WorldWideScience

Sample records for layered media theory

  1. Coherence theory of electromagnetic wave propagation through stratified N-layer media

    NARCIS (Netherlands)

    Hoenders, B.J.; Bertolotti, M.

    The theory of second-order coherence in connection with wave propagation through a stratified N-layer (SNL) medium is developed. Especially, the influence of the SNL medium on the propagation of the coherence generated by a given state of coherence at the entrance plane of the medium is considered.

  2. The Darwin procedure in optics of layered media and the matrix theory.

    Science.gov (United States)

    Dub; Litzman

    1999-07-01

    The Darwin dynamical theory of diffraction for two beams yields a nonhomogeneous system of linear algebraic equations with a tridiagonal matrix. It is shown that different formulae of the two-beam Darwin theory can be obtained by a uniform view of the basic properties of tridiagonal matrices, their determinants (continuants) and their close relationship to continued fractions and difference equations. Some remarks concerning the relation of the Darwin theory in the three-beam case to tridiagonal block matrices are also presented.

  3. Modeling multi-layer effects in passive microwave remote sensing of dry snow using Dense Media Radiative Transfer Theory (DMRT) based on quasicrystalline approximation

    Science.gov (United States)

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    The Dense Media Radiative Transfer theory (DMRT) of Quasicrystalline Approximation of Mie scattering by sticky particles is used to study the multiple scattering effects in layered snow in microwave remote sensing. Results are illustrated for various snow profile characteristics. Polarization differences and frequency dependences of multilayer snow model are significantly different from that of the single-layer snow model. Comparisons are also made with CLPX data using snow parameters as given by the VIC model. ?? 2007 IEEE.

  4. Scattering for wave equations with dissipative terms in layered media

    Directory of Open Access Journals (Sweden)

    Mitsuteru Kadowaki

    2011-05-01

    Full Text Available In this article, we show the existence of scattering solutions to wave equations with dissipative terms in layered media. To analyze the wave propagation in layered media, it is necessary to handle singular points called thresholds in the spectrum. Our main tools are Kato's smooth perturbation theory and some approximate operators.

  5. Media Effects: Theory and Research.

    Science.gov (United States)

    Valkenburg, Patti M; Peter, Jochen; Walther, Joseph B

    2016-01-01

    This review analyzes trends and commonalities among prominent theories of media effects. On the basis of exemplary meta-analyses of media effects and bibliometric studies of well-cited theories, we identify and discuss five features of media effects theories as well as their empirical support. Each of these features specifies the conditions under which media may produce effects on certain types of individuals. Our review ends with a discussion of media effects in newer media environments. This includes theories of computer-mediated communication, the development of which appears to share a similar pattern of reformulation from unidirectional, receiver-oriented views, to theories that recognize the transactional nature of communication. We conclude by outlining challenges and promising avenues for future research.

  6. MEDIA EFFECTS THEORIES

    Directory of Open Access Journals (Sweden)

    Elena MAFTEI-GOLOPENȚIA

    2015-11-01

    Full Text Available The complexity of the world and the various existing points of view play sometimes the role of barriers to understanding the events that take place around us or in which we are directly involved, that we may find overwhelming sometimes. In this context, we have no choice but to find instruments that can help us find a meaning beyond ”raw” information. Frames and other media effects theories can be this instrument, that can help us understand ”the stories” about the surrounding world. Frames are useful to us because our mind can’t simply process each new situation from scratch. This paper aims mainly at analysing frames, their function, their types, their roles and the levels at which they manifest themselves. It also represents the theoretical background of a future case study about the way in which the academic world is symbolically seen by the press.

  7. Photon transport through layered media

    CERN Document Server

    Masood, W

    1999-01-01

    The objective of this project is to study photon transport in layered media. In this regard the properties of the photon have been studied. The interactions that it makes with matter have been studied as well. ANISN code has been run for the sample problems regarding neutron and photon transport. As the project pertains to the transport of photons the layered media, therefore, photon energy spectrum was calculated using isotopes inventory calculation code ORIKAN which is run using 12 energy groups. The photon cross-section library used has a 21 group structure. The 12 group structure was expanded into 21 groups by using the method of histogram splitting. Calculations were made to find values of the energy transmitted at the outermost surface of the shield and then plotted for varying thicknesses of the shield. Finally, the results obtained have been discussed.

  8. The effects of layers in dry snow on its passive microwave emissions using dense media radiative transfer theory based on the quasicrystalline approximation (QCA/DMRT)

    Science.gov (United States)

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    A model for the microwave emissions of multilayer dry snowpacks, based on dense media radiative transfer (DMRT) theory with the quasicrystalline approximation (QCA), provides more accurate results when compared to emissions determined by a homogeneous snowpack and other scattering models. The DMRT model accounts for adhesive aggregate effects, which leads to dense media Mie scattering by using a sticky particle model. With the multilayer model, we examined both the frequency and polarization dependence of brightness temperatures (Tb's) from representative snowpacks and compared them to results from a single-layer model and found that the multilayer model predicts higher polarization differences, twice as much, and weaker frequency dependence. We also studied the temporal evolution of Tb from multilayer snowpacks. The difference between Tb's at 18.7 and 36.5 GHz can be S K lower than the single-layer model prediction in this paper. By using the snowpack observations from the Cold Land Processes Field Experiment as input for both multi- and single-layer models, it shows that the multilayer Tb's are in better agreement with the data than the single-layer model. With one set of physical parameters, the multilayer QCA/DMRT model matched all four channels of Tb observations simultaneously, whereas the single-layer model could only reproduce vertically polarized Tb's. Also, the polarization difference and frequency dependence were accurately matched by the multilayer model using the same set of physical parameters. Hence, algorithms for the retrieval of snowpack depth or water equivalent should be based on multilayer scattering models to achieve greater accuracy. ?? 2008 IEEE.

  9. Boundary-layer theory

    CERN Document Server

    Schlichting (Deceased), Hermann

    2017-01-01

    This new edition of the near-legendary textbook by Schlichting and revised by Gersten presents a comprehensive overview of boundary-layer theory and its application to all areas of fluid mechanics, with particular emphasis on the flow past bodies (e.g. aircraft aerodynamics). The new edition features an updated reference list and over 100 additional changes throughout the book, reflecting the latest advances on the subject.

  10. Crack layer theory

    Science.gov (United States)

    Chudnovsky, A.

    1984-01-01

    A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

  11. Multipole surface solitons in layered thermal media

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2008-01-01

    We address the existence and properties of multipole solitons localized at a thermally insulating interface between uniform or layered thermal media and a linear dielectric. We find that in the case of uniform media, only surface multipoles with less than three poles can be stable. In contrast, we reveal that periodic alternation of the thermo-optic coefficient in layered thermal media makes possible the stabilization of higher order multipoles.

  12. Simulation of the microwave emission of multi-layered snowpacks using the dense media radiative transfer theory: the DMRT-ML model

    Directory of Open Access Journals (Sweden)

    G. Picard

    2012-11-01

    Full Text Available DMRT-ML is a physically-based numerical model designed to compute the thermal microwave emission of a given snowpack. Its main application is the simulation of brightness temperatures at frequencies in the range 1–200 GHz similar to those acquired routinely by space-based microwave radiometers. The model is based on the Dense Media Radiative Transfer (DMRT theory for the computation of the snow scattering and extinction coefficients and on the Discrete Ordinate Method (DISORT to numerically solve the radiative transfer equation. The snowpack is modeled as a stack of multiple horizontal snow layers and an optional underlying interface representing the soil or the bottom ice. The model handles both dry and wet snow conditions. Such a general design allows the user to account for a wide range of snow conditions. Hitherto, the model has been used to simulate the thermal emission of the deep firn on ice sheets, shallow snowpacks overlying soil in Arctic and Alpine regions, and overlying ice on the large ice-sheet margins and glaciers. DMRT-ML has thus been validated in three very different conditions: Antarctica, Barnes Ice Cap (Canada and Canadian tundra. It has been recently used in conjunction with inverse methods to retrieve snow grain size from remote sensing data. The model is written in Fortran90 and available to the snow remote sensing community as an open-source software.

  13. Simulation of the microwave emission of multi-layered snowpacks using the Dense Media Radiative transfer theory: the DMRT-ML model

    Directory of Open Access Journals (Sweden)

    G. Picard

    2013-07-01

    Full Text Available DMRT-ML is a physically based numerical model designed to compute the thermal microwave emission of a given snowpack. Its main application is the simulation of brightness temperatures at frequencies in the range 1–200 GHz similar to those acquired routinely by space-based microwave radiometers. The model is based on the Dense Media Radiative Transfer (DMRT theory for the computation of the snow scattering and extinction coefficients and on the Discrete Ordinate Method (DISORT to numerically solve the radiative transfer equation. The snowpack is modeled as a stack of multiple horizontal snow layers and an optional underlying interface representing the soil or the bottom ice. The model handles both dry and wet snow conditions. Such a general design allows the model to account for a wide range of snow conditions. Hitherto, the model has been used to simulate the thermal emission of the deep firn on ice sheets, shallow snowpacks overlying soil in Arctic and Alpine regions, and overlying ice on the large ice-sheet margins and glaciers. DMRT-ML has thus been validated in three very different conditions: Antarctica, Barnes Ice Cap (Canada and Canadian tundra. It has been recently used in conjunction with inverse methods to retrieve snow grain size from remote sensing data. The model is written in Fortran90 and available to the snow remote sensing community as an open-source software. A convenient user interface is provided in Python.

  14. Simulation of the Microwave Emission of Multi-layered Snowpacks Using the Dense Media Radiative Transfer Theory: the DMRT-ML Model

    Science.gov (United States)

    Picard, G.; Brucker, Ludovic; Roy, A.; Dupont, F.; Fily, M.; Royer, A.; Harlow, C.

    2013-01-01

    DMRT-ML is a physically based numerical model designed to compute the thermal microwave emission of a given snowpack. Its main application is the simulation of brightness temperatures at frequencies in the range 1-200 GHz similar to those acquired routinely by spacebased microwave radiometers. The model is based on the Dense Media Radiative Transfer (DMRT) theory for the computation of the snow scattering and extinction coefficients and on the Discrete Ordinate Method (DISORT) to numerically solve the radiative transfer equation. The snowpack is modeled as a stack of multiple horizontal snow layers and an optional underlying interface representing the soil or the bottom ice. The model handles both dry and wet snow conditions. Such a general design allows the model to account for a wide range of snow conditions. Hitherto, the model has been used to simulate the thermal emission of the deep firn on ice sheets, shallow snowpacks overlying soil in Arctic and Alpine regions, and overlying ice on the large icesheet margins and glaciers. DMRT-ML has thus been validated in three very different conditions: Antarctica, Barnes Ice Cap (Canada) and Canadian tundra. It has been recently used in conjunction with inverse methods to retrieve snow grain size from remote sensing data. The model is written in Fortran90 and available to the snow remote sensing community as an open-source software. A convenient user interface is provided in Python.

  15. Manganese containing layer for magnetic recording media

    Science.gov (United States)

    Lambeth, David N.; Lee, Li-Lien; Laughlin, David E.

    1999-01-01

    The present invention provides for a magnetic recording media incorporating Mn-containing layers between a substrate and a magnetic layer to provide media having increased coercivity and lower noise. The Mn-containing layer can be incorporated in a rotating, translating or stationary recording media to operate in conjunction with magnetic transducing heads for recording and reading of magnetic data, as well as other applications. The magnetic recording medium of the invention preferably includes a Co or Co alloy film magnetic layer, and Mn-containing layer, preferably comprised of VMn, TiMn, MnZn, CrMnMo, CrMnW, CrMnV, and CrMnTi, and most preferably a CrMn alloy, disposed between the substrate and the magnetic layer to promote an epitaxial crystalline structure in the magnetic layer. The medium can further include seed layers, preferably polycrystalline MgO for longitudinal media, underlayers, and intermediate layers. Underlayers and intermediate layers are comprised of materials having either an A2 structure or a B2-ordered crystalline structure disposed between the seed layer and the magnetic layer. Materials having an A2 structure are preferably Cr or Cr alloys, such as CrV, CrMo, CrW and CrTi. Materials having a B2-ordered structure having a lattice constant that is substantially comparable to that of Cr, such as those preferably selected from the group consisting of NiAl, AILCo, FeAl, FeTi, CoFe, CoTi, CoHf, CoZr, NiTi, CuBe, CuZn, A-LMn, AlRe, AgMg, and Al.sub.2 FeMn.sub.2, and is most preferably FeAl or NiAl.

  16. Application Layer Multicast Technology of Streaming Media

    Directory of Open Access Journals (Sweden)

    Jiansheng Liu

    2011-08-01

    Full Text Available With the rapid development of network technology, Internet business has been transferred from a simple text into a host text, audio, video and other streaming services. Application layer multicast is one of the key technologies to protect the large-scale service quality of streaming media system, which has become an important part of study. Based on the application layer multicast technology, it focused on analyzing the effects of application layer multicast to the  large-scale of media streaming system, and summarized the typical characteristics of the system. It takes efficiency of multicast robustness, scalability, and the continuity as evaluation indexes, and summarized the typical multicast. In the end,the drawbacks and develop directions of application layer multicast were discussed.

  17. Micromagnetic theory of antiferromagnetically coupled magnetic recording media

    Science.gov (United States)

    Schabes, Manfred

    2001-03-01

    The micromagnetic theory of antiferromagnetically coupled magnetic recording media (AFC media) is discussed for the case of AFC media consisting of two ferromagnetic layers and a polarization layer.[1-2] Attention is focused on AFC media where the top layer governs the remanent magnetization while the bottom layer acts as a slave layer. Micromagnetic simulations of recorded bit transitions demonstrate a good anticorrelation of the layer magnetizations at bit transitions for this case. Calculation of MR readback pulses shows that these AFC media have pulse widths of a thin single layer magnetic recording medium with an effective MrT that is approximately given by the difference in MrT's of the top and bottom layers. Magnetic stability is set to first order by the thicker top layer and the interactions between the top and bottom layers. [1] E.E. Fullerton, D.T. Margulies, M.E. Schabes, M. Carey, B. Gurney, A. Moser, M. Best, G. Zeltzer, K. Rubin, H. Rosen, Appl. Phys. Lett. 77 (2000), 3806. [2] E.N. Abarra, A. Inomata, H. Sato, I. Okamoto, Y. Mizoshita, Appl. Phys. Lett. 77 (2000), 2581.

  18. Shock dynamics in layered periodic media

    KAUST Repository

    Ketcheson, David I.

    2012-01-01

    Solutions of constant-coeffcient nonlinear hyperbolic PDEs generically develop shocks, even if the initial data is smooth. Solutions of hyperbolic PDEs with variable coeffcients can behave very differently. We investigate formation and stability of shock waves in a one-dimensional periodic layered medium by a computational study of time-reversibility and entropy evolution. We find that periodic layered media tend to inhibit shock formation. For small initial conditions and large impedance variation, no shock formation is detected even after times much greater than the time of shock formation in a homogeneous medium. Furthermore, weak shocks are observed to be dynamically unstable in the sense that they do not lead to significant long-term entropy decay. We propose a characteristic condition for admissibility of shocks in heterogeneous media that generalizes the classical Lax entropy condition and accurately predicts the formation or absence of shocks in these media.

  19. The Application of Layer Theory to Design: The Control Layer

    Science.gov (United States)

    Gibbons, Andrew S.; Langton, Matthew B.

    2016-01-01

    A theory of design layers proposed by Gibbons ("An Architectural Approach to Instructional Design." Routledge, New York, 2014) asserts that each layer of an instructional design is related to a body of theory closely associated with the concerns of that particular layer. This study focuses on one layer, the control layer, examining…

  20. Mediatization Theory and Digital Media

    DEFF Research Database (Denmark)

    Finnemann, Niels Ole

    2011-01-01

    In the 20th century, the term "media logic" was introduced to denote the influence of independent mass media on political systems and other institutions. In recent years the idea has been reworked and labelled "mediatization" to widen the framework by including new media and new areas of applicat......In the 20th century, the term "media logic" was introduced to denote the influence of independent mass media on political systems and other institutions. In recent years the idea has been reworked and labelled "mediatization" to widen the framework by including new media and new areas...... new trajectories made possible by these media, which have led into a new media matrix built around the internet and mobile devices. It will be argued that the new media matrix cannot be understood from a point of view defined by the framework of 20th century mass media because digital media open new...

  1. Mediatization Theory and Digital Media

    DEFF Research Database (Denmark)

    Finnemann, Niels Ole

    2011-01-01

    of application.  In Section Two the paper discusses different conceptualizations. It is argued that even if they bring new insights, they cannot be unified into one concept, and that they also lack a consistent definition of digital media. Section three provides a definition of digital media in order to identify...... new trajectories made possible by these media, which have led into a new media matrix built around the internet and mobile devices. It will be argued that the new media matrix cannot be understood from a point of view defined by the framework of 20th century mass media because digital media open new......In the 20th century, the term "media logic" was introduced to denote the influence of independent mass media on political systems and other institutions. In recent years the idea has been reworked and labelled "mediatization" to widen the framework by including new media and new areas...

  2. Field theory approaches to new media practices

    DEFF Research Database (Denmark)

    Hartley, Jannie Møller; Willig, Ida; Waltorp, Karen

    2015-01-01

    to develop field theory in this context. Secondly, we present the four thematic articles in this issue and the articles outside the theme, which includes two translations of classic texts within communication and media research. This introduction article concludes by encouraging media scholars to embark...... on more studies within a field theory framework, as the ability of the comprehensive theoretical work and the ideas of a reflexive sociology is able to trigger the good questions, more than it claims to offer a complete and self-sufficient sociology of media and inherent here also new media....

  3. Nonlinear Acoustic Wave Interactions in Layered Media.

    Science.gov (United States)

    1980-03-06

    Generated Components in Dispersive Media. . . . . . . . . . . . . 62 4.4 Dispersion in Medium II . . . . . . . . .. 68 V. CONCLUSIONS...give rise to leaky wave modes which are more thoroughly discussed 17 18 by Kapany and Burke, and by Marcuse . Leaky modes are C.C. Ghizoni, J.M...1977), 843-848. 1 7N.S. Kapany and J.J. Burke, Optical Waveeeuides, (New York: Academic Press, 1972), pp. 24-34. D. Marcuse , Theory of Dielectric Optical

  4. Learning Theory, Educational Media and Individualized Instruction

    Science.gov (United States)

    Gagne, Robert M.

    1970-01-01

    An examination of learning theory and its applicability to the design of effective individualized instruction. The article also discusses the need to consider learning objectives when choosing media to perform instructional functions. (AA)

  5. Localization length fluctuation in randomly layered media

    Science.gov (United States)

    Yuan, Haiming; Huang, Feng; Jiang, Xiangqian; Sun, Xiudong

    2016-10-01

    Localization properties of the two-component randomly layered media (RLM) are studied in detail both analytically and numerically. The localization length is found fluctuating around the analytical result obtained under the high-frequency limit. The fluctuation amplitude approaches zero with the increasing of disorder, which is characterized by the distribution width of random thickness. It is also found that the localization length over the mean thickness periodically varies with the distribution center of random thickness. For the multi-component RLM structure, the arrangement of material must be considered.

  6. Inversion of H/V in layered media from seismic ambient noise based on the diffuse field theory and on improved calculation of Green functions

    Science.gov (United States)

    Sánchez-Sesma, Francisco J.; Piña, José; García-Jerez, Antonio; Luzón, Francisco; Perton, Mathieu

    2014-05-01

    The microtremor H/V spectral ratio (MHVSR) is widely used to assess the dominant frequency of soil sites. Measurements are relatively simple as only one station is needed. It has been recently proposed a theoretical basis linking ambient noise vibrations with diffuse field theory. In this theory the directional energy density computed as the average spectral density of motion at a point, is proportional to the imaginary part of Green function at the observation point. Appropriate normalization is crucial to make the experimental spectral ratios closer to the theoretical counterpart. According to this theory the square of H/V is twice the ratio ImG11 / ImG33, where ImG11 and ImG33 are the imaginary part of Green functions at the load point for horizontal and vertical components, respectively. In order to efficiently compute the imaginary part of Green's functions in a layered medium we start from an integral on the complex k plane and, using Harkrider's nomenclature, separate formulae for body-, Rayleigh-, and Love-wave components to the spectral densities are obtained. Then the poles allow for integration using the Cauchy residue theorem plus some contributions from branch integrals. It is possible to isolate pseudo reflections from ImG11 and thus constrain the inversion of soil profile. We assess ImG11 removing the influence of illumination spectrum using the H/V spectral ratio and an estimate of ImG33 (from an a priori model) by means of ImG11=0.5(H/V )2*ImG33. It has been found that ImG33 is less sensitive to details of stratigraphy. In fact, the Poisson ratio of the uppermost layer controls the slope in high frequency. With the obtained model ImG33 can be updated and the estimate of ImG11 will be improved. ACKNOWLEDGEMENTS. This research has been partially supported by DGAPA-UNAM under Project IN104712, by the MINECO research project CGL2010-16250, Spain, by the EU with FEDER, and the AXA Research Fund.

  7. Spectral ratios of ambient noise based on the diffuse field theory: Improved inversion of H/V in layered media using analytical properties of Green functions

    Science.gov (United States)

    Sanchez-Sesma, F. J.; Perton, M.; Piña, J.; Luzón, F.; Garcia-Jerez, A.; Rodriguez-Castellanos, A.

    2013-12-01

    It is well know the popularity of H/V spectral ratio to extract the dominant frequency of soil sites for microzonation studies (Nakamura, 1989). It is relatively easy to make measurements as only one station is needed. Despite its success, this approach had not solid theoretical basis until a proposal to link ambient noise vibrations with diffuse field theory was made (Sánchez-Sesma et al, 2011a). Based on this theory the average spectral density of a given motion of a point, also called directional energy density (Perton et al, 2009), is proportional to the imaginary part of Green function precisely at the observation point. The proportionality implies that vector components are all multiplied by the current spectral level of the diffuse illumination. Appropriate normalization is crucial to make the experimental spectral ratios closer to the theoretical counterpart. According to this theory the square of H/V is twice the ratio of ImG11 and ImG33, where ImG11 and ImG33 are the imaginary part of Green functions at the load point for horizontal and vertical components, respectively. From ImG11 it could be possible through Fourier analysis to extract pseudo reflections and thus constrain the inversion of soil profile. We propose to assess ImG11 removing the influence of illumination spectrum using the H/V spectral ratio and an estimate of ImG33 (obtained from a priori model) by means of ImG11=0.5(H/V)2*ImG33. It has been found that ImG33 is less sensitive to details of stratigraphy. In fact, the most relevant property is the Poisson ratio of the uppermost layer which controls the slope in high frequency (Sánchez-Sesma et al, 2011b). Pseudo-reflection seismograms are thus obtained from Fourier transform, back to time domain, of i{ImG11-ImG11HSS}, where ImG11HSS is the imaginary part of Green functions at the load point for horizontal load at the surface of a half-space with the properties of the uppermost layer. With the obtained model ImG33 can be updated and the

  8. Nero Zero Frequency Sounding in Layered Media

    Science.gov (United States)

    Autry, Chastity; Tamasan, Alexandru; Veras, Johann

    2009-11-01

    We consider the mathematical model of frequency sounding of a continuously layered media. By the means of frequency asymptotic expansion of the wave field, this problem is equivalent to an inverse boundary value problem for the Ricatti equation. We solve the inverse Ricatti problem via a Cauchy problem for a first order quadratic equation for sequence-valued maps. The quadratic equation contains no unknown coefficients. The information of the medium is encoded in the initial value. For specific data, the Cauchy problem has a unique solution. Based on the contraction mapping principle the method of proof provides a stable reconstruction algorithm. The computational feasibility of the proposed approach is demonstrated in a numerical experiment.

  9. Field theory approaches to new media practices

    DEFF Research Database (Denmark)

    Willig, Ida; Waltorp, Karen; Hartley, Jannie Møller

    2015-01-01

    This special issue of MedieKultur specifically addresses new media practices and asks how field theory approaches can help us understand how culture is (prod)used via various digital platforms. In this article introducing the theme of the special issue, we argue that studies of new media practice...... of a reflexive sociology are capable of prompting important questions without necessarily claiming to offer a complete and self-sufficient sociology of media, including new media.......This special issue of MedieKultur specifically addresses new media practices and asks how field theory approaches can help us understand how culture is (prod)used via various digital platforms. In this article introducing the theme of the special issue, we argue that studies of new media practices...... could benefit particularly from Pierre Bourdieu’s research on cultural production. We introduce some of the literature that concerns digital media use and has been significant for field theory’s development in this context. We then present the four thematic articles in this issue and the articles...

  10. Theory of deflagration in disordered media.

    Science.gov (United States)

    Schiulaz, Mauro; Laumann, Christopher R; Balatsky, Alexander V; Spivak, Boris Z

    2017-03-01

    The conventional theory of burning works well in the case of uniform media where all system parameters are spatially independent. We develop a theory of burning in disordered media. In this case, rare regions (hot spots) where the burning process is more effective than on average may control the heat propagation in an explosive sample. We show that most predictions of the theory of burning are quite different from the conventional case. In particular, we show that a system of randomly distributed hot spots exhibits a dynamic phase transition, which is similar to the percolation transition. Depending on parameters of the system the phase transition can be either first or second order. These two regimes are separated by a tricritical point. The above results may be applicable to dynamics of any overheated disordered system with a first order phase transition.

  11. Immersed in media telepresence theory, measurement & technology

    CERN Document Server

    Lombard, Matthew; Freeman, Jonathan; IJsselsteijn, Wijnand; Schaevitz, Rachel J

    2015-01-01

    Highlights key research currently being undertaken within the field of telepresence, providing the most detailed account of the field to date, advancing our understanding of a fundamental property of all media - the illusion of presence; the sense of "being there" inside a virtual environment, with actual or virtual others. This collection has been put together by leading international scholars from America, Europe, and Asia. Together, they describe the state-of-the-art in presence theory, research and technology design for an advanced academic audience. Immersed in Media provides research t

  12. Hurricane Boundary-Layer Theory

    Science.gov (United States)

    2010-01-01

    2501. Kundu PK. 1990. Fluid Mechanics . Academic Press: San Diego, USA. Kuo HL. 1982. Vortex boundary layer under quadratic surface stress. Boundary...identification of two mechanisms for the spin-up of the mean tangential circulation of a hurricane. The first involves convergence of absolute angular...momentum above the boundary layer, where this quantity is approximately conserved. This mechanism acts to spin up the outer circulation at radii

  13. Study on Folds of Equal Thickness Multi-layer Sandwiched in Different Thickness Media

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The theoretical model and non-homogeneous differential equation of equal thickness multi-layer folds sandwiched in different thickness and same character media are established by elastic and plastic mechanics. The special answer of the non-homogeneous differential equation and the common answer of the homogeneous differential equation are deduced by applying logistic equation and special function, and the dominant wavelength theory of equal thickness multi-layer folds sandwiched in different thickness and same character media. In addition, the experimental folding in both elastic and sticky materials proves the dominant wavelength theory.

  14. Thermally stable magnetic media based on antiferromagnetically coupled layers

    Science.gov (United States)

    Fullerton, Eric E.

    2001-03-01

    The combination of signal-to-noise requirements, write field limitations, and thermal activation of small particles is thought to limit the potential areal density of longitudinal media and is commonly referred to as the "superparamagnetic limit". Recording media composed of antiferromagnetically coupled (AFC) magnetic recording layers is a promising approach to extend areal densities of longitudinal media beyond these perceived limits [1,2]. The recording medium is made up of two ferromagnetic recording layer separated by a nonmagnetic layer whose thickness is tuned to couple the layers antiferromagnetically. For such a structure, the effective areal moment density (Mrt) of the composite structure is given by the difference between the ferromagnetic layers allowing the effective magnetic thickness to scale independently of the physical thickness of the media. The resulting media appears magnetically thin while being physically thick and, thus, allows AFC media to maintain thermal stability even for low Mrt values. Experimental realization of this concept using CoPtCrB alloy layers that demonstrates thermally stable low-Mrt media suitable for high-density recording will be discussed. This work is done in collaboration with D. T. Margulies, M. E. Schabes,M. Doerner, M. Carey, B. Gurney, A. Moser, M. Best, G. Zeltzer, K. Rubin, and H. Rosen. [1]. Fullerton et al., Appl. Phys. Lett. 77, 3806 (2000). [2]. Abarra et al., Appl. Phys. Lett. 77, 2581 (2000).

  15. Self-guiding light in layered nonlinear media

    DEFF Research Database (Denmark)

    Bergé, L.; Mezentsev, V. K.; Juul Rasmussen, Jens;

    2000-01-01

    We study the propagation of intense optical beams in layered Kerr media. With appropriate shapes, beams with a power close to the self-focusing threshold are shown to propagate over long distances as quasistationary waveguides in cubic media supporting a periodic nonlinear refractive index. (C...

  16. Theory of porous media - past and present

    Energy Technology Data Exchange (ETDEWEB)

    Boer, R. de [Essen Univ. (Germany). Inst. fuer Mechanik

    1998-10-01

    Porous solids filled with liquid or gas play an important role in engineering, e.g., in material science, petroleum industry, chemical engineering, and soil mechanics as well as in biomechanics. Although porous media are of considerable practical significance the description of their mechanical and thermodynamical behavior has been unsatisfactory for a long time. The theory to describe the complex thermodynamical behavior of such saturated porous solids has come to certain well-founded conclusions only recently. It is the goal of this paper to show the historical development of the porous media theory, which already started in the eighteenth century, formed in some areas by polemic disputes and tragic events in the lifes of the scientists involved. Furthermore, the current state of the research into this subject is discussed, whereby the state of the development of the material independent basic equations and the constitutive theory is illustrated. For a certain class of models general theorems, such as minimum and maximum problems, are derived and the uniqueness of solutions of boundary value problems is proved. (orig.)

  17. Critical Media Literacy in Action: Uniting Theory, Practice and Politics in Media Education

    Science.gov (United States)

    Thevenin, Benjamin Joseph

    2012-01-01

    As media literacy is a growing field, there exist a number of distinct approaches to media education with varied political significance. Approaches such as protectionism, media arts education, and critical media literacy draw upon diverse theoretical traditions. Often overlooked in these traditions is the Critical Theory of the Frankfurt School.…

  18. Turbulent Boundary Layers - Experiments, Theory and Modelling

    Science.gov (United States)

    1980-01-01

    DEVELOPMENT (ORGANISATION DU TRAITE DE L’ATLANTIQUE NORD ) AGARD Conference Proceedings No.271 TURBULENT BOUNDARY LAYERS - EXPERIMENTS, THEORY AND...photographs of Figures 21 and 22. In this case, the photographs are taken with a single flash strobe and thus yield the instantaneous positions of the

  19. Nonlinear Ekman Layer Theories and Their Applications

    Institute of Scientific and Technical Information of China (English)

    TAN Zhemin; FANG Juan; WU Rongsheng

    2006-01-01

    Based on the classical Ekman theory, a series of intermediate boundary layer models, which retain the nonlinear advective process while discard embellishments, have been proposed with the intention to understand the complex nonlinear features of the atmospheric boundary layer and its interaction with the free atmosphere. In this paper, the recent advances in the intermediate boundary-layer dynamic models are reviewed. Several intermediate models such as the boundary-layer models incorporating geostrophic momentum approximation, Ekman momentum approximation, and the weak nonlinear Ekman-layer model are a major theme.With inspection of the theoretical frameworks, the physical meaning and the limitations of each intermediate model are discussed. It is found that the qualitative descriptions of the nonlinear nature in Ekman layer made by the intermediate models are fairly consistent though the details may be different. As the application of the intermediate models is concerned, the application of the intermediate models to the study of the topographic boundary layer, frontogenesis, low-level frontal structure, and low-level jet are especially summarized in this paper. It is shown that the intermediate boundary-layer models have great potential in illustrating the low-level structures of the weather and climate systems as they are coupled with the free atmospheric models.In addition, the important remaining scientific challenges and a prospectus for future research on the intermediate model are also discussed.

