WorldWideScience

Sample records for near-field environment geochemistry

  1. Development of the near field geochemistry model

    International Nuclear Information System (INIS)

    Arcos, D.; Bruno, J.; Duro, L.; Grive, M.

    2000-01-01

    This report discusses in a quantitative manner the evolution of the near field geochemistry as a result of the interactions between two different introducing granitic groundwaters and the FEBEX bentonite as a buffer material. The two granitic groundwaters considered are: SR-5 water, sampled in a borehole at 500 m depth in Mina Ratones, and a mean composition of different granitic groundwaters from the iberian Massif. The steel canister has also been introduced by considering the iron corrosion in anoxic conditions. (Author)

  2. Microbial Impacts to the Near-Field Environment Geochemistry (MING): A Model for Estimating Microbial Communities in Repository Drifts at Yucca Mountain

    International Nuclear Information System (INIS)

    Jolley, D.M.; Ehrhorn, T.F.; Horn, J.

    2002-01-01

    Geochemical and microbiological modeling was performed to evaluate the potential quantities and impact of microorganisms on the geochemistry of the area adjacent to and within nuclear waste packages in the proposed repository drifts at Yucca Mountain, Nevada. The microbial growth results from the introduction of water, ground support, and waste package materials into the deep unsaturated rock. The simulations, which spanned one million years, were accomplished using a newly developed computer code, Microbial Impacts to the Near-Field Environment Geochemistry (MING). MING uses environmental thresholds for limiting microbial growth to temperatures below 120 C and above relative humidities of 90 percent in repository drifts. Once these thresholds are met, MING expands upon a mass balance and thermodynamic approach proposed by McKinley and others (1997), by using kinetic rates to supply constituents from design materials and constituent fluxes including solubilized rock components into the drift, to perform two separate mass-balance calculations as a function of time. The first (nutrient limit) assesses the available nutrients (C, N, P and S) and calculates how many microorganisms can be produced based on a microorganism stoichiometry of C 160 (H 280 O 80 )N 30 P 2 S. The second (energy limit) calculates the energy available from optimally combined redox couples for the temperature, and pH at that time. This optimization maximizes those reactions that produce > 15kJ/mol (limit on useable energy) using an iterative linear optimization technique. The final available energy value is converted to microbial mass at a rate of 1 kg of biomass (dry weight) for every 64 MJ of energy. These two values (nutrient limit and energy limit) are then compared and the smaller value represents the number of microorganisms that can be produced over a specified time. MING can also be adapted to investigate other problems of interest as the model can be used in saturated and unsaturated

  3. Development of the near field geochemistry model; Desarrollo de un modelo geoquimico de campo proximo

    Energy Technology Data Exchange (ETDEWEB)

    Arcos, D.; Bruno, J.; Duro, L.; Grive, M.

    2000-07-01

    This report discusses in a quantitative manner the evolution of the near field geochemistry as a result of the interactions between two different introducing granitic groundwaters and the FEBEX bentonite as a buffer material. The two granitic groundwaters considered are: SR-5 water, sampled in a borehole at 500 m depth in Mina Ratones, and a mean composition of different granitic groundwaters from the iberian Massif. The steel canister has also been introduced by considering the iron corrosion in anoxic conditions. (Author)

  4. Microbial Impacts to the Near-Field Environment Geochemistry (MING): A Model for Estimating Microbial Communities in Repository Drifts at Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Jolley; T.F. Ehrhorn; J. Horn

    2002-03-19

    Geochemical and microbiological modeling was performed to evaluate the potential quantities and impact of microorganisms on the geochemistry of the area adjacent to and within nuclear waste packages in the proposed repository drifts at Yucca Mountain, Nevada. The microbial growth results from the introduction of water, ground support, and waste package materials into the deep unsaturated rock. The simulations, which spanned one million years, were accomplished using a newly developed computer code, Microbial Impacts to the Near-Field Environment Geochemistry (MING). MING uses environmental thresholds for limiting microbial growth to temperatures below 120 C and above relative humidities of 90 percent in repository drifts. Once these thresholds are met, MING expands upon a mass balance and thermodynamic approach proposed by McKinley and others (1997), by using kinetic rates to supply constituents from design materials and constituent fluxes including solubilized rock components into the drift, to perform two separate mass-balance calculations as a function of time. The first (nutrient limit) assesses the available nutrients (C, N, P and S) and calculates how many microorganisms can be produced based on a microorganism stoichiometry of C{sub 160}(H{sub 280}O{sub 80})N{sub 30}P{sub 2}S. The second (energy limit) calculates the energy available from optimally combined redox couples for the temperature, and pH at that time. This optimization maximizes those reactions that produce > 15kJ/mol (limit on useable energy) using an iterative linear optimization technique. The final available energy value is converted to microbial mass at a rate of 1 kg of biomass (dry weight) for every 64 MJ of energy. These two values (nutrient limit and energy limit) are then compared and the smaller value represents the number of microorganisms that can be produced over a specified time. MING can also be adapted to investigate other problems of interest as the model can be used in saturated

  5. The geochemistry of the near-field

    International Nuclear Information System (INIS)

    McKinley, I.G.

    1985-10-01

    This report describes a study of the Swiss disposal concept used in 'Project Gewaehr 1985' safety analysis. The main components of the near-field of a high level waste repository are the waste glass matrix, the thick steel canister and the surrounding backfill of compressed bentonite. In this report it is concluded that mineralogical alteration of the backfill will be negligibly small over the million year period considered. Its physical and chemical properties can thus be relied on for such a period. The canister will retain its integrity for > 10/sup 3/ y and thereafter will act as an Eh/pH buffer. The near-field buffers ensure more alkaline and reducing conditions than in the far-field. Complete degradation of the glass matrix will take > 10/sup 5/ years and nuclide release will be limited by their congruent dissolution although it may be further constrained by low solubility. Diffusion of dissolved nuclides through the backfill is so slow that many species decay to insignificance within it. The large uptake capacity of the bentonite also significantly extends the release duration for longer lived, non-solubility limited nuclides thus decreasing output mixima. Possible perturbing factors such as radiolysis and hydrogen production by anoxic corrosion are of little importance but modelling of speciation/solubility in the near-field and, in particular, colloid formation and mobility are identified as areas in which more work is required. Although the main analysis aims to err on the side of conservatism, the extent of such pessimism is assessed in a 'realistic' appraisal of the near-field. This suggests that the engineered barriers will prevent any radiologically significant releases over periods in excess of a million years which would strengthen their role in the multiple barrier safety concept. (author)

  6. Near Field Environment Process Model Report

    Energy Technology Data Exchange (ETDEWEB)

    R.A. Wagner

    2000-11-14

    Waste emplacement and activities associated with construction of a repository system potentially will change environmental conditions within the repository system. These environmental changes principally result from heat generated by the decay of the radioactive waste, which elevates temperatures within the repository system. Elevated temperatures affect distribution of water, increase kinetic rates of geochemical processes, and cause stresses to change in magnitude and orientation from the stresses resulting from the overlying rock and from underground construction activities. The recognition of this evolving environment has been reflected in activities, studies and discussions generally associated with what has been termed the Near-Field Environment (NFE). The NFE interacts directly with waste packages and engineered barriers as well as potentially changing the fluid composition and flow conditions within the mountain. As such, the NFE defines the environment for assessing the performance of a potential Monitored Geologic Repository at Yucca Mountain, Nevada. The NFe evolves over time, and therefore is not amenable to direct characterization or measurement in the ambient system. Analysis or assessment of the NFE must rely upon projections based on tests and models that encompass the long-term processes of the evolution of this environment. This NFE Process Model Report (PMR) describes the analyses and modeling based on current understanding of the evolution of the near-field within the rock mass extending outward from the drift wall.

  7. Urban environmental geochemistry of trace metals

    International Nuclear Information System (INIS)

    Wong, Coby S.C.; Li Xiangdong; Thornton, Iain

    2006-01-01

    As the world's urban population continues to grow, it becomes increasingly imperative to understand the dynamic interactions between human activities and the urban environment. The development of urban environmental geochemistry has yielded a significant volume of scientific information about geochemical phenomena found uniquely in the urban environment, such as the distribution, dispersion, and geochemical characteristics of some toxic and potentially toxic trace metals. The aim of this paper is to provide an overview of the development of urban environmental geochemistry as a field of scientific study and highlight major transitions during the course of its development from its establishment to the major scientific interests in the field today. An extensive literature review is also conducted of trace metal contamination of the urban terrestrial environment, in particular of urban soils, in which the uniqueness of the urban environment and its influences on trace metal contamination are elaborated. Potential areas of future development in urban environmental geochemistry are identified and discussed. - Urban environmental geochemistry as a scientific discipline provides valuable information on trace metal contamination of the urban environment and its associated health effects

  8. The genetics of geochemistry

    OpenAIRE

    Croal, Laura R.; Gralnick, Jeffrey A.; Malasarn, Davin; Newman, Dianne K.

    2004-01-01

    Bacteria are remarkable in their metabolic diversity due to their ability to harvest energy from myriad oxidation and reduction reactions. In some cases, their metabolisms involve redox transformations of metal(loid)s, which lead to the precipitation, transformation, or dissolution of minerals. Microorganism/mineral interactions not only affect the geochemistry of modern environments, but may also have contributed to shaping the near-surface environment of the early Earth. For example, bacter...

  9. Problems of applied geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikov, L N

    1983-01-01

    The concept of applied geochemistry was introduced for the first time by A. Ye. Fersman. He linked the branched and complicated questions of geochemistry with specific problems of developing the mineral and raw material base of our country. Geochemical prospecting and geochemistry of mineral raw materials are the most important sections of applied geochemistry. This now allows us the right to view applied geochemistry as a sector of science which applies geochemical methodology, set of geochemical methods of analysis, synthesis, geological interpretation of data based on laws governing theoretical geochemistry to the solution of different tasks of geology, petrology, tectonics, stratigraphy, science of minerals and other geological sciences, and also the technology of mineral raw materials, interrelationships of man and nature (ecogeochemistry, technogeochemistry, agrogeochemistry). The main problem of applied geochemistry, geochemistry of ore fields is the prehistory of ore formation. This is especially important for metallogenic and forecasting constructions, for an understanding of the reasons for the development of fields and the detection of laws governing their distribution, their genetic links with the general geological processes and the products of these processes.

  10. Energy-based method for near-real time modeling of sound field in complex urban environments.

    Science.gov (United States)

    Pasareanu, Stephanie M; Remillieux, Marcel C; Burdisso, Ricardo A

    2012-12-01

    Prediction of the sound field in large urban environments has been limited thus far by the heavy computational requirements of conventional numerical methods such as boundary element (BE) or finite-difference time-domain (FDTD) methods. Recently, a considerable amount of work has been devoted to developing energy-based methods for this application, and results have shown the potential to compete with conventional methods. However, these developments have been limited to two-dimensional (2-D) studies (along street axes), and no real description of the phenomena at issue has been exposed. Here the mathematical theory of diffusion is used to predict the sound field in 3-D complex urban environments. A 3-D diffusion equation is implemented by means of a simple finite-difference scheme and applied to two different types of urban configurations. This modeling approach is validated against FDTD and geometrical acoustic (GA) solutions, showing a good overall agreement. The role played by diffraction near buildings edges close to the source is discussed, and suggestions are made on the possibility to predict accurately the sound field in complex urban environments, in near real time simulations.

  11. Global water cycle: geochemistry and environment

    National Research Council Canada - National Science Library

    Berner, Elizabeth Kay; Berner, Robert A

    1987-01-01

    .... The book provides an integrated approach to global geochemistry and environmental problems and introduces the reader to some fundamental concepts of geology, oceanography, meteorology, environmental...

  12. Contaminant geochemistry. Interactions and transport in the subsurface environment

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, Brian; Dror, Ishai; Yaron, Bruno [Weizmann Institute of Science, Rehovot (Israel). Dept. of Environmental Sciences and Energy Research

    2008-07-01

    This book combines earth science, subsurface hydrology and environmental geochemistry, providing a comprehensive background for specialists interested in the protection and sustainable management of the subsurface environment. The reader is introduced to the chemistry of contaminants, which usually disturb the natural equilibrium in the subsurface as a result of human activity. The major focus of the book is on contaminant reactions in soil solutions, groundwater and porous media solid phases, accounting for their persistence and transformation in the subsurface, as they are transported from the land surface into groundwater. Discussions on selected case studies are provided. (orig.)

  13. Analysis of near-field thermal and psychometric waste package environment using ventilation

    International Nuclear Information System (INIS)

    Danko, G.

    1995-03-01

    The ultimate objective of the Civilian Radioactive Waste Management System (CRWMS) Program is to safely emplace and isolate the nations' spent nuclear fuel (SNF) and radioactive wastes in a geologic repository. Radioactive waste emplaced in a geologic repository will generate heat, increasing the temperature in the repository. The magnitude of this temperature increase depends upon (1) the heat source, i.e. the thermal loading of the repository, and (2) the geologic and engineered heat transport characteristics of the repository. Thermal management techniques currently under investigation include ventilation of the emplacement drifts during the preclosure period which could last as long as 100 years. Understanding the amount of heat and moisture removed from the emplacement drifts and near-field rock by ventilation, are important in determining performance of the engineered barrier system (EBS), as well as the corrosive environment of the waste packages, and the interaction of the EBS with the near-field host rock. Since radionuclide releases and repository system performance are significantly affected by the corrosion rate related to the psychometric environment, it is necessary to predict the amount of heat and moisture that are removed from the repository horizon using a realistic model for a wide range of thermal loading. This can be realized by coupling the hydrothermal model of the rock mass to a ventilation/climate model which includes the heat and moisture transport on the rock-air interface and the dilution of water vapor in the drift. This paper deals with the development of the coupled model concept, and determination of the boundary conditions for the calculations

  14. Long-term behaviour of waste-forms in the near-field environment of a deep underground storage site, overview

    International Nuclear Information System (INIS)

    Toulhoat, P.; Lassabatere, Th.; Galle, Ch.; Cranga, M.; Trotignon, L.; Maillard, S.; Iracane, D.

    1997-01-01

    CEA (French Atomic Energy Commission) is responsible for the achievement of high activity and/or long life waste conditioning processes. Various waste-forms are used (glass, bitumen, etc...). ANDRA (French National Agency for Nuclear Waste Management) has to integrate the long-term durability of such waste-forms in the conception of a deep disposal and the assessment of its long-term confinement performances. The influence of near-field and of the boundary conditions imposed by the far-field on the long-term evolution is being more and more documented. Transport properties and reactivity of silica in the near field is one of the best examples of such effects. A coherent framework with relevant successive events (site re-saturation, chemical evolution of the engineered barrier, overpack corrosion) and a thorough analysis of hierarchized couplings are necessary to evaluate the long term durability of waste-form, and finally, to deliver a near-field-integrated source-term of radionuclides versus lime. We present hereafter some preliminary results obtained in the framework of the CEA 'C3P' project - long-term behaviour of waste-forms in their near-field environment. (authors)

  15. Geochemistry of subduction zone serpentinites: A review

    OpenAIRE

    DESCHAMPS, Fabien; GODARD, Marguerite; GUILLOT, Stéphane; HATTORI, Kéiko

    2013-01-01

    Over the last decades, numerous studies have emphasized the role of serpentinites in the subduction zone geodynamics. Their presence and role in subduction environments are recognized through geophysical, geochemical and field observations of modern and ancient subduction zones and large amounts of geochemical database of serpentinites have been created. Here, we present a review of the geochemistry of serpentinites, based on the compilation of ~ 900 geochemical data of abyssal, mantle wedge ...

  16. Near-field geologic environment as an effective barrier against radionuclide transport

    International Nuclear Information System (INIS)

    Umeki, H.; Sakuma, H.; Ishiguro, K.; Hatanaka, K.; Naito, M.

    1993-01-01

    A generic performance assessment of the geologic disposal system of HLW in Japan has been carried out by the Power Reactor and Nuclear Fuel Development Corporation (PNC) in accordance with the overall HLW management program defined by the Japanese Atomic Energy Commission. A massive engineered barrier system, consisting of vitrified waste, carbon-steel overpack and thick bentonite buffer, is introduced to ensure a long-term performance of the disposal system considering a wide range of geologic environment. A major part of the total performance of the disposal system is borne by the engineered barrier system given a geologic environment that assures and complements the performance of such engineered barrier system. The performance of the natural barrier system coupled with the strong engineered barrier system was investigated by sensitivity analyses. Two types of conceptual model were considered for the analysis to describe radionuclide transport in geologic media and the range of relevant parameters was given by taking the variation of the geologic environment in Japan into account. The results show that the degree of retardation of radionuclide transport chosen in the geologic media varies significantly depending on the parameter values chosen. However, it is indicated that there are realistic combinations of those geologic parameter values which could provide a sufficient degree of retardation within a range of only a few tens of meters from the engineered barrier system. The relative importance of the near-field geologic environment is also discussed

  17. Radiogenic isotope geochemistry of sedimentary and aquatic systems

    International Nuclear Information System (INIS)

    Stille, P.; Shields, G.

    1997-01-01

    The following topics are discussed: Basic principles of isotopic geochemistry; weathering; isotopic geochemistry of river water; isotopic geochemistry in the environment; isotopic composition of seawater past and present (Sr, Nd, Pb, Os, Ce); isotope geochemistry of detrital and authigenic clay minerals in marine sediemnts (Rb-Sr, K-Ar, O); the Sm-N isotope system in detrital and authigenic argillaceous sediments. (SR), provided they are of exceptional interest and focused on a single topic. (orig./SR)

  18. Radiogenic isotope geochemistry of sedimentary and aquatic systems

    Energy Technology Data Exchange (ETDEWEB)

    Stille, P.; Shields, G. [Centre National de la Recherche Scientifique (CNRS), 67 - Strasbourg (France). Centre de Sedimentologie et Geochimie de la Surface

    1997-12-31

    The following topics are discussed: Basic principles of isotopic geochemistry; weathering; isotopic geochemistry of river water; isotopic geochemistry in the environment; isotopic composition of seawater past and present (Sr, Nd, Pb, Os, Ce); isotope geochemistry of detrital and authigenic clay minerals in marine sediemnts (Rb-Sr, K-Ar, O); the Sm-N isotope system in detrital and authigenic argillaceous sediments. (SR), provided they are of exceptional interest and focused on a single topic. (orig./SR)

  19. Proceedings of the national symposium on current trends in geochemistry, exploration and environment: abstract book

    International Nuclear Information System (INIS)

    2015-01-01

    The topics covered in this symposium are solid earth geochemistry and geochemical modeling, precambrian geology, geochemistry and petrogenesis, geochemistry, peterogenisis, sedimentology, chemostratigraphy and paleoclimate, atomic minerals, ferrous/non ferrous minerals, REE minerals, PGE and base metals, oil, hydrocarbons, industrial minerals and gem stones, hydrogeochemistry, environmental geochemistry, biogeochemistry and medical geology and analytical geochemistry and method development. Papers relevant to INIS are indexed separately

  20. Yucca Mountain near-field environment considerations for engineered barrier system design and performance

    International Nuclear Information System (INIS)

    Wilder, D.G.

    1991-05-01

    The United States Department of Energy (DOE) is investigating the suitability of Yucca Mountain (YM) as a potential site for the nation's first High-Level Nuclear Waste Repository. This responsibility includes materials testing and selections, design criteria development, waste form characterizations, performance assessments, and Near-Field (NF) environment characterization. These areas of responsibility are interrelated and to a large extent depend on environmental conditions surrounding the EBS components. The focus of this paper is to discuss what is currently known about the NF environment, particularly those aspects whose interaction with EBS components have significant impacts on the performance of the EBS and its ability to contribute to the isolation of radioactive waste. Reference designs and design/processes assumptions are used to evaluate the expected NF environmental conditions. This report will not focus on providing parameter values but rather on the processes that influence those parameters and on the impacts of those parameters on the performance of EBS components. Where values are given, they should be viewed as typical of YM as a whole but not necessarily representative of the actual NF environment conditions that surround the EBS components. 19 refs., 6 figs

  1. Natural analogue of redox front formation in near-field environment at post-closure phase of HLW geological disposal

    International Nuclear Information System (INIS)

    Yoshida, Hidekazu; Yamamoto, Koushi; Amano, Yuki

    2005-01-01

    Redox fronts are created in the near field of rocks, in a range of oxidation environments, by microbial activity in rock groundwater. Such fronts, and the associated oxide formation, are usually unavoidable around high level radioactive waste (HLW) repositories, whatever their design. The long term behaviour of these oxides after repositories have been closed is however little known. Here we introduce an analogue of redox front formation, such as 'iron oxide' deposits, known as takashikozo forming cylindrical nodules, and the long term behaviour of secondarily formed iron oxyhydroxide in subsequent geological environments. (author)

  2. Field-scale study of the influence of differing remediation strategies on trace metal geochemistry in metal mine tailings from the Irish Midlands.

    Science.gov (United States)

    Perkins, William T; Bird, Graham; Jacobs, Suzanne R; Devoy, Cora

    2016-03-01

    Mine tailings represent a globally significant source of potentially harmful elements (PHEs) to the environment. The management of large volumes of mine tailings represents a major challenge to the mining industry and environmental managers. This field-scale study evaluates the impact of two highly contrasting remediation approaches to the management and stabilisation of mine tailings. The geochemistry of the tailings, overlying amendment layers and vegetation are examined in the light of the different management approaches. Pseudo-total As, Cd and Pb concentrations and solid-state partitioning (speciation), determined via sequential extraction, were established for two Tailings Management Facilities (TMFs) in Ireland subjected to the following: (1) a 'walk-away' approach (Silvermines) and (2) application of an amendment layer (Galmoy). PHE concentrations in roots and herbage of grasses growing on the TMFs were also determined. Results identify very different PHE concentration profiles with depth through the TMFs and the impact of remediation approach on concentrations and their potential bioavailability in the rooting zone of grass species. Data also highlight the importance of choice of grass species in remediation approaches and the benefits of relatively shallow-rooting Agrostis capillaris and Festuca rubra varieties. In addition, data from the Galmoy TMF indicate the importance of regional soil geochemistry for interpreting the influence of the PHE geochemistry of capping and amendment layers applied to mine tailings.

  3. Salton Sea Geothermal Field, California, as a near-field natural analog of a radioactive waste repository in salt

    Science.gov (United States)

    Elders, W. A.; Cohen, L. H.

    1983-11-01

    Since high concentrations of radionuclides and high temperatures are not normally encountered in salt domes or beds, finding an exact geologic analog of expected near-field conditions in a mined nuclear waste repository in salt will be difficult. The Salton Sea Geothermal Field, however, provides an opportunity to investigate the migration and retardation of naturally occurring U, Th, Ra, Cs, Sr and other elements in hot brines which have been moving through clay-rich sedimentary rocks for up to 100,000 years. The more than thirty deep wells drilled in this field to produce steam for electrical generation penetrate sedimentary rocks containing concentrated brines where temperatures reach 3650C at only 2 km depth. The brines are primarily Na, K, Ca chlorides with up to 25% of total dissolved solids; they also contain high conentrations of metals such as Fe, Mn, Li, Zn, and Pb. This report describes the geology, geophysics and geochemistry of this system as a prelude to a study of the mobility of naturally occurring radionuclides and radionuclide analogs within it.

  4. Geochemistry of silicon isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Tiping; Li, Yanhe; Gao, Jianfei; Hu, Bin [Chinese Academy of Geological Science, Beijing (China). Inst. of Mineral Resources; Jiang, Shaoyong [China Univ. of Geosciences, Wuhan (China).

    2018-04-01

    Silicon is one of the most abundant elements in the Earth and silicon isotope geochemistry is important in identifying the silicon source for various geological bodies and in studying the behavior of silicon in different geological processes. This book starts with an introduction on the development of silicon isotope geochemistry. Various analytical methods are described and compared with each other in detail. The mechanisms of silicon isotope fractionation are discussed, and silicon isotope distributions in various extraterrestrial and terrestrial reservoirs are updated. Besides, the applications of silicon isotopes in several important fields are presented.

  5. Radiophysical and geomagnetic effects of rocket burn and launch in the near-the-earth environment

    CERN Document Server

    Chernogor, Leonid F

    2013-01-01

    Radiophysical and Geomagnetic Effects of Rocket Burn and Launch in the Near-the-Earth Environment describes experimental and theoretical studies on the effects of rocket burns and launchings on the near-the-Earth environment and geomagnetic fields. It illuminates the main geophysical and radiophysical effects on the ionosphere and magnetosphere surrounding the Earth that accompany rocket or cosmic apparatus burns and launchings from 1,000 to 10,000 kilometers.The book analyzes the disturbances of plasma and the ambient magnetic and electric fields in the near-Earth environment from rocket burn

  6. The 8th ICGG International Conference on Gas Geochemistry Preface: Fluids and tectonics

    Directory of Open Access Journals (Sweden)

    F. Italiano

    2007-06-01

    Full Text Available The 8th International Conference on Gas Geochemistry provided the opportunity for scientists from different countries to meet each other, exchange ideas on the state of the art in gas geochemistry, and discuss advance in fluid geochemistry. The 8th ICGG meeting focused on three main geologic environments currently interacting with the human life: volcanoes, earthquakes and hydrocarbons. Ninety-four presentations gave participants chance to cover a variety of important research topics on gas geochemistry in geosciences including: gas migration in terrestrial and marine environments, Earth degassing and its relation to seismicity, volcanic eruptions, rare gases and application of isotope techniques, measurement and analytical techniques.

  7. The geology and geochemistry of some epigenetic uranium deposits near the Swakop River, South West Africa

    International Nuclear Information System (INIS)

    Hambleton-Jones, B.B.

    1983-10-01

    This study comprises a geological and geochemical investigation of the uranium deposits in the region near the Swakop River which extends from the Langer Heinrich Mountain in the east to the end of the Tumas River in the west. The general geology of the basement rocks in the Langer Heinrich region only is discussed. The general geology of the younger duricrust formations is discussed. Analytical methods were developed for the separation of thorium, protactinium and uranium from geological materials using various chromatographic procedures. Alpha spectrometry, neutron activation analysis and delayed neutron counting were the main techniques used. The occurrence of uranium in the region of study follows a unique geochemical cycle, and the geochemistry at each stage in the cycle was examined. The first stage in the uranium-geochemical cycle was the basement rocks. The second stage in the geochemical cycle of uranium was the subsurface water. The third stage in the geochemical cycle of uranium concerns its occurrence in the duricrust deposits. Isotopic disequilibrium measurements showed that uranium is still migrating, and that the age of the carnotite precipitation is 30 000 years, based on the open-system model of uranium migration. In the final stage of the geochemical cycle, the geochemistry of uranium in seawater and the diatomaceous muds is discussed. A classification system for the uranium deposits near the Swakop River, based on genetic relationships, is proposed and described in terms of the geochemical cycle of uranium, the mode of transport and mode of deposition. The relationships between the duricrust uranium deposits and the other uranium deposits of South Africa are compared

  8. Geochemistry, Mineralogy and Microbiology of Molybdenum in Mining-Affected Environments

    Directory of Open Access Journals (Sweden)

    Francesca Frascoli

    2018-01-01

    Full Text Available Molybdenum is an essential element for life, with growing production due to a constantly expanding variety of industrial applications. The potentially harmful effects of Mo on the environment, and on human and ecosystem health, require knowledge of Mo behavior in mining-affected environments. Mo is usually present in trace amounts in ore deposits, but mining exploitation can lead to wastes with very high Mo concentrations (up to 4000 mg/kg Mo for tailings, as well as soil, sediments and water contamination in surrounding areas. In mine wastes, molybdenum is liberated from sulfide mineral oxidation and can be sorbed onto secondary Fe(III-minerals surfaces (jarosite, schwertmannite, ferrihydrite at moderately acidic waters, or taken up in secondary minerals such as powellite and wulfenite at neutral to alkaline pH. To date, no Mo-metabolising bacteria have been isolated from mine wastes. However, laboratory and in-situ experiments in other types of contaminated land have suggested that several Mo-reducing and -oxidising bacteria may be involved in the cycling of Mo in and from mine wastes, with good potential for bioremediation. Overall, a general lack of data is highlighted, emphasizing the need for further research on the contamination, geochemistry, bio-availability and microbial cycling of Mo in mining-affected environments to improve environmental management and remediation actions.

  9. V Congress of Spanish Geochemistry

    International Nuclear Information System (INIS)

    1993-01-01

    This proceedings book present the lectures of V Spanish geochemistry Congress. The sessions were: 1.- Materials geochemistry and geologic process. 2.- Geochemistry prospection 3.- Environmental geochemistry 4.- Isotopic geochemistry 5.- Organic geochemistry 6.- Natural materials geochemistry for industry 7.- Hydrogeochemistry 8.- Mathematical models in geochemistry 9.- Analysis methods in geochemistry 10.-Training of geochemistry 11.-Cosmochemistry

  10. Near-field NanoThermoMechanical memory

    International Nuclear Information System (INIS)

    Elzouka, Mahmoud; Ndao, Sidy

    2014-01-01

    In this letter, we introduce the concept of NanoThermoMechanical Memory. Unlike electronic memory, a NanoThermoMechanical memory device uses heat instead of electricity to record, store, and recover data. Memory function is achieved through the coupling of near-field thermal radiation and thermal expansion resulting in negative differential thermal resistance and thermal latching. Here, we demonstrate theoretically via numerical modeling the concept of near-field thermal radiation enabled negative differential thermal resistance that achieves bistable states. Design and implementation of a practical silicon based NanoThermoMechanical memory device are proposed along with a study of its dynamic response under write/read cycles. With more than 50% of the world's energy losses being in the form of heat along with the ever increasing need to develop computer technologies which can operate in harsh environments (e.g., very high temperatures), NanoThermoMechanical memory and logic devices may hold the answer

  11. Exposure to Chemicals in Consumer Products: The Role of the Near-Field Environment

    DEFF Research Database (Denmark)

    Fantke, Peter; Ernstoff, Alexi; Huang, L.

    2016-01-01

    Humans can be exposed to chemicals in consumer products during product use and environmental releases with inhalation, ingestion, and dermal uptake as typical exposure routes. Nevertheless, chemical exposure modeling has traditionally focused on the far-field with near-field indoor models only...... recently gaining attention. Further, models that are mostly emissions-based, may not necessarily be applicable to all types of chemical release from consumer products. To address this gap, we (1) define a framework to simultaneously account for exposure to chemicals in the near- and far-field, (2......) determine chemical product concentrations for various functional use categories, (3) introduce a quantitative metric linking exposure to chemical mass in products, the Product Intake Fraction (PiF), and (4) demonstrate our framework for various consumer product categories. This framework lends itself...

  12. Uranium project. Geochemistry prospection

    International Nuclear Information System (INIS)

    Lambert, J.

    1983-01-01

    Geochemistry studies the distribution of the chemicals elements in the terrestrial crust and its ways to migrate. The terminology used in this report is the following one: 1) Principles of the prospection geochemistry 2) Stages of the prospection geochemistry 3)utility of the prospection geochemistry 4) geochemistry of uranium 5) procedures used within the framework of uranium project 6) Average available 7) Selection of the zones of prospection geochemistry 8) Stages of the prospection, Sample preparation and analisis 9) Presentation of the results

  13. Expected very-near-field thermal environments for advanced spent-fuel and defense high-level waste packages

    International Nuclear Information System (INIS)

    Rickertsen, L.D.; Misplon, M.A.; Claiborne, H.C.

    1982-03-01

    The very-near-field thermal environments expected in a nuclear waste repository in a salt formation have been evaluated for the Westinghouse Form I advanced waste package concepts. The repository descriptions used to supplement the waste package designs in these analyses are realistic and take into account design constraints to assure conservatism. As a result, areal loadings are well below the acceptable values established for salt repositories. Predicted temperatures are generally well below any temperature limits which have been discussed for waste packages in a salt formation. These low temperatures result from the conservative repository designs. Investigations are also made of the sensitivity of these temperatures to areal loading, canister separation, and other design features

  14. Salton Sea Geothermal Field, California, as a near-field natural analog of a radioactive waste repository in salt

    International Nuclear Information System (INIS)

    Elders, W.A.; Cohen, L.H.

    1983-11-01

    Since high concentrations of radionuclides and high temperatures are not normally encountered in salt domes or beds, finding an exact geologic analog of expected near-field conditions in a mined nuclear waste repository in salt will be difficult. The Salton Sea Geothermal Field, however, provides an opportunity to investigate the migration and retardation of naturally occurring U, Th, Ra, Cs, Sr and other elements in hot brines which have been moving through clay-rich sedimentary rocks for up to 100,000 years. The more than thirty deep wells drilled in this field to produce steam for electrical generation penetrate sedimentary rocks containing concentrated brines where temperatures reach 365 0 C at only 2 km depth. The brines are primarily Na, K, Ca chlorides with up to 25% of total dissolved solids; they also contain high concentrations of metals such as Fe, Mn, Li, Zn, and Pb. This report describes the geology, geophysics and geochemistry of this system as a prelude to a study of the mobility of naturally occurring radionuclides and radionuclide analogs within it. The aim of this study is to provide data to assist in validating quantitative models of repository behavior and to use in designing and evaluating waste packages and engineered barriers. 128 references, 33 figures, 13 tables

  15. Salton Sea Geothermal Field, California, as a near-field natural analog of a radioactive waste repository in salt

    Energy Technology Data Exchange (ETDEWEB)

    Elders, W.A.; Cohen, L.H.

    1983-11-01

    Since high concentrations of radionuclides and high temperatures are not normally encountered in salt domes or beds, finding an exact geologic analog of expected near-field conditions in a mined nuclear waste repository in salt will be difficult. The Salton Sea Geothermal Field, however, provides an opportunity to investigate the migration and retardation of naturally occurring U, Th, Ra, Cs, Sr and other elements in hot brines which have been moving through clay-rich sedimentary rocks for up to 100,000 years. The more than thirty deep wells drilled in this field to produce steam for electrical generation penetrate sedimentary rocks containing concentrated brines where temperatures reach 365/sup 0/C at only 2 km depth. The brines are primarily Na, K, Ca chlorides with up to 25% of total dissolved solids; they also contain high concentrations of metals such as Fe, Mn, Li, Zn, and Pb. This report describes the geology, geophysics and geochemistry of this system as a prelude to a study of the mobility of naturally occurring radionuclides and radionuclide analogs within it. The aim of this study is to provide data to assist in validating quantitative models of repository behavior and to use in designing and evaluating waste packages and engineered barriers. 128 references, 33 figures, 13 tables.

  16. MESSENGER, MErcury: Surface, Space ENvironment, GEochemistry, and Ranging; A Mission to Orbit and Explore the Planet Mercury

    Science.gov (United States)

    1999-01-01

    MESSENGER is a scientific mission to Mercury. Understanding this extraordinary planet and the forces that have shaped it is fundamental to understanding the processes that have governed the formation, evolution, and dynamics of the terrestrial planets. MESSENGER is a MErcury Surface, Space ENvironment, GEochemistry and Ranging mission to orbit Mercury for one Earth year after completing two flybys of that planet following two flybys of Venus. The necessary flybys return significant new data early in the mission, while the orbital phase, guided by the flyby data, enables a focused scientific investigation of this least-studied terrestrial planet. Answers to key questions about Mercury's high density, crustal composition and structure, volcanic history, core structure, magnetic field generation, polar deposits, exosphere, overall volatile inventory, and magnetosphere are provided by an optimized set of miniaturized space instruments. Our goal is to gain new insight into the formation and evolution of the solar system, including Earth. By traveling to the inner edge of the solar system and exploring a poorly known world, MESSENGER fulfills this quest.

  17. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    International Nuclear Information System (INIS)

    Jarek, R.

    2004-01-01

    The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports

  18. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    International Nuclear Information System (INIS)

    G.H. Nieder-Westermann

    2005-01-01

    The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports

  19. Modeling of Coastal Effluent Transport: an Approach to Linking of Far-field and Near-field Models

    International Nuclear Information System (INIS)

    Yang, Zhaoqing; Khangaonkar, Tarang P.

    2008-01-01

    One of the challenges in effluent transport modeling in coastal tidal environments is the proper calculation of initial dilution in connection with the far-field transport model. In this study, an approach of external linkage of far-field and near-field effluent transport models is presented, and applied to simulate the effluent transport in the Port Angeles Harbor, Washington in the Strait of Juan de Fuca. A near-field plume model was used to calculate the effluent initial dilution and a three-dimensional (3-D) hydrodynamic model was developed to simulate the tidal circulation and far-field effluent transport in the Port Angeles Harbor. In the present study, the hydrodynamic model was driven by tides and surface winds. Observed water surface elevation and velocity data were used to calibrate the model over a period covering the neap-spring tidal cycle. The model was also validated with observed surface drogue trajectory data. The model successfully reproduced the tidal dynamics in the study area and good agreements between model results and observed data were obtained. This study demonstrated that the linkage between the near-field and far-field models in effluent transport modeling can be achieved through iteratively adjusting the model grid sizes such that the far-field modeled dilution ratio and effluent concentration in the effluent discharge model grid cell match the concentration calculated by the near-field plume model

  20. Using Recent Advances in 2D Seismic Technology and Surface Geochemistry to Economically Redevelop a Shallow Shelf Carbonate Reservoir: Vernon Field, Isabella County, M, Class III; ANNUAL

    International Nuclear Information System (INIS)

    Wood, James R.; Bornhorst, T.J.; Chittick, S.D.; Harrison, William B.; Tayjor, W. Quinlan

    2001-01-01

    In this project a consortium consisting of Cronus Exploration (Traverse City, MI), Michigan Technological University (Houghton, MI) and Western Michigan University (Kalamazoo, MI) proposed to develop and execute an economical and environmentally sensitive plan for recovery of hydrocarbons from an abandoned shallow-shelf carbonate field that is typical of many fields in the U.S. Midwest. This is a 5-year project that will use surface geochemistry as a tool to reduce risk in locating and producing hydrocarbons in Class II fields. The project will develop new techniques for measuring hydrocarbon gases in the soil horizon to locate new and bypassed oil in the shallow-shelf carbonate environments typified by the Dundee and Trenton Formations of the Michigan Basin (Fisher et. al., 1988). In Phase I of the project, the consortium proposes to re-develop the Vernon Oil field located in Vernon Twp, Isabella County, Michigan and produce both bypassed hydrocarbons from the original field and to locate and produce extensions of the original field

  1. Near field and altered zone environmental report Volume I: technical bases for EBS design

    Energy Technology Data Exchange (ETDEWEB)

    Wilder, D. G., LLNL

    1997-08-01

    This report presents an updated summary of results for the waste package (WP) and engineered barrier system (EBS) evaluations, including materials testing, waste-form characterization, EBS performance assessments, and near-field environment (NFE) characterization. Materials testing, design criteria and concept development, and waste-form characterization all require an understanding of the environmental conditions that will interact with the WP and EBS. The Near-Field Environment Report (NFER) was identified in the Waste Package Plan (WPP) (Harrison- Giesler, 1991) as the formal means for transmitting and documenting this information.

  2. Near-field flat focusing mirrors

    Science.gov (United States)

    Cheng, Yu-Chieh; Staliunas, Kestutis

    2018-03-01

    This article reviews recent progress towards the design of near-field flat focusing mirrors, focusing/imaging light patterns in reflection. An important feature of such flat focusing mirrors is their transverse invariance, as they do not possess any optical axis. We start with a review of the physical background to the different focusing mechanisms of near- and far-field focusing. These near-field focusing devices like flat lenses and the reviewed near-field focusing mirrors can implement planar focusing devices without any optical axis. In contrast, various types of far-field planar focusing devices, such as high-contrast gratings and metasurfaces, unavoidably break the transverse invariance due to their radially symmetrical structures. The particular realizations of near-field flat focusing mirrors including Bragg-like dielectric mirrors and dielectric subwavelength gratings are the main subjects of the review. The first flat focusing mirror was demonstrated with a chirped mirror and was shown to manage an angular dispersion for beam focusing, similar to the management of chromatic dispersion for pulse compression. Furthermore, the reviewed optimized chirped mirror demonstrated a long near-field focal length, hardly achieved by a flat lens or a planar hyperlens. Two more different configurations of dielectric subwavelength gratings that focus a light beam at normal or oblique incidence are also reviewed. We also summarize and compare focusing performance, limitations, and future perspectives between the reviewed flat focusing mirrors and other planar focusing devices including a flat lens with a negative-index material, a planar hyperlens, a high-contrast grating, and a metasurface.

  3. Trace-element speciation and partitioning in environmental geochemistry and health

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.G.; Gibson, M.J.; Lovell, M.A.

    1983-09-01

    Establishment of the chemical form and associations of trace elements is important in the scientifc and medical fields related to environmental geochemistry and health. Fundamental understanding of trace-element behavior, the realistic formulation of historical perspectives of trace-element contamination, an assessment of environmental transformation processes and a thorough appraisal of environment-related ill health and disease all depend on knowledge of the chemical speciation and partitioning of trace elements. These topics and the development of analytical speciation techniques and procedures are discussed with reference to trace-element studies in the Department of Forensic Medicine and Science, University of Glasgow, on lacustrine sediments and water, the atmosphere, soil and street dirt of an urban environment, and human biological fluids. 206 references, 4 figures.

  4. Proceedings of the 3. Brazilian Congress on Geochemistry; 1. Congress on Geochemistry from Portuguese Language Countries - Abstracts

    International Nuclear Information System (INIS)

    1991-01-01

    This congress presents topics about geochemistry, including litho-geochemistry, environmental geochemistry, hydro-geochemistry and surface geochemistry. Works on geochronology and nuclear methods in rocks and minerals are also described. (C.G.C.)

  5. A unidirectional subwavelength focusing near-field plate

    Energy Technology Data Exchange (ETDEWEB)

    Imani, Mohammadreza F.; Grbic, Anthony [Radiation Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-01-28

    Near-field plates consist of non-periodically patterned surfaces that can overcome the diffraction limit and confine electromagnetic fields to subwavelength dimensions. Previous near-field plates experimentally demonstrated extreme field tailoring capabilities. However, their performance suffered from radiation/reflection in undesired directions, those other than the subwavelength focus. This issue can limit the practical use of near-field plates. In this paper, we address this issue by designing a unidirectional near-field plate that can form a subwavelength focal pattern, while suppressing the field radiated/reflected in other directions. The design and operation of the proposed unidirectional near-field plate are verified through full-wave simulation. The unidirectional near-field plate may find application in high resolution imaging and probing, high density data storage, and wireless power transfer systems. As an example, its utility as a high resolution probe is demonstrated through full-wave electromagnetic simulation.

  6. Near-field and far-field modeling of scattered surface waves. Application to the apertureless scanning near-field optical microscopy

    International Nuclear Information System (INIS)

    Muller, J.; Parent, G.; Fumeron, S.; Jeandel, G.; Lacroix, D.

    2011-01-01

    The detection of surface waves through scanning near-field optical microscopy (SNOM) is a promising technique for thermal measurements at very small scales. Recent studies have shown that electromagnetic waves, in the vicinity of a scattering structure such as an atomic force microscopy (AFM) tip, can be scattered from near to far-field and thus detected. In the present work, a model based on the finite difference time domain (FDTD) method and the near-field to far-field (NFTFF) transformation for electromagnetic waves propagation is presented. This model has been validated by studying the electromagnetic field of a dipole in vacuum and close to a dielectric substrate. Then simulations for a tetrahedral tip close to an interface are presented and discussed.

  7. The application of INAA in a study of environment geochemistry on the Xizang (Tibet) Plateau, China

    International Nuclear Information System (INIS)

    Junliang Tian; Puling Liu; Yaqi Li

    1993-01-01

    INAA as a routine analysis method has been used in a study of environment geochemistry on the Xizang (Tibet) Plateau in China, and 34 elements in soil samples were determined by INAA with both short and long irradiations. Some primary results from the study, including mean element concentrations in Tibetian soil, patterns of element distribution in soils developed from main types of parent materials on the plateau are described. The results confirm the expectation that soil formed in such cold and dry environment on the the plateau retained the main geochemical characteristics of the parent materials. However, the results still imply the possible migration of some elements in different bio-climatic environments during the soil formation. The elements in the top soils, mainly the alkalis and alkaline earths, and also As, Br, etc., were enriched or depleted in varying degrees in proportion to their abundance in the parent materials. (author) 9 refs.; 4 tabs

  8. Signal of microstrip scanning near-field optical microscope in far- and near-field zones.

    Science.gov (United States)

    Morozov, Yevhenii M; Lapchuk, Anatoliy S

    2016-05-01

    An analytical model of interference between an electromagnetic field of fundamental quasi-TM(EH)00-mode and an electromagnetic field of background radiation at the apex of a near-field probe based on an optical plasmon microstrip line (microstrip probe) has been proposed. The condition of the occurrence of electromagnetic energy reverse flux at the apex of the microstrip probe was obtained. It has been shown that the nature of the interference depends on the length of the probe. Numerical simulation of the sample scanning process was conducted in illumination-reflection and illumination-collection modes. Results of numerical simulation have shown that interference affects the scanning signal in both modes. However, in illumination-collection mode (pure near-field mode), the signal shape and its polarity are practically insensible to probe length change; only signal amplitude (contrast) is slightly changed. However, changing the probe length strongly affects the signal amplitude and shape in the illumination-reflection mode (the signal formed in the far-field zone). Thus, we can conclude that even small background radiation can significantly influence the signal in the far-field zone and has practically no influence on a pure near-field signal.

  9. Data requirements for integrated near field models

    International Nuclear Information System (INIS)

    Wilems, R.E.; Pearson, F.J. Jr.; Faust, C.R.; Brecher, A.

    1981-01-01

    The coupled nature of the various processes in the near field require that integrated models be employed to assess long term performance of the waste package and repository. The nature of the integrated near field models being compiled under the SCEPTER program are discussed. The interfaces between these near field models and far field models are described. Finally, near field data requirements are outlined in sufficient detail to indicate overall programmatic guidance for data gathering activities

  10. Towards phonon photonics: scattering-type near-field optical microscopy reveals phonon-enhanced near-field interaction

    International Nuclear Information System (INIS)

    Hillenbrand, Rainer

    2004-01-01

    Diffraction limits the spatial resolution in classical microscopy or the dimensions of optical circuits to about half the illumination wavelength. Scanning near-field microscopy can overcome this limitation by exploiting the evanescent near fields existing close to any illuminated object. We use a scattering-type near-field optical microscope (s-SNOM) that uses the illuminated metal tip of an atomic force microscope (AFM) to act as scattering near-field probe. The presented images are direct evidence that the s-SNOM enables optical imaging at a spatial resolution on a 10 nm scale, independent of the wavelength used (λ=633 nm and 10 μm). Operating the microscope at specific mid-infrared frequencies we found a tip-induced phonon-polariton resonance on flat polar crystals such as SiC and Si 3 N 4 . Being a spectral fingerprint of any polar material such phonon-enhanced near-field interaction has enormous applicability in nondestructive, material-specific infrared microscopy at nanoscale resolution. The potential of s-SNOM to study eigenfields of surface polaritons in nanostructures opens the door to the development of phonon photonics--a proposed infrared nanotechnology that uses localized or propagating surface phonon polaritons for probing, manipulating and guiding infrared light in nanoscale devices, analogous to plasmon photonics

  11. Geochemistry of groundwater in the Beaver and Camas Creek drainage basins, eastern Idaho

    Science.gov (United States)

    Rattray, Gordon W.; Ginsbach, Michael L.

    2014-01-01

    The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, is studying the fate and transport of waste solutes in the eastern Snake River Plain (ESRP) aquifer at the Idaho National Laboratory (INL) in eastern Idaho. This effort requires an understanding of the natural and anthropogenic geochemistry of groundwater at the INL and of the important physical and chemical processes controlling the geochemistry. In this study, the USGS applied geochemical modeling to investigate the geochemistry of groundwater in the Beaver and Camas Creek drainage basins, which provide groundwater recharge to the ESRP aquifer underlying the northeastern part of the INL. Data used in this study include petrology and mineralogy from 2 sediment and 3 rock samples, and water-quality analyses from 4 surface-water and 18 groundwater samples. The mineralogy of the sediment and rock samples was analyzed with X-ray diffraction, and the mineralogy and petrology of the rock samples were examined in thin sections. The water samples were analyzed for field parameters, major ions, silica, nutrients, dissolved organic carbon, trace elements, tritium, and the stable isotope ratios of hydrogen, oxygen, carbon, sulfur, and nitrogen. Groundwater geochemistry was influenced by reactions with rocks of the geologic terranes—carbonate rocks, rhyolite, basalt, evaporite deposits, and sediment comprised of all of these rocks. Agricultural practices near and south of Dubois and application of road anti-icing liquids on U.S. Interstate Highway 15 were likely sources of nitrate, chloride, calcium, and magnesium to groundwater. Groundwater geochemistry was successfully modeled in the alluvial aquifer in Camas Meadows and the ESRP fractured basalt aquifer using the geochemical modeling code PHREEQC. The primary geochemical processes appear to be precipitation or dissolution of calcite and dissolution of silicate minerals. Dissolution of evaporite minerals, associated with Pleistocene Lake

  12. Electric field measurements at near-atmospheric pressure by coherent Raman scattering of laser beams

    International Nuclear Information System (INIS)

    Ito, Tsuyohito; Kobayashi, Kazunobu; Hamaguchi, Satoshi; Mueller, Sarah; Czarnetzki, Uwe

    2010-01-01

    Electric field measurements at near-atmospheric pressure environments based on electric-field induced Raman scattering are applied to repetitively pulsed nanosecond discharges. The results have revealed that the peak electric field near the centre of the gap is almost independent of the applied voltage. Minimum sustainable voltage measurements suggests that, at each discharge pulse, charged particles that remain from the previous pulse serve as discharge seeds and play an important role for generation of uniform glow-like discharges.

  13. Contaminant geochemistry. Interactions and transport in the subsurface environment. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, Brian; Dror, Ishai; Yaron, Bruno [Weizmann Institute of Science, Rehovot (Israel). Dept. of Earth and Planetary Sciences

    2014-07-01

    In this updated and expanded second edition, new literature has been added on contaminant fate in the soil-subsurface environment. In particular, more data on the behavior of inorganic contaminants and on engineered nanomaterials were included, the latter comprising a group of ''emerging contaminants'' that may reach the soil and subsurface zones. New chapters are devoted to a new perspective of contaminant geochemistry, namely irreversible changes in pristine land and subsurface systems following chemical contamination. Two chapters were added on this topic, focusing attention on the impact of chemical contaminants on the matrix and properties of both liquid and solid phases of soil and subsurface domains. Contaminant impacts on irreversible changes occurring in groundwater are discussed and their irreversible changes on the porous medium solid phase are surveyed. In contrast to the geological time scale controlling natural changes of porous media liquid and solid phases, the time scale associated with chemical pollutant induced changes is far shorter and extends over a ''human lifetime scale''.

  14. Marine geochemistry ocean circulation, carbon cycle and climate change

    CERN Document Server

    Roy-Barman, Matthieu

    2016-01-01

    Marine geochemistry uses chemical elements and their isotopes to study how the ocean works. It brings quantitative answers to questions such as: What is the deep ocean mixing rate? How much atmospheric CO2 is pumped by the ocean? How fast are pollutants removed from the ocean? How do ecosystems react to the anthropogenic pressure? The book provides a simple introduction to the concepts (environmental chemistry, isotopes), the methods (field approach, remote sensing, modeling) and the applications (ocean circulation, carbon cycle, climate change) of marine geochemistry with a particular emphasis on isotopic tracers. Marine geochemistry is not an isolated discipline: numerous openings on physical oceanography, marine biology, climatology, geology, pollutions and ecology are proposed and provide a global vision of the ocean. It includes new topics based on ongoing research programs such as GEOTRACES, Global Carbon Project, Tara Ocean. It provides a complete outline for a course in marine geochemistry. To favor a...

  15. Chiral near-fields around chiral dolmen nanostructure

    International Nuclear Information System (INIS)

    Fu, Tong; Wang, Tiankun; Chen, Yuyan; Wang, Yongkai; Qu, Yu; Zhang, Zhongyue

    2017-01-01

    Discriminating the handedness of the chiral molecule is of great importance in the field of pharmacology and biomedicine. Enhancing the chiral near-field is one way to increase the chiral signal of chiral molecules. In this paper, the chiral dolmen nanostructure (CDN) is proposed to enhance the chiral near-field. Numerical results show that the CDN can increase the optical chirality of the near-field by almost two orders of magnitude compared to that of a circularly polarized incident wave. In addition, the optical chirality of the near-field of the bonding mode is enhanced more than that of the antibonding mode. These results provide an effective method for tailoring the chiral near-field for biophotonics sensors. (paper)

  16. 10 CFR 960.4-2-2 - Geochemistry.

    Science.gov (United States)

    2010-01-01

    ... DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Postclosure Guidelines § 960.4-2-2 Geochemistry. (a) Qualifying condition. The present and... peak cumulative releases of radionuclides to the accessible environment by a factor of 10 as compared...

  17. Proceedings from the technical workshop on near-field performance assessment for high-level waste

    International Nuclear Information System (INIS)

    Sellin, P.; Apted, M.; Gago, J.

    1991-12-01

    This report contains the proceedings of 'Technical workshop of near-filed performance assessment for high-level waste' held in Madrid October 15-17, 1990. It includes the invited presentations and summaries of the scientific discussions. The workshop covered several topics: * post-emplacement environment, * benchmarking of computer codes, * glass release, * spent-fuel release, * radionuclide solubility, * near-field transport processes, * coupled processes in the near-field, * integrated assessments, * sensitivity analyses and validation. There was an invited presentation on each topic followed by an extensive discussion. One of the points highlighted in the closing discussion of the workshop was the need for international cooperation in the field of near-field performance assessment. The general opinion was that this was best achieved in smaller groups discussing specific questions. (au) Separate abstracts were prepared for 9 papers in this volume

  18. Near field plasmon and force microscopy

    NARCIS (Netherlands)

    de Hollander, R.B.G.; van Hulst, N.F.; Kooyman, R.P.H.

    1995-01-01

    A scanning plasmon near field optical microscope (SPNM) is presented which combines a conventional far field surface plasmon microscope with a stand-alone atomic force microscope (AFM). Near field plasmon and force images are recorded simultaneously both with a lateral resolution limited by the

  19. Geochemistry of the near surface sediments of the Nares Abyssal Plain

    International Nuclear Information System (INIS)

    Carpenter, M.S.N.; Colley, S.; Elderfield, H.; Kennedy, H.A.; Thomson, J.; Wilson, T.R.S.

    1983-01-01

    The geochemistry of a suite of box and 2m gravity cores from the Nares Abyssal Plain has been characterised by means of pore water analyses, XRF determination of major and trace element concentrations, mineralogy and 230 Thsub(excess) dating. The interstitial fluid environment of those deep-sea clays is mildly reducing, although one site exhibits manganese remobilisation and precipitation. Despite their marked colour differences, there is a similarity in clay mineralogy between the grey silt/clay turbidites and the brown clays found in the area. Sediment accumulation rates of pelagic brown clays range between 0.5 and 1.0 cm/10 3 yr. These pelagic brown clays are metal-rich relative to the grey clays, and a model is used to estimate the hydrogenous metal fluxes on the assumption that they are constant over the Plain. This model gives values of approx. 1300 μg/cm 2 /10 3 yr for Mn, approx. 2600 μg/cm 2 /10 3 yr for Fe and Co, Ni, Cu, V and Zn in the range 6 to 26 μg/cm 2 /10 3 yr. An associated model-derived estimate of the detrital contents of the same elements agrees well with the mean values of the grey clays and of average shale. Metal-poor brown clays and assorted minor lithologies are intermediate in composition between these two end-members. (author)

  20. Geochemistry Review Panel report on the SRP geochemistry program and draft geochemistry summary program plan (May, 1986) and discussion of panel recommendations

    International Nuclear Information System (INIS)

    1986-12-01

    The Geochemistry Review Panel (GRP) was established by the Salt Repository Project Office (SRPO) to help evaluate geochemistry-related issues in the US Department of Energy's nuclear waste repository program. The May 1986 meeting of the GRP reviewed the Salt Repository Program (SRP) geochemistry program developed by the Office of Nuclear Waste Isolation (ONWI). This program is described in the Draft Geochemistry Plan of April 9, 1986. This report documents the GRP's comments and recommendations on this subject and the ONWI responses to the specific points raised by the GRP

  1. Study of Near Field Communication Technology in University Scenarios

    Science.gov (United States)

    Ruiz, Irene Luque; Miraz, Guillermo Matas; Gómez-Nieto, Miguel Ángel

    2009-08-01

    In this paper we present an introduction to the possibilities of NFC (Near Field Communication) technology in the University environment. NFC is the key for the development of interactive systems where "intelligent" objects interact with the user just only by touching the objects with a NFC device. We support that a University environment with active objects dispatching information and services to the users (students and teachers) can introduce an appropriate environment for the fulfillment of the new Educational European directives. Here, we briefly describe some of the possibilities of the NFC technology and we include an example of the use of NFC through a Smart Poster for a scenario where a Department directory is considered.

  2. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    Energy Technology Data Exchange (ETDEWEB)

    R. Jarek

    2004-11-23

    The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports.

  3. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    Energy Technology Data Exchange (ETDEWEB)

    G.H. Nieder-Westermann

    2005-04-07

    The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports.

  4. Novel concepts in near-field optics: from magnetic near-field to optical forces

    Science.gov (United States)

    Yang, Honghua

    Driven by the progress in nanotechnology, imaging and spectroscopy tools with nanometer spatial resolution are needed for in situ material characterizations. Near-field optics provides a unique way to selectively excite and detect elementary electronic and vibrational interactions at the nanometer scale, through interactions of light with matter in the near-field region. This dissertation discusses the development and applications of near-field optical imaging techniques, including plasmonic material characterization, optical spectral nano-imaging and magnetic field detection using scattering-type scanning near-field optical microscopy (s-SNOM), and exploring new modalities of optical spectroscopy based on optical gradient force detection. Firstly, the optical dielectric functions of one of the most common plasmonic materials---silver is measured with ellipsometry, and analyzed with the Drude model over a broad spectral range from visible to mid-infrared. This work was motivated by the conflicting results of previous measurements, and the need for accurate values for a wide range of applications of silver in plasmonics, optical antennas, and metamaterials. This measurement provides a reference for dielectric functions of silver used in metamaterials, plasmonics, and nanophotonics. Secondly, I implemented an infrared s-SNOM instrument for spectroscopic nano-imaging at both room temperature and low temperature. As one of the first cryogenic s-SNOM instruments, the novel design concept and key specifications are discussed. Initial low-temperature and high-temperature performances of the instrument are examined by imaging of optical conductivity of vanadium oxides (VO2 and V2O 3) across their phase transitions. The spectroscopic imaging capability is demonstrated on chemical vibrational resonances of Poly(methyl methacrylate) (PMMA) and other samples. The third part of this dissertation explores imaging of optical magnetic fields. As a proof-of-principle, the magnetic

  5. Characteristics of near-field earthquake ground motion

    International Nuclear Information System (INIS)

    Kim, H. K.; Choi, I. G.; Jeon, Y. S.; Seo, J. M.

