ''atmospheric dispersion in urban environments''; ''topographical effects in nuclear safety studies''; coastal effects and transport over water''; ''time-varying meteorology in consequence assessment''; ''building effects in nuclear safety studies''; effect of variations in mixing height on atmospheric dispersion''; ''the effect of turning of the wind with height on lateral dispersion''. Although the reviews are, on the whole, general in approach, emphasis has been given where appropriate to the impact of various phenomena on the assessment of reactor accident consequences. In general the work focuses on the 0-100 km range of distance downwind of the source. The reviews fulfil several functions: they serve as introductions to the subject areas; they outline theoretical and experimental developments; they act as reference documents providing a copious source of references for more detailed investigation of particular points; they raise unresolved technical issues and attempt to indicate principal uncertainties; they point to areas requiring further development

Validation Study for an Atmospheric Dispersion Model, Using Effective Source Heights Determined from Wind Tunnel Experiments in Nuclear Safety Analysis

Directory of Open Access Journals (Sweden)

Masamichi Oura

2018-03-01

Full Text Available For more than fifty years, atmospheric dispersion predictions based on the joint use of a Gaussian plume model and wind tunnel experiments have been applied in both Japan and the U.K. for the evaluation of public radiation exposure in nuclear safety analysis. The effective source height used in the Gaussian model is determined from ground-level concentration data obtained by a wind tunnel experiment using a scaled terrain and site model. In the present paper, the concentrations calculated by this method are compared with data observed over complex terrain in the field, under a number of meteorological conditions. Good agreement was confirmed in near-neutral and unstable stabilities. However, it was found to be necessary to reduce the effective source height by 50% in order to achieve a conservative estimation of the field observations in a stable atmosphere.

EFFECT OF HEAT-DISPERSING ON STICKIES AND THEIR REMOVAL IN POST-FLOTATION

OpenAIRE

Yang Gao,; Menghua Qin,; Hailong Yu,; Fengshan Zhang

2012-01-01

The effect of heat-dispersing on sticky substances in a deinking pulping line was studied under different conditions including varying temperature, disc clearance, and pulp consistency. Sticky substances were quantitatively investigated before and after the heat-dispersing, and categorized into macro-, mini-, and micro-stickies as well as dissolved and colloidal substances. Meanwhile, their extents of removal in post-flotation were evaluated. The results showed that raising temperature, reduc...

Herschel SPIRE FTS spectral line source calibrators

DEFF Research Database (Denmark)

Hopwood, Rosalind; Polehampton, Edward; Valtchanov, Ivan

2015-01-01

We present a summary of the Herschel SPIRE/FTS calibration programme to monitor the repeatability of spectral lines. Observations of planetary nebulae and post-AGB stars are used to assess repeatability and model the asymmetry of the instrument line shape.......We present a summary of the Herschel SPIRE/FTS calibration programme to monitor the repeatability of spectral lines. Observations of planetary nebulae and post-AGB stars are used to assess repeatability and model the asymmetry of the instrument line shape....

DNA fingerprinting validates seed dispersal curves from observational studies in the neotropical legume parkia.

Science.gov (United States)

Heymann, Eckhard W; Lüttmann, Kathrin; Michalczyk, Inga M; Saboya, Pedro Pablo Pinedo; Ziegenhagen, Birgit; Bialozyt, Ronald

2012-01-01

Determining the distances over which seeds are dispersed is a crucial component for examining spatial patterns of seed dispersal and their consequences for plant reproductive success and population structure. However, following the fate of individual seeds after removal from the source tree till deposition at a distant place is generally extremely difficult. Here we provide a comparison of observationally and genetically determined seed dispersal distances and dispersal curves in a Neotropical animal-plant system. In a field study on the dispersal of seeds of three Parkia (Fabaceae) species by two Neotropical primate species, Saguinus fuscicollis and Saguinus mystax, in Peruvian Amazonia, we observationally determined dispersal distances. These dispersal distances were then validated through DNA fingerprinting, by matching DNA from the maternally derived seed coat to DNA from potential source trees. We found that dispersal distances are strongly right-skewed, and that distributions obtained through observational and genetic methods and fitted distributions do not differ significantly from each other. Our study showed that seed dispersal distances can be reliably estimated through observational methods when a strict criterion for inclusion of seeds is observed. Furthermore, dispersal distances produced by the two primate species indicated that these primates fulfil one of the criteria for efficient seed dispersers. Finally, our study demonstrated that DNA extraction methods so far employed for temperate plant species can be successfully used for hard-seeded tropical plants.

Sources of dispersion in industrial radiography

International Nuclear Information System (INIS)

Ruault, P.A.

1985-01-01

Maximum value of divergence produced by the different parameters are summed up. Parameters examined include the emulsion (aging, processing), the source (filtration, energy, angle), the dosimetry, the object and the print. In the case of testing in the same conditions errors are relatively low but for testing the same object after a long time errors can be important [fr

Production of Flocculants, Adsorbents, and Dispersants from Lignin.

Science.gov (United States)

Chen, Jiachuan; Eraghi Kazzaz, Armin; AlipoorMazandarani, Niloofar; Hosseinpour Feizi, Zahra; Fatehi, Pedram

2018-04-10

Currently, lignin is mainly produced in pulping processes, but it is considered as an under-utilized chemical since it is being mainly used as a fuel source. Lignin contains many hydroxyl groups that can participate in chemical reactions to produce value-added products. Flocculants, adsorbents, and dispersants have a wide range of applications in industry, but they are mainly oil-based chemicals and expensive. This paper reviews the pathways to produce water soluble lignin-based flocculants, adsorbents, and dispersants. It provides information on the recent progress in the possible use of these lignin-based flocculants, adsorbents, and dispersants. It also critically discusses the advantages and disadvantages of various approaches to produce such products. The challenges present in the production of lignin-based flocculants, adsorbents, and dispersants and possible scenarios to overcome these challenges for commercial use of these products in industry are discussed.

The particulate matter dispersion studies from a local palm oil mill

International Nuclear Information System (INIS)

Abdullah, L.C.; Wong, L. L.; Amnorzahira, A.; Sa'ari, M.; Abdul Rashid, M. S.; Salmiaton Ali

2006-01-01

The appearance of industrial emissions and the degradation of scenic vistas are two characteristics of air pollution that humans object. Reduction in visibility suggests worsening pollution levels. The emissions from mobile source and stationary source are the major source of air pollutions contribution in Malaysia. Suspended particulate matter (SPM). The consequence of increasing the particulate concentrations, the particulate matter dissolves with vapour and grows into droplets when the humidity exceeds approximately 70% and causing opaque situation know as haze. This work focuses on the dispersion particulate matter from palm oil mill. The data obtained serves the purpose of modeling the transport of particulate matter for obtaining permits and prevention of significant deterioration (PSD) to the environment. Gaussian Plume Model from a point source, subject to various atmospheric conditions is used to calculate particulate matter concentration then display the distribution of plume dispersion using geographic information system (GIS). The calculated particulate matter concentration is evaluated using Transilient Matrice function. Atmospheric Stability, mixing height, wind direction, wind speed, natural and artificial features play an important role in dispersion process. High concentration area exhibits immediately under prevailing wind direction. (Author)

Diffusion and sorption in particles and two-dimensional dispersion in a porous media

International Nuclear Information System (INIS)

Rasmuson, A.

1980-01-01

A solution of the two-dimensional differential equation of dispersion from a disk source, coupled with a differential equation of diffusion and sorption in particles, is developed. The solution is obtained by the successive use of the Laplace and the Hankel transforms and is given in the form of an infinite double-integral. If the lateral dispersion is negligible, the solution is shown to simplify to a solution presented earlier. Dimensionless quantities are introduced. A steady-state condition is obtained after long time. This is investigated in some detail. An expression is derived for the highest concentration which may be expected at a point in space. An important relation is obtained when longitudinal dispersion is neglected. The solution for any value of the lateral dispersion coefficient and radial distance from the source is then obtained by simple multiplication of a solution for no lateral dispersion with the steady-state value. A method for integrating the infinite double integral is given. Some typical examples are shown. (Auth.)

Debris Dispersion Model Using Java 3D

Science.gov (United States)

Thirumalainambi, Rajkumar; Bardina, Jorge

2004-01-01

This paper describes web based simulation of Shuttle launch operations and debris dispersion. Java 3D graphics provides geometric and visual content with suitable mathematical model and behaviors of Shuttle launch. Because the model is so heterogeneous and interrelated with various factors, 3D graphics combined with physical models provides mechanisms to understand the complexity of launch and range operations. The main focus in the modeling and simulation covers orbital dynamics and range safety. Range safety areas include destruct limit lines, telemetry and tracking and population risk near range. If there is an explosion of Shuttle during launch, debris dispersion is explained. The shuttle launch and range operations in this paper are discussed based on the operations from Kennedy Space Center, Florida, USA.

Flat super-continuum generation based on normal dispersion nonlinear photonic crystal fibre

DEFF Research Database (Denmark)

Chow, K.K.; Takushima, Y.; Lin, C.

2006-01-01

Flat super-continuum generation spanning over the whole telecommunication band using a passively modelocked fibre laser source at 1550 nm together with a dispersion-flattened nonlinear photoinc crystal fibre is demonstrated. Since the pulses propagate in the normal dispersion regime of the fibre...

A recent source modification for noble gases at the Los Alamos on-line mass analysis facility

International Nuclear Information System (INIS)

Balestrini, S.J.; Forman, L.

1976-01-01

The Los Alamos on-line mass analysis experiment at the Godiva-IV burst reactor facility has been modified to determine independent fission yields of noble gases. The gases are released from a stearate target and ionization by electron bombardment. The distance traveled by the gases from the target to the ionization chamber is 20 cm. The efficiency of the electron bombardment source is lower than that of the surface ionization source that was employed to measure the yields of Rb and Cs. But this effect is compensated by the larger quantity of target metal that is possible when using a stearate target. (Auth.)

Turbulent dispersivity under conditions relevant to airborne disease transmission between laboratory animals

Science.gov (United States)

Halloran, Siobhan; Ristenpart, William

2013-11-01

Virologists and other researchers who test pathogens for airborne disease transmissibility often place a test animal downstream from an inoculated animal and later determine whether the test animal became infected. Despite the crucial role of the airflow in pathogen transmission between the animals, to date the infectious disease community has paid little attention to the effect of airspeed or turbulent intensity on the probability of transmission. Here we present measurements of the turbulent dispersivity under conditions relevant to experimental tests of airborne disease transmissibility between laboratory animals. We used time lapse photography to visualize the downstream transport and turbulent dispersion of smoke particulates released from a point source downstream of an axial fan, thus mimicking the release and transport of expiratory aerosols exhaled by an inoculated animal. We show that for fan-generated turbulence the plume width is invariant with the mean airspeed and, close to the point source, increases linearly with downstream position. Importantly, the turbulent dispersivity is insensitive to the presence of meshes placed downstream from the point source, indicating that the fan length scale dictates the turbulent intensity and corresponding dispersivity.

Resistively detected NMR line shapes in a quasi-one-dimensional electron system

Science.gov (United States)

Fauzi, M. H.; Singha, A.; Sahdan, M. F.; Takahashi, M.; Sato, K.; Nagase, K.; Muralidharan, B.; Hirayama, Y.

2017-06-01

We observe variation in the resistively detected nuclear magnetic resonance (RDNMR) line shapes in quantum Hall breakdown. The breakdown occurs locally in a gate-defined quantum point contact (QPC) region. Of particular interest is the observation of a dispersive line shape occurring when the bulk two-dimensional electron gas (2DEG) set to νb=2 and the QPC filling factor to the vicinity of νQPC=1 , strikingly resemble the dispersive line shape observed on a 2D quantum Hall state. This previously unobserved line shape in a QPC points to a simultaneous occurrence of two hyperfine-mediated spin flip-flop processes within the QPC. Those events give rise to two different sets of nuclei polarized in the opposite direction and positioned at a separate region with different degrees of electronic spin polarization.

New Stokes' line in WKB theory

International Nuclear Information System (INIS)

Berk, H.L.; Nevins, W.M.; Roberts, K.V.

1982-01-01

The WKB theory for differential equations of arbitrary order or integral equations in one dimension is investigated. The rules previously stated for the construction of Stokes' lines for Nth-order differential equations, N> or =3, or integral equations are found to be incomplete because these rules lead to asymptotic forms of the solutions that depend on path. This paradox is resolved by the demonstration that new Stokes' lines can arise when previously defined Stokes' lines cross. A new formulation of the WKB problem is given to justify the new Stokes' lines. With the new Stokes' lines, the asymptotic forms can be shown to be independent of path. In addition, the WKB eigenvalue problem is formulated, and the global dispersion relation is shown to be a functional of loop integrals of the action

Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-12-31

This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-12-31

This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

Experimental testing of the dispersion law of ultracold neutrons

International Nuclear Information System (INIS)

Bondarenko, I.V.; Krasnoperov, A.V.; Frank, A.I.; Geltenbort, P.; Hoghoj, P.; Klein, A.G.; Cimmino, A.; Masalovich, S.V.; Nosov, V.G.

1998-01-01

Experiment on testing the generally accepted laws on ultracold neutron dispersion is described. The experiment is based on search of displacement lines of a neutron interference filter resonance by variation of neutrons rapidity component, parallel to the filter surface. The first results testify to the presence of statistically meaningful effect

Dispersal Kernel Determines Symmetry of Spread and Geographical Range for an Insect

International Nuclear Information System (INIS)

Holland, J.D.

2009-01-01

The distance from a source patch that dispersing insects reach depends on the number of dispersers, or random draws from a probability density function called a dispersal kernel, and the shape of that kernel. This can cause asymmetrical dispersal between habitat patches that produce different numbers of dispersers. Spatial distributions based on these dynamics can explain several ecological patterns including mega populations and geographic range boundaries. I hypothesized that a locally extirpated long horned beetle, the sugar maple borer, has a new geographical range shaped primarily by probabilistic dispersal distances. I used data on occurrence from Ontario, Canada to construct a model of geographical range in Indiana, USA based on maximum dispersal distance scaled by habitat area. This model predicted the new range boundary within 500 m very accurately. This beetle may be an ideal organism for exploring spatial dynamics driven by dispersal.

Dispersal of arbuscular mycorrhizal fungi and plants during succession

Science.gov (United States)

García de León, David; Moora, Mari; Öpik, Maarja; Jairus, Teele; Neuenkamp, Lena; Vasar, Martti; Bueno, C. Guillermo; Gerz, Maret; Davison, John; Zobel, Martin

2016-11-01

Arbuscular mycorrhizal (AM) fungi are important root symbionts that enhance plant nutrient uptake and tolerance to pathogens and drought. While the role of plant dispersal in shaping successional vegetation is well studied, there is very little information about the dispersal abilities of AM fungi. We conducted a trap-box experiment in a recently abandoned quarry at 10 different distances from the quarry edge (i.e. the potential propagule source) over eleven months to assess the short term, within-year, arrival of plant and AM fungal assemblages and hence their dispersal abilities. Using DNA based techniques we identified AM fungal taxa and analyzed their phylogenetic diversity. Plant diversity was determined by transporting trap soil to a greenhouse and identifying emerging seedlings. We recorded 30 AM fungal taxa. These contained a high proportion of ruderal AM fungi (30% of taxa, 79% of sequences) but the richness and abundance of AM fungi were not related to the distance from the presumed propagule source. The number of sequences of AM fungi decreased over time. Twenty seven plant species (30% of them ruderal) were recorded from the soil seed traps. Plant diversity decreased with distance from the propagule source and increased over time. Our data show that AM fungi with ruderal traits can be fast colonizers of early successional habitats.

Study of the dispersion phenomena connected with the absorption by recoilless nuclear resonance fluorescence; Etude des phenomenes de dispersion lies a l'absorption resonnante sans recul des noyaux atomiques

Energy Technology Data Exchange (ETDEWEB)

Imbert, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-12-01

In nuclear resonance fluorescence as in the optical field abnormal dispersion curves are related to the absorption lines. It is possible, by using quadrupolar or magnetic splitting of the line in the case of recoilless resonance fluorescence (Moessbauer effect) to obtain differential dispersion effects between the two orthogonal linear or the two inverse circular components of the incident gamma radiation. These effects induce bi-refraction phenomena or Faraday rotation on the gamma beam, which have been studied on Fe-57 enriched absorbers. (author) [French] Comme dans le domaine optique, aux raies d'absorption de fluorescence resonnante des noyaux atomiques sont associees des courbes de dispersion anormale. Les decompositions des raies d'absorption de fluorescence resonnante sans recul (raies Moessbauer) par couplage quadrupolaire ou effet Zeeman permettent d'obtenir des effets dispersifs differentiels entre composantes lineaires orthogonales ou circulaires inverses du rayonnement gamma incident. Ces effets se traduisent par des phenomenes de birefringence ou de rotation Faraday, qui ont pu etre etudies sur des milieux enrichis en fer-57. (auteur)

DNA Fingerprinting Validates Seed Dispersal Curves from Observational Studies in the Neotropical Legume Parkia

Science.gov (United States)

Heymann, Eckhard W.; Lüttmann, Kathrin; Michalczyk, Inga M.; Saboya, Pedro Pablo Pinedo; Ziegenhagen, Birgit; Bialozyt, Ronald

2012-01-01

Background Determining the distances over which seeds are dispersed is a crucial component for examining spatial patterns of seed dispersal and their consequences for plant reproductive success and population structure. However, following the fate of individual seeds after removal from the source tree till deposition at a distant place is generally extremely difficult. Here we provide a comparison of observationally and genetically determined seed dispersal distances and dispersal curves in a Neotropical animal-plant system. Methodology/Principal Findings In a field study on the dispersal of seeds of three Parkia (Fabaceae) species by two Neotropical primate species, Saguinus fuscicollis and Saguinus mystax, in Peruvian Amazonia, we observationally determined dispersal distances. These dispersal distances were then validated through DNA fingerprinting, by matching DNA from the maternally derived seed coat to DNA from potential source trees. We found that dispersal distances are strongly right-skewed, and that distributions obtained through observational and genetic methods and fitted distributions do not differ significantly from each other. Conclusions/Significance Our study showed that seed dispersal distances can be reliably estimated through observational methods when a strict criterion for inclusion of seeds is observed. Furthermore, dispersal distances produced by the two primate species indicated that these primates fulfil one of the criteria for efficient seed dispersers. Finally, our study demonstrated that DNA extraction methods so far employed for temperate plant species can be successfully used for hard-seeded tropical plants. PMID:22514748

Equivalent circuit of a coaxial-line-based nozzleless microwave 915 MHz plasma source

International Nuclear Information System (INIS)

Miotk, R; Jasiński, M; Mizeraczyk, J

2016-01-01

This paper presents a new concept of an equivalent circuit of a microwave plasma source (MPS) used for gas treatment. The novelty of presented investigations is the use of the Weissfloch circuit as equivalent of an area of waveguide discontinuity in the MPS which is a result of entering a coaxial-line structure. Furthermore, in this area the microwave discharge is generated. Verification of the proposed method was carried out. The proposed equivalent circuit enabled calculating the MPS tuning characteristics and comparing them with those measured experimentally. This process allowed us to determine the impedance Z_P ofplasma in the MPS. (paper)

Noise Sources, Effects and Countermeasures in Narrowband Power-Line Communications Networks: A Practical Approach

Directory of Open Access Journals (Sweden)

Gregorio López

2017-08-01

Full Text Available The integration of Distributed Generation, Electric Vehicles, and storage without compromising the quality of the power delivery requires the deployment of a communications overlay that allows monitoring and controlling low voltage networks in almost real time. Power Line Communications are gaining momentum for this purpose since they present a great trade-off between economic and technical features. However, the power lines also represent a harsh communications medium which presents different problems such as noise, which is indeed affected by Distributed Generation, Electric Vehicles, and storage. This paper provides a comprehensive overview of the types of noise that affects Narrowband Power Line Communications, including normative noises, noises coming from common electronic devices measured in actual operational power distribution networks, and noises coming from photovoltaic inverters and electric vehicle charging spots measured in a controlled environment. The paper also reviews several techniques to mitigate the effects of noise, paying special attention to passive filtering, as for being one of the most widely used solution to avoid this kind of problems in the field. In addition, the paper presents a set of tests carried out to evaluate the impact of some representative noises on Narrowband Power Line Communications network performance, as well as the effectiveness of different passive filter configurations to mitigate such an impact. In addition, the considered sources of noise can also bring value to further improve PLC communications in the new scenarios of the Smart Grid as an input to theoretical models or simulations.

A fast and simple approach for the estimation of a radiological source from localised measurements after the explosion of a radiological dispersal device

International Nuclear Information System (INIS)

Urso, L.; Kaiser, J.C.; Woda, C.; Helebrant, J.; Hulka, J.; Kuca, P.; Prouza, Z.

2014-01-01

After an explosion of a radiological dispersal device, decision-makers need to implement countermeasures as soon as possible to minimise the radiation-induced risks to the population. In this work, the authors present a tool, which can help providing information about the approximate size of source term and radioactive contamination based on a Gaussian Plume model with the use of available measurements for liquid or aerosolised radioactivity. For two-field tests, the source term and spatial distribution of deposited radioactivity are estimated. A sensitivity analysis of the dependence on deposition velocity is carried out. In case of weak winds, a diffusive process along the wind direction is retained in the model. (authors)

Production of Flocculants, Adsorbents, and Dispersants from Lignin

Directory of Open Access Journals (Sweden)

Jiachuan Chen

2018-04-01

Full Text Available Currently, lignin is mainly produced in pulping processes, but it is considered as an under-utilized chemical since it is being mainly used as a fuel source. Lignin contains many hydroxyl groups that can participate in chemical reactions to produce value-added products. Flocculants, adsorbents, and dispersants have a wide range of applications in industry, but they are mainly oil-based chemicals and expensive. This paper reviews the pathways to produce water soluble lignin-based flocculants, adsorbents, and dispersants. It provides information on the recent progress in the possible use of these lignin-based flocculants, adsorbents, and dispersants. It also critically discusses the advantages and disadvantages of various approaches to produce such products. The challenges present in the production of lignin-based flocculants, adsorbents, and dispersants and possible scenarios to overcome these challenges for commercial use of these products in industry are discussed.

New test for oil soluble/water dispersible gas pipeline inhibitors

Energy Technology Data Exchange (ETDEWEB)

Stegmann, D.W.; Asperger, R.G.

1987-01-01

The wheel test provides good mixing of the condensate and water phases, the coupons are exposed to both phases. Therefore, the wheel test cannot distinguish between inhibitors that need continuous mixing of the these phases to maintain a water dispersion of the inhibitor and inhibitors that will self disperse into the water. This concept becomes important for pipelines in stratified flow where the water can settle out. In these cases with low turbulence, the inhibitor must self disperse into the water to be effective. The paper describes a test method to measure the effectiveness of an inhibitor and its ability to self disperse. The effectiveness of several inhibitors as predicted by the new test method is discussed relative to data from the wheel test and breaker tests. Field performance of these inhibitors in a gas gathering line, with liquids in stratified flow, are cities and compared with the results of the various laboratory tests.

Assessment of the use of dispersants on oil spills in California marine waters

International Nuclear Information System (INIS)

Trudel, K.; Ross, S.; Belore, R.; Buffington, S.; Ogawa, C.; Panzer, D.

2002-01-01

The technical issues regarding the use of dispersants to clean up oil spills from offshore production sources and transportation sources in California were assessed in this study which examined both operational and environmental issues. The operational issues included the dispersibility of produced and imported oils, along with the capabilities of California response resources to deal with typical spills and limiting environmental impacts to offshore environments. The environmental issues include the risks associated with typical spills and potential net environmental benefit of chemically dispersing oil spills. Most crude oils produced offshore California are heavy and border on the undispersable range, but the imported crudes are somewhat lighter. Modeling has shown that most produced oils and some imported oils emulsify quickly and weather more quickly to the point where they are no longer dispersible. There is a very narrow window of time for chemical dispersions to be used effectively. The net environmental benefit analysis demonstrates that the use of dispersants lessens the total environmental impact of spill scenarios. It was emphasized that it is necessary to act quickly if chemical dispersion is to be effective. Rapid response strategies are needed, including locally based vessel and helicopter spraying systems. 19 refs., 8 tabs., 1 fig

Enabling On-Line Deliberation and Collective Decision-Making through Large-Scale Argumentation: A New Approach to the Design of an Internet-Based Mass Collaboration Platform

OpenAIRE

Luca Iandoli; Mark Klein; Giuseppe Zollo

2009-01-01

The successful emergence of on-line communities, such as open source software and Wikipedia, seems due to an effective combination of intelligent collective behavior and internet capabilities However, current internet technologies, such as forum, wikis and blogs appear to be less supportive for knowledge organization and consensus formation. In particular very few attempts have been done to support large, diverse, and geographically dispersed groups to systematically explore and come to decis...

On-line Field Measurements of Speciated PM1 Emission Factors from Common South Asian Combustion Sources

Science.gov (United States)

DeCarlo, P. F.; Goetz, J. D.; Giordano, M.; Stockwell, C.; Maharjan, R.; Adhikari, S.; Bhave, P.; Praveen, P. S.; Panday, A. K.; Jayarathne, T. S.; Stone, E. A.; Yokelson, R. J.

2017-12-01

Characterization of aerosol emissions from prevalent but under sampled combustion sources in South Asia was performed as part of the Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) in April 2015. Targeted emission sources included cooking stoves with a variety of solid fuels, brick kilns, garbage burning, crop-residue burning, diesel irrigation pumps, and motorcycles. Real-time measurements of submicron non-refractory particulate mass concentration and composition were obtained using an Aerodyne mini Aerosol Mass Spectrometer (mAMS). Speciated PM1 mass emission factors were calculated for all particulate species (e.g. organics, sulfates, nitrates, chlorides, ammonium) and for each source type using the carbon mass balance approach. Size resolved emission factors were also acquired using a novel high duty cycle particle time-of-flight technique (ePTOF). Black carbon and brown carbon absorption emission factors and absorption Angström exponents were measured using filter loading and scattering corrected attenuation at 370 nm and 880 nm with a dual spot aethalometer (Magee Scientific AE-33). The results indicate that open garbage burning is a strong emitter of organic aerosol, black carbon, and internally mixed particle phase hydrogen chloride (HCl). Emissions of HCl were attributed to the presence chlorinated plastics. The primarily coal fired brick kilns were found to be large emitters of sulfate but large differences in the organic and light absorbing component of emissions were observed between the two kiln types investigated (technologically advanced vs. traditional). These results, among others, bring on-line and field-tested aerosol emission measurements to an area of atmoshperic research dominated by off-line or laboratory based measurements.