  20. A Model with Ellipsoidal Scatterers for Polarimetric Remote Sensing of Anisotropic Layered Media

    Science.gov (United States)

    Nghiem, S. V.; Kwok, R.; Kong, J. A.; Shin, R. T.

    1993-01-01

    This paper presents a model with ellipsoidal scatterers for applications to polarimetric remote sensing of anisotropic layered media at microwave frequencies. The physical configuration includes an isotropic layer covering an anisotropic layer above a homogeneous half space. The isotropic layer consists of randomly oriented spheroids. The anisotropic layer contains ellipsoidal scatterers with a preferential vertical alignment and random azimuthal orientations. Effective permittivities of the scattering media are calculated with the strong fluctuation theory extended to account for the nonspherical shapes and the scatterer orientation distributions. On the basis of the analytic wave theory, dyadic Green's functions for layered media are used to derive polarimetric backscattering coefficients under the distorted Born approximation. The ellipsoidal shape of the scatterers gives rise to nonzero cross-polarized returns from the untilted anisotropic medium in the first-order approximation. Effects of rough interfaces are estimated by an incoherent addition method. Theoretical results and experimental data are matched at 9 GHz for thick first-year sea ice with a bare surface and with a snow cover at Point Barrow, Alaska. The model is then used to study the sensitivity of polarimetric backscattering coefficients with respect to correlation lengths representing the geometry of brine inclusions. Polarimetric signatures of bare and snow-covered sea ice are also simulated based on the model to investigate effects of different scattering mechanisms.

  1. Percolation theory for flow in porous media

    CERN Document Server

    Hunt, Allen; Ghanbarian, Behzad

    2014-01-01

    This monograph presents, for the first time, a unified and comprehensive introduction to some of the basic transport properties of porous media, such as electrical and hydraulic conductivity, air permeability and diffusion. The approach is based on critical path analysis and the scaling of transport properties, which are individually described as functions of saturation. At the same time, the book supplies a tutorial on percolation theory for hydrologists, providing them with the tools for solving actual problems. In turn, a separate chapter serves to introduce physicists to some of the language and complications of groundwater hydrology necessary for successful modeling. The end-of-chapter problems often indicate open questions, which young researchers entering the field can readily start working on. This significantly revised and expanded third edition includes in particular two new chapters: one on advanced fractal-based models, and one devoted to the discussion of various open issues such as the role of d...

  2. Wave propagation in layered anisotropic media with application to composites

    CERN Document Server

    Nayfeh, AH

    1995-01-01

    Recent advances in the study of the dynamic behavior of layered materials in general, and laminated fibrous composites in particular, are presented in this book. The need to understand the microstructural behavior of such classes of materials has brought a new challenge to existing analytical tools. This book explores the fundamental question of how mechanical waves propagate and interact with layered anisotropic media. The chapters are organized in a logical sequence depending upon the complexity of the physical model and its mathematical treatment.

  3. The crosswell electromagnetic response of layered media

    Energy Technology Data Exchange (ETDEWEB)

    Deszcz-Pan, Maria [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1994-04-01

    Crosswell electromagnetic measurements are a promising new geophysical technique for mapping subsurface electrical conductivity which can provide information about the subsurface distribution of water, oil or steam. In this work the fields from a low frequency vertical magnetic dipole have been examined from the specific point of view of their application to the determination of the conductivity of a layered medium. The source and the receiver were placed inside two separate boreholes. The range of penetration of such a crosswell system for typical earth resistivities and for currently available transmitter and receiver technologies was found to be up to 1,000 meters so problems in ground water and petroleum reservoir characteristics can be practically examined. An analysis of the behavior of the magnetic fields at the boundary between two half-spaces showed that the horizontal magnetic field component, H{rho}, and the vertical derivative of a vertical component, {delta}H{sub z}/{delta}z, are more sensitive to conductivity variations than H{sub z}. The analysis of derivatives led to the concept of measuring the conductivity directly using a second vertical derivative of H{sub z}. Conductivity profiles interpreted from field data using this technique reproduced accurately the electrical logs for a test site near Devine, Texas. It was found in this study that the inversion techniques are more stable when the first vertical derivative of H{sub z} is used rather than H{sub z} itself. Using data from a salt water injection experiment at the Richmond Field test site in Berkeley it was also found that these robust layer inversions were successful in identifying the preferential flow direction of the injected brine to four boreholes surrounding the injection well.

  4. Time-resolved photon emission from layered turbid media

    Energy Technology Data Exchange (ETDEWEB)

    Hielscher, A.H. [Department of Electrical and Computer Engineering, Rice University, 6100 South Main, Houston, Texas 77251-1892 (United States); Liu, H.; Chance, B. [Department of Biochemistry and Biophysics, University of Pennsylvania, D501 Richards Building, Philadelphia, Pennsylvania 19104-6089 (United States); Tittel, F.K. [Department of Electrical and Computer Engineering, Rice University, 6100 South Main, Houston, Texas 77251-1892 (United States); Jacques, S.L. [Laser Biology Research Laboratory, Box 17, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)

    1996-02-01

    We present numerical and experimental results of time-resolved emission profiles from various layered turbid media. Numerical solutions determined by time-resolved Monte Carlo simulations are compared with measurements on layered-tissue phantoms made from gelatin. In particular, we show that in certain cases the effects of the upper layers can be eliminated. As a practical example, these results are used to analyze {ital in} {ital vivo} measurements on the human head. This demonstrates the influence of skin, skull, and meninges on the determination of the blood oxygenation in the brain. {copyright} {ital 1996 Optical Society of America.}

  5. Dynamic aspects of apparent attenuation and wave localization in layered media

    Science.gov (United States)

    Haney, M.M.; Van Wijk, K.

    2008-01-01

    We present a theory for multiply-scattered waves in layered media which takes into account wave interference. The inclusion of interference in the theory leads to a new description of the phenomenon of wave localization and its impact on the apparent attenuation of seismic waves. We use the theory to estimate the localization length at a CO2 sequestration site in New Mexico at sonic frequencies (2 kHz) by performing numerical simulations with a model taken from well logs. Near this frequency, we find a localization length of roughly 180 m, leading to a localization-induced quality factor Q of 360.

  6. Degree-layer theory of network topology

    CERN Document Server

    Zhou, Bin; Zhe, He

    2014-01-01

    The network topology can be described by the number of nodes and the interconnections among them. The degree of a node in a network is the number of connections it has to other nodes and the degree distribution is the probability distribution of these degrees over the whole network. Therefore, the degree is very important structural parameter of network topology. However, given the number of nodes and the degree of each node in a network, the topology of the network cannot be determined. Therefore, we propose the degree-layer theory of network topology to describe deeply the network topology. First, we propose the concept of degree-tree with the breadth-first search tree. The degrees of all nodes are layered and have a hierarchical structure. Second,the degree-layer theory is described in detail. Two new concepts are defined in the theory. An index is proposed to quantitatively distinguish the two network topologies. It also can quantitatively measure the stability of network topology built by a model mechani...

  7. Calculation Method for Media in Ball Mills by Layers

    Institute of Scientific and Technical Information of China (English)

    徐志强; 张荣曾; 曾鸣

    2002-01-01

    Based on analyzing the moving principle of media in ball mill, it is implicated that there is the significant difference of movement situation among each single layer. A new method to calculate each single was put forward. The results from lab experiment and actual data from 26 sets industrial mills state indicate that the new calculation method reaches the high accuracy with excellent practicab ility.

  8. Theory of Creative Advertising Creative and Media

    Institute of Scientific and Technical Information of China (English)

    郭晨

    2013-01-01

    with the rapid development of society, in people's daily life, advertising creative and media ideas gradual y occupied most of the people's life, and play a huge market driving force. This paper mainly analyzes the creative advertising creative and the media of different location and meaning, to explain the inner link between both.

  9. Application of K-integrals to radiative transfer in layered media

    CERN Document Server

    Selden, Adrian C

    2016-01-01

    Simple yet accurate results for radiative transfer in layered media with discontinuous refractive index are obtained by the method of K-integrals, originally developed for neutron transport analysis. These are certain weighted integrals applied to the angular intensity distribution at the refracting boundaries. The radiative intensity is expressed as the sum of the asymptotic angular intensity distribution valid in the depth of the scattering medium and a transient term valid near the boundary. Integral boundary conditions are obtained from the vanishing of the K-integrals of the boundary transient, yielding simple linear equations for the intensity coefficients (two for a halfspace, four for a slab or an interface), enabling the angular emission intensity and the diffuse reflectance (albedo) and transmittance of the scattering layer to be calculated. The K-integral method is orders of magnitude more accurate than diffusion theory and can be applied to scattering media with a wide range of scattering albedoes...

  10. Quantum optical effective-medium theory for layered metamaterials

    CERN Document Server

    Amooghorban, Ehsan

    2016-01-01

    The quantum optics of metamaterials starts with the question whether the same effective-medium theories apply as in classical optics. In general the answer is negative. For active plasmonics but also for some passive metamaterials, we show that an additional effective-medium parameter is indispensable besides the effective index, namely the effective noise-photon distribution. Only with the extra parameter can one predict how well the quantumness of states of light is preserved in the metamaterial. The fact that the effective index alone is not always sufficient and that one additional effective parameter suffices in the quantum optics of metamaterials is both of fundamental and practical interest. Here from a Lagrangian description of the quantum electrodynamics of media with both linear gain and loss, we compute the effective noise-photon distribution for quantum light propagation in arbitrary directions in layered metamaterials, thereby detailing and generalizing our recent work [ E. Amooghorban et al., Ph...

  11. Wartawan Media Now dalam Mengemas Berita: Perspektif Situational Theory

    Directory of Open Access Journals (Sweden)

    Dasrun Hidayat

    2015-07-01

    Full Text Available The study aims to map and describe relationships between concepts of activity of journalists in the media now cloning technology based activities and relationship between news reporters. This study discusses the focus of news coverage in media activities and relationships among the journalists in the era of technology. The theory used is situational theory Grunig and Hunt and descriptive method of Public Relations. The study found that the situation changes in the era of media encourage actions of unscrupulous hunters cloning news. News media such as online media should now be used as the initial data is not the primary data news writing. The presence of media now facilitates the work of journalists but not always produce good quality of news. Otherwise, the presence of technology encourages more active cloning news reporter. Media now can initiate active and apathetic public situations as influenced by quality news content. The presence of media technology changes the image of the relationship between journalists—from person to person or reporter to reporter to journalists with media technology.

  12. ON FREE WAVE PROPAGATION IN ANISOTROPIC LAYERED MEDIA

    Institute of Scientific and Technical Information of China (English)

    Yongqiang Guo; Weiqiu Chen

    2008-01-01

    The method of reverberation-ray matrix (MRRM) is extended and modified for the analysis of free wave propagation in anisotropic layered elastic media. A general, numerically stable formulation is established within the state space framework. The compatibility of physical variables in local dual coordinates gives the phase relation, from which exponentially growing functions are excluded. The interface and boundary conditions lead to the scattering relation,which avoids matrix inversion operation. Numerical examples are given to show the high accuracy of the present MRRM.

  13. Projection Theory and Its Application into Media Discourse Analysis

    Institute of Scientific and Technical Information of China (English)

    邵宏

    2008-01-01

    Projection is a kind of logical-semantic relation which refers to the phenomenon that the secondary clause is projected through the primary clause, which instates it as a locution or an idea. Halliday conducts the basic research on projection from the functional perspective. Then Martin and Zeng try to develop Halliday's projection theory, resulting in a comprehensive framework of projection. Finally the projection theory is applied into the analysis of a sample media discourse. And projection theory is of great help in its application into media discourse analysis.

  14. Framing as a Theory of Media Effects.

    Science.gov (United States)

    Scheufele, Dietram A.

    1999-01-01

    Systematizes the fragmented approaches to framing in political communication and integrates them into a comprehensive model. Classifies previous approaches to framing research along two dimensions: media frames versus audience frames; and the way frames are operationalized (independent variable or dependent variable). Identifies four key processes…

  15. Random Boundary Simulation of Pumping Groundwater on Two-layer Soft Soil Structure with Porous Media

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on random theory,fluid dynamics,porous media and soil mechanics,the porosity and random characteristic of the two-layer soft soil in Wuhan region were studied in this paper.The random seepage coefficient on the two-layer soft soil was analyzed,and the seepage model and its random distribution function were given.The groundwater flow differential equations related to the two layer soft soil structure were also established.The evaluation procedure of effect boundary on the pumping water in deep foundation pit was put forward.Moreover,with an engineering example,the probability distribution on random boundary prediction for pumping water of foundation pit was computed.

  16. A perfectly matched layer for the time-dependent wave equation in heterogeneous and layered media

    KAUST Repository

    Duru, Kenneth

    2014-01-01

    A mathematical analysis of the perfectly matched layer (PML) for the time-dependent wave equation in heterogeneous and layered media is presented. We prove the stability of the PML for discontinuous media with piecewise constant coefficients, and derive energy estimates for discontinuous media with piecewise smooth coefficients. We consider a computational setup consisting of smaller structured subdomains that are discretized using high order accurate finite difference operators for approximating spatial derivatives. The subdomains are then patched together into a global domain by a weak enforcement of interface conditions using penalties. In order to ensure the stability of the discrete PML, it is necessary to transform the interface conditions to include the auxiliary variables. In the discrete setting, the transformed interface conditions are crucial in deriving discrete energy estimates analogous to the continuous energy estimates, thus proving stability and convergence of the numerical method. Finally, we present numerical experiments demonstrating the stability of the PML in a layered medium and high order accuracy of the proposed interface conditions. © 2013 Elsevier Inc.

  17. Media as Epistemological Interfaces: McLuhan’s Medium Theory

    Directory of Open Access Journals (Sweden)

    Ana Beguš

    2014-03-01

    Full Text Available The paper presents the methodological approach of Marshall McLuhan to media research, known as the medium theory. The author initially presents the key concepts of the medium theory, including the tetrad of media effects as a tool for anticipating the cultural implications of technology, and proposes the hypothesis that McLuhan understood media as primarily epistemological interfaces. McLuhan’s methodological approach is then placed into a theoretical context, especially in comparison to other similar approaches (Benjamin, Flusser, Haraway. The last part of the paper presents the authors, building on McLuhan’s theory (Toronto School of Communication, Manovich, and the relevance of his research today.

  18. VERIFICATION OF SOCIAL IMPACT THEORY CLAIMS IN SOCIAL MEDIA CONTEXT

    Directory of Open Access Journals (Sweden)

    Imran Mir

    2012-04-01

    Full Text Available Social media explosion changed the way of communication. It affected the ways companies used to interact with their consumers. Most important it changed the way consumers used to think. Present study attempts to verify the claims and assumptions of social impact theory in the social media environment. Based on social impact theory present study examines the impa ct of number of users (NUs on the perceived credibility of user generated content (PCUGC. Furthermo re, it examines the impact of PCUGC on the consumer attitude towards the product related content embedded in UGC (ATUGC. Empirical evidence was collected from a random sample of 459 students. Results substantiate the claims and assumptions of the social impact theory in the social media context. Results show positive impact of NUs on PCUGC. Similarly, they show positive relationship between PCUGC and ATUGC

  19. Frequency Domain Modelling of Electromagnetic Wave Propagation in Layered Media

    Science.gov (United States)

    Schmidt, Felix; Lünenschloss, Peter; Mai, Juliane; Wagner, Norman; Töpfer, Hannes; Bumberger, Jan

    2016-04-01

    The amount of water in porous media such as soils and rocks is a key parameter when water resources are under investigation. Especially the quantitative spatial distribution and temporal evolution of water contents in soil formations are needed. In high frequency electromagnetic applications soil water content is quantitatively derived from the propagation behavior of electromagnetic waves along waveguides embedded in soil formations. The spatial distribution of the dielectric material properties along the waveguide can be estimated by numerical solving of the inverse problem based on the full wave forward model in time or frequency domain. However, current approaches mostly neglect or approximate the frequency dependence of the electromagnetic material properties of transfer function of the waveguide. As a first prove of concept a full two port broadband frequency domain forward model for propagation of transverse electromagnetic (TEM) waves in coaxial waveguide has been implemented. It is based on the propagation matrix approach for layered transmission line sections. Depending on the complexity of the material different models for the frequency dependent complex permittivity were applied. For the validation of the model a broadband frequency domain measurement with network analyzer technique was used. The measurement is based on a 20 cm long 50 Ohm 20/46 coaxial transmission line cell considering inhomogeneous material distributions. This approach allows (i) an increase of the waveguide calibration accuracy in comparison to conventional TDR based technique and (ii) the consideration of the broadband permittivity spectrum of the porous material. In order to systematic analyze the model, theoretical results were compared with measurements as well as 3D broadband finite element modeling of homogeneous and layered media in the coaxial transmission line cell. Defined standards (Teflon, dry glass beads, de-ionized water) were placed inside the line as the dielectric

  20. A numerical homogenization method for heterogeneous, anisotropic elastic media based on multiscale theory

    KAUST Repository

    Gao, Kai

    2015-06-05

    The development of reliable methods for upscaling fine-scale models of elastic media has long been an important topic for rock physics and applied seismology. Several effective medium theories have been developed to provide elastic parameters for materials such as finely layered media or randomly oriented or aligned fractures. In such cases, the analytic solutions for upscaled properties can be used for accurate prediction of wave propagation. However, such theories cannot be applied directly to homogenize elastic media with more complex, arbitrary spatial heterogeneity. Therefore, we have proposed a numerical homogenization algorithm based on multiscale finite-element methods for simulating elastic wave propagation in heterogeneous, anisotropic elastic media. Specifically, our method used multiscale basis functions obtained from a local linear elasticity problem with appropriately defined boundary conditions. Homogenized, effective medium parameters were then computed using these basis functions, and the approach applied a numerical discretization that was similar to the rotated staggered-grid finite-difference scheme. Comparisons of the results from our method and from conventional, analytical approaches for finely layered media showed that the homogenization reliably estimated elastic parameters for this simple geometry. Additional tests examined anisotropic models with arbitrary spatial heterogeneity in which the average size of the heterogeneities ranged from several centimeters to several meters, and the ratio between the dominant wavelength and the average size of the arbitrary heterogeneities ranged from 10 to 100. Comparisons to finite-difference simulations proved that the numerical homogenization was equally accurate for these complex cases.

  1. Mathematical analogies in physics. Thin-layer wave theory

    Directory of Open Access Journals (Sweden)

    José M. Carcione

    2014-03-01

    Full Text Available Field theory applies to elastodynamics, electromagnetism, quantum mechanics, gravitation and other similar fields of physics, where the basic equations describing the phenomenon are based on constitutive relations and balance equations. For instance, in elastodynamics, these are the stress-strain relations and the equations of momentum conservation (Euler-Newton law. In these cases, the same mathematical theory can be used, by establishing appropriate mathematical equivalences (or analogies between material properties and field variables. For instance, the wave equation and the related mathematical developments can be used to describe anelastic and electromagnetic wave propagation, and are extensively used in quantum mechanics. In this work, we obtain the mathematical analogy for the reflection/refraction (transmission problem of a thin layer embedded between dissimilar media, considering the presence of anisotropy and attenuation/viscosity in the viscoelastic case, conductivity in the electromagnetic case and a potential barrier in quantum physics (the tunnel effect. The analogy is mainly illustrated with geophysical examples of propagation of S (shear, P (compressional, TM (transverse-magnetic and TE (transverse-electric waves. The tunnel effect is obtained as a special case of viscoelastic waves at normal incidence.

  2. Herbert Marcuse's Critical Theory of the Media.

    Science.gov (United States)

    Daley, Patrick J.

    As a member of the Frankfurt School of critical theory, Herbert Marcuse believed that industrial capitalism and the bureaucratization of society stripped humans of any claims to autonomy and undermined their critical expression with a functional language. However, Marcuse did no more than point an inchoate ideological finger at the production side…

  3. Herbert Marcuse's Critical Theory of the Media.

    Science.gov (United States)

    Daley, Patrick J.

    As a member of the Frankfurt School of critical theory, Herbert Marcuse believed that industrial capitalism and the bureaucratization of society stripped humans of any claims to autonomy and undermined their critical expression with a functional language. However, Marcuse did no more than point an inchoate ideological finger at the production side…

  4. Theory of Thomson scattering in inhomogeneous media

    CERN Document Server

    Kozlowski, P M; Gericke, D O; Regan, S P; Gregori, G

    2016-01-01

    Thomson scattering of laser light is one of the most fundamental diagnostics of plasma density, temperature and magnetic fields. It relies on the assumption that the properties in the probed volume are homogeneous and constant during the probing time. On the other hand, laboratory plasmas are seldom uniform and homogeneous on the temporal and spatial dimensions over which data is collected. This is partic- ularly true for laser-produced high-energy-density matter, which often exhibits steep gradients in temperature, density and pressure, on a scale determined by the laser focus. Here, we discuss the modification of the cross section for Thomson scattering in fully-ionized media exhibiting steep spatial inhomogeneities and/or fast temporal fluctuations. We show that the predicted Thomson scattering spectra are greatly altered compared to the uniform case, and may even lead to violations of detailed balance. Therefore, careful interpretation of the spectra is necessary for spatially or temporally inhomogeneous ...

  5. Theory of Thomson scattering in inhomogeneous media

    Science.gov (United States)

    Kozlowski, P. M.; Crowley, B. J. B.; Gericke, D. O.; Regan, S. P.; Gregori, G.

    2016-04-01

    Thomson scattering of laser light is one of the most fundamental diagnostics of plasma density, temperature and magnetic fields. It relies on the assumption that the properties in the probed volume are homogeneous and constant during the probing time. On the other hand, laboratory plasmas are seldom uniform and homogeneous on the temporal and spatial dimensions over which data is collected. This is particularly true for laser-produced high-energy-density matter, which often exhibits steep gradients in temperature, density and pressure, on a scale determined by the laser focus. Here, we discuss the modification of the cross section for Thomson scattering in fully-ionized media exhibiting steep spatial inhomogeneities and/or fast temporal fluctuations. We show that the predicted Thomson scattering spectra are greatly altered compared to the uniform case, and may lead to violations of detailed balance. Therefore, careful interpretation of the spectra is necessary for spatially or temporally inhomogeneous systems.

  6. Magnetic properties of soft layer/FePt-MgO exchange coupled composite Perpendicular recording media

    Institute of Scientific and Technical Information of China (English)

    Yin Jin-Hua; Takao Suzuki; Pan Li-Qing

    2008-01-01

    The magnetic properties of exchange coupled composite(ECC)media that are composed of perpendicular magnetic recording media FePt-MgO and two kinds of soft layers have been studied by using an x-ray diffractometer,a polar Kerr magneto-optical system(PMOKE)and a vibrating sample magnetometer(VSM).The results show that ECC media can reduce the coercivities of perpendicular magnetic recording media FePt-MgO.The ECC media with granular-type soft layers have weaker exchange couplings between magnetic grains and the magnetization process,for ECC media of this kind mainly follow the Stoner-Wohlfarth model.

  7. Making sense of social media communications with chaos theory

    DEFF Research Database (Denmark)

    Gyimóthy, Szilvia; Larson, Mia

    changed the marketing landscape beyond recognition. The exponential growth of social media platforms has led to weakened marketer control (and greater consumer sovereignty) over information about organisations and their products. In this new communications paradigm (Muniz & Schau 2007), information......-making in the interactions among community members as well as marketers, by tracking how single postings are weaved and developed into complex, collective stories. The empirical data collection will restrict itself on social media of performative festivals in Scandinavia, including blogs, fansites and other interactive......, offering a few conceptual papers which adopt complexity theories to describe destination development patterns (Russel & Faulkner, 2000, 2004; Zahra & Ryan 2007). The purpose of this paper is to discuss the validity of chaos theory in the context of strategic communications, where new (social) media has...

  8. Spatial frequency domain spectroscopy of two layer media

    Science.gov (United States)

    Yudovsky, Dmitry; Durkin, Anthony J.

    2011-10-01

    Monitoring of tissue blood volume and oxygen saturation using biomedical optics techniques has the potential to inform the assessment of tissue health, healing, and dysfunction. These quantities are typically estimated from the contribution of oxyhemoglobin and deoxyhemoglobin to the absorption spectrum of the dermis. However, estimation of blood related absorption in superficial tissue such as the skin can be confounded by the strong absorption of melanin in the epidermis. Furthermore, epidermal thickness and pigmentation varies with anatomic location, race, gender, and degree of disease progression. This study describes a technique for decoupling the effect of melanin absorption in the epidermis from blood absorption in the dermis for a large range of skin types and thicknesses. An artificial neural network was used to map input optical properties to spatial frequency domain diffuse reflectance of two layer media. Then, iterative fitting was used to determine the optical properties from simulated spatial frequency domain diffuse reflectance. Additionally, an artificial neural network was trained to directly map spatial frequency domain reflectance to sets of optical properties of a two layer medium, thus bypassing the need for iteration. In both cases, the optical thickness of the epidermis and absorption and reduced scattering coefficients of the dermis were determined independently. The accuracy and efficiency of the iterative fitting approach was compared with the direct neural network inversion.

  9. On the theory of asymetrical current layer

    Science.gov (United States)

    Stanev, G.; Konstantinov, I.

    It is noted that a one-dimensional layer has previously been considered with a distribution function constructed by two Maxwellian distributions having a discontinuity in the middle of the layer. The resulting plasma sheet in this case was found to be asymmetric, but the magnetic field did not change sign. A more general self-consistent model is suggested here for current layers in a collisionless plasma which leads to a description of three-dimensional current sheets. A solution of Vlasov's equation is attempted with suitable constants of motion and adiabatic invariants. The current and the charge density are determined, and the Maxwellian equations are given in a closed form.

  10. Buckling analysis of sandwich plate using layer wise theory

    Energy Technology Data Exchange (ETDEWEB)

    Ranjbaran, Arash; Khoshravan, Mohammad Reza [University of Tabriz, Tabriz (Iran, Islamic Republic of); Kharazi, Mahsa [Sahand University of Technology, Sahand (Iran, Islamic Republic of)

    2014-07-15

    Buckling analysis of sandwich plate was investigated using layer wise method. The formulation was based on the first-order shear deformation theory, and the Rayleigh-Ritz method was used for approximating and determining the displacement field. The results obtained from layer wise theory was compared with finite element results and showed good agreement. This study demonstrated that layer wise theory could describe buckling behavior of sandwich plates with high accuracy and represents a more realistic and acceptable description of behavior of the plates with much less computational cost.

  11. McLuhan and the Cultural Theory of Media

    Directory of Open Access Journals (Sweden)

    Mark Poster

    2010-02-01

    Full Text Available Media are surely central to Western societies of the past several centuries and to the emerging global societies of the contemporary era and the future. There is a thickening, an intensification and an increasing complexity to the use of information machines, technologies that are necessary in the production, reproduction, storing and distribution of texts, images and sounds, the constituent elements of culture. The phenomenon has been termed a “media ecology,” adding a new layer to the ecologies of animal, vegetable and mineral. It behooves anyone engaged in critical discourse to take serious account of media. I argue they offer a key to understanding the process of globalization in relation to a new configuration of interaction between humans and machines.

  12. Lifshitz theory of van der Waals pressure in dissipative media

    CERN Document Server

    Zheng, Yi

    2010-01-01

    We derive a first--principles method of determining the van der Waals or Casimir pressure in a dissipative and dispersive planar multilayered system by calculating the Maxwell stress tensor in a fictitious layer of vacuum, that is eventually made to vanish, introduced in the structure. This is illustrated by calculating the van der Waals pressure in a thin film with dissipative properties embedded between two semi--infinite media.

  13. Media and migration. Layers of knowledge in Romanian written press

    Directory of Open Access Journals (Sweden)

    Ștefania Matei

    2011-11-01

    Full Text Available This paper seeks to discuss the image that the media build around the phenomenon of migration in present-day Romanian society. I rely on a content analysis of newspaper articles on migration in order to explore layers of knowledge (understood as evidence which forms the basis of the representation about an issue by identifying specific elements in each and every piece of news, such as: the current state of migration, the demographic profile of the migrant, geographical location, the orientation of the newspaper, the situation of migrants, the causes and effects of this phenomenon, and the policies implemented in the communities of origin and destination, respectively. All these elements are examined along the lines of emigration and immigration in order to reconstruct strategies of framing external migration within the journalistic discourse, and to identify the information which constitutes a reference point in shaping the attribute agenda on this topic. The discussion relies on the analysis of 473 articles in Romanian newspapers, published between 2007 and 2009, using as a sampling frame the archive of articles available on the website www.ziare.com.

  14. Generalized cable theory for neurons in complex and heterogeneous media.

    Science.gov (United States)

    Bédard, Claude; Destexhe, Alain

    2013-08-01

    Cable theory has been developed over the last decade, usually assuming that the extracellular space around membranes is a perfect resistor. However, extracellular media may display more complex electrical properties due to various phenomena, such as polarization, ionic diffusion, or capacitive effects, but their impact on cable properties is not known. In this paper, we generalize cable theory for membranes embedded in arbitrarily complex extracellular media. We outline the generalized cable equations, then consider specific cases. The simplest case is a resistive medium, in which case the equations recover the traditional cable equations. We show that for more complex media, for example, in the presence of ionic diffusion, the impact on cable properties such as voltage attenuation can be significant. We illustrate this numerically, always by comparing the generalized cable to the traditional cable. We conclude that the nature of intracellular and extracellular media may have a strong influence on cable filtering as well as on the passive integrative properties of neurons.

  15. Two parabolic equations for propagation in layered poro-elastic media.

    Science.gov (United States)

    Metzler, Adam M; Siegmann, William L; Collins, Michael D; Collis, Jon M

    2013-07-01

    Parabolic equation methods for fluid and elastic media are extended to layered poro-elastic media, including some shallow-water sediments. A previous parabolic equation solution for one model of range-independent poro-elastic media [Collins et al., J. Acoust. Soc. Am. 98, 1645-1656 (1995)] does not produce accurate solutions for environments with multiple poro-elastic layers. First, a dependent-variable formulation for parabolic equations used with elastic media is generalized to layered poro-elastic media. An improvement in accuracy is obtained using a second dependent-variable formulation that conserves dependent variables across interfaces between horizontally stratified layers. Furthermore, this formulation expresses conditions at interfaces using no depth derivatives higher than first order. This feature should aid in treating range dependence because convenient matching across interfaces is possible with discretized derivatives of first order in contrast to second order.

  16. Insights from theory and simulation on the electrical double layer.

    Science.gov (United States)

    Henderson, Douglas; Boda, Dezso

    2009-05-28

    Despite the fact that our conceptual understanding of the electrical double layer has advanced during the past few decades, the interpretation of experimental and applied work is still largely based on the venerable Poisson-Boltzmann theory of Gouy, Chapman and Stern. This is understandable since this theory is simple and analytic. However, it is not very accurate because the atomic/molecular nature of the ions/solvent and their correlations are ignored. Simulation and some theoretical studies by ourselves and others that have advanced our understanding are discussed. These studies show that the GCS theory predicts a narrow double layer with monotonic profiles. This is not correct. The double layer is wider, and there can be substantial layering that would be even more pronounced if explicit solvent molecules are considered. For many years, experimental studies of the double layer have been directed to the use of electrochemistry as an analytical tool. This is acceptable for analytic chemistry studies. However, the understanding of electrochemical reactions that typically occur at the electrode surface, where simulation and theory indicate that the GCS theory can have substantial errors, requires modern approaches. New, fundamental experimental studies that would lead to deeper insights using more novel systems would be desirable. Further, biophysics is an interesting field. Recent studies of the selectivity of ion channels and of the adsorption of ions in a binding sites of a protein have shown that the linearized GCS theory has substantial errors.