    2002-01-01

    The near-field ground motions exhibit special response characteristics that are different from those of ordinary ground motions in the velocity and displacement response. This study first examines the characteristics of near-field ground motion depending on fault directivity and fault normal and parallel component. And the response spectra of the near field ground motion are statistically processed, and are compared with the Regulatory Guide 1.60 spectrum that is present design spectrum of the nuclear power plant. The response spectrum of the near filed ground motions shows large spectral velocity and displacement in the low frequency range. The spectral accelerations of near field ground motion are greatly amplified in the high frequency range for the rock site motions, and in the low frequency range for the soil site motions. As a result, the near field ground motion effects should be considered in the seismic design and seismic safety evaluation of the nuclear power plant structures and equipment

  6. The Near-Earth Space Radiation Environment

    Science.gov (United States)

    Xapsos, Michael

    2008-01-01

    This viewgraph presentation reviews the effects of the Near-Earth space radiation environment on NASA missions. Included in this presentation is a review of The Earth s Trapped Radiation Environment, Solar Particle Events, Galactic Cosmic Rays and Comparison to Accelerator Facilities.

  7. The geomicrobiology of the Harwell and Altnabreac boreholes

    International Nuclear Information System (INIS)

    Christofi, N.; West, J.M.; Robbins, J.E.; McKinley, I.G.

    1983-01-01

    Waste repositories in deep environments are likely to contain autochthonous and allochthonous microbial populations which may influence near and far-field conditions. Studies of boreholes in argillaceous and crystalline formations at research sites in the U.K. have revealed the presence of several types of contaminant microorganisms which could affect the integrity of materials used in repository construction, alter the geochemistry and may encourage the release of radionuclides from the near-field environment. (author)

  8. Preliminary analysis for evolution of redox conditions in the near field

    International Nuclear Information System (INIS)

    Chiba, Tamotsu; Miki, Takahito; Inagaki, Manabu; Sasamoto, Hiroshi; Yui, Mikazu

    1999-06-01

    It is planned that high level radioactive waste is going to be disposed under deep geological environment. It is believed that the chemical condition of deep groundwater is generally anoxic and reducing. However, during construction and operation phase of repository, oxygen will diffuse some distance into the surrounding rock mass, and diffused oxygen may remain in the surrounding rock mass even after repository closure. In such a case, the transitional redox condition around the drift is not preferable in view point of safety assessment for HLW disposal. Hence, it is very important to evaluate evolution of redox conditions in the near field. This report describes results of preliminary analysis for evolution of redox conditions in the near field rock mass and buffer after repository closure based on the model developed by Chiba et al. (1999). The results of preliminary analysis are summarized as follows: The decrease of oxygen in the near field rock mass and buffer are affected by pH of groundwater and surface area of iron-bearing minerals. The decrease of oxygen in the near field rock mass takes place at time scales lower than 500 years in considering the hypothetical reference groundwater pH range for H12 report. It is implicated that the redox conditions in the near field rock mass will recover to reducing conditions. The decrease of oxygen in the buffer takes place at time scales lower several tens years under neutral to weakly alkaline pH values of porewater in the buffer, even if it is assumed that residual oxygen in the near field rock mass after repository closure will diffuse into the buffer. On the other hand, under weakly acid pH values of porewater in the buffer, it may be presumed that oxygen remain in the buffer at time scale more than 500 years. (author)

  9. Near Field Communication: Introduction and Implications

    Science.gov (United States)

    McHugh, Sheli; Yarmey, Kristen

    2012-01-01

    Near field communication is an emerging technology that allows objects, such as mobile phones, computers, tags, or posters, to exchange information wirelessly across a small distance. Though primarily associated with mobile payment, near field communication has many different potential commercial applications, ranging from marketing to nutrition,…

  10. Seawater-sediment interaction at elevated temperatures and pressures: implications for the near field chemical environment

    International Nuclear Information System (INIS)

    Seyfried, W.E. Jr.; Thornton, E.C.; Janecky, D.R.

    1981-01-01

    Results of four experiments are reported which document chemical exchange and mineralogic modification during seawater-sediment interaction at 200 0 to 300 0 C, 500 bars. Sediments used for this study are from MPG-1 (central North Pacific). Experimental conditions (T, P, W/R) were chosen to be reasonably analogous to conditions which will characterize the near field environment; that is a zone within approximately 1 m of the buried waste canister. In general, the major element chemistry of seawater was similarly modified in all experiments. The aqueous concentrations of Ca, Mg, Sr, and SO 4 decreased and SiO 2 /sub (aq)/, Na, K, and ΣCO 2 increased relative to values in seawater prior to reaction with sediments. pH decreased and remained distinctly acid. Con comitantly significant concentrations of heavy metals entered seawater from the sediments during reaction. Dissolution of Mn-rich phases profoundly affected alteration processes. For example, reaction of MnO 2 components of the smectite-rich sediment (Pacific smectite) with seawater created an unusually oxidizing milieu (fO 2 = 10 -7 74 ), and resulted in dissolution of significant quantities of Au from the reaction cell. Although illite-quartz-Fe-chlorite (sediment B)-seawater interaction also created a relatively oxidizing environment, this environment was not capable of oxidizing Au. Thus, in this regard (oxidation potential) sediment mineralogy exerts a strong influence. Mineralogic modification of sediment B at 200 0 and 300 0 C was minor and characterized by partial dissolution of illite and exchange of Fe for Mg in chlorite. In contrast the smectite-rich sediment, which, prior to reaction with seawater contained a poorly crystalline smectite phase, clinoptilolite, and amorphous material, recrystallized totally to a well defined smectite mineral. Anhydrite was abundantly present amongst the alteration products of all experiments

  11. Near field plasmon and force microscopy

    OpenAIRE

    de Hollander, R.B.G.; van Hulst, N.F.; Kooyman, R.P.H.

    1995-01-01

    A scanning plasmon near field optical microscope (SPNM) is presented which combines a conventional far field surface plasmon microscope with a stand-alone atomic force microscope (AFM). Near field plasmon and force images are recorded simultaneously both with a lateral resolution limited by the probe size to about 20 nm. At variance to previous work, utilizing a scanning tunneling microscope (STM) with a metallic tip, a dielectric silicon-nitride tip is used in contact mode. This arrangement ...

  12. Survey and review of near-field performance assessment

    International Nuclear Information System (INIS)

    Apted, M.J.

    1993-01-01

    Chemical reactions control the performance, stability, and rate of degradation of natural and engineered barriers to waste repositories of the near field. Chemical processes are overviewed in this context. Temperature, and associated temperature gradients, are also important parameters in near-field performance assessment. The mechanical conditions of the near-field rock will be perturbed by construction of the underground repository. Mechanical analysis in the near field is further complicated by the introduction of HLW canisters and associated engineered barrier materials. Hydrological processes important to near-field performance include those associated with fluid transport. Considerable discussions and studies have been conducted on the issue of coupling among chemical-thermal-mechanical-hydrological processes; they are overviewed. (R.P.) 2 figs., 2 tabs

  13. Quantitative Near-field Microscopy of Heterogeneous and Correlated Electron Oxides

    Science.gov (United States)

    McLeod, Alexander Swinton

    Scanning near-field optical microscopy (SNOM) is a novel scanning probe microscopy technique capable of circumventing the conventional diffraction limit of light, affording unparalleled optical resolution (down to 10 nanometers) even for radiation in the infrared and terahertz energy regimes, with light wavelengths exceeding 10 micrometers. However, although this technique has been developed and employed for more than a decade to a qualitatively impressive effect, researchers have lacked a practically quantitative grasp of its capabilities, and its application scope has so far remained restricted by implementations limited to ambient atmospheric conditions. The two-fold objective of this dissertation work has been to address both these shortcomings. The first half of the dissertation presents a realistic, semi-analytic, and benchmarked theoretical description of probe-sample near-field interactions that form the basis of SNOM. Owing its name to the efficient nano-focusing of light at a sharp metallic apex, the "lightning rod model" of probe-sample near-field interactions is mathematically developed from a flexible and realistic scattering formalism. Powerful and practical applications are demonstrated through the accurate prediction of spectroscopic near-field optical contrasts, as well as the "inversion" of these spectroscopic contrasts into a quantitative description of material optical properties. Thus enabled, this thesis work proceeds to present quantitative applications of infrared near-field spectroscopy to investigate nano-resolved chemical compositions in a diverse host of samples, including technologically relevant lithium ion battery materials, astrophysical planetary materials, and invaluable returned extraterrestrial samples. The second half of the dissertation presents the design, construction, and demonstration of a sophisticated low-temperature scanning near-field infrared microscope. This instrument operates in an ultra-high vacuum environment

  14. 16. International oil field chemistry symposium

    International Nuclear Information System (INIS)

    2006-03-01

    The symposium deals with topics on well chemicals, petrochemicals, well injection fluids, reservoir describing methods, reservoir exploitation enhancing chemicals, corrosion inhibitors, production methods and chemical aspects of maintenance, multiphase flow and reservoir geochemistry. The environmental effects of the chemicals and preservation of the environment is also focussed on. Some aspects of decommissioning of oil fields are dealt with

  15. Survey and review of near-field performance assessment

    International Nuclear Information System (INIS)

    Apted, M.J.

    1993-01-01

    The aim of this chapter is to describe the performance assessment (PA) context in which near-field models have been developed and applied. An overview is given of a number of PA studies. Although the focus is on near-field models, the overview covers the full context in which the PAs have been performed, including the purpose of the studies and regulatory context. Special emphasis has been given to the scenarios analyzed in the assessments; the scenarios set the framework for model development and application. Another aspect to consider in a study of near-field modeling from the perspective of total PA is the linking between near-field and far-field assessment. (R.P.) 6 tabs

  16. SITE-94. Modelling of near-field chemistry for SITE-94

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, R.; Apted, M. [QuantiSci, Denver, CO (United States)

    1996-12-01

    This report evaluates methods for the incorporation of site data into models simulating the long-term chemical evolution of the near field. The models are based on limiting conditions at equilibrium, or steady state, in three closed systems representing fully saturated bentonite, Fe{sup o} corrosion products of the canister and spent fuel. A l kg reference mass of site groundwater is assumed to equilibrate first with bentonite and then with the canister`s corrosion products. A third closed system representing spent fuel is modeled in terms of spent-fuel dissolution in 1 kg of water evolved from the canister, coupled with steady-state constraints on the rate of oxidant production by {alpha} radiolysis of H{sub 2}O(l). Precipitation of secondary minerals controlling the solubilities of radioelements dissolved from spent fuel is also simulated in this model. Version 7.2 of the EQ3/6 geochemical software package and its supporting composite thermodynamic database, dataO.com.R22, are used to carry out these calculations. It is concluded that chemical models of near-field evolution combined with thermodynamic models of radionuclide speciation-solubility behavior can assist efforts to assimilate site characterization data into the performance assessment process, and to deal with uncertainties that are inherent in both site properties and in concepts of near field chemistry. It is essential, however, that expert judgement and prudence should be exercised such that model results are conservative with respect to acknowledged and documented uncertainties. Most importantly, it must be recognized that it is probably not possible to model with a high-level of accuracy the complex chemical environments and long timescales involved in disposal technologies for nuclear wastes. For performance assessment, however, only bounding values are needed, and modeling approaches such as described in this report are useful for this purpose. Technical peer review and cross-comparisons of near-field

  17. Introduction to geochemistry and its applications. Tome 2. Transfer of elements. Geochemical evolution of exogenous domains

    International Nuclear Information System (INIS)

    Hagemann, R.; Treuil, M.

    1998-01-01

    This second tome of the introduction to geochemistry and its applications is divided into 9 chapters dealing with: the chloro-fluoro-methanes as tracers of the oceanic circulation; the study of radioactive disequilibria and their applications; the submarine hydrothermal activity; geochemistry and diagenesis, example of the Trias and Lias of Ardeche (France); the chemistry of deep waters in granitic environment, application to the underground storage of radioactive wastes; the impact of volcanism on atmosphere chemistry; the role of methane and light hydrocarbons in the atmosphere; the challenges of carbon; and the polar caps as recorders of atmosphere geochemistry and climates. (J.S.)

  18. Near-Field Optical Microscopy of Fractal Structures

    DEFF Research Database (Denmark)

    Coello, Victor; Bozhevolnyi, Sergey I.

    1999-01-01

    Using a photon scanning tunnelling microscope combined with a shear-force feedback system, we image both topographical and near-field optical images (at the wavelengths of 633 and 594 nm) of silver colloid fractals. Near-field optical imaging is calibrated with a standing evanescent wave pattern...

  19. Sampling Criterion for EMC Near Field Measurements

    DEFF Research Database (Denmark)

    Franek, Ondrej; Sørensen, Morten; Ebert, Hans

    2012-01-01

    An alternative, quasi-empirical sampling criterion for EMC near field measurements intended for close coupling investigations is proposed. The criterion is based on maximum error caused by sub-optimal sampling of near fields in the vicinity of an elementary dipole, which is suggested as a worst......-case representative of a signal trace on a typical printed circuit board. It has been found that the sampling density derived in this way is in fact very similar to that given by the antenna near field sampling theorem, if an error less than 1 dB is required. The principal advantage of the proposed formulation is its...

  20. Near-Field, On-Chip Optical Brownian Ratchets.

    Science.gov (United States)

    Wu, Shao-Hua; Huang, Ningfeng; Jaquay, Eric; Povinelli, Michelle L

    2016-08-10

    Nanoparticles in aqueous solution are subject to collisions with solvent molecules, resulting in random, Brownian motion. By breaking the spatiotemporal symmetry of the system, the motion can be rectified. In nature, Brownian ratchets leverage thermal fluctuations to provide directional motion of proteins and enzymes. In man-made systems, Brownian ratchets have been used for nanoparticle sorting and manipulation. Implementations based on optical traps provide a high degree of tunability along with precise spatiotemporal control. Here, we demonstrate an optical Brownian ratchet based on the near-field traps of an asymmetrically patterned photonic crystal. The system yields over 25 times greater trap stiffness than conventional optical tweezers. Our technique opens up new possibilities for particle manipulation in a microfluidic, lab-on-chip environment.

  1. Near field ice detection using infrared based optical imaging technology

    Science.gov (United States)

    Abdel-Moati, Hazem; Morris, Jonathan; Zeng, Yousheng; Corie, Martin Wesley; Yanni, Victor Garas

    2018-02-01

    If not detected and characterized, icebergs can potentially pose a hazard to oil and gas exploration, development and production operations in arctic environments as well as commercial shipping channels. In general, very large bergs are tracked and predicted using models or satellite imagery. Small and medium bergs are detectable using conventional marine radar. As icebergs decay they shed bergy bits and growlers, which are much smaller and more difficult to detect. Their low profile above the water surface, in addition to occasional relatively high seas, makes them invisible to conventional marine radar. Visual inspection is the most common method used to detect bergy bits and growlers, but the effectiveness of visual inspections is reduced by operator fatigue and low light conditions. The potential hazard from bergy bits and growlers is further increased by short detection range (<1 km). As such, there is a need for robust and autonomous near-field detection of such smaller icebergs. This paper presents a review of iceberg detection technology and explores applications for infrared imagers in the field. Preliminary experiments are performed and recommendations are made for future work, including a proposed imager design which would be suited for near field ice detection.

  2. Geochemistry of Coal Ash in the Equatorial Wet Disposal System Environment

    OpenAIRE

    Kolay P. K.; Singh H.

    2013-01-01

    The coal utilization in thermal power plants in Malaysia has increased significantly which produces an enormous amount of coal combustion by-product (CCBP) or coal ash and poses severe disposal problem. As each coal ash is distinct, this study presents the geochemistry of the coal ash, in particular fly ash, produced from the combustion of local coal from Kuching Sarawak, Malaysia. The geochemical composition of the ash showed a high amount of silica, alumina, iron oxides and alkalies which w...

  3. Near-field/far-field array manifold of an acoustic vector-sensor near a reflecting boundary.

    Science.gov (United States)

    Wu, Yue Ivan; Lau, Siu-Kit; Wong, Kainam Thomas

    2016-06-01

    The acoustic vector-sensor (a.k.a. the vector hydrophone) is a practical and versatile sound-measurement device, with applications in-room, open-air, or underwater. It consists of three identical uni-axial velocity-sensors in orthogonal orientations, plus a pressure-sensor-all in spatial collocation. Its far-field array manifold [Nehorai and Paldi (1994). IEEE Trans. Signal Process. 42, 2481-2491; Hawkes and Nehorai (2000). IEEE Trans. Signal Process. 48, 2981-2993] has been introduced into the technical field of signal processing about 2 decades ago, and many direction-finding algorithms have since been developed for this acoustic vector-sensor. The above array manifold is subsequently generalized for outside the far field in Wu, Wong, and Lau [(2010). IEEE Trans. Signal Process. 58, 3946-3951], but only if no reflection-boundary is to lie near the acoustic vector-sensor. As for the near-boundary array manifold for the general case of an emitter in the geometric near field, the far field, or anywhere in between-this paper derives and presents that array manifold in terms of signal-processing mathematics. Also derived here is the corresponding Cramér-Rao bound for azimuth-elevation-distance localization of an incident emitter, with the reflected wave shown to play a critical role on account of its constructive or destructive summation with the line-of-sight wave. The implications on source localization are explored, especially with respect to measurement model mismatch in maximum-likelihood direction finding and with regard to the spatial resolution between coexisting emitters.

  4. Nanomanipulation using near field photonics.

    Science.gov (United States)

    Erickson, David; Serey, Xavier; Chen, Yih-Fan; Mandal, Sudeep

    2011-03-21

    In this article we review the use of near-field photonics for trapping, transport and handling of nanomaterials. While the advantages of traditional optical tweezing are well known at the microscale, direct application of these techniques to the handling of nanoscale materials has proven difficult due to unfavourable scaling of the fundamental physics. Recently a number of research groups have demonstrated how the evanescent fields surrounding photonic structures like photonic waveguides, optical resonators, and plasmonic nanoparticles can be used to greatly enhance optical forces. Here, we introduce some of the most common implementations of these techniques, focusing on those which have relevance to microfluidic or optofluidic applications. Since the field is still relatively nascent, we spend much of the article laying out the fundamental and practical advantages that near field optical manipulation offers over both traditional optical tweezing and other particle handling techniques. In addition we highlight three application areas where these techniques namely could be of interest to the lab-on-a-chip community, namely: single molecule analysis, nanoassembly, and optical chromatography. This journal is © The Royal Society of Chemistry 2011

  5. Scanning near-field infrared microscopy on semiconductor structures

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, Rainer

    2011-01-15

    Near-field optical microscopy has attracted remarkable attention, as it is the only technique that allows the investigation of local optical properties with a resolution far below the diffraction limit. Especially, the scattering-type near-field optical microscopy allows the nondestructive examination of surfaces without restrictions to the applicable wavelengths. However, its usability is limited by the availability of appropriate light sources. In the context of this work, this limit was overcome by the development of a scattering-type near-field microscope that uses a widely tunable free-electron laser as primary light source. In the theoretical part, it is shown that an optical near-field contrast can be expected when materials with different dielectric functions are combined. It is derived that these differences yield different scattering cross-sections for the coupled system of the probe and the sample. Those cross-sections define the strength of the near-field signal that can be measured for different materials. Hence, an optical contrast can be expected, when different scattering cross-sections are probed. This principle also applies to vertically stacked or even buried materials, as shown in this thesis experimentally for two sample systems. In the first example, the different dielectric functions were obtained by locally changing the carrier concentration in silicon by the implantation of boron. It is shown that the concentration of free charge-carriers can be deduced from the near-field contrast between implanted and pure silicon. For this purpose, two different experimental approaches were used, a non-interferometric one by using variable wavelengths and an interferometric one with a fixed wavelength. As those techniques yield complementary information, they can be used to quantitatively determine the effective carrier concentration. Both approaches yield consistent results for the carrier concentration, which excellently agrees with predictions from

  6. Scanning near-field infrared microscopy on semiconductor structures

    International Nuclear Information System (INIS)

    Jacob, Rainer

    2011-01-01

    Near-field optical microscopy has attracted remarkable attention, as it is the only technique that allows the investigation of local optical properties with a resolution far below the diffraction limit. Especially, the scattering-type near-field optical microscopy allows the nondestructive examination of surfaces without restrictions to the applicable wavelengths. However, its usability is limited by the availability of appropriate light sources. In the context of this work, this limit was overcome by the development of a scattering-type near-field microscope that uses a widely tunable free-electron laser as primary light source. In the theoretical part, it is shown that an optical near-field contrast can be expected when materials with different dielectric functions are combined. It is derived that these differences yield different scattering cross-sections for the coupled system of the probe and the sample. Those cross-sections define the strength of the near-field signal that can be measured for different materials. Hence, an optical contrast can be expected, when different scattering cross-sections are probed. This principle also applies to vertically stacked or even buried materials, as shown in this thesis experimentally for two sample systems. In the first example, the different dielectric functions were obtained by locally changing the carrier concentration in silicon by the implantation of boron. It is shown that the concentration of free charge-carriers can be deduced from the near-field contrast between implanted and pure silicon. For this purpose, two different experimental approaches were used, a non-interferometric one by using variable wavelengths and an interferometric one with a fixed wavelength. As those techniques yield complementary information, they can be used to quantitatively determine the effective carrier concentration. Both approaches yield consistent results for the carrier concentration, which excellently agrees with predictions from

  7. Characterization of near-field optical probes

    DEFF Research Database (Denmark)

    Vohnsen, Brian; Bozhevolnyi, Sergey I.

    1999-01-01

    Radiation and collection characteristics of four different near-field optical-fiber probes, namely, three uncoated probes and an aluminium-coated small-aperture probe, are investigated and compared. Their radiation properties are characterized by observation of light-induced topography changes...... in a photo-sensitive film illuminated with the probes, and it is confirmed that the radiated optical field is unambigiously confined only for the coated probe. Near-field optical imaging of a standing evanescent-wave pattern is used to compare the detection characteristics of the probes, and it is concluded...... that, for the imaging of optical-field intensity distributions containing predominantly evanescent-wave components, a sharp uncoated tip is the probe of choice. Complementary results obtained with optical phase-conjugation experiments with he uncoated probes are discussed in relation to the probe...

  8. Geochemistry of Natural Redox Fronts

    International Nuclear Information System (INIS)

    Hofmann, B.A.

    1999-05-01

    Redox fronts are important geochemical boundaries which need to be considered in safety assessment of deep repositories for radioactive waste. In most cases, selected host-rock formations will be reducing due to the presence of ferrous minerals, sulphides, etc. During construction and operation of the repository, air will be introduced into the formation. After repository closure, oxidising conditions may persist locally until all oxygen is consumed. In the case of high-level waste, radiolysis of water may provide an additional source of oxidants. Oxidising conditions within a repository are thus possible and potentially have a strong influence on the mobility of many elements. The rate of movement of redox fronts, the boundary between oxidising and reducing environments, and their influence on migrating radionuclides are thus important factors influencing repository performance. The present report is a review of elemental behaviour at natural redox fronts, based on published information and work of the author. Redox fronts are geochemically and geometrically variable manifestations of a global interface between generally oxidising geochemical milieux in contact with the atmosphere and generally reducing milieux in contact with rocks containing ferrous iron, sulphide and/or organic carbon. A classification of redox fronts based on a subdivision into continental near-surface, marine near-surface, and deep environments is proposed. The global redox interface is often located close to the surface of rocks and sediments and, sometimes, within bodies of water. Temperature conditions are close to ambient. A deeper penetration of the global redox front to depths of several kilometres is found in basins containing oxidised sediments (red beds) and in some hydrothermal circulation systems. Temperatures at such deep redox fronts may reach 200 o C. Both near-surface and deep redox fronts are sites of formation of economic deposits of redox-sensitive elements, particularly of

  9. The geochemistry of stable chlorine and bromine isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Eggenkamp, Hans [Onderzock and Beleving, Bussum (Netherlands)

    2014-11-01

    First book solely dedicated to the geochemistry of chlorine and bromine isotopes. Detailed description of analytical techniques, including their advantages and disadvantages. Indication of research fields where measurement of these isotopes is especially useful. This book provides detailed information on the history, analysis and applications of chlorine and bromine isotope geochemistry. Chlorine and bromine are geochemically unique as they prefer to exist as single charged negative ions. For this reason isotope fractionation reflects mostly processes that are not related to changes in the redox state and this fractionation is generally modest. The book will describe the processes that are most easily detected using these isotopes. Also isotope variations, and processes that cause them, measured in oxidised species such as perchlorates and in organic molecules will be described in this book.

  10. Geochemistry and ore prospecting

    International Nuclear Information System (INIS)

    Le Caignec, R.

    1954-01-01

    Applied geochemistry is a new technique which helps the geologist in detecting ore deposits. Some deposits, even when they are covered with rather thick surface structures, form around these zones where the infinitesimal content of some elements of soils or waters is notably different. These 'anomalies' may be contemporaneous to the deposit-structure (primary dispersion) or may have occurred later (secondary dispersion). Various factors rule these anomalies: ore-stability, soil homogeneity, water conditions, topography, vegetation, etc... Applied geochemistry is in fact the study of analysis techniques of metal traces in soils as well as the geological interpretation of observed anomalies. This report gives practical data on sampling methods, yields, costs and also on special problems of uranium geochemistry. (author) [fr

  11. Geochemistry of long lived transuranic actinides and fission products

    International Nuclear Information System (INIS)

    1992-01-01

    The IAEA initiated in 1987 a new Co-ordinated Research Programme (CRP) on geochemistry of long lived transuranic actinides and fission products for a duration of 5 years. The framework of the CRP consists of three main components: (1) development of a working hypothesis with focus on laboratory studies; (2) testing of the working hypothesis with the focus on the field studies; and (3) transport modelling. The contents of this document reflect the results reported on by a number of Member States who participated in this Co-ordinated Research Programme which investigated the geochemical processes and mechanisms which affect rock-water interactions and migration of the chemical elements in geological media as scientific background in support of safety assessments of repositories for high level radioactive wastes. Studies conducted considered the migration of the long lived radionuclides of Tc, I, Np and Pu in both the near and far field. The programme investigated natural occurrences and geochemical processes and mechanisms which may affect migration of the chemical elements under consideration in geological media which may be used for disposal of radioactive wastes. 47 refs, 9 figs, 1 tab

  12. Near-field characterization of plasmonic waveguides

    DEFF Research Database (Denmark)

    Zenin, Volodymyr

    2014-01-01

    simply by changing geometric parameters of the waveguide, keeping in mind the trade-off between confinement and propagation losses. A broad variety of plasmonic waveguides and waveguide components, including antennas for coupling the light in/out of the waveguide, requires correspondent characterization...... capabilities, especially on experimental side. The most straight-forward and powerful technique for such purpose is scanning near-field optical microscopy, which allows to probe and map near-field distribution and therefore becomes the main tool in this project. The detailed description of the used setups...

  13. Near-field probing of photonic crystal directional couplers

    DEFF Research Database (Denmark)

    Volkov, V. S.; Bozhevolnyi, S. I.; Borel, Peter Ingo

    2006-01-01

    We report the design, fabrication and characterization of a photonic crystal directional with a size of ~20 x 20 mm2 fabricated in silicon-on-insulator material. Using a scanning near-field optical microscope we demonstrate a high coupling efficiency for TM polarized light at telecom wavelengths....... By comparing the near-field optical images recorded in and after the directional coupler area, the features of light distribution are analyzed. Finally, the scanning near-field optical microscope observations are found to be in agreement with the transmission measurements conducted with the same sample....

  14. Asymmetric active nano-particles for directive near-field radiation

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Thorsen, Rasmus O.

    2016-01-01

    In this work, we demonstrate the potential of cylindrical active coated nano-particles with certain geometrical asymmetries for the creation of directive near-field radiation. The particles are excited by a near-by magnetic line source, and their performance characteristics are reported in terms...... of radiated power, near-field and power flow distributions as well as the far-field directivity....

  15. Merging metagenomics and geochemistry reveals environmental controls on biological diversity and evolution.

    Science.gov (United States)

    Alsop, Eric B; Boyd, Eric S; Raymond, Jason

    2014-05-28

    The metabolic strategies employed by microbes inhabiting natural systems are, in large part, dictated by the physical and geochemical properties of the environment. This study sheds light onto the complex relationship between biology and environmental geochemistry using forty-three metagenomes collected from geochemically diverse and globally distributed natural systems. It is widely hypothesized that many uncommonly measured geochemical parameters affect community dynamics and this study leverages the development and application of multidimensional biogeochemical metrics to study correlations between geochemistry and microbial ecology. Analysis techniques such as a Markov cluster-based measure of the evolutionary distance between whole communities and a principal component analysis (PCA) of the geochemical gradients between environments allows for the determination of correlations between microbial community dynamics and environmental geochemistry and provides insight into which geochemical parameters most strongly influence microbial biodiversity. By progressively building from samples taken along well defined geochemical gradients to samples widely dispersed in geochemical space this study reveals strong links between the extent of taxonomic and functional diversification of resident communities and environmental geochemistry and reveals temperature and pH as the primary factors that have shaped the evolution of these communities. Moreover, the inclusion of extensive geochemical data into analyses reveals new links between geochemical parameters (e.g. oxygen and trace element availability) and the distribution and taxonomic diversification of communities at the functional level. Further, an overall geochemical gradient (from multivariate analyses) between natural systems provides one of the most complete predictions of microbial taxonomic and functional composition. Clustering based on the frequency in which orthologous proteins occur among metagenomes

  16. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2004-01-01

    Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: thermometry, tracers, reaction mechanisms and chemostratigraphy. 52 refs., 11 figs., 2 tabs

  17. High-Density Near-Field Optical Disc Recording

    Science.gov (United States)

    Shinoda, Masataka; Saito, Kimihiro; Ishimoto, Tsutomu; Kondo, Takao; Nakaoki, Ariyoshi; Ide, Naoki; Furuki, Motohiro; Takeda, Minoru; Akiyama, Yuji; Shimouma, Takashi; Yamamoto, Masanobu

    2005-05-01

    We developed a high-density near-field optical recording disc system using a solid immersion lens. The near-field optical pick-up consists of a solid immersion lens with a numerical aperture of 1.84. The laser wavelength for recording is 405 nm. In order to realize the near-field optical recording disc, we used a phase-change recording media and a molded polycarbonate substrate. A clear eye pattern of 112 GB capacity with 160 nm track pitch and 50 nm bit length was observed. The equivalent areal density is 80.6 Gbit/in2. The bottom bit error rate of 3 tracks-write was 4.5× 10-5. The readout power margin and the recording power margin were ± 30.4% and ± 11.2%, respectively.

  18. Non-contact transportation using near-field acoustic levitation

    Science.gov (United States)

    Ueha; Hashimoto; Koike

    2000-03-01

    Near-field acoustic levitation, where planar objects 10 kg in weight can levitate stably near the vibrating plate, is successfully applied both to non-contact transportation of objects and to a non-contact ultrasonic motor. Transporting apparatuses and an ultrasonic motor have been fabricated and their characteristics measured. The theory of near-field acoustic levitation both for a piston-like sound source and a flexural vibration source is also briefly described.

  19. Radiation Entropy and Near-Field Thermophotovoltaics

    Science.gov (United States)

    Zhang, Zhuomin M.

    2008-08-01

    Radiation entropy was key to the original derivation of Planck's law of blackbody radiation, in 1900. This discovery opened the door to quantum mechanical theory and Planck was awarded the Nobel Prize in Physics in 1918. Thermal radiation plays an important role in incandescent lamps, solar energy utilization, temperature measurements, materials processing, remote sensing for astronomy and space exploration, combustion and furnace design, food processing, cryogenic engineering, as well as numerous agricultural, health, and military applications. While Planck's law has been fruitfully applied to a large number of engineering problems for over 100 years, questions have been raised about its limitation in micro/nano systems, especially at subwavelength distances or in the near field. When two objects are located closer than the characteristic wavelength, wave interference and photon tunneling occurs that can result in significant enhancement of the radiative transfer. Recent studies have shown that the near-field effects can realize emerging technologies, such as superlens, sub-wavelength light source, polariton-assisted nanolithography, thermophotovoltaic (TPV) systems, scanning tunneling thermal microscopy, etc. The concept of entropy has also been applied to explain laser cooling of solids as well as the second law efficiency of devices that utilize thermal radiation to produce electricity. However, little is known as regards the nature of entropy in near-field radiation. Some history and recent advances are reviewed in this presentation with a call for research of radiation entropy in the near field, due to the important applications in the optimization of thermophotovoltaic converters and in the design of practical systems that can harvest photon energies efficiently.

  20. Geochemistry of groundwater in the eastern Snake River Plain aquifer, Idaho National Laboratory and vicinity, eastern Idaho

    Science.gov (United States)

    Rattray, Gordon W.

    2018-05-30

    Nuclear research activities at the U.S. Department of Energy (DOE) Idaho National Laboratory (INL) in eastern Idaho produced radiochemical and chemical wastes that were discharged to the subsurface, resulting in detectable concentrations of some waste constituents in the eastern Snake River Plain (ESRP) aquifer. These waste constituents may pose risks to the water quality of the aquifer. In order to understand these risks to water quality the U.S. Geological Survey, in cooperation with the DOE, conducted a study of groundwater geochemistry to improve the understanding of hydrologic and chemical processes in the ESRP aquifer at and near the INL and to understand how these processes affect waste constituents in the aquifer.Geochemistry data were used to identify sources of recharge, mixing of water, and directions of groundwater flow in the ESRP aquifer at the INL. The geochemistry data were analyzed from 167 sample sites at and near the INL. The sites included 150 groundwater, 13 surface-water, and 4 geothermal-water sites. The data were collected between 1952 and 2012, although most data collected at the INL were collected from 1989 to 1996. Water samples were analyzed for all or most of the following: field parameters, dissolved gases, major ions, dissolved metals, isotope ratios, and environmental tracers.Sources of recharge identified at the INL were regional groundwater, groundwater from the Little Lost River (LLR) and Birch Creek (BC) valleys, groundwater from the Lost River Range, geothermal water, and surface water from the Big Lost River (BLR), LLR, and BC. Recharge from the BLR that may have occurred during the last glacial epoch, or paleorecharge, may be present at several wells in the southwestern part of the INL. Mixing of water at the INL primarily included mixing of surface water with groundwater from the tributary valleys and mixing of geothermal water with regional groundwater. Additionally, a zone of mixing between tributary valley water and

  1. RFID Antenna Near-field Characterization Using a New 3D Magnetic Field Probe

    Directory of Open Access Journals (Sweden)

    Kassem Jomaa

    2017-05-01

    Full Text Available In this paper the design of a new 3D magnetic field (H-field probe with a near-field scanning system is presented, then the near electromagnetic fields radiated by a Library RFID system is characterized. The proposed system is developed in order to determine the magnetic near-field emitted by electronic devices. The designed isotropic H-field probe consists of three orthogonal and identical loops each of diameter of 6 mm having 3 turns. The antenna factor of the designed probe is presented for a frequency range from 10 MHz to 1 GHz. The designed probe is tested and validated using a standard passive circuit as a device under test. An RFID reader antenna is also designed and simulated on HFSS (high frequency structural simulator and the radiated magnetic field, obtained by simulations, is then compared to the real measured one above the fabricated circuit. The obtained levels are checked if they satisfy the European and ICNIRP Electromagnetic Fields Guidelines.

  2. Summary report on the geochemistry of Yucca Mountain and environs

    International Nuclear Information System (INIS)

    Daniels, W.R.; Wolfsberg, K.; Rundberg, R.S.

    1982-12-01

    This report gives a detailed description of work at Los Alamos that will help resolve geochemical issues pertinent to siting a high-level nuclear waste repository in tuff at Yucca Mountain, Nevada. It is necessary to understand the properties and setting of the host tuff because this rock provides the first natural barrier to migration of waste elements from a repository. The geochemistry of tuff is being investigated with particular emphasis on retardation processes. This report addresses the various aspects of sorption by tuff, physical and chemical makeup of tuff, diffusion processes, tuff/groundwater chemistry, waste element chemistry under expected repository conditions, transport processes involved in porous and fracture flow, and geochemical and transport modeling

  3. Spherical near-field scanning at the Technical University of Denmark

    DEFF Research Database (Denmark)

    Hansen, J. E.; Jensen, F.

    1988-01-01

    The early work (1969-79) on spherical near-field antenna measurements at the Technical University of Denmark (TUD) is outlined. A spherical near-field transmission formula is described and the first probe-corrected spherical near-field measurements are discussed. The TUD-ESA (European Space Agency...

  4. The application of soil-gas geochemistry to precisely locate La Victoria fault near Paracotos (Venezuela)

    International Nuclear Information System (INIS)

    LaBrecque, J.J.; Rosales, P.A.; Cordoves, P.R.

    1999-01-01

    Full text: Measurements of radon (total radon, Radon-222 and Radon-220) and other soil-gases (CO 2 , O 2 and H 2 ) were performed routinely during 1998 and 1999 across a narrow valley near Paracotos, Venezuela in an attempt to precisely locate the La Victoria fault. The transect was about 300 meters long with eleven sampling points. The soil-gas probes were inserted to a depth of 45 cm in the beginning and later on completely to a depth of 63 cm. The radon sampling and measurements were accomplished with a Pylon AB-5 radiation monitor and Lucas scintillation cells. The other soil-gases were directly determined with an Anagas, CD95 monitor and an Infra-red Gas Analyzer (MKIIC) both coupled with a Hydrogen pod. The radon values for more than twenty different sampling periods over a two year period resulted with anomalous values between 75 and 150 meters along the transect. There were three consecutive anomalous values each time. But strangely, the anomalies of the radon values were in the form of a doublet at 116 and 141 meters rather than a simple single peak in the middle and the gas flow was similar for the sampling points between 75 and 150 meters. The graph of the relative CO 2 values were usually similar to the radon graphs but in some cases, the anomalous values were seen as a simple single peak and corresponded to the 141 meter sampling point. While the anomalous values of Hydrogen were usually in a form of a single peak that corresponded with 141 meter sampling point. Only a few times were values for Hydrogen higher than 100 ppm and detected at most of the sampling points, usually only one or two points resulted with small values near the 141 meter sampling point. Based on the radon values alone, we would have to conclude that the fault probably lies near or between the 116 and 141 meter sampling points, but with the additional data of the CO 2 and H 2 soil-gases one could say that the fault is probably near the 141 meter sampling point. Thus, we have

  5. Preliminary petrological and geochemical results from the Salton Sea Geothermal Field, California: A near-field natural analog of a radioactive waste repository in salt: Topical report No. 2

    International Nuclear Information System (INIS)

    Elders, W.A.; Cohen, L.H.; Williams, A.E.; Neville, S.; Collier, P.; Oakes, C.

    1986-03-01

    High concentrations of radionuclides and high temperatures are not naturally encountered in salt beds. For this reason, the Salton Sea Geothermal Field (SSGF) may be the best available geologic analog of some of the processes expected to occur in high level nuclear waste repositories in salt. Subsurface temperatures and brine concentrations in the SSGF span most of the temperature range and fluid inclusion brine range expected in a salt repository, and the clay-rich sedimentary rocks are similar to those which host bedded or domal salts. As many of the chemical processes observed in the SSGF are similar to those expected to occur in or near a salt repository, data derived from it can be used in the validation of geochemical models of the near-field of a repository in salt. This report describes preliminary data on petrology and geochemistry, emphasizing the distribution of rare earth elements and U and Th, of cores and cuttings from several deep wells chosen to span a range of temperature gradients and salinities. Subsurface temperature logs have been augmented by fluid inclusion studies, to reveal the effects of brines of varying temperature and salinity. The presence of brines with different oxygen isotopic signatures also indicate lack of mixing. Whole rock major, minor and trace element analyses and data on brine compositions are being used to study chemical migration in these sediments. 65 refs., 20 figs., 3 tabs

  6. Polarization resolved imaging with a reflection near-field optical microscope

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Xiao, Mufei; Hvam, Jørn Märcher

    1999-01-01

    Using a rigorous microscopic point-dipole description of probe-sample interactions, we study imaging with a reflection scanning near-field optical microscope. Optical content, topographical artifacts, sensitivity window-i.e., the scale on which near-field optical images represent mainly optical...... configuration is preferable to the cross-linear one, since it ensures more isotropic (in the surface plane) near-field imaging of surface features. The numerical results are supported with experimental near-field images obtained by using a reflection microscope with an uncoated fiber tip....

  7. Framework for near-field-communication-based geo-localization and personalization for Android-based smartphones--application in hospital environments.

    Science.gov (United States)

    Meng, Philipp; Fehre, Karsten; Rappelsberger, Andrea; Adlassnig, Klaus-Peter

    2014-01-01

    Various applications using near field communication (NFC) have been developed for the medical sector. As a method of short-range wireless contact-driven data transfer, NFC is a useful tool in medicine. It can be used to transfer data such as blood pressure, control adherence to medication, or transmit in vivo data. The first proposed general framework uses NFC as a mechanism for indoor geo-localization in hospitals. NFC geo-localization is economical compared to classical concepts using indoor GPS or WLAN triangulation, and the granularity of location retrieval can be defined at a tag level. Using this framework, we facilitate the development of medical applications that require exact indoor geo-localization. Multi-user Android systems are addressed in the second framework. Using private NFC tags, users are able to carry on their personal settings for enabled applications. This eliminates the need for multiple user accounts on common Android devices, improves usability, and eases technical administration. Based on the prototypes presented here, we show a novel concept of using NFC-enabled Android devices in hospital environments.

  8. Computational lens for the near field

    DEFF Research Database (Denmark)

    Carney, P. Scott; Franzin, Richard A.; Bozhevolnyi, Sergey I.

    2004-01-01

    A method is presented to reconstruct the structure of a scattering object from data acquired with a photon scanning tunneling microscope . The data may be understood to form a Gabor type near-field hologram and are obtained at a distance from the sample where the field is defocused and normally...

  9. Flow cytometric assessment of microbial abundance in the near-field area of seawater reverse osmosis concentrate discharge

    KAUST Repository

    Van Der Merwe, Riaan; Hammes, Frederik A.; Lattemann, Sabine; Amy, Gary L.

    2014-01-01

    The discharge of concentrate and other process waters from seawater reverse osmosis (SWRO) plant operations into the marine environment may adversely affect water quality in the near-field area surrounding the outfall. The main concerns

  10. Organic geochemistry and environmental instrumentation programs

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    The areas of research of the Organic Geochemistry Group include (1) computer-assisted gas chromatrographic, qualitative, and quantitative analyses of coal-derived complex mixtures; (2) chemodynamic measurements in complex organic mixtures to study the transport and transformation processes of chemicals in the environment; (3) bioassay-directed characterization of mutagenic polycyclic aromatic hydrocarbons in coal-derived materials; (4) chemical and toxicological evaluation of condensates from mild coal gasification processes; (5) development of rapid (high-pressure liquid chromatography) characterization techniques for primary aromatic amines in coal-derived liquids; (6) study of flame ionization detector response factors and chemical structure in gas chromatography; (7) development of a simple, portable device for preconcentrating airborne aromatic amines to be analyzed by portable liquid chromatography; (8) initial uptake and release studies of perchloroethylene and trichloroethylene in pine needles; (9) application of stable carbon isotope techniques in tracing environmental pollutants; (10) development of control technology for hydrazine fuels by neutralization with hypochlorite II. The Environmental Instrumentation group is engaged in research to develop and build prototype field-portable devices and instruments for the detection, identification, and quantification of volatile hazardous gases in a variety of environmental and workplace settings

  11. Near-field second-harmonic generation from gold nanoellipsoids

    Energy Technology Data Exchange (ETDEWEB)

    Celebrano, M; Zavelani-Rossi, M; Polli, D; Cerullo, G [Istituto di Fotonica e Nanotecnologie, CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Biagioni, P; Finazzi, M; Duo, L [LNESS - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Labardi, M; Allegrini, M [CNR-INFM, polyLab, Dipartimento di Fisica ' Enrico Fermi' , Universita di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); Grand, J; Adam, P M; Royer, P [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060 10010 Troyes cedex (France)

    2008-07-01

    Second-harmonic generation from single gold nanofabricated particles is experimentally investigated by a nonlinear scanning near-field optical microscope (SNOM). High peak power femtosecond polarized light pulses at the output of a hollow pyramid aperture allow for efficient second-harmonic imaging, with sub-100-nm spatial resolution and high contrast. The near-field nonlinear response is found to be directly related to both local surface plasmon resonances and particle morphology. The combined analysis of linear and second-harmonic SNOM images allows one to discriminate among near-field scattering, absorption and re-emission processes, which would not be possible with linear techniques alone. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Near-Field Source Localization by Using Focusing Technique

    Science.gov (United States)

    He, Hongyang; Wang, Yide; Saillard, Joseph

    2008-12-01

    We discuss two fast algorithms to localize multiple sources in near field. The symmetry-based method proposed by Zhi and Chia (2007) is first improved by implementing a search-free procedure for the reduction of computation cost. We present then a focusing-based method which does not require symmetric array configuration. By using focusing technique, the near-field signal model is transformed into a model possessing the same structure as in the far-field situation, which allows the bearing estimation with the well-studied far-field methods. With the estimated bearing, the range estimation of each source is consequently obtained by using 1D MUSIC method without parameter pairing. The performance of the improved symmetry-based method and the proposed focusing-based method is compared by Monte Carlo simulations and with Crammer-Rao bound as well. Unlike other near-field algorithms, these two approaches require neither high-computation cost nor high-order statistics.

  13. Near-Field Source Localization by Using Focusing Technique

    Directory of Open Access Journals (Sweden)

    Joseph Saillard

    2008-12-01

    Full Text Available We discuss two fast algorithms to localize multiple sources in near field. The symmetry-based method proposed by Zhi and Chia (2007 is first improved by implementing a search-free procedure for the reduction of computation cost. We present then a focusing-based method which does not require symmetric array configuration. By using focusing technique, the near-field signal model is transformed into a model possessing the same structure as in the far-field situation, which allows the bearing estimation with the well-studied far-field methods. With the estimated bearing, the range estimation of each source is consequently obtained by using 1D MUSIC method without parameter pairing. The performance of the improved symmetry-based method and the proposed focusing-based method is compared by Monte Carlo simulations and with Crammer-Rao bound as well. Unlike other near-field algorithms, these two approaches require neither high-computation cost nor high-order statistics

  14. Some variations of the Kristallin-I near-field model

    International Nuclear Information System (INIS)

    Smith, P.A.; Curti, E.

    1995-11-01

    The Kristallin-I project is an integrated analysis of the final disposal of vitrified high-level radioactive waste (HLW) in the crystalline basement of Northern Switzerland. It includes an analysis of the radiological consequences of radionuclide release from a repository. This analysis employs a chain of independent models for the near-field, geosphere and biosphere. In constructing these models, processes are incorporated that are believed to be relevant to repository safety, while other processes are neglected. In the present report, a set of simplified, steady-state models of the near-field is developed to investigate the possible effects of specific processes which are neglected in the time-dependent Kristallin-I near-field model. These processes are neglected, either because they are thought unlikely to occur to a significant degree, or because they are likely to make a positive contribution to the performance of the near-field barrier to radionuclide migration, but are insufficiently understood to justify incorporating them in a safety assessment. The aim of this report is to investigate whether the arguments for neglecting these processes in the Kristallin-I near-field model can be justified. (author) figs., tabs., refs

  15. Motion of Charged Particles near Magnetic Field Discontinuities

    International Nuclear Information System (INIS)

    Dodin, I.Y.; Fisch, N.J.

    2000-01-01

    The motion of charged particles in slowly changing magnetic fields exhibits adiabatic invariance even in the presence of abrupt magnetic discontinuities. Particles near discontinuities in magnetic fields, what we call ''boundary particles'', are constrained to remain near an arbitrarily fractured boundary even as the particle drifts along the discontinuity. A new adiabatic invariant applies to the motion of these particles

  16. Near-field optical recording based on solid immersion lens system

    Science.gov (United States)

    Hong, Tao; Wang, Jia; Wu, Yan; Li, Dacheng

    2002-09-01

    Near-field optical recording based on solid immersion lens (SIL) system has attracted great attention in the field of high-density data storage in recent years. The diffraction limited spot size in optical recording and lithography can be decreased by utilizing the SIL. The SIL near-field optical storage has advantages of high density, mass storage capacity and compatibility with many technologies well developed. We have set up a SIL near-field static recording system. The recording medium is placed on a 3-D scanning stage with the scanning range of 70×70×70μm and positioning accuracy of sub-nanometer, which will ensure the rigorous separation control in SIL system and the precision motion of the recording medium. The SIL is mounted on an inverted microscope. The focusing between long working distance objective and SIL can be monitored and observed by the CCD camera and eyes. Readout signal can be collected by a detector. Some experiments have been performed based on the SIL near-field recording system. The attempt of the near-field recording on photochromic medium has been made and the resolution improvement of the SIL has been presented. The influence factors in SIL near-field recording system are also discussed in the paper.

  17. SPATIAL Short Courses Build Expertise and Community in Isotope Geochemistry

    Science.gov (United States)

    Riggs, E. M.; Bowen, G. J.

    2015-12-01

    The SPATIAL short course at the University of Utah is designed for graduate students and professionals in the earth and environmental sciences from around the globe. An integral part of the broader, NSF-funded Inter-university Training for Continental-scale Ecology (ITCE) project, the course is an intensive two-week field, classroom and laboratory experience with internationally-known researchers as instructors. The course focuses on stable isotope geochemistry coupled with spatial analysis techniques. Participants do not typically know each other or this research community well upon entering. One of the stated goals of the overall project is to build a community of practice around these techniques. This design is common in many professional fields, but is not often applied at the graduate level nor formally assessed in the earth sciences. Paired pre- and post-tests were administered before the start and after the close of the short courses over 3 years. The survey is a set of instruments adapted from social-cognitive psychology measuring changes in identity and community with other items to measure content knowledge outcomes. We see a subtle, consistent convergence of identities between large-scale isotope geochemistry and participants' research areas. Results also show that the course generates an increase in understanding about stable isotopes' use and application. The data show the SPATIAL course is very effective at bringing students together socially with each other and with faculty to create an environment that fosters community and scientific cooperation. Semi-structured pre-and post- interviews were conducted to understand the program elements that generated gains in learning and community. Participants were selected based on initial responses on the pre-survey to capture the range of initial conditions for the group. Qualitative analysis shows that the major factors for participants were 1) ready access to researchers in an informal setting during the

  18. Thermodynamics of the near field

    International Nuclear Information System (INIS)

    Apps, J.A.

    1985-01-01

    The near field is normally taken to mean the part of the geologic setting of a repository that is affected by mechanical or thermal perturbations resulting from repository excavations and emplacement of radioactive waste. The near-field host rocks, the waste package, and the intervening backfill constitute a series of engineered and natural barriers that should be designed to initially prevent and subsequently control radionuclide release. Nuclear Regulatory Commission regulations 10 CFR part 60 specify that the waste package must not allow any release of radionuclides for at least 300 years, and preferably 1000 years. Thereafter, the release rate of any radionuclide is not to exceed on part in 100,000 per year of the inventory that is calculated to be present 1000 years after closure. In this paper, the author briefly outlines recent developments and identifies important fundamental research in thermodynamics and related areas that is needed to resolve some of the current uncertainties

  19. Near-Field Spectroscopy with Nanoparticles Deposited by AFM

    Science.gov (United States)

    Anderson, Mark S.

    2008-01-01

    An alternative approach to apertureless near-field optical spectroscopy involving an atomic-force microscope (AFM) entails less complexity of equipment than does a prior approach. The alternative approach has been demonstrated to be applicable to apertureless near-field optical spectroscopy of the type using an AFM and surface enhanced Raman scattering (SERS), and is expected to be equally applicable in cases in which infrared or fluorescence spectroscopy is used. Apertureless near-field optical spectroscopy is a means of performing spatially resolved analyses of chemical compositions of surface regions of nanostructured materials. In apertureless near-field spectroscopy, it is common practice to utilize nanostructured probe tips or nanoparticles (usually of gold) having shapes and dimensions chosen to exploit plasmon resonances so as to increase spectroscopic-signal strengths. To implement the particular prior approach to which the present approach is an alternative, it is necessary to integrate a Raman spectrometer with an AFM and to utilize a special SERS-active probe tip. The resulting instrumentation system is complex, and the tasks of designing and constructing the system and using the system to acquire spectro-chemical information from nanometer-scale regions on a surface are correspondingly demanding.

  20. Marine geochemistry of the rare earth elements: a review

    International Nuclear Information System (INIS)

    Kennedy, H.; Elderfield, H.

    1984-01-01

    The rare earth elements (REE) form a coherent group because of their systematic decrease in atomic radii with increasing atomic number and predominant +3 oxidation state. This makes them particularly useful in the study of marine geochemistry. The fact that two members of the group are often found in anomalous oxidation states allows a study of the fractionation of these REE from their neighbours and provides an insight into the geochemical behaviour of the REE in the marine environment. Thus the chemistry and relative abundances of the REE can be used to assess the origin and depositional environments of modern sediments. (author)

  1. Near-Field Resonance Microwave Tomography and Holography

    Science.gov (United States)

    Gaikovich, K. P.; Smirnov, A. I.; Yanin, D. V.

    2018-02-01

    We develop the methods of electromagnetic computer near-field microwave tomography of distributed subsurface inhomogeneities of complex dielectric permittivity and of holography (shape retrieval) of internally homogeneous subsurface objects. The methods are based on the solution of the near-field inverse scattering problem from measurements of the resonance-parameter variations of microwave probes above the medium surface. The capabilities of the proposed diagnostic technique are demonstrated in the numerical simulation for sensors with a cylindrical capacitor as a probe element, the edge capacitance of which is sensitive to subsurface inhomogeneities.

  2. Near-field optical microscope using a silicon-nitride probe

    NARCIS (Netherlands)

    van Hulst, N.F.; Moers, M.H.P.; Moers, M.H.P.; Noordman, O.F.J.; Noordman, O.F.J.; Tack, R.G.; Segerink, Franciscus B.; Bölger, B.; Bölger, B.

    1993-01-01

    Operation of an alternative near-field optical microscope is presented. The microscope uses a microfabricated silicon- nitride probe with integrated cantilever, as originally developed for force microscopy. The cantilever allows routine close contact near-field imaging o­n arbitrary surfaces without

  3. Review of international near-field modeling for high-level waste disposal

    International Nuclear Information System (INIS)

    Apted, M.J.; Andersson, K.; Pescatore, C.

    1993-01-01

    The primary components of nuclear waste repositories that mitigate radionuclide release are the near-field and the far-field subsystems. The near-field encompasses the waste package, which is composed of engineered barriers; the far-field includes the natural barriers. An international survey and review is being conducted on the latest developments in modeling of near-field performance, with particular emphasis on the conceptual and mathematical models for source-term calculations. The objectives of this review will be to establish the status and commonality among models and methods for assessing near-field performance, as well as to identify possible future needs for continued comparison and collaboration. In parallel with the technical evaluation, an international technical Workshop on near-field performance assessment will be held, in association with the Nuclear Energy Agency, on May 11-13, 1993 in Cadarache, France

  4. Near-field photon wave mechanics in the Lorenz gauge

    International Nuclear Information System (INIS)

    Keller, Ole

    2007-01-01

    Optical near-field interactions are studied theoretically in the perspective of photon wave mechanics paying particular attention to the dynamics in the wave-vector time domain. A unitary transformation is used to replace the scalar and longitudinal photon variables by so-called near-field and gauge photon variables. Dynamical equations are established for these types of photon variables, and it is shown that these equations are invariant against gauge transformations within the Lorenz gauge. The near-field photon is absent in the free-field limit, and the gauge photon can be eliminated by a suitable gauge transformation. Implicit solutions for the near-field, gauge, and transverse photon variables are obtained and discussed. The general theory is applied to an investigation of transverse photon propagation in a uniform solid-state plasma dominated by the diamagnetic field-matter interaction. It is found that the diamagnetic response can be incorporated in a quantum mechanical wave equation for a massive transverse photon. The Compton wave number of the massive photon equals the plasma wave number of the electron system. A dynamical equation describing the emission of a massive transverse photon from a mesoscopic source embedded in the plasma is finally established

  5. Control and near-field detection of surface plasmon interference patterns.

    Science.gov (United States)

    Dvořák, Petr; Neuman, Tomáš; Břínek, Lukáš; Šamořil, Tomáš; Kalousek, Radek; Dub, Petr; Varga, Peter; Šikola, Tomáš

    2013-06-12

    The tailoring of electromagnetic near-field properties is the central task in the field of nanophotonics. In addition to 2D optics for optical nanocircuits, confined and enhanced electric fields are utilized in detection and sensing, photovoltaics, spatially localized spectroscopy (nanoimaging), as well as in nanolithography and nanomanipulation. For practical purposes, it is necessary to develop easy-to-use methods for controlling the electromagnetic near-field distribution. By imaging optical near-fields using a scanning near-field optical microscope, we demonstrate that surface plasmon polaritons propagating from slits along the metal-dielectric interface form tunable interference patterns. We present a simple way how to control the resulting interference patterns both by variation of the angle between two slits and, for a fixed slit geometry, by a proper combination of laser beam polarization and inhomogeneous far-field illumination of the structure. Thus the modulation period of interference patterns has become adjustable and new variable patterns consisting of stripelike and dotlike motifs have been achieved, respectively.

  6. Uranium geochemistry, mineralogy, geology, exploration and resources

    International Nuclear Information System (INIS)

    De Vivo, B.