Principal sources and dispersal patterns of suspended particulate matter in nearshore surface waters of the northeast Pacific Ocean and the Hawaiian Islands

Science.gov (United States)

Carlson, P. R. (Principal Investigator); Conomos, T. J.; Janda, R. J.; Peterson, D. H.

1973-01-01

The author has identified the following significant results. ERTS-1 multispectral scanner imagery of the nearshore surface waters of the Northeast Pacific Ocean is proving to be a useful tool for determining source and dispersal of suspended particulate matter. The principal sources of the turbid water, seen best on the green and red bands, are river and stream effluents and actively eroding coastlines; secondary sources are waste effluents and production of planktonic organisms, but these may sometimes be masked by the very turbid plumes of suspended sediment being discharged into the nearshore zone during times of high river discharge. The configuration and distribution of the plumes of turbid water also can be used to infer near-surface current directions. Comparison of imagery of the nearshore water off the northern California coast from October 1972 and January 1973 shows a reversal of the near-surface currents, from predominantly south-setting in the fall (California Current) to north-setting in the winter (Davidson Current).

A hybrid plume model for local-scale dispersion

Energy Technology Data Exchange (ETDEWEB)

Nikmo, J.; Tuovinen, J.P.; Kukkonen, J.; Valkama, I.

1997-12-31

The report describes the contribution of the Finnish Meteorological Institute to the project `Dispersion from Strongly Buoyant Sources`, under the `Environment` programme of the European Union. The project addresses the atmospheric dispersion of gases and particles emitted from typical fires in warehouses and chemical stores. In the study only the `passive plume` regime, in which the influence of plume buoyancy is no longer important, is addressed. The mathematical model developed and its numerical testing is discussed. The model is based on atmospheric boundary-layer scaling theory. In the vicinity of the source, Gaussian equations are used in both the horizontal and vertical directions. After a specified transition distance, gradient transfer theory is applied in the vertical direction, while the horizontal dispersion is still assumed to be Gaussian. The dispersion parameters and eddy diffusivity are modelled in a form which facilitates the use of a meteorological pre-processor. Also a new model for the vertical eddy diffusivity (K{sub z}), which is a continuous function of height in the various atmospheric scaling regions is presented. The model includes a treatment of the dry deposition of gases and particulate matter, but wet deposition has been neglected. A numerical solver for the atmospheric diffusion equation (ADE) has been developed. The accuracy of the numerical model was analysed by comparing the model predictions with two analytical solutions of ADE. The numerical deviations of the model predictions from these analytic solutions were less than two per cent for the computational regime. The report gives numerical results for the vertical profiles of the eddy diffusivity and the dispersion parameters, and shows spatial concentration distributions in various atmospheric conditions 39 refs.

Cole-Cole Measurement of Dispersion Properties for Quality Evaluation of Red Wine

Science.gov (United States)

Watanabe, Kota; Taka, Yoshinori; Fujiwara, Osamu

2009-01-01

In order to evaluate the quality of red wine, measurement of the complex relative permittivity was conducted in the frequency range from 100 MHz to 40 GHz with a network analyzer. Results showed that the Cole-Cole plot of red wine consists of a semicircle at frequencies above 1 GHz and a straight line at frequencies below 1 GHz, which come from the dispersion properties for the water solution of alcohol and ingredients peculiar to red wine, respectively. Based on the Cole-Cole plots measured for seven kinds of red wines made from the same brand of Merlot in different production years, we estimated Debye dispersion parameters to reveal that the alcohol concentration and ingredient property can simultaneously be evaluated from the parameters for the semicircle and straight line, respectively.

WEAK LINE QUASARS AT HIGH REDSHIFT: EXTREMELY HIGH ACCRETION RATES OR ANEMIC BROAD-LINE REGIONS?

International Nuclear Information System (INIS)

Shemmer, Ohad; Trakhtenbrot, Benny; Netzer, Hagai; Anderson, Scott F.; Brandt, W. N.; Schneider, Donald P.; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Lira, Paulina; Plotkin, Richard M.; Richards, Gordon T.; Strauss, Michael A.

2010-01-01

We present Gemini-North K-band spectra of two representative members of the class of high-redshift quasars with exceptionally weak rest-frame ultraviolet emission lines (WLQs), SDSS J114153.34+021924.3 at z = 3.55 and SDSS J123743.08+630144.9 at z = 3.49. In both sources, we detect an unusually weak broad Hβ line and place tight upper limits on the strengths of their [O III] lines. Virial, Hβ-based black hole mass determinations indicate normalized accretion rates of L/L Edd =0.4 for these sources, which is well within the range observed for typical quasars with similar luminosities and redshifts. We also present high-quality XMM-Newton imaging spectroscopy of SDSS J114153.34+021924.3 and find a hard-X-ray photon index of Γ = 1.91 +0.24 -0.22 , which supports the virial L/L Edd determination in this source. Our results suggest that the weakness of the broad emission lines in WLQs is not a consequence of an extreme continuum-emission source but instead due to abnormal broad emission line region properties.

NOISY DISPERSION CURVE PICKING (NDCP): a Matlab friendly suite package for fully control dispersion curve picking

Science.gov (United States)

Granados, I.; Calo, M.; Ramos, V.

2017-12-01

We developed a Matlab suite package (NDCP, Noisy Dispersion Curve Picking) that allows a full control over parameters to identify correctly group velocity dispersion curves in two types of datasets: correlograms between two stations or surface wave records from earthquakes. Using the frequency-time analysis (FTAN), the procedure to obtain the dispersion curves from records with a high noise level becomes difficult, and sometimes, the picked curve result in a misinterpreted character. For correlogram functions, obtained with cross-correlation of noise records or earthquake's coda, a non-homogeneous noise sources distribution yield to a non-symmetric Green's function (GF); to retrieve the complete information contained in there, NDCP allows to pick the dispersion curve in the time domain both in the causal and non-causal part of the GF. Then the picked dispersion curve is displayed on the FTAN diagram to in order to check if it matches with the maximum of the signal energy avoiding confusion with overtones or spike of noise. To illustrate how NDCP performs, we show exemple using: i) local correlograms functions obtained from sensors deployed into a volcanic caldera (Los Humeros, in Puebla, Mexico), ii) regional correlograms functions between two stations of the National Seismological Service (SSN, Servicio Sismológico Nacional in Spanish), and iii) surface wave seismic record for an earthquake located in the Pacific Ocean coast of Mexico and recorded by the SSN. This work is supported by the GEMEX project (Geothermal Europe-Mexico consortium).

Distinct sources of particles near the cusp and the dusk flank of the magnetosphere

Science.gov (United States)

Escoubet, C. P.; Grison, B.; Berchem, J.; Trattner, K. J.; Lavraud, B.; Pitout, F.; Soucek, J.; Richard, R. L.; Laakso, H. E.; Masson, A.; Dunlop, M.; Dandouras, I. S.; Rème, H.; Fazakerley, A. N.; Daly, P. W.

2015-12-01

At the magnetopause, the location of the magnetic reconnection sites depends on the orientation of the interplanetary magnetic field (IMF) in the solar wind: on the dayside magnetosphere for an IMF southward, on the lobes for an IMF northward and on the flanks for an IMF in the East-West direction. Since most of observations of reconnection events have sampled a limited region of space simultaneously it is still not yet know if the reconnection line is extended over large regions of the magnetosphere or if is patchy and made of many reconnection lines. We report a Cluster crossing on 5 January 2002 near the exterior cusp on the southern dusk side where we observe multiple sources of reconnection/injections. The IMF was mainly azimuthal (IMF-By around -5 nT), the solar wind speed lower than usual around 280 km/s with the density of order 5 cm-3. The four Cluster spacecraft had an elongated configuration near the magnetopause. C4 was the first spacecraft to enter the cusp around 19:52:04 UT, followed by C2 at 19:52:35 UT, C1 at 19:54:24 UT and C3 at 20:13:15 UT. C4 and C1 observed two ion energy dispersions at 20:10 UT and 20:40 UT and C3 at 20:35 UT and 21:15 UT. Using the time of flight technique on the upgoing and downgoing ions, which leads to energy dispersions, we obtain distances of the ion sources between 14 and 20 RE from the spacecraft. The slope of the ion energy dispersions confirmed these distances. Using Tsyganenko model, we find that these sources are located on the dusk flank, past the terminator. The first injection by C3 is seen at approximately the same time as the 2nd injection on C1 but their sources at the magnetopause were separated by more than 7 RE. This would imply that two distinct sources were active at the same time on the dusk flank of the magnetosphere. In addition, a flow reversal was observed at the magnetopause on C4 which would be an indication that reconnection is also taking place near the exterior cusp quasi-simultaneously. A

A model for short and medium range dispersion of radionuclides released to the atmosphere

International Nuclear Information System (INIS)

Clarke, R.H.

1979-09-01

A Working Group was established to give practical guidance on the estimation of the dispersion of radioactive releases to the atmosphere. The dispersion is estimated in the short and medium range, that is from about 100 m to a few tens of kilometres from the source, and is based upon a Gaussian plume model. A scheme is presented for categorising atmospheric conditions and values of the associated dispersion parameters are given. Typical results are presented for releases in specific meteorological conditions and a scheme is included to allow for durations of release of up to 24 hours. Consideration has also been given to predicting longer term average concentrations, typically annual averages, and results are presented which facilitate site specific calculations. The results of the models are extended to 100 km from the source, but the increasing uncertainty with which results may be predicted beyond a few tens of kilometres from the source is emphasised. Three technical appendices provide some of the rationale behind the decisions made in adopting the various models in the proposed dispersion scheme. (author)

GPS tracking of non-breeding ravens reveals the importance of anthropogenic food sources during their dispersal in the Eastern Alps.

Science.gov (United States)

Loretto, Matthias-Claudio; Schuster, Richard; Bugnyar, Thomas

2016-08-01

In many songbirds, the space use of breeders is well studied but poorly understood for non-breeders. In common ravens, some studies of non-breeders indicate high vagrancy with large individual differences in home range size, whereas others show that up to 40% of marked non-breeders can be regularly observed at the same anthropogenic food source over months to years. The aim of this study was to provide new insights on ravens' behavior during dispersal in the Eastern Alps. We deployed Global Positioning System (GPS) loggers on 10 individuals to gather accurate spatial and temporal information on their movements to quantify: 1) the dimension of the birds' space use (home range size with seasonal effects and daily/long-term travel distances), 2) how long they stayed in a dispersal stage of wandering as opposed to settling temporarily, and 3) their destination of movements. We recorded movements of up to 40 km per hour, more than 160 km within 1 day and more than 11,000 km within 20 months, indicating high vagrancy. Switching frequently between temporarily settling and travelling large distances in short time intervals leads to extensive home ranges, which also explains and combines the different findings in the literature. The destinations are rich anthropogenic food sources, where the birds spent on average 75% of their time. We discuss how ravens may find these "feeding hot spots" and which factors may influence their decision to stay/leave a site. The strong dependence on anthropogenic resources found in this population may have implications for site management and conservation issues.

Humans as long-distance dispersers of rural plant communities.

Directory of Open Access Journals (Sweden)

Alistair G Auffret

Full Text Available Humans are known for their capacity to disperse organisms long distances. Long-distance dispersal can be important for species threatened by habitat destruction, but research into human-mediated dispersal is often focused upon few and/or invasive species. Here we use citizen science to identify the capacity for humans to disperse seeds on their clothes and footwear from a known species pool in a valuable habitat, allowing for an assessment of the fraction and types of species dispersed by humans in an alternative context. We collected material from volunteers cutting 48 species-rich meadows throughout Sweden. We counted 24,354 seeds of 197 species, representing 34% of the available species pool, including several rare and protected species. However, 71 species (36% are considered invasive elsewhere in the world. Trait analysis showed that seeds with hooks or other appendages were more likely to be dispersed by humans, as well as those with a persistent seed bank. More activity in a meadow resulted in more dispersal, both in terms of species and representation of the source communities. Average potential dispersal distances were measured at 13 km. We consider humans capable seed dispersers, transporting a significant proportion of the plant communities in which they are active, just like more traditional vectors such as livestock. When rural populations were larger, people might have been regular and effective seed dispersers, and the net rural-urban migration resulting in a reduction in humans in the landscape may have exacerbated the dispersal failure evident in declining plant populations today. With the fragmentation of habitat and changes in land use resulting from agricultural change, and the increased mobility of humans worldwide, the dispersal role of humans may have shifted from providers of regular local and landscape dispersal to providers of much rarer long-distance and regional dispersal, and international invasion.

Uranium Dispersion and Dosimetry (UDAD) Code

International Nuclear Information System (INIS)

Momeni, M.H.; Yuan, Y.; Zielen, A.J.

1979-05-01

The Uranium Dispersion and Dosimetry (UDAD) Code provides estimates of potential radiation exposure to individuals and to the general population in the vicinity of a uranium processing facility. The UDAD Code incorporates the radiation dose from the airborne release of radioactive materials, and includes dosimetry of inhalation, ingestion, and external exposures. The removal of raioactive particles from a contaminated area by wind action is estimated, atmospheric concentrations of radioactivity from specific sources are calculated, and source depletion as a result of deposition, fallout, and ingrowth of radon daughters are included in a sector-averaged Gaussian plume dispersion model. The average air concentration at any given receptor location is assumed to be constant during each annual release period, but to increase from year to year because of resuspension. Surface contamination and deposition velocity are estimated. Calculation of the inhalation dose and dose rate to an individual is based on the ICRP Task Group Lung Model. Estimates of the dose to the bronchial epithelium of the lung from inhalation of radon and its short-lived daughters are calculated based on a dose conversion factor from the BEIR report. External radiation exposure includes radiation from airborne radionuclides and exposure to radiation from contaminated ground. Terrestrial food pathways include vegetation, meat, milk, poultry, and eggs. Internal dosimetry is based on ICRP recommendations. In addition, individual dose commitments, population dose commitments, and environmental dose commitments are computed. This code also may be applied to dispersion of any other pollutant

Modeling of dispersion engineered chalcogenide rib waveguide for ultraflat mid-infrared supercontinuum generation in all-normal dispersion regime

Science.gov (United States)

Ahmad, H.; Karim, M. R.; Rahman, B. M. A.

2018-03-01

A rigorous numerical investigation has been carried out through dispersion engineering of chalcogenide rib waveguide for near-infrared to mid-infrared ultraflat broadband supercontinuum generation in all-normal group-velocity dispersion regime. We propose a novel design of a 1-cm-long air-clad rib waveguide which is made from {Ge}_{11.5} {As}_{24} {Se}_{64.5} chalcogenide glass as the core with either silica or {Ge}_{11.5} {As}_{24} {S}_{64.5} chalcogenide glass as a lower cladding separately. A broadband ultraflat supercontinuum spanning from 1300 to 1900 nm could be generated when pumped at 1.55 μ {m} with a low input peak power of 100 W. Shifting the pump to 2 μ {m}, the supercontinuum spectra extended in the mid-infrared region up to 3400 nm with a moderate-input peak power of 500 W. To achieve further extension in mid-infrared, we excite our optimized rib waveguide in both the anomalous and all-normal dispersion pumping regions at 3.1 μ {m} with a largest input peak power of 3 kW. In the case of anomalous dispersion region pumping, numerical analysis shows that supercontinuum spectrum can be extended in the mid-infrared up to 10 μ {m}, although this contains high spectral amplitude fluctuations over the entire bandwidth which limits the supercontinuum sources in the field of high precision measurement applications. On the other hand, by optimizing a rib waveguide geometry for pumping in all-normal dispersion region, we are able to generate a smooth and flat-top coherent supercontinuum spectrum with a moderate bandwidth spanning the wavelength range 2-5.5 μ {m} with less than 5 dB spectral fluctuation over the entire output bandwidth. Our proposed design is highly suitable for making on-chip SC light sources for a variety of applications such as biomedical imaging, and environmental and industrial sensing in the mid-infrared region.

Identifying sources of methane sampled in the Arctic using δ13C in CH4 and Lagrangian particle dispersion modelling.

Science.gov (United States)

Cain, Michelle; France, James; Pyle, John; Warwick, Nicola; Fisher, Rebecca; Lowry, Dave; Allen, Grant; O'Shea, Sebastian; Illingworth, Samuel; Jones, Ben; Gallagher, Martin; Welpott, Axel; Muller, Jennifer; Bauguitte, Stephane; George, Charles; Hayman, Garry; Manning, Alistair; Myhre, Catherine Lund; Lanoisellé, Mathias; Nisbet, Euan

2016-04-01

An airmass of enhanced methane was sampled during a research flight at ~600 m to ~2000 m altitude between the North coast of Norway and Svalbard on 21 July 2012. The largest source of methane in the summertime Arctic is wetland emissions. Did this enhancement in methane come from wetland emissions? The airmass was identified through continuous methane measurements using a Los Gatos fast greenhouse gas analyser on board the UK's BAe-146 Atmospheric Research Aircraft (ARA) as part of the MAMM (Methane in the Arctic: Measurements and Modelling) campaign. A Lagrangian particle dispersion model (the UK Met Office's NAME model) was run backwards to identify potential methane source regions. This was combined with a methane emission inventory to create "pseudo observations" to compare with the aircraft observations. This modelling was used to constrain the δ13C CH4 wetland source signature (where δ13C CH4 is the ratio of 13C to 12C in methane), resulting in a most likely signature of -73‰ (±4‰7‰). The NAME back trajectories suggest a methane source region of north-western Russian wetlands, and -73‰ is consistent with in situ measurements of wetland methane at similar latitudes in Scandinavia. This analysis has allowed us to study emissions from remote regions for which we do not have in situ observations, giving us an extra tool in the determination of the isotopic source variation of global methane emissions.

Effect of tubing length on the dispersion correction of an arterially sampled input function for kinetic modeling in PET.

Science.gov (United States)

O'Doherty, Jim; Chilcott, Anna; Dunn, Joel

2015-11-01

Arterial sampling with dispersion correction is routinely performed for kinetic analysis of PET studies. Because of the the advent of PET-MRI systems, non-MR safe instrumentation will be required to be kept outside the scan room, which requires the length of the tubing between the patient and detector to increase, thus worsening the effects of dispersion. We examined the effects of dispersion in idealized radioactive blood studies using various lengths of tubing (1.5, 3, and 4.5 m) and applied a well-known transmission-dispersion model to attempt to correct the resulting traces. A simulation study was also carried out to examine noise characteristics of the model. The model was applied to patient traces using a 1.5 m acquisition tubing and extended to its use at 3 m. Satisfactory dispersion correction of the blood traces was achieved in the 1.5 m line. Predictions on the basis of experimental measurements, numerical simulations and noise analysis of resulting traces show that corrections of blood data can also be achieved using the 3 m tubing. The effects of dispersion could not be corrected for the 4.5 m line by the selected transmission-dispersion model. On the basis of our setup, correction of dispersion in arterial sampling tubing up to 3 m by the transmission-dispersion model can be performed. The model could not dispersion correct data acquired using a 4.5 m arterial tubing.

Genetic consequences of seed dispersal to sleeping trees by white-bellied spider monkeys

Science.gov (United States)

Karubian, Jordan; Ottewell, Kym; Link, Andres; Di Fiore, Anthony

2015-10-01

Frugivorous animals frequently generate clumped distributions of seeds away from source trees via 'destination-based' dispersal processes. For example, use of traditional sleeping trees by white-bellied spider monkeys Ateles belzebuth generates high densities of seeds of a preferred food source, the palm Oenocarpus bataua, at these sites. Little is known about the maternal seed source diversity and population genetic metrics of seed pools encountered at these sites. Given the repeated use of sleeping trees over time, and the fluid social organization and wide ranging movements exhibited by spider monkeys, we predicted that O. bataua seed pools beneath sleeping trees would be characterized by relatively high values of maternal seed source diversity and standard metrics of genetic diversity. Contrary to these expectations, we found relatively low average maternal seed source diversity beneath each of 6 sleeping trees we studied (weighted mean α = 3.74), but considerable variation in diversity of maternal seed sources between sleeping trees (range = 1.75-10.1) and high heterogeneity in standard genetic diversity measures between sleeping trees. There was no evidence for overlap in maternal seed sources between sleeping tree sites (δ = 1.0), resulting in significant genetic differentiation (Fst = 0.055-0.319) between these sites. Observed variation between sleeping trees could not be explained by the number of individual spider monkeys whose core home ranges included a given tree, nor by distance to a central mineral lick, a focal point of spider monkey activity. These findings suggest that spider monkey seed dispersal to sleeping trees is spatially restricted, perhaps because the animals visit sleeping trees at the end of the day and therefore only disperse O. bataua fruits that they ingest late in the day. These results add to our growing appreciation of the ways frugivore behavior mechanistically shapes seed dispersal outcomes.

Effects of three types of oil dispersants on biodegradation of dispersed crude oil in water surrounding two Persian gulf provinces.

Science.gov (United States)

Zolfaghari-Baghbaderani, Azadeh; Emtyazjoo, Mozhgan; Poursafa, Parinaz; Mehrabian, Sedigheh; Bijani, Samira; Farkhani, Daryoush; Mirmoghtadaee, Parisa

2012-01-01

To determine the most effective and biodegradable dispersant of spilled oil in water surrounding two Persian Gulf provinces. This study compared the effects of three dispersants, Pars 1, Pars 2, and Gamlen OD4000 on removal of oil in two Persian Gulf provinces' water. Overall, 16 stations were selected. Using the Well method, the growth rate of isolated bacteria and fungi was identified. To specify the growth rate of microorganisms and their usage of oil in the presence of the above-mentioned dispersants, as exclusive sources of carbon, the bacteria were grown in culture medium for 28 days at 120 rpm, 30°C, and their optical density was measured by spectrophotometry. Then, we tested biological oxygen demand (BOD) and chemical oxygen demand (COD) in microorganisms. The highest growth rate was documented for the growth of microorganisms on either Pars 1 or Pars 2 dispersants or their mixtures with oil. However, the culture having microorganisms grown on Pars 1 had higher BOD and COD than the other two dispersants (9200 and 16800 versus 500 and 960, P microorganisms grown on Pars 2 had maximum amount of BOD and COD in comparison with Pars 1 and Gamlen dispersants (7100 and 15200 versus 6000 and 10560, P < 0.05). Pars 1 and Pars 2 were the most effective dispersants with highest degradability comparing Gamlen. In each region, the most suitable compound for removing oil spill from offshores with least secondary contamination should be investigated.

Toad radiation reveals into-India dispersal as a source of endemism in the Western Ghats-Sri Lanka biodiversity hotspot

Directory of Open Access Journals (Sweden)

Bossuyt Franky

2009-06-01

Full Text Available Abstract Background High taxonomic level endemism in the Western Ghats-Sri Lanka biodiversity hotspot has been typically attributed to the subcontinent's geological history of long-term isolation. Subsequent out of – and into India dispersal of species after accretion to the Eurasian mainland is therefore often seen as a biogeographic factor that 'diluted' the composition of previously isolated Indian biota. However, few molecular studies have focussed on into-India dispersal as a possible source of endemism on the subcontinent. Using c. 6000 base pairs of mitochondrial and nuclear DNA, we investigated the evolutionary history and biogeography of true toads (Bufonidae, a group that colonized the Indian Subcontinent after the Indo-Asia collision. Results Contrary to previous studies, Old World toads were recovered as a nested clade within New World Bufonidae, indicating a single colonization event. Species currently classified as Ansonia and Pedostibes were both recovered as being non-monophyletic, providing evidence for the independent origin of torrential and arboreal ecomorphs on the Indian subcontinent and in South-East Asia. Our analyses also revealed a previously unrecognized adaptive radiation of toads containing a variety of larval and adult ecomorphs. Molecular dating estimates and biogeographic analyses indicate that the early diversification of this clade happened in the Western Ghats and Sri Lanka during the Late Oligocene to Early Miocene. Conclusion Paleoclimate reconstructions have shown that the Early Neogene of India was marked by major environmental changes, with the transition from a zonal- to the current monsoon-dominated climate. After arrival in the Western Ghats-Sri Lanka hotspot, toads diversified in situ, with only one lineage able to successfully disperse out of these mountains. Consequently, higher taxonomic level endemism on the Indian Subcontinent is not only the result of Cretaceous isolation, but also of invasion

Numerical study on flow and pollutant dispersion inside street canyons

OpenAIRE

Yunkai, Yang

2013-01-01

This thesis analyzes the characteristics of flow pattern and vehicle-emitted pollutant dispersion in roughness surface layer. In an urban environment, wind flow and transported-pollutant source interfere strongly with buildings and other roughness elements on the surface ground, which results in complex characteristics of flow pattern and pollutant dispersion in 3D circumstances. The present study intends to simplify the research domain and investigate the fundamental modeling problems that e...

Rafting rocks reveal marine biological dispersal: A case study using clasts from beach-cast macroalgal holdfasts

Science.gov (United States)

Garden, Christopher J.; Craw, Dave; Waters, Jonathan M.; Smith, Abigail

2011-12-01

Tracking and quantifying biological dispersal presents a major challenge in marine systems. Most existing methods for measuring dispersal are limited by poor resolution and/or high cost. Here we use geological data to quantify the frequency of long-distance dispersal in detached bull-kelp (Phaeophyceae: Durvillaea) in southern New Zealand. Geological resolution in this region is enhanced by the presence of a number of distinct and readily-identifiable geological terranes. We sampled 13,815 beach-cast bull-kelp plants across 130 km of coastline. Rocks were found attached to 2639 of the rafted plants, and were assigned to specific geological terranes (source regions) to quantify dispersal frequencies and distances. Although the majority of kelp-associated rock specimens were found to be locally-derived, a substantial number (4%) showed clear geological evidence of long-distance dispersal, several having travelled over 200 km from their original source regions. The proportion of local versus foreign clasts varied considerably between regions. While short-range dispersal clearly predominates, long-distance travel of detached bull-kelp plants is shown to be a common and ongoing process that has potential to connect isolated coastal populations. Geological analyses represent a cost-effective and powerful method for assigning large numbers of drifted macroalgae to their original source regions.