  17. Optical characterization of two-layered turbid media for non-invasive, absolute oximetry in cerebral and extracerebral tissue.

    Directory of Open Access Journals (Sweden)

    Bertan Hallacoglu

    Full Text Available We introduce a multi-distance, frequency-domain, near-infrared spectroscopy (NIRS method to measure the optical coefficients of two-layered media and the thickness of the top layer from diffuse reflectance measurements. This method features a direct solution based on diffusion theory and an inversion procedure based on the Levenberg-Marquardt algorithm. We have validated our method through Monte Carlo simulations, experiments on tissue-like phantoms, and measurements on the forehead of three human subjects. The Monte Carlo simulations and phantom measurements have shown that, in ideal two-layered samples, our method accurately recovers the top layer thickness (L, the absorption coefficient (µ a and the reduced scattering coefficient (µ' s of both layers with deviations that are typically less than 10% for all parameters. Our method is aimed at absolute measurements of hemoglobin concentration and saturation in cerebral and extracerebral tissue of adult human subjects, where the top layer (layer 1 represents extracerebral tissue (scalp, skull, dura mater, subarachnoid space, etc. and the bottom layer (layer 2 represents cerebral tissue. Human subject measurements have shown a significantly greater total hemoglobin concentration in cerebral tissue (82±14 µM with respect to extracerebral tissue (30±7 µM. By contrast, there was no significant difference between the hemoglobin saturation measured in cerebral tissue (56%±10% and extracerebral tissue (62%±6%. To our knowledge, this is the first time that an inversion procedure in the frequency domain with six unknown parameters with no other prior knowledge is used for the retrieval of the optical coefficients and top layer thickness with high accuracy on two-layered media. Our absolute measurements of cerebral hemoglobin concentration and saturation are based on the discrimination of extracerebral and cerebral tissue layers, and they can enhance the impact of NIRS for cerebral hemodynamics and

  18. A micropolar mixture theory of multi-component porous media

    Institute of Scientific and Technical Information of China (English)

    Lu HUANG; Cheng-gang ZHAO

    2009-01-01

    A mixture theory is developed for multi-component micropolar porous media with a combination of the hybrid mixture theory and the micropolar continuum theory.The system is modeled as multi-component micropolar elastic solids saturated with multicomponent micropolar viscous fluids. Balance equations are given through the mixture theory. Constitutive equations are developed based on the second law of thermodynamics and constitutive assumptions. Taking account of compressibility of solid phases,the volume fraction of fluid as an independent state variable is introduced in the free energy function,and the dynamic compatibility condition is obtained to restrict the change of pressure difference on the solid-fluid interface. The constructed constitutive equations are used to close the field equations. The linear field equations are obtained using a linearization procedure,and the micropolar thermo-hydro-mechanical component transport model is established. This model can be applied to practical problems,such as contaminant,drug,and pesticide transport. When the proposed model is supposed to be porous media,and both fluid and solid are single-component,it will almost agree with Eringen's model.

  19. Spatial bandwidth enlargement and field enhancement of shear horizontal waves in finite graded piezoelectric layered media

    KAUST Repository

    Xu, Yanlong

    2015-09-01

    Shear horizontal (SH) wave propagation in finite graded piezoelectric layered media is investigated by transfer matrix method. Different from the previous studies on SH wave propagation in completely periodic layered media, calculations on band structure and transmission in this paper show that the graded layered media possess very large band gaps. Harmonic wave simulation by finite element method (FEM) confirms that the reason of bandwidth enlargement is that waves within the band gap ranges are spatially enhanced and stopped by the corresponding graded units. The study suggests that the graded structure possesses the property of manipulating elastic waves spatially, which shows potential applications in strengthening energy trapping and harvesting. © 2015.

  20. Making sense of social media communications with chaos theory

    DEFF Research Database (Denmark)

    Gyimóthy, Szilvia; Larson, Mia

    -organising, as the pattern of behaviour in the system evolves or emerges from the local interaction and adjustments between the agents. Instead of channelled flow of information, the nodes of this network transmit information in all directions simultaneously. Our goal is model the patterns of sense-making......Introduction Social scientists have long been inspired by chaos theory to describe the complexities of organisational change (Wheatley, 1993; Burnes, 2004), entrepreneurship (Steyaert, 2007) or urban development (Batty & Xie, 1999) arguing that firms or regions are dynamic and unpredictable systems......, offering a few conceptual papers which adopt complexity theories to describe destination development patterns (Russel & Faulkner, 2000, 2004; Zahra & Ryan 2007). The purpose of this paper is to discuss the validity of chaos theory in the context of strategic communications, where new (social) media has...

  1. Converted-wave Seismology in Anisotropic Media Revisited, Part I: Basic Theory

    Institute of Scientific and Technical Information of China (English)

    XiangyangLi; JianxinYuan

    2005-01-01

    We have developed new basic theories for calculating the conversion point and the travel time of the P-SV converted wave (C-wave) in anisotropic, inhomogeneous media. This enables the use of conventional procedures such as semblance analysis, Dix-type model building and Kirchhoff summation, to implement anisotropic processing, and makes anisotropic processing affordable. Here we present these new developments in two parts: basic theory and application to velocity analysis and parameter estimation. This part deals with the basic theory, including both conversion-point calculation and moveout analysis.Existing equations for calculating the PS-wave (C-wave) conversion point in layered media with vertical transverse isotropy (VTI) are strictly limited to offsets about half the reflector depth (an offset-depth ratio, x/z, of 0.5), and those for calculating the C-wave traveltimes are limited to offsets equal to the reflector depth (x/z=1.0). In contrast, the new equations for calculating the conversion-point extend into offsets about three-times the reflector depth (x/z=3.0), those for calculating the C-wave traveltimes extend into offsets twice the reflector depth (x/z=2.0). With the improved accuracy, the equations can help in C-wave data processing and parameter estimation in anisotropic, inhomogeneous media.

  2. New Theories on Boundary Layer Transition and Turbulence Formation

    Directory of Open Access Journals (Sweden)

    Chaoqun Liu

    2012-01-01

    Full Text Available This paper is a short review of our recent DNS work on physics of late boundary layer transition and turbulence. Based on our DNS observation, we propose a new theory on boundary layer transition, which has five steps, that is, receptivity, linear instability, large vortex structure formation, small length scale generation, loss of symmetry and randomization to turbulence. For turbulence generation and sustenance, the classical theory, described with Richardson's energy cascade and Kolmogorov length scale, is not observed by our DNS. We proposed a new theory on turbulence generation that all small length scales are generated by “shear layer instability” through multiple level ejections and sweeps and consequent multiple level positive and negative spikes, but not by “vortex breakdown.” We believe “shear layer instability” is the “mother of turbulence.” The energy transferring from large vortices to small vortices is carried out by multiple level sweeps, but does not follow Kolmogorov's theory that large vortices pass energy to small ones through vortex stretch and breakdown. The loss of symmetry starts from the second level ring cycle in the middle of the flow field and spreads to the bottom of the boundary layer and then the whole flow field.

  3. A general theory of wave interactions in layered flows

    CERN Document Server

    Guha, Anirban

    2016-01-01

    Using kinematics, we propose a theory of non-modal interactions between the interfaces of a 2D, inviscid, multi-layered fluid system. Specifically, a $3$-interface problem with kinematic and geometric symmetry is explored. Repetitive, extremely short bursts of very high wave growth/decay-rates are observed in the parameter ranges where normal-mode theory predicts stability. The underlying dynamical system predicts chaotic outcomes for some initial conditions. For realistic multi-layered flows, such instabilities of finite amplitude may alter the mean flow to a noisy, unpredictable state.

  4. Van der Waals interaction torque and force between dielectrically anisotropic layered media

    CERN Document Server

    Lu, Bing-Sui

    2016-01-01

    We analyse the van der Waals interaction for a pair of dielectrically anisotropic plane-layered media interacting across a dielectrically isotropic medium. We investigate the van der Waals torque and force for the following cases: (i) a pair of single anisotropic layers, (ii) a single anisotropic layer interacting with a multilayered slab consisting of alternating anisotropic and isotropic layers, and (iii) a pair of multilayered slabs each consisting of alternating anisotropic and isotropic layers, looking at the cases where the optical axes lie parallel and/or perpendicular to the plane of the layers. For the first case, the optical axes of the oppositely facing anisotropic layers of the two interacting slabs generally have an angular mismatch, and within each multilayered slab the optical axes may either be the same, or undergo constant angular increments across the anisotropic layers. In particular, we examine how the behaviors of the van der Waals torque and force can be "tuned" by adjusting the layer th...

  5. Nature, theory and modelling of geophysical convective planetary boundary layers

    Science.gov (United States)

    Zilitinkevich, Sergej

    2015-04-01

    Geophysical convective planetary boundary layers (CPBLs) are still poorly reproduced in oceanographic, hydrological and meteorological models. Besides the mean flow and usual shear-generated turbulence, CPBLs involve two types of motion disregarded in conventional theories: 'anarchy turbulence' comprised of the buoyancy-driven plumes, merging to form larger plumes instead of breaking down, as postulated in conventional theory (Zilitinkevich, 1973), large-scale organised structures fed by the potential energy of unstable stratification through inverse energy transfer in convective turbulence (and performing non-local transports irrespective of mean gradients of transporting properties). C-PBLs are strongly mixed and go on growing as long as the boundary layer remains unstable. Penetration of the mixed layer into the weakly turbulent, stably stratified free flow causes turbulent transports through the CPBL outer boundary. The proposed theory, taking into account the above listed features of CPBL, is based on the following recent developments: prognostic CPBL-depth equation in combination with diagnostic algorithm for turbulence fluxes at the CPBL inner and outer boundaries (Zilitinkevich, 1991, 2012, 2013; Zilitinkevich et al., 2006, 2012), deterministic model of self-organised convective structures combined with statistical turbulence-closure model of turbulence in the CPBL core (Zilitinkevich, 2013). It is demonstrated that the overall vertical transports are performed mostly by turbulence in the surface layer and entrainment layer (at the CPBL inner and outer boundaries) and mostly by organised structures in the CPBL core (Hellsten and Zilitinkevich, 2013). Principal difference between structural and turbulent mixing plays an important role in a number of practical problems: transport and dispersion of admixtures, microphysics of fogs and clouds, etc. The surface-layer turbulence in atmospheric and marine CPBLs is strongly enhanced by the velocity shears in

  6. The impact of electronic media violence: scientific theory and research.

    Science.gov (United States)

    Huesmann, L Rowell

    2007-12-01

    Since the early 1960s, research evidence has been accumulating that suggests that exposure to violence in television, movies, video games, cell phones, and on the Internet increases the risk of violent behavior on the viewer's part, just as growing up in an environment filled with real violence increases the risk of them behaving violently. In the current review this research evidence is critically assessed and the psychological theory that explains why exposure to violence has detrimental effects for both the short and long-term is elaborated. Finally the size of the "media violence effect" is compared with some other well-known threats to society to estimate how important a threat it should be considered.

  7. High-resolution imaging and inversion of 3D GPR data for layered media

    Science.gov (United States)

    Slob, Evert

    2013-04-01

    Ground penetrating radar is increasingly being used to provide quantitative information of layered structures. For application in civil engineering these can be roads, highway pavements, airport runways, bridges, tunnels, or buildings. Monitoring is important for the management and safety of these structures. Standard imaging uses a modeled wavefield extrapolator to image the data and the quality of the image depends heavily on the quality of the modeled extrapolator. Usually, data inversion is implemented by minimizing a cost function involving the measured data and the modeled data. The model is modified such that data computed from the model fits to the measured data. The data itself is not used, except as a measure of the model data fit. A recently developed alternative method is to use results from inverse scattering theory to first construct an image while all multiple reflections are simultaneously eliminated from the data. This image can be constructed from surface reflection data if the data allows separating the subsurface reflection response from the down going emitted field. For 3D waves in a layered medium this requires knowledge of all horizontal electric and magnetic field components. If the data is properly sampled the solution is unique. In layered media the plane wave decomposition allows computing the image for each angle of incidence separately as a function of image time that is equal to the one-way intercept time. Once the image is constructed for all available angles of incidence a simple matrix inversion leads to the desired electric permittivity and magnetic permeability values in each layer. Finally these values provide interval velocities that can be used to convert image time to depth and the inverse problem is solved. The theory requires infinite bandwidth frequency domain data, which is equivalent to measuring the true impulse response. This is not possible in practice and numerical results show that data with finite bandwidths can be

  8. Boundary Layer Flows in Porous Media with Lateral Mass Flux

    DEFF Research Database (Denmark)

    Nemati, H; H, Bararnia; Noori, F;

    2015-01-01

    Solutions for free convection boundary layers on a heated vertical plate with lateral mass flux embedded in a saturated porous medium are presented using the Homotopy Analysis Method and Shooting Numerical Method. Homotopy Analysis Method yields an analytic solution in the form of a rapidly...

  9. Understanding work-related social media use: An extension of theory of planned behavior.

    NARCIS (Netherlands)

    van Zoonen, W.; Verhoeven, J.W.M.; Elving, W.J.L.

    2014-01-01

    This study examines the motives of employees to engage in work related social media use - i.e. the use of personal social media accounts to communicate about work-related issues. The theory of planned behavior (TPB) was used to explain this behavior. Because social media can enable users to express

  10. Understanding work-related social media use: An extension of theory of planned behavior.

    NARCIS (Netherlands)

    van Zoonen, W.; Verhoeven, J.W.M.; Elving, W.J.L.

    2014-01-01

    This study examines the motives of employees to engage in work related social media use - i.e. the use of personal social media accounts to communicate about work-related issues. The theory of planned behavior (TPB) was used to explain this behavior. Because social media can enable users to express

  11. Influence of buoyant media on particle layer dynamics in microfiltration membranes

    Energy Technology Data Exchange (ETDEWEB)

    Aryal, R.K.; Vigneswaran, S.; Kandasamy, J. [University of Technology Sydney, Sydney, NSW (Australia). Faculty of Engineering & Information Technology

    2010-07-01

    This study forms a part of the physical study of the membrane bioreactor in presence of buoyancy media. Kaolin clay suspension with buoyancy media (anthracite) was used as a suspension and the particle layer development on membrane surface with evolution of time was studied. Presence of buoyancy media reduced the pressure development by almost two folds compared to in absence of the media. The particles deposition on membrane surface was size selective. The mean particle diameter (0.45 {mu} m) deposited on the membrane surface remained almost similar in presence of the media after 7 hrs run where as in its absence the mean diameter finer particles deposition occurred at the beginning followed by coarser particles.

  12. Influence of buoyant media on particle layer dynamics in microfiltration membranes.

    Science.gov (United States)

    Aryal, R K; Vigneswaran, S; Kandasamy, Jaya

    2010-01-01

    This study forms a part of the physical study of the membrane bioreactor in presence of buoyancy media. Kaolin clay suspension with buoyancy media (anthracite) was used as a suspension and the particle layer development on membrane surface with evolution of time was studied. Presence of buoyancy media reduced the pressure development by almost two folds compared to in absence of the media. The particles deposition on membrane surface was size selective. The mean particle diameter (0.45 mum) deposited on the membrane surface remained almost similar in presence of the media after 7 hrs run where as in its absence the mean diameter finer particles deposition occurred at the beginning followed by coarser particles.

  13. Mass Communication as Political Rhetoric: A Critique of Representation and Commodity Theories of Mass Media Language.

    Science.gov (United States)

    Shaver, Paul M.

    1995-01-01

    Suggests that contemporary rhetorical theory and research can use important insights into the nature of mass media language that representation and commodity theories cannot incorporate. Suggests that, by recognizing the rhetorical aspects of media language, scholars can legitimize the research and the dialogue that are required for the…

  14. Experimental investigation on rainfall infiltration and solute transport in layered porous and fractured media

    Institute of Scientific and Technical Information of China (English)

    WANG Hui-fang; WANG Ming-yu

    2012-01-01

    Layered structures with upper porous and lower fractured media are widely distributed in the world.An experimental investigation on rainfall infiltration and solute transport in such layered structures can provide the necessary foundation for effectively preventing and forecasting water bursting in mines,controlling contamination of mine water,and accomplishing ecological restoration of mining areas.A typical physical model of the layered structures with porous and fractured media was created in this study.Then rainfall infiltration experiments were conducted after salt solution was sprayed on the surface of the layered structure.The volumetric water content and concentration of chlorine ions at different specified positions along the profile of the experiment system were measured in real-time.The experimental results showed that the lower fractured media,with a considerably higher permeability than that of the upper porous media,had significant effects on preventing water infiltration.Moreover,although the porous media were homogeneous statistically in the whole domain,spatial variations in the features of effluent concentrations with regards to time,or so called breakthrough curves,at various sampling points located at the horizontal plane in the porous media near the porous-fractured interface were observed,indicating the diversity of solute transport at small scales.Furthermore,the breakthrough curves of the outflow at the bottom,located beneath the underlying fractured rock,were able to capture and integrate features of the breakthrough curves of both the upper porous and fractured media,which exhibited multiple peaks,while the peak values were reduced one by one with time.

  15. Looking to the future of new media in health marketing: deriving propositions based on traditional theories.

    Science.gov (United States)

    Della, Lindsay J; Eroglu, Dogan; Bernhardt, Jay M; Edgerton, Erin; Nall, Janice

    2008-01-01

    Market trend data show that the media marketplace continues to rapidly evolve. Recent research shows that substantial portions of the U.S. media population are "new media" users. Today, more than ever before, media consumers are exposed to multiple media at the same point in time, encouraged to participate in media content generation, and challenged to learn, access, and use the new media that are continually entering the market. These media trends have strong implications for how consumers of health information access, process, and retain health-related knowledge. In this article we review traditional information processing models and theories of interpersonal and mass media access and consumption. We make several theory-based propositions for how traditional information processing and media consumption concepts will function as new media usage continues to increase. These propositions are supported by new media usage data from the Centers for Disease Control and Prevention's entry into the new media market (e.g., podcasting, virtual events, blogging, and webinars). Based on these propositions, we conclude by presenting both opportunities and challenges that public health communicators and marketers will face in the future.

  16. FOLDER: A numerical tool to simulate the development of structures in layered media

    Science.gov (United States)

    Adamuszek, Marta; Dabrowski, Marcin; Schmid, Daniel W.

    2015-04-01

    FOLDER is a numerical toolbox for modelling deformation in layered media during layer parallel shortening or extension in two dimensions. FOLDER builds on MILAMIN [1], a finite element method based mechanical solver, with a range of utilities included from the MUTILS package [2]. Numerical mesh is generated using the Triangle software [3]. The toolbox includes features that allow for: 1) designing complex structures such as multi-layer stacks, 2) accurately simulating large-strain deformation of linear and non-linear viscous materials, 3) post-processing of various physical fields such as velocity (total and perturbing), rate of deformation, finite strain, stress, deviatoric stress, pressure, apparent viscosity. FOLDER is designed to ensure maximum flexibility to configure model geometry, define material parameters, specify range of numerical parameters in simulations and choose the plotting options. FOLDER is an open source MATLAB application and comes with a user friendly graphical interface. The toolbox additionally comprises an educational application that illustrates various analytical solutions of growth rates calculated for the cases of folding and necking of a single layer with interfaces perturbed with a single sinusoidal waveform. We further derive two novel analytical expressions for the growth rate in the cases of folding and necking of a linear viscous layer embedded in a linear viscous medium of a finite thickness. We use FOLDER to test the accuracy of single-layer folding simulations using various 1) spatial and temporal resolutions, 2) time integration schemes, and 3) iterative algorithms for non-linear materials. The accuracy of the numerical results is quantified by: 1) comparing them to analytical solution, if available, or 2) running convergence tests. As a result, we provide a map of the most optimal choice of grid size, time step, and number of iterations to keep the results of the numerical simulations below a given error for a given time

  17. Students' Misconceptions about the Ozone Layer and the Effect of Internet-Based Media on It

    Science.gov (United States)

    Gungordu, Nahide; Yalcin-Celik, Ayse; Kilic, Ziya

    2017-01-01

    In this study, students' misconceptions about the ozone layer were investigated, looking specifically at the effect internet-based media has on the formation of these misconceptions. Quantitative and qualitative research approaches were used to perform the research. As part of the quantitative portion of the research, the descriptive survey…

  18. Magnetotelluric inversion for anisotropic conductivities in layered media

    Science.gov (United States)

    Pek, Josef; Santos, Fernando A. M.

    2006-10-01

    Electrical anisotropy in the Earth's crust and upper mantle has recently gained attention as a significant linking factor between electrical models and underlying structural and tectonic patterns. This interest has also motivated new methodological studies into the modelling and inversion for electrically anisotropic structures. We present an algorithm for the inversion of magnetotelluric data over layered anisotropic conductors which is a straightforward extension of the standard Occam 1-D inversion to anisotropic models. Owing to the essential limitation of magnetotellurics to resolve the complete conductivity tensor, we formulate the inversion for azimuthal anisotropy only. We treat the non-linear inverse problem as a multi-criterion minimization of the structure complexity, data misfit and anisotropy. To constrain the structure complexity, we employ the standard roughness penalty as well as non-quadratic penalties of the total variation and gradient support type that produce more focused model sections and thus conform better to the idea about sharp, non-diffuse boundaries of anisotropic structures in the Earth. Application of the anisotropy penalty is crucial for suppressing spurious anisotropy in the inverse models. We use a 2-D extension of the heuristic L-curve method to estimate the quasi-optimal penalty weights. With two non-linear iteration solvers, specifically the reweighted conjugate gradient method and the lagged diffusivity iteration, we can arrive at the minimum of the target functional, for one selected pair of regularization weights, typically after a few tens of iteration steps. To demonstrate the inverse solution, we present two simple yet not completely trivial synthetic examples, the first one based on data generated by a model with two anisotropic layers with discordant strikes, and the other showing possible misinterpretations in case a 1-D inversion with anisotropy is formally applied to data produced by simple 2-D block structures. Field

  19. Superconductivity in layered binary silicides: A density functional theory study

    Science.gov (United States)

    Flores-Livas, José A.; Debord, Régis; Botti, Silvana; San Miguel, Alfonso; Pailhès, Stéphane; Marques, Miguel A. L.

    2011-11-01

    A class of metal disilicides (of the form XSi2, where X is a divalent metal) crystallizes in the EuGe2 structure, formed by hexagonal corrugated silicon planes intercalated with metal atoms. These compounds are superconducting like other layered superconductors, such as MgB2. Moreover, their properties can be easily tuned either by external pressure or by negative chemical pressure (i.e., by changing the metal), which makes disilicides an ideal testbed to study superconductivity in layered systems. In view of this, we present an extensive density functional theory study of the electronic and phonon band structures as well as the electron-phonon interaction of metal disilicides. Our results explain the variation of the superconducting transition temperature with pressure and the species of the intercalating atom, and allow us to predict superconductivity for compounds not yet synthesized belonging to this family.

  20. In vivo spatial frequency domain spectroscopy of two layer media

    Science.gov (United States)

    Yudovsky, Dmitry; Nguyen, John Quan M.; Durkin, Anthony J.

    2012-10-01

    Monitoring of tissue blood volume and local oxygen saturation can inform the assessment of tissue health, healing, and dysfunction. These quantities can be estimated from the contribution of oxyhemoglobin and deoxyhemoglobin to the absorption spectrum of the dermis. However, estimation of blood related absorption in skin can be confounded by the strong absorption of melanin in the epidermis and epidermal thickness and pigmentation varies with anatomic location, race, gender, and degree of disease progression. Therefore, a method is desired that decouples the effect of melanin absorption in the epidermis from blood absorption in the dermis for a large range of skin types and thicknesses. A previously developed inverse method based on a neural network forward model was applied to simulated spatial frequency domain reflectance of skin for multiple wavelengths in the near infrared. It is demonstrated that the optical thickness of the epidermis and absorption and reduced scattering coefficients of the dermis can be determined independently and with minimal coupling. Then, the same inverse method was applied to reflectance measurements from a tissue simulating phantom and in vivo human skin. Oxygen saturation and total hemoglobin concentrations were estimated from the volar forearms of weakly and strongly pigmented subjects using a standard homogeneous model and the present two layer model.

  1. Efficient computation of periodic and nonperiodic Green`s functions in layered media using the MPIE

    Energy Technology Data Exchange (ETDEWEB)

    Wilton, D.R.; Jackson, D.R.; Champagne, N.J.

    1998-03-27

    The mixed potential integral equation (MPIE) formulation is convenient for problems involving layered media because potential quantities involve low order singularities, in comparison to field quantities. For nonperiodic problems, the associated Green`s potentials involve spectral integrals of the Sommerfeld type, in the periodic case, discrete sums over sampled values of the same spectra are required. When source and observation points are in the same or in adjacent layers, the convergence of both representations is enhanced by isolating the direct and quasi-static image contributions associated with the nearby layers. In the periodic case, the convergence of direct and image contributions may be rapidly accelerated by means of the Ewadd method.

  2. Real-time convolution method for generating light diffusion profiles of layered turbid media.

    Science.gov (United States)

    Kim, Hoe-Min; Ko, Kwang Hee; Lee, Kwan H

    2011-06-01

    In this paper we present a technique to obtain a diffusion profile of layered turbid media in real time by using the quasi fast Hankel transform (QFHT) and the latest graphics processing unit technique. We apply the QFHT to convolve the diffusion profiles of each layer so as to dramatically reduce the time for the convolution step while maintaining the accuracy. In addition, we also introduce an accelerated technique to generate individual discrete diffusion profiles for each layer through parallel processing. The proposed method is 2 orders of magnitude faster than the existing method, and we validate its efficiency by comparing it with Monte Carlo simulation and another relevant methods.

  3. Explaining the use of text-based communication media: an examination of three theories of media use.

    Science.gov (United States)

    Park, Namkee; Chung, Jae Eun; Lee, Seungyoon

    2012-07-01

    The present study examined the factors associated with individuals' use of three different text-based communication media: e-mail, cell-phone texting, and Facebook Wall postings. Three theoretical perspectives, including media richness theory, uses and gratifications, and perceived network effects, were examined. Using data from a survey of college students (N=280), the study found that the theoretical constructs from these theories play different roles when applied to different technologies. The results suggest that a simultaneous consideration of technological attributes, users' motivations, and social circumstances in which users select and use the technology is useful for fully understanding the dynamics of the selection and the use of a given technology.

  4. Invariant imbedding theory of wave propagation in arbitrarily inhomogeneous stratified bi-isotropic media

    CERN Document Server

    Kim, Seulong

    2016-01-01

    Bi-isotropic media, which include isotropic chiral media and Tellegen media as special cases, are the most general form of linear isotropic media where the electric displacement and the magnetic induction are related to both the electric field and the magnetic intensity. In inhomogeneous bi-isotropic media, electromagnetic waves of two different polarizations are coupled to each other. In this paper, we develop a generalized version of the invariant imbedding method for the study of wave propagation in arbitrarily-inhomogeneous stratified bi-isotropic media, which can be used to solve the coupled wave propagation problem accurately and efficiently. We verify the validity and usefulness of the method by applying it to several examples, including the wave propagation in a uniform chiral slab, the surface wave excitation in a bilayer system made of a layer of Tellegen medium and a metal layer, and the mode conversion of transverse electromagnetic waves into longitudinal plasma oscillations in inhomogeneous Telle...

  5. Efficient and accurate computation of electric field dyadic Green's function in layered media

    CERN Document Server

    Cho, Min Hyung

    2016-01-01

    Concise and explicit formulas for dyadic Green's functions, representing the electric and magnetic fields due to a dipole source placed in layered media, are derived in this paper. First, the electric and magnetic fields in the spectral domain for the half space are expressed using Fresnel reflection and transmission coefficients. Each component of electric field in the spectral domain constitutes the spectral Green's function in layered media. The Green's function in the spatial domain is then recovered involving Sommerfeld integrals for each component in the spectral domain. By using Bessel identities, the number of Sommerfeld integrals are reduced, resulting in much simpler and more efficient formulas for numerical implementation compared with previous results. This approach is extended to the three-layer Green's function. In addition, the singular part of the Green's function is naturally separated out so that integral equation methods developed for free space Green's functions can be used with minimal mo...

  6. Integral-Operator Analysis of Layered Media and Integrated Microstrip Configurations.

    Science.gov (United States)

    Yuan, Yi.

    This dissertation presents a rigorous full-wave integral operator formulation for electromagnetic interactions among microstrip configurations in the layered environment, and a comprehensive study on one of the most essential elements in microwave and millimeter-wave integrated circuits (MMIC's), the microstrip transmission lines. Broad electromagnetic phenomena associated with microstrip transmission lines, including their propagation spectrum, dispersion characteristics, coupling effects, current distributions, characteristic impedances, losses and leakage and/or radiation properties are investigated via the integral equation approach. First, dyadic Green's functions are developed for layered media with both dielectric and magnetic contrast. Based on the Green's functions, an electric field integral equation (EFIE) description for general microstrip circuits is developed, and then applied to microstrip transmission lines. The complete propagation-mode spectrum of microstrip line is identified and an excitation and coupling theory is developed. Propagation modes on isolated and coupled microstrip transmission lines are studied in details. Numerical solutions to the EFIE's are implemented by Galerkin's method of moments. Chebyshev polynomials with square-root edge factors are utilized as basis functions. An accurate circuit modeling of the non-TEM microstrip line structure is described and a full -wave analysis for the characteristic impedance is developed. Also, a EFIE-based full-wave perturbation theory for N coupled microstrip transmission lines is presented. An experimental verification is carried out and the theoretical and experimental results are in a good agreement. Much effort is made in this thesis in developing a unified, consistent, complex integral equation-formulation which correctly handles the problem of general lossy and leaky microstrip lines. In discussions of the bound waveguiding modes and the non-spectral radiative leaky modes, the propagation

  7. Computing the scattering properties of participating media using Lorenz-Mie theory

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Christensen, Niels Jørgen; Jensen, Henrik Wann

    2007-01-01

    This paper introduces a theoretical model for computing the scattering properties of participating media and translucent materials. The model takes as input a description of the components of a medium and computes all the parameters necessary to render it. These parameters are the extinction...... and scattering coefficients, the phase function, and the index of refraction. Our theory is based on a robust generalization of the Lorenz-Mie theory. Previous models using Lorenz-Mie theory have been limited to non-absorbing media with spherical particles such as paints and clouds. Our generalized theory...... is capable of handling both absorbing host media and non-spherical particles, which significantly extends the classes of media and materials that can be modeled. We use the theory to compute optical properties for different types of ice and ocean water, and we derive a novel appearance model for milk...

  8. An eigen theory of static electromagnetic field for anisotropic media

    Institute of Scientific and Technical Information of China (English)

    Shao-hua GUO

    2009-01-01

    Static electromagnetic fields are studied based on standard spaces of the physical presentation,and the modal equations of static electromagnetic fields for anisotropic media are derived. By introducing a new set of first-order potential functions,several novel theoretical results are obtained. It is found that,for isotropic media,electric or magnetic potentials are scalar; while for anisotropic media,they are vectors. Magnitude and direction of the vector potentials are related to the anisotropic subspaces. Based on these results,we discuss the laws of static electromagnetic fields for anisotropic media.