    1984-01-01

    This book comprises papers on the following topics: history of radioactivity; uranium in mantle processes; transport and deposition of uranium in hydrothermal systems at temperatures up to 300 0 C: Geological implications; geochemical behaviour of uranium in the supergene environment; uranium exploration techniques; uranium mineralogy; time, crustal evolution and generation of uranium deposits; uranium exploration; geochemistry of uranium in the hydrographic network; uranium deposits of the world, excluding Europe; uranium deposits in Europe; uranium in the economics of energy; role of high heat production granites in uranium province formation; and uranium deposits

  7. Building Practical Apertureless Scanning Near-Field Microscopy

    Science.gov (United States)

    Gungordu, M. Zeki

    The fundamental objective of this study is to establish a functional, practical apertureless type scanning near-field optical microscope, and to figure out the working mechanism behind it. Whereas a far-field microscope can measure the propagating field's components, this gives us little information about the features of the sample. The resolution is limited to about half of the wavelength of the illuminating light. On the other hand, the a-SNOM system enables achieving non-propagating components of the field, which provides more details about the sample's features. It is really difficult to measure because the amplitude of this field decays exponentially when the tip is moved away from the sample. The sharpness of the tip is the only limitation for resolution of the a-SNOM system. Consequently, the sharp tips are achieved by using electrochemical etching, and these tips are used to detect near-field signal. Separating the weak a-SNOM system signals from the undesired background signal, the higher demodulation background suppression is utilized by lock-in detection.

  8. Cosmological models in globally geodesic coordinates. II. Near-field approximation

    International Nuclear Information System (INIS)

    Liu Hongya

    1987-01-01

    A near-field approximation dealing with the cosmological field near a typical freely falling observer is developed within the framework established in the preceding paper [J. Math. Phys. 28, xxxx(1987)]. It is found that for the matter-dominated era the standard cosmological model of general relativity contains the Newtonian cosmological model, proposed by Zel'dovich, as its near-field approximation in the observer's globally geodesic coordinate system

  9. Optimization of s-Polarization Sensitivity in Apertureless Near-Field Optical Microscopy

    Directory of Open Access Journals (Sweden)

    Yuika Saito

    2012-01-01

    Full Text Available It is a general belief in apertureless near-field microscopy that the so-called p-polarization configuration, where the incident light is polarized parallel to the axis of the probe, is advantageous to its counterpart, the s-polarization configuration, where the incident light is polarized perpendicular to the probe axis. While this is true for most samples under common near-field experimental conditions, there are samples which respond better to the s-polarization configuration due to their orientations. Indeed, there have been several reports that have discussed such samples. This leads us to an important requirement that the near-field experimental setup should be equipped with proper sensitivity for measurements with s-polarization configuration. This requires not only creation of effective s-polarized illumination at the near-field probe, but also proper enhancement of s-polarized light by the probe. In this paper, we have examined the s-polarization enhancement sensitivity of near-field probes by measuring and evaluating the near-field Rayleigh scattering images constructed by a variety of probes. We found that the s-polarization enhancement sensitivity strongly depends on the sharpness of the apex of near-field probes. We have discussed the efficient value of probe sharpness by considering a balance between the enhancement and the spatial resolution, both of which are essential requirements of apertureless near-field microscopy.

  10. Specification of the near-Earth space environment with SHIELDS

    International Nuclear Information System (INIS)

    Jordanova, Vania Koleva; Delzanno, Gian Luca; Henderson, Michael Gerard; Godinez, Humberto C.; Jeffery, Christopher Andrew Munn

    2017-01-01

    Here, predicting variations in the near-Earth space environment that can lead to spacecraft damage and failure is one example of “space weather” and a big space physics challenge. A project recently funded through the Los Alamos National Laboratory (LANL) Directed Research and Development (LDRD) program aims at developing a new capability to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. The project goals are to understand the dynamics of the surface charging environment (SCE), the hot (keV) electrons representing the source and seed populations for the radiation belts, on both macro- and micro-scale. Important physics questions related to particle injection and acceleration associated with magnetospheric storms and substorms, as well as plasma waves, are investigated. These challenging problems are addressed using a team of world-class experts in the fields of space science and computational plasma physics, and state-of-the-art models and computational facilities. A full two-way coupling of physics-based models across multiple scales, including a global MHD (BATS-R-US) embedding a particle-in-cell (iPIC3D) and an inner magnetosphere (RAM-SCB) codes, is achieved. New data assimilation techniques employing in situ satellite data are developed; these provide an order of magnitude improvement in the accuracy in the simulation of the SCE. SHIELDS also includes a post-processing tool designed to calculate the surface charging for specific spacecraft geometry using the Curvilinear Particle-In-Cell (CPIC) code that can be used for reanalysis of satellite failures or for satellite design.

  11. Information Space, Information Field, Information Environment

    Directory of Open Access Journals (Sweden)

    Victor Ya. Tsvetkov

    2014-08-01

    Full Text Available The article analyzes information space, information field and information environment; shows that information space can be natural and artificial; information field is substantive and processual object and articulates the space property; information environment is concerned with some object and acts as the surrounding in relation to it and is considered with regard to it. It enables to define information environment as a subset of information space. It defines its passive description. Information environment can also be defined as a subset of information field. It corresponds to its active description.

  12. Supersonic acoustic intensity with statistically optimized near-field acoustic holography

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn

    2011-01-01

    The concept of supersonic acoustic intensity was introduced some years ago for estimating the fraction of the flow of energy radiated by a source that propagates to the far field. It differs from the usual (active) intensity by excluding the near-field energy resulting from evanescent waves...... to the information provided by the near-field acoustic holography technique. This study proposes a version of the supersonic acoustic intensity applied to statistically optimized near-field acoustic holography (SONAH). The theory, numerical results and an experimental study are presented. The possibility of using...

  13. Near-field radiative heat transfer between clusters of dielectric nanoparticles

    International Nuclear Information System (INIS)

    Dong, J.; Zhao, J.M.; Liu, L.H.

    2017-01-01

    In this work, we explore the near-field radiative heat transfer between two clusters of silicon carbide (SiC) nanoparticles using the many-body radiative heat transfer theory. The effects of fractal dimension of clusters, many-body interaction between nanoparticles and relative orientation of clusters on the thermal conductance are studied. Meanwhile, the applicability of the equivalent volume spheres (EVS) approximation for near-field radiative heat transfer between clusters is examined. It is observed that the thermal conductance is larger for clusters with larger fractal dimension, which is more significant in the near-field. The thermal conductance of EVS resembles that of the clusters, but EVS overestimates the conductance of clusters, especially in the near-field. Compared to the case of two nanoparticles, the conductance of nanoparticle clusters decays much slower with increasing distance in the near-field, but shares similar dependence on the distance in the far-field. The thermal conductance of SiC nanoparticle clusters is inhibited by the many-body interaction when surface phonon polariton is supported but enhanced at frequencies close to the resonance frequency. The total thermal conductance is decreased due to many-body interaction among particles in the cluster. The relative orientation between the clusters is also an important factor in the near-field, especially for clusters with lower fractal dimension. - Highlights: • Near-field radiative heat transfer between clusters of nanoparticles is studied. • The many-body radiative heat transfer theory is applied for rigorous analysis. • The accuracy of equivalent volume spheres approximation is examined. • Clusters with larger fractal dimension have larger radiative thermal conductance. • Many-body interaction inhibits the total radiative thermal conductance.

  14. New developments in near-field acoustic holography

    NARCIS (Netherlands)

    Roozen, N.B.; Geerlings, A.C.; Verhaar, B.T.; Vliegenthart, T.

    2007-01-01

    In the field of noise-control engineering, information about the individual strength, andlocation, of the most dominant sources is of vital importance. This information allows theacoustic engineer to take effective measures in his effort to reduce the emitted acoustic noiselevels. Near-field

  15. Review of speciation and solubility of radionuclides in the near and far field. Pt. 1

    International Nuclear Information System (INIS)

    Smith-Briggs, J.L.

    1992-01-01

    This report represents Part 1 in a series of three reports which review the speciation and solubility of radionuclides in the near and far field. Part 1 reviews the research funded by UK Nirex Ltd (NIREX) and the Department of the Environment into the solubility and speciation of radionuclides in the near and far fields of a radioactive waste repository. The review is focused on the particular situation prevailing in the UK. UK Nirex Limited are currently planning the development of a deep geological repository for low and intermediate level wastes. In the basic design it is envisaged that the waste material would be immobilised and packed into steel or concrete containers. These containers would be placed in vaults and then backfilled with a cemetitious grout. (Author)

  16. Near-field levitated quantum optomechanics with nanodiamonds

    Science.gov (United States)

    Juan, M. L.; Molina-Terriza, G.; Volz, T.; Romero-Isart, O.

    2016-08-01

    We theoretically show that the dipole force of an ensemble of quantum emitters embedded in a dielectric nanosphere can be exploited to achieve near-field optical levitation. The key ingredient is that the polarizability from the ensemble of embedded quantum emitters can be larger than the bulk polarizability of the sphere, thereby enabling the use of repulsive optical potentials and consequently the levitation using optical near fields. In levitated cavity quantum optomechanics, this could be used to boost the single-photon coupling by combining larger polarizability to mass ratio, larger field gradients, and smaller cavity volumes while remaining in the resolved sideband regime and at room temperature. A case study is done with a nanodiamond containing a high density of silicon-vacancy color centers that is optically levitated in the evanescent field of a tapered nanofiber and coupled to a high-finesse microsphere cavity.

  17. Near field optics and nanoscopy

    CERN Document Server

    Fillard, J P

    1996-01-01

    This book contains the most recent information on optical nanoscopy. Far-Field and Near-Field properties on e.m. waves are presented which illustrate how optical images can be obtained from sub-micron objects. Scanning Probe techniques and computer processing are covered here. An explanation is given on how propagating photons or evanescent waves can behave over distances shorter than the wavelength, taking into account the presence of small objects. Quantum tunneling of photons is explained comparatively with the electron mechanism. Technical details are given on photon tunneling microscopes.

  18. Geochemistry and origin of metamorphosed mafic rocks from the Lower Paleozoic Moretown and Cram Hill Formations of North-Central Vermont: Delamination magmatism in the western New England appalachians

    Science.gov (United States)

    Coish, Raymond; Kim, Jonathan; Twelker, Evan; Zolkos, Scott P.; Walsh, Gregory J.

    2015-01-01

    The Moretown Formation, exposed as a north-trending unit that extends from northern Vermont to Connecticut, is located along a critical Appalachian litho-tectonic zone between the paleomargin of Laurentia and accreted oceanic terranes. Remnants of magmatic activity, in part preserved as metamorphosed mafic rocks in the Moretown Formation and the overlying Cram Hill Formation, are a key to further understanding the tectonic history of the northern Appalachians. Field relationships suggest that the metamorphosed mafic rocks might have formed during and after Taconian deformation, which occurred at ca. 470 to 460 Ma. Geochemistry indicates that the sampled metamorphosed mafic rocks were mostly basalts or basaltic andesites. The rocks have moderate TiO2 contents (1–2.5 wt %), are slightly enriched in the light-rare earth elements relative to the heavy rare earths, and have negative Nb-Ta anomalies in MORB-normalized extended rare earth element diagrams. Their chemistry is similar to compositions of basalts from western Pacific extensional basins near volcanic arcs. The metamorphosed mafic rocks of this study are similar in chemistry to both the pre-Silurian Mount Norris Intrusive Suite of northern Vermont, and also to some of Late Silurian rocks within the Lake Memphremagog Intrusive Suite, particularly the Comerford Intrusive Complex of Vermont and New Hampshire. Both suites may be represented among the samples of this study. The geochemistry of all samples indicates that parental magmas were generated in supra-subduction extensional environments during lithospheric delamination.

  19. Near-field mapping by laser ablation of PMMA coatings

    DEFF Research Database (Denmark)

    Fiutowski, J.; Maibohm, C.; Kostiucenko, O.

    2011-01-01

    The optical near-field of lithography-defined gold nanostructures, arranged into regular arrays on a gold film, is characterized via ablation of a polymer coating by laser illumination. The method utilizes femto-second laser pulses from a laser scanning microscope which induces electrical field...... that the different stages in the ablation process can be controlled and characterized making the technique suitable for characterizing optical near-fields of metal nanostructures....

  20. Influence factor analysis of atmospheric electric field monitoring near ground under different weather conditions

    International Nuclear Information System (INIS)

    Wan, Haojiang; Wei, Guanghui; Cui, Yaozhong; Chen, Yazhou

    2013-01-01

    Monitoring of atmospheric electric field near ground plays a critical role in atmospheric environment detecting and lightning warning. Different environmental conditions (e.g. buildings, plants, weather, etc.) have different influences on the data's coherence in an atmospheric electric field detection network. In order to study the main influence factors of atmospheric electric field monitoring under different weather conditions, with the combination of theoretical analysis and experiments, the electric field monitoring data on the ground and on the top of a building are compared in fair weather and thunderstorm weather respectively in this paper. The results show that: In fair weather, the field distortion due to the buildings is the main influence factor on the electric field monitoring. In thunderstorm weather, the corona ions produced from the ground, besides the field distortion due to the buildings, can also influence the electric field monitoring results.

  1. Flow cytometric assessment of microbial abundance in the near-field area of seawater reverse osmosis concentrate discharge

    KAUST Repository

    Van Der Merwe, Riaan

    2014-06-01

    The discharge of concentrate and other process waters from seawater reverse osmosis (SWRO) plant operations into the marine environment may adversely affect water quality in the near-field area surrounding the outfall. The main concerns are the increase in salt concentration in receiving waters, which results in a density increase and potential water stratification near the outfall, and possible increases in turbidity, e.g., due to the discharge of filter backwash waters. Changes in ambient water quality may affect microbial abundance in the area, for example by hindering the photosynthesis process or disrupting biogenesis. It is widely accepted that marine biodiversity is lower in more extreme conditions, such as high salinity environments. As aquatic microbial communities respond very rapidly to changes in their environment, they can be used as indicators for monitoring ambient water quality. The objective of this study was to assess possible changes in microbial abundance as a result of concentrate discharge into the near-field area (<. 25. m) surrounding the outfall of the King Abdullah University of Science and Technology (KAUST) SWRO plant. Flow cytometric (FCM) analysis was conducted in order to rapidly determine microbial abundance on a single-cell level in 107 samples, taken by diving, from the discharge area, the intake area and two control sites. FCM analysis combined the measurement of distinct scatter of cells and particles, autofluorescence of cyanobacteria and algae, and fluorescence after staining of nucleic acids with SYBR® Green for a total bacterial count. The results indicate that changes in microbial abundance in the near-field area of the KAUST SWRO outfall are minor and appear to be the result of a dilution effect rather than a direct impact of the concentrate discharge. © 2014 Elsevier B.V.

  2. Some variations of the Kristallin-I near-field model

    Energy Technology Data Exchange (ETDEWEB)

    Smith, P A; Curti, E [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1995-11-01

    The Kristallin-I project is an integrated analysis of the final disposal of vitrified high-level radioactive waste (HLW) in the crystalline basement of Northern Switzerland. It includes an analysis of the radiological consequences of radionuclide release from a repository. This analysis employs a chain of independent models for the near-field, geosphere and biosphere. In constructing these models, processes are incorporated that are believed to be relevant to repository safety, while other processes are neglected. In the present report, a set of simplified, steady-state models of the near-field is developed to investigate the possible effects of specific processes which are neglected in the time-dependent Kristallin-I near-field model. These processes are neglected, either because (i) they are thought unlikely to occur to a significant degree, or because (ii) they are likely to make a positive contribution to the performance of the near-field barrier to radionuclide migration, but are insufficiently understood to justify incorporating them in a safety assessment. The aim of this report is to investigate whether the arguments for neglecting these processes in the Kristallin-I near-field model can be justified. This work addresses the following topics: - radionuclide transport at the bentonite-host rock interface, - canister settlement, -chemical conditions and radionuclide transport at the glass-bentonite interface. (author) figs., tabs., refs.

  3. Some variations of the Kristallin-I near-field model

    International Nuclear Information System (INIS)

    Smith, P.A.; Curti, E.

    1995-11-01

    The Kristallin-I project is an integrated analysis of the final disposal of vitrified high-level radioactive waste (HLW) in the crystalline basement of Northern Switzerland. It includes an analysis of the radiological consequences of radionuclide release from a repository. This analysis employs a chain of independent models for the near-field, geosphere and biosphere. In constructing these models, processes are incorporated that are believed to be relevant to repository safety, while other processes are neglected. In the present report, a set of simplified, steady-state models of the near-field is developed to investigate the possible effects of specific processes which are neglected in the time-dependent Kristallin-I near-field model. These processes are neglected, either because (i) they are thought unlikely to occur to a significant degree, or because (ii) they are likely to make a positive contribution to the performance of the near-field barrier to radionuclide migration, but are insufficiently understood to justify incorporating them in a safety assessment. The aim of this report is to investigate whether the arguments for neglecting these processes in the Kristallin-I near-field model can be justified. This work addresses the following topics: - radionuclide transport at the bentonite-host rock interface, - canister settlement, -chemical conditions and radionuclide transport at the glass-bentonite interface. (author) figs., tabs., refs

  4. Scanning near-field optical microscopy and near-field optical probes: properties, fabrication, and control of parameters

    International Nuclear Information System (INIS)

    Dryakhlushin, V F; Veiko, V P; Voznesenskii, N B

    2007-01-01

    A brief review of modern applications of scanning near-field optical (SNO) devices in microscopy, spectroscopy, and lithography is presented in the introduction. The problem of the development of SNO probes, as the most important elements of SNO devices determining their resolution and efficiency, is discussed. Based on the works of the authors, two different methods for fabricating SNO probes by using the adiabatic tapering of an optical fibre are considered: the laser-heated mechanical drawing and chemical etching. A nondestructive optical method for controlling the nanometre aperture of SNO probes is proposed, substantiated, and tested experimentally. The method is based on the reconstruction of a near-field source with the help of a theoretical algorithm of the inverse problem from the experimental far-filed intensity distribution. Some prospects for a further refinement of the construction and technology of SNO probes are discussed. (optical microscopy)

  5. Modelling the near-Earth space environment using LDEF data

    Science.gov (United States)

    Atkinson, Dale R.; Coombs, Cassandra R.; Crowell, Lawrence B.; Watts, Alan J.

    1992-01-01

    Near-Earth space is a dynamic environment, that is currently not well understood. In an effort to better characterize the near-Earth space environment, this study compares the results of actual impact crater measurement data and the Space Environment (SPENV) Program developed in-house at POD, to theoretical models established by Kessler (NASA TM-100471, 1987) and Cour-Palais (NASA SP-8013, 1969). With the continuing escalation of debris there will exist a definite hazard to unmanned satellites as well as manned operations. Since the smaller non-trackable debris has the highest impact rate, it is clearly necessary to establish the true debris environment for all particle sizes. Proper comprehension of the near-Earth space environment and its origin will permit improvement in spacecraft design and mission planning, thereby reducing potential disasters and extreme costs. Results of this study directly relate to the survivability of future spacecraft and satellites that are to travel through and/or reside in low Earth orbit (LEO). More specifically, these data are being used to: (1) characterize the effects of the LEO micrometeoroid an debris environment on satellite designs and components; (2) update the current theoretical micrometeoroid and debris models for LEO; (3) help assess the survivability of spacecraft and satellites that must travel through or reside in LEO, and the probability of their collision with already resident debris; and (4) help define and evaluate future debris mitigation and disposal methods. Combined model predictions match relatively well with the LDEF data for impact craters larger than approximately 0.05 cm, diameter; however, for smaller impact craters, the combined predictions diverge and do not reflect the sporadic clouds identified by the Interplanetary Dust Experiment (IDE) aboard LDEF. The divergences cannot currently be explained by the authors or model developers. The mean flux of small craters (approximately 0.05 cm diameter) is

  6. A Compact RFID Reader Antenna for UHF Near-Field and Far-Field Operations

    Directory of Open Access Journals (Sweden)

    Lai Xiao zheng

    2013-01-01

    Full Text Available A compact loop antenna is presented for mobile ultrahigh frequency (UHF radio frequency identification (RFID application. This antenna, printed on a 0.8 mm thick FR4 substrate with a small size of 31 mm × 31 mm, achieves good impedance bandwidth from 897 to 928 MHz, which covers USA RFID Band (902–928 MHz. The proposed loop configuration, with a split-ring resonator (SRR coupled inside it, demonstrates strong and uniform magnetic field distribution in the near-field antenna region. Its linearly polarized radiation pattern provides available far-field gain. Finally, the reading capabilities of antenna are up to 56 mm for near-field and 1.05 m for far-field UHF RFID operations, respectively.

  7. Performance analysis of near-field thermophotovoltaic devices considering absorption distribution

    International Nuclear Information System (INIS)

    Park, K.; Basu, S.; King, W.P.; Zhang, Z.M.

    2008-01-01

    This paper elucidates the energy transfer and conversion processes in near-field thermophotovoltaic (TPV) systems, considering local radiation absorption and photocurrent generation in the TPV cell. Radiation heat transfer in a multilayered structure is modeled using the fluctuation-dissipation theorem, and the electric current generation is evaluated based on the photogeneration and recombination of electron-hole pairs in different regions of the TPV cell. The effects of near-field radiation on the photon penetration depth, photocurrent generation, and quantum efficiency are examined in the spectral region of interest. The detailed analysis performed in the present work demonstrates that, while the near-field operation can enhance the power throughput, the conversion efficiency is not much improved and may even be reduced. Subsequently, a modified design of near-field TPV systems is proposed to improve the efficiency

  8. Planetary science. Low-altitude magnetic field measurements by MESSENGER reveal Mercury's ancient crustal field.

    Science.gov (United States)

    Johnson, Catherine L; Phillips, Roger J; Purucker, Michael E; Anderson, Brian J; Byrne, Paul K; Denevi, Brett W; Feinberg, Joshua M; Hauck, Steven A; Head, James W; Korth, Haje; James, Peter B; Mazarico, Erwan; Neumann, Gregory A; Philpott, Lydia C; Siegler, Matthew A; Tsyganenko, Nikolai A; Solomon, Sean C

    2015-05-22

    Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data. Copyright © 2015, American Association for the Advancement of Science.

  9. Convergence analysis in near-field imaging

    International Nuclear Information System (INIS)

    Bao, Gang; Li, Peijun

    2014-01-01

    This paper is devoted to the mathematical analysis of the direct and inverse modeling of the diffraction by a perfectly conducting grating surface in the near-field regime. It is motivated by our effort to analyze recent significant numerical results, in order to solve a class of inverse rough surface scattering problems in near-field imaging. In a model problem, the diffractive grating surface is assumed to be a small and smooth deformation of a plane surface. On the basis of the variational method, the direct problem is shown to have a unique weak solution. An analytical solution is introduced as a convergent power series in the deformation parameter by using the transformed field and Fourier series expansions. A local uniqueness result is proved for the inverse problem where only a single incident field is needed. On the basis of the analytic solution of the direct problem, an explicit reconstruction formula is presented for recovering the grating surface function with resolution beyond the Rayleigh criterion. Error estimates for the reconstructed grating surface are established with fully revealed dependence on such quantities as the surface deformation parameter, measurement distance, noise level of the scattering data, and regularity of the exact grating surface function. (paper)

  10. Transfer function and near-field detection of evanescent waves

    DEFF Research Database (Denmark)

    Radko, Ylia P.; Bozhevolnyi, Sergey I.; Gregersen, Niels

    2006-01-01

    of collection and illumination modes. Making use of a collection near-field microscope with a similar fiber tip illuminated by an evanescent field, we measure the collected power as a function of the field spatial frequency in different polarization configurations. Considering a two-dimensional probe...... for the transfer function, which is derived by introducing an effective pointof (dipolelike) detection inside the probe tip. It is found to be possible to fit reasonably well both the experimental and the simulation data for evanescent field components, implying that the developed approximation of the near......-field transfer function can serve as a simple, rational, and sufficiently reliable means of fiber probe characterization....

  11. Development of JNC geological disposal technical information integration system for geological environment field

    International Nuclear Information System (INIS)

    Tsuchiya, Makoto; Ueta, Shinzo; Ohashi, Toyo

    2004-02-01

    Enormous data on geology, geological structure, hydrology, geochemistry and rock properties should be obtained by various investigation/study in the geological disposal study. Therefore, 'JNC Geological Disposal Technical Information Integration System for Geological Environment Field' was developed in order to manage these data systematically and to support/promote the use of these data for the investigators concerned. The system is equipped with data base to store the information of the works and the background information of the assumptions built up in the works on each stage of data flow ('instigative', → 'data sampling' → interpretation' → conceptualization/modeling/simulation' → 'output') in the geological disposal study. In this system the data flow is shown as 'plan' composed of task' and 'work' to be done in the geological disposal study. It is possible to input the data to the database and to refer data from the database by using GUI that shows the data flow as 'plan'. The system was installed to the server computer possessed by JNC and the system utilities were checked on both the server computer and client computer also possessed by JNC. (author)

  12. THz near-field imaging of biological tissues employing synchrotronradiation

    Energy Technology Data Exchange (ETDEWEB)

    Schade, Ulrich; Holldack, Karsten; Martin, Michael C.; Fried,Daniel

    2004-12-23

    Terahertz scanning near-field infrared microscopy (SNIM) below 1 THz is demonstrated. The near-field technique benefits from the broadband and highly brilliant coherent synchrotron radiation (CSR) from an electron storage ring and from a detection method based on locking onto the intrinsic time structure of the synchrotron radiation. The scanning microscope utilizes conical wave guides as near-field probes with apertures smaller than the wavelength. Different cone approaches have been investigated to obtain maximum transmittance. Together with a Martin-Puplett spectrometer the set-up enables spectroscopic mapping of the transmittance of samples well below the diffraction limit. Spatial resolution down to about lambda/40 at 2 wavenumbers (0.06 THz) is derived from the transmittance spectra of the near-field probes. The potential of the technique is exemplified by imaging biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 mu-m at about 12 wave numbers (0.36 THz). The THz near-field images reveal distinct structural differences of leaves from different plants investigated. The technique presented also allows spectral imaging of bulky organic tissues. Human teeth samples of various thicknesses have been imaged between 2 and 20 wavenumbers (between 0.06and 0.6 THz). Regions of enamel and dentin within tooth samples are spatially and spectrally resolved, and buried caries lesions are imaged through both the outer enamel and into the underlying dentin.

  13. Near-field Spectroscopy of Surface Plasmons in Flat Gold Nanoparticles

    International Nuclear Information System (INIS)

    Achermann, Marc; Shuford, Kevin L.; Schatz, George C.; Dahanayaka, D.H.; Bumm, Lloyd A; Klimov, Victor I.

    2007-01-01

    We use near-field interference spectroscopy with a broadband femtosecond, white-light probe to study local surface plasmon resonances in flat gold nanoparticles (FGNPs). Depending on nanoparticle dimensions, local near-field extinction spectra exhibit none, one, or two resonances in the range of visible wavelengths (1.6-2.6 eV). The measured spectra can be accurately described in terms of interference between the field emitted by the probe aperture and the field reradiated by driven FGNP surface plasmon oscillations. The measured resonances are in good agreement with those predicted by calculations using discrete dipole approximation. We observe that the amplitudes of these resonances are dependent upon the spatial position of the near-field probe, which indicates the possibility of spatially selective excitation of specific plasmon modes

  14. Photocurrent mapping of near-field optical antenna resonances

    KAUST Repository

    Barnard, Edward S.; Pala, Ragip A.; Brongersma, Mark L.

    2011-01-01

    An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data. Here, we demonstrate a photodetector platform that uses a silicon-on-insulator substrate to spectrally and spatially map the absolute values of enhanced fields near any type of optical antenna by transducing local electric fields into photocurrent. We are able to quantify the resonant optical and materials properties of nanoscale (∼50nm) and wavelength-scale (∼1μm) metallic antennas as well as high-refractive-index semiconductor antennas. The data agree well with light-scattering measurements, full-field simulations and intuitive resonator models. © 2011 Macmillan Publishers Limited. All rights reserved.

  15. Photocurrent mapping of near-field optical antenna resonances

    KAUST Repository

    Barnard, Edward S.

    2011-08-21

    An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data. Here, we demonstrate a photodetector platform that uses a silicon-on-insulator substrate to spectrally and spatially map the absolute values of enhanced fields near any type of optical antenna by transducing local electric fields into photocurrent. We are able to quantify the resonant optical and materials properties of nanoscale (∼50nm) and wavelength-scale (∼1μm) metallic antennas as well as high-refractive-index semiconductor antennas. The data agree well with light-scattering measurements, full-field simulations and intuitive resonator models. © 2011 Macmillan Publishers Limited. All rights reserved.

  16. Near-field enhanced thermionic energy conversion for renewable energy recycling

    Science.gov (United States)

    Ghashami, Mohammad; Cho, Sung Kwon; Park, Keunhan

    2017-09-01

    This article proposes a new energy harvesting concept that greatly enhances thermionic power generation with high efficiency by exploiting the near-field enhancement of thermal radiation. The proposed near-field enhanced thermionic energy conversion (NETEC) system is uniquely configured with a low-bandgap semiconductor cathode separated from a thermal emitter with a subwavelength gap distance, such that a significant amount of electrons can be photoexcited by near-field thermal radiation to contribute to the enhancement of thermionic current density. We theoretically demonstrate that the NETEC system can generate electric power at a significantly lower temperature than the standard thermionic generator, and the energy conversion efficiency can exceed 40%. The obtained results reveal that near-field photoexcitation can enhance the thermionic power output by more than 10 times, making this hybrid system attractive for renewable energy recycling.

  17. Geochemical evolution of the near field of a KBS-3 repository

    International Nuclear Information System (INIS)

    Arcos, David; Grandia, Fidel; Domenech, Cristina

    2006-09-01

    The Swedish concept developed by SKB for deep radioactive waste disposal, envisages an engineered multi-barrier system surrounding the nuclear waste (near field). In the present study we developed a numerical model to assess the geochemical evolution of the near field in the frame of the SKB's safety assessment SR-Can. These numerical models allow us to predict the long-term geochemical evolution of the near field system by means of reactive-transport codes and the information gathered in underground laboratory experiments and natural analogues. Two different scenarios have been defined to model this near field evolution, according to the pathway used by groundwater to contact the near field: a) through a fracture in the host rock intersecting the deposition hole; and b) through the material used to backfill the deposition tunnel. Moreover, we also modelled the effect of different groundwater compositions reaching the near field, as the up-rise of deep-seated brines and the intrusion of ice-melting derived groundwater. We also modelled the effect of the thermal stage due to the heat generated by spent fuel on the geochemical evolution of the bentonite barrier

  18. Geochemical evolution of the near field of a KBS-3 repository

    Energy Technology Data Exchange (ETDEWEB)

    Arcos, David; Grandia, Fidel; Domenech, Cristina [Enviros Spain S.L., Barcelona (Spain)

    2006-09-15

    The Swedish concept developed by SKB for deep radioactive waste disposal, envisages an engineered multi-barrier system surrounding the nuclear waste (near field). In the present study we developed a numerical model to assess the geochemical evolution of the near field in the frame of the SKB's safety assessment SR-Can. These numerical models allow us to predict the long-term geochemical evolution of the near field system by means of reactive-transport codes and the information gathered in underground laboratory experiments and natural analogues. Two different scenarios have been defined to model this near field evolution, according to the pathway used by groundwater to contact the near field: a) through a fracture in the host rock intersecting the deposition hole; and b) through the material used to backfill the deposition tunnel. Moreover, we also modelled the effect of different groundwater compositions reaching the near field, as the up-rise of deep-seated brines and the intrusion of ice-melting derived groundwater. We also modelled the effect of the thermal stage due to the heat generated by spent fuel on the geochemical evolution of the bentonite barrier.

  19. DOE workshop: Sedimentary systems, aqueous and organic geochemistry

    International Nuclear Information System (INIS)

    1993-07-01

    A DOE workshop on sedimentary systems, aqueous and organic geochemistry was held July 15-16, 1993 at Lawrence Berkeley Laboratory. Papers were organized into several sections: Fundamental Properties, containing papers on the thermodynamics of brines, minerals and aqueous electrolyte solutions; Geochemical Transport, covering 3-D imaging of drill core samples, hydrothermal geochemistry, chemical interactions in hydrocarbon reservoirs, fluid flow model application, among others; Rock-Water Interactions, with presentations on stable isotope systematics of fluid/rock interaction, fluid flow and petotectonic evolution, grain boundary transport, sulfur incorporation, tracers in geologic reservoirs, geothermal controls on oil-reservoir evolution, and mineral hydrolysis kinetics; Organic Geochemistry covered new methods for constraining time of hydrocarbon migration, kinetic models of petroleum formation, mudstones in burial diagenesis, compound-specific carbon isotope analysis of petroleums, stability of natural gas, sulfur in sedimentary organic matter, organic geochemistry of deep ocean sediments, direct speciation of metal by optical spectroscopies; and lastly, Sedimentary Systems, covering sequence stratigraphy, seismic reflectors and diagenetic changes in carbonates, geochemistry and origin of regional dolomites, and evidence of large comet or asteroid impacts at extinction boundaries

  20. DOE workshop: Sedimentary systems, aqueous and organic geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    1993-07-01

    A DOE workshop on sedimentary systems, aqueous and organic geochemistry was held July 15-16, 1993 at Lawrence Berkeley Laboratory. Papers were organized into several sections: Fundamental Properties, containing papers on the thermodynamics of brines, minerals and aqueous electrolyte solutions; Geochemical Transport, covering 3-D imaging of drill core samples, hydrothermal geochemistry, chemical interactions in hydrocarbon reservoirs, fluid flow model application, among others; Rock-Water Interactions, with presentations on stable isotope systematics of fluid/rock interaction, fluid flow and petotectonic evolution, grain boundary transport, sulfur incorporation, tracers in geologic reservoirs, geothermal controls on oil-reservoir evolution, and mineral hydrolysis kinetics; Organic Geochemistry covered new methods for constraining time of hydrocarbon migration, kinetic models of petroleum formation, mudstones in burial diagenesis, compound-specific carbon isotope analysis of petroleums, stability of natural gas, sulfur in sedimentary organic matter, organic geochemistry of deep ocean sediments, direct speciation of metal by optical spectroscopies; and lastly, Sedimentary Systems, covering sequence stratigraphy, seismic reflectors and diagenetic changes in carbonates, geochemistry and origin of regional dolomites, and evidence of large comet or asteroid impacts at extinction boundaries.

  1. Janus and Huygens Dipoles: Near-Field Directionality Beyond Spin-Momentum Locking

    Science.gov (United States)

    Picardi, Michela F.; Zayats, Anatoly V.; Rodríguez-Fortuño, Francisco J.

    2018-03-01

    Unidirectional scattering from circularly polarized dipoles has been demonstrated in near-field optics, where the quantum spin-Hall effect of light translates into spin-momentum locking. By considering the whole electromagnetic field, instead of its spin component alone, near-field directionality can be achieved beyond spin-momentum locking. This unveils the existence of the Janus dipole, with side-dependent topologically protected coupling to waveguides, and reveals the near-field directionality of Huygens dipoles, generalizing Kerker's condition. Circular dipoles, together with Huygens and Janus sources, form the complete set of all possible directional dipolar sources in the far- and near-field. This allows the designing of directional emission, scattering, and waveguiding, fundamental for quantum optical technology, integrated nanophotonics, and new metasurface designs.

  2. Near-field millimeter - wave imaging of nonmetallic materials

    International Nuclear Information System (INIS)

    Gopalsami, N.; Bakhtiari, S.; Raptis, A.C.

    1996-01-01

    A near-field millimeter-wave (mm-wave) imaging system has been designed and built in the 94-GHz range for on-line inspection of nonmetallic (dielectric) materials. The imaging system consists of a transceiver block coupled to an antenna that scans the material to be imaged; a reflector plate is placed behind the material. A quadrature IF mixer in the transceiver block enables measurement of in-phase and quadrature-phase components of reflected signals with respect to the transmitted signal. All transceiver components, with the exception of the Gunn-diode oscillator and antenna, were fabricated in uniform blocks and integrated and packaged into a compact unit (12.7 x 10.2 x 2.5 cm). The objective of this work is to test the applicability of a near-field compact mm-wave sensor for on-line inspection of sheetlike materials such as paper, fabrics, and plastics. This paper presents initial near-field mm-wave images of paper and fabric samples containing known artifacts

  3. On the use of numerical modelling for near-field pollutant dispersion in urban environments − A review

    International Nuclear Information System (INIS)

    Lateb, M.; Meroney, R.N.; Yataghene, M.; Fellouah, H.; Saleh, F.; Boufadel, M.C.

    2016-01-01

    This article deals with the state-of-the-art of experimental and numerical studies carried out regarding air pollutant dispersion in urban environments. Since the simulation of the dispersion field around buildings depends strongly on the correct simulation of the wind-flow structure, the studies performed during the past years on the wind-flow field around buildings are reviewed. This work also identifies errors that can produce poor results when numerically modelling wind flow and dispersion fields around buildings in urban environments. Finally, particular attention is paid to the practical guidelines developed by researchers to establish a common methodology for verification and validation of numerical simulations and/or to assist and support the users for a better implementation of the computational fluid dynamics (CFD) approach. - This review article enlightens the reader on the use of CFD for pollutant dispersion. Errors that induce poor results and critical parameters that compromise significantly the accuracy and reliability are identified.

  4. Modeled near-field environment porosity modifications due to coupled thermohydrologic and geochemical processes

    International Nuclear Information System (INIS)

    Glassley, W. E.; Nitao, J. J.

    1998-01-01

    Heat deposited by waste packages in nuclear waste repositories can modify rock properties by instigating mineral dissolution and precipitation along hydrothermal flow pathways. Modeling this reactive transport requires coupling fluid flow to permeability changes resulting from dissolution and precipitation. Modification of the NUFT thermohydrologic (TH) code package to account for this coupling in a simplified geochemical system has been used to model the time- dependent change in porosity, permeability, matrix and fracture saturation, and temperature in the vicinity of waste-emplacement drifts, using conditions anticipated for the potential Yucca Mountain repository. The results show, within a few hundred years, dramatic porosity reduction approximately 10 m above emplacement drifts. Most of this reduction is attributed to deposition of solute load at the boiling front, although some of it also results from decreasing temperature along the flow path. The actual distribution of the nearly sealed region is sensitive to the time- dependent characteristics of the thermal load imposed on the environment and suggests that the geometry of the sealed region can be engineered by managing the waste-emplacement strategy

  5. Near field communication recent developments and library implications

    CERN Document Server

    McHugh, Sheli

    2014-01-01

    Near Field Communication is a radio frequency technology that allows objects, such as mobile phones, computers, tags, or posters, to exchange information wirelessly across a small distance. This report on the progress of Near Field Communication reviews the features and functionality of the technology and summarizes the broad spectrum of its current and anticipated applications. We explore the development of NFC technology in recent years, introduce the major stakeholders in the NFC ecosystem, and project its movement toward mainstream adoption. Several examples of early implementation of NFC

  6. Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

    Science.gov (United States)

    Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

    2015-02-01

    We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz.

  7. REFREP: a near-field model for a spent fuel repository

    International Nuclear Information System (INIS)

    Hautojaervi, A.; Vieno, T.

    1988-05-01

    A code package for near-field performance analysis of spent fuel disposal has been programmed. The conceptual models used are shortly described in connection with th model presentations. For more comprehensive descriptions the previous safety analysis and references therein are referred. The REFREP package consists of nine individual modules performing the following tasks: viewing and updating of the data files (UPDATE), calculating of the breaching times of canisters (CORRFLUX), calculating of stationary nuclide release rates using solubility values (MASSFLUX), calculating of actinide inventories from chain decay (INVENT), calculating of elemental inventories of actinides (ELEMENT), calculating of nuclide release rates according to congruent release (CONGRUNT), performing of sensitivity analysis for one variable (SENSIT), summing of release rates from individual canisters according to given probability distributions of canister breaching times (PROBREL), and forming a compact data file including all the input values (DATAOUT). The results have been shown to agree very well with the results of the previous safety analysis where near-field analysis was performed by means of separate codes and manual calculation. The REFREP model offers already at this stage some additional features to the old procedures and more versatile capabilities can easyly be added into the modular structure of the package. REFREP has been developed in a VAX-environment. Some changes in file handling might be necessary if the code is transferred to another computer

  8. Radiative heat transfer in the extreme near field.

    Science.gov (United States)

    Kim, Kyeongtae; Song, Bai; Fernández-Hurtado, Víctor; Lee, Woochul; Jeong, Wonho; Cui, Longji; Thompson, Dakotah; Feist, Johannes; Reid, M T Homer; García-Vidal, Francisco J; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

    2015-12-17

    Radiative transfer of energy at the nanometre length scale is of great importance to a variety of technologies including heat-assisted magnetic recording, near-field thermophotovoltaics and lithography. Although experimental advances have enabled elucidation of near-field radiative heat transfer in gaps as small as 20-30 nanometres (refs 4-6), quantitative analysis in the extreme near field (less than 10 nanometres) has been greatly limited by experimental challenges. Moreover, the results of pioneering measurements differed from theoretical predictions by orders of magnitude. Here we use custom-fabricated scanning probes with embedded thermocouples, in conjunction with new microdevices capable of periodic temperature modulation, to measure radiative heat transfer down to gaps as small as two nanometres. For our experiments we deposited suitably chosen metal or dielectric layers on the scanning probes and microdevices, enabling direct study of extreme near-field radiation between silica-silica, silicon nitride-silicon nitride and gold-gold surfaces to reveal marked, gap-size-dependent enhancements of radiative heat transfer. Furthermore, our state-of-the-art calculations of radiative heat transfer, performed within the theoretical framework of fluctuational electrodynamics, are in excellent agreement with our experimental results, providing unambiguous evidence that confirms the validity of this theory for modelling radiative heat transfer in gaps as small as a few nanometres. This work lays the foundations required for the rational design of novel technologies that leverage nanoscale radiative heat transfer.

  9. Near field communications handbook

    CERN Document Server

    Ahson, Syed A; Furht, Borko

    2011-01-01

    Near Field Communication, or NFC, is a short-range high frequency wireless communication technology that enables the exchange of data between devices over about a decimeter. The technology is a simple extension of the ISO 14443 proximity-card standard (contact less card, RFID) that combines the interface of a smart card and a reader into a single device with practical implications. A complete reference for NFC, this handbook provides technical information about all aspects of NFC, as well as applications. It covers basic concepts as well as research grade material and includes a discussion of

  10. Technical Work Plan for: Near Field Environment: Engineered System: Radionuclide Transport Abstraction Model Report

    Energy Technology Data Exchange (ETDEWEB)

    J.D. Schreiber

    2006-12-08

    This technical work plan (TWP) describes work activities to be performed by the Near-Field Environment Team. The objective of the work scope covered by this TWP is to generate Revision 03 of EBS Radionuclide Transport Abstraction, referred to herein as the radionuclide transport abstraction (RTA) report. The RTA report is being revised primarily to address condition reports (CRs), to address issues identified by the Independent Validation Review Team (IVRT), to address the potential impact of transport, aging, and disposal (TAD) canister design on transport models, and to ensure integration with other models that are closely associated with the RTA report and being developed or revised in other analysis/model reports in response to IVRT comments. The RTA report will be developed in accordance with the most current version of LP-SIII.10Q-BSC and will reflect current administrative procedures (LP-3.15Q-BSC, ''Managing Technical Product Inputs''; LP-SIII.2Q-BSC, ''Qualification of Unqualified Data''; etc.), and will develop related Document Input Reference System (DIRS) reports and data qualifications as applicable in accordance with prevailing procedures. The RTA report consists of three models: the engineered barrier system (EBS) flow model, the EBS transport model, and the EBS-unsaturated zone (UZ) interface model. The flux-splitting submodel in the EBS flow model will change, so the EBS flow model will be validated again. The EBS transport model and validation of the model will be substantially revised in Revision 03 of the RTA report, which is the main subject of this TWP. The EBS-UZ interface model may be changed in Revision 03 of the RTA report due to changes in the conceptualization of the UZ transport abstraction model (a particle tracker transport model based on the discrete fracture transfer function will be used instead of the dual-continuum transport model previously used). Validation of the EBS-UZ interface model

  11. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  12. Calcium stable isotope geochemistry

    International Nuclear Information System (INIS)

    Gausonne, Nikolaus; Schmitt, Anne-Desiree; Heuser, Alexander; Wombacher, Frank; Dietzel, Martin; Tipper, Edward; Schiller, Martin

    2016-01-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  13. Laser terahertz emission microscopy with near-field probes

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Mittleman, Daniel M.

    2016-01-01

    Using an AFM, an optical near-field image at 800 nm of a dipole antenna for THz emission is measured, and by simultaneously collecting the emitted THz radiation, the laser light confined under the AFM probe gives a THz emission resolution of less than 50 nm.......Using an AFM, an optical near-field image at 800 nm of a dipole antenna for THz emission is measured, and by simultaneously collecting the emitted THz radiation, the laser light confined under the AFM probe gives a THz emission resolution of less than 50 nm....

  14. Quantification of source-term profiles from near-field geochemical models

    International Nuclear Information System (INIS)

    McKinley, I.G.

    1985-01-01

    A geochemical model of the near-field is described which quantitatively treats the processes of engineered barrier degradation, buffering of aqueous chemistry by solid phases, nuclide solubilization and transport through the near-field and release to the far-field. The radionuclide source-terms derived from this model are compared with those from a simpler model used for repository safety analysis. 10 refs., 2 figs., 2 tabs

  15. Applied Geochemistry Special Issue on Environmental geochemistry of modern mining

    Science.gov (United States)

    Seal, Robert R.; Nordstrom, D. Kirk

    2015-01-01

    Environmental geochemistry is an integral part of the mine-life cycle, particularly for modern mining. The critical importance of environmental geochemistry begins with pre-mining baseline characterization and the assessment of environmental risks related to mining, continues through active mining especially in water and waste management practices, and culminates in mine closure. The enhanced significance of environmental geochemistry to modern mining has arisen from an increased knowledge of the impacts that historical and active mining can have on the environment, and from new regulations meant to guard against these impacts. New regulations are commonly motivated by advances in the scientific understanding of the environmental impacts of past mining. The impacts can be physical, chemical, and biological in nature. The physical challenges typically fall within the purview of engineers, whereas the chemical and biological challenges typically require a multidisciplinary array of expertise including geologists, geochemists, hydrologists, microbiologists, and biologists. The modern mine-permitting process throughout most of the world now requires that potential risks be assessed prior to the start of mining. The strategies for this risk assessment include a thorough characterization of pre-mining baseline conditions and the identification of risks specifically related to the manner in which the ore will be mined and processed, how water and waste products will be managed, and what the final configuration of the post-mining landscape will be.In the Fall 2010, the Society of Economic Geologists held a short course in conjunction with the annual meeting of the Geological Society of America in Denver, Colorado (USA) to examine the environmental geochemistry of modern mining. The intent was to focus on issues that are pertinent to current and future mines, as opposed to abandoned mines, which have been the focus of numerous previous short courses. The geochemical

  16. A Broadband UHF Tag Antenna For Near-Field and Far-Field RFID Communications

    Directory of Open Access Journals (Sweden)

    M. Dhaouadi

    2014-12-01

    Full Text Available The paper deals with the design of passive broadband tag antenna for Ultra-High Frequency (UHF band. The antenna is intended for both near and far fields Radio Frequency Identification (RFID applications. The meander dipole tag antenna geometry modification is designed for frequency bandwidth increasing. The measured bandwidth of the proposed broadband Tag antenna is more than 140 MHz (820–960 MHz, which can cover the entire UHF RFID band. A comparison between chip impedance of datasheet and the measured chip impedance has been used in our simulations. The proposed progressive meandered antenna structure, with an overall size of 77 mm × 14 mm × 0.787 mm, produces strong and uniform magnetic field distribution in the near-field zone. The antenna impedance is matched to common UHF chips in market simply by tuning its capacitive and inductive values since a perfect matching is required in the antenna design in order to enhance the near and the far field communications. Measurements confirm that the designed antenna exhibits good performance of Tag identification for both near-field and far-field UHF RFID applications.

  17. Future directions in geobiology and low-temperature geochemistry

    Science.gov (United States)

    Freeman, Katherine H.; Goldhaber, M.B.

    2011-01-01

    Humanity is confronted with an enormous challenge, as succinctly stated by the late Steven Schneider (2001; quoted by Jantzen 2004*): “Humans are forcing the Earth’s environmental systems to change at a rate that is more advanced than their knowledge of the consequences.” Geobiologists and low-temperature geochemists characterize material from the lithosphere, hydrosphere, atmosphere, and biosphere to understand processes operating within and between these components of the Earth system from the atomic to the planetary scale. For this reason, the interwoven disciplines of geobiology and low-temperature geochemistry are central to understanding and ultimately predicting the behavior of these life-sustaining systems. We present here comments and recommendations from the participants of a workshop entitled “Future Directions in Geobiology and Low-Temperature Geochemistry,” hosted by the Carnegie Institution of Washington, Geophysical Laboratory, Washington, DC, on 27–28 August 2010. The goal of the workshop was to suggest ways to leverage the vast intellectual and analytical capabilities of our diverse scientific community to characterize the Earth’s past, present, and future geochemical habitat as we enter the second decade of what E. O. Wilson dubbed “the century of the environment.”

  18. Small scale changes of geochemistry and flow field due to transient heat storage in aquifers

    Science.gov (United States)

    Bauer, S.; Boockmeyer, A.; Li, D.; Beyer, C.

    2013-12-01

    Heat exchangers in the subsurface are increasingly installed for transient heat storage due to the need of heating or cooling of buildings as well as the interim storage of heat to compensate for the temporally fluctuating energy production by wind or solar energy. For heat storage to be efficient, high temperatures must be achieved in the subsurface. Significant temporal changes of the soil and groundwater temperatures however effect both the local flow field by temperature dependent fluid parameters as well as reactive mass transport through temperature dependent diffusion coefficients, geochemical reaction rates and mineral equilibria. As the use of heat storage will be concentrated in urban areas, the use of the subsurface for (drinking) water supply and heat storage will typically coincide and a reliable prognosis of the processes occurring is needed. In the present work, the effects of a temporal variation of the groundwater temperature, as induced by a local heat exchanger introduced into a groundwater aquifer, are studied. For this purpose, the coupled non-isothermal groundwater flow, heat transport and reactive mass transport is simulated in the near filed of such a heat exchanger. By explicitly discretizing and incorporating the borehole, the borehole cementation and the heat exchanger tubes, a realistic geometrical and process representation is obtained. The numerical simulation code OpenGeoSys is used in this work, which incorporates the required processes of coupled groundwater flow, heat and mass transport as well as temperature dependent geochemistry. Due to the use of a Finite Element Method, a close representation of the geometric effects can be achieved. Synthetic scenario simulations for typical settings of salt water formations in northern Germany are used to investigate the geochemical effects arising from a high temperature heat storage by quantifying changes in groundwater chemistry and overall reaction rates. This work presents the

  19. Studies of solar magnetic fields. V. The true average field strengths near the poles

    Energy Technology Data Exchange (ETDEWEB)

    Howard, R [Hale Observatories, Pasadena, Calif. (USA)

    1977-05-01

    An estimate of the average magnetic field strength at the poles of the Sun from Mount Wilson measurements is made by comparing low latitude magnetic measurements in the same regions made near the center of the disk and near the limb. There is still some uncertainty because the orientation angle of the field lines in the meridional plane is unknown, but the most likely possibility is that the true average field strengths are about twice the measured values (0-2 G), with an absolute upper limit on the underestimation of the field strengths of about a factor 5. The measurements refer to latitudes below about 80/sup 0/.

  20. Unidirectional wireless power transfer using near-field plates

    International Nuclear Information System (INIS)

    Imani, Mohammadreza F.; Grbic, Anthony

    2015-01-01

    One of the obstacles preventing wireless power transfer from becoming ubiquitous is their leakage of power: high-amplitude electromagnetic fields that can interfere with other electronic devices, increase health concerns, or hinder power metering. In this paper, we present near-field plates (NFPs) as a novel method to tailor the electromagnetic fields generated by a wireless power transfer system while maintaining high efficiency. NFPs are modulated arrays or surfaces designed to form prescribed near-field patterns. The NFP proposed in this paper consists of an array of loaded loops that are designed to confine the electromagnetic fields of a resonant transmitting loop to the desired direction (receiving loop) while suppressing fields in other directions. The step-by-step design procedure for this device is outlined. Two NFPs are designed and examined in full-wave simulation. Their performance is shown to be in close agreement with the design predictions, thereby verifying the proposed design and operation. A NFP is also fabricated and experimentally shown to form a unidirectional wireless power transfer link with high efficiency

  1. Unidirectional wireless power transfer using near-field plates

    Energy Technology Data Exchange (ETDEWEB)

    Imani, Mohammadreza F., E-mail: mohamad.imani@gmail.com [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Grbic, Anthony [Radiation Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2015-05-14

    One of the obstacles preventing wireless power transfer from becoming ubiquitous is their leakage of power: high-amplitude electromagnetic fields that can interfere with other electronic devices, increase health concerns, or hinder power metering. In this paper, we present near-field plates (NFPs) as a novel method to tailor the electromagnetic fields generated by a wireless power transfer system while maintaining high efficiency. NFPs are modulated arrays or surfaces designed to form prescribed near-field patterns. The NFP proposed in this paper consists of an array of loaded loops that are designed to confine the electromagnetic fields of a resonant transmitting loop to the desired direction (receiving loop) while suppressing fields in other directions. The step-by-step design procedure for this device is outlined. Two NFPs are designed and examined in full-wave simulation. Their performance is shown to be in close agreement with the design predictions, thereby verifying the proposed design and operation. A NFP is also fabricated and experimentally shown to form a unidirectional wireless power transfer link with high efficiency.

  2. Near-Field Nanolasers based on Nonradiating Anapole Modes

    KAUST Repository

    Gongora, J. S. Totero; Miroshnichenko, Andrey E.; Kivshar, Yuri S.; Fratalocchi, Andrea

    2016-01-01

    By employing ab-initio simulations of Maxwell-Bloch equations with a source of quantum noise, we study a new laser concept based on photonic dark-matter nanostructures that emit only in the near-field, with no far-field radiation pattern.

  3. Near-Field Nanolasers based on Nonradiating Anapole Modes

    KAUST Repository

    Gongora, J. S. Totero

    2016-05-31

    By employing ab-initio simulations of Maxwell-Bloch equations with a source of quantum noise, we study a new laser concept based on photonic dark-matter nanostructures that emit only in the near-field, with no far-field radiation pattern.

  4. The inside–outside duality for inverse scattering problems with near field data

    International Nuclear Information System (INIS)

    Lechleiter, Armin; Peters, Stefan

    2015-01-01

    We derive an inside–outside duality for near field scattering data generated by time-harmonic scattering of acoustic point sources from a sound-soft scatterer. This duality in particular rigorously characterizes interior Dirichlet eigenvalues of the scattering object by near field operators for an interval of wave numbers. As a crucial new concept to prove this duality we exploit the numerical ranges of certain modifications of these near field operators. We also show that our theoretical results can be numerically used to approximate interior Dirichlet eigenvalues from multi-frequency near field measurements. (paper)

  5. Phase retrieval in near-field measurements by array synthesis

    DEFF Research Database (Denmark)

    Wu, Jian; Larsen, Flemming Holm

    1991-01-01

    The phase retrieval problem in near-field antenna measurements is formulated as an array synthesis problem. As a test case, a particular synthesis algorithm has been used to retrieve the phase of a linear array......The phase retrieval problem in near-field antenna measurements is formulated as an array synthesis problem. As a test case, a particular synthesis algorithm has been used to retrieve the phase of a linear array...

  6. Maximal near-field radiative heat transfer between two plates

    OpenAIRE

    Nefzaoui, Elyes; Ezzahri, Younès; Drevillon, Jérémie; Joulain, Karl

    2013-01-01

    International audience; Near-field radiative transfer is a promising way to significantly and simultaneously enhance both thermo-photovoltaic (TPV) devices power densities and efficiencies. A parametric study of Drude and Lorentz models performances in maximizing near-field radiative heat transfer between two semi-infinite planes separated by nanometric distances at room temperature is presented in this paper. Optimal parameters of these models that provide optical properties maximizing the r...

  7. Modular model for Mercury's magnetospheric magnetic field confined within the average observed magnetopause.

    Science.gov (United States)

    Korth, Haje; Tsyganenko, Nikolai A; Johnson, Catherine L; Philpott, Lydia C; Anderson, Brian J; Al Asad, Manar M; Solomon, Sean C; McNutt, Ralph L

    2015-06-01

    Accurate knowledge of Mercury's magnetospheric magnetic field is required to understand the sources of the planet's internal field. We present the first model of Mercury's magnetospheric magnetic field confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. The field of internal origin is approximated by a dipole of magnitude 190 nT R M 3 , where R M is Mercury's radius, offset northward by 479 km along the spin axis. External field sources include currents flowing on the magnetopause boundary and in the cross-tail current sheet. The cross-tail current is described by a disk-shaped current near the planet and a sheet current at larger (≳ 5  R M ) antisunward distances. The tail currents are constrained by minimizing the root-mean-square (RMS) residual between the model and the magnetic field observed within the magnetosphere. The magnetopause current contributions are derived by shielding the field of each module external to the magnetopause by minimizing the RMS normal component of the magnetic field at the magnetopause. The new model yields improvements over the previously developed paraboloid model in regions that are close to the magnetopause and the nightside magnetic equatorial plane. Magnetic field residuals remain that are distributed systematically over large areas and vary monotonically with magnetic activity. Further advances in empirical descriptions of Mercury's magnetospheric external field will need to account for the dependence of the tail and magnetopause currents on magnetic activity and additional sources within the magnetosphere associated with Birkeland currents and plasma distributions near the dayside magnetopause.