SREM - WRS system module number 3348 for calculating the removal flux due to point, line or disc sources

International Nuclear Information System (INIS)

Grimstone, M.J.

1978-06-01

The WRS Modular Programming System has been developed as a means by which programmes may be more efficiently constructed, maintained and modified. In this system a module is a self-contained unit typically composed of one or more Fortran routines, and a programme is constructed from a number of such modules. This report describes one WRS module, the function of which is to calculate the uncollided flux and first-collision source from a disc source in a slab geometry system, a line source at the centre of a cylindrical system or a point source at the centre of a spherical system. The information given in this manual is of use both to the programmer wishing to incorporate the module in a programme, and to the user of such a programme. (author)

Dispersion engineering of mode-locked fibre lasers

Science.gov (United States)

Woodward, R. I.

2018-03-01

Mode-locked fibre lasers are important sources of ultrashort pulses, where stable pulse generation is achieved through a balance of periodic amplitude and phase evolutions. A range of distinct cavity pulse dynamics have been revealed, arising from the interplay between dispersion and nonlinearity in addition to dissipative processes such as filtering. This has led to the discovery of numerous novel operating regimes, offering significantly improved laser performance. In this Topical Review, we summarise the main steady-state pulse dynamics reported to date through cavity dispersion engineering, including average solitons, dispersion-managed solitons, dissipative solitons, giant-chirped pulses and similaritons. Characteristic features and the stabilisation mechanism of each regime are described, supported by numerical modelling, in addition to the typical performance and limitations. Opportunities for further pulse energy scaling are discussed, in addition to considering other recent advances including automated self-tuning cavities and fluoride-fibre-based mid-infrared mode-locked lasers.

Optical spectrum of the HDE 245770 and X-ray flares of the transient sources A 0535+26

International Nuclear Information System (INIS)

Aab, O.Eh.

1985-01-01

Investigation results are presented for the optical component of the transient X-ray source A 0535+26, the Be star HDE 245770. The investigation is based on the spectrograms with dispersions 9, 14 and 28 A/mm obtained during three years with the 6-meter telescope. A list of lines and their parameters within the range lambdalambda 3450-7000 A is given. Variability of the spectrum for the three years and a violent change in the spectrum in January 1981 are noted

Modelling surface radioactive spill dispersion in the Alboran Sea

International Nuclear Information System (INIS)

Perianez, R.

2006-01-01

The Strait of Gibraltar and the Alboran Sea are the only connection between the Atlantic Ocean and the Mediterranean Sea. Intense shipping activities occur in the area, including transport of waste radionuclides and transit of nuclear submarines. Thus, it is relevant to have a dispersion model that can be used in an emergency situation after an accident, to help the decision-making process. Such dispersion model requires an appropriate description of the physical oceanography of the region of interest, with simulations of tides and residual (average) circulation. In this work, a particle-tracking dispersion model that can be used to simulate the dispersion of radionuclides in the system Strait of Gibraltar-Alboran Sea is described. Tides are simulated using a barotropic model and for the average circulation a reduced-gravity model is applied. This model is able to reproduce the main features of the Alboran circulation (the well known Western Alboran Gyre, WAG, and the coastal circulation mode). The dispersion model is run off-line, using previously computed tidal and residual currents. The contamination patch is simulated by a number of particles whose individual paths are computed; diffusion and decay being modelled using a Monte Carlo method. Radionuclide concentrations may be obtained from the density of particles per water volume unit. Results from the hydrodynamic models have been compared with observations in the area. Several examples of dispersion computations under different wind and circulation conditions are presented

Molecular line study of massive star-forming regions from the Red MSX Source survey

Science.gov (United States)

Yu, Naiping; Wang, Jun-Jie

2014-05-01

In this paper, we have selected a sample of massive star-forming regions from the Red MSX Source survey, in order to study star formation activities (mainly outflow and inflow signatures). We have focused on three molecular lines from the Millimeter Astronomy Legacy Team Survey at 90 GHz: HCO+(1-0), H13CO+(1-0) and SiO(2-1). According to previous observations, our sources can be divided into two groups: nine massive young stellar object candidates (radio-quiet) and 10 H II regions (which have spherical or unresolved radio emissions). Outflow activities have been found in 11 sources, while only three show inflow signatures in all. The high outflow detection rate means that outflows are common in massive star-forming regions. The inflow detection rate was relatively low. We suggest that this was because of the beam dilution of the telescope. All three inflow candidates have outflow(s). The outward radiation and thermal pressure from the central massive star(s) do not seem to be strong enough to halt accretion in G345.0034-00.2240. Our simple model of G318.9480-00.1969 shows that it has an infall velocity of about 1.8 km s-1. The spectral energy distribution analysis agrees our sources are massive and intermediate-massive star formation regions.

Atmospheric dispersion calculations in a low mountain area

International Nuclear Information System (INIS)

Schmid, S.

1987-01-01

The applicability of the Gaussian model for assessing the short-range environmental exposure from an emission source in a topographically inhomogeneous terrain is tested. An atmospheric dispersion model of general applicability is used, which is based on results of hydrodynamic flow models. Approaches for turbulence and radiation parameterization are tested by means of a vertically one-dimensional flow model. In order to introduce the effects of the topography in the boundary-layer simulations, the three-dimensional mesoscale model (Ulrich) is applied. The two models are verified by way of episode simulation using wind profile measurements. The differences in the models' results are to show the topographic influence. The calculated flow fields serve as input to a randomwalk model applied for calculating ground-level concentration fields in the vicinity of an emission source. The Gaussian model underestimates the pollution under stable conditions. Convectivity conditions may change the effective source hight through vertical effects caused by orography which, depending on the direction of free flow, leads to an increase or decrease of pollutant concentration at ground level. Applying the more complex dispersion model, the concentration maxima under stable conditions are closer to the source by a factor five, and under unstable conditions about one and a half times more remote. (orig./HP) [de

Estimating nitrogen loading and far-field dispersal potential from background sources and coastal finfish aquaculture: A simple framework and case study in Atlantic Canada

Science.gov (United States)

McIver, R.; Milewski, I.; Loucks, R.; Smith, R.

2018-05-01

Far-field nutrient impacts associated with finfish aquaculture have been identified as a topic of concern for regulators, managers, scientists, and the public for over two decades but disentangling aquaculture impacts from those caused by other natural and anthropogenic sources has impeded the development of monitoring metrics and management plans. We apply a bulk, steady-state nitrogen loading model (NLM) framework to estimate the annual input of Total Dissolved Nitrogen (TDN) from point and non-point sources to the watershed surrounding Port Mouton Bay, Nova Scotia (Canada). We then use the results of the NLM together with estimates of dissolved inorganic nitrogen (DIN) loading from a sea-cage trout farm in the Bay and progressive vector diagrams to illustrate potential patterns of DIN dispersal from the trout farm. Our estimated anthropogenic nitrogen contribution to Port Mouton Bay from all terrestrial and atmospheric sources is ∼211,703 kg TDN/year with atmospheric deposition accounting for almost all (98.6%). At a stocking level of ∼400,000 rainbow trout, the Port Mouton Bay sea-cage farm increases the annual anthropogenic TDN loading to the bay by 14.4% or 30,400 kg. Depending on current flow rates, nitrogen flux from the trout farm can be more than double the background concentrations of TDN near the farm site. Although it is unlikely that nitrogen loading from this single fish farm is saturating the DIN requirements of the entire bay, progressive vector diagrams suggest that the dispersal potential may be insufficient to mitigate potential symptoms of eutrophication associated with nitrogen fluxes. We present an accessible and user-friendly tool for managers to estimate baseline nutrient loading in relation to aquaculture and our use of progressive vector diagrams illustrate a practical and simple method for characterizing potential nutrient dispersal based on local conditions and spatial scales. Our study joins numerous studies which have highlighted

Effects of Three Types of Oil Dispersants on Biodegradation of Dispersed Crude Oil in Water Surrounding Two Persian Gulf Provinces

Directory of Open Access Journals (Sweden)

Azadeh Zolfaghari-Baghbaderani

2012-01-01

Full Text Available Objective. To determine the most effective and biodegradable dispersant of spilled oil in water surrounding two Persian Gulf provinces. Methods. This study compared the effects of three dispersants, Pars 1, Pars 2, and Gamlen OD4000 on removal of oil in two Persian Gulf provinces' water. Overall, 16 stations were selected. Using the Well method, the growth rate of isolated bacteria and fungi was identified. To specify the growth rate of microorganisms and their usage of oil in the presence of the above-mentioned dispersants, as exclusive sources of carbon, the bacteria were grown in culture medium for 28 days at 120 rpm, 30∘C, and their optical density was measured by spectrophotometry. Then, we tested biological oxygen demand (BOD and chemical oxygen demand (COD in microorganisms. Results. The highest growth rate was documented for the growth of microorganisms on either Pars 1 or Pars 2 dispersants or their mixtures with oil. However, the culture having microorganisms grown on Pars 1 had higher BOD and COD than the other two dispersants (9200 and 16800 versus 500 and 960, P<0.05. Mixture of oil and Pars 2 as well as oil and Pars 1 dispersants showed the highest BODs and CODs, respectively. In the Bahregan province, microorganisms grown on Pars 2 had maximum amount of BOD and COD in comparison with Pars 1 and Gamlen dispersants (7100 and 15200 versus 6000 and 10560, P<0.05. Conclusion. Pars 1 and Pars 2 were the most effective dispersants with highest degradability comparing Gamlen. In each region, the most suitable compound for removing oil spill from offshores with least secondary contamination should be investigated.

Effects of Three Types of Oil Dispersants on Biodegradation of Dispersed Crude Oil in Water Surrounding Two Persian Gulf Provinces

International Nuclear Information System (INIS)

Zolfaghari-Baghbaderani, A.; Bijani, S.; Zolfaghari-Baghbaderani, A.; Bijani, S.; Emtyazjoo, M.; Emtyazjoo, M.; Poursafa, P.; Mehrabian, S.; Farkhani, D.; Mirmoghtadaee, P.

2012-01-01

Objective. To determine the most effective and biodegradable dispersant of spilled oil in water surrounding two Persian Gulf provinces. Methods. This study compared the effects of three dispersants, Pars 1, Pars 2, and Gamlen OD4000 on removal of oil in two Persian Gulf provinces' water. Overall, 16 stations were selected. Using the Well method, the growth rate of isolated bacteria and fungi was identified. To specify the growth rate of microorganisms and their usage of oil in the presence of the above-mentioned dispersants, as exclusive sources of carbon, the bacteria were grown in culture medium for 28 days at 120 rpm, 30 C, and their optical density was measured by spectrophotometry. Then, we tested biological oxygen demand (BOD) and chemical oxygen demand (COD) in microorganisms. Results. The highest growth rate was documented for the growth of microorganisms on either Pars 1 or Pars 2 dispersants or their mixtures with oil. However, the culture having microorganisms grown on Pars 1 had higher BOD and COD than the other two dispersants (9200 and 16800 versus 500 and 960, P<0.05). Mixture of oil and Pars 2 as well as oil and Pars 1 dispersants showed the highest BODs and CODs, respectively. In the Bahregan province, microorganisms grown on Pars 2 had maximum amount of BOD and COD in comparison with Pars 1 and Gamlen dispersants (7100 and 15200 versus 6000 and 10560, P<0.05). Conclusion. Pars 1 and Pars 2 were the most effective dispersants with highest degradability comparing Gamlen. In each region, the most suitable compound for removing oil spill from off shores with least secondary contamination should be investigated.

Optics Flexibility and Dispersion Matching at Injection into the LHC

CERN Document Server

Koschik, A; Goddard, B; Kadi, Y; Kain, V; Mertens, V; Risselada, Thys

2006-01-01

The LHC requires very precise matching of transfer line and LHC optics to minimise emittance blow-up and tail repopulation at injection. The recent addition of a comprehensive transfer line collimation system to improve the protection against beam loss has created additional matching constraints and consumed a significant part of the flexibility contained in the initial optics design of the transfer lines. Optical errors, different injection configurations and possible future optics changes require however to preserve a certain tuning range. Here we present methods of tuning optics parameters at the injection point by using orbit correctors in the main ring, with the emphasis on dispersion matching. The benefit of alternative measures to enhance the flexibility is briefly discussed.

Thallium dispersal and contamination in surface sediments from South China and its source identification.

Science.gov (United States)

Liu, Juan; Wang, Jin; Chen, Yongheng; Shen, Chuan-Chou; Jiang, Xiuyang; Xie, Xiaofan; Chen, Diyun; Lippold, Holger; Wang, Chunlin

2016-06-01

Thallium (Tl) is a non-essential element in humans and it is considered to be highly toxic. In this study, the contents, sources, and dispersal of Tl were investigated in surface sediments from a riverine system (the western Pearl River Basin, China), whose catchment has been contaminated by mining and roasting of Tl-bearing pyrite ores. The isotopic composition of Pb and total contents of Tl and other relevant metals (Pb, Zn, Cd, Co, and Ni) were measured in the pyrite ores, mining and roasting wastes, and the river sediments. Widespread contamination of Tl was observed in the sediments across the river, with the highest concentration of Tl (17.3 mg/kg) measured 4 km downstream from the pyrite industrial site. Application of a modified Institute for Reference Materials and Measurement (IRMM) sequential extraction scheme in representative sediments unveiled that 60-90% of Tl and Pb were present in the residual fraction of the sediments. The sediments contained generally lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratios compared with the natural Pb isotope signature (1.2008 and 2.0766 for (206)Pb/(207)Pb and (208)Pb/(206)Pb, respectively). These results suggested that a significant fraction of non-indigenous Pb could be attributed to the mining and roasting activities of pyrite ores, with low (206)Pb/(207)Pb (1.1539) and high (208)Pb/(206)Pb (2.1263). Results also showed that approximately 6-88% of Tl contamination in the sediments originated from the pyrite mining and roasting activities. This study highlights that Pb isotopic compositions could be used for quantitatively fingerprinting the sources of Tl contamination in sediments. Copyright © 2016 Elsevier Ltd. All rights reserved.

1-D profiling using highly dispersive guided waves

Science.gov (United States)

Volker, Arno; van Zon, Tim

2014-02-01

Corrosion is one of the industries major issues regarding the integrity of assets. Currently, inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness of steel pipes. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pitch-catch configuration at the 12 o'clock position using highly dispersive guided waves. After dispersion correction the data collapses to a short pulse, any residual dispersion indicates wall loss. The phase spectrum is used to invert for the wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. The approach is evaluated on numerically simulated and on measured data. The method is intended for rapid, semi-quantitative screening of pipes.

1-D profiling using highly dispersive guided waves

International Nuclear Information System (INIS)

Volker, Arno; Zon, Tim van

2014-01-01

Corrosion is one of the industries major issues regarding the integrity of assets. Currently, inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness of steel pipes. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pitch-catch configuration at the 12 o'clock position using highly dispersive guided waves. After dispersion correction the data collapses to a short pulse, any residual dispersion indicates wall loss. The phase spectrum is used to invert for the wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. The approach is evaluated on numerically simulated and on measured data. The method is intended for rapid, semi-quantitative screening of pipes

Photonic crystal waveguides with semi-slow light and tailored dispersion properties

DEFF Research Database (Denmark)

Frandsen, Lars Hagedorn; Lavrinenko, Andrei; Fage-Pedersen, Jacob

2006-01-01

waveguide with either vanishing, positive, or negative group velocity dispersion and semi-slow light. We realize experimentally a silicon-on-insulator photonic crystal waveguide having nearly constant group velocity [similar to]c$-0$//34 in an 11-nm bandwidth below the silica-line. $CPY@2006 Optical Society...

Thermoelastic stress due to an instantaneous finite line heat source in an infinite medium

International Nuclear Information System (INIS)

Claesson, J.; Hellstroem, G.

1995-09-01

The problem originates from studies of nuclear waste repositories in rock. The problem is by superposition reduced to the case of a single, infinite, antisymmetric, instantaneous line heat source. The dimensionless problem turns out to depend on the dimensionless radial and axial coordinates only, although the original time-dependent problem contains several parameters. An exact analytical solution is derived. The solution is surprisingly handy, considering the complexity of the original problem. The stress and strain field are readily obtained from derivatives of the displacement components. These fields are studied and presented in detail. Asymptotic behaviour, field of principal stresses, regions of compression and tension, and largest values of compression and tension of the components are given as exact formulas. The solution may be used to test numerical models for coupled thermoelastic processes. It may also be used in more detailed numerical simulations of the process near the heat sources as boundary conditions to account for the three-dimensional global process. 7 refs

Assessment of impact distances for particulate matter dispersion: A stochastic approach

Energy Technology Data Exchange (ETDEWEB)

Godoy, S.M.; Mores, P.L.; Santa Cruz, A.S.M. [CAIMI - Centro de Aplicaciones Informaticas y Modelado en Ingenieria, Universidad Tecnologica Nacional-Facultad Regional Rosario, Zeballos 1341-S2000 BQA Rosario, Santa Fe (Argentina); Scenna, N.J. [CAIMI - Centro de Aplicaciones Informaticas y Modelado en Ingenieria, Universidad Tecnologica Nacional-Facultad Regional Rosario, Zeballos 1341-S2000 BQA Rosario, Santa Fe (Argentina); INGAR - Instituto de Desarrollo y Diseno (Fundacion ARCIEN - CONICET), Avellaneda 3657, S3002 GJC Santa Fe (Argentina)], E-mail: nscenna@santafe-conicet.gov.ar

2009-10-15

It is known that pollutants can be dispersed from the emission sources by the wind, or settled on the ground. Particle size, stack height, topography and meteorological conditions strongly affect particulate matter (PM) dispersion. In this work, an impact distance calculation methodology considering different particulate sizes is presented. A Gaussian-type dispersion model for PM that handles size particles larger than 0.1 {mu}m is used. The model considers primary particles and continuous emissions. PM concentration distribution at every affected geographical point defined by a grid is computed. Stochastic uncertainty caused by the natural variability of atmospheric parameters is taken into consideration in the dispersion model by applying a Monte Carlo methodology. The prototype package (STRRAP) that takes into account the stochastic behaviour of atmospheric variables, developed for risk assessment and safe distances calculation [Godoy SM, Santa Cruz ASM, Scenna NJ. STRRAP SYSTEM - A software for hazardous materials risk assessment and safe distances calculation. Reliability Engineering and System Safety 2007;92(7):847-57] is enlarged for the analysis of the PM air dispersion. STRRAP computes distances from the source to every affected receptor in each trial and generates the impact distance distribution for each particulate size. In addition, a representative impact distance value to delimit the affected area can be obtained. Fuel oil stack effluents dispersion in Rosario city is simulated as a case study. Mass concentration distributions and impact distances are computed for the range of interest in environmental air quality evaluations (PM{sub 2.5}-PM{sub 10})

Assessment of impact distances for particulate matter dispersion: A stochastic approach

International Nuclear Information System (INIS)

Godoy, S.M.; Mores, P.L.; Santa Cruz, A.S.M.; Scenna, N.J.

2009-01-01

It is known that pollutants can be dispersed from the emission sources by the wind, or settled on the ground. Particle size, stack height, topography and meteorological conditions strongly affect particulate matter (PM) dispersion. In this work, an impact distance calculation methodology considering different particulate sizes is presented. A Gaussian-type dispersion model for PM that handles size particles larger than 0.1 μm is used. The model considers primary particles and continuous emissions. PM concentration distribution at every affected geographical point defined by a grid is computed. Stochastic uncertainty caused by the natural variability of atmospheric parameters is taken into consideration in the dispersion model by applying a Monte Carlo methodology. The prototype package (STRRAP) that takes into account the stochastic behaviour of atmospheric variables, developed for risk assessment and safe distances calculation [Godoy SM, Santa Cruz ASM, Scenna NJ. STRRAP SYSTEM - A software for hazardous materials risk assessment and safe distances calculation. Reliability Engineering and System Safety 2007;92(7):847-57] is enlarged for the analysis of the PM air dispersion. STRRAP computes distances from the source to every affected receptor in each trial and generates the impact distance distribution for each particulate size. In addition, a representative impact distance value to delimit the affected area can be obtained. Fuel oil stack effluents dispersion in Rosario city is simulated as a case study. Mass concentration distributions and impact distances are computed for the range of interest in environmental air quality evaluations (PM 2.5 -PM 10 ).

A credit line appropriated for energy efficiency and renewable energy sources in Bulgaria

International Nuclear Information System (INIS)

Iliev, I.

2008-01-01

The credit line was developed by the European Bank for Reconstruction and Development (EBRD) in co-operation with the Bulgarian government. In this financial project several bulgarian banks are involved. The purpose of this project is to support mainly the private enterprises in the sector of energy efficiency and renewable energy sources. The main steps of the applying process are discussed and useful practical information is given. In Bulgaria till now 125 projects are successful financed with total amount about 72 million Euro. The projects will generate annually more than 457 000 MWh electric power and 615 285 MWh thermal power, as well as an annual reduction of about 494 200 t CO 2 emissions is expected

Characterisation of Aerosols from Simulated Radiological Dispersion Events

NARCIS (Netherlands)

Di Lemma, F.G.

2015-01-01

The research described in this thesis aims at improving the evaluation of the radiaoctive aerosol release from different Radiological Dispersion Events (RDE's), such as accidents and sabotage involving radioactive and nuclear materials. These studies help in a better assessment of the source term as

On-line micro-volume introduction system developed for lower density than water extraction solvent and dispersive liquid–liquid microextraction coupled with flame atomic absorption spectrometry

International Nuclear Information System (INIS)

Anthemidis, Aristidis N.; Mitani, Constantina; Balkatzopoulou, Paschalia; Tzanavaras, Paraskevas D.

2012-01-01

Highlights: ► A dispersive liquid–liquid micro extraction method for lead and copper determination. ► A micro-volume transportation system for extractant solvent lighter than water. ► Analysis of natural water samples. - Abstract: A simple and fast preconcentration/separation dispersive liquid–liquid micro extraction (DLLME) method for metal determination based on the use of extraction solvent with lower density than water has been developed. For this purpose a novel micro-volume introduction system was developed enabling the on-line injection of the organic solvent into flame atomic absorption spectrometry (FAAS). The effectiveness and efficiency of the proposed system were demonstrated for lead and copper preconcentration in environmental water samples using di-isobutyl ketone (DBIK) as extraction solvent. Under the optimum conditions the enhancement factor for lead and copper was 187 and 310 respectively. For a sample volume of 10 mL, the detection limit (3 s) and the relative standard deviation were 1.2 μg L −1 and 3.3% for lead and 0.12 μg L −1 and 2.9% for copper respectively. The developed method was evaluated by analyzing certified reference material and it was applied successfully to the analysis of environmental water samples.

Optical Variability of Narrow-line and Broad-line Seyfert 1 Galaxies

Energy Technology Data Exchange (ETDEWEB)

Rakshit, Suvendu; Stalin, C. S., E-mail: suvenduat@gmail.com [Indian Institute of Astrophysics, Block II, Koramangala, Bangalore-560034 (India)

2017-06-20

We studied the optical variability (OV) of a large sample of narrow-line Seyfert 1 (NLSy1) and broad-line Seyfert 1 (BLSy1) galaxies with z < 0.8 to investigate any differences in their OV properties. Using archival optical V -band light curves from the Catalina Real Time Transient Survey that span 5–9 years and modeling them using damped random walk, we estimated the amplitude of variability. We found that NLSy1 galaxies as a class show lower amplitude of variability than their broad-line counterparts. In the sample of both NLSy1 and BLSy1 galaxies, radio-loud sources are found to have higher variability amplitude than radio-quiet sources. Considering only sources that are detected in the X-ray band, NLSy1 galaxies are less optically variable than BLSy1 galaxies. The amplitude of variability in the sample of both NLSy1 and BLSy1 galaxies is found to be anti-correlated with Fe ii strength but correlated with the width of the H β line. The well-known anti-correlation of variability–luminosity and the variability–Eddington ratio is present in our data. Among the radio-loud sample, variability amplitude is found to be correlated with radio-loudness and radio-power, suggesting that jets also play an important role in the OV in radio-loud objects, in addition to the Eddington ratio, which is the main driving factor of OV in radio-quiet sources.

2.3. Global-scale atmospheric dispersion of microorganisms

Science.gov (United States)

Griffin, Dale W.; Gonzalez-Martin, Cristina; Hoose, C.; Smith, D.J.; Delort, Anne-Marie; Amato, Pierre

2018-01-01

This chapter addresses long-range dispersion and the survival of microorganisms across a wide range of altitudes in Earth's atmosphere. Topics include mechanisms of dispersion, survivability of microorganisms known to be associated with long-range transport, natural and artificial sources of bioaerosols, residence time estimation through the use of proxy aerosols, transport and emission models, and monitoring assays (both culture and molecular based). We conclude with a discussion of the known limits for Earth's biosphere boundary, relating aerobiology studies to planetary exploration given the large degree of overlapping requirements for in situ studies (including low biomass life detection and contamination control).

The Lagrangian particle dispersion model FLEXPART-WRF VERSION 3.1

Energy Technology Data Exchange (ETDEWEB)

Brioude, J.; Arnold, D.; Stohl, A.; Cassiani, M.; Morton, Don; Seibert, P.; Angevine, W. M.; Evan, S.; Dingwell, A.; Fast, Jerome D.; Easter, Richard C.; Pisso, I.; Bukhart, J.; Wotawa, G.

2013-11-01

The Lagrangian particle dispersion model FLEXPART was originally designed for cal- culating long-range and mesoscale dispersion of air pollutants from point sources, such as after an accident in a nuclear power plant. In the meantime FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. This multiscale need from the modeler community has encouraged new developments in FLEXPART. In this document, we present a version that works with the Weather Research and Forecasting (WRF) mesoscale meteoro- logical model. Simple procedures on how to run FLEXPART-WRF are presented along with special options and features that differ from its predecessor versions. In addition, test case data, the source code and visualization tools are provided to the reader as supplementary material.

Special transfer lines for the spallation neutron source

International Nuclear Information System (INIS)

Lucas, A.T.; Schippl, K.