  9. Folder: a MATLAB-based tool for modelling deformation in layered media subject to layer parallel shortening or extension

    Science.gov (United States)

    Adamuszek, Marta; Dabrowski, Marcin; Schmid, Daniel W.

    2016-04-01

    We present Folder, a numerical tool to simulate and analyse the structure development in mechanically layered media during the layer parallel shortening or extension. Folder includes a graphical user interface that allows for easy designing of complex geometrical models, defining material parameters (including linear and non-linear rheology), and specifying type and amount of deformation. It also includes a range of features that facilitate the visualization and examination of various relevant quantities e.g. velocities, stress, rate of deformation, pressure, and finite strain. Folder contains a separate application, which illustrates analytical solutions of growth rate spectra for layer parallel shortening and extension of a single viscous layer. In the study, we also demonstrate a Folder application, where the role of confinement on the growth rate spectrum and the fold shape evolution during the deformation of a single layer subject to the layer parallel shortening is presented. In the case of the linear viscous materials used for the layer and matrix, the close wall proximity leads to a decrease of the growth rate values. The decrease is more pronounced for the larger wavelengths than for the smaller wavelengths. The growth rate reduction is greater when the walls are set closer to the layer. The presence of the close confinement can also affect the wavelength selection process and significantly shift the position of the dominant wavelength. The influence of the wall proximity on the growth rate spectrum for the case of non-linear viscous materials used for the layer and/or matrix is very different as compared to the linear viscous case. We observe a multiple maxima in the growth rate spectrum. The number of the growth rate maxima, their value and the position strongly depend on the closeness of the confinement. The maximum growth rate value for a selected range of layer-wall distances is much larger than in the case when the confinement effect is not taken

  10. Local Structure Analysis and Interface Layer Effect of Phase-Change Recording Material Using Actual Media

    Science.gov (United States)

    Nakai, Tsukasa; Yoshiki, Masahiko; Satoh, Yasuhiro; Ashida, Sumio

    2008-07-01

    The influences of the interface layer on crystal structure, the local atomic arrangement, and the electronic and chemical structure of a GeBiTe (GBT) phase-change recording material have been investigated using X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), and hard X-ray photoelectron spectroscopy (HX-PES) methods using actual rewritable high-speed HD DVD media without special sample processing. XRD results showed that the crystal structure of laser-crystallized GBT alloy in the actual HD DVD media is the same as that of GeSbTe (GST) alloy, which has a NaCl-type structure. No differences between samples with and without interface layers were found. The lattice constant of GBT is larger than that of GST. Bi increases the lattice constant of GST with respect to the Bi substitution ratio of Sb. According to HX-PES, the DOS of in the recording film amorphous state with an interface layer is closer to that of the crystalline state than the recording film without an interface layer. From XAFS results, clear differences between amorphous (Amo.) and crystalline states (Cry.) were observed. The interatomic distance of amorphous recording material is independent of the existence of an interface layer. On the other hand, the coordination number varied slightly due to the presence of the interface layer. Therefore, the electronic state of the recording layer changes because of the interface layer, although the local structure changes only slightly except for the coordination number. Combining these results, we conclude that the interface layer changes the electronic state of the recording layer and promotes crystallization, but only affects the local structure of the atomic arrangement slightly.

  11. Exposure to Media and Theory-of-Mind Development in Preschoolers

    Science.gov (United States)

    Mar, Raymond A.; Tackett, Jennifer L.; Moore, Chris

    2010-01-01

    Exposure to different forms of narrative media may influence children's development of theory-of-mind. Because engagement with fictional narratives provides one with information about the social world, and possibly draws upon theory-of-mind processes during comprehension, exposure to storybooks, movies, and television may influence theory-of-mind…

  12. Exposure to Media and Theory-of-Mind Development in Preschoolers

    Science.gov (United States)

    Mar, Raymond A.; Tackett, Jennifer L.; Moore, Chris

    2010-01-01

    Exposure to different forms of narrative media may influence children's development of theory-of-mind. Because engagement with fictional narratives provides one with information about the social world, and possibly draws upon theory-of-mind processes during comprehension, exposure to storybooks, movies, and television may influence theory-of-mind…

  13. Media Analysis as Critical Reflexology in Exploring Adult Learning Theories

    Science.gov (United States)

    Hutchins, Holly M.; Bierema, Laura

    2013-01-01

    Examining media artifacts as a learning method has received little attention in human resource development (HRD) despite it being a predominate form of information and influence in popular culture. As Giroux (2002) opines, media functions as a form of public pedagogy by offering situations and contexts through which viewers can vicariously…

  14. Stiffness matrix method with improved efficiency for elastic wave propagation in layered anisotropic media

    Science.gov (United States)

    Tan, Eng Leong

    2005-12-01

    This paper presents the recursive algorithm of stiffness matrix method with improved efficiency for computing the total and surface stiffness matrices for a general multilayered anisotropic media. Based on the eigensolutions commonly available for analysis of such media, the recursive algorithm deals with eigen-submatrices directly and bypasses all intermediate layer stiffness submatrices. The improved algorithm obviates the need to compute certain inverse of the original scheme and makes the stiffness matrix recursion more robust. In situation where transfer matrix is numerically stable and easily accessible, an improved recursive algorithm is also given directly in terms of transfer submatrices without involving their explicit inverse.

  15. Reconstruction of cylindrically layered media using an iterative algorithm with a stable solution

    Institute of Scientific and Technical Information of China (English)

    CHENG Ji-zhen; NIU Zuo-yuan; CHENG Chong-hu

    2007-01-01

    The reconstruction of cylindrically layered media is investigated in this article. The inverse problem is modeled using a source-type integral equation with a series of cylindrical waves as incidences, and a conventional Born iterative procedure is modified for solving the integral equation. In the modified iterative procedure, a conventional single-point approximation for the calculation of the field inside media is replaced by a multi-points approximation to improve the numerical stability of its solution. Numerical simulations for different permittivity distributions are demon- strated in terms of artificial scattering data with the procedure. The result shows that the procedure enjoys both accuracy and stability in the numerical computation.

  16. Popular Culture and Critical Media Literacy in Adult Education: Theory and Practice

    Science.gov (United States)

    Tisdell, Elizabeth J.

    2007-01-01

    This chapter introduces the volume, provides an overview of the theory and literature on popular culture and critical media literacy in education, and discusses ways to use popular culture in adult education.

  17. Social Learning Theory in the Age of Social Media: Implications for Educational Practitioners

    Science.gov (United States)

    Deaton, Shannon

    2015-01-01

    Following the research of Albert Bandura, the advent of social media has changed the platform for social interaction and human experience. Educators have a unique opportunity to apply the concepts of Bandura's Social Learning Theory toward enhanced student engagement and learning in a social media context. This article synthesizes current research…

  18. Examining the Use of Theory within Educational Technology and Media Research

    Science.gov (United States)

    Bulfin, Scott; Henderson, Michael; Johnson, Nicola

    2013-01-01

    Academic research in the areas of educational technology and media is often portrayed to be limited in terms of its use of theory. This short paper reports on data collected from a survey of 462 "research active" academic researchers working in the broad area of educational technology and educational media. The paper explores their use…

  19. What Critical Media Studies Should Not Take from Actor-Network Theory

    NARCIS (Netherlands)

    Teurlings, J.; Spöhrer, M.; Ochsner, B.

    2017-01-01

    While supportive towards a certain rapprochement between media studies and Actor-Network Theory (ANT) this chapter identi es three main characteristics of the Latourian enterprise that critical media studies should avoid if it wants to remain its critical edge: 1. a methodological descriptivism that

  20. Social Learning Theory in the Age of Social Media: Implications for Educational Practitioners

    Science.gov (United States)

    Deaton, Shannon

    2015-01-01

    Following the research of Albert Bandura, the advent of social media has changed the platform for social interaction and human experience. Educators have a unique opportunity to apply the concepts of Bandura's Social Learning Theory toward enhanced student engagement and learning in a social media context. This article synthesizes current research…

  1. Japanese Communication Research: The Emphasis on Macro Theories of Media in an "Information-Based" Environment.

    Science.gov (United States)

    Cooper, Roger

    1997-01-01

    Most mass media research in Japan focuses on the influence of mass communication on society as a whole; these "macro" theories typically employ traditional social science techniques. Reasons for this situation are examined, as well as how media researchers outside of Japan might learn from the Japanese perspectives about the role and function of…

  2. Japanese Communication Research: The Emphasis on Macro Theories of Media in an "Information-Based" Environment.

    Science.gov (United States)

    Cooper, Roger

    1997-01-01

    Most mass media research in Japan focuses on the influence of mass communication on society as a whole; these "macro" theories typically employ traditional social science techniques. Reasons for this situation are examined, as well as how media researchers outside of Japan might learn from the Japanese perspectives about the role and…

  3. Polymedia: Towards a new theory of digital media in interpersonal communication

    OpenAIRE

    Madianou, M.; Miller, D

    2013-01-01

    This article develops a new theory of polymedia in order to understand the consequences of digital media in the context of interpersonal communication. Drawing on illustrative examples from a comparative ethnography of Filipino and Caribbean transnational families, the article develops the contours of a theory of polymedia. We demonstrate how users avail themselves of new media as a communicative environment of affordances rather than as a catalogue of ever proliferating but discrete technolo...

  4. An empirical theory for gravitationally unstable flow in porous media

    NARCIS (Netherlands)

    Farajzadeh, R.; Meulenbroek, B.J.; Daniel, D.; Riaz, A.; Bruining, J.

    2013-01-01

    In this paper, we follow a similar procedure as proposed by Koval (SPE J 3(2):145–154, 1963) to analytically model CO2 transfer between the overriding carbon dioxide layer and the brine layer below it. We show that a very thin diffusive layer on top separates the interface from a gravitationally

  5. Analytical Investigation Of Pigments, Ground Layer And Media Of Cartonnage Fragments From Greek Roman Period

    Science.gov (United States)

    Afifi, Hala. A. M.

    Some cartonnage fragments from Hawara, Fayoum Excavation were examined to identify pigments, media and grounds. It belonged to the Greek-Roman period. They were studied by X-ray diffraction (XRD), Energy dispersive X ray analysis (EDS) equipped with Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). These techniques were used to identify the composition and morphology of grounds, nature of pigments and media used in cartonnage fragments. The coarse ground layer was composed of calcite and traces of quartz. The fine ground layer used under the pigments directly was composed of calcite only. Carbon black was used as black pigment while lead oxide as red pigment, showing the influence of Roman and Greek pigments on Egyptian art in these later periods. Blue colorant was identified as cuprorivaite and yellow pigment was goethite. Animal glue was used in the four pigments as medium colored.

  6. Bit Patterned Magnetic Recording: Theory, Media Fabrication, and Recording Performance

    OpenAIRE

    Albrecht, Thomas R.; Arora, Hitesh; Ayanoor-Vitikkate, Vipin; Beaujour, Jean-Marc; Bedau, Daniel; Berman, David; Bogdanov, Alexei L.; Chapuis, Yves-Andre; Cushen, Julia; Dobisz, Elizabeth E.; Doerk, Gregory; Gao, He; Grobis, Michael; Gurney, Bruce; Hanson, Weldon

    2015-01-01

    Bit Patterned Media (BPM) for magnetic recording provide a route to densities $>1 Tb/in^2$ and circumvents many of the challenges associated with conventional granular media technology. Instead of recording a bit on an ensemble of random grains, BPM uses an array of lithographically defined isolated magnetic islands, each of which stores one bit. Fabrication of BPM is viewed as the greatest challenge for its commercialization. In this article we describe a BPM fabrication method which combine...

  7. Efficient CFIE-MOM Analysis of 3-D PEC Scatterers in Layered Media

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Jørgensen, E.; Meincke, Peter;

    2002-01-01

    This paper presents an efficient technique for analysis of arbitrary closed perfectly conducting (PEC) scatterers in layered media. The technique is based on a method of moments (MoM) solution of the combined field integral equation (CFIE). The high efficiency is obtained by employing an accurate...... expansion of the multilayer dyadic Green's function along with a higher order hierarchical discretization scheme and a rapidly converging iterative solver with preconditioner....

  8. Modern media in the light of fine art as a school subject based on the constructive theory

    OpenAIRE

    2015-01-01

    The introduction of the article presents a terminological definition of media in general and a terminological definition of media within Fine Art as a school subject. It also presents the influence of media on Fine Art as a school subject. Furthermore, the author discusses the uses of modern media in Fine Art, selecting media and the suitability of individual media according to set artistic tasks. The main part of the article presents the constructive theory of teaching with its characteristi...

  9. Putting Social Media in Its Place: A Curatorial Theory for Media’s Noisy Social Worlds

    OpenAIRE

    Mary L. Gray

    2015-01-01

    The quest to make sense of media’s impact—what it does to us—dominates communication theories and popular discourse about media. But the impulse to collar, cultivate, domesticate, or measure the impact of media on individuals and society can have pernicious effects, too. This essay calls for a set of new analytical models to account for media as messy instantiations of social interaction transforming before our very eyes. We need to shift from a media effects paradigm that narrowly focuses on...

  10. Learning theory and its application to the use of social media in medical education.

    Science.gov (United States)

    Flynn, Leslie; Jalali, Alireza; Moreau, Katherine A

    2015-10-01

    There is rapidly increasing pressure to employ social media in medical education, but a review of the literature demonstrates that its value and role are uncertain. To determine if medical educators have a conceptual framework that informs their use of social media and whether this framework can be mapped to learning theory. Thirty-six participants engaged in an iterative, consensus building process that identified their conceptual framework and determined if it aligned with one or more learning theories. The results show that the use of social media by the participants could be traced to two dominant theories-Connectivism and Constructivism. They also suggest that many medical educators may not be fully informed of these theories. Medical educators' use of social media can be traced to learning theories, but these theories may not be explicitly utilised in instructional design. It is recommended that formal education (faculty development) around learning theory would further enhance the use of social media in medical education. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  11. Atmospheric boundary layers in storms: advanced theory and modelling applications

    Directory of Open Access Journals (Sweden)

    S. S. Zilitinkevich

    2005-01-01

    Full Text Available Turbulent planetary boundary layers (PBLs control the exchange processes between the atmosphere and the ocean/land. The key problems of PBL physics are to determine the PBL height, the momentum, energy and matter fluxes at the surface and the mean wind and scalar profiles throughout the layer in a range of regimes from stable and neutral to convective. Until present, the PBLs typical of stormy weather were always considered as neutrally stratified. Recent works have disclosed that such PBLs are in fact very strongly affected by the static stability of the free atmosphere and must be treated as factually stable (we call this type of the PBL "conventionally neutral" in contract to the "truly neutral" PBLs developed against the neutrally stratified free flow. It is common knowledge that basic features of PBLs exhibit a noticeable dependence on the free-flow static stability and baroclinicity. However, the concern of the traditional theory of neural and stable PBLs was almost without exception the barotropic nocturnal PBL, which develops at mid latitudes during a few hours in the night, on the background of a neutral or slightly stable residual layer. The latter separates this type of the PBL from the free atmosphere. It is not surprising that the nature of turbulence in such regimes is basically local and does not depend on the properties of the free atmosphere. Alternatively, long-lived neutral (in fact only conditionally neutral or stable PBLs, which have much more time to grow up, are placed immediately below the stably stratified free flow. Under these conditions, the turbulent transports of momentum and scalars even in the surface layer - far away from the PBL outer boundary - depend on the free-flow Brunt-Väisälä frequency, N. Furthermore, integral measures of the long-lived PBLs (their depths and the resistance law functions depend on N and also on the baroclinic shear, S. In the traditional PBL models both non-local parameters N and S

  12. Atmospheric boundary layers in storms: advanced theory and modelling applications

    Science.gov (United States)

    Zilitinkevich, S. S.; Esau, I. N.; Baklanov, A.

    2005-03-01

    Turbulent planetary boundary layers (PBLs) control the exchange processes between the atmosphere and the ocean/land. The key problems of PBL physics are to determine the PBL height, the momentum, energy and matter fluxes at the surface and the mean wind and scalar profiles throughout the layer in a range of regimes from stable and neutral to convective. Until present, the PBLs typical of stormy weather were always considered as neutrally stratified. Recent works have disclosed that such PBLs are in fact very strongly affected by the static stability of the free atmosphere and must be treated as factually stable (we call this type of the PBL "conventionally neutral" in contract to the "truly neutral" PBLs developed against the neutrally stratified free flow). It is common knowledge that basic features of PBLs exhibit a noticeable dependence on the free-flow static stability and baroclinicity. However, the concern of the traditional theory of neural and stable PBLs was almost without exception the barotropic nocturnal PBL, which develops at mid latitudes during a few hours in the night, on the background of a neutral or slightly stable residual layer. The latter separates this type of the PBL from the free atmosphere. It is not surprising that the nature of turbulence in such regimes is basically local and does not depend on the properties of the free atmosphere. Alternatively, long-lived neutral (in fact only conditionally neutral) or stable PBLs, which have much more time to grow up, are placed immediately below the stably stratified free flow. Under these conditions, the turbulent transports of momentum and scalars even in the surface layer - far away from the PBL outer boundary - depend on the free-flow Brunt-Väisälä frequency, N. Furthermore, integral measures of the long-lived PBLs (their depths and the resistance law functions) depend on N and also on the baroclinic shear, S. In the traditional PBL models both non-local parameters N and S were overlooked

  13. The Management of Media Organizations from Theory to Practice

    Directory of Open Access Journals (Sweden)

    Ph. D. Cristina Andreescu (Manolache

    2009-12-01

    Full Text Available Media organizations have become a barometer in the development of a society. The way these organizations are managed depends on the context they can be placed in. Media organizations can be assimilated with a social and economic context. I attempted to emphasize the importance of good management that takes into account the basic principles and which can be integrated into a media organization. Leadership should be concerned with combining the specifics of management with those of human nature.The need for management is real. As it is the interdependence between the media organization and an efficient management. Despite their shortcomings, today’s managers are able to manage a newspaper, a radio or a television station. They can be divided into three categories, namely: managers of a media organization, having no knowledge of management; managers having the necessary training but unaware of how to implement management rules and finally, managers with very good training but lacking interest, who let things run by themselves.

  14. Putting Social Media in Its Place: A Curatorial Theory for Media’s Noisy Social Worlds

    Directory of Open Access Journals (Sweden)

    Mary L. Gray

    2015-04-01

    Full Text Available The quest to make sense of media’s impact—what it does to us—dominates communication theories and popular discourse about media. But the impulse to collar, cultivate, domesticate, or measure the impact of media on individuals and society can have pernicious effects, too. This essay calls for a set of new analytical models to account for media as messy instantiations of social interaction transforming before our very eyes. We need to shift from a media effects paradigm that narrowly focuses on the brightest signals of social media use and turn to what I will call here a curatorial theory of social media. This approach, inspired by research from several founding editors of Social Media + Society, focuses on media’s cultural work and myriad manifestations—from its technologies to the discourses that flow through and from them. Let us attend to the more elusive, noisy cultural and social forces that bring some aspects of media sharply into focus while obscuring others. And, above all, let us pay attention to the curatorial reworking of media that happens in particular places—nations, towns, bodies.

  15. Theorising Media, Power and Politics in Discourse Theory and Framing Studies

    DEFF Research Database (Denmark)

    Dindler, Camilla; Roslyng, Mette Marie

    The development of digital media has profound consequences for social and political interaction and, therefore, a new radical interactivity also influences the way in which media can be theorised and analysed? (Couldry, 2012, p. 2). As pointed out by Hall (2006) and others, media discourse may...... either contribute to or challenge the current status quo. Likewise, media framing studies indicate that the media may play an independent political role in terms of raising, shaping and morally judging issues of civic relevance (Entman, 2004). Framing and discourse theory have overlapping as well...... believe that this is a both timely and necessary endeavour considering the radical interactivity that characterizes mediated political communication today. Conceptualisations of power and politics will be addressed in order to compare and examine these two approaches to political media analysis...

  16. Analytical investigations of the magnetotelluric directionality estimation in 1-D anisotropic layered media

    Science.gov (United States)

    Okazaki, T.; Oshiman, N.; Yoshimura, R.

    2016-11-01

    Inferring geoelectric dimensionality (1D, 2D or 3D) and directionality (strike directions) from the impedance tensor is a basic procedure in magnetotelluric data processing. Given that electrical anisotropy is increasingly recognized in observations, it is valuable to understand the imprint of anisotropy in these analyses. In this paper, we analytically investigate the estimation of strike directions based on rotational invariants in 1D anisotropic layered media. We first show that if anisotropy axes are identical in all anisotropic layers, the estimated strike coincides with that direction. We then derive an analytical formula of the strike angle at long periods for general anisotropic layers with an isotropic basement. This formula shows a clear physical interpretation that the strike angle points where the conductance integrated along depth takes a maximum value.

  17. Folder: A numerical tool to simulate the development of structures in layered media

    Science.gov (United States)

    Adamuszek, Marta; Dabrowski, Marcin; Schmid, Daniel W.

    2016-03-01

    We present Folder, a numerical toolbox for modelling deformation in layered media subject to layer parallel shortening or extension in two dimensions. The toolbox includes a range of features that ensure maximum flexibility to configure model geometry, define material parameters, specify numerical parameters, and choose the plotting options. Folder builds on an efficient finite element method model and implements state of the art iterative and time integration schemes. We describe the basic Folder features and present several case studies of single and multilayer stacks subject to layer parallel shortening and extension. Folder additionally comprises an application that illustrates various analytical solutions of growth rates calculated for the cases of layer parallel shortening and extension of a single layer with interfaces perturbed with a single sinusoidal waveform. We further derive two novel analytical expressions for the growth rate in the cases of layer parallel shortening and extension of a linear viscous layer embedded in a linear viscous medium of a finite thickness. These solutions help understand mechanical instabilities in layered rocks and provide a unique opportunity for benchmarking of numerical codes. We demonstrate how Folder can be used for benchmarking of numerical codes. We test the accuracy of single-layer folding simulations using various 1) spatial and temporal resolutions, 2) iterative algorithms for non-linear materials, and 3) time integration schemes. The accuracy of the numerical results is quantified by: 1) comparing them to analytical solutions, if available, or 2) running convergence tests. As a result, we provide a map of the most optimal choice of grid size, time step, and number of iterations to keep the results of the numerical simulations below a given error for a given time integration scheme. Folder is an open source MATLAB application and comes with a user-friendly graphical interface. Folder is suitable for both educational

  18. Guided wave propagation in single and double layer hollow cylinders embedded in infinite media.

    Science.gov (United States)

    Jia, Hua; Jing, Mu; Joseph, L Rose

    2011-02-01

    Millions of miles of pipes are being used for the transportation, distribution, and local use of petroleum products, gas, water, and chemicals. Most of the pipes are buried in soil, leading to the significance of the study on the subject of guided wave propagation in pipes with soil influence. Previous investigations of ultrasonic guided wave propagation in an elastic hollow cylinder and in an elastic hollow cylinder coated with a viscoelastic material have led to the development of inspection techniques for bare and coated pipes. However, the lack of investigation on guided wave propagation in hollow cylinders embedded in infinite media like soil has hindered the development of pipe inspection methods. Therefore the influence of infinite media on wave propagation is explored in this paper. Dispersion curves and wave structures of both axisymmetric and nonaxisymmetric wave modes are developed. Due to the importance of the convergence of numerical calculations, the requirements of thickness and element number of the finite soil layer between hollow cylinder and infinite element layer are discussed, and an optimal combination is obtained in this paper. Wave structures are used for the mode identification in the non-monotonic region caused by the viscoelastic properties of coating and infinite media.

  19. Perpendicular Magnetic Anisotropy in FePt Patterned Media Employing a CrV Seed Layer

    Directory of Open Access Journals (Sweden)

    Chun Dong

    2011-01-01

    Full Text Available Abstract A thin FePt film was deposited onto a CrV seed layer at 400°C and showed a high coercivity (~3,400 Oe and high magnetization (900–1,000 emu/cm3 characteristic of L10 phase. However, the magnetic properties of patterned media fabricated from the film stack were degraded due to the Ar-ion bombardment. We employed a deposition-last process, in which FePt film deposited at room temperature underwent lift-off and post-annealing processes, to avoid the exposure of FePt to Ar plasma. A patterned medium with 100-nm nano-columns showed an out-of-plane coercivity fivefold larger than its in-plane counterpart and a remanent magnetization comparable to saturation magnetization in the out-of-plane direction, indicating a high perpendicular anisotropy. These results demonstrate the high perpendicular anisotropy in FePt patterned media using a Cr-based compound seed layer for the first time and suggest that ultra-high-density magnetic recording media can be achieved using this optimized top-down approach.

  20. Perpendicular Magnetic Anisotropy in FePt Patterned Media Employing a CrV Seed Layer.

    Science.gov (United States)

    Kim, Hyunsu; Noh, Jin-Seo; Roh, Jong Wook; Chun, Dong Won; Kim, Sungman; Jung, Sang Hyun; Kang, Ho Kwan; Jeong, Won Yong; Lee, Wooyoung

    2011-12-01

    A thin FePt film was deposited onto a CrV seed layer at 400°C and showed a high coercivity (~3,400 Oe) and high magnetization (900-1,000 emu/cm(3)) characteristic of L 10 phase. However, the magnetic properties of patterned media fabricated from the film stack were degraded due to the Ar-ion bombardment. We employed a deposition-last process, in which FePt film deposited at room temperature underwent lift-off and post-annealing processes, to avoid the exposure of FePt to Ar plasma. A patterned medium with 100-nm nano-columns showed an out-of-plane coercivity fivefold larger than its in-plane counterpart and a remanent magnetization comparable to saturation magnetization in the out-of-plane direction, indicating a high perpendicular anisotropy. These results demonstrate the high perpendicular anisotropy in FePt patterned media using a Cr-based compound seed layer for the first time and suggest that ultra-high-density magnetic recording media can be achieved using this optimized top-down approach.

  1. The New Media Art Design Talk about the Development of Marxist Artistic Production Theory

    Institute of Scientific and Technical Information of China (English)

    付翔辰

    2013-01-01

    Art production is Marx from the perspective of economics to study and put forward a special concept, is a kind of u-nique art theory research findings. The current rapid development in science and technology and the medium of art production fol owed changed and rich, so the derivative production of new media art and design. Therefore, art production theory thus gain deeper research, demand is also the practice of modern art theory.

  2. Semianalytical Solutions of Radioactive or Reactive Tracer Transport in Layered Fractured Media

    Energy Technology Data Exchange (ETDEWEB)

    G.J. Moridis; G. S. Bodvarsson

    2001-10-01

    In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive tracers (solutes or colloids) through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the matrix account for (a) diffusion, (b) surface diffusion (for solutes only), (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first order chemical reactions. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Additionally, the colloid transport equations account for straining and velocity adjustments related to the colloidal size. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity. {sup 239}Pu colloid transport problems in multilayered systems indicate significant colloid accumulations at straining interfaces but much faster transport of the colloid than the corresponding strongly sorbing solute species.

  3. Semianalytical Solutions of Radioactive or Reactive Transport in Variably-Fractured Layered Media: 1. Solutes

    Energy Technology Data Exchange (ETDEWEB)

    George J. Moridis

    2001-10-01

    In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive solute tracers through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the non-flowing matrix account for (a) diffusion, (b) surface diffusion, (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first-order chemical reactions. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity.

  4. Semianalytical solutions of radioactive or reactive transport invariably-fractured layered media: 1. Solutes

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George J.

    2001-10-10

    In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive solute tracers through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the non-flowing matrix account for (a) diffusion, (b) surface diffusion, (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first-order chemical reactions. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity.

  5. Semianalytical solutions of radioactive or reactive tracer transport in layered fractured media

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, G.J.; Bodvarsson, G.S.

    2001-10-10

    In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive tracers (solutes or colloids) through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the matrix account for (a) diffusion, (b) surface diffusion (for solutes only), (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first order chemical reactions. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Additionally, the colloid transport equations account for straining and velocity adjustments related to the colloidal size. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity. {sup 239}Pu colloid transport problems in multilayered systems indicate significant colloid accumulations at straining interfaces but much faster transport of the colloid than the corresponding strongly sorbing solute species.

  6. Steam and air co-injection in removing residual TCE in unsaturated layered sandy porous media.

    Science.gov (United States)

    Peng, Sheng; Wang, Ning; Chen, Jiajun

    2013-10-01

    Steam and air co-injection is a promising technique for volatile and semi-volatile organic contaminant remediation in heterogeneous porous media. In this study, removal of trichloroethene (TCE) with steam-air co-injection was investigated through a series of 2D sandbox experiments with different layered sand structures, and through numerical simulations. The results show that a layered structure with coarse sand, in which steam and air convection are relatively rapid, resulted in a higher removal rate and a larger removal ratio than those observed in an experiment using finer sand; however, the difference was not significant, and the removal ratios from three experiments ranged from 85% to 94%. Slight downward movement of TCE was observed for Experiment 1 (TCE initially in a fine sand zone encased in a coarse sand), while no such movement was observed for Experiment 2 (TCE initially in two fine sand layers encased in a coarse sand) or 3 (TCE initially in a silty sand zone encased in a coarse sand). Simulations show accumulation of TCE at the interface of the layered sands, which indicates a capillary barrier effect in restraining the downward movement of TCE. This effect is illustrated further by a numerical experiment with homogeneous coarse sand, in which continuous downward TCE movement to the bottom of the sandbox was simulated. Another numerical experiment with higher water saturation was also conducted. The results illustrate a complicated influence of water saturation on TCE removal in a layered sand structure.

  7. Determination of Effective Thermal Conductivity For Real Porous Media Using Fractal Theory

    Institute of Scientific and Technical Information of China (English)

    ChenYongping; ShiMingheng

    1999-01-01

    In this paper,using fractal theory,the geometric structure of real soil was described with ist section view and section particle area fractal dimension d of porous media was counted.The volumetric solid content and the relation between volumetric solid content and porous media particle arrangements as well as measure scale were obtainted.A heat conduction model was established and the effective thermal conductivity of real soil based on the volumetric solid content was calculated.

  8. Porous Media and Immersed Boundary Hybrid-Modelling for Simulating Flow in Stone Cover-Layers

    DEFF Research Database (Denmark)

    Jensen, Bjarne; Liu, Xiaofeng; Christensen, Erik Damgaard

    2017-01-01

    In this paper we present a new numerical modelling approach for coastal and marine applications where a porous media conceptual model was combined with a free surface volume-of-fluid (VOF) model and an immersed boundary method (IBM). The immersed boundary model covers the method of describing a s....... In this paper, the model is applied to investigate two practical cases in terms of a cover layer of stones on a flat bed under oscillatory flow at different packing densities, and a rock toe structure at a breakwater....

  9. 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

    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....... 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...

  10. Electro-chemical aspects of IPMCs within the framework of the theory of porous media

    Science.gov (United States)

    Leichsenring, P.; Serdas, S.; Wallmersperger, T.; Bluhm, J.; Schröder, J.

    2017-04-01

    Ionomeric polymer–metal composites (IPMCs) consist of an ionomer with bound anionic groups and mobile counterions. They are plated with noble impermeable metal cover layers. By application of an electric voltage, a transport of the mobile ions towards the respective electrode occurs. Due to local electrostatic and ionic forces, a local deformation of the IPMC can be observed. Therefore IPMCs are promising candidates for electrochemical transducers. In the present research, the chemo-electro-mechanical behavior of IPMCs is described within the framework of the theory of porous media. First, the field equations are derived with respect to the second law of thermodynamics. Second, a reduced set of equations for the chemo-electric behavior is formulated and discretized by applying the finite element method. In the numerical investigations a parametric study of the time and space dependent behavior is carried out in order to quantify the influence of different material compositions. Based on this study, the characteristic response of IPMC to the application of an electric voltage can be predicted. Concluding, the obtained computational framework is an excellent tool for the design of electrochemical transducers.