  8. Gold nanocone probes for near-field scanning optical microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zeeb, Bastian; Schaefer, Christian; Nill, Peter; Fleischer, Monika; Kern, Dieter P. [Institute of Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, 72076 Tuebingen (Germany)

    2010-07-01

    Apertureless near-field scanning optical microscopy (ANSOM) provides the possibility to collect simultaneously high-resolution topographical and sub-diffraction limited optical information from a surface. When optically excited, the scanning probes act as optical antennae with a strong near-field enhancement near the tip apex. Spatial resolution and optical near-field enhancement depend strongly on the properties and geometry of the scanning probe - in particular on very sharp tip radii. Various possibilities for fabricating good antennae have been pursued. Most commonly, scanning probes consist of electrochemically etched gold wires which are sharp but not well-defined in geometry. We present two different approaches for ultra sharp and well-defined antennae based upon fabricating gold nanocones with a tip radius smaller than 10 nm which can be used in ANSOM. A transfer process is presented that can be used to attach single gold nanocones to non-metallic probes such as sharp glass fiber tips. Alternatively, new processes are presented to fabricate cones directly on pillars of different materials such as silicon or bismuth, which can be applied to cantilever tips for ANSOM scanning applications.

  9. Organic, Gas, and Element Geochemistry of Hydrothermal Fluids of the Newly Discovered Extensive Hydrothermal Area in the Wallis and Futuna Region (SW Pacific

    Directory of Open Access Journals (Sweden)

    C. Konn

    2018-01-01

    Full Text Available Two newly discovered hydrothermal vent fields of the Wallis and Futuna region, Kulo Lasi and Fatu Kapa, were sampled for fluid geochemistry. A great geochemical diversity was observed and assigned to the diversity of lithologies as well as the occurrence of various processes. Kulo Lasi fluids likely formed by interaction with fresh volcanic rocks, phase separation, and mixing with magmatic fluid. Conversely, the geochemistry of the Fatu Kapa fluids would be mostly due to water/felsic lavas reactions. In terms of organic geochemistry, fluids from both fields were found to be enriched in formate, acetate, and semivolatile organic compounds (SVOCs: n-alkanes, n-fatty acids, and polyaromatic hydrocarbons (PAHs. Concentrations of SVOCs reached a few ppb at most. The distribution patterns of SVOCs indicated that several processes and sources, at once of biogenic, thermogenic, and abiogenic types, likely controlled organic geochemistry. Although the contribution of each process remains unknown, the mere presence of organics at the μM level has strong implications for metal dispersion (cycles, deposition (ore-forming, and bioavailability (ecosystems, especially as our fluxes estimations suggest that back-arc hosted vent fields could contribute as much as MOR to the global ocean heat and mass budget.

  10. The near-field acoustic levitation of high-mass rotors

    International Nuclear Information System (INIS)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B.

    2014-01-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope

  11. The near-field acoustic levitation of high-mass rotors

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2014-10-15

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  12. The near-field acoustic levitation of high-mass rotors.

    Science.gov (United States)

    Hong, Z Y; Lü, P; Geng, D L; Zhai, W; Yan, N; Wei, B

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  13. Near-field scanning optical microscopy based nanostructuring of glass

    International Nuclear Information System (INIS)

    Chimmalgi, A; Hwang, D J; Grigoropoulos, C P

    2007-01-01

    Nanofabrication, at lateral resolutions beyond the capability of conventional optical lithography techniques, is demonstrated here. Femtosecond laser was used in conjunction with Near-field Scanning Optical Microscopes (NSOMs) to nanostructure thin metal films. Also, the possibility of using these nanostructured metal films as masks to effectively transfer the pattern to the underlying substrate by wet etching process is shown. Two different optical nearfiled processing schemes were studied for near-field nanostructuring. In the first scheme, local field enhancement in the near-field of a scanning probe microscope (SPM) probe tip irradiated with femtosecond laser pulses was utilized (apertureless NSOM mode) and as a second approach, femtosecond laser beam was spatially confined by cantilevered NSOM fiber tip (apertured NOSM mode). The minimized heat- and shock-affected areas introduced during ultrafast laser based machining process, allows processing of even high conductivity thin metal films with minimized formation of any interfacial compounds between the metal films and the underlying substrate. Potential applications of this method may be in the fields of nanolithography, nanofluidics, nanoscale chemical and gas sensors, high-density data storage, nano-opto-electronics, as well as biotechnology related applications

  14. Field noise near ferromagnetic films

    Science.gov (United States)

    McMichael, Robert; Liu, Hau-Jian; Yoon, Seungha

    Thermally driven magnetization fluctuations can be viewed as a nuisance noise source or as interesting physics. For example, mag noise in a field sensor may set the minimum detectable field of that sensor. On the other hand, the field noise spectrum reflects the dynamics of the magnetic components, which are essential for device operation. Here, we model the field noise spectrum near the surface of a magnetic film due to thermal spin waves, and we calculate its effect on the T1 relaxation rate of a nearby nitrogen-vacancy (NV) center spin. The model incorporates four components: the spin wave dispersion of the magnetization in a finite-thickness film, thermal excitation of spin waves, the coupling geometry between waves in the film and an external point dipole and finally, the relaxation dynamics of the NV spin. At a distance of 100 nm above a 50 nm thick permalloy film, we find that the strongest stray fields are along the film normal and parallel to the magnetization, on the order of 1 mA m-1 Hz- 1 / 2 or 1 nT Hz- 1 / 2, yielding relaxation times on the order of 10 μs. The spin wave field noise can dominate the intrinsic relaxation, (T1 1 ms) of the NV center spin.

  15. Contribution to uranium geochemistry in intrusive granites

    International Nuclear Information System (INIS)

    Coulomb, R.

    1959-01-01

    This work aims to define the position of a certain number of French granitic deposits within the field of the geochemistry of granites in general, and of the geochemistry of uranium in particular. The regions concerned are: - 3 French Hercynian ranges, in the Vendee, in Brittany and in the Morvan, - 1 African range, probably precambrian, of the Hoggar. For each range, the petrochemical framework is first of all determined and then the degree of chemical homogeneity of the rocks is evaluated. In the petrochemical groups thus obtained the geochemical behaviour of the uranium is studied. From a point of view of the geochemistry of the granites under investigation, a comparison of the laws of distribution of the major elements in the 4 ranges shows up a convergence of average composition which was not anticipated by geological and petrographic considerations alone. The statistical and geochemical distribution laws of the total uranium as a function of the petrochemical variations are established. A study of the chemical forms of uranium in the rocks has drawn an attention to the qualitative and quantitative importance of the fraction of this uranium soluble in dilute acids. We have therefore reconsidered on the one hand, the laws of distribution of the insoluble uranium, which represents essentially the uranium fixed in crystalline structures (zircon, allanite...), and we have justified on the other hand the interest presented by the soluble uranium: this, although more complex in character, presents a geochemical unity in post magmatic phenomena which makes possible to find a genetic connection between the uraniferous deposits and the intrusive massifs. Finally we have given a plan of the geochemical cycle of uranium, in which we hope to have provided some more accurate data on the igneous phase. (author) [fr

  16. Graphene as a local probe to investigate near-field properties of plasmonic nanostructures

    Science.gov (United States)

    Wasserroth, Sören; Bisswanger, Timo; Mueller, Niclas S.; Kusch, Patryk; Heeg, Sebastian; Clark, Nick; Schedin, Fredrik; Gorbachev, Roman; Reich, Stephanie

    2018-04-01

    Light interacting with metallic nanoparticles creates a strongly localized near-field around the particle that enhances inelastic light scattering by several orders of magnitude. Surface-enhanced Raman scattering describes the enhancement of the Raman intensity by plasmonic nanoparticles. We present an extensive Raman characterization of a plasmonic gold nanodimer covered with graphene. Its two-dimensional nature and energy-independent optical properties make graphene an excellent material for investigating local electromagnetic near-fields. We show the localization of the near-field of the plasmonic dimer by spatial Raman measurements. Energy- and polarization-dependent measurements reveal the local near-field resonance of the plasmonic system. To investigate the far-field resonance we perform dark-field spectroscopy and find that near-field and far-field resonance energies differ by 170 meV, much more than expected from the model of a damped oscillator (40 meV).

  17. Efficient Calculation of Near Fields in the FDTD Method

    DEFF Research Database (Denmark)

    Franek, Ondrej

    2011-01-01

    When calculating frequency-domain near fields by the FDTD method, almost 50 % reduction in memory and CPU operations can be achieved if only E-fields are stored during the main time-stepping loop and H-fields computed later. An improved method of obtaining the H-fields from Faraday's Law is prese...

  18. Prediction of Near-Field Wave Attenuation Due to a Spherical Blast Source

    Science.gov (United States)

    Ahn, Jae-Kwang; Park, Duhee

    2017-11-01

    Empirical and theoretical far-field attenuation relationships, which do not capture the near-field response, are most often used to predict the peak amplitude of blast wave. Jiang et al. (Vibration due to a buried explosive source. PhD Thesis, Curtin University, Western Australian School of Mines, 1993) present rigorous wave equations that simulates the near-field attenuation to a spherical blast source in damped and undamped media. However, the effect of loading frequency and velocity of the media have not yet been investigated. We perform a suite of axisymmetric, dynamic finite difference analyses to simulate the propagation of stress waves induced by spherical blast source and to quantify the near-field attenuation. A broad range of loading frequencies, wave velocities, and damping ratios are used in the simulations. The near-field effect is revealed to be proportional to the rise time of the impulse load and wave velocity. We propose an empirical additive function to the theoretical far-field attenuation curve to predict the near-field range and attenuation. The proposed curve is validated against measurements recorded in a test blast.

  19. Superconducting Material - A study on the near field of a superconducting antenna

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Soon Chil; Lee, Seung Chul; Doe, Joong Hoe; Hoe, Mi Ra [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1996-07-01

    The pulse spectroscopy in combination with piezoelectric resonance makes an ideal non-disturbing tool for the measurement of electric field near an antenna. This new field sensing technique was used to investigate the field of a ring antenna the near field of which is widely used such as the plasma generation and NMR. The superconducting wire also have the dominant capacitive AC field in near regions, meaning that the net charge on the ring surface is not due to the ohm`s law as in DC. 23 refs., 8 figs. (author)

  20. The near coastal environment monitored from space

    International Nuclear Information System (INIS)

    Szekielda, K.H.

    1977-01-01

    The optical information required for monitoring the marine environment from space is discussed and applied for the near coastal area. By categorizing coastal features it is possible to recognize coastal regions to a high degree and to indentify water masses derived from land sources and sewage dumping sites. It is concluded that monitoring from space can be used as a tool in environmental planning. (orig.) [de

  1. Near-Field Thermal Radiation for Solar Thermophotovoltaics and High Temperature Thermal Logic and Memory Applications

    Science.gov (United States)

    Elzouka, Mahmoud

    This dissertation investigates Near-Field Thermal Radiation (NFTR) applied to MEMS-based concentrated solar thermophotovoltaics (STPV) energy conversion and thermal memory and logics. NFTR is the exchange of thermal radiation energy at nano/microscale; when separation between the hot and cold objects is less than dominant radiation wavelength (˜1 mum). NFTR is particularly of interest to the above applications due to its high rate of energy transfer, exceeding the blackbody limit by orders of magnitude, and its strong dependence on separation gap size, surface nano/microstructure and material properties. Concentrated STPV system converts solar radiation to electricity using heat as an intermediary through a thermally coupled absorber/emitter, which causes STPV to have one of the highest solar-to-electricity conversion efficiency limits (85.4%). Modeling of a near-field concentrated STPV microsystem is carried out to investigate the use of STPV based solid-state energy conversion as high power density MEMS power generator. Numerical results for In 0.18Ga0.82Sb PV cell illuminated with tungsten emitter showed significant enhancement in energy transfer, resulting in output power densities as high as 60 W/cm2; 30 times higher than the equivalent far-field power density. On thermal computing, this dissertation demonstrates near-field heat transfer enabled high temperature NanoThermoMechanical memory and logics. Unlike electronics, NanoThermoMechanical memory and logic devices use heat instead of electricity to record and process data; hence they can operate in harsh environments where electronics typically fail. NanoThermoMechanical devices achieve memory and thermal rectification functions through the coupling of near-field thermal radiation and thermal expansion in microstructures, resulting in nonlinear heat transfer between two temperature terminals. Numerical modeling of a conceptual NanoThermoMechanical is carried out; results include the dynamic response under

  2. THz near-field imaging of biological tissues employing synchrotron radiation

    International Nuclear Information System (INIS)

    Schade, Ulrich; Holldack, Karsten; Martin, Michael C.; Fried, Daniel

    2004-01-01

    Terahertz scanning near-field infrared microscopy (SNIM) below 1 THz is demonstrated. The near-field technique benefits from the broadband and highly brilliant coherent synchrotron radiation (CSR) from an electron storage ring and from a detection method based on locking onto the intrinsic time structure of the synchrotron radiation. The scanning microscope utilizes conical wave guides as near-field probes with apertures smaller than the wavelength. Different cone approaches have been investigated to obtain maximum transmittance. Together with a Martin-Puplett spectrometer the set-up enables spectroscopic mapping of the transmittance of samples well below the diffraction limit. Spatial resolution down to about lambda/40 at 2 wavenumbers (0.06 THz) is derived from the transmittance spectra of the near-field probes. The potential of the technique is exemplified by imaging biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 mu-m at about 12 wave numbers (0.36 THz). The THz near-field images reveal distinct structural differences of leaves from different plants investigated. The technique presented also allows spectral imaging of bulky organic tissues. Human teeth samples of various thicknesses have been imaged between 2 and 20 wavenumbers (between 0.06and 0.6 THz). Regions of enamel and dentin within tooth samples are spatially and spectrally resolved, and buried caries lesions are imaged through both the outer enamel and into the underlying dentin

  3. Strain-induced modulation of near-field radiative transfer.

    Science.gov (United States)

    Ghanekar, Alok; Ricci, Matthew; Tian, Yanpei; Gregory, Otto; Zheng, Yi

    2018-06-11

    In this theoretical study, we present a near-field thermal modulator that exhibits change in radiative heat transfer when subjected to mechanical stress/strain. The device has two terminals at different temperatures separated by vacuum: one fixed and one stretchable. The stretchable side contains one-dimensional grating. When subjected to mechanical strain, the effective optical properties of the stretchable side are affected upon deformation of the grating. This results in modulation of surface waves across the interfaces influencing near-field radiative heat transfer. We show that for a separation of 100 nm, it is possible to achieve 25% change in radiative heat transfer for a strain of 10%.

  4. Geochemistry of natural technetium and plutonium

    International Nuclear Information System (INIS)

    Curtis, D.B.; Cappis, J.H.; Perrin, R.E.; Rokop, D.J.

    1987-01-01

    Technetium and plutonium in unprocessed nuclear reactor wastes are major concerns with regard to their containment in the geologic environment. Both nuclides have long half-lives; therefore, they will exist long after engineered barriers can be considered reliable. Consequently, strategies for the containment of these two elements depend on their retention in the geologic barrier until they have decayed to innocuous levels. Because these are the rarest elements in nature, there have been few direct observations of their geochemical behavior; predictions concerning their fate in the repository are based on properties that can be observed in the laboratory. The authors are attempting to complement the laboratory work by studying the geochemistry of natural plutonium and technetium. Ratios of anthropogenic to naturally occurring isotopes are discussed

  5. Dynamically important magnetic fields near accreting supermassive black holes.

    Science.gov (United States)

    Zamaninasab, M; Clausen-Brown, E; Savolainen, T; Tchekhovskoy, A

    2014-06-05

    Accreting supermassive black holes at the centres of active galaxies often produce 'jets'--collimated bipolar outflows of relativistic particles. Magnetic fields probably play a critical role in jet formation and in accretion disk physics. A dynamically important magnetic field was recently found near the Galactic Centre black hole. If this is common and if the field continues to near the black hole event horizon, disk structures will be affected, invalidating assumptions made in standard models. Here we report that jet magnetic field and accretion disk luminosity are tightly correlated over seven orders of magnitude for a sample of 76 radio-loud active galaxies. We conclude that the jet-launching regions of these radio-loud galaxies are threaded by dynamically important fields, which will affect the disk properties. These fields obstruct gas infall, compress the accretion disk vertically, slow down the disk rotation by carrying away its angular momentum in an outflow and determine the directionality of jets.

  6. High Frequency Near-Field Ground Motion Excited by Strike-Slip Step Overs

    Science.gov (United States)

    Hu, Feng; Wen, Jian; Chen, Xiaofei

    2018-03-01

    We performed dynamic rupture simulations on step overs with 1-2 km step widths and present their corresponding horizontal peak ground velocity distributions in the near field within different frequency ranges. The rupture speeds on fault segments are determinant in controlling the near-field ground motion. A Mach wave impact area at the free surface, which can be inferred from the distribution of the ratio of the maximum fault-strike particle velocity to the maximum fault-normal particle velocity, is generated in the near field with sustained supershear ruptures on fault segments, and the Mach wave impact area cannot be detected with unsustained supershear ruptures alone. Sub-Rayleigh ruptures produce stronger ground motions beyond the end of fault segments. The existence of a low-velocity layer close to the free surface generates large amounts of high-frequency seismic radiation at step over discontinuities. For near-vertical step overs, normal stress perturbations on the primary fault caused by dipping structures affect the rupture speed transition, which further determines the distribution of the near-field ground motion. The presence of an extensional linking fault enhances the near-field ground motion in the extensional regime. This work helps us understand the characteristics of high-frequency seismic radiation in the vicinities of step overs and provides useful insights for interpreting the rupture speed distributions derived from the characteristics of near-field ground motion.

  7. Superresolution Near-field Imaging with Surface Waves

    KAUST Repository

    Fu, Lei; Liu, Zhaolun; Schuster, Gerard T.

    2017-01-01

    We present the theory for near-field superresolution imaging with surface waves and time reverse mirrors (TRMs). Theoretical formulas and numerical results show that applying the TRM operation to surface waves in an elastic half-space can achieve

  8. Chemical and microbiological effects in the near field: current status

    International Nuclear Information System (INIS)

    Ewart, F.T.; Pugh, S.Y.R.; Wisbey, S.J.; Woodwark, D.R.

    1988-12-01

    The radionuclide inventory of a radioactive waste repository, influenced by the chemical conditions in the near-field, determines the source term for radionuclides entering the geosphere. The research described in this report is focussed on providing the information necessary to quantify this source term. The processes which interact to determine near field behaviour over a long period of time are complex and a simplified representation is required for radiological assessment modelling. The assumptions made in formulating the near field assessment methodology are discussed and justified in this report. The techniques for acquiring the necessary large body of data for a wide range of relevant radionuclides are also described and the values used in the CASCADE I exercise are given. (author)

  9. Simultaneous near field imaging of electric and magnetic field in photonic crystal nanocavities

    NARCIS (Netherlands)

    Vignolini, S.; Intonti, F.; Riboli, F.; Wiersma, D.S.; Balet, L.P.; Li, L.H.; Francardi, M.; Gerardino, A.; Fiore, A.; Gurioli, M.

    2012-01-01

    The insertion of a metal-coated tip on the surface of a photonic crystal microcavity is used for simultaneous near field imaging of electric and magnetic fields in photonic crystal nanocavities, via the radiative emission of embedded semiconductor quantum dots (QD). The photoluminescence intensity

  10. Long-term CO2 injection and its impact on near-surface soil microbiology.

    Science.gov (United States)

    Gwosdz, Simone; West, Julia M; Jones, David; Rakoczy, Jana; Green, Kay; Barlow, Tom; Blöthe, Marco; Smith, Karon; Steven, Michael; Krüger, Martin

    2016-12-01

    Impacts of long-term CO 2 exposure on environmental processes and microbial populations of near-surface soils are poorly understood. This near-surface long-term CO 2 injection study demonstrated that soil microbiology and geochemistry is influenced more by seasonal parameters than elevated CO 2 Soil samples were taken during a 3-year field experiment including sampling campaigns before, during and after 24 months of continuous CO 2 injection. CO 2 concentrations within CO 2 -injected plots increased up to 23% during the injection period. No CO 2 impacts on geochemistry were detected over time. In addition, CO 2 -exposed samples did not show significant changes in microbial CO 2 and CH 4 turnover rates compared to reference samples. Likewise, no significant CO 2 -induced variations were detected for the abundance of Bacteria, Archaea (16S rDNA) and gene copy numbers of the mcrA gene, Crenarchaeota and amoA gene. The majority (75%-95%) of the bacterial sequences were assigned to five phyla: Firmicutes, Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes The majority of the archaeal sequences (85%-100%) were assigned to the thaumarchaeotal cluster I.1b (soil group). Univariate and multivariate statistical as well as principal component analyses showed no significant CO 2 -induced variation. Instead, seasonal impacts especially temperature and precipitation were detected. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Principles of planar near-field antenna measurements

    CERN Document Server

    Gregson, Stuart; Parini, Clive

    2007-01-01

    This single volume provides a comprehensive introduction and explanation of both the theory and practice of 'Planar Near-Field Antenna Measurement' from its basic postulates and assumptions, to the intricacies of its deployment in complex and demanding measurement scenarios.

  12. Geochemical evolution of the L/ILW near-field

    International Nuclear Information System (INIS)

    Kosakowski, G.; Berner, U.; Wieland, E.; Glaus, M.; Degueldre, C.

    2014-10-01

    The deep geological repository for low- and intermediate-level radioactive waste (L/ILW) contains large amounts of cement based materials used for waste conditioning, tunnel support and the backfill of cavities. The waste inventory is composed of a wide range of organic and inorganic materials. This study describes the spatial and temporal geochemical evolution of the cementitious near-field, and the interactions with the technical barriers and the surrounding host rock. This evolution is governed by several coupled processes, an important one being the development of saturation by groundwater ingress from the host rock. Saturation of the near-field is controlled by the inflow of water from the host rock, by the transport of dissolved gases from the near-field into the host rock and in the engineered gas transport system, and by the transport of humidity in the gas phase. The production of gas by anoxic corrosion of metals and by microbial degradation of organic wastes consumes water. The mineral reactions which give rise to concrete degradation, such as carbonation or alkali-silica-aggregate reactions may also consume or produce water. The first phase of cementitious near-field degradation, which persists only for a short period of time, is related to the hydration of cement minerals. The pore water has a pH of 13 or even higher because of the high content of dissolved alkali hydroxides. A constant pH of 12.5 determines the second phase of the cement degradation. The alkali concentration is reduced by mineral reactions and/or solute transport. This phase persists for a long time. In the third phase the portlandite is completely dissolved due to the reaction with silicates/aluminates present in the near-field and carbonate in the groundwater of the host rock or associated with reactive waste materials. The pore water is in equilibrium with calcium-silicate-hydrates (C-S-H) which gives rise to a pH value near 11 or lower. The Ca/Si ratio of C-S-H changes towards

  13. Geochemical evolution of the L/ILW near-field

    Energy Technology Data Exchange (ETDEWEB)

    Kosakowski, G.; Berner, U.; Wieland, E.; Glaus, M.; Degueldre, C.

    2014-10-15

    The deep geological repository for low- and intermediate-level radioactive waste (L/ILW) contains large amounts of cement based materials used for waste conditioning, tunnel support and the backfill of cavities. The waste inventory is composed of a wide range of organic and inorganic materials. This study describes the spatial and temporal geochemical evolution of the cementitious near-field, and the interactions with the technical barriers and the surrounding host rock. This evolution is governed by several coupled processes, an important one being the development of saturation by groundwater ingress from the host rock. Saturation of the near-field is controlled by the inflow of water from the host rock, by the transport of dissolved gases from the near-field into the host rock and in the engineered gas transport system, and by the transport of humidity in the gas phase. The production of gas by anoxic corrosion of metals and by microbial degradation of organic wastes consumes water. The mineral reactions which give rise to concrete degradation, such as carbonation or alkali-silica-aggregate reactions may also consume or produce water. The first phase of cementitious near-field degradation, which persists only for a short period of time, is related to the hydration of cement minerals. The pore water has a pH of 13 or even higher because of the high content of dissolved alkali hydroxides. A constant pH of 12.5 determines the second phase of the cement degradation. The alkali concentration is reduced by mineral reactions and/or solute transport. This phase persists for a long time. In the third phase the portlandite is completely dissolved due to the reaction with silicates/aluminates present in the near-field and carbonate in the groundwater of the host rock or associated with reactive waste materials. The pore water is in equilibrium with calcium-silicate-hydrates (C-S-H) which gives rise to a pH value near 11 or lower. The Ca/Si ratio of C-S-H changes towards

  14. Phased Array Excitations For Efficient Near Field Wireless Power Transmission

    Science.gov (United States)

    2016-09-01

    channeled to the battery or power plant. Figure 2. WPT System Block Diagram for Battery Charging. Source : [2]. Wireless power transfer has gained...EXCITATIONS FOR EFFICIENT NEAR-FIELD WIRELESS POWER TRANSMISSION by Sean X. Hong September 2016 Thesis Advisor: David Jenn Second Reader...TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE PHASED ARRAY EXCITATIONS FOR EFFICIENT NEAR-FIELD WIRELESS POWER TRANSMISSION 5

  15. Molecular environmental geochemistry

    Science.gov (United States)

    O'Day, Peggy A.

    1999-05-01

    The chemistry, mobility, and bioavailability of contaminant species in the natural environment are controlled by reactions that occur in and among solid, aqueous, and gas phases. These reactions are varied and complex, involving changes in chemical form and mass transfer among inorganic, organic, and biochemical species. The field of molecular environmental geochemistry seeks to apply spectroscopic and microscopic probes to the mechanistic understanding of environmentally relevant chemical processes, particularly those involving contaminants and Earth materials. In general, empirical geochemical models have been shown to lack uniqueness and adequate predictive capability, even in relatively simple systems. Molecular geochemical tools, when coupled with macroscopic measurements, can provide the level of chemical detail required for the credible extrapolation of contaminant reactivity and bioavailability over ranges of temperature, pressure, and composition. This review focuses on recent advances in the understanding of molecular chemistry and reaction mechanisms at mineral surfaces and mineral-fluid interfaces spurred by the application of new spectroscopies and microscopies. These methods, such as synchrotron X-ray absorption and scattering techniques, vibrational and resonance spectroscopies, and scanning probe microscopies, provide direct chemical information that can elucidate molecular mechanisms, including element speciation, ligand coordination and oxidation state, structural arrangement and crystallinity on different scales, and physical morphology and topography of surfaces. Nonvacuum techniques that allow examination of reactions in situ (i.e., with water or fluids present) and in real time provide direct links between molecular structure and reactivity and measurements of kinetic rates or thermodynamic properties. Applications of these diverse probes to laboratory model systems have provided fundamental insight into inorganic and organic reactions at

  16. SHELL ISOTOPE GEOCHEMISTRY

    African Journals Online (AJOL)

    ABSTRACT: The land snail Limicolaria kambeul chudeaui Germain was collected ... Key words/phrases: Ethiopia, isotope geochemistry, Lake Tilo, Limicolaria .... 1984), (c) 6'80 values of precipitation at Addis Ababa, with i 1 S.D. bars for the .... (breakfast cereal), deionised water and cuttlefish bone, the carbon and oxygen.

  17. Nanohybrids Near-Field Optical Microscopy: From Image Shift to Biosensor Application

    Directory of Open Access Journals (Sweden)

    Nayla El-Kork

    2016-01-01

    Full Text Available Near-Field Optical Microscopy is a valuable tool for the optical and topographic study of objects at a nanometric scale. Nanoparticles constitute important candidates for such type of investigations, as they bear an important weight for medical, biomedical, and biosensing applications. One, however, has to be careful as artifacts can be easily reproduced. In this study, we examined hybrid nanoparticles (or nanohybrids in the near-field, while in solution and attached to gold nanoplots. We found out that they can be used for wavelength modulable near-field biosensors within conditions of artifact free imaging. In detail, we refer to the use of topographic/optical image shift and the imaging of Local Surface Plasmon hot spots to validate the genuineness of the obtained images. In summary, this study demonstrates a new way of using simple easily achievable comparative methods to prove the authenticity of near-field images and presents nanohybrid biosensors as an application.

  18. Near-field photometry for organic light-emitting diodes

    Science.gov (United States)

    Li, Rui; Harikumar, Krishnan; Isphording, Alexandar; Venkataramanan, Venkat

    2013-03-01

    Organic Light Emitting Diode (OLED) technology is rapidly maturing to be ready for next generation of light source for general lighting. The current standard test methods for solid state lighting have evolved for semiconductor sources, with point-like emission characteristics. However, OLED devices are extended surface emitters, where spatial uniformity and angular variation of brightness and colour are important. This necessitates advanced test methods to obtain meaningful data for fundamental understanding, lighting product development and deployment. In this work, a near field imaging goniophotometer was used to characterize lighting-class white OLED devices, where luminance and colour information of the pixels on the light sources were measured at a near field distance for various angles. Analysis was performed to obtain angle dependent luminous intensity, CIE chromaticity coordinates and correlated colour temperature (CCT) in the far field. Furthermore, a complete ray set with chromaticity information was generated, so that illuminance at any distance and angle from the light source can be determined. The generated ray set is needed for optical modeling and design of OLED luminaires. Our results show that luminance non-uniformity could potentially affect the luminaire aesthetics and CCT can vary with angle by more than 2000K. This leads to the same source being perceived as warm or cool depending on the viewing angle. As OLEDs are becoming commercially available, this could be a major challenge for lighting designers. Near field measurement can provide detailed specifications and quantitative comparison between OLED products for performance improvement.

  19. Near-field interference for the unidirectional excitation of electromagnetic guided modes.

    Science.gov (United States)

    Rodríguez-Fortuño, Francisco J; Marino, Giuseppe; Ginzburg, Pavel; O'Connor, Daniel; Martínez, Alejandro; Wurtz, Gregory A; Zayats, Anatoly V

    2013-04-19

    Wave interference is a fundamental manifestation of the superposition principle with numerous applications. Although in conventional optics, interference occurs between waves undergoing different phase advances during propagation, we show that the vectorial structure of the near field of an emitter is essential for controlling its radiation as it interferes with itself on interaction with a mediating object. We demonstrate that the near-field interference of a circularly polarized dipole results in the unidirectional excitation of guided electromagnetic modes in the near field, with no preferred far-field radiation direction. By mimicking the dipole with a single illuminated slit in a gold film, we measured unidirectional surface-plasmon excitation in a spatially symmetric structure. The surface wave direction is switchable with the polarization.

  20. High-Accuracy Spherical Near-Field Measurements for Satellite Antenna Testing

    DEFF Research Database (Denmark)

    Breinbjerg, Olav

    2017-01-01

    The spherical near-field antenna measurement technique is unique in combining several distinct advantages and it generally constitutes the most accurate technique for experimental characterization of radiation from antennas. From the outset in 1970, spherical near-field antenna measurements have...... matured into a well-established technique that is widely used for testing antennas for many wireless applications. In particular, for high-accuracy applications, such as remote sensing satellite missions in ESA's Earth Observation Programme with uncertainty requirements at the level of 0.05dB - 0.10d......B, the spherical near-field antenna measurement technique is generally superior. This paper addresses the means to achieving high measurement accuracy; these include the measurement technique per se, its implementation in terms of proper measurement procedures, the use of uncertainty estimates, as well as facility...

  1. Technical Work Plan for: Near Field Environment: Engineered Barrier System: Radionuclide Transport Abstraction Model Report

    International Nuclear Information System (INIS)

    J.D. Schreiber

    2006-01-01

    This technical work plan (TWP) describes work activities to be performed by the Near-Field Environment Team. The objective of the work scope covered by this TWP is to generate Revision 03 of EBS Radionuclide Transport Abstraction, referred to herein as the radionuclide transport abstraction (RTA) report. The RTA report is being revised primarily to address condition reports (CRs), to address issues identified by the Independent Validation Review Team (IVRT), to address the potential impact of transport, aging, and disposal (TAD) canister design on transport models, and to ensure integration with other models that are closely associated with the RTA report and being developed or revised in other analysis/model reports in response to IVRT comments. The RTA report will be developed in accordance with the most current version of LP-SIII.10Q-BSC and will reflect current administrative procedures (LP-3.15Q-BSC, ''Managing Technical Product Inputs''; LP-SIII.2Q-BSC, ''Qualification of Unqualified Data''; etc.), and will develop related Document Input Reference System (DIRS) reports and data qualifications as applicable in accordance with prevailing procedures. The RTA report consists of three models: the engineered barrier system (EBS) flow model, the EBS transport model, and the EBS-unsaturated zone (UZ) interface model. The flux-splitting submodel in the EBS flow model will change, so the EBS flow model will be validated again. The EBS transport model and validation of the model will be substantially revised in Revision 03 of the RTA report, which is the main subject of this TWP. The EBS-UZ interface model may be changed in Revision 03 of the RTA report due to changes in the conceptualization of the UZ transport abstraction model (a particle tracker transport model based on the discrete fracture transfer function will be used instead of the dual-continuum transport model previously used). Validation of the EBS-UZ interface model will be revised to be consistent with

  2. Optical near-field lithography on hydrogen-passivated silicon surfaces

    DEFF Research Database (Denmark)

    Madsen, Steen; Müllenborn, Matthias; Birkelund, Karen

    1996-01-01

    by the optical near field, were observed after etching in potassium hydroxide. The uncoated fibers can also induce oxidation without light exposure, in a manner similar to an atomic force microscope, and linewidths of 50 nm have been achieved this way. (C) 1996 American Institute of Physics.......We report on a novel lithography technique for patterning of hydrogen-passivated amorphous silicon surfaces. A reflection mode scanning near-field optical microscope with uncoated fiber probes has been used to locally oxidize a thin amorphous silicon layer. Lines of 110 nm in width, induced...

  3. Extracting 220 Hz information from 55 Hz field data by near-field superresolution imaging

    KAUST Repository

    Dutta, Gaurav

    2016-05-31

    Field experiments are used to unequivocally demonstrate seismic superresolution imaging of subwavelength objects in the near-field region of the source. The field test is for a conventional hammer source striking a metal plate near subwavelength scatterers and the seismic data are recorded by vertical-component geophones in the far-field locations of the sources. Time-reversal mirrors (TRMs) are then used to refocus the scattered energy with subwavelength resolution to the position of the original source. A spatial resolution of lambda/10, where lambda is the dominant wavelength associated with the data, is seen in the field tests that exceeds the Abbe resolution limit of lambda/2.

  4. Extracting 220 Hz information from 55 Hz field data by near-field superresolution imaging

    KAUST Repository

    Dutta, Gaurav; AlTheyab, Abdullah; Tarhini, Ahmad; Hanafy, Sherif; Schuster, Gerard T.

    2016-01-01

    Field experiments are used to unequivocally demonstrate seismic superresolution imaging of subwavelength objects in the near-field region of the source. The field test is for a conventional hammer source striking a metal plate near subwavelength scatterers and the seismic data are recorded by vertical-component geophones in the far-field locations of the sources. Time-reversal mirrors (TRMs) are then used to refocus the scattered energy with subwavelength resolution to the position of the original source. A spatial resolution of lambda/10, where lambda is the dominant wavelength associated with the data, is seen in the field tests that exceeds the Abbe resolution limit of lambda/2.

  5. Control strategies for active noise barriers using near-field error sensing

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    In this paper active noise control strategies for noise barriers are presented which are based on the use of sensors near the noise barrier. Virtual error signals are derived from these near-field sensor signals such that reductions of the far-field sound pressure are obtained with the active

  6. Groundwater denitrification in two agricultural river catchments: influence of hydro-geological setting and aquifer geochemistry

    Science.gov (United States)

    McAleer, Eoin; Mellander, Per-Erik; Coxon, Catherine; Richards, Karl G.; Jahangir, Mohammad M. R.

    2015-04-01

    Identifying subsurface environments with a natural capacity for denitrification is important for improving agricultural management. At the catchment scale, a complex hierarchy of landscape, hydro-geological and physico-chemical characteristics combine to affect the distribution of groundwater nitrate (NO3-). This study was conducted along four instrumented hillslopes in two ca. 10km2 agricultural river catchments in Ireland, one dominated by arable and one by grassland agriculture. Both catchments are characterised by well drained soils, but have differing aquifer characteristics. The arable catchment is underlain by weathered Ordovician slate bedrock which is extensively fractured with depth. The grassland catchment is characterised by Devonian sandstone bedrock, exhibiting both lateral (from upslope to near stream) and vertical variations in permeability along each hillslope. The capacity for groundwater denitrification was assessed by examining the concentration and distribution patterns of N species (total nitrogen, nitrate, nitrite, ammonium), dissolved organic carbon (DOC), dissolved oxygen (DO) and redox potential (Eh) in monthly samples from shallow and deep groundwater piezometers (n=37). Additionally, the gaseous products of denitrification: nitrous oxide (N2O) and excess dinitrogen (excess N2) were measured seasonally using gas chromatography and membrane inlet mass spectroscopy, respectively. The slate catchment was characterised by uniformity, both laterally and vertically, in aquifer geochemistry and gaseous denitrification products. The four year spatial mean groundwater NO3--N concentration was 6.89 mg/l and exhibited low spatial and temporal variability (temporal SD: 1.19 mg/l, spatial SD: 1.185 mg/l). Elevated DO concentrations (mean: 9.75 mg/l) and positive Eh (mean: +176.5mV) at all sample horizons indicated a setting with little denitrification potential. This non-reducing environment was reflected in a low accumulation of denitrification

  7. A review of sorption of radionuclides under the near- and far-field conditions of an underground radioactive waste repository. Pt. 3

    International Nuclear Information System (INIS)

    Berry, J.A.

    1992-01-01

    This report summarises work funded by the Department of the Environment and UK Nirex Ltd in the area of sorption of radionuclides under the near-field and far-field conditions pertaining to the underground disposal of radioactive waste in the UK that was presented and discussed in Part I. The report also summarises comparable research undertaken overseas (presented in Part II). (author)

  8. Light distribution analysis of optical fibre probe-based near-field optical tweezers using FDTD

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B H; Yang, L J; Wang, Y [School of Mechanical and Electrical Engineering, Harbin Institute of Technology, Heilongjiang, Harbin, 150001 (China)], E-mail: richelaw@163.com

    2009-09-01

    Optical fibre probe-based near-field optical tweezers overcomes the diffraction limit of conventional optical tweezers, utilizing strong mechanical forces and torque associated with highly enhanced electric fields to trap and manipulate nano-scale particles. Near-field evanescent wave generated at optical fibre probe decays rapidly with the distance that results a significant reduced trapping volume, thus it is necessary to analyze the near-field distribution of optical fibre probe. The finite difference time domain (FDTD) method is applied to characterize the near-field distribution of optical fibre probe. In terms of the distribution patterns, depolarization and polarization, the near-field distributions in longitudinal sections and cross-sections of tapered metal-coated optical fibre probe are calculated. The calculation results reveal that the incident polarized wave becomes depolarized after exiting from the nano-scale aperture of probe. The near-field distribution of the probe is unsymmetrical, and the near-field distribution in the cross-section vertical to the incident polarized wave is different from that in the cross-section parallel to the incident polarized wave. Moreover, the polarization of incident wave has a great impact on the light intensity distribution.

  9. A quasi-hemispheric model of the Hermean's magnetic field

    Science.gov (United States)

    Thebault, E.; Oliveira, J.; Langlais, B.; Amit, H.

    2015-10-01

    We analyse and process magnetic field measurements provided by the MErcury Surface, Space ENvironment, Geochemistry, and Ranging (MESSENGER) mission. The vect or magnetic field measurements are modelled with a dedicated regional scheme expanded in space and in time. Compared to the widely used global Spherical Harmonics (SH), the regional approach is particularly well suited because the partial and quasi hemispheric distribution of the MESSENGER data represents no major numerical difficulty. We confirm that the internal magnetic field of Mercury is mostly axisymmetric with a magnetic equator shifted northward. However, we also observe a time dependency in the model that is at present hardly explained only by time variations of the external magnetic fields. We present the major spatial and temporal structures shown by the regional model.

  10. Uranium project. Geochemistry prospection[Study of Uranium geochemical prospection in Uruguay]; Proyecto Uranio. Prospeccion geoquimica

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, J

    1983-07-01

    Geochemistry studies the distribution of the chemicals elements in the terrestrial crust and its ways to migrate. The terminology used in this report is the following one: 1) Principles of the prospection geochemistry 2) Stages of the prospection geochemistry 3)utility of the prospection geochemistry 4) geochemistry of uranium 5) procedures used within the framework of uranium project 6) Average available 7) Selection of the zones of prospection geochemistry 8) Stages of the prospection, Sample preparation and analisis 9) Presentation of the results.

  11. Room-temperature near-field reflection spectrocopy of semiconductor nanostructures

    DEFF Research Database (Denmark)

    Langbein, Wolfgang; Hvam, Jørn Märcher; Madsen, Steen

    1999-01-01

    We investigate the properties of near-field reflection spectroscopy in different polarization and detection modes using uncoated fiber probes. The results show, that cross-polarized detection suppresses to a large extent far-field contributions. Using the fiber dithering as a modulation source fo...

  12. Mean-field theory of anyons near Bose statistics

    International Nuclear Information System (INIS)

    McCabe, J.; MacKenzie, R.

    1992-01-01

    The validity of a mean-field approximation for a boson-based free anyon gas near Bose statistics is shown. The magnetic properties of the system is discussed in the approximation that the statistical magnetic field is uniform. It is proved that the anyon gas does not exhibit a Meissner effect in the domain of validity the approximation. (K.A.) 7 refs

  13. Near-field heat transfer between graphene/hBN multilayers

    Science.gov (United States)

    Zhao, Bo; Guizal, Brahim; Zhang, Zhuomin M.; Fan, Shanhui; Antezza, Mauro

    2017-06-01

    We study the radiative heat transfer between multilayer structures made by a periodic repetition of a graphene sheet and a hexagonal boron nitride (hBN) slab. Surface plasmons in a monolayer graphene can couple with hyperbolic phonon polaritons in a single hBN film to form hybrid polaritons that can assist photon tunneling. For periodic multilayer graphene/hBN structures, the stacked metallic/dielectric array can give rise to a further effective hyperbolic behavior, in addition to the intrinsic natural hyperbolic behavior of hBN. The effective hyperbolicity can enable more hyperbolic polaritons that enhance the photon tunneling and hence the near-field heat transfer. However, the hybrid polaritons on the surface, i.e., surface plasmon-phonon polaritons, dominate the near-field heat transfer between multilayer structures when the topmost layer is graphene. The effective hyperbolic regions can be well predicted by the effective medium theory (EMT), thought EMT fails to capture the hybrid surface polaritons and results in a heat transfer rate much lower compared to the exact calculation. The chemical potential of the graphene sheets can be tuned through electrical gating and results in an additional modulation of the heat transfer. We found that the near-field heat transfer between multilayer structures does not increase monotonously with the number of layers in the stack, which provides a way to control the heat transfer rate by the number of graphene layers in the multilayer structure. The results may benefit the applications of near-field energy harvesting and radiative cooling based on hybrid polaritons in two-dimensional materials.

  14. Near-Field Antenna Measurements Using Photonic Sensor of Mach-Zehnder Interferometer

    Directory of Open Access Journals (Sweden)

    Masanobu Hirose

    2012-01-01

    Full Text Available We have been developing a photonic sensor system to measure the electric near-field distribution at a distance shorter than one wavelength from the aperture of an antenna. The photonic sensor is a type of Mach-Zehnder interferometer and consists of an array antenna of 2.4 mm height and 2 mm width on a LiNbO3 substrate (0.5 mm thickness, 8 mm length, and 3 mm width supported by a glass pipe. The photonic sensor can be considered to be a receiving infinitesimal dipole antenna that is a tiny metallic part printed on a small dielectric plate at microwave frequency. Those physical and electrical features make the photonic sensor attractive when used as a probe for near-field antenna measurements. We have demonstrated that the system can be applied to planar, spherical, and cylindrical near-field antenna measurements without any probe compensation approximately below 10 GHz. We show the theories and the measurements using the photonic sensor in the three near-field antenna measurement methods.

  15. Plasmonic Devices for Near and Far-Field Applications

    KAUST Repository

    Alrasheed, Salma

    2017-11-30

    Plasmonics is an important branch of nanophotonics and is the study of the interaction of electromagnetic fields with the free electrons in a metal at metallic/dielectric interfaces or in small metallic nanostructures. The electric component of an exciting electromagnetic field can induce collective electron oscillations known as surface plasmons. Such oscillations lead to the localization of the fields that can be at sub-wavelength scale and to its significant enhancement relative to the excitation fields. These two characteristics of localization and enhancement are the main components that allow for the guiding and manipulation of light beyond the diffraction limit. This thesis focuses on developing plasmonic devices for near and far-field applications. In the first part of the thesis, we demonstrate the detection of single point mutation in peptides from multicomponent mixtures for early breast cancer detection using selfsimilar chain (SCC) plasmonic devices that show high field enhancement and localization. In the second part of this work, we investigate the anomalous reflection of light for TM polarization for normal and oblique incidence in the visible regime. We propose gradient phase gap surface plasmon (GSP) metasurfaces that exhibit high conversion efficiency (up to ∼97% of total reflected light) to the anomalous reflection angle for blue, green and red wavelengths at normal and oblique incidence. In the third part of the thesis, we present a theoretical approach to narrow the plasmon linewidth and enhance the near-field intensity at a plasmonic dimer gap (hot spot) through coupling the electric localized surface plasmon (LSP) resonance of a silver hemispherical dimer with the resonant modes of a Fabry-Perot (FP) cavity. In the fourth part of this work, we demonstrate numerically bright color pixels that are highly polarized and broadly tuned using periodic arrays of metal nanosphere dimers on a glass substrate. In the fifth and final part of the

  16. Vortex rings and jets recent developments in near-field dynamics

    CERN Document Server

    Yu, Simon

    2015-01-01

    In this book, recent developments in our understanding of fundamental vortex ring and jet dynamics will be discussed, with a view to shed light upon their near-field behaviour which underpins much of their far-field characteristics. The chapters provide up-to-date research findings by their respective experts and seek to link near-field flow physics of vortex ring and jet flows with end-applications in mind. Over the past decade, our knowledge on vortex ring and jet flows has grown by leaps and bounds, thanks to increasing use of high-fidelity, high-accuracy experimental techniques and numerical simulations. As such, we now have a much better appreciation and understanding on the initiation and near-field developments of vortex ring and jet flows under many varied initial and boundary conditions. Chapter 1 outlines the vortex ring pinch-off phenomenon and how it relates to the initial stages of jet formations and subsequent jet behaviour, while Chapter 2 takes a closer look at the behaviour resulting from vor...

  17. Graphene-on-Silicon Near-Field Thermophotovoltaic Cell

    NARCIS (Netherlands)

    Svetovoy, V. B.; Palasantzas, G.

    2014-01-01

    A graphene layer on top of a dielectric can dramatically influence the ability of the material for radiative heat transfer. This property of graphene is used to improve the performance and reduce costs of near-field thermophotovoltaic cells. Instead of low-band-gap semiconductors it is proposed to

  18. Near-field radiative heat transfer in mesoporous alumina

    International Nuclear Information System (INIS)

    Li Jing; Feng Yan-Hui; Zhang Xin-Xin; Huang Cong-Liang; Wang Ge

    2015-01-01

    The thermal conductivity of mesoporous material has aroused the great interest of scholars due to its wide applications such as insulation, catalyst, etc. Mesoporous alumina substrate consists of uniformly distributed, unconnected cylindrical pores. Near-field radiative heat transfer cannot be ignored, when the diameters of the pores are less than the characteristic wavelength of thermal radiation. In this paper, near-field radiation across a cylindrical pore is simulated by employing the fluctuation dissipation theorem and Green function. Such factors as the diameter of the pore, and the temperature of the material are further analyzed. The research results show that the radiative heat transfer on a mesoscale is 2∼4 orders higher than on a macroscale. The heat flux and equivalent thermal conductivity of radiation across a cylindrical pore decrease exponentially with pore diameter increasing, while increase with temperature increasing. The calculated equivalent thermal conductivity of radiation is further developed to modify the thermal conductivity of the mesoporous alumina. The combined thermal conductivity of the mesoporous alumina is obtained by using porosity weighted dilute medium and compared with the measurement. The combined thermal conductivity of mesoporous silica decreases gradually with pore diameter increasing, while increases smoothly with temperature increasing, which is in good agreement with the experimental data. The larger the porosity, the more significant the near-field effect is, which cannot be ignored. (paper)

  19. The status of near-field modelling

    International Nuclear Information System (INIS)

    Apted, M.J.

    1993-01-01

    The near-field of a high-level nuclear waste repository consists of the waste itself and of the man-made barriers engineered around it (Engineered Barrier System, EBS). The conceptual and mathematical models of repositories and EBS, and the state of the air of performance assessment of waste repositories with EBS are discussed at the meeting. 18 individual items have been indexed and abstracted for the INIS database. (R.P.)

  20. A model for electron currents near a field null

    International Nuclear Information System (INIS)

    Stark, R.A.; Miley, G.H.

    1987-01-01

    The fluid approximation is invalid near a field null, since the local electron orbit size and the magnetic scale length are comparable. To model the electron currents in this region we propose a single equation of motion describing the bulk electron dynamics. The equation applies to the plasma within one thermal orbit size of the null. The region is treated as unmagnetized; electrons are accelerated by the inductive electric field and drag on ions; damping is provided by viscosity due to electrons and collisions with ions. Through variational calculations and a particle tracking code for electrons, the size of the terms in the equation of motion have been estimated. The resulting equation of motion combines with Faraday's Law to produce a governing equation which implicitly contains the self inductive field of the electrons. This governing equation predicts that viscosity prevents complete cancellation of the ion current density by the electrons in the null region. Thus electron dynamics near the field null should not prevent the formation and deepening of field reversal using neutral-beam injection

  1. Near-field characterization of low-loss photonic crystal waveguides

    DEFF Research Database (Denmark)

    Volkov, V. S.; Bozhevolnyi, S. I.; Borel, Peter Ingo

    2005-01-01

    -nm-period lattices with different filling factors (0.76 and 0.82) and connected to access ridge waveguides. Using the near-field optical images we investigate the light propagation along PCWs for TM and TE polarization (the electric field is perpendicular/parallel to the sample surface). Efficient...

  2. Review of near-field optics and superlenses for sub-diffraction-limited nano-imaging

    Directory of Open Access Journals (Sweden)

    Wyatt Adams

    2016-10-01

    Full Text Available Near-field optics and superlenses for imaging beyond Abbe’s diffraction limit are reviewed. A comprehensive and contemporary background is given on scanning near-field microscopy and superlensing. Attention is brought to recent research leveraging scanning near-field optical microscopy with superlenses for new nano-imaging capabilities. Future research directions are explored for realizing the goal of low-cost and high-performance sub-diffraction-limited imaging systems.

  3. Radioactive waste isolation in salt: geochemistry of brine in rock salt in temperature gradients and gamma-radiation fields - a selective annotated bibliography

    International Nuclear Information System (INIS)

    Hull, A.B.; Williams, L.B.

    1985-07-01

    Evaluation of the extensive research concerning brine geochemistry and transport is critically important to successful exploitation of a salt formation for isolating high-level radioactive waste. This annotated bibliography has been compiled from documents considered to provide classic background material on the interactions between brine and rock salt, as well as the most important results from more recent research. Each summary elucidates the information or data most pertinent to situations encountered in siting, constructing, and operating a mined repository in salt for high-level radioactive waste. The research topics covered include the basic geology, depositional environment, mineralogy, and structure of evaporite and domal salts, as well as fluid inclusions, brine chemistry, thermal and gamma-radiation effects, radionuclide migration, and thermodynamic properties of salts and brines. 4 figs., 6 tabs

  4. Radioactive waste isolation in salt: geochemistry of brine in rock salt in temperature gradients and gamma-radiation fields - a selective annotated bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Hull, A.B.; Williams, L.B.

    1985-07-01

    Evaluation of the extensive research concerning brine geochemistry and transport is critically important to successful exploitation of a salt formation for isolating high-level radioactive waste. This annotated bibliography has been compiled from documents considered to provide classic background material on the interactions between brine and rock salt, as well as the most important results from more recent research. Each summary elucidates the information or data most pertinent to situations encountered in siting, constructing, and operating a mined repository in salt for high-level radioactive waste. The research topics covered include the basic geology, depositional environment, mineralogy, and structure of evaporite and domal salts, as well as fluid inclusions, brine chemistry, thermal and gamma-radiation effects, radionuclide migration, and thermodynamic properties of salts and brines. 4 figs., 6 tabs.

  5. Near-field strong coupling of single quantum dots.

    Science.gov (United States)

    Groß, Heiko; Hamm, Joachim M; Tufarelli, Tommaso; Hess, Ortwin; Hecht, Bert

    2018-03-01

    Strong coupling and the resultant mixing of light and matter states is an important asset for future quantum technologies. We demonstrate deterministic room temperature strong coupling of a mesoscopic colloidal quantum dot to a plasmonic nanoresonator at the apex of a scanning probe. Enormous Rabi splittings of up to 110 meV are accomplished by nanometer-precise positioning of the quantum dot with respect to the nanoresonator probe. We find that, in addition to a small mode volume of the nanoresonator, collective coherent coupling of quantum dot band-edge states and near-field proximity interaction are vital ingredients for the realization of near-field strong coupling of mesoscopic quantum dots. The broadband nature of the interaction paves the road toward ultrafast coherent manipulation of the coupled quantum dot-plasmon system under ambient conditions.

  6. Near-field characteristics of highly non-paraxial subwavelength optical fields with hybrid states of polarization

    International Nuclear Information System (INIS)

    Chen Rui-Pin; Gao Teng-Yue; Chew Khian-Hooi; Dai Chao-Qing; Zhou Guo-Quan; He Sai-Ling

    2017-01-01

    The vectorial structure of an optical field with hybrid states of polarization (SoP) in the near-field is studied by using the angular spectrum method of an electromagnetic beam. Physical images of the longitudinal components of evanescent waves are illustrated and compared with those of the transverse components from the vectorial structure. Our results indicate that the relative weight integrated over the transverse plane of the evanescent wave depends strongly on the number of the polarization topological charges. The shapes of the intensity profiles of the longitudinal components are different from those of the transverse components, and it can be manipulated by changing the initial SoP of the field cross-section. The longitudinal component of evanescent wave dominates the near-field region. In addition, it also leads to three-dimensional shape variations of the optical field and the optical spin angular momentum flux density distributions. (paper)

  7. Near-field interaction of colloid near wavy walls

    Science.gov (United States)

    Luo, Yimin; Serra, Francesca; Wong, Denise; Steager, Edward; Stebe, Kathleen

    Anisotropic media can be used to manipulate colloids, in tandem with carefully designed boundary conditions. For example, in bulk nematic liquid crystal, a wall with homeotropic anchoring repels a colloid with the same anchoring; yet by changing the surface topography from planar to concave, one can turn repulsion into attraction. We explore the behaviors of micro-particles with associated topological defects (hedgehogs or Saturn rings) near wavy walls. The walls locally excite disturbance, which decays into bulk. The range of influence is related to the curvature. The distortion can be used to position particles, either directly on the structure or at a distance away, based on the ``splay-matching'' rules. When distortion becomes stronger through the deepening of the well, the splay field created by the wall can prompt transformation from a Saturn ring to a hedgehog. We combine wells of different wavelength and depth to direct colloid movement. We apply a magnetic field to reset the initial position of ferromagnetic colloids and subsequently release them to probe the elastic energy landscape. Our platform enables manipulation, particle selection, and a detailed study of defect structure under the influence of curvature. Army Research Office.

  8. Photodetachment of negative ion in a gradient electric field near a metal surface

    International Nuclear Information System (INIS)

    Liu Tian-Qi; Wang De-Hua; Han Cai; Liu Jiang; Liang Dong-Qi; Xie Si-Cheng

    2012-01-01

    Based on closed-orbit theory, the photodetachment of H − in a gradient electric field near a metal surface is studied. It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface. With the increase of the gradient of the electric field, the oscillation in the photodetachment cross section becomes strengthened. Besides, in contrast to the photodetachment of H − near a metal surface in a uniform electric field, the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged. Therefore, we can use the gradient electric field to control the photodetachment of negative ions near a metal surface. We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces, cavities, and ion traps. (atomic and molecular physics)

  9. On the Seismic Response of Protected and Unprotected Middle-Rise Steel Frames in Far-Field and Near-Field Areas

    Directory of Open Access Journals (Sweden)

    Dora Foti

    2014-01-01

    Full Text Available Several steel moment-resisting framed buildings were seriously damaged during Northridge (1994; Kobe (1995; Kocaeli, Turkey (1999, earthquakes. Indeed, for all these cases, the earthquake source was located under the urban area and most victims were in near-field areas. In fact near-field ground motions show velocity and displacement peaks higher than far-field ones. Therefore, the importance of considering near-field ground motion effects in the seismic design of structures is clear. This study analyzes the seismic response of five-story steel moment-resisting frames subjected to Loma Prieta (1989 earthquake—Gilroy (far-field register and Santa Cruz (near-field register. The design of the frames verifies all the resistance and stability Eurocodes’ requirements and the first mode has been determined from previous shaking-table tests. In the frames two diagonal braces are installed in different positions. Therefore, ten cases with different periods are considered. Also, friction dampers are installed in substitution of the braces. The behaviour of the braced models under the far-field and the near-field records is analysed. The responses of the aforementioned frames equipped with friction dampers and subjected to the same ground motions are discussed. The maximum response of the examined model structures with and without passive dampers is analysed in terms of damage indices, acceleration amplification, base shear, and interstory drifts.

  10. Near-field radiation between graphene-covered carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Richard Z.; Liu, Xianglei; Zhang, Zhuomin M., E-mail: zhuomin.zhang@me.gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2015-05-15

    It has been shown that at small separation distances, thermal radiation between hyperbolic metamaterials is enhanced over blackbodies. This theoretical study considers near-field radiation when graphene is covered on the surfaces of two semi-infinite vertically aligned carbon nanotube (VACNT) arrays separated by a sub-micron vacuum gap. Doped graphene is found to improve photon tunneling in a broad hyperbolic frequency range, due to the interaction with graphene-graphene surface plasmon polaritons (SPP). In order to elucidate the SPP resonance between graphene on hyperbolic substrates, vacuum-suspended graphene sheets separated by similar gap distances are compared. Increasing the Fermi energy through doping shifts the spectral heat flux peak toward higher frequencies. Although the presence of graphene on VACNT does not offer huge near-field heat flux enhancement over uncovered VACNT, this study identifies conditions (i.e., gap distance and doping level) that best utilize graphene to augment near-field radiation. Through the investigation of spatial Poynting vectors, heavily doped graphene is found to increase penetration depths in hyperbolic modes and the result is sensitive to the frequency regime. This study may have an impact on designing carbon-based vacuum thermophotovoltaics and thermal switches.