1986-01-01

Special transfer lines were required to transport supercritical hydrogen gas at 20 0 K and 1.5 MPa and liquid methane at 800 0 K and 0.4 MPa over a distance of about 18 m, to moderator vessels sited within a concrete shielded area. The moderator vessels (1 L and 1/2 L volume respectively) are built into shielding material surrounding the uranium target which produces high energy pulsed neutrons. Energies up to 400 W can be deposited in the cryogenic fluid, which the control system must be capable of handling within less than one minute. The flow rates were designed to be 500 cm 3 /sec for hydrogen and 220 cms 3 /sec for methane. In order to maintain biological shielding integrity the lines had to be as compact in cross section as possible, and replacable using remote handling techniques. As commonly used plastic materials could not be used for spacers etc, on account of their poor radiation resistance, new techniques had to be developed to meet the long term requirements of the lines

In-town dispersion calculations with RIMPUFF and UDM

International Nuclear Information System (INIS)

Astrup, P.; Thykier-Nielsen, S.; Mikkelsen, Torben

2005-11-01

Input to ERMIN, deposition of radioactive matter inside inhabited areas from releases both within and outside such areas, shall in a decision support system be produced by dispersion codes, followed by data-assimilation. The present work focuses on the differences in near surface concentrations and in depositions obtained with a code designed for dispersion of a release from a nuclear power plant, typically situated at a distance from densely inhabited areas, and a code specifically designed for predicting dispersion from sources inside urban areas. The codes applied are the RIMPUFF code, RIsoe Mesoscale PUFF model from Risoe National Laboratory, Denmark, and the UDM code, Urban Dispersion Model, from 'dstl', Defence Science and Technology Laboratory, Porton Down, United Kingdom. For an above-town release only small differences are seen between the codes, but for a in-town ground release, e.g. a dirty bomb, the UDM code predicts much larger concentrations in an area close to the release point and, if wind shifts occur, gives a rather different plume all over. (au)

Correction of vertical crossing induced dispersion in LHC

International Nuclear Information System (INIS)

Meot, F.

1997-11-01

Beam crossing schemes in the LHC interaction regions impose non-zero vertical closed orbit in the low-β triplets, which excite a perturbative periodic dispersion; the phenomenon is described and quantified in detail. It is shown that this dispersion reaches values at the limit of tolerances in the nominal optics of Version 5.0 of the LHC ring, and prohibitively large values in particular in the low- β quadrupoles and interaction regions in the foreseen extreme β-squeeze case (β * = 0.25 m). Such behaviour justifies including a local correction in the LHC design, in order to damp the effect and confine it as much as possible in the vicinity of the excitation sources (the low-β triplets). An optical compensation scheme based on the use of skew quadrupoles is described in detail, as well as the entailed residual dispersion

Correction of vertical crossing induced dispersion in LHC

International Nuclear Information System (INIS)

Meot, F.

1997-11-01

Beam crossing schemes in the LHC interaction regions impose non-zero vertical closed orbit in the low-β triplets, which excite a perturbative periodic dispersion; the phenomenon is described and quantified in detail. It is shown that this dispersion reaches values at the limit of tolerances in the nominal optics of Version 5.0 of the LHC ring, and prohibitively large values in particular in the low-β quadrupoles and interaction regions in the foreseen extreme β-squeeze case (β * = 0.25 m). Such behavior justifies including a local correction in the LHC design, in order to damp the effect and confine it has such as possible in the vicinity of the excitation sources (the low-β triplets). An optical compensation scheme based on the use of skew quadrupoles is described in detail, as well as entailed residual dispersion. (author)

Emission quantification using the tracer gas dispersion method: The influence of instrument, tracer gas species and source simulation

DEFF Research Database (Denmark)

Delre, Antonio; Mønster, Jacob; Samuelsson, Jerker

2018-01-01

The tracer gas dispersion method (TDM) is a remote sensing method used for quantifying fugitive emissions by relying on the controlled release of a tracer gas at the source, combined with concentration measurements of the tracer and target gas plumes. The TDM was tested at a wastewater treatment...... plant for plant-integrated methane emission quantification, using four analytical instruments simultaneously and four different tracer gases. Measurements performed using a combination of an analytical instrument and a tracer gas, with a high ratio between the tracer gas release rate and instrument...... precision (a high release-precision ratio), resulted in well-defined plumes with a high signal-to-noise ratio and a high methane-to-tracer gas correlation factor. Measured methane emission rates differed by up to 18% from the mean value when measurements were performed using seven different instrument...

Synchrotron X-Ray Microdiffraction Studies of Electromigration in Interconnect lines at the Advanced Light Source

International Nuclear Information System (INIS)

Tamura, Nobumichi; Chen, Kai; Kunz, Martin

2009-01-01

Synchrotron polychromatic X-ray microdiffraction is a particularly suitable technique to study in situ the effect of electromigration in metal interconnects as add spatial resolution to grain orientation and strain sensitivity. This technique has been extensively used at the Advanced Light Source to monitor changes in aluminum and copper interconnect test structures while high-density current is passed into them during accelerated tests at elevated temperature. One of the principal findings is the observation of electromigration-induced plasticity in the metal lines that appear during the very early stages of electromigration. In some of the lines, high density of geometrically necessary dislocation are formed leading to additional diffusion paths causing an enhancement of electromigration effect at test temperature. This paper presents an overview of the principal results obtained from X-ray microdiffraction studies of electromigration effects on aluminum and copper interconnects at the ALS throughout continuous efforts that spanned over a decade (1998-2008) from approximately 40 weeks of combined beamtime.

Synchrotron X-Ray Microdiffraction Studies of Electromigration in Interconnect lines at the Advanced Light Source

Energy Technology Data Exchange (ETDEWEB)

Tamura, Nobumichi; Chen, Kai; Kunz, Martin

2009-05-01

Synchrotron polychromatic X-ray microdiffraction is a particularly suitable technique to study in situ the effect of electromigration in metal interconnects as add spatial resolution to grain orientation and strain sensitivity. This technique has been extensively used at the Advanced Light Source to monitor changes in aluminum and copper interconnect test structures while high-density current is passed into them during accelerated tests at elevated temperature. One of the principal findings is the observation of electromigration-induced plasticity in the metal lines that appear during the very early stages of electromigration. In some of the lines, high density of geometrically necessary dislocation are formed leading to additional diffusion paths causing an enhancement of electromigration effect at test temperature. This paper presents an overview of the principal results obtained from X-ray microdiffraction studies of electromigration effects on aluminum and copper interconnects at the ALS throughout continuous efforts that spanned over a decade (1998-2008) from approximately 40 weeks of combined beamtime.

[Disperse endocrine system and APUD concept].

Science.gov (United States)

Mil'to, I V; Sukhodolo, I V; Gereng, E A; Shamardina, L A

2011-01-01

This review describes the problems of disperse endocrine system and APUD-system morphology, summarizes some debatable issues of single endocrine cell biology. The data presented refer to the history of both systems discovery, morphological methods of their study, developmental sources, their structural organization and physiological roles of their cells. The significance of single endocrine cells in the regulation of the organism functions is discussed.

Identification of acoustic wave propagation in a duct line and its application to detection of impact source location based on signal processing

International Nuclear Information System (INIS)

Shin, Yong Woo; Kim, Min Soo; Lee, Sang Kwon

2010-01-01

For the detection of the impact location in a pipeline system, the correlation method has been the conventional method. For the application of the correlation method, the diameter of a duct should be small so that the acoustic wave inside the duct can propagate with nondispersive characteristics, in the form of, for example, a plane wave. This correlation method calculates the cross-correlation between acoustic waves measured at two acceleration sensors attached to a buried duct. It also gives information about the arrival time delay of an acoustic wave between two sensors. These arrival time delays are used for the estimation of the impact location. However, when the diameter of the duct is large, the acoustic waves inside the duct propagate with dispersive characteristics owing to the reflection of the acoustic wave off of the wall of the duct. This dispersive characteristic is related to the acoustic modes inside a duct. Therefore, the correlation method does not work correctly for the detection of the impact location. This paper proposes new methods of accurately measuring the arrival time delay between two sensors attached to duct line system. This method is based on the time-frequency analyses of the short time Fourier transform (STFT) and continuous wavelet transform (CWT). These methods can discriminate direct waves (non-dispersive waves) and reflective waves (dispersive waves) from the measured wave signals through the time-frequency analysis. The direct wave or the reflective wave is used to estimate the arrival time delay. This delay is used for the identification of the impact location. This systematic method can predict the impact location due to the impact forces of construction equipment with more accuracy than the correlation method

High-radiance LDP source for mask inspection and beam line applications (Conference Presentation)

Science.gov (United States)

Teramoto, Yusuke; Santos, Bárbara; Mertens, Guido; Kops, Ralf; Kops, Margarete; von Wezyk, Alexander; Bergmann, Klaus; Yabuta, Hironobu; Nagano, Akihisa; Ashizawa, Noritaka; Taniguchi, Yuta; Yamatani, Daiki; Shirai, Takahiro; Kasama, Kunihiko

2017-04-01

High-throughput actinic mask inspection tools are needed as EUVL begins to enter into volume production phase. One of the key technologies to realize such inspection tools is a high-radiance EUV source of which radiance is supposed to be as high as 100 W/mm2/sr. Ushio is developing laser-assisted discharge-produced plasma (LDP) sources. Ushio's LDP source is able to provide sufficient radiance as well as cleanliness, stability and reliability. Radiance behind the debris mitigation system was confirmed to be 120 W/mm2/sr at 9 kHz and peak radiance at the plasma was increased to over 200 W/mm2/sr in the recent development which supports high-throughput, high-precision mask inspection in the current and future technology nodes. One of the unique features of Ushio's LDP source is cleanliness. Cleanliness evaluation using both grazing-incidence Ru mirrors and normal-incidence Mo/Si mirrors showed no considerable damage to the mirrors other than smooth sputtering of the surface at the pace of a few nm per Gpulse. In order to prove the system reliability, several long-term tests were performed. Data recorded during the tests was analyzed to assess two-dimensional radiance stability. In addition, several operating parameters were monitored to figure out which contributes to the radiance stability. The latest model that features a large opening angle was recently developed so that the tool can utilize a large number of debris-free photons behind the debris shield. The model was designed both for beam line application and high-throughput mask inspection application. At the time of publication, the first product is supposed to be in use at the customer site.

A laboratory dispersant effectiveness test which reflects dispersant efficiency in the field

International Nuclear Information System (INIS)

Lunel, T.; Wood, P.

1996-01-01

Oil dispersion efficiencies of surfactants, from laboratory dispersion tests and field data were compared and calibrated. Data from an oil spill, where dispersants were used as a major part of the response, was analysed. The data was accumulated through the monitoring of the dispersant operation of the Sea Empress spill incident, in which Forties Blend oil was spilled at sea. This detailed data set was used to calibrate existing laboratory dispersant tests, and to devise a new International Dispersant Effectiveness Test. The objective was to create a comprehensive guide to decision making on whether and when to start a dispersant spraying operation. The dispersion efficiencies obtained from the laboratory dispersant tests were compared with field data. Flume tests produced the highest percentage of dispersed oil for all the dispersal tests. However, it was emphasised that the total percentage of oil dispersed should not be the only measure of dispersant effectiveness, since it does not distinguish between the contribution of natural and chemically enhanced dispersion. 9 refs., 1 tab., 9 figs

Solute transport along a single fracture in a porous rock: a simple analytical solution and its extension for modeling velocity dispersion

Science.gov (United States)

Liu, Longcheng; Neretnieks, Ivars; Shahkarami, Pirouz; Meng, Shuo; Moreno, Luis

2018-02-01

A simple and robust solution is developed for the problem of solute transport along a single fracture in a porous rock. The solution is referred to as the solution to the single-flow-path model and takes the form of a convolution of two functions. The first function is the probability density function of residence-time distribution of a conservative solute in the fracture-only system as if the rock matrix is impermeable. The second function is the response of the fracture-matrix system to the input source when Fickian-type dispersion is completely neglected; thus, the effects of Fickian-type dispersion and matrix diffusion have been decoupled. It is also found that the solution can be understood in a way in line with the concept of velocity dispersion in fractured rocks. The solution is therefore extended into more general cases to also account for velocity variation between the channels. This leads to a development of the multi-channel model followed by detailed statistical descriptions of channel properties and sensitivity analysis of the model upon changes in the model key parameters. The simulation results obtained by the multi-channel model in this study fairly well agree with what is often observed in field experiments—i.e. the unchanged Peclet number with distance, which cannot be predicted by the classical advection-dispersion equation. In light of the findings from the aforementioned analysis, it is suggested that forced-gradient experiments can result in considerably different estimates of dispersivity compared to what can be found in natural-gradient systems for typical channel widths.

Attenuation and velocity dispersion in the exploration seismic frequency band

Science.gov (United States)

Sun, Langqiu

In an anelastic medium, seismic waves are distorted by attenuation and velocity dispersion, which depend on petrophysical properties of reservoir rocks. The effective attenuation and velocity dispersion is a combination of intrinsic attenuation and apparent attenuation due to scattering, transmission response, and data acquisition system. Velocity dispersion is usually neglected in seismic data processing partly because of insufficient observations in the exploration seismic frequency band. This thesis investigates the methods of measuring velocity dispersion in the exploration seismic frequency band and interprets the velocity dispersion data in terms of petrophysical properties. Broadband, uncorrelated vibrator data are suitable for measuring velocity dispersion in the exploration seismic frequency band, and a broad bandwidth optimizes the observability of velocity dispersion. Four methods of measuring velocity dispersion in uncorrelated vibrator VSP data are investigated, which are the sliding window crosscorrelation (SWCC) method, the instantaneous phase method, the spectral decomposition method, and the cross spectrum method. Among them, the SWCC method is a new method and has satisfactory robustness, accuracy, and efficiency. Using the SWCC method, velocity dispersion is measured in the uncorrelated vibrator VSP data from three areas with different geological settings, i.e., Mallik gas hydrate zone, McArthur River uranium mines, and Outokumpu crystalline rocks. The observed velocity dispersion is fitted to a straight line with respect to log frequency for a constant (frequency-independent) Q value. This provides an alternative method for calculating Q. A constant Q value does not directly link to petrophysical properties. A modeling study is implemented for the Mallik and McArthur River data to interpret the velocity dispersion observations in terms of petrophysical properties. The detailed multi-parameter petrophysical reservoir models are built according to

Calculation of gamma ray dose buildup factors in water for isotropic point, plane mono directional and line sources using MCNP code

International Nuclear Information System (INIS)

Atak, H.; Celikten, O. S.; Tombakoglu, M.

2009-01-01

Gamma ray dose buildup factors in water for isotropic point, plane mono directional and infinite/finite line sources were calculated using the MCNP code. The buildup factors are determined for gamma ray energies of 1, 2, 3 and 4 Mev and for shield thicknesses of 1, 2, 4 and 7 mean free paths. The calculated buildup factors were then fitted in the Taylor and Berger forms. For the line sources a buildup factor table was also constructed using the Sievert function and the constants in Taylor form derived in this study to compare with the Monte Carlo results. All buildup factors were compared with the tabulated data given in literature. In order to reduce the statistical errors on buildup factors, 'forced collision' option was used in the MCNP calculations.

Adsorption of dispersing polyelectrolytes: stabilization of drilling fluids; Adsorption de polyelectrolytes dispersants: stabilisation des fluides de forage

Energy Technology Data Exchange (ETDEWEB)

Balastre, M.

1999-11-10

Instabilities of concentrated colloidal suspensions are a source of many industrial problems, as in drilling fluid formulations where aggregation and severe settling phenomena can occur. Low molecular weight polyelectrolyte dispersants are used to solve these problems, but their optimal use requires a better understanding of the phenomena that are involved. After materials characterization, adsorption mechanisms of two anionic polyelectrolytes (PANa, PSSNa) on a soluble substrate model, barium sulfate powder are studied. Barium sulfate is the principal additive used to adapt the density of drilling fluids. A simple model allows us to propose a distribution of the microscopic species at the interface. Presence of divalent ions induces the formation of a strong complex with the polyelectrolyte. Adsorption and electro-kinetic data are presented and exchange equilibrium are examined in relation with the surface uptake. The binding mechanism and the surface speciation of the polymer groups are deduced from the ion exchange analysis. The macroscopic behavior of suspensions on different conditions (volume fraction, ionic strength, dispersant concentration) is studied by settling and rheological measurements. The macroscopic properties are connected to structural aspects, and we show that dispersing effects are mostly related to electro-steric repulsion. The dispersion state depends on two principal factors adsorbed amounts and adsorbed layer properties, especially the excess charge, and the molecules conformation. (author)

Light absorption in thin quantizing semiconductor wires with non-parabolic law of dispersion of charge carriers

International Nuclear Information System (INIS)

Djotian, A.P.; Kazarian, E.M.; Karakashinian, Y.V.

1993-01-01

Interband absorption of light in a quantizing wire with non-parabolic dispersion law of charge carries, as well as energy spectrum and state densities are studied. The effect of Coulomb interaction between particles on the spectral curve of interband absorption is considered. Non-parabolic dispersion law of charge carries leads to an essential displacement of absorption line to ground state of one-dimensional exciton. 7 refs

Phonon dispersion relation in zircon, ZrSiO4 using inelastic neutron scattering at a pulsed neutron source

International Nuclear Information System (INIS)

Mittal, R.; Chaplot, S.L.; Parthasarathy, R.; Bull, M.J.; Harris, M.J.

2000-01-01

The coherent inelastic neutron scattering technique is used for the measurements of phonon dispersion relation in a geophysically important mineral zircon using PRISMA spectrometer as ISIS, UK. Lattice dynamical calculations of the phonon dispersion relation are carried out using a shell model. The one-phonon structure factors are calculated for selecting the Bragg points for the measurements and assignment of phonons to different branches. The calculations are in good agreement with the measured phonon dispersion relation. (author)

Human-mediated dispersal of aquatic invertebrates with waterproof footwear.

Science.gov (United States)

Valls, Luis; Castillo-Escrivà, Andreu; Mesquita-Joanes, Francesc; Armengol, Xavier

2016-02-01

Human-mediated dispersal has rarely been considered in wetland conservation strategies at regional scales, yet high concern exists about this aspect for (inter-)national management considering invasive species in other aquatic systems. In this context, we aim at understanding the role of human-mediated dispersal by footwear in protected wetlands with high conservation value. Zooplankton and zoobenthos were sampled in 13 shallow lakes in central Spain and, at the same time, mud attached to waders was collected and later cultured in deionized water under laboratory conditions for 4 weeks. Two-hundred and four individuals belonging to 19 invertebrate taxa were recovered after hatching; Ostracoda (84 %), Cladocera (53 %), Copepoda (30 %), Anostraca (30 %), and Notostraca (7 %) were the most frequent groups among the hatched crustaceans. NMDS and PERMANOVA analyses showed significant differences between the dispersed (via footwear) and the source active metacommunity, suggesting different dispersal abilities among the species found. Human vectors facilitate dispersal among protected lakes, which could eventuality lead to biotic homogenization and faster spread of non-indigenous species. Preservation strategies and education campaigns associated to target humans in close contact with water bodies should be imperative in conservation management of protected lakes.

Characteristics of a four element gyromagnetic nonlinear transmission line array high power microwave source

Energy Technology Data Exchange (ETDEWEB)

Johnson, J. M., E-mail: jared.johnson@ttu.edu; Reale, D. V.; Garcia, R. S.; Cravey, W. H.; Neuber, A. A.; Dickens, J. C.; Mankowski, J. J. [Center for Pulsed Power and Power Electronics Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States); Krile, J. T. [Department of Electromagnetics and Sensor Systems, Naval Surface Warfare Center - Dahlgren Division, Dahlgren, Virginia 22448 (United States)

2016-05-15

In this paper, a solid-state four element array gyromagnetic nonlinear transmission line high power microwave system is presented as well as a detailed description of its subsystems and general output capabilities. This frequency agile S-band source is easily adjusted from 2-4 GHz by way of a DC driven biasing magnetic field and is capable of generating electric fields of 7.8 kV/m at 10 m correlating to 4.2 MW of RF power with pulse repetition frequencies up to 1 kHz. Beam steering of the array at angles of ±16.7° is also demonstrated, and the associated general radiation pattern is detailed.

Magnetic properties as tracers for source-to-sink dispersal of sediments: A case study in the Taiwan Strait

Science.gov (United States)

Horng, Chorng-Shern; Huh, Chih-An

2011-09-01

Different lithologies between Taiwan and southeastern China lead to diverse mineralogical composition for weathering products derived from the two shores of the Taiwan Strait. Pyrrhotite and magnetite are respectively the dominant magnetic minerals associated with fluvial sediments from western Taiwan and southeastern China. While magnetite commonly co-exists with pyrrhotite in sediments sourced from Taiwan, pyrrhotite has not been found in sediments sourced from mainland China. Associated with such a distinction are vast differences in magnetic properties, including magnetic susceptibility (χ), SIRM, HIRM and the S-ratio, which can be used to study the provenances of sediments in the Taiwan Strait and adjoining marginal seas. Based on any two of these parameters, the magnetic characteristics of much of the Taiwan Strait sediment can be explained using a two-endmember mixing model. Source-to-sink dispersal of sediments in the Taiwan Strait can then be traced from the distribution of these parameters. The results not only corroborate an earlier study based on radionuclides and particle size distribution ( Huh et al., 2011) but reveal more diagnostic details. Besides spatial distribution based on a large number (216) of surface sediments, we also analyzed temporal variation of magnetic properties in six well-dated cores collected at key sites along the sediment source-to-sink pathways. From profiles of these parameters in cores from the middle of the northern Taiwan Strait, it is calculated that sediment supply from Taiwan has increased substantially in the past five decades, which may very well be related to accelerated land use and increased frequency of intense rainfalls in Taiwan during the same period. The approach described in this work may be extended to other source-to-sink systems around the world and through time, especially the mountainous islands fringing the Pacific and Indian Oceans in southeastern Asia. As with Taiwan, these islands have high

ALARA Review of the Spallation Neutron Source Accumulator Ring and Transfer Lines

Energy Technology Data Exchange (ETDEWEB)

Haire, M.J.

2003-06-30

The Spallation Neutron Source (SNS) is designed to meet the growing need for new tools that will deepen our understanding in materials science, life science, chemistry, fundamental and nuclear physics, earth and environmental sciences, and engineering sciences. The SNS is an accelerator-based neutron-scattering facility that when operational will produce an average beam power of 2 MW at a repetition rate of 60 Hz. The accelerator complex consists of the front-end systems, which will include an ion source; a 1-GeV full-energy linear accelerator; a single accumulator ring and its transfer lines; and a liquid mercury target. This report documents an as-low-as-reasonably-achievable (ALARA) review of the accumulator ring and transfer lines at their early design stage. An ALARA working group was formed and conducted a review of the SNS ring and transfer lines at the {approx}25% complete design stage to help ensure that ALARA principles are being incorporated into the design. The radiological aspects of the SNS design criteria were reviewed against regulatory requirements and ALARA principles. Proposed features and measures were then reviewed against the SNS design criteria. As part of the overall review, the working group reviewed the design manual; design drawings and process and instrumentation diagrams; the environment, safety, and health manual; and other related reports and literature. The group also talked with SNS design engineers to obtain explanations of pertinent subject matter. The ALARA group found that ALARA principles are indeed being incorporated into the early design stage. Radiation fields have been characterized, and shielding calculations have been performed. Radiological issues are being adequately addressed with regard to equipment selection, access control, confinement structure and ventilation, and contamination control. Radiation monitoring instrumentation for worker and environment protection are also being considered--a good practice at this

On the K-term and dispersion ratios of semi-regular variables

International Nuclear Information System (INIS)

Aslan, Z.

1981-01-01

Optical velocities of semi-regular (SR) and irregular (Lb) variables are analysed for a K-term. There is evidence for a dependence upon stellar period. Absorption lines in shorter period non-emission SR variables are blue-shifted relative to the centre-of-mass velocity by about 6 +- 3 km s -1 . Emission-line SR variables give a non-negative absorption K-term and Lb variables give no K-terms other than zero. Comparison is made with the K-terms implied by the OH velocity pattern in long-period variables. Dispersion ratios are also calculated. (author)

Amphiphilic Fluorinated Block Copolymer Synthesized by RAFT Polymerization for Graphene Dispersions

Directory of Open Access Journals (Sweden)

Hyang Moo Lee

2016-03-01

Full Text Available Despite the superior properties of graphene, the strong π–π interactions among pristine graphenes yielding massive aggregation impede industrial applications. For non-covalent functionalization of highly-ordered pyrolytic graphite (HOPG, poly(2,2,2-trifluoroethyl methacrylate-block-poly(4-vinyl pyridine (PTFEMA-b-PVP block copolymers were prepared by reversible addition-fragmentation chain transfer (RAFT polymerization and used as polymeric dispersants in liquid phase exfoliation assisted by ultrasonication. The HOPG graphene concentrations were found to be 0.260–0.385 mg/mL in methanolic graphene dispersions stabilized with 10 wt % (relative to HOPG PTFEMA-b-PVP block copolymers after one week. Raman and atomic force microscopy (AFM analyses revealed that HOPG could not be completely exfoliated during the sonication. However, on-line turbidity results confirmed that the dispersion stability of HOPG in the presence of the block copolymer lasted for one week and that longer PTFEMA and PVP blocks led to better graphene dispersibility. Force–distance (F–d analyses of AFM showed that PVP block is a good graphene-philic block while PTFEMA is methanol-philic.

Magneto-optical characterization of colloidal dispersions. Application to nickel nanoparticles.

Science.gov (United States)

Pascu, Oana; Caicedo, José Manuel; Fontcuberta, Josep; Herranz, Gervasi; Roig, Anna

2010-08-03

We report here on a fast magneto-optical characterization method for colloidal liquid dispersions of magnetic nanoparticles. We have applied our methodology to Ni nanoparticles with size equal or below 15 nm synthesized by a ligand stabilized solution-phase synthesis. We have measured the magnetic circular dichroism (MCD) of colloidal dispersions and found that we can probe the intrinsic magnetic properties within a wide concentration range, from 10(-5) up to 10(-2) M, with sensitivity to concentrations below 1 microg/mL of magnetic Ni particles. We found that the measured MCD signal scales up with the concentration thus providing a means of determining the concentration values of highly diluted dispersions. The methodology presented here exhibits large flexibility and versatility and might be suitable to study either fundamental problems related to properties of nanosize particles including surface related effects which are highly relevant for magnetic colloids in biomedical applications or to be applied to in situ testing and integration in production lines.