  11. Pseudo-hcp nonmagnetic intermediate layer for granular media with high perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Atsushi [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Saito, Shin [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Itagaki, Norikazu [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Takahashi, Migaku [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2008-01-07

    Materials with the hexagonal close-packed structure (hcp) and the face-centred-cubic structure with stacking faults (pseudo-hcp) are examined for the nonmagnetic intermediate layer (NMIL) in order to suppress variant growth of magnetic grains for granular-type perpendicular recording media. Judging from the analysis of the epitaxial growth of Co-based magnetic grains, it has been found that a lattice misfit between NMIL and magnetic grain of less than 6% and a spreading coefficient of wettability of magnetic grain on NMIL of greater than 0.3 J m{sup -3} are required for the recording layer to have high perpendicular magnetic anisotropy energy. (fast track communication)

  12. Gelled propellant flow: Boundary layer theory for power-law fluids in a converging planar channel

    Science.gov (United States)

    Kraynik, Andrew M.; Geller, A. S.; Glick, J. H.

    1989-10-01

    A boundary layer theory for the flow of power-law fluids in a converging planar channel has been developed. This theory suggests a Reynolds number for such flows, and following numerical integration, a boundary layer thickness. This boundary layer thickness has been used in the generation of a finite element mesh for the finite element code FIDAP. FIDAP was then used to simulate the flow of power-law fluids through a converging channel. Comparison of the analytic and finite element results shows the two to be in very good agreement in regions where entrance and exit effects (not considered in the boundary layer theory) can be neglected.

  13. When Ants Move Mountains: Uncovering a Media Theory of Human Agency

    Directory of Open Access Journals (Sweden)

    Patricia W. Elliott

    2016-05-01

    Full Text Available Just as Smythe argued communication was the “blindspot of western Marxism,” western communication and media theorizing itself suffers a blind spot, when it places media power in the hands of dictators and captains of industry as if no others might put pen to paper and change history. Meanwhile, theoretical explorations of how media praxis might be understood and employed for emancipation – not subjugation – emerged through the experiences of people in the Global South and Indigenous communities. This article examines and contrasts the theoretical silos, seeking moments of cross-over and synergy between static, top-down conceptualizations of Western mass media theory, and the more people-powered media praxis of colonized people seeking liberation. Building on the literature of differing experiences, the author draws a framework to encompass the full spectrum of media power. Here scholars, policy planners, and media practitioners alike may find common ground from which to recognize and support grassroots media producers as agents of meaningful social change.

  14. Broadband ultraviolet-visible optical property measurement in layered turbid media

    Science.gov (United States)

    Wang, Quanzeng; Le, Du; Ramella-Roman, Jessica; Pfefer, Joshua

    2012-01-01

    The ability to accurately measure layered biological tissue optical properties (OPs) may improve understanding of spectroscopic device performance and facilitate early cancer detection. Towards these goals, we have performed theoretical and experimental evaluations of an approach for broadband measurement of absorption and reduced scattering coefficients at ultraviolet-visible wavelengths. Our technique is based on neural network (NN) inverse models trained with diffuse reflectance data from condensed Monte Carlo simulations. Experimental measurements were performed from 350 to 600 nm with a fiber-optic-based reflectance spectroscopy system. Two-layer phantoms incorporating OPs relevant to normal and dysplastic mucosal tissue and superficial layer thicknesses of 0.22 and 0.44 mm were used to assess prediction accuracy. Results showed mean OP estimation errors of 19% from the theoretical analysis and 27% from experiments. Two-step NN modeling and nonlinear spectral fitting approaches helped improve prediction accuracy. While limitations and challenges remain, the results of this study indicate that our technique can provide moderately accurate estimates of OPs in layered turbid media. PMID:22741070

  15. Practical Theories of Teaching, Media, and Classroom Management.

    Science.gov (United States)

    Swartz, James D.

    This paper examines teachers' practical theories of teaching and ways in which individual teachers participate in a social solidarity, based on Richard Rorty's idea of solidarity as clinging to one's own ethnocentrism to understand differences between right and wrong, good and bad. Social solidarity is seen as holding people together, defining…

  16. A generalized Debye source approach to electromagnetic scattering in layered media

    Energy Technology Data Exchange (ETDEWEB)

    O’Neil, Michael, E-mail: oneil@cims.nyu.edu [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States)

    2014-01-15

    The standard solution to time-harmonic electromagnetic scattering problems in homogeneous layered media relies on the use of the electric field dyadic Green's function. However, for small values of the governing angular frequency ω, evaluation of the electric field using this Green's function exhibits numerical instability. In this short note, we provide an alternative approach which is immune from this low-frequency breakdown as ω → 0. Our approach is based on the generalized Debye source representation of Maxwell fields. Using this formulation, the electric and magnetic fields gracefully decouple in the static limit, a behavior similar to that of the classical Lorenz-Debye-Mie representation of Maxwell fields in spherical geometries. We derive extensions of both the generalized Deybe source and Lorenz-Debye-Mie representations to planar geometries, as well as provide equations for the solution of scattering from a perfectly conducting half-space and in layered media using a Sommerfeld-like approach. These formulas are stable as ω tends to zero, and offer alternatives to the electric field dyadic Green's function.

  17. Optical measurements of absorption changes in two-layered diffusive media

    Energy Technology Data Exchange (ETDEWEB)

    Fabbri, Francesco [Department of Biomedical Engineering, Bioengineering Center, Tufts University, 4 Colby Street, Medford, MA 02155 (United States); Sassaroli, Angelo [Department of Biomedical Engineering, Bioengineering Center, Tufts University, 4 Colby Street, Medford, MA 02155 (United States); Henry, Michael E [McLean Hospital and Department of Psychiatry, Harvard Medical School, 115 Mill Street, Belmont, MA 02478 (United States); Fantini, Sergio [Department of Biomedical Engineering, Bioengineering Center, Tufts University, 4 Colby Street, Medford, MA 02155 (United States)

    2004-04-07

    We have used Monte Carlo simulations for a two-layered diffusive medium to investigate the effect of a superficial layer on the measurement of absorption variations from optical diffuse reflectance data processed by using: (a) a multidistance, frequency-domain method based on diffusion theory for a semi-infinite homogeneous medium; (b) a differential-pathlength-factor method based on a modified Lambert-Beer law for a homogeneous medium and (c) a two-distance, partial-pathlength method based on a modified Lambert-Beer law for a two-layered medium. Methods (a) and (b) lead to a single value for the absorption variation, whereas method (c) yields absorption variations for each layer. In the simulations, the optical coefficients of the medium were representative of those of biological tissue in the near-infrared. The thickness of the first layer was in the range 0.3-1.4 cm, and the source-detector distances were in the range 1-5 cm, which is typical of near-infrared diffuse reflectance measurements in tissue. The simulations have shown that (1) method (a) is mostly sensitive to absorption changes in the underlying layer, provided that the thickness of the superficial layer is {approx}0.6 cm or less; (2) method (b) is significantly affected by absorption changes in the superficial layer and (3) method (c) yields the absorption changes for both layers with a relatively good accuracy of {approx}4% for the superficial layer and {approx}10% for the underlying layer (provided that the absorption changes are less than 20-30% of the baseline value). We have applied all three methods of data analysis to near-infrared data collected on the forehead of a human subject during electroconvulsive therapy. Our results suggest that the multidistance method (a) and the two-distance partial-pathlength method (c) may better decouple the contributions to the optical signals that originate in deeper tissue (brain) from those that originate in more superficial tissue layers.

  18. The Impact of Electronic Media Violence: Scientific Theory and Research

    OpenAIRE

    HUESMANN, L. ROWELL

    2007-01-01

    Since the early 1960s research evidence has been accumulating that suggests that exposure to violence in television, movies, video games, cell phones, and on the internet increases the risk of violent behavior on the viewer’s part just as growing up in an environment filled with real violence increases the risk of them behaving violently. In the current review this research evidence is critically assessed, and the psychological theory that explains why exposure to violence has detrimental eff...

  19. Reconstruction of Vertical Profile of Permittivity of Layered Media which is Probed Using Vertical Differential Antenna

    Science.gov (United States)

    Pochanin, Gennadiy P.; Poyedinchuk, Anatoliy Y.; Varianytsia-Roshchupkina, Liudmyla A.; Pochanina, Iryna Ye.

    2016-04-01

    Results of this research are intended to use at GPR investigations of layered media (for example, at roads' inspection) for the processing of collected data and reconstruction of dependence of permittivity on the depth. Recently, an antenna system with a vertical differential configuration of receiving module (Patent UA81652) for GPR was suggested and developed The main advantage of the differential antennas in comparison with bistatic antennas is a high electromagnetic decoupling between the transmitting and receiving modules. The new vertical differential configuration has an additional advantage because it allows collecting GPR data reflected by layered media without any losses of information about these layers [1] and, potentially, it is a more accurate instrument for the layers thickness measurements [2]. The developed antenna system is tested in practice with the GPR at asphalt thickness measurements [3] and shown an accuracy which is better than 0.5 cm. Since this antenna system is good for sounding from above the surface (air coupled technique), the mobile laboratory was equipped with the developed GPR [3]. In order to process big set of GPR data that collected during probing at long routes of the roads, for the data processing it was tested new algorithm of the inverse problem solution. It uses a fast algorithm for calculation of electromagnetic wave diffraction by non-uniform anisotropic layers [4]. The algorithm is based on constructing a special case solution to the Riccati equation for the Cauchy problem and enables a qualitative description of the wave diffraction by the electromagnetic structure of the type within a unitary framework. At this stage as initial data we used synthetic GPR data that were obtained as results of the FDTD simulation of the problem of UWB electromagnetic impulse diffraction on layered media. Differential and bistatic antenna configurations were tested at several different profiles of permittivity. Meanings of permittivity of

  20. [The theory of germ layers: the debatable aspects].

    Science.gov (United States)

    Dondua, A K

    1994-01-01

    Data on early embryonic development of animals provided the basis for the following conclusions. In most (if not in all) species, germinal layers are not primitive structures recapitulating the initial organs of ancestral forms. The initial cell differentiation in the embryo is not directly associated with gastrulation, and the common concept of a fundamental relationship between germinal layer formation and cell differentiation is erroneous. Specification of cell types during early development and morphogenetic movements during gastrulation are relatively autonomous processes controlled by different genetic systems. The formation of germinal layers during individual development of different multicellular animals can be understood taking into account that segregation of cell layers is an essential element of epithelial morphogenesis. Movement of cells and cell layers during gastrulation is a specific manifestation of a general morphogenetic principle.

  1. A general theory of two-wave mixing in nonlinear media

    DEFF Research Database (Denmark)

    Chi, Mingjun; Huignard, Jean-Pierre; Petersen, Paul Michael

    2009-01-01

    A general theory of two-wave mixing in nonlinear media is presented. Assuming a gain (or absorption) grating and a refractive index grating are generated because of the nonlinear process in a nonlinear medium, the coupled-wave equations of two-wave mixing are derived based on the Maxwell’s wave e...

  2. Using Popular Media and a Collaborative Approach to Teaching Grounded Theory Research Methods

    Science.gov (United States)

    Creamer, Elizabeth G.; Ghoston, Michelle R.; Drape, Tiffany; Ruff, Chloe; Mukuni, Joseph

    2012-01-01

    Popular movies were used in a doctoral-level qualitative research methods course as a way to help students learn about how to collect and analyze qualitative observational data in order to develop a grounded theory. The course was designed in such a way that collaboration was central to the generation of knowledge. Using media depictions had the…

  3. Effects of Guided Writing Strategies on Students' Writing Attitudes Based on Media Richness Theory

    Science.gov (United States)

    Lan, Yu-Feng; Hung, Chun-Ling; Hsu, Hung-Ju

    2011-01-01

    The purpose of this paper is to develop different guided writing strategies based on media richness theory and further evaluate the effects of these writing strategies on younger students' writing attitudes in terms of motivation, enjoyment and anxiety. A total of 66 sixth-grade elementary students with an average age of twelve were invited to…

  4. Media Accountability Online in Israel. An application of Bourdieu’s field theory

    Directory of Open Access Journals (Sweden)

    Ronja Kniep

    2015-12-01

    Full Text Available Due to structural changes in journalism, such as deregulation, privatisation and the influence of new technologies, it has become increasingly important to study media accountability (MA. By applying Bourdieu’s theory of social fields, this paper proposes a new approach to do so: MA is defined as a function of both journalistic autonomy and influence in the media field. Here, online communication potentially widens the scope of action for media’s transparency, responsiveness as well as the articulation of media criticism by a variety of actors. In Israel, media criticism is driven by the agent’s struggle for interpretive authority over public discourse in a politically polarized society. Semi-structured interviews with Israeli journalists, media activists and experts suggest that journalistic agents who have yet to earn credibility and reputation exploit online communication to its full potential, while agents in the field of power tend to dismiss online criticism. The influence of the audience’s media criticism is not solely dependent on the technical ability of connecting and hearing the voices of the masses; it has to be in combination with symbolic or political capital. However, the demand for media’s social responsibility is also related to being more careful and less critical, which is very evident in Israel. Thus, it is important to critically reflect on what happens when media accountability practices become more efficient and a stronger sense for “being watched” develops.

  5. Theorizing "Lay Theories of Media": A Case Study of the Dissent! Network at the 2005 Gleneagles G8 Summit

    NARCIS (Netherlands)

    P. McCurdy (Patrick)

    2011-01-01

    textabstractDrawing on "active audience studies" and recent theories of mediation, the concept of "lay theories of media" is proposed as a means to understand how social movement actors think about and interact with news media as part of the "practice" of activism. The argument is made via a case st

  6. Theory of liquids and other disordered media a short introduction

    CERN Document Server

    Schirmacher, Walter

    2015-01-01

    This set of lectures provides an introduction to the structure, thermodynamics and dynamics of liquids, binary solutions and polymers at a level that will enable graduate students and non-specialist researchers to understand more specialized literature and to possibly start their own work in this field. Part I starts with the introduction of distribution functions, which describe the statistical arrangements of atoms or molecules in a simple liquid. The main concepts involve mean field theories like the Perkus-Yevick theory and the random phase approximation, which relate the forces to the distribution functions. In order to provide a concise, self-contained text, an understanding of the general statistical mechanics of an interacting many-body system is assumed. The fact that in a classic liquid the static and dynamic aspects of such a system can be discussed separately forms the basis of the two-fold structure of this approach. In order to allow polymer melts and solutions to be discussed, a short chapter a...

  7. Convective Interaction Media (CIM)--short layer monolithic chromatographic stationary phases.

    Science.gov (United States)

    Podgornik, Ales; Strancar, Ales

    2005-01-01

    Modern downstream processing requires fast and highly effective methods to obtain large quantities of highly pure substances. Commonly applied method for this purpose is chromatography. However, its main drawback is its throughput since purification, especially of large molecules, requires long process time. To overcome this problem several new stationary phases were introduced, among which short layer monoliths show superior properties for many applications. The purpose of this review is to give an overview about short methacrylate monolithic columns commercialised under the trademark Convective Interaction Media (CIM). Their unique properties are described from different perspectives, explaining reasons for their application on various areas. Approaches to prepare large volume methacrylate monolithic column are discussed and optimal solutions are given. Different examples of CIM monolithic column implementation are summarised in the last part of the article to give the reader an idea about their advantages.

  8. Convective mixing in vertically-layered porous media: The linear regime and the onset of convection

    Science.gov (United States)

    Ghorbani, Zohreh; Riaz, Amir; Daniel, Don

    2017-08-01

    We study the effect of permeability heterogeneity on the stability of gravitationally unstable, transient, diffusive boundary layers in porous media. Permeability is taken to vary periodically in the horizontal plane normal to the direction of gravity. In contrast to the situation for vertical permeability variation, the horizontal perturbation structures are multimodal. We therefore use a two-dimensional quasi-steady eigenvalue analysis as well as a complementary initial value problem to investigate the stability behavior in the linear regime, until the onset of convection. We find that thick permeability layers enhance instability compared with thin layers when heterogeneity is increased. On the contrary, for thin layers the instability is weakened progressively with increasing heterogeneity to the extent that the corresponding homogeneous case is more unstable. For high levels of heterogeneity, we find that a small change in the permeability field results in large variations in the onset time of convection, similar to the instability event in the linear regime. However, this trend does not persist unconditionally because of the reorientation of vorticity pairs due to the interaction of evolving perturbation structures with heterogeneity. Consequently, an earlier onset of instability does not necessarily imply an earlier onset of convection. A resonant amplification of instability is observed within the linear regime when the dominant perturbation mode is equal to half the wavenumber of permeability variation. On the other hand, a substantial damping occurs when the perturbation mode is equal to the harmonic and sub-harmonic components of the permeability wavenumber. The phenomenon of such harmonic interactions influences both the onset of instability as well as the onset of convection.

  9. Exact traveltime computation in multi-layered transversely isotropic media with vertical symmetry axis

    Institute of Scientific and Technical Information of China (English)

    TANG Wei; LI Lei

    2008-01-01

    An approach to calculate the accurate ray paths and travelfimes in multi-layered VTI media (transversely isotropic media with a vertical symmetry axis) is proposed. The expressions of phase velocity, group velocity and Snell's law used for computation are all explicit and exact. The calculation of ray paths and traveltimes for a given ele- mentary wave is equivalent to that of a transmission problem which is much easier to be treated with the formulae proposed. In the section of numerical examples, the processes of implementation are described at length using a multi-arrival example and a head-wave example. Lastly, the exact and approximate traveltime curves for the same elementary wave are calculated from the exact formulae and Thomsen's approximations, respectively. The com- parison of the curves reveals the increase of errors arising from the repeated use of approximations and indicates the limited applicable range of approximations. It is emphasized that one should keep in mind the applicable range of an approximation when using it.

  10. Effect of Media Opacity on Retinal Nerve Fiber Layer Thickness Measurements by Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Dae Woong Lee

    2010-01-01

    Full Text Available Purpose: To assess the effect of ocular media opacity on retinal nerve fiber layer (RNFL thickness measurements by optical coherence tomography (OCT. Methods: In this prospective, non-randomized clinical study, ocular examinations and OCT measurements were performed on 77 cataract patients, 80 laser refractive surgery patients and 90 patients whose signal strength on OCT was different on two consecutive measurements. None of the eyes had preexisting retinal or optic nerve pathology, including glaucoma. Cataracts were classified according to the Lens Opacity Classification System III (LOCS III. All eyes were scanned with the Stratus OCT using the Fast RNFL program before and three months after surgery. Internal fixation was used during scanning and all eyes underwent circular scans around the optic disc with a diameter of 3.4 mm. Results: Average RNFL thickness, quadrant thickness and signal strength significantly increased after cataract surgery (P<0.05. Cortical and posterior subcapsular cataracts, but not nuclear cataracts, had a significant influence on RNFL thickness measurements (P<0.05. There was no significant difference between OCT parameters before and after laser refractive surgery. In eyes for which different signal strengths were observed, significantly larger RNFL thickness values were obtained on scans with higher signal strengths. Conclusion: OCT parameters are affected by ocular media opacity because of changes in signal strength; cortical cataracts have the most significant effect followed by posterior subcapsular opacities. Laser refractive procedures do not seem to affect OCT parameters significantly.

  11. Fast electromagnetic modeling in cylindrically layered media excited by eccentred magnetic dipole

    Science.gov (United States)

    Nikitenko, Marina; Itskovich, Gregory B.; Seryakov, Alexander

    2016-06-01

    We developed a fast algorithm to calculate a response of cylindrically layered media excited by the vertical magnetic dipole eccentred with respect to the axis of symmetry. The algorithm calculates response in the range of frequencies typical for induction and dielectric logging. The media conductivity and dielectric constant are described by piecewise-constant functions. The corresponding boundary value problem is solved by method of separation of variables. Fourier transform is applied to Maxwell equations and boundary conditions to express field components through Fourier transforms of vertical components of an electrical and magnetic field. In addition, an expansion of vertical components into an infinite series with respect to angular harmonics is used to reduce the original problem to a series of 1-D problems that only depend on the radial coordinate. The solution to each 1-D radial problem for the angular harmonics is presented as a linear combination of modified Bessel functions. Finally, inverse Fourier transformation is applied to the angular harmonics of vertical components to derive electrical and magnetic field of the original boundary value problem. We provide detailed discussion on the elements that are critical for the numerical implementation of the algorithm: a proper normalization, convergence, and integration. Specifically, we show how to perform integration in the complex plane by avoiding intersection of the integration pass with the cuts located on the Riemann surface. Numerical results show the usefulness of the algorithm for solving inverse problems and for studying the effect of eccentricity in induction and dielectric logging.

  12. Micro-acting Force in Boundary Layer in Low-Permeability Porous Media

    Institute of Scientific and Technical Information of China (English)

    FENG Yu-Liang; ZHANG Yuan; JI Bing-Yu; MU Wen-Zhi

    2011-01-01

    There are lots of reasons to restrict a low-permeability oil layer to enhance the recovery factor.Based on the research results of non-Darcy flow, microflow of water drive and micro-acting force in low permeability porous media are studied by establishing the expression of fluid viscosity factor.Numerical calculation shows that under the condition of L/S interaction, the radial velocity distribution near the solid wall changes obviously, and the curve form changes from convex to concave.The tinier the capillary radius is, the stronger the L/S interaction is.The larger the n value is, more obvionsly the flowing velocity decreases.The results will help people to deal with improving recovery factor of low permeability reservoir, and understanding the fluid flow behavior in blood capillary.%@@ There are lots of reasons to restrict a low-permeability oil layer to enhance the recovery factor.Based on the research results of non-Darcy flow, microfiow of water drive and micro-acting force in low permeability porous media are studied by establishing the expression of fluid viscosity factor.Numerical calculation shows that under the condition of L/S interaction, the radial velocity distribution near the solid wall changes obviously, and the curve form changes from convex to concave.The tinier the capillary radius is, the stronger the L/S interaction is.The larger the n value is, more obviously the flowing velocity decreases.The results will help people to deal with improving recovery factor of low permeability reservoir, and understanding the fluid How behavior in blood capillary.

  13. Theory of current-free double layers in plasmas

    Science.gov (United States)

    Goswami, K. S.; Saharia, K.; Schamel, H.

    2008-06-01

    The existence of current-free double layers in unmagnetized plasma is studied by means of the quasipotential method applied to the Vlasov-Poisson system. Crucial for its existence are trapped particle populations that are characterized by notches (dips) in the velocity distribution functions at resonant velocity becoming flat at large amplitude limit. The potential drop across the double layer, or its amplitude ψ, can be arbitrarily strong covering the whole range 0pressures. It is, hence, the effective electron (ion) temperature increase (decrease) with increasing potential, caused by the trapped particles, which is responsible for the existence of this two-parameter family of solutions.

  14. Steady-state ab initio laser theory for complex gain media

    CERN Document Server

    Cerjan, Alexander; Stone, A Douglas

    2014-01-01

    We derive and test a generalization of Steady-State Ab Initio Laser Theory (SALT) to treat complex gain media. The generalized theory (C-SALT) is able to treat atomic and molecular gain media with diffusion and multiple lasing transitions, and semiconductor gain media in the free carrier approximation including fully the effect of Pauli blocking. The key assumption of the theory is stationarity of the level populations, which leads to coupled self-consistent equations for the populations and the lasing modes that fully include the effects of openness and non-linear spatial hole-burning. These equations can be solved efficiently for the steady-state lasing properties by a similar iteration procedure as in SALT, where a static gain medium with a single transition is assumed. The theory is tested by comparison to much less efficient Finite Difference Time Domain (FDTD) methods and excellent agreement is found. Using C-SALT to analyze the effects of varying gain diffusion constant we demonstrate a cross-over betw...

  15. Steady-state ab initio laser theory for complex gain media.

    Science.gov (United States)

    Cerjan, Alexander; Chong, Y D; Stone, A Douglas

    2015-03-09

    We derive and test a generalization of the steady-state ab initio laser theory (SALT) to treat complex gain media. The generalized theory (C-SALT) is able to treat atomic and molecular gain media with diffusion and multiple lasing transitions, and semiconductor gain media in the free carrier approximation including fully the effect of Pauli blocking. The key assumption of the theory is stationarity of the level populations, which leads to coupled self-consistent equations for the populations and the lasing modes that fully include the effects of openness and non-linear spatial hole-burning. These equations can be solved efficiently for the steady-state lasing properties by a similar iteration procedure as in SALT, where a static gain medium with a single transition is assumed. The theory is tested by comparison to much less efficient finite difference time domain (FDTD) methods and excellent agreement is found. Using C-SALT to analyze the effects of varying gain diffusion constant we demonstrate a cross-over between the regime of strong spatial hole burning with multimode lasing to a regime of negligible spatial hole burning, leading to gain-clamping, and single mode lasing. The effect of spatially inhomogeneous pumping combined with diffusion is also studied and a relevant length scale for spatial inhomogeneity to persist under these conditions is determined. For the semiconductor gain model, we demonstrate the frequency shift due to Pauli blocking as the pumping strength changes.

  16. On the Nature, Theory, and Modeling of Atmospheric Planetary Boundary Layers

    DEFF Research Database (Denmark)

    Baklanov, Alexander A.; Grisogono, Branko; Bornstein, Robert

    2011-01-01

    The gap between our modern understanding of planetary boundary layer physics and its decades-old representations in current operational atmospheric models is widening, which has stimulated this review of the current state of the art and an analysis of the immediate needs in boundary layer theory...

  17. A hierarchy of high-order theories for modes in an elastic layer

    DEFF Research Database (Denmark)

    Sorokin, Sergey V.; Chapman, C. John

    2015-01-01

    A hierarchy of high-order theories for symmetric and skew-symmetric modes in an infinitely long elastic layer of the constant thickness is derived. For each member of the hierarchy, boundary conditions for layers of the finite length are formulated. The forcing problems at several approximation...

  18. Computing the scattering properties of participating media using Lorenz-Mie theory

    DEFF Research Database (Denmark)

    2007-01-01

    This source code implements Lorenz-Mie theory using the formulas presented in the SIGGRAPH 2007 paper: J. R. Frisvad, N. J. Christensen, and H. W. Jensen: "Computing the Scattering Properties of Participating Media Using Lorenz-Mie Theory". Copyright (c) ACM 2007. This is the author's version...... of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in the Proceedings DVD of SIGGRAPH 2007. The ACM copyright covers publication of the code in whole or in part in any and all forms of media. Permission is granted to anyone...... to use this code as software for any purpose, including commercial applications. However, the software is provided 'as-is' without any warranty....

  19. Decoding social media speak: developing a speech act theory research agenda

    OpenAIRE

    Ludwig, S.; de Ruyter, K.

    2016-01-01

    Purpose\\ud – Drawing on the theoretical domain of speech act theory (SAT) and a discussion of its suitability for setting the agenda for social media research, this study aims to explore a range of research directions that are both relevant and conceptually robust, to stimulate the advancement of knowledge and understanding of online verbatim data.\\ud \\ud Design/methodology/approach\\ud – Examining previously published cross-disciplinary research, the study identifies how recent conceptual and...

  20. Incorporating social role theory into topic models for social media content analysis

    OpenAIRE

    Zhao, Wayne Xin; Wang, Jinpeng; He, Yulan; Nie, Jian-Yun; Wen, Ji-Rong; Li, Xiaoming

    2015-01-01

    In this paper, we explore the idea of social role theory (SRT) and propose a novel regularized topic model which incorporates SRT into the generative process of social media content. We assume that a user can play multiple social roles, and each social role serves to fulfil different duties and is associated with a role-driven distribution over latent topics. In particular, we focus on social roles corresponding to the most common social activities on social networks. Our model is instantiate...

  1. Borders amidst power, State and mass media, from a critical theory standpoint

    Directory of Open Access Journals (Sweden)

    Manuel Ortiz Marín

    2006-07-01

    Full Text Available A conception of the power, from the glance of the Critical Theory that it allows to understand the woven complex that links the relations of power to most of the human activities. This paper also approaches to the State as a regulating element of the different forces from institutional character, that they operate in its interior like structures of power and the function as that the massive mass media in the complexity of the modern societies act.

  2. Permeability analysis of fractured vuggy porous media based on homogenization theory

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the characteristics of fractured vuggy porous media,a novel mathematical model was proposed to model fluid flow in such media on fine scale,i.e.,the discrete fracture-vug network model.The new model consists of three systems:porous rock system,fracture system,and vug system.The fractures and vugs are embedded in porous rock,and the isolated vugs could be connected via the discrete fracture network.The flow in porous rock and fractures follows Darcy’s law,and the vugs system is free fluid region.Using a two-scale homogenization limit theory,we obtained a macroscopic Darcy’s law governing the media on coarse scale.The theoretical formula of the equivalent permeability of the fractured vuggy porous media was derived.The model and method of this paper were verified by some numerical examples.At the end the permeability of some fractured vuggy porous media with typical fracture-vug structures was analyzed.

  3. The Indirect Boundary Element Method (IBEM) for Seismic Response of Topographical Irregularities in Layered Media

    Science.gov (United States)

    Contreras Zazueta, M. A.; Perton, M.; Sanchez-Sesma, F. J.; Sánchez-Alvaro, E.

    2013-12-01

    The seismic hazard assessment of extended developments, such as a dam, a bridge or a pipeline, needs the strong ground motion simulation taking into account the effects of surface geology. In many cases the incoming wave field can be obtained from attenuation relations or simulations for layered media using Discrete Wave Number (DWN). Sometimes there is a need to include in simulations the seismic source as well. A number of methods to solve these problems have been developed. Among them the Finite Element and Finite Difference Methods (FEM and FDM) are generally preferred because of the facility of use. Nevertheless, the analysis of realistic dynamic loading induced by earthquakes requires a thinner mesh of the entire domain to consider high frequencies. Consequently this may imply a high computational cost. The Indirect Boundary Element Method (IBEM) can also be employed. Here it is used to study the response of a site to historical seismic activity. This method is particularly suited to model wave propagation through wide areas as it requires only the meshing of boundaries. Moreover, it is well suited to represent finely the diffraction that can occur on a fault. However, the IBEM has been applied mainly to simple geometrical configurations. In this communication significant refinements of the formulation are presented. Using IBEM we can simulate wave propagation in complex geometrical configurations such as a stratified medium crossed by thin faults or having a complex topography. Two main developments are here described; one integrates the DWN method inside the IBEM in order to represent the Green's functions of stratified media with relatively low computational cost but assuming unbounded parallel flat layers, and the other is the extension of IBEM to deal with multi-regions in contact which allows more versatility with a higher computational cost compared to the first one but still minor to an equivalent FEM formulation. The two approaches are fully

  4. Drift of scroll waves in thin layers caused by thickness features: asymptotic theory and numerical simulations.

    Science.gov (United States)

    Biktasheva, I V; Dierckx, H; Biktashev, V N

    2015-02-13

    A scroll wave in a very thin layer of excitable medium is similar to a spiral wave, but its behavior is affected by the layer geometry. We identify the effect of sharp variations of the layer thickness, which is separate from filament tension and curvature-induced drifts described earlier. We outline a two-step asymptotic theory describing this effect, including asymptotics in the layer thickness and calculation of the drift of so-perturbed spiral waves using response functions. As specific examples, we consider drift of scrolls along thickness steps, ridges, ditches, and disk-shaped thickness variations. Asymptotic predictions agree with numerical simulations.

  5. Extended sources radiation and laplace type integral representation: Application to wave propagation above and within layered media

    Science.gov (United States)

    Filippi, P. J. T.