  11. Maximal near-field radiative heat transfer between two plates

    Science.gov (United States)

    Nefzaoui, Elyes; Ezzahri, Younès; Drévillon, Jérémie; Joulain, Karl

    2013-09-01

    Near-field radiative transfer is a promising way to significantly and simultaneously enhance both thermo-photovoltaic (TPV) devices power densities and efficiencies. A parametric study of Drude and Lorentz models performances in maximizing near-field radiative heat transfer between two semi-infinite planes separated by nanometric distances at room temperature is presented in this paper. Optimal parameters of these models that provide optical properties maximizing the radiative heat flux are reported and compared to real materials usually considered in similar studies, silicon carbide and heavily doped silicon in this case. Results are obtained by exact and approximate (in the extreme near-field regime and the electrostatic limit hypothesis) calculations. The two methods are compared in terms of accuracy and CPU resources consumption. Their differences are explained according to a mesoscopic description of nearfield radiative heat transfer. Finally, the frequently assumed hypothesis which states a maximal radiative heat transfer when the two semi-infinite planes are of identical materials is numerically confirmed. Its subsequent practical constraints are then discussed. Presented results enlighten relevant paths to follow in order to choose or design materials maximizing nano-TPV devices performances.

  12. Analytic Optimization of Near-Field Optical Chirality Enhancement

    Science.gov (United States)

    2017-01-01

    We present an analytic derivation for the enhancement of local optical chirality in the near field of plasmonic nanostructures by tuning the far-field polarization of external light. We illustrate the results by means of simulations with an achiral and a chiral nanostructure assembly and demonstrate that local optical chirality is significantly enhanced with respect to circular polarization in free space. The optimal external far-field polarizations are different from both circular and linear. Symmetry properties of the nanostructure can be exploited to determine whether the optimal far-field polarization is circular. Furthermore, the optimal far-field polarization depends on the frequency, which results in complex-shaped laser pulses for broadband optimization. PMID:28239617

  13. NRC nuclear waste geochemistry 1983

    International Nuclear Information System (INIS)

    Alexander, D.H.; Birchard, G.F.

    1984-05-01

    The purpose of the meeting was to present results from NRC-sponsored research and to identify regulatory research issues which need to be addressed prior to licensing a high-level waste repository. Important summaries of technical issues and recommendations are included with each paper. The issue reflect areas of technical uncertainty addressed by the NRC Research program in geochemistry. The objectives of the NRC Research Program in geochemistry are to provide a technical basis for waste management rulemaking, to provide the NRC Waste Management Licensing Office with information that can be used to support sound licensing decisions, and to identify investigations that need to be conducted by DOE to support a license application. Individual papers were processed for inclusion in the Energy Data Base

  14. Topological study of magnetic field near a neutral point

    International Nuclear Information System (INIS)

    Fukao, Shoichiro; Ugai, Masayuki; Tsuda, Takao.

    1975-01-01

    Configuration of magnetic fields near a neutral point is re-examined by a topological analysis. The so-called X-and 0-type magnetic fields respectively occupy their own seat in our classified table. Then the existence of the spiral and node types of configuration will be shown by the analysis. (auth.)

  15. Quantum vacuum energy near a black hole: the Maxwell field

    International Nuclear Information System (INIS)

    Elster, T.

    1984-01-01

    A quantised Maxwell field is considered propagating in the gravitational field of a Schwarzschild black hole. The vector Hartle-Hawking propagator is defined on the Riemannian section of the analytically continued space-time and expanded in terms of four-dimensional vector spherical harmonics. The equations for the radial functions appearing in the expansion are derived for both odd and even parity. Using the expansion of the vector Hartle-Hawking propagator, the point-separated expectation value of the Maxwellian energy-momentum tensor in the Hartle-Hawking vacuum is derived. The renormalised values of radial pressure, tangential pressure and energy density are obtained near the horizon of the black hole. In contrast to the scalar field, the Maxwell field exhibits a positive energy density near the horizon in the Hartle-Hawking vacuum state. (author)

  16. Research on evaluation of coupled thermo-hydro-mechanical phenomena in the near-field

    International Nuclear Information System (INIS)

    Chijimatsu, Masakazu; Imai, Hisashi; Fukutome, Kazuhito; Kayukawa, Koji; Sasaki, Hajime; Moro, Yoshiji

    2004-02-01

    After emplacement of the engineered barrier system (EBS), it is expected that the near-field environment will be impacted by phenomena such as heat dissipation by conduction and other heat transfer mechanisms, infiltration of groundwater from the surrounding rock in the engineered barrier system, stress imposed by the overburden pressure and generation of swelling pressure in the buffer due to water infiltration. In order to recognize and evaluate these coupled thermo-hydro-mechanical (THM) phenomena, it is necessary to make a confidence of the mathematical models and computer codes. Evaluating these coupled THM phenomena is important in order to clarify the initial transient behavior of the EBS within the near field. DECOVALEX project is an international co-operative project for the DEvelopment of COupled models and their VALidation against EXperiments in nuclear waste isolation and it is significance to participate this project and to apply the code for the validation. Therefore, we tried to apply the developed numerical code against the subjects of DECOVALEX. We carried out the simulation against the Task 1 (simulation of FEBEX in-situ full-scale experiment), Task 3 BMT1 (Bench Mark Test against the near field coupling phenomena) and Task 3 BMT2 (Bench Mark Test against the up-scaling of fractured rock mass). This report shows the simulation results against these tasks. Furthermore, technical investigations about the in-situ full-scale experiment (called Prototype Repository Project) in Aespoe HRL facility by SKB of Sweden were performed. In order to evaluate the coupled phenomena in the engineered barrier, we use the new swelling model based on the theoretical approach. In this paper, we introduce the modeling approach and applicability about the new model. (author)

  17. Quantum field theory near surfaces of discontinuity

    International Nuclear Information System (INIS)

    Onishi, H.T.

    1981-01-01

    This work deals with the problem of a quantized scalar field propagating near a surface of discontinuity. The proper time formalism is employed to express the Green's function and stress tensor as proper time integrals of a transformation function. The transformation function is calculated by a WKB approximation which exhibits the essential singularities generated by the high frequency behavior of waves propagating near the surface. Two singularities are present, the usual direct singularity and an additional reflected singularity generated by the high frequency behavior of waves reflected by the discontinuity. The stress tensor is calculated by dimensional continuation. The results are employed to analyze energy generated by the surface

  18. Biological applications of near-field scanning optical microscopy

    NARCIS (Netherlands)

    Moers, M.H.P.; Moers, Marco H.P.; Ruiter, A.G.T.; Jalocha, A.; Jalocha, Alain; van Hulst, N.F.

    1995-01-01

    Near-field Scanning Optical Microscopy (NSOM) is a true optical microscopic technique allowing fluorescence, absorption, reflection and polarization contrast with the additional advantage of nanometer lateral resolution, unlimited by diffraction and operation at ambient conditions. NSOM based on

  19. Organic geochemistry of fossil resins from the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Havelcová, Martina; Sýkorová, Ivana; Mach, K.; Dvořák, Z.

    2014-01-01

    Roč. 10, August (2014), s. 303-312 ISSN 1878-5220. [Geochemistry of the Earth's Surface (GES) Meeting /10./. Paris, 18.08.2014-23.08.2014] R&D Projects: GA ČR(CZ) GA13-18482S Institutional support: RVO:67985891 Keywords : fossil resin * amber * resinite * TMAH-Py-GC/MS Subject RIV: DD - Geochemistry

  20. Near field studies within the SKB 91 Project

    International Nuclear Information System (INIS)

    Widen, H.; Bengtsson, A.; Grundfelt, B.

    1991-06-01

    A number of near field studies was preformed during the early part of the SKB91 project. This report summaries this work and includes: - Simulation of the steady release from the near field with different time for canister penetration. - Simulation of the release from a repository with 5300 canisters with different penetration times for different parts of the canisters due to manufacturing error, glaciations, inner over pressure and corrosion. - Calculation with a numerical model of the transient release of the instantaneously dissolvable species and the effect of different boundary conditions both at the canister/bentonite and the bentonite/rock interface. - Description of the implementation of a resistance network model for the calculation of the steady state transport resistances in the different pathways from the canisters. - Comparison of two analytical models for the calculation of the release of the instantaneously dissolvable species. (au)

  1. Manipulation of local optical properties and structures in molybdenum-disulfide monolayers using electric field-assisted near-field techniques.

    Science.gov (United States)

    Nozaki, Junji; Fukumura, Musashi; Aoki, Takaaki; Maniwa, Yutaka; Yomogida, Yohei; Yanagi, Kazuhiro

    2017-04-05

    Remarkable optical properties, such as quantum light emission and large optical nonlinearity, have been observed in peculiar local sites of transition metal dichalcogenide monolayers, and the ability to tune such properties is of great importance for their optoelectronic applications. For that purpose, it is crucial to elucidate and tune their local optical properties simultaneously. Here, we develop an electric field-assisted near-field technique. Using this technique we can clarify and tune the local optical properties simultaneously with a spatial resolution of approximately 100 nm due to the electric field from the cantilever. The photoluminescence at local sites in molybdenum-disulfide (MoS 2 ) monolayers is reversibly modulated, and the inhomogeneity of the charge neutral points and quantum yields is suggested. We successfully etch MoS 2 crystals and fabricate nanoribbons using near-field techniques in combination with an electric field. This study creates a way to tune the local optical properties and to freely design the structural shapes of atomic monolayers using near-field optics.

  2. Geochemistry of sediments of the eastern continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Mascarenhas, A.; Paropkari, A.L.; Murty, P.S.N.

    The bulk and partition geochemistry of Al, Fe, Ti, Mn, Zn, and Cu have been investigated in sediments of the eastern continental shelf of India. The results show that (1) the bulk geochemistry varies from one shelf unit to the other, (2) all...

  3. Fast Near-Field Calculation for Volume Integral Equations for Layered Media

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Meincke, Peter; Breinbjerg, Olav

    2005-01-01

    . Afterwards, the scattered electric field can be easily computed at a regular rectangular grid on any horizontal plane us-ing a 2-dimensional FFT. This approach provides significant speedup in the near-field calculation in comparison to a straightforward numerical evaluation of the ra-diation integral since......An efficient technique based on the Fast Fourier Transform (FFT) for calculating near-field scattering by dielectric objects in layered media is presented. A higher or-der method of moments technique is employed to solve the volume integral equation for the unknown induced volume current density...

  4. Geochemistry of radioactive waste disposal

    International Nuclear Information System (INIS)

    Bird, G.W.

    1979-01-01

    Safe, permanent disposal of radioactive wastes requires isolation of a number of elements including Se, Tc, I, Sr, Cs, Pd, u, Np, Pu and Cm from the environment for a long period of time. The aquatic chemistry of these elements ranges from simple anionic (I - ,IO 3 - ) and cationic (Cs + ,Sr ++ ) forms to multivalent hydrolyzed complexes which can be anionic or cationic (Pu(OH) 2 + ,Pu(OH) 3 + , PuO 2 (CO 3 )(OH) - ,PuO 2 Cl - ,etc.) depending on the chemical environment. The parameters which can affect repository safety are rate of access and composition of grounwater, stability of the waste container, stability of the waste form, rock-water-waste interactons, and dilution and dispersion as the waste moves away from the repository site. Our overall research program on radioactive waste disposal includes corrosion studies of containment systems hydrothermal stability of various waste forms, and geochemical behaviour of various nuclides including solubilities, redox equilibria, hydrolysis, colloid fomation and transport ion exchange equilibria and adsorption on mineral surfaces and irreversible precipitation reactions. This paper discusses the geochemistry of I, Se, Tc, Cs, Sr and the actinide elements and potential mechanisms by which the mobility could be retarded if necessary

  5. Near-Field Enhanced Photochemistry of Single Molecules in a Scanning Tunneling Microscope Junction.

    Science.gov (United States)

    Böckmann, Hannes; Gawinkowski, Sylwester; Waluk, Jacek; Raschke, Markus B; Wolf, Martin; Kumagai, Takashi

    2018-01-10

    Optical near-field excitation of metallic nanostructures can be used to enhance photochemical reactions. The enhancement under visible light illumination is of particular interest because it can facilitate the use of sunlight to promote photocatalytic chemical and energy conversion. However, few studies have yet addressed optical near-field induced chemistry, in particular at the single-molecule level. In this Letter, we report the near-field enhanced tautomerization of porphycene on a Cu(111) surface in a scanning tunneling microscope (STM) junction. The light-induced tautomerization is mediated by photogenerated carriers in the Cu substrate. It is revealed that the reaction cross section is significantly enhanced in the presence of a Au tip compared to the far-field induced process. The strong enhancement occurs in the red and near-infrared spectral range for Au tips, whereas a W tip shows a much weaker enhancement, suggesting that excitation of the localized plasmon resonance contributes to the process. Additionally, using the precise tip-surface distance control of the STM, the near-field enhanced tautomerization is examined in and out of the tunneling regime. Our results suggest that the enhancement is attributed to the increased carrier generation rate via decay of the excited near-field in the STM junction. Additionally, optically excited tunneling electrons also contribute to the process in the tunneling regime.

  6. Piezoresistor-equipped fluorescence-based cantilever probe for near-field scanning.

    Science.gov (United States)

    Kan, Tetsuo; Matsumoto, Kiyoshi; Shimoyama, Isao

    2007-08-01

    Scanning near-field optical microscopes (SNOMs) with fluorescence-based probes are promising tools for evaluating the optical characteristics of nanoaperture devices used for biological investigations, and this article reports on the development of a microfabricated fluorescence-based SNOM probe with a piezoresistor. The piezoresistor was built into a two-legged root of a 160-microm-long cantilever. To improve the displacement sensitivity of the cantilever, the piezoresistor's doped area was shallowly formed on the cantilever surface. A fluorescent bead, 500 nm in diameter, was attached to the bottom of the cantilever end as a light-intensity-sensitive material in the visible-light range. The surface of the scanned sample was simply detected by the probe's end being displaced by contact with the sample. Measuring displacements piezoresistively is advantageous because it eliminates the noise arising from the use of the optical-lever method and is free of any disturbance in the absorption or the emission spectrum of the fluorescent material at the probe tip. The displacement sensitivity was estimated to be 6.1 x 10(-6) nm(-1), and the minimum measurable displacement was small enough for near-field measurement. This probe enabled clear scanning images of the light field near a 300 x 300 nm(2) aperture to be obtained in the near-field region where the tip-sample distance is much shorter than the light wavelength. This scanning result indicates that the piezoresistive way of tip-sample distance regulation is effective for characterizing nanoaperture optical devices.

  7. Magnetic field considerations in fusion power plant environs

    International Nuclear Information System (INIS)

    Liemohn, H.B.; Lessor, D.L.; Duane, B.H.

    1976-09-01

    A summary of magnetic field production mechanisms and effects is given. Discussions are included on the following areas: (1) stray magnetic and electric fields from tokamaks, (2) methods for reducing magnetic fields, (3) economics of magnetic field reductions, (4) forces on magnetizable objects near magnetic confinement fusion reactors, (5) electric field transients in tokamaks, (6) attenuation and decay of electromagnetic fields, and (7) magnetic field transients from tokamak malfunctions

  8. Direct subwavelength imaging and control of near-field localization in individual silver nanocubes

    Energy Technology Data Exchange (ETDEWEB)

    Mårsell, Erik; Svärd, Robin; Miranda, Miguel; Guo, Chen; Harth, Anne; Lorek, Eleonora; Mauritsson, Johan; Arnold, Cord L.; L' Huillier, Anne; Mikkelsen, Anders; Losquin, Arthur, E-mail: arthur.losquin@fysik.lth.se [Department of Physics, Lund University, PO Box 118, 221 00 Lund (Sweden); Xu, Hongxing [Department of Physics, Lund University, PO Box 118, 221 00 Lund (Sweden); School of Physics and Technology and Institute for Advanced Studies, Wuhan University, Wuhan 430072 (China)

    2015-11-16

    We demonstrate the control of near-field localization within individual silver nanocubes through photoemission electron microscopy combined with broadband, few-cycle laser pulses. We find that the near-field is concentrated at the corners of the cubes, and that it can be efficiently localized to different individual corners depending on the polarization of the incoming light. The experimental results are confirmed by finite-difference time-domain simulations, which also provide an intuitive picture of polarization dependent near-field localization in nanocubes.

  9. Integration of inorganic and isotopic geochemistry with endocrine disruption activity assays to assess risks to water resources near unconventional oil and gas development in Garfield County, CO.

    Science.gov (United States)

    Harkness, J.; Kassotis, C.; Cornelius, J.; Nagel, S.; Vengosh, A.

    2016-12-01

    The rise of hydraulic fracturing in the United States has sparked a debate about the impact of oil and gas development on the quality of water resources. Wastewater associated with hydraulic fracturing includes injection fluid that is a mixture of sand, freshwater and synthetic organic chemicals, flowback water that is a mixture of injection fluid and formation brine, and produced water that is primarily brine. The fluids range in salinity and chemical composition that can have different environmental impacts. We analyzed the inorganic and isotope geochemistry of 58 surface and groundwater samples near and away from unconventional oil and gas operations (UOG), along with hormonal profiles via bioassays. Cl (0.12 to 198 mg/L), Na (1.2 to 518 mg/L) and Sr (1.4 to 2410 ug/L) were higher in both groundwater and surface water near UOG wells. Four surface waters and one groundwater had Br/Cl indicative of brine contamination (>1.5x10-3). Three of the SW samples also had 87Sr/86Sr ratios similar to values found in produced or flowback water (0.7118 and 0.7158, respectively) from the Williams-Fork formation and elevated compared to background ratios (0.71062 to 0.7115). Increased progestogenic activity was observed in groundwater near UOG operations and inncreased estrogenic, androgenic, progestogenic, anti-androgenic, anti-progestogenic, and anti-glucocorticoid activities in surface water near UOG operations. The association of increased EDCs with inorganic and isotopic indicators of UOG wastewater provides evidence for possible environmental and health impacts from drilling activity.

  10. Near-Field Source Localization Using a Special Cumulant Matrix

    Science.gov (United States)

    Cui, Han; Wei, Gang

    A new near-field source localization algorithm based on a uniform linear array was proposed. The proposed algorithm estimates each parameter separately but does not need pairing parameters. It can be divided into two important steps. The first step is bearing-related electric angle estimation based on the ESPRIT algorithm by constructing a special cumulant matrix. The second step is the other electric angle estimation based on the 1-D MUSIC spectrum. It offers much lower computational complexity than the traditional near-field 2-D MUSIC algorithm and has better performance than the high-order ESPRIT algorithm. Simulation results demonstrate that the performance of the proposed algorithm is close to the Cramer-Rao Bound (CRB).

  11. Plasmonic superfocusing on metallic tips for near-field optical imaging and spectroscopy

    Science.gov (United States)

    Neacsu, Catalin C.; Olmon, Rob; Berweger, Samuel; Kappus, Alexandria; Kirchner, Friedrich; Ropers, Claus; Saraf, Lax; Raschke, Markus B.

    2008-03-01

    Realization of localized light sources through nonlocal excitation is important in the context of plasmon photonics, molecular sensing, and in particular near-field optical techniques. Here, the efficient conversion of propagating surface plasmons, launched on the shaft of a scanning probe tip, into localized plasmon at the apex provides a true nanoconfined light source. Focused ion beam milling is used to generate periodic surface nanostructures on the tip shaft that allow for tailoring the plasmon excitation. Using ultrashort visible and mid-IR transients the dynamics of the propagation and subsequent scattered emission is characterized. The strong field enhancement and spatial field confinement at the apex is demonstrated studying the coupling of the tip in near-field interaction with a flat sample surface. It is used in scattering near-field spectroscopic imaging (s-SNOM) to probe surface nanostructures with spatial resolution down to 10 nm.

  12. Static field influences on transcranial magnetic stimulation: considerations for TMS in the scanner environment.

    Science.gov (United States)

    Yau, Jeffrey M; Jalinous, Reza; Cantarero, Gabriela L; Desmond, John E

    2014-01-01

    Transcranial magnetic stimulation (TMS) can be combined with functional magnetic resonance imaging (fMRI) to simultaneously manipulate and monitor human cortical responses. Although tremendous efforts have been directed at characterizing the impact of TMS on image acquisition, the influence of the scanner's static field on the TMS coil has received limited attention. The aim of this study was to characterize the influence of the scanner's static field on TMS. We hypothesized that spatial variations in the static field could account for TMS field variations in the scanner environment. Using an MRI-compatible TMS coil, we estimated TMS field strengths based on TMS-induced voltage changes measured in a search coil. We compared peak field strengths obtained with the TMS coil positioned at different locations (B0 field vs fringe field) and orientations in the static field. We also measured the scanner's static field to derive a field map to account for TMS field variations. TMS field strength scaled depending on coil location and orientation with respect to the static field. Larger TMS field variations were observed in fringe field regions near the gantry as compared to regions inside the bore or further removed from the bore. The scanner's static field also exhibited the greatest spatial variations in fringe field regions near the gantry. The scanner's static field influences TMS fields and spatial variations in the static field correlate with TMS field variations. Coil orientation changes in the B0 field did not result in substantial TMS field variations. TMS field variations can be minimized by delivering TMS in the bore or outside of the 0-70 cm region from the bore entrance. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Near field plasmonic gradient effects on high vacuum tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Fang, Yurui; Zhang, Zhenglong; Chen, Li; Sun, Mengtao

    2015-01-14

    Near field gradient effects in high vacuum tip-enhanced Raman spectroscopy (HV-TERS) are a recent developing ultra-sensitive optical and spectral analysis technology on the nanoscale, based on the plasmons and plasmonic gradient enhancement in the near field and under high vacuum. HV-TERS can not only be used to detect ultra-sensitive Raman spectra enhanced by surface plasmon, but also to detect clear molecular IR-active modes enhanced by strongly plasmonic gradient. Furthermore, the molecular overtone modes and combinational modes can also be experimentally measured, where the Fermi resonance and Darling-Dennison resonance were successfully observed in HV-TERS. Theoretical calculations using electromagnetic field theory firmly supported experimental observation. The intensity ratio of the plasmon gradient term over the linear plasmon term can reach values greater than 1. Theoretical calculations also revealed that with the increase in gap distance between tip and substrate, the decrease in the plasmon gradient was more significant than the decrease in plasmon intensity, which is the reason that the gradient Raman can be only observed in the near field. Recent experimental results of near field gradient effects on HV-TERS were summarized, following the section of the theoretical analysis.

  14. Sensitivities of Near-field Tsunami Forecasts to Megathrust Deformation Predictions

    Science.gov (United States)

    Tung, S.; Masterlark, T.

    2018-02-01

    This study reveals how modeling configurations of forward and inverse analyses of coseismic deformation data influence the estimations of seismic and tsunami sources. We illuminate how the predictions of near-field tsunami change when (1) a heterogeneous (HET) distribution of crustal material is introduced to the elastic dislocation model, and (2) the near-trench rupture is either encouraged or suppressed to invert spontaneous coseismic displacements. Hypothetical scenarios of megathrust earthquakes are studied with synthetic Global Positioning System displacements in Cascadia. Finite-element models are designed to mimic the subsurface heterogeneity across the curved subduction margin. The HET lithospheric domain modifies the seafloor displacement field and alters tsunami predictions from those of a homogeneous (HOM) crust. Uncertainties persist as the inverse analyses of geodetic data produce nonrealistic slip artifacts over the HOM domain, which propagates into the prediction errors of subsequent tsunami arrival and amplitudes. A stochastic analysis further shows that the uncertainties of seismic tomography models do not degrade the solution accuracy of HET over HOM. Whether the source ruptures near the trench also controls the details of the seafloor disturbance. Deeper subsurface slips induce more seafloor uplift near the coast and cause an earlier arrival of tsunami waves than surface-slipping events. We suggest using the solutions of zero-updip-slip and zero-updip-slip-gradient rupture boundary conditions as end-members to constrain the tsunami behavior for forecasting purposes. The findings are important for the near-field tsunami warning that primarily relies on the near-real-time geodetic or seismic data for source calibration before megawaves hit the nearest shore upon tsunamigenic events.

  15. Rigorous numerical modeling of scattering-type scanning near-field optical microscopy and spectroscopy

    Science.gov (United States)

    Chen, Xinzhong; Lo, Chiu Fan Bowen; Zheng, William; Hu, Hai; Dai, Qing; Liu, Mengkun

    2017-11-01

    Over the last decade, scattering-type scanning near-field optical microscopy and spectroscopy have been widely used in nano-photonics and material research due to their fine spatial resolution and broad spectral range. A number of simplified analytical models have been proposed to quantitatively understand the tip-scattered near-field signal. However, a rigorous interpretation of the experimental results is still lacking at this stage. Numerical modelings, on the other hand, are mostly done by simulating the local electric field slightly above the sample surface, which only qualitatively represents the near-field signal rendered by the tip-sample interaction. In this work, we performed a more comprehensive numerical simulation which is based on realistic experimental parameters and signal extraction procedures. By directly comparing to the experiments as well as other simulation efforts, our methods offer a more accurate quantitative description of the near-field signal, paving the way for future studies of complex systems at the nanoscale.

  16. Analysis of artificial opals by scanning near field optical microscopy

    Science.gov (United States)

    Barrio, J.; Lozano, G.; Lamela, J.; Lifante, G.; Dorado, L. A.; Depine, R. A.; Jaque, F.; Míguez, H.

    2011-04-01

    Herein we present a detailed analysis of the optical response of artificial opal films realized employing a near-field scanning optical microscope in collection and transmission modes. Near-field patterns measured at the rear surface when a plane wave impinges on the front face are presented with the finding that optical intensity maps present a clear correlation with the periodic arrangement of the outer surface. Calculations based on the vector Korringa-Kohn-Rostoker method reproduce the different profiles experimentally observed as well as the response to the polarization of the incident field. These observations constitute the first experimental confirmation of the collective lattice resonances that give rise to the optical response of these three dimensional periodic structures in the high-energy range.

  17. Short presentation on some researches activities about near field earthquakes

    International Nuclear Information System (INIS)

    Donald, John

    2002-01-01

    The major hazard posed by earthquakes is often thought to be due to moderate to large magnitude events. However, there have been many cases where earthquakes of moderate and even small magnitude have caused very significant destruction when they have coincided with population centres. Even though the area of intense ground shaking caused by such events is generally small, the epicentral motions can be severe enough to cause damage even in well-engineered structures. Two issues are addressed here, the first being the identification of the minimum earthquake magnitude likely to cause damage to engineered structures and the limits of the near-field for small-to-moderate magnitude earthquakes. The second issue addressed is whether features of near-field ground motions such as directivity, which can significantly enhance the destructive potential, occur in small-to-moderate magnitude events. The accelerograms from the 1986 San Salvador (El Salvador) earthquake indicate that it may be non conservative to assume that near-field directivity effects only need to be considered for earthquakes of moment magnitude M 6.5 and greater. (author)

  18. Model development to evaluate evolution of redox conditions in the near field

    International Nuclear Information System (INIS)

    Chiba, Tamotsu; Miki, Takahito; Inagaki, Manabu; Sasamoto, Hiroshi; Yui, Mikazu

    1999-02-01

    Deep underground is thought to be a potential place for high level radioactive waste repository. It is believed that the chemical condition of deep groundwater is generally anoxic and reducing. However, during construction and operation phase of repository, oxygen will diffuse some distance into the surrounding rock mass, and diffused oxygen may remain in the surrounding rock mass even after repository closure. In such a case, the transitional redox condition around the drift is not preferable in view point of safety assessment for HLW disposal. Hence, it is very important to evaluate evolution of redox conditions in the near field. This report describes the status of model development to evaluate evolution of redox conditions in the near field. We use the commercial solver to equate the mathematical equations which mean evolution of redox condition in the near field. The target area modeled in this report are near field rock mass and engineered barrier (buffer). In case of near field rock mass, we consider the following two geological media: (1) porous media for sedimentary rock, (2) fractured media for crystalline rock. In case of the engineered barrier, we regard the buffer as porous media. We simulate the behavior of dissolved oxygen and Fe 2+ in groundwater during evolution of redox condition in the near field rock mass and the buffer. In case of the porous media, we consider diffusion of chemical species as dominant transport mechanism. On the other hand, in case of the fractured media, we consider diffusion of chemical species in rock matrix and advection of that (only dissolved oxygen considered in this model) in fracture as transport mechanism. We also use the rate law of iron oxidation reaction and dissolution of Fe-bearing minerals in this model besides. (author)

  19. Estimation of polarization distribution on gold nanorods system from hierarchical features of optical near-field

    Science.gov (United States)

    Uchiyama, Kazuharu; Nishikawa, Naoki; Nakagomi, Ryo; Kobayashi, Kiyoshi; Hori, Hirokazu

    2018-02-01

    To design optoelectronic functionalities in nanometer scale based on interactions of electronic system with optical near-fields, it is essential to evaluate the relationship between optical near-fields and their sources. Several theoretical studies have been performed, so far, to analyze such complex relationship to design the interaction fields of several specific scales. In this study, we have performed detailed and high-precision measurements of optical near-field structures woven by a large number of independent polarizations generated in the gold nanorods array under laser light irradiation at the resonant frequency. We have accumulated the multi-layered data of optical near-field imaging at different heights above the planar surface with the resolution of several nm by a STM-assisted scanning near-field optical microscope. Based on these data, we have performed an inverse calculation to estimate the position, direction, and strength of the local polarization buried under the flat surface of the sample. As a result of the inverse operation, we have confirmed that the complexities in the nanometer scale optical near-fields could be reconstructed by combinations of induced polarization in each gold nanorod. We have demonstrated the hierarchical properties of optical near-fields based on spatial frequency expansion and superposition of dipole fields to provide insightful information for applications such for secure multi-layered information storage.

  20. Terahertz Near-Field Imaging Using Enhanced Transmission through a Single Subwavelength Aperture

    Science.gov (United States)

    Ishihara, Kunihiko; Ikari, Tomofumi; Minamide, Hiroaki; Shikata, Jun-ichi; Ohashi, Keishi; Yokoyama, Hiroyuki; Ito, Hiromasa

    2005-07-01

    We demonstrate terahertz (THz) near-field imaging using resonantly enhanced transmission of THz-wave radiation (λ˜ 200 μm) through a bull’s eye structure (a single subwavelength aperture surrounded by concentric periodic grooves in a metal plate). The bull’s eye structure shows extremely large enhanced transmission, which has the advantage for a single subwavelength aperture. The spatial resolution for the bull’s eye structure (with an aperture diameter d=100 μm) is evaluated in the near-field region, and a resolution of 50 μm (corresponding to λ/4) is achieved. We obtain the THz near-field images of the subwavelength metal pattern with a spatial resolution below the diffraction limit.

  1. Macroscopic self-consistent model for external-reflection near-field microscopy

    International Nuclear Information System (INIS)

    Berntsen, S.; Bozhevolnaya, E.; Bozhevolnyi, S.

    1993-01-01

    The self-consistent macroscopic approach based on the Maxwell equations in two-dimensional geometry is developed to describe tip-surface interaction in external-reflection near-field microscopy. The problem is reduced to a single one-dimensional integral equation in terms of the Fourier components of the field at the plane of the sample surface. This equation is extended to take into account a pointlike scatterer placed on the sample surface. The power of light propagating toward the detector as the fiber mode is expressed by using the self-consistent field at the tip surface. Numerical results for trapezium-shaped tips are presented. The authors show that the sharper tip and the more confined fiber mode result in better resolution of the near-field microscope. Moreover, it is found that the tip-surface distance should not be too small so that better resolution is ensured. 14 refs., 10 figs

  2. The contribution of microbial mats to the arsenic geochemistry of an ancient gold mine

    International Nuclear Information System (INIS)

    Drewniak, Lukasz; Maryan, Natalia; Lewandowski, Wiktor; Kaczanowski, Szymon; Sklodowska, Aleksandra

    2012-01-01

    The ancient Zloty Stok (SW Poland) gold mine is such an environment, where different microbial communities, able to utilize inorganic arsenic species As(III) and As(V), are found. The purpose of the present study was to (i) estimate prokaryotic diversity in the microbial mats in bottom sediments of this gold mine, (ii) identify microorganisms that can metabolize arsenic, and (iii) estimate their potential role in the arsenic geochemistry of the mine and in the environment. The oxidation/reduction experiments showed that the microbial mat community may significantly contribute to arsenic contamination in groundwater. The presence of both arsenite oxidizing and dissimilatory arsenate reducing bacteria in the mat was confirmed by the detection of arsenite oxidase and dissimilatory arsenate reductase genes, respectively. This work also demonstrated that microorganisms utilizing other compounds that naturally co-occur with arsenic are present within the microbial mat community and may contribute to the arsenic geochemistry in the environment. - Highlights: ► The microbial mats from this ancient gold mine are highly diverse community. ► As(III) oxidizing and As(V) reducing bacteria are present in the mats. ► As redox transformations are linked to the metabolism of microbial mats bacteria. ► Microbial mats play a crucial role in the As biogeochemical cycle within the mine. - The microbial mats from this ancient gold mine can mediate oxidation/reduction reaction of arsenic and in this way may significantly contribute to arsenic contamination in groundwater.

  3. Antenna diagnostics for power flow in extreme near-field of a standard gain horn

    DEFF Research Database (Denmark)

    Popa, Paula Irina; Breinbjerg, Olav

    2016-01-01

    The plane wave spectrum of an aperture antenna can be calculated from a complex measurement of the radiated near- or far-field and it facilitates antenna diagnostics for the extreme near-field of the antenna. While antenna diagnostics often concerns the magnitude of the co-polar field, the plane...... wave spectrum actually allows for determination of both magnitude and phase of all three components of the electric as well as the magnetic field - and thus also the Poynting vector. In this work we focus on the Poynting vector and thus the power flow in the extreme near-field; as an example we employ...... that these oscillations are not merely a “Gibbs-like” phenomenon due to the availability of only the visible region of the plane wave spectrum and they are not caused by multiple reflections between the horn and the near-field probe - but resulted from the interference between the direct field and the edge...

  4. Assessment of the Bordas-Carnot Losses within the diffuser of tidal turbines using far-field and near-field CFD models.

    Science.gov (United States)

    Hajaali, Arthur

    2017-04-01

    This project has for ambition to analyse and further the general understanding on cross-flows interactions and behaviours at the mouth of a mini/small tidal hydropower plant and a river. Although, the study of these interactions could benefit and find applications in multiple hydraulic problems, this project concentrates its focus on the influence of the transposed turbulences generated by the cross-flow into the diffuser. These eddies affect the overall performance and efficiency of the bulb-turbines by minimizing the pressure recovery. In the past, these turbulences were accounted with the implementation of the Bordas-Carnot losses coefficient for the design of tidal project using bulb-turbines. The bulb turbine technology has been the interest and subject of many scientific papers but most of them concentrate and narrow their focus on the design of the rotor, blades and combiner. This project wants to focus the design of the diffuser by performing an analysis on the development of eddies and the turbulences using computational fluid dynamic (CFD) models. The Severn estuary is endowed with one of the highest tidal range around the hemisphere. The first part of the research requires to select case studies sites such as Briton-Ferry to virtually design mini-tidal plant in 0-Dimentional (D), 2D and 3D modelling to study development and behaviour of turbulences within the diffuser. The far-field model represents the marine environment prior and after the structure where bulb turbines are located. The near-field modelling has allowed researcher to study at much higher resolution and precision the design of a single turbine feeding model with predetermined and fix boundary condition. For this reason, a near-field model is required to study in depth the behaviour and evolution of the turbulence with the diffuser. One of the main challenge and advancement of this research is to find a methodology and system to link the far-field and near-field modelling to produce an

  5. A review of models for near-field exposure pathways of chemicals in consumer products

    DEFF Research Database (Denmark)

    Huang, Lei; Ernstoff, Alexi; Fantke, Peter

    2017-01-01

    able to quantify the multiple transfers of chemicals from products used near-field to humans. The present review therefore aims at an in-depth overview of modeling approaches for near-field chemical release and human exposure pathways associated with consumer products. It focuses on lower......-tier, mechanistic models suitable for life cycle assessments (LCA), chemical alternative assessment (CAA) and high-throughput screening risk assessment (HTS). Chemicals in a product enter the near-field via a defined “compartment of entry”, are transformed or transferred to adjacent compartments, and eventually end......Exposure to chemicals in consumer products has been gaining increasing attention, with multiple studies showing that near-field exposures from products is high compared to far-field exposures. Regarding the numerous chemical-product combinations, there is a need for an overarching review of models...

  6. Patch near field acoustic holography based on particle velocity measurements

    DEFF Research Database (Denmark)

    Zhang, Yong-Bin; Jacobsen, Finn; Bi, Chuan-Xing

    2009-01-01

    Patch near field acoustic holography (PNAH) based on sound pressure measurements makes it possible to reconstruct the source field near a source by measuring the sound pressure at positions on a surface. that is comparable in size to the source region of concern. Particle velocity is an alternative...... examines the use of particle velocity as the input of PNAH. Because the particle velocity decays faster toward the edges of the measurement aperture than the pressure does and because the wave number ratio that enters into the inverse propagator from pressure to velocity amplifies high spatial frequencies...

  7. Superresolution Near-field Imaging with Surface Waves

    KAUST Repository

    Fu, Lei

    2017-10-21

    We present the theory for near-field superresolution imaging with surface waves and time reverse mirrors (TRMs). Theoretical formulas and numerical results show that applying the TRM operation to surface waves in an elastic half-space can achieve superresolution imaging of subwavelength scatterers if they are located less than about 1/2 of the shear wavelength from the source line. We also show that the TRM operation for a single frequency is equivalent to natural migration, which uses the recorded data to approximate the Green’s functions for migration, and only costs O(N4) algebraic operations for poststack migration compared to O(N6) operations for natural prestack migration. Here, we assume the sources and receivers are on an N × N grid and there are N2 trial image points on the free surface. Our theoretical predictions of superresolution are validated with tests on synthetic data. The field-data tests suggest that hidden faults at the near surface can be detected with subwavelength imaging of surface waves by using the TRM operation if they are no deeper than about 1/2 the dominant shear wavelength.

  8. Probing strong-field general relativity near black holes

    CERN Multimedia

    CERN. Geneva; Alvarez-Gaumé, Luís

    2005-01-01

    Nature has sprinkled black holes of various sizes throughout the universe, from stellar mass black holes in X-ray sources to supermassive black holes of billions of solar masses in quasars. Astronomers today are probing the spacetime near black holes using X-rays, and gravitational waves will open a different view in the near future. These tools give us an unprecedented opportunity to test ultra-strong-field general relativity, including the fundamental theorem of the uniqueness of the Kerr metric and Roger Penrose's cosmic censorship conjecture. Already, fascinating studies of spectral lines are showing the extreme gravitational lensing effects near black holes and allowing crude measurements of black hole spin. When the ESA-NASA gravitational wave detector LISA begins its observations in about 10 years, it will make measurements of dynamical spacetimes near black holes with an accuracy greater even than that which theoreticians can reach with their computations today. Most importantly, when gravitational wa...

  9. THz near-field imaging of biological tissues employing synchrotron radiation (Invited Paper)

    Science.gov (United States)

    Schade, Ulrich; Holldack, Karsten; Martin, Michael C.; Fried, Daniel

    2005-04-01

    Terahertz scanning near-field infrared microscopy (SNIM) below 1 THz is demonstrated. The near-field technique benefits from the broadband and highly brilliant coherent synchrotron radiation (CSR) from an electron storage ring and from a detection method based on locking on to the intrinsic time structure of the synchrotron radiation. The scanning microscope utilizes conical waveguides as near-field probes with apertures smaller than the wavelength. Different cone approaches have been investigated to obtain maximum transmittance. Together with a Martin-Puplett spectrometer the set-up enables spectroscopic mapping of the transmittance of samples well below the diffraction limit. Spatial resolution down to about λ/40 at 2 wavenumbers (0.06 THz) is derived from the transmittance spectra of the near-field probes. The potential of the technique is exemplified by imaging biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 μm at about 12 wavenumbers (0.36 THz). The THz near-field images reveal distinct structural differences of leaves from different plants investigated. The technique presented also allows spectral imaging of bulky organic tissues. Human teeth samples of various thicknesses have been imaged between 2 and 20 wavenumbers (between 0.06 and 0.6 THz). Regions of enamel and dentin within tooth samples are spatially and spectrally resolved, and buried caries lesions are imaged through both the outer enamel and into the underlying dentin.

  10. Report of near field group

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, R.B.; Baggett, N.; Claus, J.; Fernow, R.; Stumer, I.; Figueroa, H.; Kroll, N.; Funk, W.; Lee-Whiting, G.; Pickup, M.

    1985-04-01

    Substantial progress since the Los Alamos Workshop two years ago is reported. A radio-frequency model of a grating accelerator has been tested at Cornell, and extensive calculations compared with observations. Alternative structures consisting of either hemispherical bumps on a plane, or conducting spheres in space, have also been rf modeled. The use of liquid droplets to form such structures has been proposed and a conceptual design studied. Calculations and experiments have examined the effects of surface plasmas, and shown that in this case the reflectivity is low. However, calculations and observations suggest that gradients in excess of 1 GeV/meter should be obtainable without forming such plasma. An examination of wake fields shows that, with Landau damping, these are independent of wavelength. The use of near field structures to act as high gradient focusing elements has been studied and shows promise, independent of the acceleration mechanism. A proposal has been made to establish a facility that would enable ''proof of principle experiments'' to be performed on these and other laser driven accelerator mechanisms. 11 refs., 10 figs.

  11. Report of near field group

    International Nuclear Information System (INIS)

    Palmer, R.B.; Baggett, N.; Claus, J.

    1985-04-01

    Substantial progress since the Los Alamos Workshop two years ago is reported. A radio-frequency model of a grating accelerator has been tested at Cornell, and extensive calculations compared with observations. Alternative structures consisting of either hemispherical bumps on a plane, or conducting spheres in space, have also been rf modeled. The use of liquid droplets to form such structures has been proposed and a conceptual design studied. Calculations and experiments have examined the effects of surface plasmas, and shown that in this case the reflectivity is low. However, calculations and observations suggest that gradients in excess of 1 GeV/meter should be obtainable without forming such plasma. An examination of wake fields shows that, with Landau damping, these are independent of wavelength. The use of near field structures to act as high gradient focusing elements has been studied and shows promise, independent of the acceleration mechanism. A proposal has been made to establish a facility that would enable ''proof of principle experiments'' to be performed on these and other laser driven accelerator mechanisms. 11 refs., 10 figs

  12. Comparative assessment of five potential sites for hydrothermal magma systems: geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    White, A.F.

    1980-08-01

    A brief discussion is given of the geochemical objectives and questions that must be addressed in such an evaluation. A summary of the currently published literature that is pertinent in answering these questions is presented for each of the five areas: The Geysers-Clear Lake region, Long Valley, Rio Grand Rift, Roosevelt Hot Springs, and the Salton Trough. The major geochemical processes associated with proposed hydrothermal sites are categorized into three groups for presentation: geochemistry of magma and associated volcanic rocks, geochemistry of hydrothermal solutions, and geochemistry of hydrothermal alteration. (MHR)

  13. Ultra thin metallic coatings to control near field radiative heat transfer

    Science.gov (United States)

    Esquivel-Sirvent, R.

    2016-09-01

    We present a theoretical calculation of the changes in the near field radiative heat transfer between two surfaces due to the presence of ultra thin metallic coatings on semiconductors. Depending on the substrates, the radiative heat transfer is modulated by the thickness of the ultra thin film. In particular we consider gold thin films with thicknesses varying from 4 to 20 nm. The ultra-thin film has an insulator-conductor transition close to a critical thickness of dc = 6.4 nm and there is an increase in the near field spectral heat transfer just before the percolation transition. Depending on the substrates (Si or SiC) and the thickness of the metallic coatings we show how the near field heat transfer can be increased or decreased as a function of the metallic coating thickness. The calculations are based on available experimental data for the optical properties of ultrathin coatings.

  14. Near field heat transfer between random composite materials. Applications and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, Eva Yazmin; Esquivel-Sirvent, Raul [Univ. Nacional Autonoma de Mexico (Mexico). Inst. de Fisica

    2017-05-01

    We present a theoretical study of the limits and bounds of using effective medium approximations in the calculation of the near field radiative heat transfer between a composite system made of Au nanoparticles in a SiC host and an homogeneous SiC slab. The effective dielectric function of the composite slab is calculated using three different approximations: Maxwell-Garnett, Bruggeman, and Looyenga's. In addition, we considered an empirical fit to the effective dielectric function by Grundquist and Hunderi. We show that the calculated value of the heat flux in the near field is dependent on the model, and the difference in the effective dielectric function is larger around the plasmonic response of the Au nanoparticles. This, in turn, accounts for the difference in the near field radiative heat flux. For all values of filling fractions, the Looyenga approximation gives a lower bound for the heat flux.

  15. Electromagnetic Fields in Reverberant Environments

    NARCIS (Netherlands)

    Vogt-Ardatjew, Robert Andrzej

    2017-01-01

    The phenomenon of resonating electromagnetic (EM) fields has been commonly and successfully exploited in reverberation chambers (RC) for the purpose of electromagnetic compatibility (EMC) testing, as well as modeling multipath environments. Although largely successful, the currently used statistical

  16. Errors of first-order probe correction for higher-order probes in spherical near-field antenna measurements

    DEFF Research Database (Denmark)

    Laitinen, Tommi; Nielsen, Jeppe Majlund; Pivnenko, Sergiy

    2004-01-01

    An investigation is performed to study the error of the far-field pattern determined from a spherical near-field antenna measurement in the case where a first-order (mu=+-1) probe correction scheme is applied to the near-field signal measured by a higher-order probe.......An investigation is performed to study the error of the far-field pattern determined from a spherical near-field antenna measurement in the case where a first-order (mu=+-1) probe correction scheme is applied to the near-field signal measured by a higher-order probe....

  17. Near field acoustic holography with microphones on a rigid sphere

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Moreno-Pescador, Guillermo; Fernandez Grande, Efren

    2011-01-01

    Spherical near field acoustic holography (spherical NAH) is a technique that makes it possible to reconstruct the sound field inside and just outside a spherical surface on which the sound pressure is measured with an array of microphones. This is potentially very useful for source identification...

  18. [Design of flat field holographic concave grating for near-infrared spectrophotometer].

    Science.gov (United States)

    Xiang, Xian-Yi; Wen, Zhi-Yu

    2008-07-01

    Near-infrared spectrum analysis can be used to determine the nature or test quantitatively some chemical compositions by detecting molecular double frequency and multiple frequency absorption. It has been used in agriculture, biology, petrifaction, foodstuff, medicament, spinning and other fields. Near-infrared spectrophotometer is the main apparatus for near-infrared spectrum analysis, and the grating is the most important part of the apparatus. Based on holographic concave grating theory and optic design software CODE V, a flat field holographic concave grating for near-infrared spectrophotometer was designed from primary structure, which relied on global optimization of the software. The contradiction between wide spectrum bound and limited spectrum extension was resolved, aberrations were reduced successfully, spectrum information was utilized fully, and the optic structure of spectrometer was highly efficient. Using CODE V software, complex high-order aberration equations need not be solved, the result can be evaluated quickly, flat field and resolving power can be kept in balance, and the work efficiency is also enhanced. A paradigm of flat field holographic concave grating is given, it works between 900 nm to 1 700 nm, the diameter of the concave grating is 25 mm, and F/ # is 1. 5. The design result was analyzed and evaluated. It was showed that if the slit source, whose width is 50 microm, is used to reconstruction, the theoretic resolution capacity is better than 6.3 nm.

  19. Project-90 Near-field calculations using CALIBRE

    International Nuclear Information System (INIS)

    Worgan, K.; Robinson, P.

    1992-02-01

    A comprehensive set of near-field calculations for the Swedish Nuclear Power Inspectorates Project-90 safety assessment has been performed using the CALIBRE model. In the majority of cases considered the redox front migrates through the bentonite buffer and into the rock, where it becomes effectively immobilised. The fracture remains in a reducing state, which means that for solubility-limited nuclides, the concentration at the bentonite/fracture interface can never be greater than the reducing solubility limit. The calculations also show that significant retardation occurs for nuclides which are even moderately sorbed. The effect is less pronounced in the wider fracture and high flow cases, as the opportunity for diffusion from the fracture to the rock matrix is reduced. In contrast, the release from the near-field of poorly-sorbed nuclides which are not solubility limited is governed by the release rate from the fuel, the diffusive mass transfer resistance of the buffer, rock matrix and fracture, the initial inventories and the nuclide half-lives. In the reference case, the maximum dose potential of nuclides emerging from the near-field occur for I-129 and was 3.2 x 10 -7 Sv per canister-year, assuming the flux to be discharged directly into the wall receptor biosphere. The parameters which have the most impact on the reference base results are high flow, wide aperture and poor chemistry (i.e. high solubility limits and low sorption distribution coefficients). The effects of combining extreme values of parameters does not give results which are in proportion to their effect when applied in isolation. In the worst case variant (early canister failure high flow, wide aperture and poor chemistry) the maximum dose potential is 1.0 x 10 -4 Sv per canister-year, compared with 8.9 x 10 -6 Sv in the high flow case, 4.5 x 10 -7 in the wide aperture case, 2.3 x 10 -6 in the poor chemistry case and 3.9 x 10 -6 in the early failure, wide aperture and high flow case. (au)

  20. Panel discussion on near-field coupled processes with emphasis on performance assessment

    International Nuclear Information System (INIS)

    Codell, R.B.; Baca, R.G.; Ahola, M.P.

    1996-01-01

    The presentations in this panel discussion involve the general topic of near-field coupled processes and postclosure performance assessment with an emphasis on rock mechanics. The potential impact of near-field rock mass deformation on repository performance was discussed, as well as topics including long term excavation deterioration, the performance of geologic seals, and coupled processes concerning rock mechanics in performance assessments

  1. Fabrication of a novel nano-probe slide for near-field optical microscopy

    International Nuclear Information System (INIS)

    Yim, Sang-Youp; Jeang, Eun-Hee; Lee, Jae-Hoon; Park, Seung-Han; Cho, Kyu-Man

    2004-01-01

    A novel probe structure, which can act as a planar nano-probe slide for near-field microscopy, was proposed and fabricated. Sub-wavelength apertures on a Si substrate are successfully produced by means of standard photolithography techniques with properly selected masks. In particular, the anisotropic etching characteristics of Si substrate and the hardness of the Si 3 N 4 film are utilized. Probe-to-probe scanning of the fabricated near-field nano-probe slide shows sub-wavelength confinement of light and comparable throughput to the conventional optical fiber probe. We also show that the nano-probe slide can serve as a supporting base and a sub-wavelength aperture to obtain the near-field photoluminescence spectra of a limited number of CdSe nanocrystals.

  2. Near-field visualization of plasmonic lenses: an overall analysis of characterization errors

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2015-10-01

    Full Text Available Many factors influence the near-field visualization of plasmonic structures that are based on perforated elliptical slits. Here, characterization errors are experimentally analyzed in detail from both fabrication and measurement points of view. Some issues such as geometrical parameter, probe–sample surface interaction, misalignment, stigmation, and internal stress, have influence on the final near-field probing results. In comparison to the theoretical ideal case of near-field probing of the structures, numerical calculation is carried out on the basis of a finite-difference and time-domain (FDTD algorithm so as to support the error analyses. The analyses performed on the basis of both theoretical calculation and experimental probing can provide a helpful reference for the researchers probing their plasmonic structures and nanophotonic devices.

  3. Near-field light design with colloidal quantum dots for photonics and plasmonics.

    Science.gov (United States)

    Kress, Stephan J P; Richner, Patrizia; Jayanti, Sriharsha V; Galliker, Patrick; Kim, David K; Poulikakos, Dimos; Norris, David J

    2014-10-08

    Colloidal quantum-dots are bright, tunable emitters that are ideal for studying near-field quantum-optical interactions. However, their colloidal nature has hindered their facile and precise placement at desired near-field positions, particularly on the structured substrates prevalent in plasmonics. Here, we use high-resolution electro-hydrodynamic printing (quantum dots on both flat and structured substrates with a few nanometer precision. We also demonstrate that the autofocusing capability of the printing method enables placement of quantum dots preferentially at plasmonic hot spots. We exploit this control and design diffraction-limited photonic and plasmonic sources with arbitrary wavelength, shape, and intensity. We show that simple far-field illumination can excite these near-field sources and generate fundamental plasmonic wave-patterns (plane and spherical waves). The ability to tailor subdiffraction sources of plasmons with quantum dots provides a complementary technique to traditional scattering approaches, offering new capabilities for nanophotonics.

  4. Near-field circular polarization probed by chiral polyfluorene

    NARCIS (Netherlands)

    Savoini, M.; Biagioni, P.; Lakhwani, G.; Meskers, S.C.J.; Duò, L.; Finazzi, M.

    2009-01-01

    We demonstrate that a high degree of circular polarization can be delivered to the near field (NF) of an aperture at the apex of hollow-pyramid probes for scanning optical microscopy. This result is achieved by analyzing the dichroic properties of an annealed thin polymer film containing a chiral

  5. Near-field characterization of photonic crystal Y-splitters

    DEFF Research Database (Denmark)

    Volkov, V. S.; Bozhevolnyi, S. I.; Borel, Peter Ingo

    2005-01-01

    A scanning near-field optical microscope (SNOM) is used to directly map the propagation of light in a specially designed 50/50 photonic crystal (PC) Y-splitter fabricated on silicon-on-insulator (SOI) wafers. SNOM images are obtained for TE- and TM-polarized light in the wavelength range 1425...

  6. Near-to far-field transformation in the aperiodic Fourier modal method

    NARCIS (Netherlands)

    Rook, R.; Pisarenco, M.; Setija, I.D.

    2013-01-01

    This paper addresses the task of obtaining the far-field spectrum for a finite structure given the near-field calculated by the aperiodic Fourier modal method in contrast-field formulation (AFMM-CFF). The AFMM-CFF efficiently calculates the solution to Maxwell's equations for a finite structure by

  7. Organic geochemistry of deep ground waters and radionuclide-partitioning experiments under hydrothermal conditions

    International Nuclear Information System (INIS)

    Means, J.L.; Maest, A.S.; Crear, D.A.

    1983-07-01

    This report summarizes research on two separate tasks. In the first task, the organic geochemistry of groundwater samples from the Permian Basin of Texas, the Paradox Basin of Utah, and the Nevada Test Site has been characterized. Acidic compounds were derivatized and analyzed using gas chromatography-mass spectrometry, and the molecular weight characteristics of the organic constituents present were determined using dialysis and gel filtration chromatography. The total organic carbon contents of the groundwaters from the Permian and Paradox Basins are very high, ranging from 12 to 76 mg/l. Although the specific organic composition varies from aquifer to aquifer, the organic components of these groundwaters appear to be composed principally of low molecular weight polar compounds derived from local hydrocarbon deposits. The total organic carbon contents of the groundwaters from the Nevada Test Site are very low, ranging from 0.1 to 0.6 mg/l. Here the principal organic species appear to be humic compounds and low molecular weight fatty acids. In the second task the adsorption of certain radionuclides by geologic substrates has been measured in the presence and absence of organic complexing agents from 25 to 250 0 C. Major findings include the following: (a) in some cases the extent of adsorption of Sr, Co, and U actually increases with increasing temperature; (b) oxalic acid either has little effect on the adsorption or actually increases the adsorption of Cs and Sr by kaolinite, illite, and montmorillonite; (c) the thermal degradation of natural organic compounds in the near-field environment may be significant; and (d) the adsorption of U, Co, and Sr, and Cs onto kaolinite and montmorillonite reaches a steady state in less than an hour at 25 0 C, 1 atm. 10 figures, 4 tables

  8. The near-source impacts of diesel backup generators in urban environments

    Science.gov (United States)

    Tong, Zheming; Zhang, K. Max

    2015-05-01

    Distributed power generation, located close to consumers, plays an important role in the current and future power systems. However, its near-source impacts in complex urban environments are not well understood. In this paper, we focused on diesel backup generators that participate in demand response (DR) programs. We first improved the micro-environmental air quality simulations by employing a meteorology processor, AERMET, to generate site-specific boundary layer parameters for the Large Eddy Simulation (LES) modeling. The modeling structure was then incorporated into the CTAG model to evaluate the environmental impacts of diesel backup generators in near-source microenvironments. We found that the presence of either tall upwind or downwind building can deteriorate the air quality in the near-stack street canyons, largely due to the recirculation zones generated by the tall buildings, reducing the near-stack dispersion. Decreasing exhaust momentum ratio (stack exit velocity/ambient wind velocity) draws more exhaust into the recirculation zone, and reduces the effective stack height, which results in elevated near-ground concentrations inside downwind street canyons. The near-ground PM2.5 concentration for the worst scenarios could well exceed 100 μg m-3, posing potential health risk to people living and working nearby. In general, older diesel backup generators (i.e., Tier 1, 2 or older) without the up-to-date emission control may significantly increase the pollutant concentration in the near-source street canyons if participating in DR programs. Even generators that comply with Tier-4 standards could lead to PM hotspots if their stacks are next to tall buildings. Our study implies that the siting of diesel backup generators stacks should consider not only the interactions of fresh air intake and exhaust outlet for the building housing the backup generators, but also the dispersion of exhaust plumes in the surrounding environment.

  9. Near-field effects of asteroid impacts in deep water

    Energy Technology Data Exchange (ETDEWEB)

    Gisler, Galen R [Los Alamos National Laboratory; Weaver, Robert P [Los Alamos National Laboratory; Gittings, Michael L [Los Alamos National Laboratory

    2009-06-11

    Our previous work has shown that ocean impacts of asteroids below 500 m in diameter do not produce devastating long-distance tsunamis. Nevertheless, a significant portion of the ocean lies close enough to land that near-field effects may prove to be the greatest danger from asteroid impacts in the ocean. Crown splashes and central jets that rise up many kilometres into the atmosphere can produce, upon their collapse, highly non-linear breaking waves that could devastate shorelines within a hundred kilometres of the impact site. We present illustrative calculations, in two and three dimensions, of such impacts for a range of asteroid sizes and impact angles. We find that, as for land impacts, the greatest dangers from oceanic impacts are the short-term near-field, and long-term atmospheric effects.