XMM-Newton Survey of Local O VII Absorption Lines in the Spectra of Galactic X-Ray Sources

Science.gov (United States)

Luo, Yang; Fang, Taotao; Ma, Renyi

2018-04-01

The detection of highly ionized metal absorption lines in the X-ray spectra of the Galactic X-ray binaries (XRBs) implies the distribution of hot gas along the sightline toward the background sources. However, the origin of this hot gas is still unclear: it can arise in the hot interstellar medium (ISM), or is intrinsic to the XRBs. In this paper, we present an XMM-Newton survey of the O VII absorption lines in the spectra of Galactic XRBs. A total of 33 XRBs were selected, with 29 low-mass XRBs and 4 high-mass XRBs. At a more than 3σ threshold, O VII absorption line was detected in 16 targets, among which 4 were newly discovered in this work. The average line equivalent width is centered around ∼20 mÅ. Additionally, we do not find strong correlations between the O VII EWs and the Galactic neutral absorption N H, the Galactic coordinates, or the distance of background targets. Such non-correlation may suggest contamination of the circumstellar material, or a lack of constraints on the line Doppler-b parameter. We also find that regardless of the direction of the XRBs, the O VII absorption lines are always detected when the flux of the background XRBs reaches a certain level, suggesting a uniform distribution of this hot gas. We estimate a ratio of 0.004–0.4 between the hot and neutral phases of the ISM. This is the second paper in the series following Fang et al. (2015), in which we focused on the local O VII absorption lines detected in the background AGN spectra. Detailed modeling of the hot ISM distribution will be investigated in a future paper.

Outflow Kinematics Manifested by the Hα Line: Gas Outflows in Type 2 AGNs. IV

Energy Technology Data Exchange (ETDEWEB)

Kang, Daeun; Woo, Jong-Hak; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

2017-08-20

Energetic ionized gas outflows driven by active galactic nuclei (AGNs) have been studied as a key phenomenon related to AGN feedback. To probe the kinematics of the gas in the narrow-line region, [O iii] λ 5007 has been utilized in a number of studies showing nonvirial kinematic properties due to AGN outflows. In this paper, we statistically investigate whether the H α emission line is influenced by AGN-driven outflows by measuring the kinematic properties based on the H α line profile and comparing them with those of [O iii]. Using the spatially integrated spectra of ∼37,000 Type 2 AGNs at z < 0.3 selected from the Sloan Digital Sky Survey DR7, we find a nonlinear correlation between H α velocity dispersion and stellar velocity dispersion that reveals the presence of the nongravitational component, especially for AGNs with a wing component in H α . The large H α velocity dispersion and velocity shift of luminous AGNs are clear evidence of AGN outflow impacts on hydrogen gas, while relatively smaller kinematic properties compared to those of [O iii] imply that the observed outflow effect on the H α line is weaker than the case of [O iii].

Optimization of wind speed on dispersion of pollutants using ...

Indian Academy of Sciences (India)

Department of Chemical Engineering, National Institute of Technology Calicut, ... The classical approaches of dispersion model (Qian & Venkatram 2001; ..... of ambient fine organic carbon particles and source apportionment of PM2.5 in Indian ... matrix factorization and chemical mass balance applied to receptor modeling.

Forest rodents provide directed dispersal of Jeffrey pine seeds

Science.gov (United States)

Briggs, J.S.; Wall, S.B.V.; Jenkins, S.H.

2009-01-01

Some species of animals provide directed dispersal of plant seeds by transporting them nonrandomly to microsites where their chances of producing healthy seedlings are enhanced. We investigated whether this mutualistic interaction occurs between granivorous rodents and Jeffrey pine (Pinus jeffreyi) in the eastern Sierra Nevada by comparing the effectiveness of random abiotic seed dispersal with the dispersal performed by four species of rodents: deer mice (Peromyscus maniculatus), yellow-pine and long-eared chipmunks (Tamias amoenus and T. quadrimaculatus), and golden-mantled ground squirrels (Spermophilus lateralis). We conducted two caching studies using radio-labeled seeds, the first with individual animals in field enclosures and the second with a community of rodents in open forest. We used artificial caches to compare the fates of seeds placed at the range of microsites and depths used by animals with the fates of seeds dispersed abiotically. Finally, we examined the distribution and survival of naturally establishing seedlings over an eight-year period.Several lines of evidence suggested that this community of rodents provided directed dispersal. Animals preferred to cache seeds in microsites that were favorable for emergence or survival of seedlings and avoided caching in microsites in which seedlings fared worst. Seeds buried at depths typical of animal caches (5–25 mm) produced at least five times more seedlings than did seeds on the forest floor. The four species of rodents differed in the quality of dispersal they provided. Small, shallow caches made by deer mice most resembled seeds dispersed by abiotic processes, whereas many of the large caches made by ground squirrels were buried too deeply for successful emergence of seedlings. Chipmunks made the greatest number of caches within the range of depths and microsites favorable for establishment of pine seedlings. Directed dispersal is an important element of the population dynamics of Jeffrey pine, a

Dexamethasone-Mediated Upregulation of Calreticulin Inhibits Primary Human Glioblastoma Dispersal Ex Vivo

Directory of Open Access Journals (Sweden)

Mohan Nair

2018-02-01

Full Text Available Dispersal of Glioblastoma (GBM renders localized therapy ineffective and is a major cause of recurrence. Previous studies have demonstrated that Dexamethasone (Dex, a drug currently used to treat brain tumor–related edema, can also significantly reduce dispersal of human primary GBM cells from neurospheres. It does so by triggering α5 integrin activity, leading to restoration of fibronectin matrix assembly (FNMA, increased neurosphere cohesion, and reduction of neurosphere dispersal velocity (DV. How Dex specifically activates α5 integrin in these GBM lines is unknown. Several chaperone proteins are known to activate integrins, including calreticulin (CALR. We explore the role of CALR as a potential mediator of Dex-dependent induction of α5 integrin activity in primary human GBM cells. We use CALR knock-down and knock-in strategies to explore the effects on FNMA, aggregate compaction, and dispersal velocity in vitro, as well as dispersal ex vivo on extirpated mouse retina and brain slices. We show that Dex increases CALR expression and that siRNA knockdown suppresses Dex-mediated FNMA. Overexpression of CALR in GBM cells activates FNMA, increases compaction, and decreases DV in vitro and on explants of mouse retina and brain slices. Our results define a novel interaction between Dex, CALR, and FNMA as inhibitors of GBM dispersal.

A numerical study of air pollutant dispersion with bimolecular chemical reactions in an urban street canyon using large-eddy simulation

Science.gov (United States)

Kikumoto, Hideki; Ooka, Ryozo

2012-07-01

A large-eddy simulation is performed on a turbulent dispersion of chemically reactive air pollutants in a two-dimensional urban street canyon with an aspect ratio of 1.0. Nitrogen monoxide emitted from a line-source set on the bottom of the street canyon disperses and reacts with Ozone included in a free stream. The reactions have significant influences on the concentrations of pollutants in the canyon space, and they increase the concentrations of the reaction products relative to of the concentrations of the reactants. The transport of air pollutants through a free shear layer above the canyon is closely related to the structure of the turbulence. Gases in the canyon are mainly exhausted when low-speed regions appear above the canyon. In contrast, pollutants in the free stream flow into the canyon with high-speed fluid bodies. Consequently, the correlation between the time fluctuations of the reactants' concentrations strongly affects the reaction rates in the region near the free shear layer. In this calculation, the correlation term reaches to a value of 20% of the mean reaction rate at a maximum there.

Update on pigment dispersion syndrome and pigmentary glaucoma.

Science.gov (United States)

Okafor, Kingsley; Vinod, Kateki; Gedde, Steven J

2017-03-01

The present article reviews the clinical features and pathogenesis of pigment dispersion syndrome and pigmentary glaucoma and provides an update regarding their diagnosis and management. Newer imaging modalities including ultrasound biomicroscopy and anterior segment optical coherence tomography facilitate visualization of the iris concavity characteristic of eyes with pigment dispersion syndrome and pigmentary glaucoma. Patients with pigmentary glaucoma may be distinguished from those with other glaucoma types by the presence of typical symptoms, personality type, and patterns of diurnal intraocular pressure fluctuation. Although laser iridotomy has been shown to alter iris anatomy in pigmentary glaucoma, it is not proven to slow visual field progression. Multiple trials have validated the safety and efficacy of filtering surgery in treating pigmentary glaucoma, with fewer studies published on the role of micro-invasive glaucoma surgery. Literature from the review period has further defined the unique clinical characteristics of pigment dispersion syndrome and pigmentary glaucoma. Laser surgery has a limited role in the management of these entities, whereas trabeculectomy remains an acceptable first-line surgical treatment. Further studies are needed to define the potential application of the newer micro-invasive glaucoma procedures in pigmentary glaucoma.

Raising the acceptance of the AP2-line

International Nuclear Information System (INIS)

Trbojevic, D.

1989-01-01

The 120 GeV Main Ring proton beam collides with the target at the end of the AP-1 line and creates antiprotons and other secondary particles. The AP-2 line transfers the negative particles from the target to the Debuncher. To provide a bigger antiproton stack size in the Accumulator, both the Debuncher as well as the AP-2 line acceptance have to be raised. This is a proposal for the improvement of the AP-2 line acceptance. The first part of the memo presents an acceptance examination of the existing AP-2 line by computer simulation, while the second presents a short proposal for aperture corrections. The computer program TURTLE was used to trace antiprotons through the AP-2 line without taking into account other negative charged particles. Betatron functions were obtained from the output of the SYNCH computer program. The SYNCH program was also used to check the dispersion match between the AP-2 line and the Debuncher. 3 refs., 6 figs., 5 tabs

Improved atmospheric dispersion modelling in the new program system UFOMOD for accident consequence assessments

International Nuclear Information System (INIS)

Panitz, H.J.

1988-01-01

An essential aim of the improvements of the new program system UFOMOD for Accident Consequence Assessments (ACAs) was to substitute the straightline Gaussian plume model conventionally used in ACA models by more realistic atmospheric dispersion models. To identify improved models which can be applied in ACA codes and to quantify the implications of different concepts of dispersion modelling on the results of an ACA, probabilistic comparative calculations with different atmospheric dispersion models have been carried out. The study showed that there are trajectory models available which can be applied in ACAs and that these trajectory models provide more realistic results of ACAs than straight-line Gaussian models. This led to a completly novel concept of atmospheric dispersion modelling which distinguish between two different distance ranges of validity: the near range ( 50 km). The two ranges are assigned to respective trajectory models

Approximate method for treating dispersion in one-way quantum channels

International Nuclear Information System (INIS)

Stace, T. M.; Wiseman, H. M.

2006-01-01

Coupling the output of a source quantum system into a target quantum system is easily treated by cascaded systems theory if the intervening quantum channel is dispersionless. However, dispersion may be important in some transfer protocols, especially in solid-state systems. In this paper we show how to generalize cascaded systems theory to treat such dispersion, provided it is not too strong. We show that the technique also works for fermionic systems with a low flux, and can be extended to treat fermionic systems with large flux. To test our theory, we calculate the effect of dispersion on the fidelity of a simple protocol of quantum state transfer. We find good agreement with an approximate analytical theory that had been previously developed for this example

Spatial dispersion effects in spectral line broadening by pressure. I. The Bouguer Law and absorption coefficient

International Nuclear Information System (INIS)

Cherkasov, M.R.

1995-01-01

Based on the general principles of semiclassical electrodynamics, the Bouguer law is derived, and the expression for the absorption coefficient is obtained, formally including all effects related to the phenomenon of spatial dispersion

Design of x-ray diagnostic beam line for a synchrotron radiation source and measurement results

Energy Technology Data Exchange (ETDEWEB)

Garg, Akash Deep, E-mail: akash-deep@rrcat.gov.in; Karnewar, A.K.; Ojha, A.; Shrivastava, B.B.; Holikatti, A.C.; Puntambekar, T.A.; Navathe, C.P.

2014-08-01

Indus-2 is a 2.5 GeV synchrotron radiation source (SRS) operational at the Raja Ramanna Centre for Advanced Technology (RRCAT) in India. We have designed, developed and commissioned x-ray diagnostic beam line (X-DBL) at the Indus-2. It is based on pinhole array imaging (8–18 keV). We have derived new equations for online measurements of source position and emission angle with pinhole array optics. Measured values are compared with the measurements at an independent x-ray beam position monitor (staggered pair blade monitor) installed in the X-DBL. The measured values are close to the theoretical expected values within ±12 µm (or ±1.5 μrad) for sufficiently wide range of the beam movements. So, beside the beam size and the beam emittance, online information for the vertical position and angle is also used in the orbit steering. In this paper, the various design considerations of the X-DBL and online measurement results are presented.

Osteocytes, not Osteoblasts or Lining Cells, are the Main Source of the RANKL Required for Osteoclast Formation in Remodeling Bone.

Directory of Open Access Journals (Sweden)

Jinhu Xiong

Full Text Available The cytokine receptor activator of nuclear factor kappa B ligand (RANKL, encoded by the Tnfsf11 gene, is essential for osteoclastogenesis and previous studies have shown that deletion of the Tnfsf11 gene using a Dmp1-Cre transgene reduces osteoclast formation in cancellous bone by more than 70%. However, the Dmp1-Cre transgene used in those studies leads to recombination in osteocytes, osteoblasts, and lining cells making it unclear whether one or more of these cell types produce the RANKL required for osteoclast formation in cancellous bone. Because osteoblasts, osteocytes, and lining cells have distinct locations and functions, distinguishing which of these cell types are sources of RANKL is essential for understanding the orchestration of bone remodeling. To distinguish between these possibilities, we have now created transgenic mice expressing the Cre recombinase under the control of regulatory elements of the Sost gene, which is expressed in osteocytes but not osteoblasts or lining cells in murine bone. Activity of the Sost-Cre transgene in osteocytes, but not osteoblast or lining cells, was confirmed by crossing Sost-Cre transgenic mice with tdTomato and R26R Cre-reporter mice, which express tdTomato fluorescent protein or LacZ, respectively, only in cells expressing the Cre recombinase or their descendants. Deletion of the Tnfsf11 gene in Sost-Cre mice led to a threefold decrease in osteoclast number in cancellous bone and increased cancellous bone mass, mimicking the skeletal phenotype of mice in which the Tnfsf11 gene was deleted using the Dmp1-Cre transgene. These results demonstrate that osteocytes, not osteoblasts or lining cells, are the main source of the RANKL required for osteoclast formation in remodeling cancellous bone.

Effects of Fetch on Turbulent Flow and Pollutant Dispersion Within a Cubical Canopy

Science.gov (United States)

Michioka, Takenobu; Takimoto, Hiroshi; Ono, Hiroki; Sato, Ayumu

2018-03-01

The effects of fetch on turbulent flow and pollutant dispersion within a canopy formed by regularly-spaced cubical objects is investigated using large-eddy simulation. Six tracer gases are simultaneously released from a ground-level continuous pollutant line source placed parallel to the spanwise axis at the first, second, third, fifth, seventh and tenth rows. Beyond the seventh row, the standard deviations of the fluctuations in the velocity components and the Reynolds shear stresses reach nearly equivalent states. Low-frequency turbulent flow is generated near the bottom surface around the first row and develops as the fetch increases. The turbulent flow eventually passes through the canopy at a near-constant interval. The mean concentration within the canopy reaches a near-constant value beyond the seventh row. In the first and second rows, narrow coherent structures frequently affect the pollutant escape from the top of the canopy. These structures increase in width as the fetch increases, and they mainly affect the removal of pollutants from the canopy.

Implementation of meso-scale radioactive dispersion model for GPU

Energy Technology Data Exchange (ETDEWEB)

Sunarko [National Nuclear Energy Agency of Indonesia (BATAN), Jakarta (Indonesia). Nuclear Energy Assessment Center; Suud, Zaki [Bandung Institute of Technology (ITB), Bandung (Indonesia). Physics Dept.

2017-05-15

Lagrangian Particle Dispersion Method (LPDM) is applied to model atmospheric dispersion of radioactive material in a meso-scale of a few tens of kilometers for site study purpose. Empirical relationships are used to determine the dispersion coefficient for various atmospheric stabilities. Diagnostic 3-D wind-field is solved based on data from one meteorological station using mass-conservation principle. Particles representing radioactive pollutant are dispersed in the wind-field as a point source. Time-integrated air concentration is calculated using kernel density estimator (KDE) in the lowest layer of the atmosphere. Parallel code is developed for GTX-660Ti GPU with a total of 1 344 scalar processors using CUDA. A test of 1-hour release discovers that linear speedup is achieved starting at 28 800 particles-per-hour (pph) up to about 20 x at 14 4000 pph. Another test simulating 6-hour release with 36 000 pph resulted in a speedup of about 60 x. Statistical analysis reveals that resulting grid doses are nearly identical in both CPU and GPU versions of the code.

Development of uniform hazard response spectra for rock sites considering line and point sources of earthquakes

International Nuclear Information System (INIS)

Ghosh, A.K.; Kushwaha, H.S.

2001-12-01

Traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration (PGA). The mean recurrence interval (MRI) used to computed for PGA only. It is shown that the MRI associated with such response spectra are not the same at all frequencies. The present work develops uniform hazard response spectra i.e. spectra having the same MRI at all frequencies for line and point sources of earthquakes by using a large number of strong motion accelerograms recorded on rock sites. Sensitivity of the number of the results to the changes in various parameters has also been presented. This work is an extension of an earlier work for aerial sources of earthquakes. These results will help to determine the seismic hazard at a given site and the associated uncertainities. (author)

First on-line results for As and F beams from HRIBF target/ion sources

International Nuclear Information System (INIS)

Carter, H.K.; Kormicki, J.; Stracener, D.W.; Breitenbach, J.B.; Blackmon, J.C.; Smith, M.S.; Bardayan, D.W.

1996-01-01

The first on-line tests of the ion sources to provide radioactive ion beams of 69,70 As and 17,18 F for the Holifield Radioactive Ion Beam Facility have been performed using the UNISOR facility at HRIBF. For 70 As the measured efficiency is 0.8 ± 0.3% with a hold-up time of 3.6 ± 0.3 hours as measured with 72 As at a target temperature of 1,270 C. For 17 F the efficiency for Al 17 F is 0.0024 ± 0.0008% with a hold-up time of 16.4 ± 0.8 m as measured with Al 18 F at a target temperature of 1,470 C

Dynamics and molecular determinants of cytoplasmic lipid droplet clustering and dispersion.

Directory of Open Access Journals (Sweden)

David J Orlicky

Full Text Available Perilipin-1 (Plin1, a prominent cytoplasmic lipid droplet (CLD binding phosphoprotein and key physiological regulator of triglyceride storage and lipolysis in adipocytes, is thought to regulate the fragmentation and dispersion of CLD that occurs in response to β-adrenergic activation of adenylate cyclase. Here we investigate the dynamics and molecular determinants of these processes using cell lines stably expressing recombinant forms of Plin1 and/or other members of the perilipin family. Plin1 and a C-terminal CLD-binding fragment of Plin1 (Plin1CT induced formation of single dense CLD clusters near the microtubule organizing center, whereas neither an N-terminal CLD-binding fragment of Plin1, nor Plin2 or Plin3 induced clustering. Clustered CLD coated by Plin1, or Plin1CT, dispersed in response to isoproterenol, or other agents that activate adenylate cyclase, in a process inhibited by the protein kinase A inhibitor, H89, and blocked by microtubule disruption. Isoproterenol-stimulated phosphorylation of CLD-associated Plin1 on serine 492 preceded their dispersion, and live cell imaging showed that cluster dispersion involved initial fragmentation of tight clusters into multiple smaller clusters, which then fragmented into well-dispersed individual CLD. siRNA knockdown of the cortical actin binding protein, moesin, induced disaggregation of tight clusters into multiple smaller clusters, and inhibited the reaggregation of dispersed CLD into tight clusters. Together these data suggest that the clustering and dispersion processes involve a complex orchestration of phosphorylation-dependent, microtubule-dependent and independent, and microfilament dependent steps.

Dynamics and molecular determinants of cytoplasmic lipid droplet clustering and dispersion.

Science.gov (United States)

Orlicky, David J; Monks, Jenifer; Stefanski, Adrianne L; McManaman, James L

2013-01-01

Perilipin-1 (Plin1), a prominent cytoplasmic lipid droplet (CLD) binding phosphoprotein and key physiological regulator of triglyceride storage and lipolysis in adipocytes, is thought to regulate the fragmentation and dispersion of CLD that occurs in response to β-adrenergic activation of adenylate cyclase. Here we investigate the dynamics and molecular determinants of these processes using cell lines stably expressing recombinant forms of Plin1 and/or other members of the perilipin family. Plin1 and a C-terminal CLD-binding fragment of Plin1 (Plin1CT) induced formation of single dense CLD clusters near the microtubule organizing center, whereas neither an N-terminal CLD-binding fragment of Plin1, nor Plin2 or Plin3 induced clustering. Clustered CLD coated by Plin1, or Plin1CT, dispersed in response to isoproterenol, or other agents that activate adenylate cyclase, in a process inhibited by the protein kinase A inhibitor, H89, and blocked by microtubule disruption. Isoproterenol-stimulated phosphorylation of CLD-associated Plin1 on serine 492 preceded their dispersion, and live cell imaging showed that cluster dispersion involved initial fragmentation of tight clusters into multiple smaller clusters, which then fragmented into well-dispersed individual CLD. siRNA knockdown of the cortical actin binding protein, moesin, induced disaggregation of tight clusters into multiple smaller clusters, and inhibited the reaggregation of dispersed CLD into tight clusters. Together these data suggest that the clustering and dispersion processes involve a complex orchestration of phosphorylation-dependent, microtubule-dependent and independent, and microfilament dependent steps.

Using line acceleration to measure false killer whale (Pseudorca crassidens) click and whistle source levels during pelagic longline depredation.

Science.gov (United States)

Thode, Aaron; Wild, Lauren; Straley, Janice; Barnes, Dustin; Bayless, Ali; O'Connell, Victoria; Oleson, Erin; Sarkar, Jit; Falvey, Dan; Behnken, Linda; Martin, Sean

2016-11-01

False killer whales (Pseudorca crassidens) depredate pelagic longlines in offshore Hawaiian waters. On January 28, 2015 a depredation event was recorded 14 m from an integrated GoPro camera, hydrophone, and accelerometer, revealing that false killer whales depredate bait and generate clicks and whistles under good visibility conditions. The act of plucking bait off a hook generated a distinctive 15 Hz line vibration. Two similar line vibrations detected at earlier times permitted the animal's range and thus signal source levels to be estimated over a 25-min window. Peak power spectral density source levels for whistles (4-8 kHz) were estimated to be between 115 and 130 dB re 1 μPa 2 /Hz @ 1 m. Echolocation click source levels over 17-32 kHz bandwidth reached 205 dB re 1 μPa @ 1 m pk-pk, or 190 dB re 1 μPa @ 1 m (root-mean-square). Predicted detection ranges of the most intense whistles are 10 to 25 km at respective sea states of 4 and 1, with click detection ranges being 5 times smaller than whistles. These detection range analyses provide insight into how passive acoustic monitoring might be used to both quantify and avoid depredation encounters.

Dispersion bias, dispersion effect, and the aerosol-cloud conundrum

International Nuclear Information System (INIS)

Liu Yangang; Daum, Peter H; Guo Huan; Peng Yiran

2008-01-01

This work examines the influences of relative dispersion (the ratio of the standard deviation to the mean radius of the cloud droplet size distribution) on cloud albedo and cloud radiative forcing, derives an analytical formulation that accounts explicitly for the contribution from droplet concentration and relative dispersion, and presents a new approach to parameterize relative dispersion in climate models. It is shown that inadequate representation of relative dispersion in climate models leads to an overestimation of cloud albedo, resulting in a negative bias of global mean shortwave cloud radiative forcing that can be comparable to the warming caused by doubling CO 2 in magnitude, and that this dispersion bias is likely near its maximum for ambient clouds. Relative dispersion is empirically expressed as a function of the quotient between cloud liquid water content and droplet concentration (i.e., water per droplet), yielding an analytical formulation for the first aerosol indirect effect. Further analysis of the new expression reveals that the dispersion effect not only offsets the cooling from the Twomey effect, but is also proportional to the Twomey effect in magnitude. These results suggest that unrealistic representation of relative dispersion in cloud parameterization in general, and evaluation of aerosol indirect effects in particular, is at least in part responsible for several outstanding puzzles of the aerosol-cloud conundrum: for example, overestimation of cloud radiative cooling by climate models compared to satellite observations; large uncertainty and discrepancy in estimates of the aerosol indirect effect; and the lack of interhemispheric difference in cloud albedo.

Experimental arrangement to measure dispersion in optical fiber devices

International Nuclear Information System (INIS)

Armas Rivera, Ivan; Beltran Perez, Georgina; Castillo Mixcoatl, Juan; Munoz Aguirre, Severino; Zaca Moran, Placido

2011-01-01

Dispersion is a quite important parameter in systems based on optical fiber, especially in pulsed emission lasers, where the temporal width is affected by such parameter. Therefore, it is necessary to consider the dispersion provoked by each component in the cavity. There are various experimental interferometric arrangements to evaluate this parameter. Generally, these systems modify the wavelength to obtain information about the n(λ) dependency, which is contained in the interferogram phase. However, this makes the system quite slow and it requires tunable and narrow bandwidth laser sources. In the present work, results obtained from an arrangement based on Mach-Zehnder interferometer where one of the arms is the optical fiber under study, while the reference one is air, are presented. In order to determine the n(λ) dependency, a wide spectrum light source was used in the wavelength range of interest. The phase information was evaluated from the interferometric signal measured by an optical spectrum analyzer.