    1983-11-01

    In has been shown that the sound field reflected by the plane boundary of a layered ground can always be described by a specularly reflected wave, and layer potentials. Despite its generality, this representation is not quite suitable for numerical computation. Dealing with a very simple case, Weyl, and later on Ingard and Thomasson, proposed a representation of the solution in which the layer potential terms are replaced by the sum of surface wave and a Laplace type integral. Such an integral is very convenient for numerical purposes. In this paper, it is shown that this kind of representation can be obtained for a very wide class of sound propagation problems above or within layered media: a half-space bounded by a locally reacting surface, a finite layer of porous medium, a porous medium with depth-varying porosity, a thin elastic plate; wave propagation in shallow water with an impedance bottom. Many other applications could be developed.

  6. Fuzzy structure theory modeling of sound-insulation layers in complex vibroacoustic uncertain systems: theory and experimental validation.

    Science.gov (United States)

    Fernandez, Charles; Soize, Christian; Gagliardini, Laurent

    2009-01-01

    The fuzzy structure theory was introduced 20 years ago in order to model the effects of complex subsystems imprecisely known on a master structure. This theory was only aimed at structural dynamics. In this paper, an extension of that theory is proposed in developing an elastoacoustic element useful to model sound-insulation layers for computational vibroacoustics of complex systems. The simplified model constructed enhances computation time and memory allocation because the number of physical and generalized degrees of freedom in the computational vibroacoustic model is not increased. However, these simplifications introduce model uncertainties. In order to take into account these uncertainties, the nonparametric probabilistic approach recently introduced is used. A robust simplified model for sound-insulation layers is then obtained. This model is controlled by a small number of physical and dispersion parameters. First, the extension of the fuzzy structure theory to elastoacoustic element is presented. Second, the computational vibroacoustic model including such an elastoacoustic element to model sound-insulation layer is given. Then, a design methodology to identify the model parameters with experiments is proposed and is experimentally validated. Finally, the theory is applied to an uncertain vibroacoustic system.

  7. Using a Marginal Structural Model to Design a Theory-Based Mass Media Campaign

    Science.gov (United States)

    Taguri, Masataka; Ishikawa, Yoshiki

    2016-01-01

    Background The essential first step in the development of mass media health campaigns is to identify specific beliefs of the target audience. The challenge is to prioritize suitable beliefs derived from behavioral theory. The purpose of this study was to identify suitable beliefs to target in a mass media campaign to change behavior using a new method to estimate the possible effect size of a small set of beliefs. Methods Data were drawn from the 2010 Japanese Young Female Smoker Survey (n = 500), conducted by the Japanese Ministry of Health, Labor and Welfare. Survey measures included intention to quit smoking, psychological beliefs (attitude, norms, and perceived control) based on the theory of planned behavior and socioeconomic status (age, education, household income, and marital status). To identify suitable candidate beliefs for a mass media health campaign, we estimated the possible effect size required to change the intention to quit smoking among the population of young Japanese women using the population attributable fraction from a marginal structural model. Results Thirteen percent of study participants intended to quit smoking. The marginal structural model estimated a population attributable fraction of 47 psychological beliefs (21 attitudes, 6 norms, and 19 perceived controls) after controlling for socioeconomic status. The belief, “I could quit smoking if my husband or significant other recommended it” suggested a promising target for a mass media campaign (population attributable fraction = 0.12, 95% CI = 0.02–0.23). Messages targeting this belief could possibly improve intention rates by up to 12% among this population. The analysis also suggested the potential for regulatory action. Conclusions This study proposed a method by which campaign planners can develop theory-based mass communication strategies to change health behaviors at the population level. This method might contribute to improving the quality of future mass health

  8. Using a Marginal Structural Model to Design a Theory-Based Mass Media Campaign.

    Directory of Open Access Journals (Sweden)

    Hiromu Nishiuchi

    Full Text Available The essential first step in the development of mass media health campaigns is to identify specific beliefs of the target audience. The challenge is to prioritize suitable beliefs derived from behavioral theory. The purpose of this study was to identify suitable beliefs to target in a mass media campaign to change behavior using a new method to estimate the possible effect size of a small set of beliefs.Data were drawn from the 2010 Japanese Young Female Smoker Survey (n = 500, conducted by the Japanese Ministry of Health, Labor and Welfare. Survey measures included intention to quit smoking, psychological beliefs (attitude, norms, and perceived control based on the theory of planned behavior and socioeconomic status (age, education, household income, and marital status. To identify suitable candidate beliefs for a mass media health campaign, we estimated the possible effect size required to change the intention to quit smoking among the population of young Japanese women using the population attributable fraction from a marginal structural model.Thirteen percent of study participants intended to quit smoking. The marginal structural model estimated a population attributable fraction of 47 psychological beliefs (21 attitudes, 6 norms, and 19 perceived controls after controlling for socioeconomic status. The belief, "I could quit smoking if my husband or significant other recommended it" suggested a promising target for a mass media campaign (population attributable fraction = 0.12, 95% CI = 0.02-0.23. Messages targeting this belief could possibly improve intention rates by up to 12% among this population. The analysis also suggested the potential for regulatory action.This study proposed a method by which campaign planners can develop theory-based mass communication strategies to change health behaviors at the population level. This method might contribute to improving the quality of future mass health communication strategies and further

  9. Dynamic characterization of partially saturated engineered porous media and gas diffusion layers using hydraulic admittance

    Science.gov (United States)

    Cheung, Perry; Fairweather, Joseph D.; Schwartz, Daniel T.

    2012-09-01

    Simple laboratory methods for determining liquid water distribution in polymer electrolyte membrane fuel cell gas diffusion layers (GDLs) are needed to engineer better GDL materials. Capillary pressure vs. liquid saturation measurements are attractive, but lack the ability to probe the hydraulic interconnectivity and distribution within the pore structure. Hydraulic admittance measurements of simple capillary bundles have recently been shown to nicely measure characteristics of the free-interfaces and hydraulic path. Here we examine the use of hydraulic admittance with a succession of increasingly complex porous media, starting with a laser-drilled sample with 154 asymmetric pores and progress to the behavior of Toray TGP-H090 carbon papers. The asymmetric laser-drilled sample clearly shows hydraulic admittance measurements are sensitive to sample orientation, especially when examined as a function of saturation state. Finite element modeling of the hydraulic admittance is consistent with experimental measurements. The hydraulic admittance spectra from GDL samples are complex, so we examine trends in the spectra as a function of wet proofing (0% and 40% Teflon loadings) as well as saturation state of the GDL. The presence of clear peaks in the admittance spectra for both GDL samples suggests a few pore types are largely responsible for transporting liquid water.

  10. Residual homogenization for seismic forward and inverse problems in layered media

    Science.gov (United States)

    Capdeville, Yann; Stutzmann, Éléonore; Wang, Nian; Montagner, Jean-Paul

    2013-07-01

    An elastic wavefield propagating in an inhomogeneous elastic medium is only sensitive in an effective way to inhomogeneities much smaller than its minimum wavelength. The corresponding effective medium, or homogenized medium, can be computed thanks to the non-periodic homogenization technique. In the seismic imaging context, limiting ourselves to layered media, we numerically show that a tomographic elastic model which results of the inversion of limited frequency band seismic data is an homogenized model. Moreover, we show that this homogenized model is the same as the model that can be computed with the non-periodic homogenization technique. We first introduce the notion of residual homogenization, which is computing the effective properties of the difference between a reference model and a `real' model. This is necessary because most imaging technique parametrizations use a reference model that often contains small scales, such as elastic discontinuities. We then use a full-waveform inversion method to numerically show that the result of the inversion is indeed the homogenized residual model. The full-waveform inversion method used here has been specifically developed for that purpose. It is based on the iterative Gauss-Newton least-square non-linear optimization technique, using full normal mode coupling to compute the partial Hessian and gradient. The parametrization has been designed according to the residual homogenized parameters allowing to build a real multiscale inversion with progressive frequency band enrichment along the Gauss-Newton iterations.

  11. Electromagnetic Scattering and Inverse Scattering of Layered Media with a Slightly Rough Surface

    Institute of Scientific and Technical Information of China (English)

    LIN Zhi-Wei; XU Xin ZHANG Xiao-Juan; FANG Guang-You

    2011-01-01

    An electromagnetic (EM) scattering model for layered media covered by a 3D infinite rough surface and the corresponding inversion technique are investigated. The work aims at remote sensing the surface roughness and dielectric constant for different depths of bear soil through radar measurement data. The forward problem is carried out by the wave decomposition method. The small perturbation method (SPM) and EM boundary conditions are employed to solve the integral equations introduced by the wave decomposition method. The second-order SPM solution of the scattering field is involved in the computation of the forward problem for the first time. The backscattering coefficients of multiple frequencies, multiple angles and multiple polarizations are employed to create a nonlinear optimization problem. A genetic algorithm is introduced to help the inversion procedure approach to the global minimum of the cost function. Examples are carried out to validate the inversion technique. The inversion results show good agreement with the forward problem with given parameters and pose good tolerance to the input data with the additive white Gaussian noise.

  12. Effects of density distribution of scattering media on radiation transfer. Case of growing frost layer; Fukusha denpa ni ataeru sanransei baitai no mitsudo bunpu no eikyo. Seicho kateini aru shimoso no baai

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, A.; Washio, S. [Okayama University, Okayama (Japan); Haida, T. [NGK Insulators, Ltd., Nagoya (Japan); Matsumoto, E. [Oji Paper Co. Ltd., Tokyo (Japan)

    1999-09-25

    The main interest was taken in the effects of the density distribution on the radiation transfer in the scattering media. The frost layer in the early growth stage under the control of diffusion was chosen as the media. Numerical analysis of the radiation transfer was carried out by using a modified Monte Carlo method on the basis of the geometrical optics. A diffusion limited aggregation theory was introduced to simulate the growth of frost layer with treelike structure. The relation between the density distribution and the transmittance of the simulated model was made clear by the numerical analysis. On the basis of its result, the optical measurements in the visible wavelength region were utilized to evaluate the density distribution in the frost layer, which varied with the cooling condition, from the transmittance values. (author)

  13. Tensor Green's function evaluation in arbitrarily anisotropic, layered media using complex-plane Gauss-Laguerre quadrature.

    Science.gov (United States)

    Sainath, Kamalesh; Teixeira, Fernando L

    2014-05-01

    We discuss the application of complex-plane Gauss-Laguerre quadrature (CGLQ) to efficiently evaluate two-dimensional Fourier integrals arising as the solution to electromagnetic fields radiated by elementary dipole antennas embedded within planar-layered media exhibiting arbitrary material parameters. More specifically, we apply CGLQ to the long-standing problem of rapidly and efficiently evaluating the semi-infinite length "tails" of the Fourier integral path while simultaneously and robustly guaranteeing absolute, exponential convergence of the field solution despite diversity in the doubly anisotropic layer parameters, source type (i.e., electric or equivalent magnetic dipole), source orientation, observed field type (magnetic or electric), (nonzero) frequency, and (nonzero) source-observer separation geometry. The proposed algorithm exhibits robustness despite unique challenges arising for the fast evaluation of such two-dimensional integrals. Herein we develop the mathematical treatment to rigorously evaluate the tail integrals using CGLQ, as well as discuss and address the specific issues posed to the CGLQ method when anisotropic, layered media are present. To empirically demonstrate the CGLQ algorithm's computational efficiency, versatility, and accuracy, we perform a convergence analysis along with two case studies related to modeling of electromagnetic resistivity tools employed in geophysical prospection of layered, anisotropic Earth media and validating the ability of isoimpedance substrates to enhance the radiation performance of planar antennas placed in close proximity to metallic ground planes.

  14. Waves and Structures in Nonlinear Nondispersive Media General Theory and Applications to Nonlinear Acoustics

    CERN Document Server

    Gurbatov, S N; Saichev, A I

    2012-01-01

    "Waves and Structures in Nonlinear Nondispersive Media: General Theory and Applications to Nonlinear Acoustics” is devoted completely to nonlinear structures. The general theory is given here in parallel with mathematical models. Many concrete examples illustrate the general analysis of Part I. Part II is devoted to applications to nonlinear acoustics, including specific nonlinear models and exact solutions, physical mechanisms of nonlinearity, sawtooth-shaped wave propagation, self-action phenomena, nonlinear resonances and engineering application (medicine, nondestructive testing, geophysics, etc.). This book is designed for graduate and postgraduate students studying the theory of nonlinear waves of various physical nature. It may also be useful as a handbook for engineers and researchers who encounter the necessity of taking nonlinear wave effects into account of their work. Dr. Gurbatov S.N. is the head of Department, and Vice Rector for Research of Nizhny Novgorod State University. Dr. Rudenko O.V. is...

  15. Diffusion of a Rouse chain in porous media: A mode-coupling-theory study

    Science.gov (United States)

    Ding, Huai; Jiang, Huijun; Zhao, Nanrong; Hou, Zhonghuai

    2017-01-01

    We use a kinetic mode-coupling theory (MCT) combining with generalized Langevin equation (GLE) to study the diffusion and conformational dynamics of a bead-spring Rouse chain (RC) dissolved in porous media. The media contains fluid particles and immobile matrix ones wherein the latter leads to the lack of translational invariance. The friction kernel ζ (t ) used in the GLE can be obtained directly by adopting a simple density-functional approach in which the density correlators calculated by MCT equations of porous media serve as inputs. Due to cage effects generated by surrounding particles, ζ (t ) shows a very long tail memory in the high volume fraction of fluid and matrix. It is found that the long-time center-of-mass diffusion constant DCM of the RC decreases with the increment of volume fraction, influencing more strongly by the matrix particles than by the fluid ones. The auto-correlation function (ACF) of the end-to-end distance fluctuation can also be calculated theoretically based on GLE. Of particular interest is that the power-law region of ACF has a nearly fixed length in logarithmic scale when it shifts to longer time range, with increasing the volume fraction of media particles. Moreover, the effect of lack of translational invariance has been investigated by comparing the results between fluid-matrix and pure fluid cases under identical total volume fraction.

  16. Automation of Presentation Record Production Based on Rich-Media Technology Using SNT Petri Nets Theory.

    Science.gov (United States)

    Martiník, Ivo

    2015-01-01

    Rich-media describes a broad range of digital interactive media that is increasingly used in the Internet and also in the support of education. Last year, a special pilot audiovisual lecture room was built as a part of the MERLINGO (MEdia-rich Repository of LearnING Objects) project solution. It contains all the elements of the modern lecture room determined for the implementation of presentation recordings based on the rich-media technologies and their publication online or on-demand featuring the access of all its elements in the automated mode including automatic editing. Property-preserving Petri net process algebras (PPPA) were designed for the specification and verification of the Petri net processes. PPPA does not need to verify the composition of the Petri net processes because all their algebraic operators preserve the specified set of the properties. These original PPPA are significantly generalized for the newly introduced class of the SNT Petri process and agent nets in this paper. The PLACE-SUBST and ASYNC-PROC algebraic operators are defined for this class of Petri nets and their chosen properties are proved. The SNT Petri process and agent nets theory were significantly applied at the design, verification, and implementation of the programming system ensuring the pilot audiovisual lecture room functionality.

  17. Automation of Presentation Record Production Based on Rich-Media Technology Using SNT Petri Nets Theory

    Directory of Open Access Journals (Sweden)

    Ivo Martiník

    2015-01-01

    Full Text Available Rich-media describes a broad range of digital interactive media that is increasingly used in the Internet and also in the support of education. Last year, a special pilot audiovisual lecture room was built as a part of the MERLINGO (MEdia-rich Repository of LearnING Objects project solution. It contains all the elements of the modern lecture room determined for the implementation of presentation recordings based on the rich-media technologies and their publication online or on-demand featuring the access of all its elements in the automated mode including automatic editing. Property-preserving Petri net process algebras (PPPA were designed for the specification and verification of the Petri net processes. PPPA does not need to verify the composition of the Petri net processes because all their algebraic operators preserve the specified set of the properties. These original PPPA are significantly generalized for the newly introduced class of the SNT Petri process and agent nets in this paper. The PLACE-SUBST and ASYNC-PROC algebraic operators are defined for this class of Petri nets and their chosen properties are proved. The SNT Petri process and agent nets theory were significantly applied at the design, verification, and implementation of the programming system ensuring the pilot audiovisual lecture room functionality.

  18. Automation of Presentation Record Production Based on Rich-Media Technology Using SNT Petri Nets Theory

    Science.gov (United States)

    Martiník, Ivo

    2015-01-01

    Rich-media describes a broad range of digital interactive media that is increasingly used in the Internet and also in the support of education. Last year, a special pilot audiovisual lecture room was built as a part of the MERLINGO (MEdia-rich Repository of LearnING Objects) project solution. It contains all the elements of the modern lecture room determined for the implementation of presentation recordings based on the rich-media technologies and their publication online or on-demand featuring the access of all its elements in the automated mode including automatic editing. Property-preserving Petri net process algebras (PPPA) were designed for the specification and verification of the Petri net processes. PPPA does not need to verify the composition of the Petri net processes because all their algebraic operators preserve the specified set of the properties. These original PPPA are significantly generalized for the newly introduced class of the SNT Petri process and agent nets in this paper. The PLACE-SUBST and ASYNC-PROC algebraic operators are defined for this class of Petri nets and their chosen properties are proved. The SNT Petri process and agent nets theory were significantly applied at the design, verification, and implementation of the programming system ensuring the pilot audiovisual lecture room functionality. PMID:26258164

  19. Monte Carlo simulation and self-consistent integral equation theory for polymers in quenched random media.

    Science.gov (United States)

    Sung, Bong June; Yethiraj, Arun

    2005-08-15

    The conformational properties and static structure of freely jointed hard-sphere chains in matrices composed of stationary hard spheres are studied using Monte Carlo simulations and integral equation theory. The simulations show that the chain size is a nonmonotonic function of the matrix density when the matrix spheres are the same size as the monomers. When the matrix spheres are of the order of the chain size the chain size decreases monotonically with increasing matrix volume fraction. The simulations are used to test the replica-symmetric polymer reference interaction site model (RSP) integral equation theory. When the simulation results for the intramolecular correlation functions are input into the theory, the agreement between theoretical predictions and simulation results for the pair-correlation functions is quantitative only at the highest fluid volume fractions and for small matrix sphere sizes. The RSP theory is also implemented in a self-consistent fashion, i.e., the intramolecular and intermolecular correlation functions are calculated self-consistently by combining a field theory with the integral equations. The theory captures qualitative trends observed in the simulations, such as the nonmonotonic dependence of the chain size on media fraction.

  20. Roles, trust, and reputation in social media knowledge markets theory and methods

    CERN Document Server

    Matei, Sorin

    2015-01-01

    This title discusses the emerging trends in defining, measuring, and operationalizing reputation as a new and essential component of the knowledge that is generated and consumed online. The book also proposes a future research agenda related to these issues—with the ultimate goal of shaping the next generation of theoretical and analytic strategies needed for understanding how knowledge markets are influenced by social interactions and reputations built around functional roles. Roles, Trust, and Reputation in Social Media Knowledge Markets exposes issues that have not been satisfactorily dealt with in the current literature. In a broader sense, the volume aims to change the way in which knowledge generation in social media spaces is understood and utilized. The tools, theories, and methodologies proposed here offer concrete avenues for developing the next generation of research strategies and applications that will help: tomorrow’s information consumers make smarter choices, developers to create new tools...

  1. Symmetry relations in the generalized Lorenz-Mie theory for lossless negative refractive index media

    Science.gov (United States)

    André Ambrosio, Leonardo

    2016-09-01

    In this paper we present a theoretical analysis of the generalized Lorenz-Mie theory for negative refractive index (NRI) media and spherical scatterers, extending the well-known concepts and definitions found in the literature involving dielectric or positive refractive index (PRI) particles. The consequences of a negative phase velocity and an anti-parallelism of the wave vector with respect to the Poynting vector are investigated and interpreted in this framework and, together with the symmetries found for the beam-shape coefficients when compared to the conventional PRI case, it is shown that the description of plane waves, Gaussian beams and, more generally, on-axis azimuthally symmetric waves along a NRI medium, their fields and all physical properties can be conveniently correlated with that of dielectric media once the electromagnetic response functions are replaced by their corresponding dielectric counterparts.

  2. XTEM and AES study of the microstructure for high density Co-Cr-Nb-Pt double layered perpendicular magnetic recording media

    Energy Technology Data Exchange (ETDEWEB)

    Safran, G. E-mail: safran@ait.pref.akita.jp; Ariake, Jun; Honda, Naoki; Ouchi, Kazuhiro; Czigany, Zsolt; Barna, P.B.; Menyhard, M.; Radnoczi, G

    2001-10-01

    A Ti intermediate layer between permalloy and Co-Cr-Nb-Pt storage layer improved the magnetic properties of double layered media. Cr segregation, Ni and Co enrichment was found within the Ti layer by AES. XTEM study revealed reduced crystallite size of Co-Cr-Nb-Pt due to nucleation in an amorphous phase formed as a result of a chemical interaction at the interface of the Ti and permalloy layers.

  3. A hierarchy of high-order theories for modes in an elastic layer

    DEFF Research Database (Denmark)

    Sorokin, Sergey V.; Chapman, C. John

    2015-01-01

    A hierarchy of high-order theories for symmetric and skew-symmetric modes in an infinitely long elastic layer of the constant thickness is derived. For each member of the hierarchy, boundary conditions for layers of the finite length are formulated. The forcing problems at several approximation l...... levels are solved with use of the bi-orthogonality conditions. Accuracy of these approximations is assessed by comparison of results with the exact solution of the Rayleigh-Lamb problem...

  4. Radiative transfer theory for active remote sensing of a layer of small ellipsoidal scatterers. [of vegetation

    Science.gov (United States)

    Tsang, L.; Kubacsi, M. C.; Kong, J. A.

    1981-01-01

    The radiative transfer theory is applied within the Rayleigh approximation to calculate the backscattering cross section of a layer of randomly positioned and oriented small ellipsoids. The orientation of the ellipsoids is characterized by a probability density function of the Eulerian angles of rotation. The radiative transfer equations are solved by an iterative approach to first order in albedo. In the half space limit the results are identical to those obtained via the approach of Foldy's and distorted Born approximation. Numerical results of the theory are illustrated using parameters encountered in active remote sensing of vegetation layers. A distinctive characteristic is the strong depolarization shown by vertically aligned leaves.

  5. Optimal damping ratios of multi-axial perfectly matched layers for elastic-wave modeling in general anisotropic media

    CERN Document Server

    Gao, Kai

    2016-01-01

    The conventional Perfectly Matched Layer (PML) is unstable for certain kinds of anisotropic media. This instability is intrinsic and independent of PML formulation or implementation. The Multi-axial PML (MPML) removes such instability using a nonzero damping coefficient in the direction parallel with the interface between a PML and the investigated domain. The damping ratio of MPML is the ratio between the damping coefficients along the directions parallel with and perpendicular to the interface between a PML and the investigated domain. No quantitative approach is available for obtaining these damping ratios for general anisotropic media. We develop a quantitative approach to determining optimal damping ratios to not only stabilize PMLs, but also minimize the artificial reflections from MPMLs. Numerical tests based on finite-difference method show that our new method can effectively provide a set of optimal MPML damping ratios for elastic-wave propagation in 2D and 3D general anisotropic media.

  6. Application of percolation theory to microtomography of structured media: percolation threshold, critical exponents, and upscaling.

    Science.gov (United States)

    Liu, Jie; Regenauer-Lieb, Klaus

    2011-01-01

    Percolation theory provides a tool for linking microstructure and macroscopic material properties. In this paper, percolation theory is applied to the analysis of microtomographic images for the purpose of deriving scaling laws for upscaling of properties. We have tested the acquisition of quantities such as percolation threshold, crossover length, fractal dimension, and critical exponent of correlation length from microtomography. By inflating or deflating the target phase and percolation analysis, we can get a critical model and an estimation of the percolation threshold. The crossover length is determined from the critical model by numerical simulation. The fractal dimension can be obtained either from the critical model or from the relative size distribution of clusters. Local probabilities of percolation are used to extract the critical exponent of the correlation length. For near-isotropic samples such as sandstone and bread, the approach works very well. For strongly anisotropic samples, such as highly deformed rock (mylonite) and a tree branch, the percolation threshold and fractal dimension can be assessed with accuracy. However, the uncertainty of the correlation length makes it difficult to accurately extract its critical exponents. Therefore, this aspect of percolation theory cannot be reliably used for upscaling properties of strongly anisotropic media. Other methods of upscaling have to be used for such media.

  7. A Source-Model Technique for analysis of wave guiding along chains of metallic nanowires in layered media.

    Science.gov (United States)

    Szafranek, Dana; Leviatan, Yehuda

    2011-12-05

    A method for determining the modes that can be guided along infinite chains of metallic nanowires when they are embedded, as in most realistic set-ups, in layered media is presented. The method is based on a rigorous full-wave frequency-domain Source-Model Technique (SMT). The method allows efficient determination of the complex propagation constants and the surface-plasmon type modal fields. Sample results are presented for silver nanowires with circular and triangle-like cross-sections lying in an air-Si-glass layered structure.

  8. On the inverse seismic problem for horizontally layered media: Subsidiary study

    Science.gov (United States)

    Cuer, Michel; Petit, Jean Louis

    The starting point of this work is the inversion of vertical seismic profiling (VSP) data. The usual processing of VSP data by inverse techniques is restricted to 1D propagation model. In this case, the parameters to identify are the acoustic impedance as function of travel time and the seismic source so that we have as unknowns two functions of one variable and as data a function of two variables, the time and the depth positions of geophones. The problem is thus largely overdetermined and an elementary mathematical analysis can be made. The source is modelled as a boundary condition at the top of the geophones zone. So this boundary condition replaces the true source function and the medium parameters above the geophones zone. The question asked by V. Richard from IFP was the "management" of this unknown source when 3D propagation effects are taken into account in horizontally layered medium where the propagation equations are parametrized by the k parameter of the Hankel transform. Now we think that the answer is that it is impossible to work round the fact that there are at least two unknown functions, the source and the medium parameters above the geophones zone. During this study, we have searched for some non local boundary conditions and this was the opportunity to obtain some results on exact transparent conditions for 3D propagation in 1D media (preliminary communication was made by Petit and Cuer (1994)) and on the discretization of such conditions in the acoustic case (preliminary communication was made by Cuer and Petit (1995)). This is the mathematical substance of this work in which the Poisson summation formula is used to prove the stability of a discrete non local boundary condition.

  9. Design & Choice of Media by Applying the Theory of Transactional Distance

    Institute of Scientific and Technical Information of China (English)

    Paul Kawachi

    2004-01-01

    This Paper presents a series of empirical studies involving approx.850 students to show how flexibility in course design should be informed by the student's culture and native language (L1), gender, and age, and explains how to decide on the most appropriate learning technology in course design by applying the Theory of Transactional Distance. Curves are presented to show how academic English reading rates online and offline are affected by the L1, gender, and age (over a wide age range 18 81 years old). To prevent inequitable culturally distinct overload, course design should be modified using hypertext. Choice of media--in particular synchronous versus asynchronous media--is decided according to the Theory of Transactional Distance. This theory is here extended from tutor to one student to multiple students in a group, and the masculinity can be modified. Briefly, at initial maximal distance (D-S-) early on, the community is fostered with synchronous media for cooperative group learning, followed by (D-S+) collaborative learning using one of two frameworks presented to ensure constructivism in asynchronous mode, then (D-S+) collaborative for Guided Didactic Conversation in asynchronous mode, and finally (D+ S-) cooperatively in synchronous mode for reflective sharing of course learning experiences. At each transactional distance, or in each mode, hypertext is purposively designed to complement the cooperative or collaborative style to provide self access support (additional analysis and reasoning to cooperative, and examples to collaborative) to provide equitable content and quality of learning across wide cultural and L1 ranges, to remove gender bias, and to accommodate variations due to student age. Thus, to promote student autonomy and lifelong learning.

  10. Feminist Theory and the Media Representation of a Woman-of-Color Superintendent: Is the World Ready for Cyborgs?

    Science.gov (United States)

    Nozaki, Yoshiko

    2000-01-01

    Discusses recent feminist theory, in particular feminist theory related to "cyborg" identity and examines some media representations of a woman-of-color superintendent. Suggests that the cyborg image offers alternative ways to consider the issue of diversity and educational leadership, including the superintendency. (Author/SLD)

  11. Optimization of flow modeling in fractured media with discrete fracture network via percolation theory

    Science.gov (United States)

    Donado-Garzon, L. D.; Pardo, Y.

    2013-12-01

    Fractured media are very heterogeneous systems where occur complex physical and chemical processes to model. One of the possible approaches to conceptualize this type of massifs is the Discrete Fracture Network (DFN). Donado et al., modeled flow and transport in a granitic batholith based on this approach and found good fitting with hydraulic and tracer tests, but the computational cost was excessive due to a gigantic amount of elements to model. We present in this work a methodology based on percolation theory for reducing the number of elements and in consequence, to reduce the bandwidth of the conductance matrix and the execution time of each network. DFN poses as an excellent representation of all the set of fractures of the media, but not all the fractures of the media are part of the conductive network. Percolation theory is used to identify which nodes or fractures are not conductive, based on the occupation probability or percolation threshold. In a fractured system, connectivity determines the flow pattern in the fractured rock mass. This volume of fluid is driven through connection paths formed by the fractures, when the permeability of the rock is negligible compared to the fractures. In a population of distributed fractures, each of this that has no intersection with any connected fracture do not contribute to generate a flow field. This algorithm also permits us to erase these elements however they are water conducting and hence, refine even more the backbone of the network. We used 100 different generations of DFN that were optimized in this study using percolation theory. In each of the networks calibrate hydrodynamic parameters as hydraulic conductivity and specific storage coefficient, for each of the five families of fractures, yielding a total of 10 parameters to estimate, at each generation. Since the effects of the distribution of fault orientation changes the value of the percolation threshold, but not the universal laws of classical

  12. Numerical model of a non-steady atmospheric planetary boundary layer, based on similarity theory

    DEFF Research Database (Denmark)

    Zilitinkevich, S.S.; Fedorovich, E.E.; Shabalova, M.V.

    1992-01-01

    A numerical model of a non-stationary atmospheric planetary boundary layer (PBL) over a horizontally homogeneous flat surface is derived on the basis of similarity theory. The two most typical turbulence regimes are reproduced: one corresponding to a convectively growing PBL and another correspon...

  13. Organizational and media stress among professional football players: testing an achievement goal theory model.

    Science.gov (United States)

    Kristiansen, E; Halvari, H; Roberts, G C

    2012-08-01

    The purpose of this study was to investigate media and coach-athlete stress experienced by professional football players and their relationship to motivational variables by testing an achievement goal theory (AGT) stress model. In order to do so, we developed scales specifically designed to assess media and coach-athlete stress. Eighty-two elite football players (M(age) =25.17 years, SD=5.19) completed a series of questionnaires. Correlations and bootstrapping were used as primary statistical analyses, supplemented by LISREL, to test the hypotheses. Results revealed that a mastery climate was directly and negatively associated with coach-athlete stress, while a performance climate was directly and positively associated with coach-athlete stress. In addition, an indirect positive path between the performance climate and media stress was revealed through ego orientation. These findings support some of the key postulates of AGT; a mastery climate reduces the perception of stress among athletes, and the converse is true for a performance climate. Coaches of elite footballers are advised to try to reduce the emphasis on performance criteria because of its stress-reducing effects.

  14. Stability of boundary layers with porous suction strips: Experiment and theory

    Science.gov (United States)

    Reynolds, G. A.; Saric, W. S.; Reed, H. L.; Nayfeh, A. H.