  10. Reservoir Characterization using geostatistical and numerical modeling in GIS with noble gas geochemistry

    Science.gov (United States)

    Vasquez, D. A.; Swift, J. N.; Tan, S.; Darrah, T. H.

    2013-12-01

    The integration of precise geochemical analyses with quantitative engineering modeling into an interactive GIS system allows for a sophisticated and efficient method of reservoir engineering and characterization. Geographic Information Systems (GIS) is utilized as an advanced technique for oil field reservoir analysis by combining field engineering and geological/geochemical spatial datasets with the available systematic modeling and mapping methods to integrate the information into a spatially correlated first-hand approach in defining surface and subsurface characteristics. Three key methods of analysis include: 1) Geostatistical modeling to create a static and volumetric 3-dimensional representation of the geological body, 2) Numerical modeling to develop a dynamic and interactive 2-dimensional model of fluid flow across the reservoir and 3) Noble gas geochemistry to further define the physical conditions, components and history of the geologic system. Results thus far include using engineering algorithms for interpolating electrical well log properties across the field (spontaneous potential, resistivity) yielding a highly accurate and high-resolution 3D model of rock properties. Results so far also include using numerical finite difference methods (crank-nicholson) to solve for equations describing the distribution of pressure across field yielding a 2D simulation model of fluid flow across reservoir. Ongoing noble gas geochemistry results will also include determination of the source, thermal maturity and the extent/style of fluid migration (connectivity, continuity and directionality). Future work will include developing an inverse engineering algorithm to model for permeability, porosity and water saturation.This combination of new and efficient technological and analytical capabilities is geared to provide a better understanding of the field geology and hydrocarbon dynamics system with applications to determine the presence of hydrocarbon pay zones (or

  11. A multipurpose hybrid conventional/scanning near-field optical microscope for applications in materials science and biology

    International Nuclear Information System (INIS)

    Longo, G; Girasole, M; Pompeo, G; Generosi, R; Luce, M; Cricenti, A

    2010-01-01

    A hybrid conventional/scanning near-field optical microscope is presented. The instrument is obtained coupling an Olympus IX-70 inverted optical microscope with a SNOM head, to combine the versatility and ease of use of the conventional microscope with the high-resolution and three-dimensional reconstruction achieved by the SNOM. The head can be run in shear or tapping mode and is optimized to characterize soft, biological samples including living cells in physiological environment by including the SNOM in a cylindrical chamber that insulates it from external noise, while maintaining a controlled temperature and atmosphere

  12. Technetium-99 behavior in the terrestrial environment. Field observations and radiotracer experiments

    International Nuclear Information System (INIS)

    Tagami, Keiko

    2003-01-01

    Obtaining data on 99 Tc in the rice paddy field environment is important because Tc is a redox sensitive element. The behavior of Tc is expected to be different under upland field and rice paddy field conditions since the redox conditions in the soil environment differ. However, most of the data on the nuclide behavior in soil were obtained under upland field conditions. To understand the global fallout 99 Tc distributions in soil samples collected in Japan, a simple and rapid separation method was developed in order to determine low-levels of 99 Tc in soil samples by an inductively coupled plasma mass spectrometry. Also, radiotracer experiments using soils under aerobic and anaerobic conditions were carried out to clarify the Tc behavior under paddy field conditions. The results of determination of global fallout 99 Tc in Japanese soils indicated that the radionuclide had been accumulating in rice paddy fields. The mechanisms can be explained by the immobilization of Tc in soil under anaerobic conditions. From the radiotracer experiments, it was clear that under waterlogged conditions, the highly mobile TcO 4 - in soil was readily changed to other immobilized forms, such as TcO 2 , TcS 2 and organically bound forms. To this immobilization, the microbial activity seemed to have an important role in Tc sorption reactions. When the soil, which was once kept in anaerobic conditions, was air-dried again and kept in aerobic conditions, the chemical forms of immobilized Tc did not change remarkably. Interestingly, the similar Tc behavior was observed in a real wet forest near the Chernobyl Reactor. (author)

  13. Medieval land use management and geochemistry - spatial analyses on scales from households properties to whole fields systems

    Science.gov (United States)

    Horák, Jan; Janovský, Martin; Klír, Tomáš; Šmejda, Ladislav; Legut-Pintal, Maria

    2017-04-01

    We present the final or preliminary results of our researches of five villages: Spindelbach (Ore Mountains, North-Western Bohemia), Hol (near Prague, Central Bohemia), Lovětín and Regenholz (near Třešť, Czech-Moravian Upland) and Goschwitz (near Wroclaw, Poland). Our research is methodically based on broad spatial sampling of soil samples and mapping of basic soil conditions. We use XRF spectrometry as a main tool for multi-elemental analyses and as a tool for first step screening of large areas. The crucial factor of our methods is also a design of sampling based on a respect to historical land and land use features like parts of village field system or possesions of the households. Also macroscopic visual method of getting data and knowledge of the site is crucial. It was revealed that generally used and acknowledged human indicator - Phosphorus - can be present at only very low levels of concentration, or undetectable, even in the nearness of households. The natural conditions cannot be the causing factor at all cases. This situation is caused also by last human activity intensity and by its spatial manifestation. In such cases, multi-elemental analysis is very useful. Zinc is usually correlated with Phosphorus, which is also connected to Lead. The past human activity indicators are spatially usually connected to modern pollution indicators. These two inputs can be sometimes distinguished by statistical analyses and by spatial visualisation of data. Working with just concentrations can be misleading. Past land use management and its strategies were important for spatial distribution of soil geochemical indicators. Therefore, we can use them not only as quantifiers of human impact on nature, but we can also detect different management or knowledge and experience. As it was revealed e. g. by analyses of households` possessions differences. For example, generally presumed decreasing gradient of management intensity (e.g. manuring) along the distance from

  14. Near-field imaging of femtosecond laser ablated sub-λ/4 holes in lithium niobate

    International Nuclear Information System (INIS)

    Rodenas, Airan; Lamela, Jorge; Jaque, Daniel; Lifante, Gines; Jaque, Francisco; Garcia-Martin, Antonio; Zhou Guangyong; Gu Min

    2009-01-01

    We report on the direct femtosecond laser ablation of sub-λ/4 (80-250 nm) holes in LiNbO 3 crystals and on its local near-field imaging. We show that the near-field transmission of holes can feature an attenuation of ∼75% at hole central position, and a ∼20% transmission enhancement at its sides. This high-contrast ring-shaped near-field distribution is found to be in agreement with simulations, suggesting the surface relief as the main contrast mechanism.

  15. Far- and near-field second-harmonic imaging of ferroelectric domain walls

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Pedersen, K.; Skettrup, Torben

    1998-01-01

    Domain walls in periodically poled ferroelectric LiNbO3 crystals are observed with both far- and near-field imaging techniques that make use of second harmonic generation in the transition regions between neighbouring domains. Second harmonic images of domain walls represent bright lines of about.......5 micrometers in width (as measured with the near-field microscope) for the polarization of the second harmonic radiation perpendicular to the domain walls. Origin and selection rules for the constrast in second harmonic images of domain walls are discussed....

  16. Polarization contrast in reflection near-field optical microscopy with uncoated fibre tips

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Langbein, Wolfgang; Hvam, Jørn Märcher

    1999-01-01

    Using cross-hatched, patterned semiconductor surfaces and round 20-nm-thick gold pads on semiconductor wafers, we investigate the imaging characteristics of a reflection near-field optical microscope with an uncoated fibre tip for different polarization configurations and light wavelengths....... Is is shown that cross-polarized detection allows one to effectively suppress far-field components in the detected signal and to realise imaging of optical contrast on the sub-wavelength scale. The sensitivity window of our microscope, i.e. the scale on which near-field optical images represent mainly optical...

  17. Group velocity measurement using spectral interference in near-field scanning optical microscopy

    International Nuclear Information System (INIS)

    Mills, John D.; Chaipiboonwong, Tipsuda; Brocklesby, William S.; Charlton, Martin D. B.; Netti, Caterina; Zoorob, Majd E.; Baumberg, Jeremy J.

    2006-01-01

    Near-field scanning optical microscopy provides a tool for studying the behavior of optical fields inside waveguides. In this experiment the authors measure directly the variation of group velocity between different modes of a planar slab waveguide as the modes propagate along the guide. The measurement is made using the spectral interference between pulses propagating inside the waveguide with different group velocities, collected using a near-field scanning optical microscope at different points down the guide and spectrally resolved. The results are compared to models of group velocities in simple guides

  18. A comparison of inverse boundary element method and near-field acoustical holography

    DEFF Research Database (Denmark)

    Schuhmacher, Andreas; Hald, Jørgen; Saemann, E.-U.

    1999-01-01

    An inverse boundary element method (IBEM) is used to estimate the surface velocity of a rolling tyre from measurements of the near-field pressure. Subsequently, the sound pressure is calculated over a finite plane surface next to the tyre from the reconstructed velocity field on the tyre surface........ In order to verify the reconstruction process, part of the measurement data is used together with Near-Field Acoustical Holography (NAH). Estimated distributions of sound pressure and particle velocity over a plane surface obtained from the two methods are compared....

  19. Optical measurement of acoustic radiation pressure of the near-field acoustic levitation through transparent object

    OpenAIRE

    Nakamura, Satoshi; Furusawa, Toshiaki; Sasao, Yasuhiro; Katsura, Kogure; Naoki, Kondo

    2013-01-01

    It is known that macroscopic objects can be levitated for few to several hundred micrometers by near-field acoustic field and this phenomenon is called near-field acoustic levitation (NFAL). Although there are various experiments conducted to measure integrated acoustic pressure on the object surface, up to now there was no direct method to measure pressure distribution. In this study we measured the acoustic radiation pressure of the near-field acoustic levitation via pressure-sensitive paint.

  20. Optical near-field studies of waveguiding organic nanofibers by angular dependent excitation

    DEFF Research Database (Denmark)

    Maibohm, Christian

    .                    2) Institute of General Physics, Russian Academy of Science, 119991 Moscow, Russia. Abstract:   Single crystalline organic nanofibers of para-phenylene are grown in UHV by MBE and dipole assisted self-assembly. In the optical far-field the fluorescence from a single nanofiber is spectrally well...... defined and highly polarized. By UV excitation in a fluorescence microscope it has also been shown that nanofibers have waveguiding properties. To further characterize the waveguiding properties the optical near-field has to be investigated. This is done by transferring nanofibers to an quartz half sphere...... where they are excited by the evanescent wave from a total internal reflected UV laser. The optical near-field is probed by the fiber tip of a SNOM (scanning near-field optical microscope). In the setup it is possible to change the angle of incidence of the excitation laser i.e. change the k...

  1. High-density near-field optical disc recording using phase change media and polycarbonate substrate

    Science.gov (United States)

    Shinoda, Masataka; Saito, Kimihiro; Ishimoto, Tsutomu; Kondo, Takao; Nakaoki, Ariyoshi; Furuki, Motohiro; Takeda, Minoru; Akiyama, Yuji; Shimouma, Takashi; Yamamoto, Masanobu

    2004-09-01

    We developed a high density near field optical recording disc system with a solid immersion lens and two laser sources. In order to realize the near field optical recording, we used a phase change recording media and a molded polycarbonate substrate. The near field optical pick-up consists of a solid immersion lens with numerical aperture of 1.84. The clear eye pattern of 90.2 GB capacity (160nm track pitch and 62 nm per bit) was observed. The jitter using a limit equalizer was 10.0 % without cross-talk. The bit error rate using an adaptive PRML with 8 taps was 3.7e-6 without cross-talk. We confirmed that the near field optical disc system is a promising technology for a next generation high density optical disc system.

  2. Near-field solubility studies

    International Nuclear Information System (INIS)

    Thomason, H.P.; Williams, S.J.

    1992-02-01

    Experimental determinations of the solubilities of americium, plutonium, neptunium, protactinium, thorium, radium, lead, tin, palladium and zirconium are reported. These elements have radioactive isotopes of concern in assessments of radioactive waste disposal. All measurements were made under the highly alkaline conditions typical of the near field of a radioactive waste repository which uses cementitious materials for many of the immobilisation matrices, the backfill and the engineered structures. Low redox potentials, typical of those resulting from the corrosion of iron and steel, were simulated for those elements having more than one accessible oxidation state. The dissolved concentrations of the elements were defined using ultrafiltration. In addition, the corrosion of iron and stainless steel was shown to generate low redox potentials in solution and the solubility of iron(II) at high pH was measured and found to be sufficient for it to act as a redox buffer with respect to neptunium and plutonium. (author)

  3. Enhanced energy transfer by near-field coupling of a nanostructured metamaterial with a graphene-covered plate

    International Nuclear Information System (INIS)

    Chang, Jui-Yung; Yang, Yue; Wang, Liping

    2016-01-01

    Coupled surface plasmon/phonon polaritons and hyperbolic modes are known to enhance radiative transfer across nanometer vacuum gaps but usually require identical materials. It becomes crucial to achieve strong near-field energy transfer between dissimilar materials for applications like near-field thermophotovoltaic and thermal rectification. In this work, we theoretically demonstrate enhanced near-field radiative transfer between a nanostructured metamaterial emitter and a graphene-covered planar receiver. Strong near-field coupling with two orders of magnitude enhancement in the spectral heat flux is achieved at the gap distance of 20 nm. By carefully selecting the graphene chemical potential and doping levels of silicon nanohole emitter and silicon plate receiver, the total near-field radiative heat flux can reach about 500 times higher than the far-field blackbody limit between 400 K and 300 K. The physical mechanism is elucidated by the near-field surface plasmon coupling with fluctuational electrodynamics and dispersion relations. The effects of graphene chemical potential, emitter and receiver doping levels, and vacuum gap distance on the near-field coupling and radiative energy transfer are analyzed in detail. - Highlights: • Near-field radiative transfer between a metamaterial and a graphene-covered plate is studied. • Effective medium theory with uniaxial optics is employed to model nanohole metamaterials. • Enhancement by 2 orders is found between dissimilar materials with graphene coating. • Extraordinary coupling of the nanostructured emitter with graphene is elucidated. • Effects of doping level of silicon and graphene chemical potential are investigated.

  4. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2005-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeoclimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. (author). 52 refs., 11 figs., 2 tabs

  5. A New Method for Analyzing Near-Field Faraday Probe Data in Hall Thrusters

    Science.gov (United States)

    Huang, Wensheng; Shastry, Rohit; Herman, Daniel A.; Soulas, George C.; Kamhawi, Hani

    2013-01-01

    This paper presents a new method for analyzing near-field Faraday probe data obtained from Hall thrusters. Traditional methods spawned from far-field Faraday probe analysis rely on assumptions that are not applicable to near-field Faraday probe data. In particular, arbitrary choices for the point of origin and limits of integration have made interpretation of the results difficult. The new method, called iterative pathfinding, uses the evolution of the near-field plume with distance to provide feedback for determining the location of the point of origin. Although still susceptible to the choice of integration limits, this method presents a systematic approach to determining the origin point for calculating the divergence angle. The iterative pathfinding method is applied to near-field Faraday probe data taken in a previous study from the NASA-300M and NASA-457Mv2 Hall thrusters. Since these two thrusters use centrally mounted cathodes the current density associated with the cathode plume is removed before applying iterative pathfinding. A procedure is presented for removing the cathode plume. The results of the analysis are compared to far-field probe analysis results. This paper ends with checks on the validity of the new method and discussions on the implications of the results.

  6. Geology and geochemistry of the Atacama Desert.

    Science.gov (United States)

    Tapia, J; González, R; Townley, B; Oliveros, V; Álvarez, F; Aguilar, G; Menzies, A; Calderón, M

    2018-02-14

    The Atacama Desert, the driest of its kind on Earth, hosts a number of unique geological and geochemical features that make it unlike any other environment on the planet. Considering its location on the western border of South America, between 17 and 28 °S, its climate has been characterized as arid to hyperarid for at least the past 10 million years. Notably dry climatic conditions of the Atacama Desert have been related to uplift of the Andes and are believed to have played an important role in the development of the most distinctive features of this desert, including: (i) nitrates and iodine deposits in the Central Depression, (ii) secondary enrichment in porphyry copper deposits in the Precordillera, (iii) Li enrichment in salt flats of the Altiplano, and (iv) life in extreme habitats. The geology and physiography of the Atacama Desert have been largely shaped by the convergent margin present since the Mesozoic era. The geochemistry of surface materials is related to rock geochemistry (Co, Cr, Fe, Mn, V, and Zn), salt flats, and evaporite compositions in endorheic basins (As, B, and Li), in addition to anthropogenic activities (Cu, Mo, and Pb). The composition of surface water is highly variable, nonetheless in general it presents a circumneutral pH with higher conductivity and total dissolved solids in brines. Major water constituents, with the exception of HCO 3 - , are generally related to the increase of salinity, and despite the fact that trace elements are not well-documented, surface waters of the Atacama Desert are enriched in As, B, and Li when compared to the average respective concentrations in rivers worldwide.

  7. Natural geochemical analogues of the near field of high-level nuclear waste repositories

    International Nuclear Information System (INIS)

    Apps, J.A.

    1995-01-01

    United States practice has been to design high-level nuclear waste (HLW) geological repositories with waste densities sufficiently high that repository temperatures surrounding the waste will exceed 100 degrees C and could reach 250 degrees C. Basalt and devitrified vitroclastic tuff are among the host rocks considered for waste emplacement. Near-field repository thermal behavior and chemical alteration in such rocks is expected to be similar to that observed in many geothermal systems. Therefore, the predictive modeling required for performance assessment studies of the near field could be validated and calibrated using geothermal systems as natural analogues. Examples are given which demonstrate the need for refinement of the thermodynamic databases used in geochemical modeling of near-field natural analogues and the extent to which present models can predict conditions in geothermal fields

  8. A novel phase-sensitive scanning near-field optical microscope

    International Nuclear Information System (INIS)

    Wu Xiao-Yu; Lin Sun; Tan Qiao-Feng; Wang Jia

    2015-01-01

    Phase is one of the most important parameters of electromagnetic waves. It is the phase distribution that determines the propagation, reflection, refraction, focusing, divergence, and coupling features of light, and further affects the intensity distribution. In recent years, the designs of surface plasmon polariton (SPP) devices have mostly been based on the phase modulation and manipulation. Here we demonstrate a phase sensitive multi-parameter heterodyne scanning near-field optical microscope (SNOM) with an aperture probe in the visible range, with which the near field optical phase and amplitude distributions can be simultaneously obtained. A novel architecture combining a spatial optical path and a fiber optical path is employed for stability and flexibility. Two kinds of typical nano-photonic devices are tested with the system. With the phase-sensitive SNOM, the phase and amplitude distributions of any nano-optical field and localized field generated with any SPP nano-structures and irregular phase modulation surfaces can be investigated. The phase distribution and the interference pattern will help us to gain a better understanding of how light interacts with SPP structures and how SPP waves generate, localize, convert, and propagate on an SPP surface. This will be a significant guidance on SPP nano-structure design and optimization. (paper)

  9. Geochemistry of actinides and fission products in natural aquifer systems

    International Nuclear Information System (INIS)

    Kim, J.I.

    1989-06-01

    The progress in the research area of the community project MIRAGE: 'Geochemistry of actinides and fission products in natural aquatic systems' has been reviewed. This programme belongs to a specific research and technical development programme for the European Atomic Energy Community in the field of management and storage of radioactive waste. The review summarizes research progresses in subject areas: complexation with organics, colloid generation in groundwater and basic retention mechanisms in the framework of the migration of radionuclides in the geosphere. The subject areas are being investigated by 23 laboratories under interlaboratory collaborations or independent studies. (orig.)

  10. Thermodynamic modelling of bentonite-groundwater interaction and implications for near field chemistry in a repository for spent fuel

    International Nuclear Information System (INIS)

    Wanner, H.; Wersin, P.; Sierro, N.

    1992-11-01

    Predictions of near field geochemistry are made using a thermodynamic model for bentonite/ground interaction. This model is a refinement and extension of the model developed by the senior author. It is based on recent experiments performed at high solid/water ratio and adapted to the Swedish type of HLW repository design. Thus, from the obtained experimental results on solution composition, the model includes chemical reactions resulting from both the impurities and the main clay fraction within the bentonite. Ion exchange reactions are treated both with and without the contribution of edge sites. Due to its thermodynamic basis, the model exhibits prediction capability over a wide range of conditions in terms of solid/water ratio. The modelling of repository conditions implies, due to the lack of experimental information, simplifications with regard to thermodynamic properties of the bentonite. This mainly involves the non-consideration of the temperature effects and of the acid/base properties of the solid. Nevertheless, our results yield insight into important processes affecting porewater chemistry. Thus, the model suggests that proton exchange reactions may exert a strong control on calcite dissolution within highly compacted bentonite. Estimations of chemical changes over time in the bentonite were done in the basis of a mixing tank model. These results indicate transformation of Na-bentonite to Ca-bentonite over time. The extent of this process, however, critically depends on the amount of carbonate present in the bentonite. (authors) (34 refs.)

  11. Study on the system development for evaluating long-term alteration of hydraulic field in near field

    International Nuclear Information System (INIS)

    Okutu, Kazuo; Morikawa, Seiji; Takamura, Hisashi

    2002-02-01

    For the high performance evaluation of reliability of TRU waste repository, the system development for evaluating long-term alteration in consideration of the changes action of barrier materials of hydraulic field in Near Field is required. In this research, system development for evaluating long-term alteration of hydraulic field in Near Field was examined. Examination of the basic specification of chemical/dynamic alteration action analysis system used as the composition element of this system and a whole system were performed. The research result of this year is shown below. 1) The system by which the chemical changes happened by Near Field as influence of the exudation liquid from cement material are evaluated was examined. In this year, document investigation about the various processes about chemical alteration and extraction of a choice, presentation of the uncertainty about a model or data, preliminary modeling, a simple analysis tool creation and sensitivity analysis, extraction of the process which should be taken into consideration in a system valuation modeling and a phenomenon analysis model, and a corresponding mathematics model, optimization of the software composition for development of a system valuation modeling, the exercise by the preliminary system analysis model, the experiment plan for the corroboration of a model were shown. 2) In consideration of change of the physical characteristic accompanying chemical alteration of bentonite material and cement material, the system by which dynamic changes action of repository is evaluated was examined. In this year, arrangement of the dynamics action of repository for long-term were shown. Extraction of a phenomenon made applicable to evaluation was shown. And the dynamic models were investigated and the prototype of the dynamics model that can take into consideration the characteristic of bentonite material was shown. And the basic composition of a dynamic changes action analysis system was shown. 3

  12. Transfer functions in collection scanning near-field optical microscopy

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Vohnsen, Brian; Bozhevolnaya, Elena A.

    1999-01-01

    are considered with respect to the relation between near-field optical images and the corresponding intensity distributions. Our conclusions are supported with numerical simulations and experimental results obtained by using a photon scanning tunneling microscope with an uncoated fiber tip....

  13. Progress in nano-electro optics characterization of nano-optical materials and optical near-field interactions

    CERN Document Server

    Ohtsu, Motoichi

    2005-01-01

    This volume focuses on the characterization of nano-optical materials and optical-near field interactions. It begins with the techniques for characterizing the magneto-optical Kerr effect and continues with methods to determine structural and optical properties in high-quality quantum wires with high spatial uniformity. Further topics include: near-field luminescence mapping in InGaN/GaN single quantum well structures in order to interpret the recombination mechanism in InGaN-based nano-structures; and theoretical treatment of the optical near field and optical near-field interactions, providing the basis for investigating the signal transport and associated dissipation in nano-optical devices. Taken as a whole, this overview will be a valuable resource for engineers and scientists working in the field of nano-electro-optics.

  14. Investigation of acoustic field near to elastic thin plate using integral method

    Directory of Open Access Journals (Sweden)

    В.І. Токарев

    2004-01-01

    Full Text Available  Investigation of acoustic field near to elastic thin plate using  integral method The influence of boundary conditions on sound wave propagation, radiation and transmission through thin elastic plate is investigated. Necessary for that numerical model was found using the Helmholtz equation and equation of oscilated plate by means of integral formulation of the solution for acoustic fields near to elastic thin plate and for bending waves of small amplitudes.

  15. Kinetic model for electric-field induced point defect redistribution near semiconductor surfaces

    Science.gov (United States)

    Gorai, Prashun; Seebauer, Edmund G.

    2014-07-01

    The spatial distribution of point defects near semiconductor surfaces affects the efficiency of devices. Near-surface band bending generates electric fields that influence the spatial redistribution of charged mobile defects that exchange infrequently with the lattice, as recently demonstrated for pile-up of isotopic oxygen near rutile TiO2 (110). The present work derives a mathematical model to describe such redistribution and establishes its temporal dependence on defect injection rate and band bending. The model shows that band bending of only a few meV induces significant redistribution, and that the direction of the electric field governs formation of either a valley or a pile-up.

  16. Kinetic model for electric-field induced point defect redistribution near semiconductor surfaces

    International Nuclear Information System (INIS)

    Gorai, Prashun; Seebauer, Edmund G.

    2014-01-01

    The spatial distribution of point defects near semiconductor surfaces affects the efficiency of devices. Near-surface band bending generates electric fields that influence the spatial redistribution of charged mobile defects that exchange infrequently with the lattice, as recently demonstrated for pile-up of isotopic oxygen near rutile TiO 2 (110). The present work derives a mathematical model to describe such redistribution and establishes its temporal dependence on defect injection rate and band bending. The model shows that band bending of only a few meV induces significant redistribution, and that the direction of the electric field governs formation of either a valley or a pile-up.

  17. Near-field marking of gold nanostars by ultrashort pulsed laser irradiation: experiment and simulations

    Science.gov (United States)

    Møller, Søren H.; Vester-Petersen, Joakim; Nazir, Adnan; Eriksen, Emil H.; Julsgaard, Brian; Madsen, Søren P.; Balling, Peter

    2018-02-01

    Quantitative measurements of the electric near-field distribution of star-shaped gold nanoparticles have been performed by femtosecond laser ablation. Measurements were carried out on and off the plasmon resonance. A detailed comparison with numerical simulations of the electric fields is presented. Semi-quantitative agreement is found, with slight systematic differences between experimentally observed and simulated near-field patterns close to strong electric-field gradients. The deviations are attributed to carrier transport preceding ablation.

  18. Rydberg excitation of neutral nitric oxide molecules in strong UV and near-IR laser fields

    International Nuclear Information System (INIS)

    Lv Hang; Zhang Jun-Feng; Zuo Wan-Long; Xu Hai-Feng; Jin Ming-Xing; Ding Da-Jun

    2015-01-01

    Rydberg state excitations of neutral nitric oxide molecules are studied in strong ultraviolet (UV) and near-infra-red (IR) laser fields using a linear time-of-flight (TOF) mass spectrometer with the pulsed electronic field ionization method. The yield of Rydberg molecules is measured as a function of laser intensity and ellipticity, and the results in UV laser fields are compared with those in near-IR laser fields. The present study provides the first experimental evidence of neutral Rydberg molecules surviving in a strong laser field. The results indicate that a rescattering-after-tunneling process is the main contribution to the formation of Rydberg molecules in strong near-IR laser fields, while multi-photon excitation may play an important role in the strong UV laser fields. (paper)

  19. Imaging Brain Function with Functional Near-Infrared Spectroscopy in Unconstrained Environments

    Directory of Open Access Journals (Sweden)

    Joana B. Balardin

    2017-05-01

    Full Text Available Assessing the neural correlates of motor and cognitive processes under naturalistic experimentation is challenging due to the movement constraints of traditional brain imaging technologies. The recent advent of portable technologies that are less sensitive to motion artifacts such as Functional Near Infrared Spectroscopy (fNIRS have been made possible the study of brain function in freely-moving participants. In this paper, we describe a series of proof-of-concept experiments examining the potential of fNIRS in assessing the neural correlates of cognitive and motor processes in unconstrained environments. We show illustrative applications for practicing a sport (i.e., table tennis, playing a musical instrument (i.e., piano and violin alone or in duo and performing daily activities for many hours (i.e., continuous monitoring. Our results expand upon previous research on the feasibility and robustness of fNIRS to monitor brain hemodynamic changes in different real life settings. We believe that these preliminary results showing the flexibility and robustness of fNIRS measurements may contribute by inspiring future work in the field of applied neuroscience.

  20. Scanning Near-Field Optical Microscopy

    Directory of Open Access Journals (Sweden)

    Dušan Vobornik

    2008-02-01

    Full Text Available An average human eye can see details down to 0,07 mm in size. The ability to see smaller details of the matter is correlated with the development of the science and the comprehension of the nature. Today’s science needs eyes for the nano-world. Examples are easily found in biology and medical sciences. There is a great need to determine shape, size, chemical composition, molecular structure and dynamic properties of nano-structures. To do this, microscopes with high spatial, spectral and temporal resolution are required. Scanning Near-field Optical Microscopy (SNOM is a new step in the evolution of microscopy. The conventional, lens-based microscopes have their resolution limited by diffraction. SNOM is not subject to this limitation and can offer up to 70 times better resolution.

  1. Scanning near-field optical microscopy.

    Science.gov (United States)

    Vobornik, Dusan; Vobornik, Slavenka

    2008-02-01

    An average human eye can see details down to 0,07 mm in size. The ability to see smaller details of the matter is correlated with the development of the science and the comprehension of the nature. Today's science needs eyes for the nano-world. Examples are easily found in biology and medical sciences. There is a great need to determine shape, size, chemical composition, molecular structure and dynamic properties of nano-structures. To do this, microscopes with high spatial, spectral and temporal resolution are required. Scanning Near-field Optical Microscopy (SNOM) is a new step in the evolution of microscopy. The conventional, lens-based microscopes have their resolution limited by diffraction. SNOM is not subject to this limitation and can offer up to 70 times better resolution.

  2. Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, Kenneth E; Haller, Merrick C; Ozkan-Haller, H Tuba

    2013-01-26

    This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array of newly developed Buoys' that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate

  3. Optical detection of ultrasound using an apertureless near-field scanning optical microscopy system

    Science.gov (United States)

    Ahn, Phillip; Zhang, Zhen; Sun, Cheng; Balogun, Oluwaseyi

    2013-01-01

    Laser ultrasonics techniques are power approaches for non-contact generation and detection of high frequency ultrasound on a local scale. In these techniques, optical diffraction limits the spatial information that can be accessed from a measurement. In order to improve the lateral spatial resolution, we incorporate an apertureless near-field scanning optical microscope (aNSOM) into laser ultrasonics setup for local detection of laser generated ultrasound. The aNSOM technique relies on the measurement of a weak backscattered near-field light intensity resulting from the oblique illumination of a nanoscale probe-tip positioned close to a sample surface. We enhance the optical near-field intensity by coupling light to surface plasmon polaritons (SPPs) on the shaft of an atomic force microscopy (AFM) cantilever. The SPPs propagate down the AFM shaft, localize at the tip apex, and are backscattered to the far-field when the separation distance between the probe tip and the sample surface is comparable to the probe-tip radius. The backscattered near-field intensity is dynamically modulated when an ultrasonic wave arrives at the sample surface leading to a transient change in the tip-sample separation distance. We present experimental results detailing measurement of broadband and narrowband laser generated ultrasound in solids with frequencies reaching up to 180 MHz range.

  4. Selected Water-Quality Data from the Cedar River and Cedar Rapids Well Fields, Cedar Rapids, Iowa, 1999-2005

    Science.gov (United States)

    Littin, Gregory R.; Schnoebelen, Douglas J.

    2010-01-01

    The Cedar River alluvial aquifer is the primary source of municipal water in the Cedar Rapids, Iowa area. Municipal wells are completed in the alluvial aquifer at approximately 40 to 80 feet deep. The City of Cedar Rapids and the U.S. Geological Survey have been conducting a cooperative study of the groundwater-flow system and water quality near the well fields since 1992. Previous cooperative studies between the City of Cedar Rapids and the U.S. Geological Survey have documented hydrologic and water-quality data, geochemistry, and groundwater models. Water-quality samples were collected for studies involving well field monitoring, trends, source-water protection, groundwater geochemistry, evaluation of surface and ground-water interaction, assessment of pesticides in groundwater and surface water, and to evaluate water quality near a wetland area in the Seminole well field. Typical water-quality analyses included major ions (boron, bromide, calcium, chloride, fluoride, iron, magnesium, manganese, potassium, silica, sodium, and sulfate), nutrients (ammonia as nitrogen, nitrite as nitrogen, nitrite plus nitrate as nitrogen, and orthophosphate as phosphorus), dissolved organic carbon, and selected pesticides including two degradates of the herbicide atrazine. In addition, two synoptic samplings included analyses of additional pesticide degradates in water samples. Physical field parameters (alkalinity, dissolved oxygen, pH, specific conductance and water temperature) were recorded with each water sample collected. This report presents the results of water quality data-collection activities from January 1999 through December 2005. Methods of data collection, quality-assurance samples, water-quality analyses, and statistical summaries are presented. Data include the results of water-quality analyses from quarterly and synoptic sampling from monitoring wells, municipal wells, and the Cedar River.

  5. Near-field thermal radiation between hyperbolic metamaterials: Graphite and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X. L.; Zhang, R. Z.; Zhang, Z. M., E-mail: zhuomin.zhang@me.gatech.edu [G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2013-11-18

    The near-field radiative heat transfer for two hyperbolic metamaterials, namely, graphite and vertically aligned carbon nanotubes (CNTs), is investigated. Graphite is a naturally existing uniaxial medium, while CNT arrays can be modeled as an effective anisotropic medium. Different hyperbolic modes can be separately supported by these materials in certain infrared regions, resulting in a strong enhancement in near-field heat transfer. It is predicted that the heat flux between two CNT arrays can exceed that between SiC plates at any vacuum gap distance and is about 10 times higher with a 10 nm gap.

  6. Nanospectrofluorometry inside single living cell by scanning near-field optical microscopy

    Science.gov (United States)

    Lei, F. H.; Shang, G. Y.; Troyon, M.; Spajer, M.; Morjani, H.; Angiboust, J. F.; Manfait, M.

    2001-10-01

    Near-field fluorescence spectra with subdiffraction limit spatial resolution have been taken in the proximity of mitochondrial membrane inside breast adenocarcinoma cells (MCF7) treated with the fluorescent dye (JC-1) by using a scanning near-field optical microscope coupled with a confocal laser microspectrofluorometer. The probe-sample distance control is based on a piezoelectric bimorph shear force sensor having a static spring constant k=5 μN/nm and a quality factor Q=40 in a physiological medium of viscosity η=1.0 cp. The sensitivity of the force sensor has been tested by imaging a MCF7 cell surface.

  7. Graphene-assisted near-field radiative heat transfer between corrugated polar materials

    International Nuclear Information System (INIS)

    Liu, X. L.; Zhang, Z. M.

    2014-01-01

    Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

  8. Evaluation of long-term mechanical stability of near field

    International Nuclear Information System (INIS)

    Takaji, Kazuhiko; Sugino, Hiroyuki; Okutsu, Kazuo; Miura, Kazuhiko; Tabei, Kazuto; Noda, Masaru; Takahashi, Shinichi; Sugie, Shigehiko

    1999-11-01

    In the near field, as tunnels and pits are excavated, a redistribution of stresses in the surrounding rock will occur. For a long period of time after the emplacement of waste packages various events will take place, such as the swelling of the buffer, sinking of the overpack under its own weight, deformation arising from expansion of overpack corrosion products and the creep deformation of the rock mass. The evaluation of what effects these changes in the stress-state will have on the buffer and rock mass is a major issue from the viewpoint of safety assessment. Therefore, rock creep analysis, overpack corrosion expansion analysis and overpack sinking analysis have been made in order to examine the long-term mechanical stability of the near field and the interaction of various events that may affect the stability of the near field over a long period of time. As the results, rock creep behavior, the variations of the stress-state and the range of the influence zone differ from the rock strength, strength of buffer in the tunnel and side pressure coefficient etc. about the hard rock system and soft rock system established as basic cases. And the magnitude of the stress variations for buffer by the overpack sinking and rock creep deformation is negligible compared with it by the overpack corrosion expansion. Furthermore, though very limited zone of buffer around the overpack is close to the critical state by the overpack corrosion expansion, the engineered barrier system attains a comparatively stable state for a long period of time. (author)

  9. Single molecule mapping of the optical field distribution of probes for near-field microscopy

    NARCIS (Netherlands)

    Veerman, J.A.; Garcia Parajo, M.F.; Kuipers, L.; van Hulst, N.F.

    1999-01-01

    The most difficult task in near-field scanning optical microscopy (NSOM) is to make a high quality subwavelength aperture probe, Recently we have developed high definition NSOM probes by focused ion beam (FIB) milling. These probes have a higher brightness, better polarization characteristics,

  10. Effects of a power and photon energy of incident light on near-field etching properties

    Science.gov (United States)

    Yatsui, T.; Saito, H.; Nishioka, K.; Leuschel, B.; Soppera, O.; Nobusada, K.

    2017-12-01

    We developed a near-field etching technique for realizing an ultra-flat surfaces of various materials and structures. To elucidate the near-field etching properties, we have investigated the effects of power and the photon energy of the incident light. First, we established theoretically that an optical near-field with photon energy lower than the absorption edge of the molecules can induce molecular vibrations. We used nanodiamonds to study the power dependence of the near-field etching properties. From the topological changes of the nanodiamonds, we confirmed the linear-dependence of the etching volume with the incident power. Furthermore, we studied the photon energy dependence using TiO2 nanostriped structures, which revealed that a lower photon energy results in a lower etching rate.

  11. Modeling of the near field plume of a Hall thruster

    International Nuclear Information System (INIS)

    Boyd, Iain D.; Yim, John T.

    2004-01-01

    In this study, a detailed numerical model is developed to simulate the xenon plasma near-field plume from a Hall thruster. The model uses a detailed fluid model to describe the electrons and a particle-based kinetic approach is used to model the heavy xenon ions and atoms. The detailed model is applied to compute the near field plume of a small, 200 W Hall thruster. Results from the detailed model are compared with the standard modeling approach that employs the Boltzmann model. The usefulness of the model detailed is assessed through direct comparisons with a number of different measured data sets. The comparisons illustrate that the detailed model accurately predicts a number of features of the measured data not captured by the simpler Boltzmann approach

  12. Near Field Communication: Technology and Market Trends

    Directory of Open Access Journals (Sweden)

    Gabriella Arcese

    2014-09-01

    Full Text Available Among the different hi-tech content domains, the telecommunications industry is one of the most relevant, in particular for the Italian economy. Moreover, Near Field Communication (NFC represents an example of innovative production and a technological introduction in the telecommunications context. It has a threefold function: card emulator, peer-to-peer communication and digital content access, and it could be pervasively integrated in many different domains, especially in the mobile payment one. The increasing attention on NFC technology from the academic community has improved an analysis on the changes and the development perspective about mobile payments. It has considered the work done by the GSMA (Global System for Mobile Communications Association and the NFC Forum in recent years. This study starts from an analysis of the scientific contributions to Near Field Communication and how the main researches on this topic were conceived. Our focus is on the diffusion rates, the adoption rates and the technology life cycle. After that, we analyze the technical-economical elements of NFC. Finally, this work presents the state of art of the improvements to this technology with a deeper focus on NFC technologies applied to the tourism industry. In this way, we have done a case analysis that shows some of the NFC existent applications linked to each stage of the tourism value chain.

  13. Organic geochemistry of Czech amber

    Czech Academy of Sciences Publication Activity Database

    Havelcová, Martina; Sýkorová, Ivana; Mach, K.; Dvořák, Z.

    2015-01-01

    Roč. 11, č. 1 (2015), s. 146 ISSN 1336-7242. [Zjazd chemikov /67./. 07.09.2015-11.09.2015, Horný Smokovec] R&D Projects: GA ČR(CZ) GA13-18482S Institutional research plan: CEZ:AV0Z30460519 Keywords : fossil resin * amber * resinite Subject RIV: DD - Geochemistry

  14. Spectral tuning of near-field radiative heat transfer by graphene-covered metasurfaces

    Science.gov (United States)

    Zheng, Zhiheng; Wang, Ao; Xuan, Yimin

    2018-03-01

    When two gratings are respectively covered by a layer of graphene sheet, the near-field radiative heat transfer between two parallel gratings made of silica (SiO2) could be greatly improved. As the material properties of doped silicon (n-type doping concentration is 1020 cm-3, marked as Si-20) and SiO2 differ greatly, we theoretically investigate the near-field radiative heat transfer between two parallel graphene-covered gratings made of Si-20 to explore some different phenomena, especially for modulating the spectral properties. The radiative heat flux between two parallel bulks made of Si-20 can be enhanced by using gratings instead of bulks. When the two gratings are respectively covered by a layer of graphene sheet, the radiative heat flux between two gratings made of Si-20 can be further enhanced. By tuning graphene chemical potential μ and grating filling factor f, due to the interaction between surface plasmon polaritons (SPPs) of graphene sheets and grating structures, the spectral properties of the radiative heat flux between two parallel graphene-covered gratings can be effectively regulated. This work will develop and supplement the effects of materials on the near-field radiative heat transfer for this kind of system configuration, paving a way to modulate the spectral properties of near-field radiative heat transfer.

  15. The Mojave Subsurface Bio-Geochemistry Explorer (MOSBE)

    Science.gov (United States)

    Guerrero, J.; Beegle, L.; Abbey, W.; Bhartia, R.; Kounaves, S.; Russell, M.; Towles, D.

    2012-01-01

    The MOSBE Team has developed a terrestrial field campaign to explore two subsurface biological habitats under the Mojave Desert. This field campaign will not only help us understand terrestrial desert biology, but also will develop methodologies and strategies for potential future Mars missions that would seek to explore the Martian subsurface. We have proposed to the ASTEP program to integrate a suite of field demonstrated instruments with a 20 m subsurface drill as a coherent unit, the Mojave Subsurface Bio-geochemistry Explorer. The ATK Space Modular Planetary Drill System (MPDS) requires no drilling fluid, which allows aseptic sampling, can penetrate lithic ground up to 20 meters of depth, and utilizes less than 100 Watts throughout the entire depth. The drill has been developed and demonstrated in field testing to a depth of 10 meters in Arizona, December 2002. In addition to caching a continuous core throughout the drilling depth, it also generates and caches cuttings and fines that are strata-graphically correlated with the core. As a core segment is brought to the surface, it will be analyzed for texture and structure by a color microscopic imager and for relevant chemistry and mineralogy with a UV fluorescence/Raman spectrometer. Organic and soluble ionic species will be identified through two instruments -- a microcapillary electrophoresis, and an ion trap mass spectrometer that have been developed under PIDDP, ASTID and MIDP funding.

  16. Effects of Optical Combiner and IPD Change for Convergence on Near-Field Depth Perception in an Optical See-Through HMD.

    Science.gov (United States)

    Lee, Sangyoon; Hu, Xinda; Hua, Hong

    2016-05-01

    Many error sources have been explored in regards to the depth perception problem in augmented reality environments using optical see-through head-mounted displays (OST-HMDs). Nonetheless, two error sources are commonly neglected: the ray-shift phenomenon and the change in interpupillary distance (IPD). The first source of error arises from the difference in refraction for virtual and see-through optical paths caused by an optical combiner, which is required of OST-HMDs. The second occurs from the change in the viewer's IPD due to eye convergence. In this paper, we analyze the effects of these two error sources on near-field depth perception and propose methods to compensate for these two types of errors. Furthermore, we investigate their effectiveness through an experiment comparing the conditions with and without our error compensation methods applied. In our experiment, participants estimated the egocentric depth of a virtual and a physical object located at seven different near-field distances (40∼200 cm) using a perceptual matching task. Although the experimental results showed different patterns depending on the target distance, the results demonstrated that the near-field depth perception error can be effectively reduced to a very small level (at most 1 percent error) by compensating for the two mentioned error sources.

  17. Apertureless near-field/far-field CW two-photon microscope for biological and material imaging and spectroscopic applications.

    Science.gov (United States)

    Nowak, Derek B; Lawrence, A J; Sánchez, Erik J

    2010-12-10

    We present the development of a versatile spectroscopic imaging tool to allow for imaging with single-molecule sensitivity and high spatial resolution. The microscope allows for near-field and subdiffraction-limited far-field imaging by integrating a shear-force microscope on top of a custom inverted microscope design. The instrument has the ability to image in ambient conditions with optical resolutions on the order of tens of nanometers in the near field. A single low-cost computer controls the microscope with a field programmable gate array data acquisition card. High spatial resolution imaging is achieved with an inexpensive CW multiphoton excitation source, using an apertureless probe and simplified optical pathways. The high-resolution, combined with high collection efficiency and single-molecule sensitive optical capabilities of the microscope, are demonstrated with a low-cost CW laser source as well as a mode-locked laser source.

  18. The long term behaviour of the near-field barrier surrounding a deep underground repository

    International Nuclear Information System (INIS)

    1992-02-01

    This report describes research to identify the factors which govern or influence the long-term behaviour of the near-field of a nuclear waste repository. The near-field components include the engineered barriers and the natural rock mass although the behaviour of the rock mass is of greater significance over the long-term. The factors which govern the near-field behaviour consist of the processes which operate, and the properties or parameters of the rock mass which might be modified by them. The methods which are available for the prediction of the near-field behaviour have been identified, and the emphasis on computer based methods is noted. Summary details of generic computer techniques are provided for different process modelling requirements. An attempt is made to indicate how different processes will be important at various stages during the life of the repository and how the evaluation of performance assessment process modelling requires input from empirical models and the results of other process predictions. (Author)

  19. Development of a backscattering type ultraviolet apertureless near-field scanning optical microscope.

    Science.gov (United States)

    Kwon, Sangjin; Jeong, Hyun; Jeong, Mun Seok; Jeong, Sungho

    2011-08-01

    A backscattering type ultraviolet apertureless near-field scanning optical microscope (ANSOM) for the correlated measurement of topographical and optical characteristics of photonic materials with high optical resolution was developed. The near-field Rayleigh scattering image of GaN covered with periodic submicron Cr dots showed that optical resolution around 40 nm was achievable. By measuring the tip scattered photoluminescence of InGaN/GaN multi quantum wells, the applicability of the developed microscope for high resolution fluorescence measurement was also demonstrated.

  20. Near field wireless power transfer using curved relay resonators for extended transfer distance

    International Nuclear Information System (INIS)

    Zhu, D; Beeby, S P; Clare, L; Stark, B H

    2015-01-01

    This paper investigates the performance of a near field wireless power transfer system that uses curved relay resonator to extend transfer distance. Near field wireless power transfer operates based on the near-field electromagnetic coupling of coils. Such a system can transfer energy over a relatively short distance which is of the same order of dimensions of the coupled coils. The energy transfer distance can be increased using flat relay resonators. Recent developments in printing electronics and e-textiles have seen increasing demand of embedding electronics into fabrics. Near field wireless power transfer is one of the most promising methods to power electronics on fabrics. The concept can be applied to body-worn textiles by, for example, integrating a transmitter coil into upholstery, and a flexible receiver coil into garments. Flexible textile coils take on the shape of the supporting materials such as garments, and therefore curved resonator and receiver coils are investigated in this work. Experimental results showed that using curved relay resonator can effectively extend the wireless power transfer distance. However, as the curvature of the coil increases, the performance of the wireless power transfer, especially the maximum received power, deteriorates. (paper)

  1. Teaching Mineralogy, Petrology and Geochemistry in the 21st Century: Instructional Resources for Geoscience Faculty

    Science.gov (United States)

    Mogk, D. W.; Beane, R. J.; Whitney, D. L.; Nicolaysen, K. E.; Panero, W. R.; Peck, W. H.

    2011-12-01

    Mineralogy, petrology and geochemistry (MPG) are pillars of the geoscience curriculum because of their relevance in interpreting Earth history and processes, application to geo-hazards, resources, and environmental issues, and contributions to emerging fields such as geology and human health. To keep faculty current in scientific advances in these fields, and in modern instructional methods, the On the Cutting Edge program convened a workshop at the University of Minnesota in August, 2011. This workshop builds on the previous 15 year's work that has been focused on identifying, aggregating, and developing high-quality collections of teaching activities and related resources, and in building a community of scholars in support of excellence in instruction in MPG courses. The goals of the workshop were to: a) develop an integrated, comprehensive and reviewed curriculum for MPG courses, and to seek ways to make connections with the larger geoscience curriculum; b) to explore emerging topics in MPG such as geobiology and climate change; c) demonstrate effective methods in teaching MPG in the context of Earth system science; d) share effective teaching activities and strategies for the classroom, laboratory and field including advances in pedagogy, assessments and research on learning; e) keep faculty current on recent advances in mineralogy, petrology and geochemistry research and to apply these findings to our teaching; f) explore and utilize current societal and global issues that intersect mineralogy, petrology and geochemistry to heighten the relevancy of course content for students; and h) meet colleagues and foster future teaching and research collaborations. A significant outcome of this workshop is a peer reviewed of collection of 300+ existing teaching activities, and a gap analysis to identify teaching activities needed to make these collections comprehensive and coherent. In addition, a series of thematic collections were developed to assist high priority

  2. Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

    Science.gov (United States)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2016-01-01

    A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to -50 dB was

  3. Evaluation of seismic stability of near field

    International Nuclear Information System (INIS)

    Taniguchi, Wataru; Takaji, Kazuhiko; Sugino, Hiroyuki; Mori, Koji

    1999-11-01

    For the buffer material of geological disposal of high-level radioactive waste (HLW) in Japan, it is considered to use a compacted bentonite or a compacted sand-mixture bentonite that is one kind of clay. The buffer material is expected to maintain long-term mechanical stability, to hold the waste in designated place, and to avoid the effects on the radionuclides migration. It is considered that the cyclic load due to seismic activities affects long-term mechanical stability in Japan, where many earthquakes have been occurring. In this report, aseismic mechanical stability of engineered barrier of HLW is studied by dynamic analysis based on equation of vibration, mainly in the view point of mechanical stability of the buffer. The analytical computer code that has been developed by JNC in cooperative project with National Research Institute for Earth Science and Disaster Prevention Science and Technology Agency is used in this study. Seismic wave at the disposal depth in the assumed geological environment is established by multiple reflection theory analysis, and then seismic wave at the disposal depth is used for the aseismic mechanical stability analysis. For the aseismic mechanical stability, total stress analyses (single-phase system) with the target field of near field are conducted to evaluate the shear failure of the buffer, the displacement of overpack, and vibrational behavior of the engineered barrier, and then effective stress analyses (two-phase system) with the target field of the engineered barrier are conducted to evaluate excursion in the pore water pressure within the buffer (i. e. liquefaction), concerning the non-linear dynamic properties of the buffer material. From the results, the following conclusions are obtained. (1) From the results of the total stress analyses, it is confirmed that the buffer must not reach a shear failure condition from the stresses caused by an earthquake and the overpack must not move significantly due to the inertial

  4. Near-field Localization of Audio

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2014-01-01

    Localization of audio sources using microphone arrays has been an important research problem for more than two decades. Many traditional methods for solving the problem are based on a two-stage procedure: first, information about the audio source, such as time differences-of-arrival (TDOAs......) and gain ratios-of-arrival (GROAs) between microphones is estimated, and, second, this knowledge is used to localize the audio source. These methods often have a low computational complexity, but this comes at the cost of a limited estimation accuracy. Therefore, we propose a new localization approach......, where the desired signal is modeled using TDOAs and GROAs, which are determined by the source location. This facilitates the derivation of one-stage, maximum likelihood methods under a white Gaussian noise assumption that is applicable in both near- and far-field scenarios. Simulations show...

  5. Three-dimensional propagation in near-field tomographic X-ray phase retrieval

    International Nuclear Information System (INIS)

    Ruhlandt, Aike; Salditt, Tim

    2016-01-01

    An extension of phase retrieval algorithms for near-field X-ray (propagation) imaging to three dimensions is presented, enhancing the quality of the reconstruction by exploiting previously unused three-dimensional consistency constraints. This paper presents an extension of phase retrieval algorithms for near-field X-ray (propagation) imaging to three dimensions, enhancing the quality of the reconstruction by exploiting previously unused three-dimensional consistency constraints. The approach is based on a novel three-dimensional propagator and is derived for the case of optically weak objects. It can be easily implemented in current phase retrieval architectures, is computationally efficient and reduces the need for restrictive prior assumptions, resulting in superior reconstruction quality

  6. Plane-wave spectrum approach for the calculation of electromagnetic absorption under near-field exposure conditions

    International Nuclear Information System (INIS)

    Chatterjee, I.; Gandhi, O.P.; Hagmann, M.J.; Riazi, A.

    1980-01-01

    The exposure of humans to electromagnetic near fields has not been sufficiently emphasized by researcher. We have used the plane-wave-spectrum approach to evaluate the electromagnetic field and determine the energy deposited in a lossy, homogeneous, semi-infinite slab placed in the near field of a source leaking radiation. Values of the fields and absorbed energy in the target are obtained by vector summation of the contributions of all the plane waves into which the prescribed field is decomposed. Use of a fast Fourier transform algorithm contributes to the high efficiency of the computations. The numerical results show that, for field distributions that are nearly constant over a physical extent of at least a free-space wavelength, the energy coupled into the target is approximately equal to the resulting from plane-wave exposed

  7. Double phi-Step theta-Scanning Technique for Spherical Near-Field Antenna Measurements

    DEFF Research Database (Denmark)

    Laitinen, Tommi

    2008-01-01

    Probe-corrected spherical near-field antenna measurements with an arbitrary probe set certain requirements on an applicable scanning technique. The computational complexity of the general high-order probe correction technique for an arbitrary probe, that is based on the Phi scanning, is O(N4...... a specific double Phi-step thetas scanning technique for spherical near-field antenna measurements. This technique not only constitutes an alternative spherical scanning technique, but it also enables formulating an associated probe correction technique for arbitrary probes with the computational complexity...

  8. A study of the cosmic-ray neutron field near interfaces

    CERN Document Server

    Sheu, R J; Jiang, S H

    2002-01-01

    This study investigated the characteristics of the cosmic-ray neutron field near air/ground and air/water interfaces with an emphasis on the angular distribution. Two sets of high-efficiency neutron detecting systems were used. The first one, called the Bonner Cylinders, was used for measurements of the energy information. The other one, referred to as the eight-channel neutron detector (8CND), was used to characterize the angular information of the neutron field. The measured results were used to normalize and confirm one-dimensional transport calculations for cosmic-ray neutrons below 20 MeV in the air/ground and air/water media. Annual sea level cosmic-ray neutron doses were then determined based on the obtained characteristics of low-energy cosmic-ray neutrons near interfaces and estimated contribution from high-energy neutrons.

  9. Au-bearing magnetite mineralizaion in Kashmar (alteration, mineralization, geochemistry, geochemistry and fluid inclusions;

    Directory of Open Access Journals (Sweden)

    Alireza Almasi

    2017-02-01

    Full Text Available Introduction The study area is located in the central part of the Khaf- Kashmar- Bardaskan volcano-plotunic belt (briefly KKBB. Several IOCG deposits such as Tanourjeh Au-bearing magnetite deposit and Kuh-e-Zar Specularite-rich Au deposit have been explored in KKBB. Geology, alteration, mineralization, geochemistry and fluid inclusion results in Kashmar suggest the IOCG type Au-bearing magnetite mineralization. These IOCG deposits at KKBB form at an active continental arc related to SSZ-type Sabzevar oceanic subduction. Materials and methods Use of Landsat 7+, IRS and Aster satellites. Petrography and alteration Studies in 150 thin sections of volcanic and intrusive rocks. Sampling of ore-bearing quartz vein and mineralography. Preparation of 28 geochemistry samples by the chip composite method of ore-bearing quartz vein and analyzing them in the ACME laboratory by Aqua Regia 1DX1. Fluid inclusions studies of 14 samples of quartz and barite related to the ore minerals of ore-bearing quartz vein by THM600 stage of Linkam company. Results Magmatic events in Kashmar occur at Paleocene-Eocene and include: (1 old mafic - intermediate volcano-plutonic series; (2 felsic volcanic and granitoids; and (3 parallel swarm dykes which are youngest (Almasi et al., 2016. Geochemically, Kashmar rocks are metaluminous to highly peraluminous and Tholeitic to calc-alkaline and shoshonitic in composition (Almasi et al., 2016. The field characteristics, together with isotope and geochemical analyses show that all rock types are essentially co-magmatic and post-collisional I-type (Almasi et al., 2016. Alteration of Kashmar is described in two ways: (1 intense ellipsoidal-linear Argillic-Sillicification and low sericitic with Silica caps and with medium widespread and propylitic alterations in triple regions, next to Dorouneh fault; and (2 Medium Hematite-Carbonate-Chlorite-Silicification alterations in Kamarmard heights. In parts of near the Doruneh fault, sometimes

  10. Particle and field signatures of substorms in the near magnetotail

    International Nuclear Information System (INIS)

    Baker, D.N.

    1983-01-01

    The near-earth magnetotail (10 less than or equal to r less than or equal to 20 R/sub E/) portion of the terrestrial magnetosphere is very likely the region in which magnetospheric substorms are initiated and it is in this location that substorm-related magnetic reconnection appears to occur. An observational advantage compared to other astrophysical regions is that the near magnetotail can be nearly continuously monitored by spacecraft that are relatively fixed in location. Observations of magnetic fields and plasma distribution functions in the neartail reveal a very regular and predictable sequence of variation in association with substorms. These data, considered in a global context, provide very strong evidence for the neutral line substorm model and, thus, for the regular occurrence of magnetic reconnection in the near-earth magnetotail during substorms

  11. The Thermodynamics of Selenium Minerals in Near-Surface Environments

    Directory of Open Access Journals (Sweden)

    Vladimir Krivovichev

    2017-10-01

    Full Text Available Selenium compounds are relatively rare as minerals; there are presently only 118 known mineral species. This work is intended to codify and systematize the data of mineral systems and the thermodynamics of selenium minerals, which are unstable (selenides or formed in near-surface environments (selenites, where the behavior of selenium is controlled by variations of the redox potential and the acidity of solutions at low temperatures and pressures. These parameters determine the migration of selenium and its precipitation as various solid phases. All selenium minerals are divided into four groups—native selenium, oxide, selenides, and oxysalts—anhydrous selenites (I and hydrous selenites and selenates (II. Within each of the groups, minerals are codified according to the minimum number of independent elements necessary to define the composition of the mineral system. Eh–pH diagrams were calculated and plotted using the Geochemist’s Workbench (GMB 9.0 software package. The Eh–pH diagrams of the Me–Se–H2O systems (where Me = Co, Ni, Fe, Cu, Pb, Zn, Cd, Hg, Ag, Bi, As, Sb, Al and Ca were plotted for the average contents of these elements in acidic waters in the oxidation zones of sulfide deposits. The possibility of the formation of Zn, Cd, Ag and Hg selenites under natural oxidation conditions in near surface environments is discussed.