Experimental arrangement to measure dispersion in optical fiber devices

Energy Technology Data Exchange (ETDEWEB)

Armas Rivera, Ivan [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias de la Electronica (Mexico); Beltran Perez, Georgina; Castillo Mixcoatl, Juan; Munoz Aguirre, Severino [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico Matematicas (Mexico); Zaca Moran, Placido, E-mail: ivan_rr1@hotmail.com [Benemerita Universidad Autonoma de Puebla, Fisicoquimica de Materiales ICUAP (Mexico)

2011-01-01

Dispersion is a quite important parameter in systems based on optical fiber, especially in pulsed emission lasers, where the temporal width is affected by such parameter. Therefore, it is necessary to consider the dispersion provoked by each component in the cavity. There are various experimental interferometric arrangements to evaluate this parameter. Generally, these systems modify the wavelength to obtain information about the n({lambda}) dependency, which is contained in the interferogram phase. However, this makes the system quite slow and it requires tunable and narrow bandwidth laser sources. In the present work, results obtained from an arrangement based on Mach-Zehnder interferometer where one of the arms is the optical fiber under study, while the reference one is air, are presented. In order to determine the n({lambda}) dependency, a wide spectrum light source was used in the wavelength range of interest. The phase information was evaluated from the interferometric signal measured by an optical spectrum analyzer.

Blueshifted [O I] lines from protoplanetary discs: the smoking gun of X-ray photoevaporation

Science.gov (United States)

Ercolano, Barbara; Owen, James E.

2016-08-01

Photoevaporation of protoplanetary discs by high-energy radiation from the central young stellar object is currently the favourite model to explain the sudden dispersal of discs from the inside out. While several theoretical works have provided a detailed pictured of this process, the direct observational validation is still lacking. Emission lines produced in these slow-moving protoplanetary disc winds may bear the imprint of the wind structure and thus provide a potential diagnostic of the underlying dispersal process. In this paper, we primarily focus on the collisionally excited neutral oxygen line at 6300 Å. We compare our models predictions to observational data and demonstrate a thermal origin for the observed blueshifted low-velocity component of this line from protoplanetary discs. Furthermore, our models show that while this line is a clear tell-tale sign of a warm, quasi-neutral disc wind, typical of X-ray photoevaporation, its strong temperature dependence makes it unsuitable to measure detailed wind quantities like mass-loss rate.

Surface-induced patterns from evaporating droplets of aqueous carbon nanotube dispersions

KAUST Repository

Zeng, Hongbo; Kristiansen, Kai De Lange; Wang, Peng; Bergli, Joakim; Israelachvili, Jacob N.

2011-01-01

Evaporation of aqueous droplets of carbon nanotubes (CNTs) coated with a physisorbed layer of humic acid (HA) on a partially hydrophilic substrate induces the formation of a film of CNTs. Here, we investigate the role that the global geometry of the substrate surfaces has on the structure of the CNT film. On a flat mica or silica surface, the evaporation of a convex droplet of the CNT dispersion induces the well-known "coffee ring", while evaporation of a concave droplet (capillary meniscus) of the CNT dispersion in a wedge of two planar mica sheets or between two crossed-cylinder sheets induces a large area (>mm 2) of textured or patterned films characterized by different short- and long-range orientational and positional ordering of the CNTs. The resulting patterns appear to be determined by two competing or cooperative sedimentation mechanisms: (1) capillary forces between CNTs giving micrometer-sized filaments parallel to the boundary line of the evaporating droplet and (2) fingering instability at the boundary line of the evaporating droplet and subsequent pinning of CNTs on the surface giving micrometer-sized filaments of CNTs perpendicular to this boundary line. The interplay between substrate surface geometry and sedimentation mechanisms gives an extra control parameter for manipulating patterns of self-assembling nanoparticles at substrate surfaces. © 2011 American Chemical Society.

Surface-induced patterns from evaporating droplets of aqueous carbon nanotube dispersions

KAUST Repository

Zeng, Hongbo

2011-06-07

Evaporation of aqueous droplets of carbon nanotubes (CNTs) coated with a physisorbed layer of humic acid (HA) on a partially hydrophilic substrate induces the formation of a film of CNTs. Here, we investigate the role that the global geometry of the substrate surfaces has on the structure of the CNT film. On a flat mica or silica surface, the evaporation of a convex droplet of the CNT dispersion induces the well-known "coffee ring", while evaporation of a concave droplet (capillary meniscus) of the CNT dispersion in a wedge of two planar mica sheets or between two crossed-cylinder sheets induces a large area (>mm 2) of textured or patterned films characterized by different short- and long-range orientational and positional ordering of the CNTs. The resulting patterns appear to be determined by two competing or cooperative sedimentation mechanisms: (1) capillary forces between CNTs giving micrometer-sized filaments parallel to the boundary line of the evaporating droplet and (2) fingering instability at the boundary line of the evaporating droplet and subsequent pinning of CNTs on the surface giving micrometer-sized filaments of CNTs perpendicular to this boundary line. The interplay between substrate surface geometry and sedimentation mechanisms gives an extra control parameter for manipulating patterns of self-assembling nanoparticles at substrate surfaces. © 2011 American Chemical Society.

Dispersion, sorption and photodegradation of petroleum hydrocarbons in dispersant-seawater-sediment systems.

Science.gov (United States)

Zhao, Xiao; Liu, Wen; Fu, Jie; Cai, Zhengqing; O'Reilly, S E; Zhao, Dongye

2016-08-15

This work examined effects of model oil dispersants on dispersion, sorption and photodegradation of petroleum hydrocarbons in simulated marine systems. Three dispersants (Corexit 9500A, Corexit 9527A and SPC 1000) were used to prepare dispersed water accommodated oil (DWAO). While higher doses of dispersants dispersed more n-alkanes and PAHs, Corexit 9500A preferentially dispersed C11-C20 n-alkanes, whereas Corexit 9527A was more favorable for smaller alkanes (C10-C16), and SPC 1000 for C12-C28 n-alkanes. Sorption of petroleum hydrocarbons on sediment was proportional to TPH types/fractions in the DWAOs. Addition of 18mg/L of Corexit 9500A increased sediment uptake of 2-3 ring PAHs, while higher dispersant doses reduced the uptake, due to micelle-enhanced solubilization effects. Both dispersed n-alkanes and PAHs were susceptible to photodegradation under simulated sunlight. For PAHs, both photodegradation and photo-facilitated alkylation were concurrently taking place. The information can facilitate sounder assessment of fate and distribution of dispersed oil hydrocarbons in marine systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Climate induced changes in the circulation and dispersal patterns of ...

Indian Academy of Sciences (India)

Climate induced changes in the circulation and dispersal patterns of the fluvial sources during late Quaternary in the middle Bengal Fan ... in 14C dated box cores from the eastern, the central and the western regions were studied to determine ...

Modelling surface radioactive spill dispersion in the Alborán Sea.

Science.gov (United States)

Periáñez, R

2006-01-01

The Strait of Gibraltar and the Alborán Sea are the only connection between the Atlantic Ocean and the Mediterranean Sea. Intense shipping activities occur in the area, including transport of waste radionuclides and transit of nuclear submarines. Thus, it is relevant to have a dispersion model that can be used in an emergency situation after an accident, to help the decision-making process. Such dispersion model requires an appropriate description of the physical oceanography of the region of interest, with simulations of tides and residual (average) circulation. In this work, a particle-tracking dispersion model that can be used to simulate the dispersion of radionuclides in the system Strait of Gibraltar-Alborán Sea is described. Tides are simulated using a barotropic model and for the average circulation a reduced-gravity model is applied. This model is able to reproduce the main features of the Alborán circulation (the well known Western Alborán Gyre, WAG, and the coastal circulation mode). The dispersion model is run off-line, using previously computed tidal and residual currents. The contamination patch is simulated by a number of particles whose individual paths are computed; diffusion and decay being modelled using a Monte Carlo method. Radionuclide concentrations may be obtained from the density of particles per water volume unit. Results from the hydrodynamic models have been compared with observations in the area. Several examples of dispersion computations under different wind and circulation conditions are presented.

Atmospheric dispersion models for real-time application in the decision support system being developed within the CEC

International Nuclear Information System (INIS)

Mikkelsen, T.

1992-01-01

A number of Commission of the European Communities member states are presently coordinating their research and development of a ''Real-time On-line DecisiOn Support'' (RODOS) for emergency assistance in the event of nuclear accident. In addition to atmospheric dispersion, the system involves multiple other radiological disciplines. The ability to estimate a specific atmospheric dispersion scenarios in real-time becomes a first-priority task and is of uttermost importance for the subsequent success or failure of such a comprehensive decision support system to guide off-site emergency situations. No single dispersion model is at present able to cover all possible release-types and scales of dispersion. A hierarchy of atmospheric flow and dispersion models is presently being ranked for suitability to real-time calculate air and integrated-air concentrations. Starting at the short-range scale, models are discriminated with respect to principle, adequacy and flexibility, CPU-time constraints, experimental evaluation record, instantaneous or short-time release handling, deposition measures (wet and dry), input and output data flexibility and uncertainty-handling and model-interpretation. Additional features of particular importance are: Robustness in schemes for meteorological preprocessing of meteorological input data, and on-line backfitting and data-assimilation procedures. Models demonstrating practical and operational use, including real-time operational experience, have in this context the highest priority, as opposed to the more sophisticated and theoretical ''development-type'' models. Real-time methods founded on our present knowledge and data concerning flow and dispersion in the atmospheric boundary layer, are of primary interest. (au) (18 refs.)

Line strengths in WN stars

International Nuclear Information System (INIS)

Leep, E.M.

1982-01-01

The author has analyzed high-dispersion spectra of over 100 WN stars in the Galaxy and the Large Magellenic Cloud (LMC). Most of the spectra were obtained through 4-m telescopes (Conti, Leep, and Perry 1981). The measured strengths of the WN classification lines N III lambdalambda4634-41, N IV lambda4057, N V lambda4604 (Smith 1968) for stars on WN subtypes 2.5-8 are shown. The assignments of WN subtypes are based on visual estimates of ratios of line strengths according to the scheme of Smith (1968), except that stars appearing to be earlier than WN3 are classified as WN2 or WN2.5 as explained by van der Hucht et al. (1981) and by Conti, Leep and Perry (1981). (Auth.)

Use of the babinet compensator for anomalous dispersion measurements.

Science.gov (United States)

Izatt, J R; Boyle, L J

1973-01-01

Reorientation of the optical elements in a standard experimental setup that utilizes a Babinet compensator to measure the anomalous dispersion of a birefringent mediumn results in a useful trade-off between the intensity and visibility of the polarization fringes produced by the apparatus. The fringe pattern is analyzed and numerical results are presented that illustrate the nature of the trade-off and its application to measurements near the center of a strong absorption line.

Model investigations on the longitudinal and transversal hydrodynamic dispersion of tracer solutions on porous media

International Nuclear Information System (INIS)

Klotz, D.; Moser, H.

1980-01-01

The object of the research project is to assess the hydrodynamic dispersion of labelling material solutions in special ground water lines based on measurements of the ground water flow rate and on the sedimentological properties of the natural ground water line present. The investigations were carried out in the laboratory in a three-dimensional ground water flow model and in column systems with HTO as tracer. (orig./HP) [de

Impact localization in dispersive waveguides based on energy-attenuation of waves with the traveled distance

Science.gov (United States)

Alajlouni, Sa'ed; Albakri, Mohammad; Tarazaga, Pablo

2018-05-01

An algorithm is introduced to solve the general multilateration (source localization) problem in a dispersive waveguide. The algorithm is designed with the intention of localizing impact forces in a dispersive floor, and can potentially be used to localize and track occupants in a building using vibration sensors connected to the lower surface of the walking floor. The lower the wave frequencies generated by the impact force, the more accurate the localization is expected to be. An impact force acting on a floor, generates a seismic wave that gets distorted as it travels away from the source. This distortion is noticeable even over relatively short traveled distances, and is mainly caused by the dispersion phenomenon among other reasons, therefore using conventional localization/multilateration methods will produce localization error values that are highly variable and occasionally large. The proposed localization approach is based on the fact that the wave's energy, calculated over some time window, decays exponentially as the wave travels away from the source. Although localization methods that assume exponential decay exist in the literature (in the field of wireless communications), these methods have only been considered for wave propagation in non-dispersive media, in addition to the limiting assumption required by these methods that the source must not coincide with a sensor location. As a result, these methods cannot be applied to the indoor localization problem in their current form. We show how our proposed method is different from the other methods, and that it overcomes the source-sensor location coincidence limitation. Theoretical analysis and experimental data will be used to motivate and justify the pursuit of the proposed approach for localization in a dispersive medium. Additionally, hammer impacts on an instrumented floor section inside an operational building, as well as finite element model simulations, are used to evaluate the performance of

Dispersions of attractive semiflexible fiberlike colloidal particles from bacterial cellulose microfibrils.

Science.gov (United States)

Kuijk, Anke; Koppert, Remco; Versluis, Peter; van Dalen, Gerard; Remijn, Caroline; Hazekamp, Johan; Nijsse, Jaap; Velikov, Krassimir P

2013-11-26

We prepared dispersions from bacterial cellulose microfibrils (CMF) of a commercial Nata de Coco source. We used an ultra-high-energy mechanical deagglomeration process that is able to disperse the CMFs from the pellicle in which they are organized in an irregular network. Because of the strong attractions between the CMFs, the dispersion remained highly heterogeneous, consisting of fiber bundles, flocs, and voids spanning tens to hundreds of micrometers depending on concentration. The size of these flocs increased with CMF concentration, the size of the bundles stayed constant, and the size of the voids decreased. The observed percolation threshold in MFC dispersions is lower than the theoretical prediction, which is accounted for by the attractive interactions in the system. Because bacterial cellulose is chemically very pure, it can be used to study the interaction of attractive and highly shape-anisotropic, semiflexible fiberlike colloidal particles.

Consequences of dispersal of a radioactive source

International Nuclear Information System (INIS)

Chester, R.O.; Chester, C.V.

1978-01-01

The purpose of this study is to examine the question of whether the risk and consequences of theft or sabotage of facilities or vehicles containing small quantities of SNM, source, and by-product materials are such that licensees should be required to adopt further measures to safeguard them. In the course of the study an assessment will be made of the potential consequences of malevolent use of the referenced materials. To provide, these will be compared with the corresponding characteristics of non-nuclear materials such as chemical or biological agents

Methods for calculating population dose from atmospheric dispersion of radioactivity

Energy Technology Data Exchange (ETDEWEB)

Cohen, B L; Jow, H N; Lee, I S [Pittsburgh Univ., PA (USA)

1978-06-01

Curves are computed from which population dose (man-rem) due to dispersal of radioactivity from a point source can be calculated in the gaussian plume model by simple multiplication, and methods of using them and their limitations are considered. Illustrative examples are presented.

Effects of chemical dispersants on oil physical properties and dispersion. Volume 1

International Nuclear Information System (INIS)

Khelifa, A.; Fingas, M.; Hollebone, B.P.; Brown, C.E.; Pjontek, D.

2007-01-01

Laboratory and field testing have shown that the dispersion of oil spilled in water is influenced by chemical dispersants via the modification of the interfacial properties of the oil, such as oil-brine interfacial tension (IFT). This study focused on new laboratory experiments that measured the effects on the physical properties and dispersion of oil, with particular reference to the effects of chemical dispersants on IFT and oil viscosity and the subsequent effects on oil droplet formation. Experiments were conducted at 15 degrees C using Arabian Medium, Alaska North Slope and South Louisiana crude and Corexit 9500 and Corexit 9527 chemical dispersants. The dispersants were denser than the 3 oils. The effect of IFT reduction on oil dispersion was measured and showed substantial reduction in the size and enhancement of the concentration of oil droplets in the water column. It was shown that the brine-oil IFT associated with the 3 crudes reduced to less than 3.6 mN/m with the application of the chemical dispersants, even at a low dispersant-to-oil ratio (DOR) value of 1:200. The use of chemical dispersants increased the viscosity of the dispersant-oil mixture up to 40 per cent over the neat crude oil. It was shown that for each mixing condition, an optimum value of DOR exists that provides for maximal dispersant effectiveness. The IFT reaches maximum reduction at optimum DOR. It was suggested that oil spill modelling can be improved with further study of IFT reduction with DOR and variations of critical micelle concentration with the type and solubility of chemical dispersant, oil type and oil to water ratio. 13 refs., 3 tabs., 7 figs

Removal of power line interference of space bearing vibration signal based on the morphological filter and blind source separation

Science.gov (United States)

Dong, Shaojiang; Sun, Dihua; Xu, Xiangyang; Tang, Baoping

2017-06-01

Aiming at the problem that it is difficult to extract the feature information from the space bearing vibration signal because of different noise, for example the running trend information, high-frequency noise and especially the existence of lot of power line interference (50Hz) and its octave ingredients of the running space simulated equipment in the ground. This article proposed a combination method to eliminate them. Firstly, the EMD is used to remove the running trend item information of the signal, the running trend that affect the signal processing accuracy is eliminated. Then the morphological filter is used to eliminate high-frequency noise. Finally, the components and characteristics of the power line interference are researched, based on the characteristics of the interference, the revised blind source separation model is used to remove the power line interferences. Through analysis of simulation and practical application, results suggest that the proposed method can effectively eliminate those noise.

Emission, Dispersion, Transformation, and Deposition of Asian Particulates Over the Western Pacific Ocean. Part II

International Nuclear Information System (INIS)

Turco, Richard P.

2005-01-01

In this project we developed and applied a coupled three-dimensional meteorology/chemistry/microphysics model to study the patterns of aerosol dispersion and deposition in the western Pacific area; carried out a series of detailed regional aerosol simulations to test the ability of models to treat emission, dispersion and removal processes prior to long-range transport; calculated and analyzed trajectories that originate in Asian dust source regions and reach the Pacific Basin; performed detailed simulations of regional and trans-Pacific transport, as well as the microphysical and chemical properties, of aerosols in the Asia-Pacific region to quantify processes that control the emission, dispersion and removal of particles; and assessed the contributions of regional-scale Asian particulate sources to the deposition of pollutants onto surface waters. The transport and deposition of aerosols and vapors were found to be strongly controlled by large and synoptic scale meteorology, convection, turbulence, and precipitation, as well as strong interactions between surface conditions and topographical features. The present analysis suggests that accurate representations of aerosol sources, transport and deposition can be obtained using a comprehensive modeling approach

Overview of the Conceptual Design of the Future VENUS Neutron Imaging Beam Line at the Spallation Neutron Source

Science.gov (United States)

Bilheux, Hassina; Herwig, Ken; Keener, Scott; Davis, Larry

VENUS (Versatile Neutron Imaging Beam line at the Spallation Neutron Source) will be a world-class neutron-imaging instrument that will uniquely utilize the Spallation Neutron Source (SNS) time-of-flight (TOF) capabilities to measure and characterize objects across several length scales (mm to μm). When completed, VENUS will provide academia, industry and government laboratories with the opportunity to advance scientific research in areas such as energy, materials, additive manufacturing, geosciences, transportation, engineering, plant physiology, biology, etc. It is anticipated that a good portion of the VENUS user community will have a strong engineering/industrial research focus. Installed at Beam line 10 (BL10), VENUS will be a 25-m neutron imaging facility with the capability to fully illuminate (i.e., umbra illumination) a 20 cm x 20 cm detector area. The design allows for a 28 cm x 28 cm field of view when using the penumbra to 80% of the full illumination flux. A sample position at 20 m will be implemented for magnification measurements. The optical components are comprised of a series of selected apertures, T0 and bandwidth choppers, beam scrapers, a fast shutter to limit sample activation, and flight tubes filled with Helium. Techniques such as energy selective, Bragg edge and epithermal imaging will be available at VENUS.

Building-Resolved CFD Simulations for Greenhouse Gas Transport and Dispersion over Washington DC / Baltimore

Science.gov (United States)

Prasad, K.; Lopez-Coto, I.; Ghosh, S.; Mueller, K.; Whetstone, J. R.

2015-12-01

The North-East Corridor project aims to use a top-down inversion methodology to quantify sources of Greenhouse Gas (GHG) emissions over urban domains such as Washington DC / Baltimore with high spatial and temporal resolution. Atmospheric transport of tracer gases from an emission source to a tower mounted receptor are usually conducted using the Weather Research and Forecasting (WRF) model. For such simulations, WRF employs a parameterized turbulence model and does not resolve the fine scale dynamics generated by the flow around buildings and communities comprising a large city. The NIST Fire Dynamics Simulator (FDS) is a computational fluid dynamics model that utilizes large eddy simulation methods to model flow around buildings at length scales much smaller than is practical with WRF. FDS has the potential to evaluate the impact of complex urban topography on near-field dispersion and mixing difficult to simulate with a mesoscale atmospheric model. Such capabilities may be important in determining urban GHG emissions using atmospheric measurements. A methodology has been developed to run FDS as a sub-grid scale model within a WRF simulation. The coupling is based on nudging the FDS flow field towards that computed by WRF, and is currently limited to one way coupling performed in an off-line mode. Using the coupled WRF / FDS model, NIST will investigate the effects of the urban canopy at horizontal resolutions of 10-20 m in a domain of 12 x 12 km. The coupled WRF-FDS simulations will be used to calculate the dispersion of tracer gases in the North-East Corridor and to evaluate the upwind areas that contribute to tower observations, referred to in the inversion community as influence functions. Results of this study will provide guidance regarding the importance of explicit simulations of urban atmospheric turbulence in obtaining accurate estimates of greenhouse gas emissions and transport.

Dispersion surfaces and ion wave instabilities in space plasmas

International Nuclear Information System (INIS)

Andre, M

1985-08-01

In this thesis, the dispersion relation of linear waves in a non-relativistic, collisionless and homogeneous plasma in a uniform magnetic field, is solved numerically. Both electrostatic and elecromagnetic waves with frequencies from below the ion gyrofrequency to above the electron gyrofrequency are studied for all angles of propagation. Modes occurring in a cold plasma as well as waves dependent on thermal effects are included. Dispersion surfaces, that is plots of frequency versus wavevector components, are presented for some models of space plasmas. Waves with frequencies of the order of the ion gyrofrequency (ion waves), are well known to exist in space plasmas. In this thesis, the generation of ion waves by ion distributions with loss-cones or temperature anisotropies, or by beams of charged particles, is investigated by numerical methods. Effects of heavy ions are considered. Dispersion surfaces and analytical arguments are used to clarify the results. It is shown that particle beams and ion loss-cone distributions can generate electrostatic ion waves, even when a significant amount of the electrons are cool. These calculations are in agreement with simultaneous observatons of waves and particles obtained by a satellite on auroral field lines. (author)

Removal of Disperse Blue 56 and Disperse Red 135 dyes from aqueous dispersions by modified montmorillonite nanoclay

Directory of Open Access Journals (Sweden)

Ahmadishoar Javad

2017-01-01

Full Text Available In this study modified montmorillonite was used as an adsorbent for the removal of two selected disperse dyes i.e., Disperse Blue 56 (DB and Disperse Red 135 (DR from dye dispersions. The adsorption equilibrium data of dyes adsorption were investigated by using Nernst, Freundlich and Langmuir isotherm models. The adsorption kinetics was analyzed by using different models including pseudo-first-order, pseudo-second-order, Elovich and Intraparticle diffusion model. The Freundlich isotherm was found to be the most appropriate model for describing the sorption of the dyes on modified nanoclay. The best fit to the experimental results was obtained by using the pseudo-second-order kinetic equation, which satisfactorily described the process of dye adsorption. Although different kinetic models may control the rate of the adsorption process, the results indicated that the main rate limiting step was the intraparticle diffusion. The results showed that the proposed modified montmorillonite could be used as an effective adsorbent for the removal of disperse dyes even from highly concentrated dispersions.

Simulation of a low energy beam transport line

International Nuclear Information System (INIS)

Yang Yao; Liu Zhanwen; Zhang Wenhui; Ma Hongyi; Zhang Xuezhen; Zhao Hongwei; Yao Ze'en

2012-01-01

A 2.45 GHz electron cyclotron resonance intense proton source and a low energy beam transport line with dual-Glaser lens were designed and fabricated by Institute of Modern Physics for a compact pulsed hadron source at Tsinghua. The intense proton beams extracted from the ion source are transported through the transport line to match the downstream radio frequency quadrupole accelerator. Particle-in-cell code BEAMPATH was used to carry out the beam transport simulations and optimize the magnetic field structures of the transport line. Emittance growth due to space charge and spherical aberrations of the Glaser lens were studied in both theory and simulation. The results show that narrow beam has smaller aberrations and better beam quality through the transport line. To better match the radio frequency quadrupole accelerator, a shorter transport line is desired with sufficient space charge neutralization. (authors)

A comparison of dispersing media for various engineered carbon nanoparticles

Directory of Open Access Journals (Sweden)

Holian Andrij

2007-07-01

Full Text Available Abstract Background With the increased manufacture and use of carbon nanoparticles (CNP there has been increasing concern about the potential toxicity of fugitive CNP in the workplace and ambient environment. To address this matter a number of investigators have conducted in vitro and in vivo toxicity assessments. However, a variety of different approaches for suspension of these particles (culture media, Tween 80, dimethyl sulfoxide, phosphate-buffered saline, fetal calf serum, and others, and different sources of materials have generated potentially conflicting outcomes. The quality of the dispersion of nanoparticles is very dependent on the medium used to suspend them, and this then will most likely affect the biological outcomes. Results In this work, the distributions of different CNP (sources and types have been characterized in various media. Furthermore, the outcome of instilling the different agglomerates, or size distributions, was examined in mouse lungs after one and seven days. Our results demonstrated that CNP suspended in serum produced particle suspensions with the fewest large agglomerates, and the most uniform distribution in mouse lungs. In addition, no apparent clearance of instilled CNP took place from lungs even after seven days. Conclusion This work demonstrates that CNP agglomerates are present in all dispersing vehicles to some degree. The vehicle that contains some protein, lipid or protein/lipid component disperses the CNP best, producing fewer large CNP agglomerates. In contrast, vehicles absent of lipid and protein produce the largest CNP agglomerates. The source of the CNP is also a factor in the degree of particle agglomeration within the same vehicle.

A model for long-distance dispersal of boll weevils (Coleoptera: Curculionidae)

Science.gov (United States)

Westbrook, John K.; Eyster, Ritchie S.; Allen, Charles T.