    1982-01-01

    Low turbulence tunnel experiments on the stability and transition of 2 D boundary layers on flat plates with and without suction are described. A number of general suction cases are discussed. Test results showed that the maximum stabilization occurred when the suction was moved toward the Branch I neutral point. An analytical study of the stability of two dimensional, incompressible boundary layer flows over plates with suction through porous strips was performed. The mean flow was calculated using linearized triple deck, closed form solutions. The stability results of the triple deck theory are shown to be in good agreement with those of the interacting boundary layers. An analytical optimization scheme for the suction configuration was developd. Numerical calculations were performed corresponding to the experimental configurations. In each case, the theory correctly predicts the experimental results.

  15. Source Similarity and Social Media Health Messages: Extending Construal Level Theory to Message Sources.

    Science.gov (United States)

    Young, Rachel

    2015-09-01

    Social media users post messages about health goals and behaviors to online social networks. Compared with more traditional sources of health communication such as physicians or health journalists, peer sources are likely to be perceived as more socially close or similar, which influences how messages are processed. This experimental study uses construal level theory of psychological distance to predict how mediated health messages from peers influence health-related cognition and behavioral intention. Participants were exposed to source cues that identified peer sources as being either highly attitudinally and demographically similar to or different from participants. As predicted by construal level theory, participants who perceived sources of social media health messages as highly similar listed a greater proportion of beliefs about the feasibility of health behaviors and a greater proportion of negative beliefs, while participants who perceived sources as more dissimilar listed a greater proportion of positive beliefs about the health behaviors. Results of the study could be useful in determining how health messages from peers could encourage individuals to set realistic health goals.

  16. A critical evaluation of the Miller and Miller similar media theory for application to natural soils

    Science.gov (United States)

    Sadeghi, Morteza; Ghahraman, Bijan; Warrick, Arthur W.; Tuller, Markus; Jones, Scott B.

    2016-05-01

    The Miller-Miller similar media theory is widely applied to characterize the spatial variability of soil hydraulic properties. For a group of soils, a distinct scaling factor is commonly assigned to each individual soil to coalesce the soil water characteristic and hydraulic conductivity functions to single curves. It is generally assumed that the Miller-Miller theory is valid as long as soils are "similar" either with regard to their microscopic pore space geometry or the closely related macroscopic soil hydraulic functions. In this paper, it is illustrated that similarity is not the sole required condition for validity of the Miller-Miller theory. In addition, the interrelation between the soil water characteristic and the hydraulic conductivity functions considered for scaling need to be comparable. The interrelation is dependent not only on the pore space geometry, but also on solid-liquid interactions. Hence similar interrelation cannot be concluded from similarity of microscopic pore space geometry. A dimensionless parameter termed the "joint scaling factor" was defined and applied to evaluate the soundness of the interrelation condition for 26 soils from the UNSODA database that were grouped into six classes of similar soils. Obtained results clearly reveal the crucial importance of the interrelation condition for the Miller-Miller scaling theory, which has been hidden behind the "similarity" requirement, and contradict the general belief that Miller-Miller scaling is valid as long as soils are "similar."

  17. Scaled Particle Theory for Multicomponent Hard Sphere Fluids Confined in Random Porous Media.

    Science.gov (United States)

    Chen, W; Zhao, S L; Holovko, M; Chen, X S; Dong, W

    2016-06-23

    The formulation of scaled particle theory (SPT) is presented for a quite general model of fluids confined in a random porous media, i.e., a multicomponent hard sphere (HS) fluid in a multicomponent hard sphere or a multicomponent overlapping hard sphere (OHS) matrix. The analytical expressions for pressure, Helmholtz free energy, and chemical potential are derived. The thermodynamic consistency of the proposed theory is established. Moreover, we show that there is an isomorphism between the SPT for a multicomponent system and that for a one-component system. Results from grand canonical ensemble Monte Carlo simulations are also presented for a binary HS mixture in a one-component HS or a one-component OHS matrix. The accuracy of various variants derived from the basic SPT formulation is appraised against the simulation results. Scaled particle theory, initially formulated for a bulk HS fluid, has not only provided an analytical tool for calculating thermodynamic properties of HS fluid but also helped to gain very useful insight for elaborating other theoretical approaches such as the fundamental measure theory (FMT). We expect that the general SPT for multicomponent systems developed in this work can contribute to the study of confined fluids in a similar way.

  18. Displacements and stresses in composite multi-layered media due to varying temperature and concentrated load

    Institute of Scientific and Technical Information of China (English)

    M. K. Ghosh; M. Kanoria

    2007-01-01

    This paper deals with the determination of the thermo-elastic displacements and stresses in a multi-layered body set up in different layers of different thickness having different elastic properties due to the application of heat and a concentrated load in the uppermost surface of the medium. Each layer is assumed to be made of homogeneous and isotropic elastic material. The relevant displacement components for each layer are taken to be axisymmetric about a line, which is perpendicular to the plane surfaces of all layers. The stress function for each layer, therefore, satisfies a single equation in absence of any body forces. The equation is then solved by integral transform technique. Analytical expressions for thermo-elastic displacements and stresses in the underlying mass and the corresponding numerical codes are constructed for any number of layers. However, the numerical comparison is made for three and four layers.

  19. Intercultural Peers’ effect on Social Identity of Social Media Users:A Critical Study of Consumer Socialization Theory

    OpenAIRE

    Khajeheian, Datis

    2016-01-01

    This research investigates the effect of social media peers on the social identity of consumers. The critical perspective of this research is based on the consumer socialization theory research framework. This framework consists of three levels - the global, national and local peers - and their impact on two constructs, namely the global and local social identity. Adopting the ethnographic approach and a complementary phase of interviews, this study explores the influence of social media peer...

  20. Robust automatic segmentation of corneal layer boundaries in SDOCT images using graph theory and dynamic programming.

    Science.gov (United States)

    Larocca, Francesco; Chiu, Stephanie J; McNabb, Ryan P; Kuo, Anthony N; Izatt, Joseph A; Farsiu, Sina

    2011-06-01

    Segmentation of anatomical structures in corneal images is crucial for the diagnosis and study of anterior segment diseases. However, manual segmentation is a time-consuming and subjective process. This paper presents an automatic approach for segmenting corneal layer boundaries in Spectral Domain Optical Coherence Tomography images using graph theory and dynamic programming. Our approach is robust to the low-SNR and different artifact types that can appear in clinical corneal images. We show that our method segments three corneal layer boundaries in normal adult eyes more accurately compared to an expert grader than a second grader-even in the presence of significant imaging outliers.

  1. Removal of Mn{sup 2+} from water by 'aged' biofilter media: The role of catalytic oxides layers

    Energy Technology Data Exchange (ETDEWEB)

    Sahabi, D.M.; Takeda, M.; Suzuki, I.; Koizurni, J. [Yokohama National University, Kanagawa (Japan). Dept. of Chemical & Energy Engineering

    2009-02-15

    The present work was aimed at evaluating the surface coatings characteristics and autocatalytic manganese oxidation potentials of two groups of 'aged' biofilter media. This refers to the anthracite filter media of a biological water treatment plant on which metal oxides and a biofilm have deposited on the surface of the filter media over long time of filtration. Duplicate samples of anthracite filter media were collected from each of the six filter wells in the plant and classified into two groups, based on their duration of operation, as 3-years filter media and 15-years filter media. Batch experiments showed that the 15-years filter media exhibited very high manganese sorption capacity and were less dependent on the microbial activity than the 3-years filter media. Results of the surface coatings analyses indicated that the biofilter materials is predominantly composed of variable layers of manganese and iron oxides, with microbial biomass contributing only about 3.5 and 1.4% of the dry weight of the surface coatings on the 3- and 15-years filter media respectively. Investigations onto the Mn{sup 2+} sorption by the lyophilized biofilter media showed that, the sorption kinetics on the catalytic oxides layers followed the pseudo-second-order kinetics model, thus suggesting chemisorption as the dominant mechanism of Mn{sup 2+} removal. This implied that manganese removal by these biofilters is mainly by adsorption of Mn{sup 2+} onto the iron and manganese (catalytic) oxides layers and autocatalytic oxidation. The present study has clearly linked MN{sub 2}+ oxidation to the catalytic oxides layers on the aged biofilter media.

  2. Point-to-point connectivity prediction in porous media using percolation theory

    Science.gov (United States)

    Tavagh-Mohammadi, Behnam; Masihi, Mohsen; Ganjeh-Ghazvini, Mostafa

    2016-10-01

    The connectivity between two points in porous media is important for evaluating hydrocarbon recovery in underground reservoirs or toxic migration in waste disposal. For example, the connectivity between a producer and an injector in a hydrocarbon reservoir impact the fluid dispersion throughout the system. The conventional approach, flow simulation, is computationally very expensive and time consuming. Alternative method employs percolation theory. Classical percolation approach investigates the connectivity between two lines (representing the wells) in 2D cross sectional models whereas we look for the connectivity between two points (representing the wells) in 2D aerial models. In this study, site percolation is used to determine the fraction of permeable regions connected between two cells at various occupancy probabilities and system sizes. The master curves of mean connectivity and its uncertainty are then generated by finite size scaling. The results help to predict well-to-well connectivity without need to any further simulation.

  3. Transport processes in macroscopically disordered media from mean field theory to percolation

    CERN Document Server

    Snarskii, Andrei A; Sevryukov, Vladimir A; Morozovskiy, Alexander; Malinsky, Joseph

    2016-01-01

    This book reflects on recent advances in the understanding of percolation systems to present a wide range of transport phenomena in inhomogeneous disordered systems. Further developments in the theory of macroscopically inhomogeneous media are also addressed. These developments include galvano-electric, thermoelectric, elastic properties, 1/f noise and higher current momenta, Anderson localization, and harmonic generation in composites in the vicinity of the percolation threshold. The book describes how one can find effective characteristics, such as conductivity, dielectric permittivity, magnetic permeability, with knowledge of the distribution of different components constituting an inhomogeneous medium. Considered are a wide range of recent studies dedicated to the elucidation of physical properties of macroscopically disordered systems. Aimed at researchers and advanced students, it contains a straightforward set of useful tools which will allow the reader to derive the basic physical properties of compli...

  4. Higher order perturbation theory applied to radiative transfer in non-plane-parallel media

    CERN Document Server

    Box, M A; Davis, A B

    2003-01-01

    Radiative transfer in non-plane-parallel media is a very challenging problem, which is currently the subject of concerted efforts to develop computational techniques which may be used to tackle different tasks. In this paper we develop the full formalism for another technique, based on radiative perturbation theory. With this approach, one starts with a plane-parallel 'base model', for which many solution techniques exist, and treat the horizontal variability as a perturbation. We show that under the most logical assumption as to the base model, the first-order perturbation term is zero for domain-average radiation quantities, so that it is necessary to go to higher order terms. This requires the computation of the Green's function. While this task is by no means simple, once the various pieces have been assembled they may be re-used for any number of perturbations--that is, any horizontal variations.

  5. Conservation Laws for Coupled Hydro-mechanical Processes in Unsaturated Porous Media: Theory and Implementation

    Energy Technology Data Exchange (ETDEWEB)

    Borja, R I; White, J A

    2010-02-19

    We develop conservation laws for coupled hydro-mechanical processes in unsaturated porous media using three-phase continuum mixture theory. From the first law of thermodynamics, we identify energy-conjugate variables for constitutive modeling at macroscopic scale. Energy conjugate expressions identified relate a certain measure of effective stress to the deformation of the solid matrix, the degree of saturation to the matrix suction, the pressure in each constituent phase to the corresponding intrinsic volume change of this phase, and the seepage forces to the corresponding pressure gradients. We then develop strong and weak forms of boundary-value problems relevant for 3D finite element modeling of coupled hydro-mechanical processes in unsaturated porous media. The paper highlights a 3D numerical example illustrating the advances in the solution of large-scale coupled finite element systems, as well as the challenges in developing more predictive tools satisfying the basic conservation laws and the observed constitutive responses for unsaturated porous materials.

  6. Application of renormalization group theory to the large-eddy simulation of transitional boundary layers

    Science.gov (United States)

    Piomelli, Ugo; Zang, Thomas A.; Speziale, Charles G.; Lund, Thomas S.

    1990-01-01

    An eddy viscosity model based on the renormalization group theory of Yakhot and Orszag (1986) is applied to the large-eddy simulation of transition in a flat-plate boundary layer. The simulation predicts with satisfactory accuracy the mean velocity and Reynolds stress profiles, as well as the development of the important scales of motion. The evolution of the structures characteristic of the nonlinear stages of transition is also predicted reasonably well.

  7. Turbulent mixing and layer formation in double-diffusive convection: 3D numerical simulations and theory

    CERN Document Server

    Rosenblum, Erica; Traxler, Adrienne; Stellmach, Stephan

    2010-01-01

    Double-diffusive convection, often referred to as semi-convection in astrophysics, occurs in thermally and compositionally stratified systems which are stable according to the Ledoux-criterion but unstable according to the Schwarzchild criterion. This process has been given relatively little attention so far, and its properties remain poorly constrained. In this paper, we present and analyze a set of three-dimensional simulations of this phenomenon in a Cartesian domain under the Boussinesq approximation. We find that in some cases the double-diffusive convection saturates into a state of homogeneous turbulence, but with turbulent fluxes several orders of magnitude smaller than those expected from direct overturning convection. In other cases the system rapidly and spontaneously develops closely-packed thermo-compositional layers, which later successively merge until a single layer is left. We compare the output of our simulations with an existing theory of layer formation in the oceanographic context, and fi...

  8. A stable high-order perturbation of surfaces method for numerical simulation of diffraction problems in triply layered media

    Science.gov (United States)

    Hong, Youngjoon; Nicholls, David P.

    2017-02-01

    The accurate numerical simulation of linear waves interacting with periodic layered media is a crucial capability in engineering applications. In this contribution we study the stable and high-order accurate numerical simulation of the interaction of linear, time-harmonic waves with a periodic, triply layered medium with irregular interfaces. In contrast with volumetric approaches, High-Order Perturbation of Surfaces (HOPS) algorithms are inexpensive interfacial methods which rapidly and recursively estimate scattering returns by perturbation of the interface shape. In comparison with Boundary Integral/Element Methods, the stable HOPS algorithm we describe here does not require specialized quadrature rules, periodization strategies, or the solution of dense non-symmetric positive definite linear systems. In addition, the algorithm is provably stable as opposed to other classical HOPS approaches. With numerical experiments we show the remarkable efficiency, fidelity, and accuracy one can achieve with an implementation of this algorithm.

  9. Tensor Greens' Function Evaluation in Arbitrarily Anisotropic, Layered Media using Complex-Plane Gauss-Laguerre Quadrature

    CERN Document Server

    Sainath, Kamalesh

    2014-01-01

    We discuss the application of Complex-Plane Gauss-Laguerre Quadrature (CGLQ) to efficiently evaluate two-dimensional Fourier integrals arising as the solution to electromagnetic fields radiated by elementary dipole antennas embedded within planar-layered media with arbitrary material parameters. More specifically, we apply CGLQ to the long-standing problem of rapidly and efficiently evaluating the semi-infinite length "tails" of the Fourier integral path while simultaneously and robustly guaranteeing absolute, exponential convergence of the field solution despite diversity in the doubly anisotropic layer parameters, source type (i.e., electric or equivalent magnetic dipole), source orientation, observed field type (magnetic or electric), (non-zero) frequency, and (non-zero) source-observer separation geometry. The proposed algorithm exhibits robustness despite unique challenges arising for the fast evaluation of such two-dimensional integrals. Herein, we (1) develop the mathematical treatment to rigorously ev...

  10. Pedagogical Media Competencies of Preservice Teachers in Germany and the United States: A Comparative Analysis of Theory and Practice

    Science.gov (United States)

    Tiede, Jennifer; Grafe, Silke; Hobbs, Renee

    2015-01-01

    Teachers need knowledge and skills to make effective use of the growing variety of media and technology texts and tools available for use in elementary and secondary education. For this reason, pedagogical media competencies are highly relevant for teachers' professional development. The theory of media pedagogical competencies is first defined…

  11. Layered Double Hydroxides as Effective Adsorbents for U(VI and Toxic Heavy Metals Removal from Aqueous Media

    Directory of Open Access Journals (Sweden)

    G. N. Pshinko

    2013-01-01

    Full Text Available Capacities of different synthesized Zn,Al-hydrotalcite-like adsorbents, including the initial carbonate [Zn4Al2(OH12]·CO3·8H2O and its forms intercalated with chelating agents (ethylenediaminetetraacetic acid (EDTA, diethylenetriaminepentaacetic acid (DTPA, and hexamethylenediaminetetraacetic acid (HMDTA and heat-treated form Zn4Al2O7, to adsorb uranium(VI and ions of toxic heavy metals have been compared. Metal sorption capacities of hydrotalcite-like adsorbents have been shown to correlate with the stability of their complexes with the mentioned chelating agents in a solution. The synthesized layered double hydroxides (LDHs containing chelating agents in the interlayer space are rather efficient for sorption purification of aqueous media free from U(VI irrespective of its forms of natural abundance (including water-soluble bi- and tricarbonate forms and from heavy metal ions. [Zn4Al2(OH12]·EDTA·nH2O is recommended for practical application as one of the most efficient and inexpensive synthetic adsorbents designed for recovery of both cationic and particularly important anionic forms of U(VI and other heavy metals from aqueous media. Carbonate forms of LDHs turned out to be most efficient for recovery of Cu(II from aqueous media with pH0≥7 owing to precipitation of Cu(II basic carbonates and Cu(II hydroxides. Chromate ions are efficiently adsorbed from water only by calcinated forms of LDHs.

  12. A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

    Science.gov (United States)

    Tan, Yuan; Jing, Lijing; Ding, Yonghong; Wei, Tianxin

    2015-07-01

    This work aimed to prepare a novel double-layer structure molecularly imprinted polymer film (MIF) on the surface plasmon resonance (SPR) sensor chips for detection of testosterone in aqueous media. The film was synthesized by in-situ UV photo polymerization. Firstly, the modification of gold surface of SPR chip was performed by 1-dodecanethiol. Then double-layer MIF was generated on the 1-dodecanethiol modified gold surface. The non-modified and imprinted surfaces were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy and contact angle measurements. Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for testosterone compared to other analogues and the non-imprinted polymer film (NIF). Within the concentrations range of 1 × 10-12-1 × 10-8 mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations (R2 = 0.993). Based on a signal/noise ratio of three, the detection limit was estimated to be 10-12 mol/L. Finally, the developed MIF was successfully applied to the seawater detection of testosterone. The results in the experiments suggested that a combination of SPR sensing with MIF was a promising alternative method for detection of testosterone in aqueous media.

  13. A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

    Science.gov (United States)

    Wallett, Thomas M.

    2009-01-01

    This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements.

  14. Embedding dynamical mean-field theory for superconductivity in layered materials and heterostructures

    Science.gov (United States)

    Petocchi, Francesco; Capone, Massimo

    2016-06-01

    We study layered systems and heterostructures of s -wave superconductors by means of a suitable generalization of dynamical mean-field theory. In order to reduce the computational effort, we consider an embedding scheme in which a relatively small number of active layers is embedded in an effective potential accounting for the effect of the rest of the system. We introduce a feedback of the active layers on the embedding potential that improves on previous approaches and essentially eliminates the effects of the finiteness of the active slab allowing for cheap computation of very large systems. We extend the method to the superconducting state, and we benchmark the approach by means of simple paradigmatic examples showing some examples on how an interface affects the superconducting properties. As examples, we show that superconductivity can penetrate from an intermediate coupling superconductor into a weaker coupling one for around ten layers, and that the first two layers of a system with repulsive interaction can turn superconducting by proximity effects even when charge redistribution is inhibited.

  15. Retrieval of Parameters for Three-Layer Media with Nonsmooth Interfaces for Subsurface Remote Sensing

    Directory of Open Access Journals (Sweden)

    Yuriy Goykhman

    2012-01-01

    Full Text Available A solution to the inverse problem for a three-layer medium with nonsmooth boundaries, representing a large class of natural subsurface structures, is developed in this paper using simulated radar data. The retrieval of the layered medium parameters is accomplished as a sequential nonlinear optimization starting from the top layer and progressively characterizing the layers below. The optimization process is achieved by an iterative technique built around the solution of the forward scattering problem. The forward scattering process is formulated by using the extended boundary condition method (EBCM and constructing reflection and transmission matrices for each interface. These matrices are then combined into the generalized scattering matrix for the entire system, from which radar scattering coefficients are then computed. To be efficiently utilized in the inverse problem, the forward scattering model is simulated over a wide range of unknowns to obtain a complete set of subspace-based equivalent closed-form models that relate radar backscattering coefficients to the sought-for parameters including dielectric constants of each layer and separation of the layers. The inversion algorithm is implemented as a modified conjugate-gradient-based nonlinear optimization. It is shown that this technique results in accurate retrieval of surface and subsurface parameters, even in the presence of noise.

  16. Are socioeconomic disparities in health behavior mediated by differential media use? Test of the communication inequality theory.

    Science.gov (United States)

    Ishikawa, Yoshiki; Kondo, Naoki; Kawachi, Ichiro; Viswanath, Kasisomayajula

    2016-11-01

    Communication inequality has been offered as one potential mechanism through which social determinants influence multiple health behaviors. The purpose of this study was to examine the underlying mechanisms between communication inequality and health behaviors. Data from a nationally representative cross-sectional survey of 18,426 people aged 18 years and above in the United States were used for secondary analysis. Measures included socio-demographic characteristics, social participation (structural social capital), health media use (TV, print, and the Internet), and five health behaviors (physical activity, cigarette smoking, alcohol use, and intake of fruit and vegetable). Path analysis was performed to examine the linkages between social determinants, health media use, social participation, and social gradients in health behaviors. Path analysis revealed that socioeconomic gradients in health behaviors is mediated by: 1) inequalities in health media use; 2) disparities in social participation, which leads to differential media use; and 3) disparities in social participation that are not mediated by media use. Consistent with the theory of communication inequality, socioeconomic disparities in media use partially mediate disparities in multiple health behaviors. To address health inequalities, it is important to utilize health media to target populations with low socioeconomic statuses. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. A grounded theory of Internet and social media use by young people who use augmentative and alternative communication (AAC).

    Science.gov (United States)

    Hynan, Amanda; Goldbart, Juliet; Murray, Janice

    2015-01-01

    This paper presents a conceptual grounded theory for how young people with a diagnosis of cerebral palsy who use augmentative and alternative communication (AAC), perceive using the Internet and social media. The aims of the research were to understand and contextualise their perceptions of access and use and explore implications for self-representation and social participation; to date literature on this topic is limited. A constructivist grounded theory research approach concurrently collected and analysed interview data from 25 participants (aged 14-24 years) who use AAC and additional sources. A conceptual grounded theory was developed around an emergent core category that showed young people who use AAC have a clear desire to use the Internet and social media. This was underpinned by eight supporting categories: reported use, described support, online challenges, access technology, speech generating device (SGD) issues, self-determination, self-representation and online social ties. The conceptual grounded theory supports understanding of facilitators and challenges to use of the Internet and social media by young people with a diagnosis of cerebral palsy who use AAC. The grounded theory illustrates how the desire to use the Internet and social media is based upon perceived benefits for enriching social relationships and enhancing opportunities for self-representation and self-determination that are synonymous with identified antecedents for community-based social inclusion. Some of the participants are engaging with the Internet and social media through collaborative practice and the implications for how this phenomenon may impact on orthographic literacy and the personal care workforce are raised.

  18. A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Yuan; Jing, Lijing; Ding, Yonghong; Wei, Tianxin, E-mail: txwei@bit.edu.cn

    2015-07-01

    Highlights: • The in-situ photo-grafting polymerization method was used to prepare the polymer film. • The synthesized MIF was layer stucture film. • The MIF exhibited good imprinting effect and highly selectivity. - Abstract: This work aimed to prepare a novel double-layer structure molecularly imprinted polymer film (MIF) on the surface plasmon resonance (SPR) sensor chips for detection of testosterone in aqueous media. The film was synthesized by in-situ UV photo polymerization. Firstly, the modification of gold surface of SPR chip was performed by 1-dodecanethiol. Then double-layer MIF was generated on the 1-dodecanethiol modified gold surface. The non-modified and imprinted surfaces were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy and contact angle measurements. Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for testosterone compared to other analogues and the non-imprinted polymer film (NIF). Within the concentrations range of 1 × 10{sup −12}–1 × 10{sup −8} mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations (R{sup 2} = 0.993). Based on a signal/noise ratio of three, the detection limit was estimated to be 10{sup −12} mol/L. Finally, the developed MIF was successfully applied to the seawater detection of testosterone. The results in the experiments suggested that a combination of SPR sensing with MIF was a promising alternative method for detection of testosterone in aqueous media.

  19. Theory of multiple quantum dot formation in strained-layer heteroepitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Du, Lin; Maroudas, Dimitrios, E-mail: maroudas@ecs.umass.edu [Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003-9303 (United States)

    2016-07-11

    We develop a theory for the experimentally observed formation of multiple quantum dots (QDs) in strained-layer heteroepitaxy based on surface morphological stability analysis of a coherently strained epitaxial thin film on a crystalline substrate. Using a fully nonlinear model of surface morphological evolution that accounts for a wetting potential contribution to the epitaxial film's free energy as well as surface diffusional anisotropy, we demonstrate the formation of multiple QD patterns in self-consistent dynamical simulations of the evolution of the epitaxial film surface perturbed from its planar state. The simulation predictions are supported by weakly nonlinear analysis of the epitaxial film surface morphological stability. We find that, in addition to the Stranski-Krastanow instability, long-wavelength perturbations from the planar film surface morphology can trigger a nonlinear instability, resulting in the splitting of a single QD into multiple QDs of smaller sizes, and predict the critical wavelength of the film surface perturbation for the onset of the nonlinear tip-splitting instability. The theory provides a fundamental interpretation for the observations of “QD pairs” or “double QDs” and other multiple QDs reported in experimental studies of epitaxial growth of semiconductor strained layers and sets the stage for precise engineering of tunable-size nanoscale surface features in strained-layer heteroepitaxy by exploiting film surface nonlinear, pattern forming phenomena.

  20. Basics of quantum field theory of electromagnetic interaction processes in single-layer graphene

    Science.gov (United States)

    Hieu Nguyen, Van

    2016-09-01

    The content of this work is the study of electromagnetic interaction in single-layer graphene by means of the perturbation theory. The interaction of electromagnetic field with Dirac fermions in single-layer graphene has a peculiarity: Dirac fermions in graphene interact not only with the electromagnetic wave propagating within the graphene sheet, but also with electromagnetic field propagating from a location outside the graphene sheet and illuminating this sheet. The interaction Hamiltonian of the system comprising electromagnetic field and Dirac fermions fields contains the limits at graphene plane of electromagnetic field vector and scalar potentials which can be shortly called boundary electromagnetic field. The study of S-matrix requires knowing the limits at graphene plane of 2-point Green functions of electromagnetic field which also can be shortly called boundary 2-point Green functions of electromagnetic field. As the first example of the application of perturbation theory, the second order terms in the perturbative expansions of boundary 2-point Green functions of electromagnetic field as well as of 2-point Green functions of Dirac fermion fields are explicitly derived. Further extension of the application of perturbation theory is also discussed.

  1. Solution of transport equations in layered media with refractive index mismatch using the PN-method.

    Science.gov (United States)

    Phillips, Kevin G; Jacques, Steven L

    2009-10-01

    The PN-method is a spectral discretization technique used to obtain numerical solutions to the radiative transport equation. To the best of our knowledge, the PN-method has yet to be generalized to the case of refractive index mismatch in layered slabs used to numerically simulate skin. Our main contribution is the application of a collocation method that takes into account refractive index mismatch at layer interfaces. The stability, convergence, and accuracy of the method are established. Example calculations demonstrating the flexibility of the method are performed.

  2. 大众传媒中的霸权理论%On the Theory of Hegemony in Mass Media

    Institute of Scientific and Technical Information of China (English)

    季乃礼

    2012-01-01

    霸权理论认为大众传媒是为现有政权服务的,极力维护现有的社会秩序。霸权理论论述最为精到的是法兰克福学派学说,该学派认为大众传媒无论从内容还是形式上都导致了人们的批判能力的丧失,大众传媒操纵了民众,而政党通过操纵大众传媒影响公众。霸权理论提出后遭到了许多学者的批评,他们认为大众传媒是中立的,甚至有时是批判现有政权的。%According to the theory of hegemony,mass media serves some special interest groups,and maintains the status of current social system.Discussing it excellent in detail is Frankfort School,some scholars of this school think both content and formation of mass media resulting in the losses of people′s critical capability,and by this way,mass media has controlled the mass,and parties has influenced the public from controlling the mass media.The theory of hegemony is criticized by many scholars who think mass media are neutral,even sometimes critical in the current regime.

  3. A general polynomial solution to convection–dispersion equation using boundary layer theory

    Indian Academy of Sciences (India)

    Jiao Wang; Ming’an Shao; Laiming Huang; Xiaoxu Jia

    2017-04-01

    A number of models have been established to simulate the behaviour of solute transport due to chemical pollution, both in croplands and groundwater systems. An approximate polynomial solution to convection–dispersion equation (CDE) based on boundary layer theory has been verified for the use to describe solute transport in semi-infinite systems such as soil column. However, previous studies have only proposed low order polynomial solutions such as parabolic and cubic polynomials. This paper presents a general polynomial boundary layer solution to CDE. Comparison with exact solution suggests the prediction accuracy of the boundary layer solution varies with the order of polynomial expression and soil transport parameters. The results show that prediction accuracy increases with increasing order up to parabolic or cubic polynomial function and with no distinct relationship between accuracy and order for higher order polynomials ($n\\geqslant 3$). Comparison of two critical solute transport parameters (i.e., dispersion coefficient and retardation factor), estimated by the boundary layer solution and obtained by CXTFIT curve-fitting, shows a good agreement. The study shows that the general solution can determine the appropriate orders of polynomials for approximate CDE solutions that best describe solute concentration profiles and optimal solute transport parameters. Furthermore, the general polynomial solution to CDE provides a simple approach to solute transport problems, a criterion for choosing the right orders of polynomials for soils with different transport parameters. It is also a potential approach for estimating solute transport parameters of soils in the field.

  4. The 30-band k ṡ p theory of valley splitting in silicon thin layers

    Science.gov (United States)

    Čukarić, Nemanja A.; Partoens, Bart; Tadić, Milan Ž.; Arsoski, Vladimir V.; Peeters, F. M.

    2016-05-01

    The valley splitting of the conduction-band states in a thin silicon-on-insulator layer is investigated using the 30-band k ṡ p theory. The system composed of a few nm thick \\text{Si} layer embedded within thick SiO2 layers is analyzed. The valley split states are found to cross periodically with increasing quantum well width, and therefore the energy splitting is an oscillatory function of the quantum well width, with period determined by the wave vector K 0 of the conduction band minimum. Because the valley split states are classified by parity, the optical transition between the ground hole state and one of those valley split conduction band states is forbidden. The oscillations in the valley splitting energy decrease with electric field and with smoothing of the composition profile between the well and the barrier by diffusion of oxygen from the SiO2 layers to the Si quantum well. Such a smoothing also leads to a decrease of the interband transition matrix elements. The obtained results are well parametrized by the effective two-valley model, but are found to disagree from previous 30-band calculations. This discrepancy could be traced back to the fact that the basis for the numerical solution of the eigenproblem must be restricted to the first Brillouin zone in order to obtain quantitatively correct results for the valley splitting.

  5. Analysis of the dynamic response of layered, elastic media by means of the Fast Fourier Transform

    NARCIS (Netherlands)

    Abdelkarim, A.M.A.M.; Vrouwenvelder, A.C.W.M.