  12. Induced Light Emission from Quantum Dots: The Directional Near-Field Pattern

    DEFF Research Database (Denmark)

    Iezhokin, Igor; Keller, Ole; Lozovski, Valeri

    2010-01-01

    The optical Lippmann-Schwinger equation, supplemented by the microscopic conductivity tensor, is used to establish a near-field radiation theory for a mesoscopic particle. The present theory deviates from previous ones in that it allows one to take into account the finite size of the particle...... in a selfconsistent local-field calculation. The main result of the basic theory is illustrated by a number of numerical calculations on box-shaped quantum dots keeping only two optically mobile electrons. Particular attendance is paid to the distance and angular dependences of the near-field radiation pattern When...... the distance between the particle and observation point exceeds just a few times the linear dimension of the particle the directional radiation diagrams all become qualitatively identical to those of an electric point-dipole radiator The result of the present theory may be of particular interest for studies...

  13. Beam alignment based on two-dimensional power spectral density of a near-field image.

    Science.gov (United States)

    Wang, Shenzhen; Yuan, Qiang; Zeng, Fa; Zhang, Xin; Zhao, Junpu; Li, Kehong; Zhang, Xiaolu; Xue, Qiao; Yang, Ying; Dai, Wanjun; Zhou, Wei; Wang, Yuanchen; Zheng, Kuixing; Su, Jingqin; Hu, Dongxia; Zhu, Qihua

    2017-10-30

    Beam alignment is crucial to high-power laser facilities and is used to adjust the laser beams quickly and accurately to meet stringent requirements of pointing and centering. In this paper, a novel alignment method is presented, which employs data processing of the two-dimensional power spectral density (2D-PSD) for a near-field image and resolves the beam pointing error relative to the spatial filter pinhole directly. Combining this with a near-field fiducial mark, the operation of beam alignment is achieved. It is experimentally demonstrated that this scheme realizes a far-field alignment precision of approximately 3% of the pinhole size. This scheme adopts only one near-field camera to construct the alignment system, which provides a simple, efficient, and low-cost way to align lasers.

  14. Very high-accuracy calibration of radiation pattern and gain of a near-field probe

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Nielsen, Jeppe Majlund; Breinbjerg, Olav

    2014-01-01

    In this paper, very high-accuracy calibration of the radiation pattern and gain of a near-field probe is described. An open-ended waveguide near-field probe has been used in a recent measurement of the C-band Synthetic Aperture Radar (SAR) Antenna Subsystem for the Sentinel 1 mission of the Europ...

  15. Handbook of environmental isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Baskaran, Mark (ed.) [Wayne State Univ., Detroit, MI (United States). Dept. Geology

    2011-07-01

    Applications of radioactive and stable isotopes have revolutionized our understanding of the Earth and near-earth surface processes. The utility of the isotopes are ever-increasing and our sole focus is to bring out the applications of these isotopes as tracers and chronometers to a wider audience so that they can be used as powerful tools to solve environmental problems. New developments in this field remain mostly in peer-reviewed journal articles and hence our goal is to synthesize these findings for easy reference for students, faculty, regulators in governmental and non-governmental agencies, and environmental companies. While this volume maintains its rigor in terms of its depth of knowledge and quantitative information, it contains the breadth needed for wide variety problems and applications in the environmental sciences. This volume presents all of the newer and older applications of isotopes pertaining to the environmental problems in one place that is readily accessible to readers. This book not only has the depth and rigor that is needed for academia, but it has the breadth and case studies to illustrate the utility of the isotopes in a wide variety of environments (atmosphere, oceans, lakes, rivers and streams, terrestrial environments, and sub-surface environments) and serves a large audience, from students and researchers, regulators in federal, state and local governments, and environmental companies. (orig.)

  16. Sulfur Geochemistry of a Lacustrine Record from Taiwan Reveals Enhanced Marine Aerosol Input during the Early Holocene.

    Science.gov (United States)

    Ding, Xiaodong; Li, Dawei; Zheng, Liwei; Bao, Hongyan; Chen, Huei-Fen; Kao, Shuh-Ji

    2016-12-12

    Lacustrine record of marine aerosol input has rarely been documented. Here, we present the sulfur geochemistry during the last deglaciation and early Holocene of a sediment core retrieved from the Dongyuan Lake in southern Taiwan. An unusually high sulfur peak accompanying pyrite presence is observed at 10.5 ka BP. Such high sulfur content in lacustrine record is unusual. The δ 34 S of sulfur varied from +9.5 to + 17.1‰ with two significant positive shifts at 10.5 and 9.4 ka BP. The sources of sulfur and potential processes involving the sulfur isotope variation including bacterial sulfate reduction, volcanic emissions, in-catchment sulfide oxidation and marine aerosol input are discussed. Enhanced marine aerosol input is the most likely explanation for such sulfur peaks and δ 34 S shifts. The positive δ 34 S shifts appeared concurrently with the maximum landslide events over Taiwan resulted from enhanced typhoon activities. The synchronicity among records suggests that increased typhoon activities promoted sea spray, and consequently enhanced the marine aerosol input with 34 S-enriched sulfate. Our sulfur geochemistry data revealed sea spray history and marine influence onto terrestrial environment at coastal regions. Wider coverage of spatial-temporal lacustrine sulfur geochemistry record is needed to validate the applicability of sulfur proxy in paleoenvironmental research.

  17. Optical security based on near-field processes at the nanoscale

    International Nuclear Information System (INIS)

    Naruse, Makoto; Tate, Naoya; Ohtsu, Motoichi

    2012-01-01

    Optics has been playing crucial roles in security applications ranging from authentication and watermarks to anti-counterfeiting. However, since the fundamental physical principle involves optical far-fields, or propagating light, diffraction of light causes severe difficulties, for example in device scaling and system integration. Moreover, conventional security technologies in use today have been facing increasingly stringent demands to safeguard against threats such as counterfeiting of holograms, requiring innovative physical principles and technologies to overcome their limitations. Nanophotonics, which utilizes interactions between light and matter at the nanometer scale via optical near-field interactions, can break through the diffraction limit of conventional propagating light. Moreover, nanophotonics has some unique physical attributes, such as localized optical energy transfer and the hierarchical nature of optical near-field interactions, which pave the way for novel security functionalities. This paper reviews the physical principles and describes some experimental demonstrations of systems based on nanophotonics with respect to security applications such as tamper resistance against non-invasive and invasive attacks, hierarchical information retrieval, hierarchical holograms, authentication, and traceability. (paper)

  18. Prediction and near-field observation of skull-guided acoustic waves.

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2017-06-21

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. We observed a skull-guided wave propagation over a lateral distance of at least 3 mm, with a half-decay length in the direction perpendicular to the skull ranging from 35 to 300 μm at 6 and 0.5 MHz, respectively. Propagation losses are mostly attributed to the heterogenous acoustic properties of the skull. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  19. High-Throughput Near-Field Optical Nanoprocessing of Solution-Deposited Nanoparticles

    KAUST Repository

    Pan, Heng

    2010-07-27

    The application of nanoscale electrical and biological devices will benefit from the development of nanomanufacturing technologies that are highthroughput, low-cost, and flexible. Utilizing nanomaterials as building blocks and organizing them in a rational way constitutes an attractive approach towards this goal and has been pursued for the past few years. The optical near-field nanoprocessing of nanoparticles for high-throughput nanomanufacturing is reported. The method utilizes fluidically assembled microspheres as a near-field optical confinement structure array for laserassisted nanosintering and nanoablation of nanoparticles. By taking advantage of the low processing temperature and reduced thermal diffusion in the nanoparticle film, a minimum feature size down to ≈i100nm is realized. In addition, smaller features (50nm) are obtained by furnace annealing of laser-sintered nanodots at 400 °C. The electrical conductivity of sintered nanolines is also studied. Using nanoline electrodes separated by a submicrometer gap, organic field-effect transistors are subsequently fabricated with oxygen-stable semiconducting polymer. © 2010 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim.

  20. Prediction and near-field observation of skull-guided acoustic waves

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2017-06-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. We observed a skull-guided wave propagation over a lateral distance of at least 3 mm, with a half-decay length in the direction perpendicular to the skull ranging from 35 to 300 μm at 6 and 0.5 MHz, respectively. Propagation losses are mostly attributed to the heterogenous acoustic properties of the skull. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  1. Near-field characteristics of radiating-wave simulator antenna based on TEM horn

    International Nuclear Information System (INIS)

    Tian Chunming; Ge Debiao

    2004-01-01

    This paper presents a novel antenna of NEMP (nuclear electromagnetic pulse) radiating-wave simulator, which is analyzed and optimized using the finite-difference time domain (FDTD) method. The intense voltage pulse is fed as the source to this antenna by the coaxial line. The parallel plate transmission line and the size of the transverse electromagnetic horn are optimized. The near field of antenna is analyzed, and the effects of the size on the near field are also given. The antenna designed in this paper can well satisfy the requirement for studying the EMP effects

  2. Salton Sea geothermal field as a natural analog for the near-field in a salt high-level nuclear waste repository

    International Nuclear Information System (INIS)

    Elders, W.A.; Moody, J.B.; Battelle Memorial Inst., Columbus, OH)

    1984-01-01

    The Salton Sea Geothermal Field (SSGF), on the delta of the Colorado River in southern California, is being studied as a natural analog for the near-field environment of proposed nuclear waste repositories in salt. A combination of mineralogical and geochemical methods is being employed to develop a three-dimenisonal picture of temperature, salinity, lithology, mineralogy, and chemistry of reactions between the reservoir rocks and the hot brines. Our aim is to obtain quantitative data on mineral stabilities and on mobilities of the naturally occurring radionuclides of concern in Commercial High-Level Waste (CHLW). These data will be used to validate the EQ3/6 geochemical code under development to model the salt near-field repository behavior. Maximum temperatures encountered in wells in the SSGF equal or exceed peak temperatures expected in a salt repository. Brines produced from these wells have major element chemistry similar to brines from candidate salt sites. Relative to the rocks, these brines are enriched in Na, Mn, Sr, Ra, and Po, depleted in Ba, Si, Mg, Ti, and Al, and strongly depleted in U and Th. However, the unaltered rocks contain only about 2 to 3 ppm of U and 4 to 12 ppm of Th, largely in detrital epidotes and zircons. Samples of hydrothermally altered rocks from a wide range of temperature and salinity show rather similar uniform low concentrations of these elements, even when authigenic illite, chlorite, ipidote and feldspar are present. These observations suggest that U and Th are relatively immobile in these hot brines. However, Ra, Po, Cs, and Sr are relatively mobile. Work is continuing to document naturally occurring radionuclide partitioning between SSGF minears and brine over a range of temperature, salinity, and lithology. 8 refs., 7 figs., 2 tabs

  3. A comparison of SONAH and IBEM for near-field acoustic holography

    DEFF Research Database (Denmark)

    Juhl, Peter Møller

    2008-01-01

    Among the popular techniques for acoustic source identification in complex environments are the Statistically Optimal Near Acoustic Holography (SONAH) and the Inverse Boundary Element Method (IBEM). These two methods are quite different regarding the underlying assumptions and the practical...

  4. Near-field enhanced electron acceleration from dielectric nanospheres in intense few-cycle laser fields

    International Nuclear Information System (INIS)

    Zherebtsov, S.; Znakovskaya, I.; Wirth, A.; Herrwerth, O.; Suessmann, F.; Ahmad, I.; Trushin, S.; Fennel, Th.; Plenge, J.; Antonsson, E.

    2010-01-01

    Complete text of publication follows. The interaction of nanostructured materials with few-cycle laser light has attracted significant attention lately. This interest is driven by both the quest for fundamental insight into the real-time dynamics of many-electron systems and a wide range of far-reaching applications, such as, e.g. ultrafast computation and information storage on the nanoscale and the generation of XUV frequency combs. We investigated the above-threshold electron emission from isolated SiO 2 nanoparticles in waveform controlled few-cycle laser fields at intensities close to the tunneling regime. The enhancement of the electron acceleration from the silica nanoparticles was explored as a function of the particle size (ranging from 50 to 147 nm) and the laser peak intensity (1 - 4x10 13 W/cm 2 ). Obtained cut-off values in the kinetic energy spectra are displayed in Fig. 1. The cut-off values show a linear dependence with intensity within the studied intensity range, with the average cut-off energy being 53 U P , indicated by the black line. Quasi-classical simulations of the emission process reveal that electron rescattering in the locally enhanced near-field of the particle is responsible for the large energy gain. The observed near-field enhancement offers promising new routes for pushing the limits of strong-field phenomena relying on electron rescattering, such as, high-harmonic generation and molecular imaging.

  5. The near-field acoustic levitation for spheres by transducer with concave spherical radiating surface

    International Nuclear Information System (INIS)

    Liu, Jian Fang; Sun, Xu Guang; Jiao, Xiao Yang; Chen, Hong Xia; Hua, Shun Ming; Zhang, Hong Chun

    2013-01-01

    To levitate ICF target spheres in the near-field acoustic levitation, a transducer with concave spherical radiating surface and a nearfield acoustic levitation system is established. The concave spherical radiating surface of the transducer is designed by the finite element parametric method. Then the levitation height and levitation perturbation of spheres with different mass and diameters in the near-field acoustic levitation system are tested and discussed in the driving voltage at 400V, 500V and 600V, respectively, when the levitation system is under the resonant frequency. Finally, based on the experimental results, the height formula of the near-field acoustic levitation for spheres is deduced by introducing a coupling coefficient.

  6. The near-field acoustic levitation for spheres by transducer with concave spherical radiating surface

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jian Fang; Sun, Xu Guang; Jiao, Xiao Yang; Chen, Hong Xia [Jilin University, Changchun (China); Hua, Shun Ming [Zhejiang University, Ningbo (China); Zhang, Hong Chun [Aviation University of AirForce, Changchun (China)

    2013-02-15

    To levitate ICF target spheres in the near-field acoustic levitation, a transducer with concave spherical radiating surface and a nearfield acoustic levitation system is established. The concave spherical radiating surface of the transducer is designed by the finite element parametric method. Then the levitation height and levitation perturbation of spheres with different mass and diameters in the near-field acoustic levitation system are tested and discussed in the driving voltage at 400V, 500V and 600V, respectively, when the levitation system is under the resonant frequency. Finally, based on the experimental results, the height formula of the near-field acoustic levitation for spheres is deduced by introducing a coupling coefficient.

  7. Assessment of power-plant effects on zooplankton in the near field

    International Nuclear Information System (INIS)

    Polgar, T.T.; Bongers, L.H.; Krainak, G.M.

    1976-01-01

    With the use of a simple entrainment model that takes into account tidal recirculation, mixing, and once-through kill rate, theoretical expressions are derived for ratios of densities of live organisms at the intake of a power plant to densities in the far field. Experimental data on the abundances of dead and live stages of Eurytemora affinis and Acartia tonsa are used to compare to model results. A study of the entrainment of zooplankton near the intake of the Morgantown power plant and a concurrent study of the distribution of zooplankton in the Potomac River provided the biological data. Physical information was derived from extensive hydrographic measurements. Comparing experimental data with model predictions showed that radical depletions occurred in the naupliar stages near the plant site which cannot be accounted for by cooling-system or delayed entrainment mortalities. These near-field changes are attributed to avoidance reactions and to mortalities in the vicinity of the plant

  8. Modeling and Measurement of Electromagnetic Fields Near LORAN-C and OMEGA Stations

    Science.gov (United States)

    1987-06-15

    high-speed computers. This approach to field strength determination has several advantages and is often used along with measurements in a...Further from the feed, advantage was taken of the symmetry of the antenna systems. Field strengths near monopole antennas are cylindrically symmetric...was extended a short distnnce beyond the shield to create an electric field probe. Magnetic fields were measured using the Alltech loop, which

  9. Large-area parallel near-field optical nanopatterning of functional materials using microsphere mask

    Energy Technology Data Exchange (ETDEWEB)

    Chen, G.X. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Hong, M.H. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)], E-mail: Hong_Minghui@dsi.a-star.edu.sg; Lin, Y. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Wang, Z.B. [Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Ng, D.K.T. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Xie, Q. [Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Tan, L.S. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Chong, T.C. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)

    2008-01-31

    Large-area parallel near-field optical nanopatterning on functional material surfaces was investigated with KrF excimer laser irradiation. A monolayer of silicon dioxide microspheres was self-assembled on the sample surfaces as the processing mask. Nanoholes and nanospots were obtained on silicon surfaces and thin silver films, respectively. The nanopatterning results were affected by the refractive indices of the surrounding media. Near-field optical enhancement beneath the microspheres is the physical origin of nanostructure formation. Theoretical calculation was performed to study the intensity of optical field distributions under the microspheres according to the light scattering model of a sphere on the substrate.

  10. Environment, Environmental Restoration, and Waste Management Field Organization Directory

    International Nuclear Information System (INIS)

    1993-07-01

    This directory was developed by the Office of Environmental Guidance, RCRA/CERCLA Division (EH-231) from an outgrowth of the Departments efforts to identify and establish the regulatory response lead persons in the Field Organizations. The directory was developed for intemal EH-231 use to identify both the DOE and DOE contractor Field Organizations in the Environment, Environmental Restoration and Waste Management areas. The Field Organization directory is divided into three substantive sections: (1) Environment; (2) Environmental Restoration; and (3) Waste Management which are organized to correspond to the management hierarchy at each Field Organization. The information provided includes the facility name and address, individual managers name, and telephone/fax numbers

  11. Precise quantization of anomalous Hall effect near zero magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Bestwick, A. J. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fox, E. J. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Kou, Xufeng [Univ. of California, Los Angeles, CA (United States); Pan, Lei [Univ. of California, Los Angeles, CA (United States); Wang, Kang L. [Univ. of California, Los Angeles, CA (United States); Goldhaber-Gordon, D. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-05-04

    In this study, we report a nearly ideal quantum anomalous Hall effect in a three-dimensional topological insulator thin film with ferromagnetic doping. Near zero applied magnetic field we measure exact quantization in the Hall resistance to within a part per 10,000 and a longitudinal resistivity under 1 Ω per square, with chiral edge transport explicitly confirmed by nonlocal measurements. Deviations from this behavior are found to be caused by thermally activated carriers, as indicated by an Arrhenius law temperature dependence. Using the deviations as a thermometer, we demonstrate an unexpected magnetocaloric effect and use it to reach near-perfect quantization by cooling the sample below the dilution refrigerator base temperature in a process approximating adiabatic demagnetization refrigeration.

  12. Resolved magnetic-field structure and variability near the event horizon of Sagittarius A.

    Science.gov (United States)

    Johnson, Michael D; Fish, Vincent L; Doeleman, Sheperd S; Marrone, Daniel P; Plambeck, Richard L; Wardle, John F C; Akiyama, Kazunori; Asada, Keiichi; Beaudoin, Christopher; Blackburn, Lindy; Blundell, Ray; Bower, Geoffrey C; Brinkerink, Christiaan; Broderick, Avery E; Cappallo, Roger; Chael, Andrew A; Crew, Geoffrey B; Dexter, Jason; Dexter, Matt; Freund, Robert; Friberg, Per; Gold, Roman; Gurwell, Mark A; Ho, Paul T P; Honma, Mareki; Inoue, Makoto; Kosowsky, Michael; Krichbaum, Thomas P; Lamb, James; Loeb, Abraham; Lu, Ru-Sen; MacMahon, David; McKinney, Jonathan C; Moran, James M; Narayan, Ramesh; Primiani, Rurik A; Psaltis, Dimitrios; Rogers, Alan E E; Rosenfeld, Katherine; SooHoo, Jason; Tilanus, Remo P J; Titus, Michael; Vertatschitsch, Laura; Weintroub, Jonathan; Wright, Melvyn; Young, Ken H; Zensus, J Anton; Ziurys, Lucy M

    2015-12-04

    Near a black hole, differential rotation of a magnetized accretion disk is thought to produce an instability that amplifies weak magnetic fields, driving accretion and outflow. These magnetic fields would naturally give rise to the observed synchrotron emission in galaxy cores and to the formation of relativistic jets, but no observations to date have been able to resolve the expected horizon-scale magnetic-field structure. We report interferometric observations at 1.3-millimeter wavelength that spatially resolve the linearly polarized emission from the Galactic Center supermassive black hole, Sagittarius A*. We have found evidence for partially ordered magnetic fields near the event horizon, on scales of ~6 Schwarzschild radii, and we have detected and localized the intrahour variability associated with these fields. Copyright © 2015, American Association for the Advancement of Science.

  13. Estimate on the uncertainty of predicting radiated emission from near-field scan caused by insufficient or inaccurate near-field data

    DEFF Research Database (Denmark)

    Sørensen, Morten; Radchenko, Andriy; Kam, Keong

    2012-01-01

    Near-field scan on a Huygens’ box can be used in order to predict the maximal radiated emission from a Printed Circuit Board. The significance of step size and phase accuracy, and the importance of a full Huygens’ box are investigated by simulation of two different models with two different...... numerical methods. The prediction of maximal radiated emission is quite robust but the results also show that a full scan on all six surfaces is probably needed....

  14. Laminar and turbulent nozzle-jet flows and their acoustic near-field

    International Nuclear Information System (INIS)

    Bühler, Stefan; Obrist, Dominik; Kleiser, Leonhard

    2014-01-01

    We investigate numerically the effects of nozzle-exit flow conditions on the jet-flow development and the near-field sound at a diameter-based Reynolds number of Re D = 18 100 and Mach number Ma = 0.9. Our computational setup features the inclusion of a cylindrical nozzle which allows to establish a physical nozzle-exit flow and therefore well-defined initial jet-flow conditions. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. The goal is to document and to compare the effects of the different jet inflows on the jet flow development and the sound radiation. For laminar and transitional boundary layers, transition to turbulence in the jet shear layer is governed by the development of Kelvin-Helmholtz instabilities. With the turbulent nozzle boundary layer, the jet flow development is characterized by a rapid changeover to a turbulent free shear layer within about one nozzle diameter. Sound pressure levels are strongly enhanced for laminar and transitional exit conditions compared to the turbulent case. However, a frequency and frequency-wavenumber analysis of the near-field pressure indicates that the dominant sound radiation characteristics remain largely unaffected. By applying a recently developed scaling procedure, we obtain a close match of the scaled near-field sound spectra for all nozzle-exit turbulence levels and also a reasonable agreement with experimental far-field data

  15. Astrobiology Field Research in Moon/Mars Analogue Environments: Preface

    Science.gov (United States)

    Foing, B. H.; Stoker, C.; Ehrenfreund, P.

    2011-01-01

    Extreme environments on Earth often provide similar terrain conditions to landing/operation sites on Moon and Mars. Several field campaigns (EuroGeoMars2009 and DOMMEX/ILEWG EuroMoonMars from November 2009 to March 2010) were conducted at the Mars Desert Research Station (MDRS) in Utah. Some of the key astrobiology results are presented in this special issue on Astrobiology field research in Moon/Mars analogue environments relevant to investigate the link between geology, minerals, organics and biota. Preliminary results from a multidisciplinary field campaign at Rio Tinto in Spain are presented.

  16. Thermodynamic coupling of heat and matter flows in near-field regions of nuclear waste repositories

    International Nuclear Information System (INIS)

    Carnahan, C.L.

    1983-11-01

    In near-field regions of nuclear waste repositories, thermodynamically coupled flows of heat and matter can occur in addition to the independent flows in the presence of gradients of temperature, hydraulic potential, and composition. The following coupled effects can occur: thermal osmosis, thermal diffusion, chemical osmosis, thermal filtration, diffusion thermal effect, ultrafiltration, and coupled diffusion. Flows of heat and matter associated with these effects can modify the flows predictable from the direct effects, which are expressed by Fourier's law, Darcy's law, and Fick's law. The coupled effects can be treated quantitatively together with the direct effects by the methods of the thermodynamics of irreversible processes. The extent of departure of fully coupled flows from predictions based only on consideration of direct effects depends on the strengths of the gradients driving flows, and may be significant at early times in backfills and in near-field geologic environments of repositories. Approximate calculations using data from the literature and reasonable assumptions of repository conditions indicate that thermal-osmotic and chemical-osmotic flows of water in semipermeable backfills may exceed Darcian flows by two to three orders of magnitude, while flows of solutes may be reduced greatly by ultrafiltration and chemical osmosis, relative to the flows predicted by advection and diffusion alone. In permeable materials, thermal diffusion may contribute to solute flows to a smaller, but still significant, extent

  17. Self-supervised Traversability Assessment in Field Environments with Lidar and Camera

    DEFF Research Database (Denmark)

    Hansen, Mikkel Kragh; Underwood, James; Karstoft, Henrik

    , the visual classifier detects non-traversable image patches as outliers from a Gaussian Mixture Model that maintains the appearance of only traversable ground. Results Our method is evaluated using a diverse dataset of agricultural fields and orchards gathered with a perception research robot developed......Introduction The application of robotic automation within agriculture is increasing. There is a high demand for fully autonomous robots that are both efficient, reliable and affordable. In order to ensure safety, autonomous agricultural vehicles must perceive the environment and detect potential...... obstacles and threats across a variety of environmental conditions. In this paper, a self-supervised framework is proposed, combining laser range sensing from a lidar with images from a monocular camera to reliably assess terrain traversability/navigability. Methods The method uses a near-to-far approach...

  18. Early results from Magsat. [studies of near-earth magnetic fields

    Science.gov (United States)

    Langel, R. A.; Estes, R. H.; Mayhew, M. A.

    1981-01-01

    Papers presented at the May 27, 1981 meeting of the American Geophysical Union concerning early results from the Magsat satellite program, which was designed to study the near-earth magnetic fields originating in the core and lithosphere, are discussed. The satellite was launched on October 30, 1979 into a sun-synchronous (twilight) orbit, and re-entered the atmosphere on June 11, 1980. Instruments carried included a cesium vapor magnetometer to measure field magnitudes, a fluxgate magnetometer to measure field components and an optical system to measure fluxgate magnetometer orientation. Early results concerned spherical harmonic models, fields due to ionospheric and magnetospheric currents, the identification and interpretation of fields from lithospheric sources. The preliminary results confirm the possibility of separating the measured field into core, crustal and external components, and represent significant developments in analytical techniques in main-field modelling and the physics of the field sources.

  19. Near-Field Ground Motion Modal versus Wave Propagation Analysis

    Directory of Open Access Journals (Sweden)

    Artur Cichowicz

    2010-01-01

    Full Text Available The response spectrum generally provides a good estimate of the global displacement and acceleration demand of far-field ground motion on a structure. However, it does not provide accurate information on the local shape or internal deformation of the response of the structure. Near-field pulse-like ground motion will propagate through the structure as waves, causing large, localized deformation. Therefore, the response spectrum alone is not a sufficient representation of near-field ground motion features. Results show that the drift-response technique based on a continuous shear-beam model has to be employed here to estimate structure-demand parameters when structure is exposed to the pulse like ground motion. Conduced modeling shows limited applicability of the drift spectrum based on the SDOF approximation. The SDOF drift spectrum approximation can only be applied to structures with smaller natural periods than the dominant period of the ground motion. For periods larger than the dominant period of ground motion the SDOF drift spectra model significantly underestimates maximum deformation. Strong pulse-type motions are observed in the near-source region of large earthquakes; however, there is a lack of waveforms collected from small earthquakes at very close distances that were recorded underground in mines. The results presented in this paper are relevant for structures with a height of a few meters, placed in an underground excavation. The strong ground motion sensors recorded mine-induced earthquakes in a deep gold mine, South Africa. The strongest monitored horizontal ground motion was caused by an event of magnitude 2 at a distance of 90 m with PGA 123 m/s2, causing drifts of 0.25%–0.35%. The weak underground motion has spectral characteristics similar to the strong ground motion observed on the earth's surface; the drift spectrum has a maximum value less than 0.02%.

  20. A line array based near field imaging technique for characterising acoustical properties of elongated targets

    NARCIS (Netherlands)

    Driessen, F.P.G.

    1995-01-01

    With near field imaging techniques the acoustical pressure waves at distances other than the recorded can be calculated. Normally, acquisition on a two dimensional plane is necessary and extrapolation is performed by a Rayleigh integral. A near field single line instead of two dimensional plane

  1. Literature survey of redox reactions in the near field

    International Nuclear Information System (INIS)

    Miki, Takahito; Chiba, Tamotsu; Inagaki, Manabu; Sasamoto, Hiroshi; Yui, Mikazu

    2000-01-01

    This report presents a summary of literature survey about geochemical reactions which are important to evaluate the redox conditions in the near field rock mass and buffer. The results of literature survey are summarized as follows; Minerals including ferrous iron and organic materials in the rock mass are important reductants. Initial stage after closure of repository, oxygen will be consumed by pyrite, because the reaction rate between pyrite and oxygen is relatively fast. It is possible to estimate the redox capacity for reductants by rock (mineral)-water interaction experiment in a laboratory. And it is expected that the ferrous iron-rich rock and higher porosity rock may have bigger redox capacity. It is impossible to estimate the oxygen consumption rate by reductants such as minerals including ferrous iron. The rate law and rate constant for the oxidation reaction of ferrous iron in the solution are also determined. As a conclusion, it seems that we can evaluate kinetically the evolution of geochemical conditions in the near field rock mass and buffer by excavation of drifts, based on data derived from these existing literatures. (author)

  2. Effects of thruster firings on the shuttle's plasma and electric field environment

    International Nuclear Information System (INIS)

    Machuzak, J.S.; Burke, W.J.; Retterer, J.M.; Hunton, D.E.; Jasperse, J.R.; Smiddy, M.

    1993-01-01

    Simultaneous plasma and AC/DC electric field measurements taken during the space shuttle mission STS-4 at times of prolonged thruster firings are analyzed and cross correlated. Depending on the orientation of the shuttle's velocity vector to the magnetic field, ion densities and electric field wave spectra were enhanced or decreased. The systematic picture of interactions within the shuttle's plasma/neutral gas environment of Cairns and Gurnett (1991b) is confirmed and extended. Waves are excited by outgassed and thruster-ejected molecules that ionize in close proximity to the shuttle. On time scales significantly less than an ion gyroperiod, the newly created ions act as beams in the background plasma. These beams are sources of VLF waves that propagate near the shuttle and intensify during thruster firings. Plasma density depletions and/or the shuttle's geometry may hinder wave detection in the payload bay. A modified two-stream analysis indicates that beam components propagating at large angles to the magnetic field are unstable to the growth of lower hybrid waves. The beam-excited, lower hybrid waves heat some electrons to sufficient energies to produce impact ionization. Empirical evidence for other wave-growth mechanisms outside the lower-hybrid band is presented. 42 refs., 15 figs., 3 tabs

  3. Application of the planar-scanning technique to the near-field dosimetry of millimeter-wave radiators.

    Science.gov (United States)

    Zhao, Jianxun; Lu, Hongmin; Deng, Jun

    2015-02-01

    The planar-scanning technique was applied to the experimental measurement of the electric field and power flux density (PFD) in the exposure area close to the millimeter-wave (MMW) radiator. In the near-field region, the field and PFD were calculated from the plane-wave spectrum of the field sampled on a scan plane far from the radiator. The measurement resolution was improved by reducing the spatial interval between the field samples to a fraction of half the wavelength and implementing multiple iterations of the fast Fourier transform. With the reference to the results from the numerical calculation, an experimental evaluation of the planar-scanning measurement was made for a 50 GHz radiator. Placing the probe 1 to 3 wavelengths from the aperture of the radiator, the direct measurement gave the near-field data with significant differences from the numerical results. The planar-scanning measurement placed the probe 9 wavelengths away from the aperture and effectively reduced the maximum and averaged differences in the near-field data by 70.6% and 65.5%, respectively. Applied to the dosimetry of an open-ended waveguide and a choke ring antenna for 60 GHz exposure, the technique proved useful to the measurement of the PFD in the near-field exposure area of MMW radiators. © 2015 Wiley Periodicals, Inc.

  4. High-Fidelity Trapped-Ion Quantum Logic Using Near-Field Microwaves.

    Science.gov (United States)

    Harty, T P; Sepiol, M A; Allcock, D T C; Ballance, C J; Tarlton, J E; Lucas, D M

    2016-09-30

    We demonstrate a two-qubit logic gate driven by near-field microwaves in a room-temperature microfabricated surface ion trap. We introduce a dynamically decoupled gate method, which stabilizes the qubits against fluctuating energy shifts and avoids the need to null the microwave field. We use the gate to produce a Bell state with fidelity 99.7(1)%, after accounting for state preparation and measurement errors. The gate is applied directly to ^{43}Ca^{+} hyperfine "atomic clock" qubits (coherence time T_{2}^{*}≈50  s) using the oscillating magnetic field gradient produced by an integrated microwave electrode.

  5. Magnetic field structure near the plasma boundary in helical systems and divertor tokamaks

    International Nuclear Information System (INIS)

    Nagasaki, Kazunobu; Itoh, Kimitaka

    1990-02-01

    Magnetic field structure of the scrape off layer (SOL) region in both helical systems and divertor tokamaks is studied numerically by using model fields. The connection length of the field line to the wall is calculated. In helical systems, the connection length, L, has a logarithmic dependence on the distance from the outermost magnetic surface or that from the residual magnetic islands. The effect of axisymmetric fields on the field structure is also determined. In divertor tokamaks, the connection length also has logarithmic properties near the separatrix. Even when the perturbations, which resonate to rational surfaces near the plasma boundary, are added, logarithmic properties still remain. We compare the connection length of torsatron/helical-heliotron systems with that of divertor tokamaks. It is found that the former is shorter than the latter by one order magnitude with similar aspect ratio. (author)

  6. A total generalized variation approach for near-field acoustic holography

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    2017-01-01

    Near-field methods based on microphone array measurements are useful to understand how a source radiates sound. Due to discretization errors, these methods are typically restricted to low frequencies. Sparse approaches have gained considerable attention, as they can potentially recover a seemingl...

  7. Geochemistry of sulphur in petroleum systems

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Orr, W.L.

    1990-01-01

    A renaissance in the 1980s concerning geochemistry of sulfur in fossil fuels makes an update of the subject timely. Papers developed from the 1989 ACS Symposium in Dallas provide a cross-section of recent research and progress in our understanding of the abundance and nature of organically bound

  8. Groundwater flow modeling for near-field of a hypothetical near-surface disposal facility

    International Nuclear Information System (INIS)

    Park, H. Y.; Park, J. W.; Jang, G. M.; Kim, C. R.

    2000-01-01

    For a hypothetical near-surface radioactive disposal facility, the behavior of groundwater flow around the near-field of disposal vault located at the unsaturated zone were analyzed. Three alternative conceptual models proposed as the hydraulic barrier layer design were simulated to assess the hydrologic performance of engineered barriers for the facility. In order to evaluate the seepage possibility of the infiltrated water passed through the final disposal cover after the facility closure, the flow path around and water flux through each disposal vault were compared. The hydrologic parameters variation that accounts for the long-term aging and degradation of the cover and engineered materials was considered in the simulations. The results showed that it is necessary to construct the hydraulic barrier at the upper and sides of the vault, and that, for this case, achieving design hydraulic properties of bentonite/sand mixture barrier in the as-built condition is crucial to limit the seepage into the waste

  9. Determination of near field excavation disturbance in crystalline rock

    International Nuclear Information System (INIS)

    Koopmans, R.; Hughes, R.W.

    1986-01-01

    The computerized dilatometer system has rapidly and economically provided deformation moduli of low and high modulus rock, determined the extent of excavation disturbance surrounding an underground opening and located open fracture within a rock mass. Results from both test sites indicate that the moduli obtained were influenced by the in situ tangential stress field. It has been shown that the near field excavation disturbance is kept to a minimum through the use of careful excavation techniques such as the tunnel boring machine. In turn, the in situ tangential stress levels and deformation moduli are maximized while the corresponding permeability is minimized

  10. [Transmission efficiency analysis of near-field fiber probe using FDTD simulation].

    Science.gov (United States)

    Huang, Wei; Dai, Song-Tao; Wang, Huai-Yu; Zhou, Yun-Song

    2011-10-01

    A fiber probe is the key component of near-field optical technology which is widely used in high resolution imaging, spectroscopy detection and nano processing. How to improve the transmission efficiency of the fiber probe is a very important problem in the application of near-field optical technology. Based on the results of 3D-FDTD computation, the dependence of the transmission efficiency on the cone angle, the aperture diameter, the wavelength and the thickness of metal cladding is revealed. The authors have also made a comparison between naked probe and the probe with metal cladding in terms of transmission efficiency and spatial resolution. In addition, the authors have discovered the fluctuation phenomena of transmission efficiency as the wavelength of incident laser increases.

  11. Active control of near-field radiative heat transfer between graphene-covered metamaterials

    Science.gov (United States)

    Zhao, Qimei; Zhou, Ting; Wang, Tongbiao; Liu, Wenxing; Liu, Jiangtao; Yu, Tianbao; Liao, Qinghua; Liu, Nianhua

    2017-04-01

    In this study, the near-field radiative heat transfer between graphene-covered metamaterials is investigated. The electric surface plasmons (SPs) supported by metamaterials can be coupled with the SPs supported by graphene. The near-field heat transfer between the graphene-covered metamaterials is significantly larger than that between metamaterials because of the strong coupling in our studied frequency range. The relationship between heat flux and chemical potential is studied for different vacuum gaps. Given that the chemical potential of graphene can be tuned by the external electric field, heat transfer can be actively controlled by modulating the chemical potential. The heat flux for certain vacuum gaps can reach a maximum value when the chemical potential is at a particular value. The results of this study are beneficial for actively controlling energy transfer.

  12. Active control of near-field radiative heat transfer between graphene-covered metamaterials

    International Nuclear Information System (INIS)

    Zhao, Qimei; Zhou, Ting; Wang, Tongbiao; Liu, Wenxing; Liu, Jiangtao; Yu, Tianbao; Liao, Qinghua; Liu, Nianhua

    2017-01-01

    In this study, the near-field radiative heat transfer between graphene-covered metamaterials is investigated. The electric surface plasmons (SPs) supported by metamaterials can be coupled with the SPs supported by graphene. The near-field heat transfer between the graphene-covered metamaterials is significantly larger than that between metamaterials because of the strong coupling in our studied frequency range. The relationship between heat flux and chemical potential is studied for different vacuum gaps. Given that the chemical potential of graphene can be tuned by the external electric field, heat transfer can be actively controlled by modulating the chemical potential. The heat flux for certain vacuum gaps can reach a maximum value when the chemical potential is at a particular value. The results of this study are beneficial for actively controlling energy transfer. (paper)

  13. The measurement of in-situ stress in near surface environments

    International Nuclear Information System (INIS)

    Garritty, P.; Irvin, R.A.

    1984-04-01

    One of the major unknowns affecting aspects of underground construction and the geohydrology of rock masses is the magnitude and direction of the geostatic principal stresses in the earth's crust. This is particularly the case in near surface rocks where there are indications that high horizontal stresses may exist. The measurement of stress in near surface environments is particularly difficult. The techniques, experience and results of a geostatic stress measurement programme using four commercially available devices at shallow depth in the Carnmenellis Granite are critically discussed and compared. This report also brings together some of the conclusions of two previous reports in the series, Garritty (1983) and Garritty and Irvin (1983), and emphasises the fundamental relationship between the state of stress in the earth's crust and the geohydrology of rock masses. (author)

  14. Interior near-field acoustical holography in flight.

    Science.gov (United States)

    Williams, E G; Houston, B H; Herdic, P C; Raveendra, S T; Gardner, B

    2000-10-01

    In this paper boundary element methods (BEM) are mated with near-field acoustical holography (NAH) in order to determine the normal velocity over a large area of a fuselage of a turboprop airplane from a measurement of the pressure (hologram) on a concentric surface in the interior of the aircraft. This work represents the first time NAH has been applied in situ, in-flight. The normal fuselage velocity was successfully reconstructed at the blade passage frequency (BPF) of the propeller and its first two harmonics. This reconstructed velocity reveals structure-borne and airborne sound-transmission paths from the engine to the interior space.

  15. Local field distribution near corrugated interfaces: Green function formalism versus effective medium theory

    International Nuclear Information System (INIS)

    Choy, C.W.; Xiao, J.J.; Yu, K.W.

    2007-01-01

    The recent Green function formalism (GFF) has been used to study the local field distribution near a periodic interface separating two homogeneous media of different dielectric constants. In the GFF, the integral equations can be solved conveniently because of the existence of an analytic expression for the kernel (Greenian). However, due to a severe singularity in the Greenian, the formalism was formerly applied to compute the electric fields away from the interface region. In this work, we have succeeded in extending the GFF to compute the electric field inside the interface region by taking advantage of a sum rule. To our surprise, the strengths of the electric fields are quite similar in both media across the interface, despite of the large difference in dielectric constants. Moreover, we propose a simple effective medium approximation (EMA) to compute the electric field inside the interface region. We show that the EMA can indeed give an excellent description of the electric field, except near a surface plasmon resonance

  16. Reciprocity Method for Obtaining the Far Fields Generated by a Source Inside or Near a Microparticle

    National Research Council Canada - National Science Library

    Hill, Steven

    1997-01-01

    We show that the far fields generated by a source inside or near a microparticle can be obtained readily by using the reciprocity theorem along with the internal or near fields generated by plane wave illumination...

  17. Testing the near field/far field model performance for prediction of particulate matter emissions in a paint factory

    DEFF Research Database (Denmark)

    Koivisto, A.J.; Jensen, A.C.Ø.; Levin, Marcus

    2015-01-01

    A Near Field/Far Field (NF/FF) model is a well-accepted tool for precautionary exposure assessment but its capability to estimate particulate matter (PM) concentrations is not well studied. The main concern is related to emission source characterization which is not as well defined for PM emitters...

  18. Terahertz-wave near-field imaging with subwavelength resolution using surface-wave-assisted bow-tie aperture

    Science.gov (United States)

    Ishihara, Kunihiko; Ohashi, Keishi; Ikari, Tomofumi; Minamide, Hiroaki; Yokoyama, Hiroyuki; Shikata, Jun-ichi; Ito, Hiromasa

    2006-11-01

    We demonstrate the terahertz-wave near-field imaging with subwavelength resolution using a bow-tie shaped aperture surrounded by concentric periodic structures in a metal film. A subwavelength aperture with concentric periodic grooves, which are known as a bull's eye structure, shows extremely large enhanced transmission beyond the diffraction limit caused by the resonant excitation of surface waves. Additionally, a bow-tie aperture exhibits extraordinary field enhancement at the sharp tips of the metal, which enhances the transmission and the subwavelength spatial resolution. We introduced a bow-tie aperture to the bull's eye structure and achieved high spatial resolution (˜λ/17) in the near-field region. The terahertz-wave near-field image of the subwavelength metal pattern (pattern width=20μm) was obtained for the wavelength of 207μm.

  19. Meshed doped silicon photonic crystals for manipulating near-field thermal radiation

    Science.gov (United States)

    Elzouka, Mahmoud; Ndao, Sidy

    2018-01-01

    The ability to control and manipulate heat flow is of great interest to thermal management and thermal logic and memory devices. Particularly, near-field thermal radiation presents a unique opportunity to enhance heat transfer while being able to tailor its characteristics (e.g., spectral selectivity). However, achieving nanometric gaps, necessary for near-field, has been and remains a formidable challenge. Here, we demonstrate significant enhancement of the near-field heat transfer through meshed photonic crystals with separation gaps above 0.5 μm. Using a first-principle method, we investigate the meshed photonic structures numerically via finite-difference time-domain technique (FDTD) along with the Langevin approach. Results for doped-silicon meshed structures show significant enhancement in heat transfer; 26 times over the non-meshed corrugated structures. This is especially important for thermal management and thermal rectification applications. The results also support the premise that thermal radiation at micro scale is a bulk (rather than a surface) phenomenon; the increase in heat transfer between two meshed-corrugated surfaces compared to the flat surface (8.2) wasn't proportional to the increase in the surface area due to the corrugations (9). Results were further validated through good agreements between the resonant modes predicted from the dispersion relation (calculated using a finite-element method), and transmission factors (calculated from FDTD).

  20. Fabrication of sub-diffraction-limit molecular structures by scanning near-field photolithography

    Science.gov (United States)

    Ducker, Robert E.; Montague, Matthew T.; Sun, Shuqing; Leggett, Graham J.

    2007-09-01

    Using a scanning near-field optical microscope coupled to a UV laser, an approach we term scanning near-field photolithography (SNP), structures as small as 9 nm (ca. λ/30) may be fabricated in self-assembled monolayers of alkanethiols on gold surfaces. Selective exposure of the adsorbate molecules in the near field leads to photoconversion of the alkylthiolate to a weakly bound alkylsulfonate which may be displaced readily be a contrasting thiol, leading to a chemical pattern, or used as a resist for the selective etching of the underlying metal. A novel ultra-mild etch for gold is reported, and used to etch structures as small as 9 nm. Photopatterning of oligo(ethylene glycol) (OEG) terminated selfassembled monolayers facilitates the fabrication of biomolecular nanostructures. Selective removal of the protein-resistant OEG terminated adsorbates created regions that may be functionalized with a second thiol and derivatized with a biomolecule. Finally, the application of SNP to nanopatterning on oxide surfaces is demonstrated. Selective exposure of monolayers of phosphonic acids adsorbed onto aluminum oxide leads to cleavage of the P-C bond and desorption of the adsorbate molecule. Subsequent etching, using aqueous based, yields structures as small as 100 nm.

  1. Apertureless near-field scanning optical microscope working with or without laser source.

    Science.gov (United States)

    Formanek, F; De Wilde, Y; Aigouy, L; Chen, Y

    2004-01-01

    An apertureless near-field scanning optical microscope (ANSOM), used indifferent configurations, is presented. Our versatile home-made setup, based on a sharp tungsten tip glued onto a quartz tuning fork and working in tapping mode, allows to perform imaging over a broad spectral range. We have recorded optical images in the visible (wavelength, lambda = 655 nm) and in the infrared (lambda = 10.6 microm), proving that the setup routinely achieves an optical resolution of images recorded in the visible (lambda = 655 nm) in an inverted configuration where the tip does not perturb the focused spot of the illumination laser. Approach curves as well as image profiles have revealed that on demodulating the optical signal at higher harmonics, we can obtain an effective probe sharpening which results in an improvement of the resolution. Finally, we have presented optical images recorded in the infrared without any illumination, that is, the usual laser source is replaced by a simple heating of the sample. This has shown that the ANSOM can be used as a near-field thermal optical microscope (NTOM) to probe the near field generated by the thermal emission of the sample.

  2. Time-resolved ultraviolet near-field scanning optical microscope for characterizing photoluminescence lifetime of light-emitting devices.

    Science.gov (United States)

    Park, Kyoung-Duck; Jeong, Hyun; Kim, Yong Hwan; Yim, Sang-Youp; Lee, Hong Seok; Suh, Eun-Kyung; Jeong, Mun Seok

    2013-03-01

    We developed a instrument consisting of an ultraviolet (UV) near-field scanning optical microscope (NSOM) combined with time-correlated single photon counting, which allows efficient observation of temporal dynamics of near-field photoluminescence (PL) down to the sub-wavelength scale. The developed time-resolved UV NSOM system showed a spatial resolution of 110 nm and a temporal resolution of 130 ps in the optical signal. The proposed microscope system was successfully demonstrated by characterizing the near-field PL lifetime of InGaN/GaN multiple quantum wells.

  3. Distribution of local magnetic field of vortex lattice near anisotropic superconductor surface in inclined external fields

    International Nuclear Information System (INIS)

    Efremova, S.A.; Tsarevskij, S.L.

    1997-01-01

    Magnetic field distribution in a unit cell of the Abrikosov vortex lattice near the surface of monoaxial anisotropic type-ii superconductors in inclined external magnetic field has been found in the framework of London model for the cases when the symmetry axis is perpendicular and parallel to the superconductor surface interface. Distribution of local magnetic field as a function of the distance from the superconductor interface surface and external field inclination angle has been obtained. Using high-Tc superconductor Y-Ba-Cu-O by way of examples, it has been shown that the study of local magnetic field distribution function, depending on external magnetic field inclination angle towards the superconductor symmetry axis and towards the superconductor surface, can provide important data on anisotropic properties of the superconductor [ru

  4. Radionuclide transport in the repository near-field and far-field

    International Nuclear Information System (INIS)

    Poteri, A.; Nordman, H.; Pulkkanen, V.-M.; Smith, P.

    2014-01-01

    This report is a background report of the TURVA-2012 safety case report 'Assessment of Radionuclide Release Scenarios for the Repository System'. This report gives a comprehensive account of the modelling of radionuclide release from a defective canister and the subsequent migration to the surface groundwater system. The focus of this report is in the radionuclide migration both in the repository near-field and in the repository far-field. Radionuclide releases from the canister and migration through the repository near-field and far-field have also been analysed in the probabilistic sensitivity analysis based on the Monte Carlo simulation method. Those simulations are discussed in a separate report by Cormenzana. Calculation cases are derived from three different types of scenarios: (i) The base scenario that assumes a single initially defective canister located in a cautiously selected canister position, i.e. selecting the failed canister location such that radionuclide release and transport properties are conservative compared to the statistics over all canister locations. Migration processes and parameter values follow the most likely lines of evolution. Repository safety functions are assumed to perform according to the design basis. Calculation cases defined in the Assessment of Radionuclide Release Scenarios report are also supplemented by additional calculation cases that are aimed to study variability between different DFN realisations (additional BS-ALL cases), longitudinal dispersion (BS-RC-ld cases) and alternative realisations of the transport classes along the release paths (BS-RC-tc cases), (ii) Variant scenarios that study declined performance of the repository safety functions. These include enhanced corrosion failure and degradation of the buffer under variant geochemical conditions (iii) Disturbance scenarios that analyse influences of unlikely events on the radionuclide release and migration. Analysis of the variant and disturbance scenarios

  5. Topography characterization of a deep grating using near-field imaging

    DEFF Research Database (Denmark)

    Gregersen, Niels; Tromborg, Bjarne; Volkov, Valentyn S.

    2006-01-01

    Using near-field optical microscopy at the wavelength of 633 nm, we image light intensity distributions at several distances above an ~2-mm deep and a 1-mm-period glass grating illuminated from below under the condition of total internal reflection. The intensity distributions are numerically mod...

  6. Room-temperature near-field reflection spectroscopy of single quantum wells

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Hvam, Jørn Marcher; Madsen, Steen

    1997-01-01

    . This technique suppresses efficiently the otherwise dominating far-field background and reduces topographic artifacts. We demonstrate its performance on a thin, strained near-surface CdS/ZnS single quantum well at room temperature. The optical structure of these topographically flat samples is due to Cd...

  7. Effects of the near field on source-independent q estimation

    NARCIS (Netherlands)

    Shigapov, R.; Kashtan, B.; Droujinine, A.; Mulder, W.A.

    2013-01-01

    We consider the problem of Q estimation from microseismic and from perforation shot data. Assuming that the source wavelet is not well known, we focused on the spectral ratio method and on source-independent viscoelastic full waveform inversion. We derived 3-D near-field approximations of monopole

  8. Directivity of Spherical Polyhedron Sound Source Used in Near-Field HRTF Measurements

    International Nuclear Information System (INIS)

    Yu Guang-Zheng; Xie Bo-Sun; Rao Dan

    2010-01-01

    The omnidirectional character is one of important requirements for the sound source used in near-field head-related transfer function (HRTF) measurements. Based on the analysis on the radiation sound pressure and directivity character of various spherical polyhedron sound sources, a spherical dodecahedral sound source with radius of 0.035m is proposed and manufactured. Theoretical and measured results indicate that the sound source is approximately omnidirectional below the frequency of 8 kHz. In addition, the sound source has reasonable magnitude response from 350Hz to 20kHz and linear phase characteristics. Therefore, it is suitable for the near-field HRTF measurements. (fundamental areas of phenomenology(including applications))

  9. Toehold-mediated internal control to probe the near-field interaction between the metallic nanoparticle and the fluorophore

    Science.gov (United States)

    Ang, Y. S.; Yung, L. Y. L.

    2014-10-01

    Metallic nanoparticles (MNPs) are known to alter the emission of vicinal fluorophores through the near-field interaction, leading to either fluorescence quenching or enhancement. Much ambiguity remains in the experimental outcome of such a near-field interaction, particularly for bulk colloidal solution. It is hypothesized that the strong far-field interference from the inner filter effect of the MNPs could mask the true near-field MNP-fluorophore interaction significantly. Thus, in this work, a reliable internal control capable of decoupling the near-field interaction from far-field interference is established by the use of the DNA toehold concept to mediate the in situ assembly and disassembly of the MNP-fluorophore conjugate. A model gold nanoparticle (AuNP)-Cy3 system is used to investigate our proposed toehold-mediated internal control system. The maximum fluorescence enhancement is obtained for large-sized AuNP (58 nm) separated from Cy3 at an intermediate distance of 6.8 nm, while fluorescence quenching is observed for smaller-sized AuNP (11 nm and 23 nm), which is in agreement with the theoretical values reported in the literature. This work shows that the toehold-mediated internal control design can serve as a central system for evaluating the near-field interaction of other MNP-fluorophore combinations and facilitate the rational design of specific MNP-fluorophore systems for various applications.Metallic nanoparticles (MNPs) are known to alter the emission of vicinal fluorophores through the near-field interaction, leading to either fluorescence quenching or enhancement. Much ambiguity remains in the experimental outcome of such a near-field interaction, particularly for bulk colloidal solution. It is hypothesized that the strong far-field interference from the inner filter effect of the MNPs could mask the true near-field MNP-fluorophore interaction significantly. Thus, in this work, a reliable internal control capable of decoupling the near-field

  10. Technetium getters in the near surface environment

    International Nuclear Information System (INIS)

    Krumhansl, James L.; Zhang, Pengchu; Westrich, Henry R.; Bryan, Charles R.; Molecke, Martin A.

    2000-01-01

    Conventional performance assessments assume that radioactive 99 Tc travels as a non-sorbing component with an effective K d (distribution coefficient) of 0. This is because soil mineral surfaces commonly develop net negative surface charges and pertechnetate (TcO 4 ), with large ionic size and low electrical density, is not sorbed onto them. However, a variety of materials have been identified that retain Tc and may eventually lead to promising Tc getters. In assessing Tc getter performance it is important to evaluate the environment in which the getter is to function. In many contaminant plumes Tc will only leach slowly from the source of the contamination and significant dilution is likely. Thus, sub-ppb Tc concentrations are expected and normal groundwater constituents will dominate the aquifer chemistry. In this setting a variety of constituents were found to retard TcO 4 : imogolite, boehmite, hydrotalcite, goethite, copper sulfide and oxide and coal. Near leaking tanks of high level nuclear waste, Tc may be present in mg/L level concentrations and groundwater chemistry will be dominated by constituents from the waste. Both bone char, and to a lesser degree, freshly precipitated Al hydroxides may be effective Tc scavengers in this environment. Thus, the search for Tc getters is far from hopeless, although much remains to be learned about the mechanisms by which these materials retain Tc

  11. Baseline geochemistry of soil and bedrock Tshirege Member of the Bandelier Tuff at MDA-P

    International Nuclear Information System (INIS)

    Warren, R.G.; McDonald, E.V.; Ryti, R.T.

    1997-08-01

    This report provides baseline geochemistry for soils (including fill), and for bedrock within three specific areas that are planned for use in the remediation of Material Disposal Area P (MDA-P) at Technical Area 16 (TA-16). The baseline chemistry includes leachable element concentrations for both soils and bedrock and total element concentrations for all soil samples and for two selected bedrock samples. MDA-P operated from the early 1950s to 1984 as a landfill for rubble and debris generated by the burning of high explosives (HE) at the TA-16 Burning Ground, HE-contaminated equipment and material, barium nitrate sand, building materials, and trash. The aim of this report is to establish causes for recognizable chemical differences between the background and baseline data sets. In many cases, the authors conclude that recognizable differences represent natural enrichments. In other cases, differences are best attributed to analytical problems. But most importantly, the comparison of background and baseline geochemistry demonstrates significant contamination for several elements not only at the two remedial sites near the TA-16 Burning Ground, but also within the entire region of the background study. This contamination is highly localized very near to the surface in soil and fill, and probably also in bedrock; consequently, upper tolerance limits (UTLs) calculated as upper 95% confidence limits of the 95th percentile are of little value and thus are not provided. This report instead provides basic statistical summaries and graphical comparisons for background and baseline samples to guide strategies for remediation of the three sites to be used in the restoration of MDA-P

  12. Near-field acoustic imaging based on Laplacian sparsity

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Daudet, Laurent

    2016-01-01

    We present a sound source identification method for near-field acoustic imaging of extended sources. The methodology is based on a wave superposition method (or equivalent source method) that promotes solutions with sparse higher order spatial derivatives. Instead of promoting direct sparsity......, and the validity of the wave extrapolation used for the reconstruction is examined. It is shown that this methodology can overcome conventional limits of spatial sampling, and is therefore valid for wide-band acoustic imaging of extended sources....

  13. Students attendance monitoring using near field communication technology

    OpenAIRE

    Stakėnas, Tautvydas

    2017-01-01

    Today, near field communication technology (NFC) is one of the most popular automatic identification technologies. There is a lot of research and development in this area trying to make as much use of this technology as possible, and in coming years many new applications and research areas will continue to appear. In this paper the author examines NFC technology application for student’s attendance monitoring. In the first part of the thesis NFC uses, application methods and security levels a...

  14. Near-Earth Magnetic Field Effects of Large-Scale Magnetospheric Currents

    DEFF Research Database (Denmark)

    Lühr, Hermann; Xiong, Chao; Olsen, Nils

    2017-01-01

    . Significant progress in interpreting the magnetic fields from the different sources has been achieved thanks to magnetic satellite missions like Ørsted, CHAMP and now Swarm. Of particular interest for this article is a proper representation of the magnetospheric ring current effect. Uncertainties in modelling...... its effect still produce the largest residuals between observations and present-day geomagnetic field models. A lot of progress has been achieved so far, but there are still open issues like the characteristics of the partial ring current. Other currents discussed are those flowing......Magnetospheric currents play an important role in the electrodynamics of near-Earth space. This has been the topic of many space science studies. Here we focus on the magnetic fields they cause close to Earth. Their contribution to the geomagnetic field is the second largest after the core field...