2011-07-01

The boll weevil, Anthonomus grandis (Boheman), has been a major insect pest of cotton production in the US, accounting for yield losses and control costs on the order of several billion US dollars since the introduction of the pest in 1892. Boll weevil eradication programs have eliminated reproducing populations in nearly 94%, and progressed toward eradication within the remaining 6%, of cotton production areas. However, the ability of weevils to disperse and reinfest eradicated zones threatens to undermine the previous investment toward eradication of this pest. In this study, the HYSPLIT atmospheric dispersion model was used to simulate daily wind-aided dispersal of weevils from the Lower Rio Grande Valley (LRGV) of southern Texas and northeastern Mexico. Simulated weevil dispersal was compared with weekly capture of weevils in pheromone traps along highway trap lines between the LRGV and the South Texas / Winter Garden zone of the Texas Boll Weevil Eradication Program. A logistic regression model was fit to the probability of capturing at least one weevil in individual pheromone traps relative to specific values of simulated weevil dispersal, which resulted in 60.4% concordance, 21.3% discordance, and 18.3% ties in estimating captures and non-captures. During the first full year of active eradication with widespread insecticide applications in 2006, the dispersal model accurately estimated 71.8%, erroneously estimated 12.5%, and tied 15.7% of capture and non-capture events. Model simulations provide a temporal risk assessment over large areas of weevil reinfestation resulting from dispersal by prevailing winds. Eradication program managers can use the model risk assessment information to effectively schedule and target enhanced trapping, crop scouting, and insecticide applications.

Coupling of WRF and Building-resolved CFD Simulations for Greenhouse Gas Transport and Dispersion

Science.gov (United States)

Prasad, K.; Hu, H.; McDermott, R.; Lopez-Coto, I.; Davis, K. J.; Whetstone, J. R.; Lauvaux, T.

2014-12-01

The Indianapolis Flux Experiment (INFLUX) aims to use a top-down inversion methodology to quantify sources of Greenhouse Gas (GHG) emissions over an urban domain with high spatial and temporal resolution. Atmospheric transport of tracer gases from an emission source to a tower mounted receptor are usually conducted using the Weather Research and Forecasting (WRF) model. WRF is used extensively in the atmospheric community to simulate mesoscale atmospheric transport. For such simulations, WRF employs a parameterized turbulence model and does not resolve the fine scale dynamics that are generated by the flow around buildings and communities that are part of a large city. Since the model domain includes the city of Indianapolis, much of the flow of interest is over an urban topography. The NIST Fire Dynamics Simulator (FDS) is a computational fluid dynamics model to perform large eddy simulations of flow around buildings, but it has not been nested within a larger-scale atmospheric transport model such as WRF. FDS has the potential to evaluate the impact of complex urban topography on near-field dispersion and mixing that cannot be simulated with a mesoscale atmospheric model, and which may be important to determining urban GHG emissions using atmospheric measurements. A methodology has been developed to run FDS as a sub-grid scale model within a WRF simulation. The coupling is based on nudging the FDS flow field towards the one computed by WRF, and is currently limited to one way coupling performed in an off-line mode. Using the coupled WRF / FDS model, NIST will investigate the effects of the urban canopy at horizontal resolutions of 2-10 m. The coupled WRF-FDS simulations will be used to calculate the dispersion of tracer gases in an urban domain and to evaluate the upwind areas that contribute to tower observations, referred to in the inversion community as influence functions. Predicted mixing ratios will be compared with tower measurements and WRF simulations

THz Wave Propagation on Strip Lines: Devices, Properties, and Applications

Directory of Open Access Journals (Sweden)

Y. Kadoya

2008-06-01

Full Text Available We report the propagation characteristics of THz pulses on micro-strip-lines and coplanar strip-lines, in which low permittivity polymer materials are used as the dielectric layer or the substrate. As a result of the low attenuation and small dispersion in the devices, the spectral width up to 3 THz can be achieved even after the 1 mm propagation. Spectroscopic characterizations of liquid or powder specimens are demonstrated using the devices. We also show a possibility of realizing a very low attenuation using a quadrupole mode in three strip coplanar lines on the polymer substrate.

Nonlinear dispersion-based incoherent photonic processing for microwave pulse generation with full reconfigurability.

Science.gov (United States)

Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

2012-03-12

A novel all-optical technique based on the incoherent processing of optical signals using high-order dispersive elements is analyzed for microwave arbitrary pulse generation. We show an approach which allows a full reconfigurability of a pulse in terms of chirp, envelope and central frequency by the proper control of the second-order dispersion and the incoherent optical source power distribution, achieving large values of time-bandwidth product.

Characteristics of air pollutant dispersion around a high-rise building

International Nuclear Information System (INIS)

Zhang, Y.; Kwok, K.C.S.; Liu, X.-P.; Niu, J.-L.

2015-01-01

A numerical wind tunnel model was proposed. The computed results of the pollutant diffusion around a typical Hong Kong high-rise building model (at a linear scale of 1:30), were found to show a similar trend to the outcomes of self-conducted experimental measurements that the pathways of pollutant migration for windward and leeward pollutant emission are different. For the case with windward pollutant emission at the 3rd floor within a re-entry, the pollutant migrated downwards due to the downwash created by the wind. In contrast, for the case with leeward pollution emission, dispersion is dominated by intense turbulent mixing in the near wake and characterized by the upward migration of the pollutant in the leeward re-entry. The simulated results of haze-fog (HF) studies confirm that the pathway of pollutant migration is dominated by wind–structure interaction and buoyancy effect only plays a minor role in the dispersion process. - Highlights: • A self-developed numerical wind tunnel model was proposed. • Characteristics of air pollutant dispersion with windward/leeward emission were discussed. • Wind–structure interaction controls the air pollutant dispersion around the building. - The different characteristics of air pollutant dispersion around a high-rise building, for both cases of a dispersion source in either the windward face or leeward face, are dominated by wind–structure interaction, with buoyancy effect playing only a minor role

DISSECTING THE POWER SOURCES OF LOW-LUMINOSITY EMISSION-LINE GALAXY NUCLEI VIA COMPARISON OF HST-STIS AND GROUND-BASED SPECTRA

Energy Technology Data Exchange (ETDEWEB)

Constantin, Anca; Castillo, Christopher A. [Department of Physics and Astronomy, James Madison University, Harrisonburg, VA 22807 (United States); Shields, Joseph C. [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Barth, Aaron J. [Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

2015-12-01

Using a sample of ∼100 nearby line-emitting galaxy nuclei, we have built the currently definitive atlas of spectroscopic measurements of Hα and neighboring emission lines at subarcsecond scales. We employ these data in a quantitative comparison of the nebular emission in Hubble Space Telescope (HST) and ground-based apertures, which offer an order-of-magnitude difference in contrast, and provide new statistical constraints on the degree to which transition objects and low-ionization nuclear emission-line regions (LINERs) are powered by an accreting black hole at ≲10 pc. We show that while the small-aperture observations clearly resolve the nebular emission, the aperture dependence in the line ratios is generally weak, and this can be explained by gradients in the density of the line-emitting gas: the higher densities in the more nuclear regions potentially flatten the excitation gradients, suppressing the forbidden emission. The transition objects show a threefold increase in the incidence of broad Hα emission in the high-resolution data, as well as the strongest density gradients, supporting the composite model for these systems as accreting sources surrounded by star-forming activity. The narrow-line LINERs appear to be the weaker counterparts of the Type 1 LINERs, where the low accretion rates cause the disappearance of the broad-line component. The enhanced sensitivity of the HST observations reveals a 30% increase in the incidence of accretion-powered systems at z ≈ 0. A comparison of the strength of the broad-line emission detected at different epochs implies potential broad-line variability on a decade-long timescale, with at least a factor of three in amplitude.

Reliability benefits of dispersed wind resource development

International Nuclear Information System (INIS)

Milligan, M.; Artig, R.

1998-05-01

Generating capacity that is available during the utility peak period is worth more than off-peak capacity. Wind power from a single location might not be available during enough of the peak period to provide sufficient value. However, if the wind power plant is developed over geographically disperse locations, the timing and availability of wind power from these multiple sources could provide a better match with the utility's peak load than a single site. There are other issues that arise when considering disperse wind plant development. Singular development can result in economies of scale and might reduce the costs of obtaining multiple permits and multiple interconnections. However, disperse development can result in cost efficiencies if interconnection can be accomplished at lower voltages or at locations closer to load centers. Several wind plants are in various stages of planning or development in the US. Although some of these are small-scale demonstration projects, significant wind capacity has been developed in Minnesota, with additional developments planned in Wyoming, Iowa and Texas. As these and other projects are planned and developed, there is a need to perform analysis of the value of geographically disperse sites on the reliability of the overall wind plant.This paper uses a production-cost/reliability model to analyze the reliability of several wind sites in the state of Minnesota. The analysis finds that the use of a model with traditional reliability measures does not produce consistent, robust results. An approach based on fuzzy set theory is applied in this paper, with improved results. Using such a model, the authors find that system reliability can be optimized with a mix of disperse wind sites

Genetic diversity of dispersed seeds is highly variable among leks of the long-wattled umbrellabird

Science.gov (United States)

Ottewell, Kym; Browne, Luke; Cabrera, Domingo; Olivo, Jorge; Karubian, Jordan

2018-01-01

Frugivorous animals frequently generate clumped distributions of seeds away from source trees, but genetic consequences of this phenomenon remain poorly resolved. Seed dispersal of the palm Oenocarpus bataua by long-wattled umbrellabirds Cephalopterus penduliger generates high seed densities in leks (i.e., multi-male display sites), providing a suitable venue to investigate how dispersal by this frugivore may influence seed source diversity and genetic structure at local and landscape levels. We found moderate levels of maternal seed source diversity in primary seed rain across five leks in northwest Ecuador (unweighted mean alpha diversity α = 9.52, weighted mean αr = 3.52), with considerable variation among leks (αr range: 1.81-24.55). Qualitatively similar findings were obtained for allelic diversity and heterozygosity. Higher densities of O. bataua adults around leks were associated with higher values of αr and heterozygosity (non-significant trends) and allelic diversity (significant correlation). Seed source overlap between different leks was not common but did occur at low frequency, providing evidence for long-distance seed dispersal by umbrellabirds into leks. Our findings are consistent with the idea that seed pool diversity within leks may be shaped by the interaction between density of local trees, which can vary considerably between leks, and umbrellabird foraging ecology, particularly a lack of territorial defense of fruiting trees. Taken as a whole, this work adds to our growing appreciation of the ways resource distribution and associated frugivore foraging behaviors mechanistically shape seed dispersal outcomes and the distribution of plant genotypes across the landscape.

Actively Controlling the Topological Transition of Dispersion Based on Electrically Controllable Metamaterials

Directory of Open Access Journals (Sweden)

Zhiwei Guo

2018-04-01

Full Text Available Topological transition of the iso-frequency contour (IFC from a closed ellipsoid to an open hyperboloid provides unique capabilities for controlling the propagation of light. However, the ability to actively tune these effects remains elusive, and the related experimental observations are highly desirable. Here, a tunable electric IFC in a periodic structure composed of graphene/dielectric multilayers is investigated by tuning the chemical potential of the graphene layer. Specially, we present the actively controlled transportation in two kinds of anisotropic zero-index media containing perfect electric conductor/perfect magnetic conductor impurities. Finally, by adding variable capacitance diodes into a two-dimensional transmission-line system, we present an experimental demonstration of the actively controlled magnetic topological transition of dispersion based on electrically controllable metamaterials. With the increase in voltage, we measure the different emission patterns from a point source inside the structure and observe the phase-transition process of IFCs. The realization of an actively tuned topological transition will open up a new avenue in the dynamical control of metamaterials.

A model for dispersion of contaminants in the subway environment

Energy Technology Data Exchange (ETDEWEB)

Coke, L. R.; Sanchez, J. G.; Policastro, A. J.

2000-05-03

Although subway ventilation has been studied extensively, very little has been published on dispersion of contaminants in the subway environment. This paper presents a model that predicts dispersion of contaminants in a complex subway system. It accounts for the combined transient effects of train motion, station airflows, train car air exchange rates, and source release properties. Results are presented for a range of typical subway scenarios. The effects of train piston action and train car air exchange are discussed. The model could also be applied to analyze the environmental impact of hazardous materials releases such as chemical and biological agents.

Dense gas dispersion in the atmosphere

Energy Technology Data Exchange (ETDEWEB)

Nielsen, Morten

1998-09-01

Dense gas dispersion is characterized by buoyancy induced gravity currents and reduction of the vertical mixing. Liquefied gas releases from industrial accidents are cold because of the heat of evaporation which determines the density for a given concentration and physical properties. The temperature deficit is moderated by the heat flux from the ground, and this convection is an additional source of turbulence which affects the mixing. A simple model as the soil heat flux is used to estimate the ability of the ground to sustain the heat flux during release. The initial enthalpy, release rate, initial entrainment and momentum are discussed for generic source types and the interaction with obstacles is considered. In the MTH project BA experiments source with and without momentum were applied. The continuously released propane gas passed a two-dimensional removable obstacle perpendicular to the wind direction. Ground-level gas concentrations and vertical profiles of concentration, temperature, wind speed and turbulence were measured in front of and behind the obstacle. Ultrasonic anemometers providing fast velocity and concentration signals were mounted at three levels on the masts. The observed turbulence was influenced by the stability and the initial momentum of the jet releases. Additional information were taken from the `Dessert tortoise` ammonia jet releases, from the `Fladis` experiment with transition from dense to passive dispersion, and from the `Thorney Island` continuous releases of isothermal freon mixtures. The heat flux was found to moderate the negative buoyancy in both the propane and ammonia experiments. The heat flux measurements are compared to an estimate by analogy with surface layer theory. (au) 41 tabs., 146 ills., 189 refs.

Dispersion Engineering of Bose-Einstein Condensates

Science.gov (United States)

Khamehchi, Mohammad Amin

The subject of this dissertation is engineering the dispersion relation for dilute Bose-Einstein condensates (BECs). When a BEC is immersed into suitably tailored laser fields its dispersion can be strongly modified. Prominent examples for such laser fields include optical lattice geometries and Raman dressing fields. The ability to engineer the dispersion of a BEC allows for the investigation of a range of phenomena related to quantum hydrodynamics and condensed matter. In the first context, this dissertation studies the excitation spectrum of a spin-orbit coupled (SOC) BEC. The spin-orbit coupling is generated by " dressing" the atoms with two Raman laser fields. The excitation spectrum has a Roton-like feature that can be altered by tuning the Raman laser parameters. It is demonstrated that the Roton mode can be softened, but it does not reach the ground state energy for the experimental conditions we had. Furthermore, the expansion of SOC BECs in 1D is studied by relaxing the trap allowing the BEC to expand in the SOC direction. Contrary to the findings for optical lattices, it is observed that the condensate partially occupies quasimomentum states with negative effective mass, and therefore an abrupt deceleration is observed although the mean field force is along the direction of expansion. In condensed-matter systems, a periodic lattice structure often plays an important role. In this context, an alternative to the Raman dressing scheme can be realized by coupling the s- and p- bands of a static optical lattice via a weak moving lattice. The bands can be treated as pseudo-spin states. It is shown that similar to the dispersion relation of a Raman dressed SOC, the quasimomentum of the ground state is different from zero. Coherent coupling of the SOC dispersion minima can lead to the realization of the stripe phase even though it is not the thermodynamic ground state of the system. Along the lines of studying the hydrodynamics of BECs, three novel

Dispersion and betatron matching into the linac

International Nuclear Information System (INIS)

Decker, F.J.; Adolphsen, C.; Corbett, W.J.; Emma, P.; Hsu, I.; Moshammer, H.; Seeman, J.T.; Spence, W.L.

1991-05-01

In high energy linear colliders, the low emittance beam from a damping ring has to be preserved all the way to the linac, in the linac and to the interaction point. In particular, the Ring-To-Linac (RTL) section of the SLAC Linear Collider (SLC) should provide an exact betatron and dispersion match from the damping ring to the linac. A beam with a non-zero dispersion shows up immediately as an increased emittance, while with a betatron mismatch the beam filaments in the linac. Experimental tests and tuning procedures have shown that the linearized beta matching algorithms are insufficient if the actual transport line has some unknown errors not included in the model. Also, adjusting quadrupole strengths steers the beam if it is offset in the quadrupole magnets. These and other effects have lead to a lengthy tuning process, which in the end improves the matching, but is not optimal. Different ideas will be discussed which should improve this matching procedure and make it a more reliable, faster and simpler process. 5 refs., 2 figs

[Literature review of the dispersal of transgenes from genetically modified maize].

Science.gov (United States)

Ricroch, Agnès; Bergé, Jean Baptiste; Messéan, Antoine

2009-10-01

This article aims at reviewing the theoretical and experimental data published in 562 publications referring to genetically modified (GM) maize dispersal. Our choice was limited to this since in the European Union (EU), GM maize is the only GM crop currently grown commercially. The pollen dispersal of transgenic maize is due to two factors: (i) pollen-mediated gene flow; (ii) seed admixture during harvest and post-harvest processes. The pollen dispersal decreases rapidly with the distance from GM plots. Climatic and topographic factors and factors of relative density between GM and non-GM maize plots impact on the pollen dispersal. The combination of both isolation distance and flowering date between source plots and sink plots limits the adventitious presence of transgenes in non-GM plots. All publications we reviewed demonstrate that the EU 0.9% threshold is technically manageable if the measures of isolation distances as well as harvesting and post harvesting processes and fully synchronous flowering are implemented.

On the Sensitivity of Neutrino Telescopes to a Modified Dispersion Relation

International Nuclear Information System (INIS)

Bustamante, M.; Gago, A. M.; Bazo, J. L.; Miranda, O. G.

2008-01-01

We consider a modified dispersion relation and its effect on the flavour ratios of high-energy neutrinos originated at distant astrophysical sources such as active galactic nuclei. This dispersion relation arise naturally in different new physics (NP) effects such as violation of CPT invariance, of the equivalence principle and of Lorentz invariance. It is a common notion in the literature that by using the flux of high-energy neutrinos expected from distant astrophysical sources, the sensitivity to possible NP effects may be improved beyond the current bounds. However, performing a realistic analysis that takes into account the expected number of events in future neutrino telescopes, we find that the average detected flavour ratios with and without the inclusion of new physics have essentially the same value, making difficult to obtain an improved bound for this type of new physics

Spatially Extended and High-Velocity Dispersion Molecular Component in Spiral Galaxies: Single-Dish Versus Interferometric Observations

Science.gov (United States)

Caldú-Primo, Anahi; Schruba, Andreas; Walter, Fabian; Leroy, Adam; Bolatto, Alberto D.; Vogel, Stuart

2015-02-01

Recent studies of the molecular medium in nearby galaxies have provided mounting evidence that the molecular gas can exist in two phases: one that is clumpy and organized as molecular clouds and another one that is more diffuse. This last component has a higher velocity dispersion than the clumpy one. In order to investigate these two molecular components further, we compare the fluxes and line widths of CO in NGC 4736 and NGC 5055, two nearby spiral galaxies for which high-quality interferometric as well as single-dish data sets are available. Our analysis leads to two main results: (1) employing three different methods, we determine the flux recovery of the interferometer as compared to the single-dish to be within a range of 35%-74% for NGC 4736 and 81%-92% for NGC 5055, and (2) when focusing on high (S/N ≥ 5) lines of sight (LOSs), the single-dish line widths are larger by ˜(40 ± 20)% than the ones derived from interferometric data, which is in agreement with stacking all LOSs. These results point to a molecular gas component that is distributed over spatial scales larger than 30″(˜1 kpc), and is therefore filtered out by the interferometer. The available observations do not allow us to distinguish between a truly diffuse gas morphology and a uniform distribution of small clouds that are separated by less than the synthesized beam size (˜3″ or ˜100 pc), as they would both be invisible for the interferometer. This high velocity dispersion component has a dispersion similar to what is found in the atomic medium, as traced through observations of the H i line.

Mobile-Source GHG Modeling Institutions and Capacities in China:Findings Based on Structured Interviews and On-Line Surveys

Institute of Scientific and Technical Information of China (English)

Jiangping; ZHOU; Yin; WANG

2014-01-01

This paper provides an overview of practices of mobile-source greenhouse gas(GHG) modeling in China and related data sharing issues. It is based on structured phone interviews and two on-line surveys conducted in 2011 and finds that most cities have transportation-land use models but that few have mobile-source GHG models. A group of entities housed in the government have the strongest GHG modeling capacities and dominate the relevant consulting market. Data hoarding of public entities is the biggest barrier for entities without government ties to compete in the market. The reasons for data hoarding include government concerns over political implications of data release, a tradition of data hoarding, and a lack of confidence in reliability and accuracy of the data.

Orphan sources and the challenges: requirement for the prevention of malevolent use of radioactive sources and preparedness for radiological emergencies

International Nuclear Information System (INIS)

Pradeepkumar, K.S.; Sharma, D.N.

2006-01-01

Challenges from smuggled or illegally transported radioactive sources with intention of causing threats to the society are similar to the radiological emergencies possible from misplaced/lost radioactive sources. While large number of radioactive sources are transported and are in use world over, the emergency preparedness and response system is not adequately developed compared to that for nuclear facilities. After the terrorist attack on W.T.C., there is concern world over about the malicious use of radioactive material calling for improving the emergency response system and international cooperation for preventing illicit trafficking of radioactive sources/material. Extremely sensitive state-of-the art monitoring systems installed at appropriate locations and periodic mobile radiation monitoring around suspected areas can be deterrent and can prevent the illicit trafficking of radioactive sources. Unless every nation ensures strict administrative control over the sources and implement usage of state-of-the art systems and methodology for early detection/prevention of illegal movement of sources within the territory and across its boundaries, the challenges from the orphan sources will remain for ever. The issues and challenges of man made radiological emergencies, remedial measures and the methodology for prevention and management of such emergencies are discussed here. The threat from an orphan source depends on many parameters. The type and quantity of the radionuclide, physical and chemical form influencing dispersion in air, deposition, solubility, migration in soil etc., can vary the radiological consequences when the source gets crushed accidentally along with scrap or is used for malevolent purposes. Depending on the level of environmental contamination, long term effects of the radiological emergency can significantly vary. Development of capability for quick detection, assessment and response are essential if prevention of theft/misuse of such sources

Radiological Dispersion Devices: are we prepared?

Energy Technology Data Exchange (ETDEWEB)

Sohier, Alain [Decision Strategy Research Department (Radiation Protection Division), Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, B-2400 Mol (Belgium)]. E-mail: asohier@sckcen.be; Hardeman, Frank [Decision Strategy Research Department (Radiation Protection Division), Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, B-2400 Mol (Belgium)

2006-07-01

Already before the events of September 11th 2001 concern was raised about the spread of orphan sources and their potential use in Radiological Dispersion Devices by terrorist groups. Although most of the simulated scenarios foresee a rather limited direct health impact on the population, the affected region would suffer from the indirect consequences such as social disruption, cleanup requirements and economic costs. The nature of such a radiological attack would anyway be different compared to conventional radiological accidents, basically because it can happen anywhere at any time. Part of the response resides in a general preparedness scheme incorporating attacks with Radiological Dispersion Devices. Training of different potential intervention teams is essential. The response would consist of a prioritised list of actions adapted to the circumstances. As the psychosocial dimension of the crisis could be worse than the purely radiological one, an adapted communication strategy with the public aspect would be a key issue.

Radiological Dispersion Devices: are we prepared?

International Nuclear Information System (INIS)

Sohier, Alain; Hardeman, Frank

2006-01-01

Already before the events of September 11th 2001 concern was raised about the spread of orphan sources and their potential use in Radiological Dispersion Devices by terrorist groups. Although most of the simulated scenarios foresee a rather limited direct health impact on the population, the affected region would suffer from the indirect consequences such as social disruption, cleanup requirements and economic costs. The nature of such a radiological attack would anyway be different compared to conventional radiological accidents, basically because it can happen anywhere at any time. Part of the response resides in a general preparedness scheme incorporating attacks with Radiological Dispersion Devices. Training of different potential intervention teams is essential. The response would consist of a prioritised list of actions adapted to the circumstances. As the psychosocial dimension of the crisis could be worse than the purely radiological one, an adapted communication strategy with the public aspect would be a key issue

Dispersion in the wake of a model industrial complex

International Nuclear Information System (INIS)

Hatcher, R.V.; Meroney, R.N.; Peterka, J.A.; Kothari, K.

1977-06-01

Models (1:200 scale) of the EOCR reactor building and surrounding silo and tank buildings at the Idaho National Engineering Laboratory, Idaho Falls, Idaho were put into the Meteorological Wind Tunnel at Colorado State University for the purpose of studying the effects of building wakes on dispersion. Flow visualization was done and concentration measurements were taken. The test program consisted of systematic releases from ground, building height, and stack height sources with no appreciable plume rise. The program was repeated for cases of moderately unstable, neutral, moderately stable, and stable conditions in the wind tunnel. Results show that the buildings significantly alter the dispersion patterns and the addition of any extra buildings or slight terrain change in the immediate vicinity of the building has a major effect. In the near wake region the effects of stratification were still evident causing slightly higher concentrations for stable conditions and slightly lower for unstable. Current dispersion models are discussed and evaluated that predict concentrations in the building wake region

Inverse problems using ANN in long range atmospheric dispersion with signature analysis picked scattered numerical sensors from CFD

International Nuclear Information System (INIS)

Sharma, Pavan K.; Gera, B.; Ghosh, A.K.; Kushwaha, H.S.

2010-01-01

Scalar dispersion in the atmosphere is an important area wherein different approaches are followed in development of good analytical model. The analyses based on Computational Fluid Dynamics (CFD) codes offer an opportunity of model development based on first principles of physics and hence such models have an edge over the existing models. Both forward and backward calculation methods are being developed for atmospheric dispersion around NPPs at BARC Forward modeling methods, which describe the atmospheric transport from sources to receptors, use forward-running transport and dispersion models or computational fluid dynamics models which are run many times, and the resulting dispersion field is compared to observations from multiple sensors. Backward or inverse modeling methods use only one model run in the reverse direction from the receptors to estimate the upwind sources. Inverse modeling methods include adjoint and tangent linear models, Kalman filters, and variational data assimilation, and neural network. The present paper is aimed at developing a new approach where the identified specific signatures at receptor points form the basis for source estimation or inversions. This approach is expected to reduce the large transient data sets to reduced and meaningful data sets. In fact this reduces the inherently transient data set into a time independent mean data set. Forward computation were carried out with CFD code for various case to generate a large set of data to train the ANN. Specific signature analysis was carried out to find the parameters of interest for ANN training like peak concentration, time to reach peak concentration and time to fall, the ANN was trained with data and source strength and location were predicted from ANN. Inverse problem was performed using ANN approach in long range atmospheric dispersion. An illustration of application of CFD code for atmospheric dispersion studies for a hypothetical case is also included in the paper. (author)

Nanocomposites from Stable Dispersions of Carbon Nanotubes in Polymeric Matrices Using Dispersion Interaction

Science.gov (United States)

Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor)

2016-01-01

Stable dispersions of carbon nanotubes (CNTs) in polymeric matrices include CNTs dispersed in a host polymer or copolymer whose monomers have delocalized electron orbitals, so that a dispersion interaction results between the host polymer or copolymer and the CNTs dispersed therein. Nanocomposite products, which are presented in bulk, or when fabricated as a film, fiber, foam, coating, adhesive, paste, or molding, are prepared by standard means from the present stable dispersions of CNTs in polymeric matrices, employing dispersion interactions, as presented hereinabove.

Topography and its effects on atmospheric dispersion in a risk study for nuclear facilities

International Nuclear Information System (INIS)

Wittek, P.

1985-07-01

In the consequence assessment model, applied in the German Reactor Risk Study (GRRS), atmospheric dispersion of radioactive substances is beeing treated with a straight line Gaussian dispersion model. But some of the German nuclear power plants are located in complex terrain. In this report, the 19 sites which are considered in the GRRS, are described and classified by two different methods in respect to terrain complexity. The relevant effects of the terrain on the dispersion are commented. Two modifications of the GRRS consequence assessment code UFOMOD take into account in a simple way the terrain elevation and the enhanced turbulence effected eventually by the terrain structure. Sample calculations for two release categories of the GRRS demonstrate the effect of these modifications on the calculated number of early fatalities. (orig.) [de

Energy-dispersive X-ray diffraction beamline at Indus-2 synchrotron ...

Indian Academy of Sciences (India)

An energy-dispersive X-ray diffraction beamline has been designed, developed and commissioned at BL-11 bending magnet port of the Indian synchrotron source, Indus-2. The performance of this beamline has been benchmarked by measuring diffraction patterns from various elemental metals and standard inorganic ...

The role of wind in hydrochorous mangrove propagule dispersal

Directory of Open Access Journals (Sweden)

T. Van der Stocken

2013-06-01

the floating orientation of the propagules. While the dispersal path of vertically floating propagules was influenced by the strength and direction of the water currents and to a lesser extent by ambient wind conditions, the dispersal path of horizontally floating propagules was influenced by both strength and direction of the water currents and prevailing wind forces. To validate the flume results, propagules of C. tagal and R. mucronata were released during outgoing tide in a tidal creek in Gazi Bay (Kenya, followed by observation of their dispersal distance and direction, while knowing the actual dominant wind direction. In line with the flume results, this study showed that wind plays an important role in the dispersal distance of the propagules. The present study provides important mechanistic insight into the effect of wind on hydrochorous mangrove propagule dispersal, thereby yielding an essential step towards the construction and optimization of (particle-based hydrodynamic dispersal models.

Evaluation of Fibre Lifetime in Optical Ground Wire Transmission Lines

Science.gov (United States)

Grunvalds, R.; Ciekurs, A.; Porins, J.; Supe, A.

2017-06-01

In the research, measurements of polarisation mode dispersion of two OPGWs (optical ground wire transmission lines), in total four fibres, have been carried out, and the expected lifetime of the infrastructure has been assessed on the basis of these measurements. The cables under consideration were installed in 1995 and 2011, respectively. Measurements have shown that polarisation mode dispersion values for cable installed in 1995 are four times higher than that for cable installed in 2011, which could mainly be explained by technological differences in fibre production and lower fibre polarisation mode dispersion requirements in 1995 due to lack of high-speed (over 10 Gbit/s) optical transmission systems. The calculation methodology of non-refusal work and refusal probabilities, using the measured polarisation mode dispersion parameters, is proposed in the paper. Based on reliability calculations, the expected lifetime is then predicted, showing that all measured fibres most likely will be operational within minimum theoretical service life of 25 years accepted by the industry.

Seed dispersal in six species of terrestrial orchids in Biebrza National Park (NE Poland

Directory of Open Access Journals (Sweden)

Emilia Brzosko

2017-09-01

Full Text Available Knowledge about seed dispersal is required to explain problems in ecology, phylogeography, and conservation biology. Even though seed dispersal is a fundamental mechanism to understand problems at different levels of biological organization (individual, population, species, landscape, it remains one of the least recognized processes. Similar to other groups of plants, very little is known regarding patterns and distances of seed dispersal in orchids. Orchid seeds are generally assumed to be widely dispersed by wind because of their small size and low weight. Between 2006 and 2008, we conducted a field study of the distances at which orchid seeds are dispersed, and determined factors affecting dispersal. Investigations included 13 populations of six terrestrial orchid species – Cypripedium calceolus, Cephalanthera rubra, Epipactis helleborine, Goodyera repens, Neottia ovata, and Platanthera bifolia. To evaluate seed dispersal in orchid populations, 8.5-cm Petri dishes (traps with self-adhesive paper were placed along transects, starting from a group of fruiting plants, which were considered to be the dispersal source. Seeds of the investigated orchid species were dispersed over relatively short distances. There were statistically significant negative correlations between seed density and distance from the fruiting plants. Seeds of species with taller fruiting shoots were dispersed farther than those with shorter ones (R = 0.68, p < 0.05. We discuss the causes and consequences of the dispersal patterns of orchid seeds.

Post Blast Nuclear Forensics Of A Radiological Dispersion Device Scene

International Nuclear Information System (INIS)

Sharon, A.; Halevy, I; Sattinger, D; Admon, U; Banaim, P; Yaar, I.; Krantz, L.

2014-01-01

'Green Field' (GF) project conducting in Israel, between the years ’06-‘14, aimed at increasing the preparedness for outdoor terrorism events, where a radioactive (RA) material is dispersed by an explosive charge. Under the project framework a wide experimental program was established and conducted. The experimental plan included set of about 150 detonation tests that were done in order to close some gaps of knowledge mainly relating to the “source term” characterization. Experiments were done using wide range of different source term parameters. Among these are: explosive types, dispersed materials (both, stable simulants and short live radio isotopes), device geometries, ground surfaces, detonation heights and orientation, atmospheric stability situations etc. Field data collection and documentation used some of the “state of the art” detectors, cameras etc. Based on a comprehensive data analysis and complementary simulations, a methodology for post blast forensic using data collected from the close vicinity of the detention point was developed

Assessment of Safety Parameters for Radiological Explosion Based on Gaussian Dispersion Model

Energy Technology Data Exchange (ETDEWEB)

Pandey, Alok [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Yu, Hyungjoon; Kim, Hong Suk [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2014-10-15

These sources if used with explosive (called RDD - radiological dispersion device), can cause dispersion of radioactive material resulting in public exposure and contamination of the environment. Radiological explosion devices are not weapons for the mass destruction like atom bombs, but can cause the death of few persons and contamination of large areas. The reduction of the threat of radiological weapon attack by terrorist groups causing dispersion of radioactive material is one of the priority tasks of the IAEA Nuclear Safety and Security Program.Emergency preparedness is an essential part for reducing and mitigating radiological weapon threat. Preliminary assessment of dispersion study followed by radiological explosion and its quantitative effect will be helpful for the emergency preparedness team for an early response. The effect of the radiological dispersion depends on various factors like radioisotope, its activity, physical form, amount of explosive used and meteorological factors at the time of an explosion. This study aim to determine the area affected by the radiological explosion as pre assessment to provide feedback to emergency management teams for handling and mitigation the situation after an explosion. Most practical scenarios of radiological explosion are considered with conservative approach for the assessment of the area under a threat for emergency handling and management purpose. Radioisotopes under weak security controls can be used for a radiological explosion to create terror and socioeconomic threat for the public. Prior assessment of radiological threats is helpful for emergency management teams to take prompt decision about evacuation of the affected area and other emergency handling actions. Comparable activities of Co-60 source used in radiotherapy and Sr-90 source of disused and orphaned RTGs with two different quantities of TNT were used for the scenario development of radiological explosion. In the Basic Safety Standard (BSS

Assessment of Safety Parameters for Radiological Explosion Based on Gaussian Dispersion Model

International Nuclear Information System (INIS)

Pandey, Alok; Yu, Hyungjoon; Kim, Hong Suk

2014-01-01

These sources if used with explosive (called RDD - radiological dispersion device), can cause dispersion of radioactive material resulting in public exposure and contamination of the environment. Radiological explosion devices are not weapons for the mass destruction like atom bombs, but can cause the death of few persons and contamination of large areas. The reduction of the threat of radiological weapon attack by terrorist groups causing dispersion of radioactive material is one of the priority tasks of the IAEA Nuclear Safety and Security Program.Emergency preparedness is an essential part for reducing and mitigating radiological weapon threat. Preliminary assessment of dispersion study followed by radiological explosion and its quantitative effect will be helpful for the emergency preparedness team for an early response. The effect of the radiological dispersion depends on various factors like radioisotope, its activity, physical form, amount of explosive used and meteorological factors at the time of an explosion. This study aim to determine the area affected by the radiological explosion as pre assessment to provide feedback to emergency management teams for handling and mitigation the situation after an explosion. Most practical scenarios of radiological explosion are considered with conservative approach for the assessment of the area under a threat for emergency handling and management purpose. Radioisotopes under weak security controls can be used for a radiological explosion to create terror and socioeconomic threat for the public. Prior assessment of radiological threats is helpful for emergency management teams to take prompt decision about evacuation of the affected area and other emergency handling actions. Comparable activities of Co-60 source used in radiotherapy and Sr-90 source of disused and orphaned RTGs with two different quantities of TNT were used for the scenario development of radiological explosion. In the Basic Safety Standard (BSS

EDPUFF- a Gaussian dispersion code for consequence analysis

International Nuclear Information System (INIS)

Oza, R.B.; Bapat, V.N.; Nair, R.N.; Hukkoo, R.K.; Krishnamoorthy, T.M.

1995-01-01

EDPUFF- Equi Distance Puff is a Gaussian dispersion code in FORTRAN language to model atmospheric dispersion of instantaneous or continuous point source releases. It is designed to incorporate the effect of changing meteorological conditions and source release rates on the spatial distribution profiles and its consequences. Effects of variation of parameters like puff spacing, puff packing, averaging schemes are discussed and the choice of the best values for minimum errors and minimum computer CPU time are identified. The code calculates the doses to individual receptors as well as average doses for population zones from internal and external routes over the area of interest. Internal dose computations are made for inhalation and ingestion pathways while the doses from external route consists of cloud doses and doses from surface deposited activity. It computes inhalation and ingestion dose (milk route only) for critical group (1 yr old child). In case of population zones it finds out maximum possible doses in a given area along with the average doses discussed above. Report gives the doses from various pathways for unit release of fixed duration. (author). 7 refs., figs., 7 appendixes

Review of specific effects in atmospheric dispersion calculations

International Nuclear Information System (INIS)

Underwood, B.Y.; Cooper, P.J.; Holloway, N.J.; Kaiser, G.D.; Nixon, W.

1985-01-01

This work consists of a series of ten individual review Chapters - written between 1980 and 1983 - together with a summary document linking and overviewing the work. The topics covered are as follows: 'Plume Rise in Nuclear Safety Studies'; 'Dry Deposition'; 'Wet Deposition'; 'Atmospheric Dispersion in Urban Environments'; 'Topographical Effects in Nuclear Safety Studies'; 'Coastal Effects and Transport over Water'; 'Time-Varying Meteorology in Consequence Assessment'; 'Building Effects in Nuclear Safety Studies'; 'Effect of Turning of the Wind with Height on Lateral Dispersion'. Although the reviews are, on the whole, general in approach, emphasis has been given where appropriate to the impact of various phenomena on th assessment of reactor accident consequences. In general the work focusses on the 0-100 km range of distance downwind of the source. The reviews fulfil several functions: they serve as introductions to the subject areas; they outline theoretical and experimental developments; they act as reference documents providing a copious source of references for more detailed investigation of particular points; they raise unresolved technical issues and attempt to indicate principal uncertainties; they point to areas requiring further development. (author)

Classification spectra of Sanduleak and Stephenson emission-line stars

International Nuclear Information System (INIS)

Allen, D.A.

1978-01-01

Low dispersion slit spectra of 89 emission-line stars are described; these stars were originally located and classified by Sanduleak and Stephenson in an objective-prism survey. The new data broadly confirm the classification scheme adopted by Sanduleak and Stephenson. In particular most of the large number of symbiotic stars they classified have been confirmed and others found. Many of these contain strong, broad emission bands in their red spectra. Two new Wolf-Rayet stars, one new planetary nebula and two new bipolar reflection nebulae involving hidden emission-line stars have been found. (author)

Classification spectra of Sanduleak and Stephenson emission-line stars

Energy Technology Data Exchange (ETDEWEB)

Allen, D A [Anglo-Australian Observatory, Epping (Australia)

1978-09-01

Low dispersion slit spectra of 89 emission-line stars are described; these stars were originally located and classified by Sanduleak and Stephenson in an objective-prism survey. The new data broadly confirm the classification scheme adopted by Sanduleak and Stephenson. In particular most of the large number of symbiotic stars they classified have been confirmed and others found. Many of these contain strong, broad emission bands in their red spectra. Two new Wolf-Rayet stars, one new planetary nebula and two new bipolar reflection nebulae involving hidden emission-line stars have been found.

Two-relaxation-time lattice Boltzmann method for the anisotropic dispersive Henry problem

Science.gov (United States)

Servan-Camas, Borja; Tsai, Frank T.-C.

2010-02-01

This study develops a lattice Boltzmann method (LBM) with a two-relaxation-time collision operator (TRT) to cope with anisotropic heterogeneous hydraulic conductivity and anisotropic velocity-dependent hydrodynamic dispersion in the saltwater intrusion problem. The directional-speed-of-sound technique is further developed to address anisotropic hydraulic conductivity and dispersion tensors. Forcing terms are introduced in the LBM to correct numerical errors that arise during the recovery procedure and to describe the sink/source terms in the flow and transport equations. In order to facilitate the LBM implementation, the forcing terms are combined with the equilibrium distribution functions (EDFs) to create pseudo-EDFs. This study performs linear stability analysis and derives LBM stability domains to solve the anisotropic advection-dispersion equation. The stability domains are used to select the time step at which the lattice Boltzmann method provides stable solutions to the numerical examples. The LBM was implemented for the anisotropic dispersive Henry problem with high ratios of longitudinal to transverse dispersivities, and the results compared well to the solutions in the work of Abarca et al. (2007).

Dispersion, Topological Scattering, and Self-Interference in Multiply Connected Robertson-Walker Cosmologies

CERN Document Server

Tomaschitz, R

1994-01-01

We investigate scattering effects in open Robertson-Walker cosmologies whose spacelike slices are multiply connected hyperbolic manifolds. We work out an example in which the 3-space is infinite and has the topology of a solid torus. The world-lines in these cosmologies are unstable, and classical probability densities evolving under the horospherical geodesic flow show dispersion, as do the densities of scalar wave packets. The rate of dispersion depends crucially on the expansion factor, and we calculate the time evolution of their widths. We find that the cosmic expansion can confine dispersion: The diameter of the domain of chaoticity in the 3-manifold provides the natural, time-dependent length unit in an infinite, multiply connected universe. In a toroidal 3-space manifold this diameter is just the length of the limit cycle. On this scale we find that the densities take a finite limit width in the late stage of the expansion. In the early stage classical densities and conformally coupled fields approach...

Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part I: Source term estimation and local-scale atmospheric dispersion in early phase of the accident

International Nuclear Information System (INIS)

Katata, Genki; Ota, Masakazu; Terada, Hiroaki; Chino, Masamichi; Nagai, Haruyasu

2012-01-01

The atmospheric release of 131 I and 137 Cs in the early phase of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident from March 12 to 14, 2011 was estimated by combining environmental data with atmospheric dispersion simulations under the assumption of a unit release rate (1 Bq h −1 ). For the simulation, WSPEEDI-II computer-based nuclear emergency response system was used. Major releases of 131 I (>10 15 Bq h −1 ) were estimated when air dose rates increased in FNPP1 during the afternoon on March 12 after the hydrogen explosion of Unit 1 and late at night on March 14. The high-concentration plumes discharged during these periods flowed to the northwest and south–southwest directions of FNPP1, respectively. These plumes caused a large amount of dry deposition on the ground surface along their routes. Overall, the spatial pattern of 137 Cs and the increases in the air dose rates observed at the monitoring posts around FNPP1 were reproduced by WSPEEDI-II using estimated release rates. The simulation indicated that air dose rates significantly increased in the south–southwest region of FNPP1 by dry deposition of the high-concentration plume discharged from the night of March 14 to the morning of March 15. - Highlights: ► Source term during the Fukushima Dai-ichi Nuclear Power Plant accident was estimated. ► Atmospheric dispersion simulation was carried out for estimation. ► Major releases were estimated in the afternoon on March 12 and the night on March 14. ► Air dose rate increased due to dry deposition during the night of March 14.

Aspects of the dispersion of denser-than-air vapours relevant to gas cloud explosions

International Nuclear Information System (INIS)

Wheatley, C.J.; Webber, D.M.

1985-01-01

The essential aim of the study presented here is to improve upon the understanding and prediction of the atmospheric dispersion of denser-than-air vapours, and thereby reduce the uncertainties in predicting hazards which might arise from the accidental release of a dense, flammable vapour cloud. In the first phase of the study, models for dispersion in the atmosphere of denser-than-air vapours are reviewed. It is found that a significant source of uncertainty in predictions of all models is the calculation of dilution caused by turbulence. This is due to spreading and stratification caused by the excess density of the cloud and to the interaction of the cloud motion with the ambient flow field. These effects lead to a complex field of turbulence. An additional, significant source of uncertainty is found to be present in '3D' models due to the use of coarse computational grids. A number of experimental tests are proposed which permit fundamental discrimination between the models with the object of reducing uncertainties. In the second phase of the study, a new 'box' model is proposed (A 'box' model is one in which only gross properties of the flow are predicted). All sources of turbulence are included in a way consistent with laboratory studies of entrainment in stratified flows. The prescribed concentration distribution models the initial 'mixed layer'/'gravity spreading' phase and the final 'passive' phase of dispersion with a smooth transition between the two. In the third phase of the study, implications of dispersion of denser-than-air flammable vapour clouds in open terrain for flame speeds following ignition by a weak source are assessed. It is concluded that flame speeds sufficient to cause significant overpressures cannot occur in unobstructed terrain. (author)

Hybrid dispersive media with controllable wave propagation: A new take on smart materials

Energy Technology Data Exchange (ETDEWEB)

Bergamini, Andrea E., E-mail: andrea.bergamini@empa.ch [Empa, Materials Science and Technology, Laboratory for Mechanical Integrity of Energy Systems, Überlandstrasse 129, CH-8600, Dübendorf (Switzerland); Zündel, Manuel [ETH Zürich, Institute of Mechanical Systems, Leonhardstrasse 21, CH-8092 Zürich (Switzerland); Flores Parra, Edgar A.; Ermanni, Paolo [ETH Zürich, Composite Materials and Adaptive Structures Laboratory, Leonhardstrasse 21, CH-8092 Zürich (Switzerland); Delpero, Tommaso [Empa, Materials Science and Technology, Laboratory for Mechanical Integrity of Energy Systems, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Ruzzene, Massimo [Georgia Institute of Technology, G.W. Woodruff School of Mechanical Engineering, 801 Ferst Drive, Atlanta, Georgia 30332-0405 (United States)

2015-10-21

In this paper, we report on the wave transmission characteristics of a hybrid one dimensional (1D) medium. The hybrid characteristic is the result of the coupling between a 1D mechanical waveguide in the form of an elastic beam, supporting the propagation of transverse waves and a discrete electrical transmission line, consisting of a series of inductors connected to ground through capacitors. The capacitors correspond to a periodic array of piezoelectric patches that are bonded to the beam and that couple the two waveguides. The coupling leads to a hybrid medium that is characterized by a coincidence condition for the frequency/wavenumber value corresponding to the intersection of the branches of the two waveguides. In the frequency range centered at coincidence, the hybrid medium features strong attenuation of wave motion as a result of the energy transfer towards the electrical transmission line. This energy transfer, and the ensuing attenuation of wave motion, is alike the one obtained through internal resonating units of the kind commonly used in metamaterials. However, the distinct shape of the dispersion curves suggests how this energy transfer is not the result of a resonance and is therefore fundamentally different. This paper presents the numerical investigation of the wave propagation in the considered media, it illustrates experimental evidence of wave transmission characteristics and compares the performance of the considered configuration with that of internal resonating metamaterials. In addition, the ability to conveniently tune the dispersion properties of the electrical transmission line is exploited to adapt the periodicity of the domain and to investigate diatomic periodic configurations that are characterized by a richer dispersion spectrum and broader bandwidth of wave attenuation at coincidence. The medium consisting of mechanical, piezoelectric, and analog electronic elements can be easily interfaced to digital devices to offer a novel

Dispersion-convolution model for simulating peaks in a flow injection system.

Science.gov (United States)

Pai, Su-Cheng; Lai, Yee-Hwong; Chiao, Ling-Yun; Yu, Tiing

2007-01-12

A dispersion-convolution model is proposed for simulating peak shapes in a single-line flow injection system. It is based on the assumption that an injected sample plug is expanded due to a "bulk" dispersion mechanism along the length coordinate, and that after traveling over a distance or a period of time, the sample zone will develop into a Gaussian-like distribution. This spatial pattern is further transformed to a temporal coordinate by a convolution process, and finally a temporal peak image is generated. The feasibility of the proposed model has been examined by experiments with various coil lengths, sample sizes and pumping rates. An empirical dispersion coefficient (D*) can be estimated by using the observed peak position, height and area (tp*, h* and At*) from a recorder. An empirical temporal shift (Phi*) can be further approximated by Phi*=D*/u2, which becomes an important parameter in the restoration of experimental peaks. Also, the dispersion coefficient can be expressed as a second-order polynomial function of the pumping rate Q, for which D*(Q)=delta0+delta1Q+delta2Q2. The optimal dispersion occurs at a pumping rate of Qopt=sqrt[delta0/delta2]. This explains the interesting "Nike-swoosh" relationship between the peak height and pumping rate. The excellent coherence of theoretical and experimental peak shapes confirms that the temporal distortion effect is the dominating reason to explain the peak asymmetry in flow injection analysis.

Does nanoparticles dispersed in a phase change material improve melting characteristics?

NARCIS (Netherlands)

Farsani, Rouhollah Yadollahi; Raisi, Afrasiab; Nadooshan, Afshin Ahmadi; Vanapalli, Srinivas

2017-01-01

Nanoparticles dispersed in a phase change material alter the thermo-physical properties of the base material, such as thermal conductivity, viscosity, and specific heat capacity. These properties combined with the configuration of the cavity, and the location of the heat source, influence the

Underwater tracking of a moving dipole source using an artificial lateral line: algorithm and experimental validation with ionic polymer–metal composite flow sensors

International Nuclear Information System (INIS)

Abdulsadda, Ahmad T; Tan, Xiaobo

2013-01-01

Motivated by the lateral line system of fish, arrays of flow sensors have been proposed as a new sensing modality for underwater robots. Existing studies on such artificial lateral lines (ALLs) have been mostly focused on the localization of a fixed underwater vibrating sphere (dipole source). In this paper we examine the problem of tracking a moving dipole source using an ALL system. Based on an analytical model for the moving dipole-generated flow field, we formulate a nonlinear estimation problem that aims to minimize the error between the measured and model-predicted magnitudes of flow velocities at the sensor sites, which is subsequently solved with the Gauss–Newton scheme. A sliding discrete Fourier transform (SDFT) algorithm is proposed to efficiently compute the evolving signal magnitudes based on the flow velocity measurements. Simulation indicates that it is adequate and more computationally efficient to use only the signal magnitudes corresponding to the dipole vibration frequency. Finally, experiments conducted with an artificial lateral line consisting of six ionic polymer–metal composite (IPMC) flow sensors demonstrate that the proposed scheme is able to simultaneously locate the moving dipole and estimate its vibration amplitude and traveling speed with small errors. (paper)

Wood pole overhead lines

CERN Document Server

Wareing, Brian

2005-01-01

This new book concentrates on the mechanical aspects of distribution wood pole lines, including live line working, environmental influences, climate change and international standards. Other topics include statutory requirements, safety, profiling, traditional and probabilistic design, weather loads, bare and covered conductors, different types of overhead systems, conductor choice, construction and maintenance. A section has also been devoted to the topic of lightning, which is one of the major sources of faults on overhead lines. The book focuses on the effects of this problem and the strate

Possible applications of energy-dispersive powder diffractometry in the phase analysis of metallurgical and geological specimens

International Nuclear Information System (INIS)

Koch, S.; Jugelt, P.

1978-01-01

Energy-dispersive powder diffractometry renders possible nondestructive quantitative determination of both α and γ phases of iron with shorter measuring time as compared to angle-dispersive techniques. In investigating geological specimens above all the possibility of obtaining qualitative survey analyses within short time is advantageous. The comparatively lower separability leads to difficulties because of increased line density. Therefore, quantitative phase analysis requires the use of spectra unfolding programmes. For laboratory analyses it is advantageous that the same measuring equipment allows the performance of multi-element analyses. (author)

New method of interpretation of the solar spectrum lines

International Nuclear Information System (INIS)

Sitnik, G.F.

1975-01-01

Close triplet lines, which appear from a common low level or from low sublevels with small energy difference are used. It is supposed that for such lines both the function of the source in line and the frequency dependence of the selective coefficient of absorption are the same over any depth of the region of line production in the atmosphere and change with the depth equally. The residual intensities of some lines of the triplet, which are measured for every line at a number of profile points (at the same distance from its center and at different distances from the solar limb center), serve as initial material. The intensities are expressed in terms of the intensity of the continuous spectrum in the center of the solar limb for the average wave length of the triplet interval. Such observations avoid the usual assumption about the source function constancy in line inside the line. On the contrary, the frequency dependence of this function is clarified by the use of this method. Calculations make it possible to determine the source function in line and its long-wave dependence inside the line; to derive a solar atmosphere model and to determine the source function in the continuous spectrum in accordance with observations at profile points in its middle part and in the wing; to find the relation between the selective and continuous absorption coefficients in the dependence on the optical depth in the continuous spectrum; and to find the long-wave dependences of coefficients for both the selective absorption and the selective emission at different optical depths