  15. Curved laser microjet in near field.

    Science.gov (United States)

    Kotlyar, Victor V; Stafeev, Sergey S; Kovalev, Alexey A

    2013-06-20

    With the use of the finite-difference time-domain-based simulation and a scanning near-field optical microscope that has a metal cantilever tip, the diffraction of a linearly polarized plane wave of wavelength λ by a glass corner step of height 2λ is shown to generate a low divergence laser jet of a root-parabolic form: over a distance of 4.7λ on the optical axis, the beam path is shifted by 2.1λ. The curved laser jet of the FWHM length depth of focus=9.5λ has the diameter FWHM=1.94λ over the distance 5.5λ, and the intensity maximum is 5 times higher than the incident wave intensity. The discrepancy between the analytical and the experimental results amounts to 11%.

  16. Measurement of incident sound power using near field acoustic holography

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Tiana Roig, Elisabet

    2009-01-01

    ; and it has always been regarded as impossible to measure the sound power that is incident on a wall directly. This paper examines a new method of determining this quantity from sound pressure measurements at positions on the wall using ‘statistically optimised near field acoustic holography’ (SONAH...

  17. Finite Element Method Simulations of the Near-Field Enhancement at the Vicinity of Fractal Rough Metallic Surfaces

    International Nuclear Information System (INIS)

    Micic, Miodrag; Klymyshyn, Nicholas A.; Lu, H Peter

    2004-01-01

    Near-field optical enhancement at metal surfaces and methods such as surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), fluorescent quenching and enhancement, and various near-field scanning microscopies (NSOM) all depend on a metals surface properties, mainly on its morphology and SPR resonant frequency. We report on simulations of the influence of different surface morphologies on electromagnetic field enhancements at the rough surfaces of noble metals and also evaluate the optimal conditions for the generation of a surface-enhanced Raman signal of absorbed species on a metallic substrate. All simulations were performed with a classical electrodynamics approach using the full set of Maxwells equations, which were solved with the three-dimensional finite element method (FEM). Two different classes of surfaces where modeled using fractals, representing diffusion limited aggregation growth dendritic structures, such as one on the surface of electrodes, and second one representing the sponge-like structure used to model surfaces of particles with high porosity, such as metal coated catalyst supports. The simulations depict the high inhomogeneity of an enhanced electromagnetic field as both a field enhancement and field attenuation near the surface. While the diffusion limited aggregation dendritical fractals enhanced the near-field electromagnetic field, the sponge fractals significantly reduced the local electromagnetic field intensity. Moreover, the fractal orders of the fractal objects did not significantly alter the total enhancement, and the distribution of a near-field enhancement was essentially invariant to the changes in the angle of an incoming laser beam

  18. Is the environment near school associated with active commuting to school among preschoolers?

    Directory of Open Access Journals (Sweden)

    Jose Cazuza Farias Junior

    2013-05-01

    Full Text Available Available studies show that environmental factors may influence how parentes choose to commute their children from home to school. Thus, the aim of this study was to analyze the association between the characteristics of the physical and social environment near school and active commuting to school among preschool children. A school-based cross-sectional study with a sample of children aged 3to 5 years (n=914 was undertaken. Participants were selected by a single-stage cluster sampling process. To obtain data on commuting to school and demographicand socioeconomic variables, a previously validated questionnaire was used while an audit tool was used to assess the environment near school. Binarylogistic regression was used to analyze the association and results were presented as Odds Ratio values. Results showed that 28.3% (95%CI 25.5-31.3 ofthe children were active commuters from home to school. A positive association was found between public transportation (p=0.002 and social environment(p=0.004 domains and active commuting. However, this association was foundonly among children from families that did not have a car. The likelihood of achild being an active commuter was higher among those who are enrolled in schools with better environmental surroundings (OR=1.88; 95%CI 1.31-2.70. It was concluded that there was a positive association between some of the environmental factors near school and active commuting to school among children from families that did not have a car.

  19. Direct measurement of source RDP's and yields from near-field Soviet seismic data. Final report

    International Nuclear Information System (INIS)

    Saikia, C.K.; McLaren, J.P.; Helmberger, D.V.

    1994-01-01

    The objective of this study was to investigate the source characteristics represented in the form of a reduced displacement potential (RDP) of Soviet nuclear explosions and was based on the availability of in-country near-field data. At the start of the project, it was thought that data would be readily accessible to us with the start of the open exchange of seismic data between the US and the Soviet Union. In fact, we did receive near-field waveforms of two Soviet nuclear explosions from Azghir test site near the Caspian Sea following which the transfer of data stopped till the end of the project. Consequently, the research effort was descoped. Only recently, some additional data have become available at CSS (Center for Seismic Studies). We have undertaken a thorough investigation of the limited data available from a large coupled shot (64 kT) in Azghir followed five years later by a decoupled shot (8 kT). We have successfully modeled the near-field data from these events to determine their source RDP's and establish a decoupling factor of 15 using a time-domain waveform modeling technique. The results of this study are presented in the enclosed manuscript: Analysis of near-field data from a Soviet decoupling experiment

  20. Study on the system development for evaluating long-term alteration of hydraulic field in Near Field 2

    International Nuclear Information System (INIS)

    Okutu, Kazuo; Morikawa, Seiji; Takamura, Hisashi

    2003-02-01

    For the high performance evaluation of reliability of TRU waste repository, the system development for evaluating long-term alteration in consideration of the changes action of barrier materials of hydraulic field in Near Field is required. In this research, the system development for evaluating long-term alteration of hydraulic field in Near Field was examined. The model evaluating each phenomena and the prototype system for chemical/mechanical analysis system were developed, and the method of coupling chemical with dynamic analysis was examined. To improve accuracy and propriety of this analysis system in the future, necessary development elements were arranged. The research result of this year is shown below. 1) Knowledge concerning the chemical phenomena in the near field evolution was rearranged. Experimental approaches and analysis methods were applied to the phenomena of which the knowledge can be obtained. Approaches to focus the model were applied to the phenomena for which knowledge is essentially difficult to obtain. The analysis model was improved using knowledge from natural analog and computational analyses. An analysis system was developed and the propriety of the model was demonstrated. 2) The model of bentonite material was developed by focusing attention on nonlinear swelling behavior. And the model of cement material was developed by focusing attention on deformation behavior influenced by leaching of calcium element which cause reducing of rigidity and strength. With regard to the bentonite model, to testify its propriety, the trial analysis result compared with the consolidation properties test data. Furthermore, the dynamic alteration action analysis system consisted of bentonite and cement model was developed, and trial analysis was performed. In this trial analysis, parameters of cation exchange ratio of Na-bentonite for Ca ion and leaching ratio of Ca from cement material were considered. On the one hand, as concerns rock, to include the

  1. Near field evidence of backward surface plasmon polaritons on negative index material boundaries

    International Nuclear Information System (INIS)

    Cuevas, Mauro; Grunhut, Vivian; Depine, Ricardo A.

    2016-01-01

    Highlights: • Electromagnetic scattering from a localized defect on a NIM surface is presented. • The electromagnetic response strongly depends on the SPPs excited. • Near field distribution reveals the forward or backward character of SPPs excited. - Abstract: We present a detailed analysis about the electromagnetic response of a metamaterial surface with a localized defect. The excitation of electromagnetic surface waves leads to a near-field distribution showing a periodic dependence along the metamaterial surface. We find that this periodic pattern provides a direct demonstration of the forward or backward surface wave propagation.

  2. Near field evidence of backward surface plasmon polaritons on negative index material boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas, Mauro, E-mail: cuevas@df.uba.ar [Facultad de Ingeniería y Tecnología Informática, Universidad de Belgrano, Villanueva 1324, C1426BMJ, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Grunhut, Vivian [Facultad de Ingeniería, Universidad Austral (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Depine, Ricardo A. [Grupo de Electromagnetismo Aplicado, Departamento de Física, FCEN, Universidad de Buenos Aires and IFIBA, Ciudad Universitaria, Pabellón I, C1428EHA, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina)

    2016-12-09

    Highlights: • Electromagnetic scattering from a localized defect on a NIM surface is presented. • The electromagnetic response strongly depends on the SPPs excited. • Near field distribution reveals the forward or backward character of SPPs excited. - Abstract: We present a detailed analysis about the electromagnetic response of a metamaterial surface with a localized defect. The excitation of electromagnetic surface waves leads to a near-field distribution showing a periodic dependence along the metamaterial surface. We find that this periodic pattern provides a direct demonstration of the forward or backward surface wave propagation.

  3. Shape matters: Near-field fluid mechanics dominate the collective motions of ellipsoidal squirmers.

    Science.gov (United States)

    Kyoya, K; Matsunaga, D; Imai, Y; Omori, T; Ishikawa, T

    2015-12-01

    Microswimmers show a variety of collective motions. Despite extensive study, questions remain regarding the role of near-field fluid mechanics in collective motion. In this paper, we describe precisely the Stokes flow around hydrodynamically interacting ellipsoidal squirmers in a monolayer suspension. The results showed that various collective motions, such as ordering, aggregation, and whirls, are dominated by the swimming mode and the aspect ratio. The collective motions are mainly induced by near-field fluid mechanics, despite Stokes flow propagation over a long range. These results emphasize the importance of particle shape in collective motion.

  4. Evanescent field characterisation for a d-shaped optical fibre using scanning near-field optical microscopy

    International Nuclear Information System (INIS)

    Huntington, S.T.; Nugent, K.A.; Roberts, A.; Mulvaney, P.; Lo, K.M.

    1997-01-01

    Scanning near field optical microscopy is used to measure the evanescent filed and mode profile of a Ge-doped D-shaped optical fibre. The structure of the fibre is determined by differential etching followed by an investigation of the resultant topography with an atomic force microscope. This information is then used to theoretically model the expected behaviour of the fibre and it is shown that the theoretically model the expected behaviour of the fibre and it is shown that the theoretical results are in excellent agreement with the experimentally observed fields

  5. Visualizing Complex Environments in the Geo- and BioSciences

    Science.gov (United States)

    Prabhu, A.; Fox, P. A.; Zhong, H.; Eleish, A.; Ma, X.; Zednik, S.; Morrison, S. M.; Moore, E. K.; Muscente, D.; Meyer, M.; Hazen, R. M.

    2017-12-01

    Earth's living and non-living components have co-evolved for 4 billion years through numerous positive and negative feedbacks. Earth and life scientists have amassed vast amounts of data in diverse fields related to planetary evolution through deep time-mineralogy and petrology, paleobiology and paleontology, paleotectonics and paleomagnetism, geochemistry and geochrononology, genomics and proteomics, and more. Integrating the data from these complimentary disciplines is very useful in gaining an understanding of the evolution of our planet's environment. The integrated data however, represent many extremely complex environments. In order to gain insights and make discoveries using this data, it is important for us to model and visualize these complex environments. As part of work in understanding the "Co-Evolution of Geo and Biospheres using Data Driven Methodologies," we have developed several visualizations to help represent the information stored in the datasets from complimentary disciplines. These visualizations include 2D and 3D force directed Networks, Chord Diagrams, 3D Klee Diagrams. Evolving Network Diagrams, Skyline Diagrams and Tree Diagrams. Combining these visualizations with the results of machine learning and data analysis methods leads to a powerful way to discover patterns and relationships about the Earth's past and today's changing environment.

  6. Analysis of near-field components of a plasmonic optical antenna and their contribution to quantum dot infrared photodetector enhancement.

    Science.gov (United States)

    Gu, Guiru; Vaillancourt, Jarrod; Lu, Xuejun

    2014-10-20

    In this paper, we analyze near-field vector components of a metallic circular disk array (MCDA) plasmonic optical antenna and their contribution to quantum dot infrared photodetector (QDIP) enhancement. The near-field vector components of the MCDA optical antenna and their distribution in the QD active region are simulated. The near-field overlap integral with the QD active region is calculated at different wavelengths and compared with the QDIP enhancement spectrum. The x-component (E(x)) of the near-field vector shows a larger intensity overlap integral and stronger correlation with the QDIP enhancement than E(z) and thus is determined to be the major near-field component to the QDIP enhancement.

  7. Depositional environment of near-surface sediments, King George Basin, Bransfield Strait, Antarctica

    Science.gov (United States)

    Yoon, H. I.; Park, B. K.; Chang, S. K.; Han, M. W.; Oh, J. K.

    1994-03-01

    Four sediment cores were collected to determine the depositional environments of the King George Basin northeast of Bransfield Strait, Antarctica. The cored section revealed three distinct lithofacies: laminated siliceous ooze derived from an increased paleoproductivity near the receding sea-ice edges, massive muds that resulted from hemipelagic sedimentation in open water, and graded sediments that originated from nearby local seamounts by turbidity currents. Clay mineral data of the cores indicate a decreasing importance of volcanic activity through time. Active volcanism and hydrothermal activity appear to be responsible for the enrichment of smectite near the Penguin and Bridgeman Islands.

  8. Fuel density effect on near nozzle flow field in small laminar coflow diffusion flames

    KAUST Repository

    Xiong, Yuan

    2015-01-01

    Flow characteristics in small coflow diffusion flames were investigated with a particular focus on the near-nozzle region and on the buoyancy force exerted on fuels with densities lighter and heavier than air (methane, ethylene, propane, and n-butane). The flow-fields were visualized through the trajectories of seed particles. The particle image velocimetry technique was also adopted for quantitative velocity field measurements. The results showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle, emphasizing the importance of the relative density of the fuel to that of the air on the flow-field. Nozzle heating influenced the near-nozzle flow-field particularly among lighter fuels (methane and ethylene). Numerical simulations were also conducted, focusing specifically on the effect of specifying inlet boundary conditions for fuel. The results showed that a fuel inlet boundary with a fully developed velocity profile for cases with long tubes should be specified inside the fuel tube to permit satisfactory prediction of the flow-field. The calculated temperature fields also indicated the importance of the selection of the location of the inlet boundary, especially in testing various combustion models that include soot in small coflow diffusion flames. © 2014 The Combustion Institute.

  9. Gravitational and electromagnetic fields near an anti-de Sitter-like infinity

    International Nuclear Information System (INIS)

    Krtous, Pavel; Podolsky, Jiri

    2004-01-01

    We analyze the asymptotic structure of general gravitational and electromagnetic fields near an anti-de Sitter-like conformal infinity. The dependence of the radiative component of the fields on a null direction along which the infinity is approached is obtained. The directional pattern of outgoing and ingoing radiation, which supplements standard peeling property, is determined by the algebraic (Petrov) type of the fields and also by the orientation of the principal null directions with respect to timelike infinity. The dependence on the orientation is a new feature if compared to spacelike infinity

  10. Near-field acoustic holography with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    of the particle velocity has notable potential in NAH, and furthermore, combined measurement of sound pressure and particle velocity opens a new range of possibilities that are examined in this study. On this basis, sound field separation methods have been studied, and a new measurement principle based on double...... layer measurements of the particle velocity has been proposed. Also, the relation between near-field and far-field radiation from sound sources has been examined using the concept of the supersonic intensity. The calculation of this quantity has been extended to other holographic methods, and studied...

  11. High energy near- and far-field ptychographic tomography at the ESRF

    Science.gov (United States)

    da Silva, Julio C.; Haubrich, Jan; Requena, Guillermo; Hubert, Maxime; Pacureanu, Alexandra; Bloch, Leonid; Yang, Yang; Cloetens, Peter

    2017-09-01

    In high-resolution tomography, one needs high-resolved projections in order to reconstruct a high-quality 3D map of a sample. X-ray ptychography is a robust technique which can provide such high-resolution 2D projections taking advantage of coherent X-rays. This technique was used in the far-field regime for a fair amount of time, but it can now also be implemented in the near-field regime. In both regimes, the technique enables not only high-resolution imaging, but also high sensitivity to the electron density of the sample. The combination with tomography makes 3D imaging possible via ptychographic X-ray computed tomography (PXCT), which can provide a 3D map of the complex-valued refractive index of the sample. The extension of PXCT to X-ray energies above 15 keV is challenging, but it can allow the imaging of object opaque to lower energy. We present here the implementation and developments of high-energy near- and far-field PXCT at the ESRF.

  12. Near-field multiple traps of paraxial acoustic vortices with strengthened gradient force generated by sector transducer array

    Science.gov (United States)

    Wang, Qingdong; Li, Yuzhi; Ma, Qingyu; Guo, Gepu; Tu, Juan; Zhang, Dong

    2018-01-01

    In order to improve the capability of particle trapping close to the source plane, theoretical and experimental studies on near-field multiple traps of paraxial acoustic vortices (AVs) with a strengthened acoustic gradient force (AGF) generated by a sector transducer array were conducted. By applying the integration of point source radiation, numerical simulations for the acoustic fields generated by the sector transducer array were conducted and compared with those produced by the circular transducer array. It was proved that strengthened AGFs of near-field multiple AVs with higher peak pressures and smaller vortex radii could be produced by the sector transducer array with a small topological charge. The axial distributions of the equivalent potential gradient indicated that the AGFs of paraxial AVs in the near field were much higher than those in the far field, and the distances at the near-field vortex antinodes were also proved to be the ideal trapping positions with relatively higher AGFs. With the established 8-channel AV generation system, theoretical studies were also verified by the experimental measurements of pressure and phase for AVs with various topological charges. The formation of near-field multiple paraxial AVs was verified by the cross-sectional circular pressure distributions with perfect phase spirals around central pressure nulls, and was also proved by the vortex nodes and antinodes along the center axis. The favorable results demonstrated the feasibility of generating near-field multiple traps of paraxial AVs with strengthened AGF using the sector transducer array, and suggested the potential applications of close-range particle trapping in biomedical engineering.

  13. Geochemistry and mercury contamination in receiving environments of artisanal mining wastes and identified concerns for food safety

    International Nuclear Information System (INIS)

    Reichelt-Brushett, Amanda J.; Stone, Jane; Howe, Pelli; Thomas, Bernard; Clark, Malcolm; Male, Yusthinus; Nanlohy, Albert; Butcher, Paul

    2017-01-01

    Artisanal small-scale gold mining (ASGM) using mercury (Hg) amalgamation has been occurring on Buru Island, Indonesia since early 2012, and has caused rapid accumulation of high Hg concentrations in river, estuary and marine sediments. In this study, sediment samples were collected from several sites downstream of the Mount Botak ASGM site, as well as in the vicinity of the more recently established site at Gogrea where no sampling had previously been completed. All sediment samples had total Hg (THg) concentrations exceeding Indonesian sediment quality guidelines and were up to 82 times this limit at one estuary site. The geochemistry of sediments in receiving environments indicates the potential for Hg-methylation to form highly bioavailable Hg species. To assess the current contamination threat from consumption of local seafood, samples of fish, molluscs and crustaceans were collected from the Namlea fish market and analysed for THg concentrations. The majority of edible tissue samples had elevated THg concentrations, which raises concerns for food safety. This study shows that river, estuary and marine ecosystems downstream of ASGM operations on Buru Island are exposed to dangerously high Hg concentrations, which are impacting aquatic food chains, and fisheries resources. Considering the high dietary dependence on marine protein in the associated community and across the Mollucas Province, and the short time period since ASGM operations commenced in this region, the results warrant urgent further investigation, risk mitigation, and community education. - Highlights: • Mercury contamination of sediments and seafood due to artisanal gold mining. • Considerable risks to human and ecosystem health are identified. • Results emphasise the urgent need for risk mitigation and community education.

  14. Geochemistry and mercury contamination in receiving environments of artisanal mining wastes and identified concerns for food safety

    Energy Technology Data Exchange (ETDEWEB)

    Reichelt-Brushett, Amanda J., E-mail: amanda.reichelt-brushett@scu.edu.au [Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW (Australia); School of Environment, Science and Engineering Southern Cross University, PO Box 157, Lismore, NSW (Australia); Stone, Jane [School of Environment, Science and Engineering Southern Cross University, PO Box 157, Lismore, NSW (Australia); Howe, Pelli [Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW (Australia); School of Environment, Science and Engineering Southern Cross University, PO Box 157, Lismore, NSW (Australia); Thomas, Bernard [School of Environment, Science and Engineering Southern Cross University, PO Box 157, Lismore, NSW (Australia); Clark, Malcolm [Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW (Australia); School of Environment, Science and Engineering Southern Cross University, PO Box 157, Lismore, NSW (Australia); Male, Yusthinus [Department of Chemistry, Faculty of Mathematics and Natural Science, Pattimura University, Ambon (Indonesia); Nanlohy, Albert [Department of Fisheries and Marine Science, Pattimura University, Ambon (Indonesia); Butcher, Paul [School of Environment, Science and Engineering Southern Cross University, PO Box 157, Lismore, NSW (Australia); NSW Department of Primary Industries, National Marine Science Centre, PO Box 4321, Coffs Harbour, NSW (Australia)

    2017-01-15

    Artisanal small-scale gold mining (ASGM) using mercury (Hg) amalgamation has been occurring on Buru Island, Indonesia since early 2012, and has caused rapid accumulation of high Hg concentrations in river, estuary and marine sediments. In this study, sediment samples were collected from several sites downstream of the Mount Botak ASGM site, as well as in the vicinity of the more recently established site at Gogrea where no sampling had previously been completed. All sediment samples had total Hg (THg) concentrations exceeding Indonesian sediment quality guidelines and were up to 82 times this limit at one estuary site. The geochemistry of sediments in receiving environments indicates the potential for Hg-methylation to form highly bioavailable Hg species. To assess the current contamination threat from consumption of local seafood, samples of fish, molluscs and crustaceans were collected from the Namlea fish market and analysed for THg concentrations. The majority of edible tissue samples had elevated THg concentrations, which raises concerns for food safety. This study shows that river, estuary and marine ecosystems downstream of ASGM operations on Buru Island are exposed to dangerously high Hg concentrations, which are impacting aquatic food chains, and fisheries resources. Considering the high dietary dependence on marine protein in the associated community and across the Mollucas Province, and the short time period since ASGM operations commenced in this region, the results warrant urgent further investigation, risk mitigation, and community education. - Highlights: • Mercury contamination of sediments and seafood due to artisanal gold mining. • Considerable risks to human and ecosystem health are identified. • Results emphasise the urgent need for risk mitigation and community education.

  15. Minimal BRDF Sampling for Two-Shot Near-Field Reflectance Acquisition

    DEFF Research Database (Denmark)

    Xu, Zexiang; Nielsen, Jannik Boll; Yu, Jiyang

    2016-01-01

    We develop a method to acquire the BRDF of a homogeneous flat sample from only two images, taken by a near-field perspective camera, and lit by a directional light source. Our method uses the MERL BRDF database to determine the optimal set of lightview pairs for data-driven reflectance acquisition...

  16. The analysis and design of urban near-home environments according to psycho-social needs and behavior of human beings

    OpenAIRE

    Serpil, Burçak

    1996-01-01

    Ankara : Department of Interior Architecture and Environmental Design and the Institute of Fine Arts of Bilkent University, 1996. Thesis (Master's) -- Bilkent University, 1996. Includes bibliographical references leaves 129-132. In this study, the design of urban near-home environments is examined considering the social and psychological needs of human beings as well as human spatial behavior. After an introduction to the concepts such as environment, near-home environments, human-e...

  17. Near field communication (NFC) model for arduino uno based security systems office system

    Science.gov (United States)

    Chairunnas, A.; Abdurrasyid, I.

    2018-03-01

    Currently, many offices or companies that start growing rapidly in a company or office should have a very limited room to enter only people entitled to enter the room and use the facilities contained in it, for example, Files in it must have many files and documents very important because to reduce the abuse of files and irresponsible person. Because it will be made room door security system by using Near Field Communication on android smartphone. Software used is Arduino IDE. The tools used in this system are Arduino Uno R3, NFC shield, pear sensor, bell, led, servo, 16 × 2 LCD, and Near Field Communication (NFC) in android smartphone. This system runs based on 2 inputs of a new technology that is Near Field Communication (NFC) in android smartphone. And also use pear sensor to detect unauthorized person entering the room. If the correct password is entered then the door will open and the pear sensor will light off if wrong then the bell will light up.

  18. An overview on geochemistry of Proterozoic massif-type ...

    Indian Academy of Sciences (India)

    A critical study of 311 published WR chemical analyses, isotopic and mineral chemistry of ... Keywords. Massif anorthosite complexes; overview; geochemistry; high-Al gabbro. J. Earth ...... (123–2920 ppm) unlike the experimental results of.

  19. Sub-wavelength imaging by depolarization in a reflection near-field optical microscope using an uncoated fiber probe

    DEFF Research Database (Denmark)

    Madsen, Steen; Bozhevolnyi, Sergey I.; Hvam, Jørn Märcher

    1998-01-01

    We present a reflection scanning near-field optical microscope utilizing counter-directional light propagation in an uncoated fiber probe, cross-polarized detection and shear-force feedback. Topographical and near-field optical imaging with a scanning speed of up to 10 mu m/s and a lateral...... resolution better than 40 nm are demonstrated with a latex projection test sample. Determination of the optical resolution as well as correlation between topographical and near-field optical images are discussed. (C) 1998 Elsevier Science B.V....

  20. Sedimentary basin geochemistry and fluid/rock interactions workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-12-31

    Fundamental research related to organic geochemistry, fluid-rock interactions, and the processes by which fluids migrate through basins has long been a part of the U.S. Department of Energy Geosciences program. Objectives of this program were to emphasize those principles and processes which would be applicable to a wide range of problems associated with petroleum discovery, occurrence and extraction, waste disposal of all kinds, and environmental management. To gain a better understanding of the progress being made in understanding basinal fluids, their geochemistry and movement, and related research, and to enhance communication and interaction between principal investigators and DOE and other Federal program managers interested in this topic, this workshop was organized by the School of Geology and Geophysics and held in Norman, Oklahoma in November, 1991.

  1. Relevance of near-Earth magnetic field modeling in deriving SEP properties using ground-based data

    Science.gov (United States)

    Kanellakopoulos, Anastasios; Plainaki, Christina; Mavromichalaki, Helen; Laurenza, Monica; Gerontidou, Maria; Storini, Marisa; Andriopoulou, Maria

    2014-05-01

    Ground Level Enhancements (GLEs) are short-term increases observed in cosmic ray intensity records of ground-based particle detectors such as neutron monitors (NMs) or muon detectors; they are related to the arrival of solar relativistic particles in the terrestrial environment. Hence, GLE events are related to the most energetic class of solar energetic particle (SEP) events. In this work we investigate how the use of different magnetospheric field models can influence the derivation of the relativistic SEP properties when modeling GLE events. As a case study, we examine the event of 2012 May 17 (also known as GLE71), registered by ground-based NMs. We apply the Tsyganenko 89 and the Tsyganenko 96 models in order to calculate the trajectories of the arriving SEPs in the near-Earth environment. We show that the intersection of the SEP trajectories with the atmospheric layer at ~20 km from the Earth's surface (i.e., where the flux of the generated secondary particles is maximum), forms for each ground-based neutron monitor a specified viewing region that is dependent on the magnetospheric field configuration. Then, we apply the Neutron Monitor Based Anisotropic GLE Pure Power Law (NMBANGLE PPOLA) model (Plainaki et al. 2010, Solar Phys, 264, 239), in order to derive the spectral properties of the related SEP event and the spatial distributions of the SEP fluxes impacting the Earth's atmosphere. We examine the dependence of the results on the used magnetic field models and evaluate their range of validity. Finally we discuss information derived by modeling the SEP spectrum in the frame of particle acceleration scenarios.

  2. The Swedish final repository for reactor waste (SFR). A summary of the SFR project with special emphasis on the near-field assessments

    International Nuclear Information System (INIS)

    Carlsson, J.

    1988-01-01

    The first phase of the final repository for reactor waste (SFR) is scheduled for operation in April 1988. The construction work is finished and preoperational tests are in progress. Impact on the environment from SFR is analysed in a final safety report. This paper gives a summary of the design and performance of SFR. Assessments, made for the analysises of the long term safety, are given with special emphasis on the near-field. As a conclusion from the analysises, the dose commitment to the most affected individual during the post-closure period, has proved to constitute only an insignificant contribution to the natural radioactive environment of the area

  3. Near-field terahertz imaging of ferroelectric domains in barium titanate

    Czech Academy of Sciences Publication Activity Database

    Berta, Milan; Kadlec, Filip

    2010-01-01

    Roč. 83, 10-11 (2010), 985-993 ISSN 0141-1594 R&D Projects: GA MŠk LC512 Institutional research plan: CEZ:AV0Z10100520 Keywords : singular value decomposition * domain structure imaging * near-field terahertz microscopy * subwavelength resolution Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.006, year: 2010

  4. Geochemistry of zinc in the sediments of the western continental shelf and slope of India

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, P.S.N.; Paropkari, A.L.; Rao, Ch.M.

    The bulk geochemistry of zinc in the sediments of the western continental shelf and slope of India and also the partition geochemistry of the sediments of the shelf and slope regions between Ratnagiri and Mangalore have been studied. The studies...

  5. Epidermal electronics with advanced capabilities in near-field communication.

    Science.gov (United States)

    Kim, Jeonghyun; Banks, Anthony; Cheng, Huanyu; Xie, Zhaoqian; Xu, Sheng; Jang, Kyung-In; Lee, Jung Woo; Liu, Zhuangjian; Gutruf, Philipp; Huang, Xian; Wei, Pinghung; Liu, Fei; Li, Kan; Dalal, Mitul; Ghaffari, Roozbeh; Feng, Xue; Huang, Yonggang; Gupta, Sanjay; Paik, Ungyu; Rogers, John A

    2015-02-25

    Epidermal electronics with advanced capabilities in near field communications (NFC) are presented. The systems include stretchable coils and thinned NFC chips on thin, low modulus stretchable adhesives, to allow seamless, conformal contact with the skin and simultaneous capabilities for wireless interfaces to any standard, NFC-enabled smartphone, even under extreme deformation and after/during normal daily activities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Use of Near Field Communication in emergency Rescue situations

    DEFF Research Database (Denmark)

    Kramp, Gunnar

    2006-01-01

    Near Field Communication (NFC) where the placement of two devices in close proximity of each other makes it possible for two devices to exhange and share information, opens up for a variety of transparent and intuitive interaction possibilities. However, as we have identified in the palcom project...... [1], instant and appropriate feedback regarding state of the connection and identification of which devices are connected to each other, is crucial for use....

  7. Near-Field Microwave Magnetic Nanoscopy of Superconducting Radio Frequency Cavity Materials

    OpenAIRE

    Tai, Tamin; Ghamsari, Behnood G.; Bieler, Thomas R.; Tan, Teng; Xi, X. X.; Anlage, Steven M.

    2013-01-01

    A localized measurement of the RF critical field on superconducting radio frequency (SRF) cavity materials is a key step to identify specific defects that produce quenches of SRF cavities. Two new measurements are performed to demonstrate these capabilities with a novel near-field scanning probe microwave microscope. The first is a third harmonic nonlinear measurement on a high Residual- Resistance-Ratio bulk Nb sample showing strong localized nonlinear response for the first time, with surfa...

  8. Deep underground disposal of radioactive wastes: Near field effects

    International Nuclear Information System (INIS)

    1985-01-01

    This report reviews the important near-field effects of the disposal of wastes in deep rock formations. The basic characteristics of waste form, container and package, buffer and backfill materials and potential host-rock types are discussed from the perspective of the performance requirements of the total repository system. Effects of waste emplacement on the separate system components and on the system as a whole are discussed. The effects include interactions between groundwater and brines and the other system components, thermal and thermo-mechanical effects, and chemical and geochemical reactions. Special consideration is given to the radiation field that exists in proximity to the waste containers and also to the coupled effects of different phenomena

  9. Large-scale, near-Earth, magnetic fields from external sources and the corresponding induced internal field

    Science.gov (United States)

    Langel, R. A.; Estes, R. H.

    1983-01-01

    Data from MAGSAT analyzed as a function of the Dst index to determine the first degree/order spherical harmonic description of the near-Earth external field and its corresponding induced field. The analysis was done separately for data from dawn and dusk. The MAGSAT data was compared with POGO data. A local time variation of the external field persists even during very quiet magnetic conditions; both a diurnal and 8-hour period are present. A crude estimate of Sq current in the 45 deg geomagnetic latitude range is obtained for 1966 to 1970. The current strength, located in the ionosphere and induced in the Earth, is typical of earlier determinations from surface data, although its maximum is displaced in local time from previous results.

  10. Cold aqueous planetary geochemistry with FREZCHEM from modeling to the search for life at the limits

    CERN Document Server

    Marion, Giles M

    2007-01-01

    This book explicitly investigates issues of astrobiological relevance in the context of cold aqueous planetary geochemistry. At the core of the technical chapters is the FREZCHEM model, initially developed over many years by one of the authors to quantify aqueous electrolyte properties and chemical thermodynamics at subzero temperatures. FREZCHEM, of general relevance to biogeochemists and geochemical modelers, cold planetary scientists, physicochemists and chemical engineers, is subsequently applied to the exploration of biogeochemical applications to solar systems bodies in general, and to speculations about the limits for life in cold environments in particular.

  11. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    International Nuclear Information System (INIS)

    R. Jarek

    2005-01-01

    The purpose of this model report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The resulting seepage evaporation and gas abstraction models are used in the total system performance assessment for the license application (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2005 [DIRS 173782], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports. To be consistent with other project documents that address features, events, and processes (FEPs), Table 6.14.1 of the current report includes updates to FEP numbers and FEP subjects for two FEPs identified in the technical work plan (TWP) governing this report (BSC 2005 [DIRS 173782]). FEP 2.1.09.06.0A (Reduction-oxidation potential in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.06.0B (Reduction-oxidation potential in Drifts; see Table 6.14-1). FEP 2.1.09.07.0A (Reaction kinetics in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.07.0B (Reaction kinetics in Drifts; see Table 6.14-1). These deviations from the TWP are justified because they improve integration with FEPs documents. The updates

  12. Energy modulation of nonrelativistic electrons in an optical near field on a metal microslit

    OpenAIRE

    R., Ishikawa; Jongsuck, Bae; K., Mizuno

    2001-01-01

    Energy modulation of nonrelativistic electrons with a laser beam using a metal microslit as an interaction circuit has been investigated. An optical near field is induced in the proximity of the microslit by illumination of the laser beam. The electrons passing close to the slit are accelerated or decelerated by an evanescent wave contained in the near field whose phase velocity is equal to the velocity of the electrons. The electron-evanescent wave interaction in the microslit has been analy...

  13. Near-field scanning optical microscopy using polymethylmethacrylate optical fiber probes

    International Nuclear Information System (INIS)

    Chibani, H.; Dukenbayev, K.; Mensi, M.; Sekatskii, S.K.; Dietler, G.

    2010-01-01

    We report the first use of polymethylmethacrylate (PMMA) optical fiber-made probes for scanning near-field optical microscopy (SNOM). The sharp tips were prepared by chemical etching of the fibers in ethyl acetate, and the probes were prepared by proper gluing of sharpened fibers onto the tuning fork in the conditions of the double resonance (working frequency of a tuning fork coincides with the resonance frequency of dithering of the free-standing part of the fiber) reported earlier for the case of glass fibers. Quality factors of the probes in the range 2000-6000 were obtained, which enables the realization of an excellent topographical resolution including state-of-art imaging of single DNA molecules. Near-field optical performance of the microscope is illustrated by the Photon Scanning Tunneling Microscope images of fluorescent beads with a diameter of 100 nm. The preparation of these plastic fiber probes proved to be easy, needs no hazardous material and/or procedures, and typical lifetime of a probe essentially exceeds that characteristic for the glass fiber probe.

  14. Apertureless near-field terahertz imaging using the self-mixing effect in a quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Dean, Paul, E-mail: p.dean@leeds.ac.uk; Keeley, James; Kundu, Iman; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Mitrofanov, Oleg [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2016-02-29

    We report two-dimensional apertureless near-field terahertz (THz) imaging using a quantum cascade laser (QCL) source and a scattering probe. A near-field enhancement of the scattered field amplitude is observed for small tip-sample separations, allowing image resolutions of ∼1 μm (∼λ/100) and ∼7 μm to be achieved along orthogonal directions on the sample surface. This represents the highest resolution demonstrated to date with a THz QCL. By employing a detection scheme based on self-mixing interferometry, our approach offers experimental simplicity by removing the need for an external detector and also provides sensitivity to the phase of the reinjected field.

  15. Near-field microwave magnetic nanoscopy of superconducting radio frequency cavity materials

    Science.gov (United States)

    Tai, Tamin; Ghamsari, Behnood G.; Bieler, Thomas R.; Tan, Teng; Xi, X. X.; Anlage, Steven M.

    2014-06-01

    A localized measurement of the RF critical field on superconducting radio frequency (SRF) cavity materials is a key step to identify specific defects that produce quenches of SRF cavities. Two measurements are performed to demonstrate these capabilities with a near-field scanning probe microwave microscope. The first is a third harmonic nonlinear measurement on a high Residual-Resistance-Ratio bulk Nb sample showing strong localized nonlinear response, with surface RF magnetic field Bsurface˜102 mT. The second is a raster scanned harmonic response image on a MgB2 thin film demonstrating a uniform nonlinear response over large areas.

  16. Near field acoustic holography with microphones mounted on a rigid sphere

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Moreno, Guillermo; Fernandez Grande, Efren

    2008-01-01

    Spherical near field acoustic holography (spherical NAH) is a technique that makes it pos-sible to reconstruct the sound field inside and just outside an acoustically transparent spherical surface on which the sound pressure is measured with an array of microphones with negligible scattering...... is only valid if it can be assumed that the sphere has a negligible in-fluence on the incident sound field, and this is not necessarily a good assumption when the sphere is very close to a radiating surface. This paper describes the modified spherical NAH theory and examines the matter through simulations...

  17. Spherical near field acoustic holography with microphones on a rigid sphere

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Hald, Jørgen; Fernandez Grande, Efren

    2008-01-01

    Spherical near field acoustic holography (SNAH) is a recently developed technique that makes it possible to reconstruct the sound field inside and just outside an acoustically transparent spherical surface on which the sound pressure is measured with an array of microphones with negligible...... with an array of microphones flush-mounted on a rigid sphere. However, this approach is only valid if it can be assumed that the sphere has a negligible influence on the incident sound field, in other words if multiple scattering can be ignored, and this is not necessarily a good assumption when the sphere...

  18. 3D Global Coronal Density Structure and Associated Magnetic Field near Solar Maximum

    Energy Technology Data Exchange (ETDEWEB)

    Kramar, Maxim [Physics Department, The Catholic University of America, Washington, DC (United States); Airapetian, Vladimir [Department of Physics and Astronomy, George Mason University, Fairfax, VA (United States); NASA/Goddard Space Flight Center, Code 671, Greenbelt, MD (United States); Lin, Haosheng, E-mail: vladimir.airapetian@nasa.gov [College of Natural Sciences, Institute for Astronomy, University of Hawaii at Manoa, Pukalani, HI (United States)

    2016-08-09

    Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal dynamic phenomena at all scales. We employ STEREO/COR1 data obtained near maximum of solar activity in December 2012 (Carrington rotation, CR 2131) to retrieve and analyze the three-dimensional (3D) coronal electron density in the range of heights from 1.5 to 4 R{sub ⊙} using a tomography method and qualitatively deduce structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in 195 Å band obtained by tomography for the same CR period. We find that the magnetic field configuration during CR 2131 has a tendency to become radially open at heliocentric distances below ~2.5 R{sub ⊙}. We compared the reconstructed 3D coronal structures over the CR near the solar maximum to the one at deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal field models and test the accuracy of the magnetic field approximations for coronal modeling.

  19. 3D Global Coronal Density Structure and Associated Magnetic Field near Solar Maximum

    Directory of Open Access Journals (Sweden)

    Maxim Kramar

    2016-08-01

    Full Text Available Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal dynamic phenomena at all scales. We employ STEREO/COR1 data obtained near maximum of solar activity in December 2012 (Carrington rotation, CR 2131 to retrieve and analyze the three-dimensional (3D coronal electron density in the range of heights from $1.5$ to $4 R_odot$ using a tomography method and qualitatively deduce structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in 195 AA band obtained by tomography for the same CR period. We find that the magnetic field configuration during CR 2131 has a tendency to become radially open at heliocentric distances below $sim 2.5 R_odot$. We compared the reconstructed 3D coronal structures over the CR near the solar maximum to the one at deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal field models and test the accuracy of the magnetic field approximations for coronal modeling.

  20. Mixed Far-Field and Near-Field Source Localization Algorithm via Sparse Subarrays

    Directory of Open Access Journals (Sweden)

    Jiaqi Song

    2018-01-01

    Full Text Available Based on a dual-size shift invariance sparse linear array, this paper presents a novel algorithm for the localization of mixed far-field and near-field sources. First, by constructing a cumulant matrix with only direction-of-arrival (DOA information, the proposed algorithm decouples the DOA estimation from the range estimation. The cumulant-domain quarter-wavelength invariance yields unambiguous estimates of DOAs, which are then used as coarse references to disambiguate the phase ambiguities in fine estimates induced from the larger spatial invariance. Then, based on the estimated DOAs, another cumulant matrix is derived and decoupled to generate unambiguous and cyclically ambiguous estimates of range parameter. According to the coarse range estimation, the types of sources can be identified and the unambiguous fine range estimates of NF sources are obtained after disambiguation. Compared with some existing algorithms, the proposed algorithm enjoys extended array aperture and higher estimation accuracy. Simulation results are given to validate the performance of the proposed algorithm.

  1. Plasma Interaction and Energetic Particle Dynamics near Callisto

    Science.gov (United States)

    Liuzzo, L.; Simon, S.; Feyerabend, M.; Motschmann, U. M.

    2017-12-01

    Callisto's magnetic environment is characterized by a complex admixture of induction signals from its conducting subsurface ocean, the interaction of corotating Jovian magnetospheric plasma with the moon's ionosphere and induced dipole, and the non-linear coupling between the effects. In contrast to other Galilean moons, ion gyroradii near Callisto are comparable to its size, requiring a kinetic treatment of the interaction region near the moon. Thus, we apply the hybrid simulation code AIKEF to constrain the competing effects of plasma interaction and induction. We determine their influence on the magnetic field signatures measured by Galileo during various Callisto flybys. We use the magnetic field calculated by the model to investigate energetic particle dynamics and their effect on Callisto's environment. From this, we provide a map of global energetic particle precipitation onto Callisto's surface, which may contribute to the generation of its atmosphere.

  2. Near field imaging of transient collisional excitation x-ray laser

    International Nuclear Information System (INIS)

    Tanaka, Momoko; Kado, Masataka; Hasegawa, Noboru; Kawachi, Tetsuya; Sukegawa, Kouta; Lu, Peixiang; Nagashima, Akira; Kato, Yoshiaki

    2001-01-01

    We observed the spatial profile of the transient collisional excitation Ni-like Ag laser (λ=13.9 nm) for various plasma lengths using the near field imaging method. The gain coefficient of the x-ray laser was estimated as 24 cm -1 . The gain region was a 50 μm crescent shape and included localized high gain areas. (author)

  3. Near-field imaging of interference pattern of counterpropagating evanescent waves

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Bozhevolnaya, Elena A.

    1999-01-01

    It is generally accepted that measurement of of the contrast of the intensity interference pattern formed by two counterpropagating evanescent waves can be used to characterize the resolving power of a collection near-field microscope. We argue that, if the light collected by a fiber probe propag...... be equal to the contrast of the interference pattern....

  4. Geochemistry and petrogenesis of Proterozoic granitic rocks from ...

    Indian Academy of Sciences (India)

    Geochemistry and petrogenesis of Proterozoic granitic ... This study presents the geochemical characteristics of granitic rocks located on the northern ... Frost and Frost 2013). ...... King P L, White A J R, Chappell B W and Allen C M 1997.

  5. Near-field enhanced femtosecond laser nano-drilling of glass substrate

    International Nuclear Information System (INIS)

    Zhou, Y.; Hong, M.H.; Fuh, J.Y.H.; Lu, L.; Lukyanchuk, B.S.; Wang, Z.B.

    2008-01-01

    Particle mask assisted near-field enhanced femtosecond laser nano-drilling of transparent glass substrate was demonstrated in this paper. A particle mask was fabricated by self-assembly of spherical 1 μm silica particles on the substrate surface. Then the samples were exposed to femtosecond laser (800 nm, 100 fs) and characterized by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The nano-hole array was found on the glass surface. The hole sizes were measured from 200 to 300 nm with an average depth of 150 nm and increased with laser fluence. Non-linear triple-photon absorption and near-field enhancement were the main mechanisms of the nano-feature formation. Calculations based on Mie theory shows an agreement with experiment results. More debris, however, was found at high laser fluence. This can be attributed to the explosion of silica particles because the focusing point is inside the 1 μm particle. The simulation predicts that the focusing point will move outside the particle if the particle size increases. The experiment performed under 6.84 μm silica particles verified that no debris was formed. And for all the samples, no cracks were found on the substrate surface because of ultra-short pulse width of femtosecond laser. This method has potential applications in nano-patterning of transparent glass substrate for nano-structure device fabrication

  6. Patch near-field acoustic holography: The influence of acoustic contributions from outside the source

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Zhang, Yong-Bin

    2009-01-01

    It is a requirement of conventional Near-field Acoustic Holography that the measurement area covers the entire surface of the source. In the case of Patch Near-field Acoustic Holography (patch NAH), the measurement area can be reduced to cover only a specific area of the source which...... is of particular interest (known as the “patch” or “source patch”). The area of the source beyond this patch is not of interest in the analysis. However, its acoustic output may nevertheless contribute to the total sound field in the measurement plane, and influence the reconstruction of the field close...... to the patch. The purpose of this paper is to investigate how the acoustic radiation from outside the patch area influences the reconstruction of the sound field close to the source. The reconstruction is based on simulated measurements of sound pressure and particle velocity. The methods used in this paper...

  7. Development of Spherical Near Field Model for Geological Radioactive Waste Repository

    International Nuclear Information System (INIS)

    Kim, S. Y.; Lee, K. J.; Chang, S. H.; Lee, K. J.; Chang, S. H.

    2012-01-01

    Modeling for geological radioactive waste repository can be divided into 3 parts. They are near field modeling related to engineered barrier, far field modeling related to natural barrier and biosphere modeling. In order to make the general application for safety assessment of geological waste repository, spherical geometry near field model has been developed. This model can be used quite extensively when users calculate equivalent spherical geometry for specific engineered barrier like equivalent waste radius, equivalent barrier radius and etc. Only diffusion was considered for general purpose but advection part can be updated. Goldsim and Goldsim Radionuclide Transport (RT) module were chosen and used as developing tool for the flexible modeling. Developer can freely make their own model with developer friendly graphic interface by using Goldsim. Furthermore, model with user friendly graphic interface can be developed by using Goldsim Dashboard Authoring module. The model has been validated by comparing the result with that of another model, inserting similar inputs and conditions. The model has been proved to be reasonably operating from the comparison result by validation process. Cylindrical model can be developed as a further work based on the knowledge and experience from this research

  8. Development of Spherical Near Field Model for Geological Radioactive Waste Repository

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. Y.; Lee, K. J.; Chang, S. H. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Lee, K. J.; Chang, S. H. [Khalifa Univ. of Science/Technology and Research, Abu Dhabi (United Arab Emirates)

    2012-03-15

    Modeling for geological radioactive waste repository can be divided into 3 parts. They are near field modeling related to engineered barrier, far field modeling related to natural barrier and biosphere modeling. In order to make the general application for safety assessment of geological waste repository, spherical geometry near field model has been developed. This model can be used quite extensively when users calculate equivalent spherical geometry for specific engineered barrier like equivalent waste radius, equivalent barrier radius and etc. Only diffusion was considered for general purpose but advection part can be updated. Goldsim and Goldsim Radionuclide Transport (RT) module were chosen and used as developing tool for the flexible modeling. Developer can freely make their own model with developer friendly graphic interface by using Goldsim. Furthermore, model with user friendly graphic interface can be developed by using Goldsim Dashboard Authoring module. The model has been validated by comparing the result with that of another model, inserting similar inputs and conditions. The model has been proved to be reasonably operating from the comparison result by validation process. Cylindrical model can be developed as a further work based on the knowledge and experience from this research.

  9. Simulated near-field mapping of ripple pattern supported metal nanoparticles arrays for SERS optimization

    Science.gov (United States)

    Arya, Mahima; Bhatnagar, Mukul; Ranjan, Mukesh; Mukherjee, Subroto; Nath, Rabinder; Mitra, Anirban

    2017-11-01

    An analytical model has been developed using a modified Yamaguchi model along with the wavelength dependent plasmon line-width correction. The model has been used to calculate the near-field response of random nanoparticles on the plane surface, elongated and spherical silver nanoparticle arrays supported on ion beam produced ripple patterned templates. The calculated near-field mapping for elongated nanoparticles arrays on the ripple patterned surface shows maximum number of hot-spots with a higher near-field enhancement (NFE) as compared to the spherical nanoparticle arrays and randomly distributed nanoparticles on the plane surface. The results from the simulations show a similar trend for the NFE when compared to the far field reflection spectra. The nature of the wavelength dependent NFE is also found to be in agreement with the observed experimental results from surface enhanced Raman spectroscopy (SERS). The calculated and the measured optical response unambiguously reveal the importance of interparticle gap and ordering, where a high intensity Raman signal is obtained for ordered elongated nanoparticles arrays case as against non-ordered and the aligned configuration of spherical nanoparticles on the rippled surface.

  10. Near-field photochemical and radiation-induced chemical fabrication of nanopatterns of a self-assembled silane monolayer

    Directory of Open Access Journals (Sweden)

    Ulrich C. Fischer

    2014-09-01

    Full Text Available A general concept for parallel near-field photochemical and radiation-induced chemical processes for the fabrication of nanopatterns of a self-assembled monolayer (SAM of (3-aminopropyltriethoxysilane (APTES is explored with three different processes: 1 a near-field photochemical process by photochemical bleaching of a monomolecular layer of dye molecules chemically bound to an APTES SAM, 2 a chemical process induced by oxygen plasma etching as well as 3 a combined near-field UV-photochemical and ozone-induced chemical process, which is applied directly to an APTES SAM. All approaches employ a sandwich configuration of the surface-supported SAM, and a lithographic mask in form of gold nanostructures fabricated through colloidal sphere lithography (CL, which is either exposed to visible light, oxygen plasma or an UV–ozone atmosphere. The gold mask has the function to inhibit the photochemical reactions by highly localized near-field interactions between metal mask and SAM and to inhibit the radiation-induced chemical reactions by casting a highly localized shadow. The removal of the gold mask reveals the SAM nanopattern.

  11. Conference Paper NFO-7:7th International Conference on Near-Field Optics and Related Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Novotny, Lukas [Univ. of Rochester, NY (United States)

    2004-10-18

    The seventh conference in the NFO conference series, held here in Rochester, provided to be the principal forum for advances in sub-wavelength optics, near-field optical microscopy, local field enhancement, instrumental developments and the ever-increasing range of applications. This conference brought together the diverse scientific communities working on the theory and application of near-field optics (NFO) and related techniques.

  12. Geochemistry and Petrogenesis of Biabanak–Bafq Mafic Mgmatism ...

    Indian Academy of Sciences (India)

    59

    13185-1494. Email: m_poshtkoohi@yahoo.com; Mobile No: +98 912 209 39 73 ...... petrologie et tectonique du precambrien et de sa couverture, Ph.D. thesis, universite ..... Applications of the 190Pt–186OS isotope system to geochemistry and.

  13. Broadband X-ray Imaging in the Near-Field Region of an Airblast Atomizer

    Science.gov (United States)

    Li, Danyu; Bothell, Julie; Morgan, Timothy; Heindel, Theodore

    2017-11-01

    The atomization process has a close connection to the efficiency of many spray applications. Examples include improved fuel atomization increasing the combustion efficiency of aircraft engines, or controlled droplet size and spray angle enhancing the quality and speed of the painting process. Therefore, it is vital to understand the physics of the atomization process, but the near-field region is typically optically dense and difficult to probe with laser-based or intrusive measurement techniques. In this project, broadband X-ray radiography and X-ray computed tomography (CT) imaging were performed in the near-field region of a canonical coaxial airblast atomizer. The X-ray absorption rate was enhanced by adding 20% by weight of Potassium Iodide to the liquid phase to increase image contrast. The radiographs provided an estimate of the liquid effective mean path length and spray angle at the nozzle exit for different flow conditions. The reconstructed CT images provided a 3D map of the time-average liquid spray distribution. X-ray imaging was used to quantify the changes in the near-field spray characteristics for various coaxial airblast atomizer flow conditions. Office of Naval Research.

  14. FDTD simulations of near-field mediated semiconductor molecular optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dai; Sakrow, Marcus; Mihaljevic, Josip; Meixner, Alfred J. [Institute of Physical and Theoretical Chemistry, University Tuebingen, Auf der Morgenstelle 8, Tuebingen (Germany)

    2010-07-01

    The optical properties of molecules can be dramatically altered when they are in a close proximity of an excited metal antenna. In order to get insight into how the antenna generated near-field influences the optical properties of low quantum yield molecules, we carried out FDTD simulations of a sharp laser-illuminated Au tip approaching to a semiconductor thin film. The time-averaged field distribution between the semiconductor thin film and the tip antenna is calculated regarding to different distances. Our calculation demonstrates that the coupling between the localized plasmon at the tip apex and semiconductor polariton can be achieved building up a distance-dependent high field enhancement. Our experimental results show that such a high field strength enhances not only the excitation process by a factor of 104, but alters the radiative: non-radiative decay rate giving approx. 15 times stronger photoluminescence emission.

  15. A near-field scanning microwave microscope based on a superconducting resonator for low power measurements.

    Science.gov (United States)

    de Graaf, S E; Danilov, A V; Adamyan, A; Kubatkin, S E

    2013-02-01

    We report on the design and performance of a cryogenic (300 mK) near-field scanning microwave microscope. It uses a microwave resonator as the near-field sensor, operating at a frequency of 6 GHz and microwave probing amplitudes down to 100 μV, approaching low enough photon population (N ∼ 1000) of the resonator such that coherent quantum manipulation becomes feasible. The resonator is made out of a miniaturized distributed fractal superconducting circuit that is integrated with the probing tip, micromachined to be compact enough such that it can be mounted directly on a quartz tuning-fork, and used for parallel operation as an atomic force microscope (AFM). The resonator is magnetically coupled to a transmission line for readout, and to achieve enhanced sensitivity we employ a Pound-Drever-Hall measurement scheme to lock to the resonance frequency. We achieve a well localized near-field around the tip such that the microwave resolution is comparable to the AFM resolution, and a capacitive sensitivity down to 6.4 × 10(-20) F/Hz, limited by mechanical noise. We believe that the results presented here are a significant step towards probing quantum systems at the nanoscale using near-field scanning microwave microscopy.

  16. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Stephen J.; Ni, Guangjian [Institute of Sound and Vibration Research, University of Southampton, Southampton (United Kingdom)

    2015-12-31

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a “coupling mass” effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  17. System studies in PA: Development of process influence diagram (PID) for SFR-1 repository near-field + far-field

    International Nuclear Information System (INIS)

    Stenhouse, M.J.; Miller, W.M.; Chapman, N.A.

    2001-05-01

    Scenario development is a key component of the performance assessment (PA) process for radioactive waste disposal, the primary objective being to ensure that all relevant factors associated with the future evolution of the repository system are properly considered in PA. As part of scenario development, a list of features, events and processes (FEPs) are identified and assembled, representing the Process System, with interactions/influences between FEPs incorporated in a Process Influence Diagram (PID). This report documents the technical work conducted between 1997 and the end of 1999 under the Systems Studies Project. The overall objective of this project has been the construction of a PID for the SFR-1 repository (final repository for reactor waste), this PID being the first stage in the identification of scenarios to describe future evolution of this repository. The PIDs discussed in this report have been created using two software applications: existing commercial software (Business Modeller, Infotool AB. Stockholm, Sweden) and, more recently, a newly developed software tool SPARTA (Enviros QuantiSci, Henley, U.K.). Although the focus of this report is on the application of SPARTA to PID development, it is important to document the work carried out prior to SPARTA being available, in order to provide a complete record of the entire SFR-1 PID development effort as well as preserving the context of the multi-year project. Following a description of the different disposal sections of the SFR-1 and the various near-field barriers, the sequential development (i.e. near-field of Silo, BMA, BLA, BTF sections; far-field; integrated near-field + far-field) of the PID for SFR-1 repository system using Business Modeller is described. Owing to the complexity of the repository, in terms of number of both different disposal sections (Silo, BLA, BMA, BTF) and barriers associated with each section, the two-dimensional (2D) PID created for SFR-1 using Business Modeller is

  18. Modulation of near-field heat transfer between two gratings

    OpenAIRE

    Biehs , Svend-Age; Da Rosa , Felipe S. S.; Ben-Abdallah , Philippe

    2011-01-01

    International audience; We present a theoretical study of near-field heat transfer between two uniaxial anisotropic planar structures. We investigate how the distance and relative orientation (with respect to their optical axes) between the objects affect the heat flux. In particular, we show that by changing the angle between the optical axes it is possible in certain cases to modulate the net heat flux up to 90% at room temperature, and discuss possible applications of such a strong effect.

  19. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    International Nuclear Information System (INIS)

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-01-01

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials

  20. Near-field imaging of interacting nano objects with metal and metamaterial superlenses

    International Nuclear Information System (INIS)

    Hakkarainen, T; Setälä, T; Friberg, A T

    2012-01-01

    Employing rigorous electromagnetic theory we investigate optical the near-field imaging of two interacting dipole-like objects with metal and slightly lossy metamaterial nanoslab superlenses. Our analysis indicates that the dipole emission is suppressed by near-field interactions when the objects are close to the lens or each other. This strongly influences the image quality, in particular with objects of small size and high polarizability. The interference from two nearby objects also affects the resolution and subwavelength definition can only be obtained for objects with dipole moments predominantly orthogonal to the slab. Such an optimal imaging condition is achieved with excitation by total internal reflection. With simulations we show that in these circumstances, subwavelength resolutions of about λ/5 for silver superlens and λ/10 for metamaterial slab are reached. (paper)