    1999-01-01

    A straightforward method is presented to calculate the three-dimensional response of layered, elastic half-spaces to a dynamic surface loading. The derivation of the method is performed in the wavenumber-frequency domain. Space-frequency domain results are subsequently obtained through the applicati

  6. Forward and inverse models of electromagnetic scattering from layered media with rough interfaces

    Science.gov (United States)

    Tabatabaeenejad, Seyed Alireza

    This work addresses the problem of electromagnetic scattering from layered dielectric structures with rough boundaries and the associated inverse problem of retrieving the subsurface parameters of the structure using the scattered field. To this end, a forward scattering model based on the Small Perturbation Method (SPM) is developed to calculate the first-order spectral-domain bistatic scattering coefficients of a two-layer rough surface structure. SPM requires the boundaries to be slightly rough compared to the wavelength, but to understand the range of applicability of this method in scattering from two-layer rough surfaces, its region of validity is investigated by comparing its output with that of a first principle solver that does not impose roughness restrictions. The Method of Moments (MoM) is used for this purpose. Finally, for retrieval of the model parameters of the layered structure using scattered field, an inversion scheme based on the Simulated Annealing method is investigated and a strategy is proposed to address convergence to local minimum.

  7. Two-dimensional linear variation displacement discontinuity method for three-layered elastic media

    CSIR Research Space (South Africa)

    Shou, KJ

    1999-09-01

    Full Text Available bonded half-planes. A three-layered elastic region is obtained by superposing two sets of bonded half-planes and subtracting one infinite plane. The advantages of this approach are: (1) it is not necessary to introduce elements at the interface, (2...

  8. Dynamic partitioning of nanoparticulate metal species between gel layers and aqueous media

    NARCIS (Netherlands)

    Veeken, van der P.L.R.

    2010-01-01

    This thesis deals with several aspects of the use of Diffusive Gradient in Thin film (DGT) and Diffusive Equilibriation in Thin film (DET) in dynamic metal speciation analysis. It has a clear focus on the properties of the diffusive gel layer, and their possible impact on metal speciation measuremen

  9. Data-driven inversion of GPR surface reflection data for lossless layered media

    NARCIS (Netherlands)

    Slob, E.C.; Wapenaar, C.P.A.

    2014-01-01

    Two wavefields can be retrieved from the measured reflection response at the surface. One is the Green’s function at a chosen virtual receiver depth level in a layered model generated by a source at the surface. The other wavefield consists of the upgoing and downgoing parts of a wavefield that focu

  10. Dynamic partitioning of nanoparticulate metal species between gel layers and aqueous media

    NARCIS (Netherlands)

    Veeken, van der P.L.R.

    2010-01-01

    This thesis deals with several aspects of the use of Diffusive Gradient in Thin film (DGT) and Diffusive Equilibriation in Thin film (DET) in dynamic metal speciation analysis. It has a clear focus on the properties of the diffusive gel layer, and their possible impact on metal speciation

  11. Reflections on Global Developments in Media Literacy Education: Bridging Theory and Practice

    Science.gov (United States)

    Hobbs, Renee; Felini, Damiano; Cappello, Gianna

    2011-01-01

    The field of media literacy education is maturing, as evidenced by the quality of presentations of research and practice shared at the 2010 World Summit on Children and Media in Karlstad. In this article, we offer our reflections on the opportunities and challenges faced by media literacy educators as we build our global community network, develop…

  12. Cultural Studies and Media Ecology: Meyrowitz's Medium Theory and Carey's Cultural Studies.

    Science.gov (United States)

    Flayhan, Donna P.

    2001-01-01

    Examines work of two communication and media studies scholars, Joshua Meyrowitz and James Carey. Suggests their studies represent media ecology with analyses of the dynamic interaction between communication, consciousness, and culture. Highlights how their work embodies a North American cultural studies approach to media studies (moving away from…

  13. Cultural Studies and Media Ecology: Meyrowitz's Medium Theory and Carey's Cultural Studies.

    Science.gov (United States)

    Flayhan, Donna P.

    2001-01-01

    Examines work of two communication and media studies scholars, Joshua Meyrowitz and James Carey. Suggests their studies represent media ecology with analyses of the dynamic interaction between communication, consciousness, and culture. Highlights how their work embodies a North American cultural studies approach to media studies (moving away from…

  14. Molecular field theory for nematic liquid crystal film with finite layers

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhi-Dong; Li Jing; Wei Huai-Peng

    2005-01-01

    The nematic liquid crystal film composed of n molecular layers is studied based upon a spatially anisotropic pair potential, which reproduces approximately the elastic free energy density. On condition that the system has perfect nematic order, as in the Lebwohl-Lasher model, the director in the film is isotropic. The effect of the temperature is investigated by means of molecular field theory. Some new results are obtained. Firstly, symmetry breaking takes place when taking account of the temperature, and the state with the director along the normal of the film has the lowest free energy. Secondly, the N-I phase transition temperature increases as an effect of finite sizes instead of decreasing as in the Lebwohl-Lasher model. Thirdly, the nematic order is induced in the layers near the surface in the isotropic phase.

  15. Multi-layer asymptotic solution for wetting fronts in porous media with exponential moisture diffusivity

    CERN Document Server

    Budd, Christopher J

    2015-01-01

    We study the asymptotic behaviour of sharp front solutions arising from the nonlinear diffusion equation \\theta_t = (D(\\theta)\\theta_x)_x, where the diffusivity is an exponential function D({\\theta}) = D_o exp(\\beta\\theta). This problem arises in the study of unsaturated flow in porous media where {\\theta} represents the liquid saturation. For the physical parameters corresponding to actual porous media, the diffusivity at the residual saturation is D(0) = D_o << 1 so that the diffusion problem is nearly degenerate. Such problems are characterised by wetting fronts that sharply delineate regions of saturated and unsaturated flow, and that propagate with a well-defined speed. Using matched asymptotic expansions in the limit of large {\\beta}, we derive an analytical description of the solution that is uniformly valid throughout the wetting front. This is in contrast with most other related analyses that instead truncate the solution at some specific wetting front location, which is then calculated as part...

  16. Finite element formulation of active constraining layer damping plate using laminate theory

    Institute of Scientific and Technical Information of China (English)

    邓年春; 邹振祝; 黄文虎

    2004-01-01

    A new finite element modeling method has been developed using laminate theory in a virlual work principle for active constraining layer damping plate. The frequency dependent modulus of viscoelastic material is described by introducing a few dissipation coordinates, known as GHM (Golla-Hughes-McTavish) method, a standard linear system with constant coefficient. The effectiveness of this method is validated by experimental model. Compared with conventional methods, this method can reduce a number of degrees of freedom and improve accuracy, provides a good model for analogous configurations.

  17. Media Consumption on the World Wide Web: Integrating Theories of Media Choice and Global Media Flows to Explain Global Cultural Consumption

    Science.gov (United States)

    Taneja, Harsh

    2014-01-01

    The cross border availability of media content has raised speculations that content preferences would largely drive audience choices. In such a scenario, technologies and institutional structures would primarily shape patterns of global cultural consumption, sweeping away old allegiances based on cultural traits such as language and geography. On…

  18. Z-scan theory for nonlocal nonlinear media with simultaneous nonlinear refraction and nonlinear absorption.

    Science.gov (United States)

    Rashidian Vaziri, Mohammad Reza

    2013-07-10

    In this paper, the Z-scan theory for nonlocal nonlinear media has been further developed when nonlinear absorption and nonlinear refraction appear simultaneously. To this end, the nonlinear photoinduced phase shift between the impinging and outgoing Gaussian beams from a nonlocal nonlinear sample has been generalized. It is shown that this kind of phase shift will reduce correctly to its known counterpart for the case of pure refractive nonlinearity. Using this generalized form of phase shift, the basic formulas for closed- and open-aperture beam transmittances in the far field have been provided, and a simple procedure for interpreting the Z-scan results has been proposed. In this procedure, by separately performing open- and closed-aperture Z-scan experiments and using the represented relations for the far-field transmittances, one can measure the nonlinear absorption coefficient and nonlinear index of refraction as well as the order of nonlocality. Theoretically, it is shown that when the absorptive nonlinearity is present in addition to the refractive nonlinearity, the sample nonlocal response can noticeably suppress the peak and enhance the valley of the Z-scan closed-aperture transmittance curves, which is due to the nonlocal action's ability to change the beam transverse dimensions.

  19. The Electrodynamics of Inhomogeneous Rotating Media and the Abraham and Minkowski Tensors I: General Theory

    CERN Document Server

    Goto, Shin-itiro; Walton, Timothy J

    2010-01-01

    This is paper I of a series of two papers, offering a self-contained analysis of the role of electromagnetic stress-energy-momentum tensors in the classical description of continuous polarizable perfectly insulating media. While acknowledging the primary role played by the total stress-energy-momentum tensor on spacetime, we argue that it is meaningful and useful in the context of covariant constitutive theory to assign preferred status to particular parts of this total tensor, when defined with respect to a particular splitting. The notion of a force density that arises from the divergence of these tensors is strictly defined relative to some inertial property of the medium. Consistency with the laws of Newtonian continuum mechanics demands that the total force density on any element of a medium be proportional to the local linear acceleration field of that element in an inertial frame and must also arise as part of the divergence of the total stress-energy-momentum tensor. In this paper we explore how elect...

  20. A porous media theory for characterization of membrane blood oxygenation devices

    Science.gov (United States)

    Sano, Yoshihiko; Adachi, Jun; Nakayama, Akira

    2013-07-01

    A porous media theory has been proposed to characterize oxygen transport processes associated with membrane blood oxygenation devices. For the first time, a rigorous mathematical procedure based a volume averaging procedure has been presented to derive a complete set of the governing equations for the blood flow field and oxygen concentration field. As a first step towards a complete three-dimensional numerical analysis, one-dimensional steady case is considered to model typical membrane blood oxygenator scenarios, and to validate the derived equations. The relative magnitudes of oxygen transport terms are made clear, introducing a dimensionless parameter which measures the distance the oxygen gas travels to dissolve in the blood as compared with the blood dispersion length. This dimensionless number is found so large that the oxygen diffusion term can be neglected in most cases. A simple linear relationship between the blood flow rate and total oxygen transfer rate is found for oxygenators with sufficiently large membrane surface areas. Comparison of the one-dimensional analytic results and available experimental data reveals the soundness of the present analysis.

  1. Reconstruction of annular bi-layered media in cylindrical waveguide section

    CERN Document Server

    Eriksson, Anders; Beilina, Larisa

    2016-01-01

    A radial transverse resonance model for two cylindrical concentric layers with different complex dielectric constants is presented. An inverse problem with four unknowns - 3 physical material parameters and one dimensional dielectric layer thickness parameter- is solved by employing TE110 and TE210 modes with different radial field distribution. First a Newton-Raphson algorithm is used to solve a least square problem with a Lorentzian function (as resonance model and "measured" data generator). Then found resonance frequencies and quality factors are used in a second inverse Newton-Raphson algorithm that solves four transverse resonance equations in order to get four unknown parameters. The use of TE110 and TE210 models offers one dimensional radial tomographic capability. An open ended coax quarter-wave resonator is added to the sensor topology, and the effect on the convergence is investigated.

  2. N-doped graphitic layer encased cobalt nanoparticles as efficient oxygen reduction catalysts in alkaline media

    Science.gov (United States)

    Han, Ce; Bo, Xiangjie; Zhang, Yufan; Li, Mian; Nsabimana, Anaclet; Guo, Liping

    2015-03-01

    Nitrogen doped graphitic layer encased cobalt (N-C@Co) nanoparticles, as novel non-precious-metal catalysts for the oxygen reduction reaction (ORR), were fabricated by a facile method using cyanamide and cobalt nitrate as precursors. The N-C@Co catalysts exhibited comparable catalytic performance, better stability and improved methanol tolerance towards the ORR than those of the commercial Pt/C catalyst.Nitrogen doped graphitic layer encased cobalt (N-C@Co) nanoparticles, as novel non-precious-metal catalysts for the oxygen reduction reaction (ORR), were fabricated by a facile method using cyanamide and cobalt nitrate as precursors. The N-C@Co catalysts exhibited comparable catalytic performance, better stability and improved methanol tolerance towards the ORR than those of the commercial Pt/C catalyst. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07571d

  3. The three-layered mismatched media diffusion equation in frequency domain

    Science.gov (United States)

    Wang, Xichang; Wang, Shumei; Meng, Zhaokun; Yang, Shangming

    2006-09-01

    Near-IR radiation has great potential in medical diagnosis and therapy because of the non-invasive nature of light and the selectively poisonous effect to tumors of photodynarnic treatment. Therefore, Near-IR light propagation in highly scattering biological tissue must be understudied for basic research and clinical application of biomedical optics. A tissue is multi-layered mismatched medium, but many investigators only study the diffusion equation of matched medium. they take the tissue as the same refractive index. In order to understand the light transport in tissue, We analyze the diffusion of photons three-layered mismatched medium and set up the solution of Green's function in frequency domain, we employ the extrapolated boundary condition to set up a solution of the diffusion equation. At the same time, we utilize the diffuse equation to calculate the phase in different situation

  4. Neural network model for the efficient calculation of Green's functions in layered media

    CERN Document Server

    Soliman, E A; El-Gamal, M A; 10.1002/mmce.10066

    2003-01-01

    In this paper, neural networks are employed for fast and efficient calculation of Green's functions in a layered medium. Radial basis function networks (RBFNs) are effectively trained to estimate the coefficients and the exponents that represent a Green's function in the discrete complex image method (DCIM). Results show very good agreement with the DCIM, and the trained RBFNs are very fast compared with the corresponding DCIM. (23 refs).

  5. Split-step finite-difference time-domain method with perfectly matched layers for efficient analysis of two-dimensional photonic crystals with anisotropic media.

    Science.gov (United States)

    Singh, Gurpreet; Tan, Eng Leong; Chen, Zhi Ning

    2012-02-01

    This Letter presents a split-step (SS) finite-difference time-domain (FDTD) method for the efficient analysis of two-dimensional (2-D) photonic crystals (PhCs) with anisotropic media. The proposed SS FDTD method is formulated with perfectly matched layer boundary conditions and caters for inhomogeneous anisotropic media. Furthermore, the proposed method is derived using the efficient SS1 splitting formulas with simpler right-hand sides that are more efficient and easier to implement. A 2-D PhC cavity with anisotropic media is used as an example to validate the efficiency of the proposed method.

  6. An Estimation of Turbulent Kinetic Energy and Energy Dissipation Rate Based on Atmospheric Boundary Layer Similarity Theory

    Science.gov (United States)

    Han, Jongil; Arya, S. Pal; Shaohua, Shen; Lin, Yuh-Lang; Proctor, Fred H. (Technical Monitor)

    2000-01-01

    Algorithms are developed to extract atmospheric boundary layer profiles for turbulence kinetic energy (TKE) and energy dissipation rate (EDR), with data from a meteorological tower as input. The profiles are based on similarity theory and scalings for the atmospheric boundary layer. The calculated profiles of EDR and TKE are required to match the observed values at 5 and 40 m. The algorithms are coded for operational use and yield plausible profiles over the diurnal variation of the atmospheric boundary layer.

  7. Effects of electrolytic composition on the electric double-layer capacitance at smooth-surface carbon electrodes in organic media

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In-Tae; Egashira, Minato; Yoshimoto, Nobuko [Graduate School of Science and Engineering, Yamaguchi University, 2-16-1, Tokiwadai, Ube, 755-8611 (Japan); Morita, Masayuki, E-mail: morita@yamaguchi-u.ac.j [Graduate School of Science and Engineering, Yamaguchi University, 2-16-1, Tokiwadai, Ube, 755-8611 (Japan)

    2010-09-01

    As a fundamental research on the optimization of electrolyte composition in practical electrochemical capacitor device, double-layer capacitance at Glassy Carbon (GC) and Boron-doped Diamond (BDD), as typical smooth-surface carbon electrodes, has been studied as a function of the electrolyte composition in organic media. Specific capacitance (differential capacitance: F cm{sup -2}) determined by an AC impedance method, in which no contribution of mass-transport effects is included, corresponded well to integrated capacitance evaluated by conventional cyclic voltammetry. The specific capacitance at the GC electrode varied with polarized potential and showed clear PZC (potential of zero charge), while the potential dependence of the capacitance at BDD was very small. The effects of the solvent and the electrolytic salt on the capacitance behavior were common for both electrodes. That is, the sizes of the solvent molecule and the electrolytic ion (cation) strongly affected the capacitance at these smooth-surface carbon electrodes.

  8. Thin layered drawing media probed by THz time-domain spectroscopy

    CERN Document Server

    Tasseva, J; Bartolini, P; Striova, J; Fontana, R; Torre, R

    2016-01-01

    Dry and wet drawing materials were investigated by THz time-domain spectroscopy in transmission mode. Carbon-based and iron-gall inks have been studied, some prepared following ancient recipes and others using current synthetic materials; a commercial ink was studied as well. We measured the THz signals on thin film of liquid inks deposited on polyethylene pellicles, comparing the results with the thick pellets of dried inks blended with polyethylene powder. This study required the implementation of a new experimental method and data analysis procedure able to provide a reliable extraction of the material transmission parameters from a structured sample composed of thin layers, down to thickness of few tens of micrometers. THz measurements on thin ink layers enabled the determination of both the absorption and the refractive index in an absolute scale in the 0.1 - 3 THz range, as well as the layer thickness. THz spectroscopic features of a paper sheet dyed by one of the iron-gall inks were also investigated. ...

  9. Effects of Rotation and Gravity Field on Surface Waves in Fibre-Reinforced Thermoelastic Media under Four Theories

    Directory of Open Access Journals (Sweden)

    A. M. Abd-Alla

    2013-01-01

    Full Text Available Estimation is done to investigate the gravitational and rotational parameters effects on surface waves in fibre-reinforced thermoelastic media. The theory of generalized surface waves has been firstly developed and then it has been employed to investigate particular cases of waves, namely, Stoneley waves, Rayleigh waves, and Love waves. The analytical expressions for surface waves velocity and attenuation coefficient are obtained in the physical domain by using the harmonic vibrations and four thermoelastic theories. The wave velocity equations have been obtained in different cases. The numerical results are given for equation of coupled thermoelastic theory (C-T, Lord-Shulman theory (L-S, Green-Lindsay theory (G-L, and the linearized (G-N theory of type II. Comparison was made with the results obtained in the presence and absence of gravity, rotation, and parameters for fibre-reinforced of the material media. The results obtained are displayed by graphs to clear the phenomena physical meaning. The results indicate that the effect of gravity, rotation, relaxation times, and parameters of fibre-reinforced of the material medium is very pronounced.

  10. Light Condensation and Localization in Disordered Photonic Media: Theory and Large Scale ab initio Simulations

    KAUST Repository

    Toth, Laszlo Daniel

    2013-05-07

    Disordered photonics is the study of light in random media. In a disordered photonic medium, multiple scattering of light and coherence, together with the fundamental principle of reciprocity, produce a wide range of interesting phenomena, such as enhanced backscattering and Anderson localization of light. They are also responsible for the existence of modes in these random systems. It is known that analogous processes to Bose-Einstein condensation can occur in classical wave systems, too. Classical condensation has been studied in several contexts in photonics: pulse formation in lasers, mode-locking theory and coherent emission of disordered lasers. All these systems have the common theme of possessing a large ensemble of waves or modes, together with nonlinearity, dispersion or gain. In this work, we study light condensation and its connection with light localization in a disordered, passive dielectric medium. We develop a theory for the modes inside the disordered resonator, which combines the Feshbach projection technique with spin-glass theory and statistical physics. In particular, starting from the Maxwell’s equations, we map the system to a spherical p-spin model with p = 2. The spins are replaced by modes and the temperature is related to the fluctuations in the environment. We study the equilibrium thermodynamics of the system in a general framework and show that two distinct phases exist: a paramagnetic phase, where all the modes are randomly oscillating and a condensed phase, where the energy condensates on a single mode. The thermodynamic quantities can be explicitly interpreted and can also be computed from the disorder-averaged time domain correlation function. We launch an ab initio simulation campaign using our own code and the Shaheen supercomputer to test the theoretical predictions. We construct photonic samples of varying disorder and find computationally relevant ways to obtain the thermodynamic quantities. We observe the phase transition

  11. Multilevel Multipole-Free Fast Algorithm For Electromagnetic Scattering Problems In Layered Media

    Science.gov (United States)

    2006-09-29

    outgoing-to-outgoing ( O2O ) shifting matrices that translate a child group to a parent group, incoming-to-incoming (I2I) shifting matrices that translate a...also O2I matrices for the layered, or stratified, medium contribution that are denoted as O2I-SM translation matrices. The O2O and I2I matrices are...the reader is referred to the references for more details on interpolation, outgoing-to- outgoing ( O2O ), incoming-to-incoming (I2I) matrices, and

  12. Lubrication theory applied to the convergent flows of two stacked liquid layers

    Energy Technology Data Exchange (ETDEWEB)

    Gratton, Julio [INFIP-CONICET, Dpto. de Fisica, FCEyN, UBA, Ciudad Universitaria, Pab. I, 1428 Buenos Aires (Argentina); Perazzo, Carlos Alberto, E-mail: jgratton@tinfip.lfp.uba.ar, E-mail: perazzo@favaloro.edu.ar [Universidad Favaloro and CONICET, Solis 453, 1078 Buenos Aires (Argentina)

    2011-05-01

    With the aim of describing the mountain building process, we have previously applied the lubrication approximation to obtain the evolution equations of the problem of two stacked layers of viscous fluids with different densities and different viscosities. The lubrication approximation is a perturbation method where the small parameter is the aspect ratio (thickness/lenght) of the current. This approximation is widely used to study the slow flow of one layer of a viscous fluid, but it is not well known under which conditions it can be applied in more general settings. Here we analyze in detail the assumptions needed to apply the lubrication theory to study the flow of two stacked viscous fluid layers. We employ the same perturbation method and we found that, besides the usual conditions (low Reynolds number and gentle slope), we must require that the viscosity and density ratios are of the order of unity. These requirements determine the range of validity of the equations of our model of the mountain building.

  13. Non-blind acoustic invisibility by dual layers of homogeneous single-negative media

    Science.gov (United States)

    Gao, He; Zhu, Yi-Fan; Fan, Xu-Dong; Liang, Bin; Yang, Jing; Cheng, Jian-Chun

    2017-02-01

    Non-blind invisibility cloaks allowing the concealed object to sense the outside world have great application potentials such as in high-precision sensing or underwater camouflage. However the existing designs based on coordinate transformation techniques need complicated spatially-varying negative index or intricate multi-layered configurations, substantially increasing the difficulty in practical realization. Here we report on the non-blind acoustic invisibility for a circular object in free space with simple distribution of cloak parameters. The mechanism is that, instead of utilizing the transformation acoustics technique, we develop the analytical formulae for fast prediction of the scattering from the object and then use an evolutionary optimization to retrieve the desired cloak parameters for minimizing the scattered field. In this way, it is proven possible to break through the fundamental limit of complementary condition that must be satisfied by the effective parameters of the components in transformation acoustics-based cloaks. Numerical results show that the resulting cloak produces a non-bflind invisibility as perfect as in previous designs, but only needs two layers with homogenous single-negative parameters. With full simplification in parameter distribution and broken symmetry in complementary relationship, our scheme opens new route to free-space non-blind invisibility, taking a significant step towards real-world application of cloaking devices.

  14. Cellulose acetate layer effect toward aluminium corrosion rate in hydrochloric acid media

    Science.gov (United States)

    Andarany, K. S.; Sagir, A.; Ahmad, A.; Deni, S. K.; Gunawan, W.

    2017-09-01

    Corrosion occurs due to the oxidation and reduction reactions between the material and its environment. The oxidation reaction defined as reactions that produce electrons and reduction is between two elements that bind the electrons. Corrosion cannot be inevitable in life both within the industry and household. Corrosion cannot eliminate but can be control. According to the voltaic table, Aluminum is a metal that easily corroded. This study attempts to characterize the type of corrosion by using a strong acid media (HCl). Experiment using a strong acid (HCl), at a low concentration that occurs is pitting corrosion, whereas at high concentrations that occurs is corrosion erosion. One of prevention method is by using a coating method. An efforts are made to slow the rate of corrosion is by coating the metal with “cellulose acetate” (CA). cellulose acetate consisted of cellulose powder dissolved in 99% acetic acid, and then applied to the aluminum metal. Soaking experiments using hydrochloric acid, cellulose acetate is able to slow down the corrosion rate of 47 479%.

  15. Theory and Application of Characteristic Finite Element Domain Decomposition Procedures for Coupled System of Dynamics of Fluids in Porous Media

    Institute of Scientific and Technical Information of China (English)

    Yi-rang Yuan

    2007-01-01

    For a coupled system of multiplayer dynamics of fluids in porous media,the characteristic finite element domain decomposition procedures applicable to parallel arithmetic are put forward.Techniques such as calculus of variations,domain decomposition,characteristic method,negative norm estimate,energy method and the theory of prior estimates are adopted.Optimal order estimates in L2 norm are derived for the error in the approximate solution.

  16. The theorization of social co-ordinations in differentiated societies: the theory of generalized symbolic media in Parsons, Luhmann and Habermas.

    Science.gov (United States)

    Chernilo, Daniel

    2002-09-01

    The problem of the differentiation of societies is at the core of the sociological imagination about the rise of modernity. In postwar sociology, T. Parsons developed the theory of generalized symbolic media in the mid-1960s to tackle, theoretically and historically, the issue of differentiation. According to him, the interchange media are defined as resources oriented to exchange processes between the subsystems of the social system. Starting with money, Parsons argues that the remaining media (power, influence, and value-commitments) have a set of characteristics defined as common properties for all media. After this first formulation, contemporary theorists such as Niklas Luhmann and Jürgen Habermas have developed and modified the Parsonian theory: Luhmann rejects the idea of interchange and proposes the use of communication; Habermas distinguishes between steering and communication media. In all three cases, the focus of the theory is on the characterization of the strongest dynamics of social co-ordination present in differentiated societies. A major result of these developments is the inclusion of new dimensions on which to conceive the properties of media, not only those of money but also language. Beyond differences, then, it is proposed that there is only one theory of generalized symbolic media which can be understood as a progressive research programme, in Lakatos' terms. Finally, the hand-in-hand evolution between the theory of media and Habermas' and Luhmann's re-conceptualizations on societal differentiation in contemporary societies will also be revealed.

  17. Ginzburg-Landau theory of the superheating field anisotropy of layered superconductors

    Science.gov (United States)

    Liarte, Danilo B.; Transtrum, Mark K.; Sethna, James P.

    2016-10-01

    We investigate the effects of material anisotropy on the superheating field of layered superconductors. We provide an intuitive argument both for the existence of a superheating field, and its dependence on anisotropy, for κ =λ /ξ (the ratio of magnetic to superconducting healing lengths) both large and small. On the one hand, the combination of our estimates with published results using a two-gap model for MgB2 suggests high anisotropy of the superheating field near zero temperature. On the other hand, within Ginzburg-Landau theory for a single gap, we see that the superheating field shows significant anisotropy only when the crystal anisotropy is large and the Ginzburg-Landau parameter κ is small. We then conclude that only small anisotropies in the superheating field are expected for typical unconventional superconductors near the critical temperature. Using a generalized form of Ginzburg Landau theory, we do a quantitative calculation for the anisotropic superheating field by mapping the problem to the isotropic case, and present a phase diagram in terms of anisotropy and κ , showing type I, type II, or mixed behavior (within Ginzburg-Landau theory), and regions where each asymptotic solution is expected. We estimate anisotropies for a number of different materials, and discuss the importance of these results for radio-frequency cavities for particle accelerators.

  18. Density Functional Theory Study of Atomic Layer Deposition of Zinc Oxide on Graphene.

    Science.gov (United States)

    Ali, Amgad Ahmed; Hashim, Abdul Manaf

    2015-12-01

    The dissociation of zinc ions (Zn(2+)) from vapor-phase zinc acetylacetonate, Zn(C5H7O2)2, or Zn(acac)2 and its adsorption onto graphene oxide via atomic layer deposition (ALD) were studied using a quantum mechanics approach. Density functional theory (DFT) was used to obtain an approximate solution to the Schrödinger equation. The graphene oxide cluster model was used to represent the surface of the graphene film after pre-oxidation. In this study, the geometries of reactants, transition states, and products were optimized using the B3LYB/6-31G** level of theory or higher. Furthermore, the relative energies of the various intermediates and products in the gas-phase radical mechanism were calculated at the B3LYP/6-311++G** and MP2/6-311 + G(2df,2p) levels of theory. Additionally, a molecular orbital (MO) analysis was performed for the products of the decomposition of the Zn(acac)2 complex to investigate the dissociation of Zn(2+) and the subsequent adsorption of H atoms on the C5H7O2 cluster to form acetylacetonate enol. The reaction energies were calculated, and the reaction mechanism was accordingly proposed. A simulation of infrared (IR) properties was performed using the same approach to support the proposed mechanism via a complete explanation of bond forming and breaking during each reaction step.

  19. Longitudinal acoustic waves in layered media: Comparative study of Raman scattering and reflection delay time

    Energy Technology Data Exchange (ETDEWEB)

    El Boudouti, E H; Zelmat, R; Bailich, R [LDOM, Departement de Physique, Faculte des Sciences, Universite Mohamed I, 60000 Oujda (Morocco); Hassouani, Y El [Universite de Bordeaux, Laboratoire de Mecanique Physique, Talence F-33405 (France); Djafari-Rouhani, B, E-mail: elboudouti@yahoo.f [Institut d' Electronique, de Microelectronique et de Nanotechnologie, UMR CNRS 8520, UFR de Physique, Universite de Lille 1, 59655 Villeneuve d' Ascq (France)

    2010-03-01

    Using a Green's function method, we present a theoretical analysis of the propagation of acoustic waves in multilayer structures. The structure studied consists of a finite superlattice (SL) made of a periodic repetition of N unit cells deposited on a substrate. Such a structure exhibits extended modes constituting the allowed bands separated by forbidden bands where localized modes associated to free surfaces, defect layers, ... may exist. These modes can be observed either by Raman scattering when an incident light is launched from vacuum towards the multilayer, or by the reflection delay time when an incident acoustic wave is launched from the substrate. Specific applications of our results are given for some available experiments in the literature (e.g., Si/Ge{sub x}Si{sub 1-x}, GaSb-AlSb) and a good agreement has been obtained between our theoretical results and the experimental data.

  20. Fluid Effects on Shear for Seismic Waves in Finely Layered Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J G

    2004-07-22

    Although there are five effective shear moduli for any layered VTI medium, one and only one effective shear modulus of the layered system (namely the uniaxial shear) contains all the dependence of pore fluids on the elastic or poroelastic constants that can be observed in vertically polarized shear waves. Pore fluids can increase the magnitude the shear energy stored in this modulus by an amount that ranges from the smallest to the largest effective shear moduli of the VTI system. But, since there are five shear moduli in play, the overall increase in shear energy due to fluids is reduced by a factor of about 5 in general. We can therefore give definite bounds on the maximum increase of overall shear modulus, being about 20% of the allowed range as liquid is fully substituted for gas. An attendant increase of density (depending on porosity and fluid density) by approximately 5 to 10% decreases the shear wave speed and, thereby, partially offsets the effect of this shear modulus increase. The final result is an increase of shear wave speed on the order of 5 to 10%. This increase is shown to be possible under most favorable circumstances - i.e. when the shear modulus fluctuations are large (resulting in strong anisotropy) and the medium behaves in an undrained fashion due to fluid trapping. At frequencies higher than seismic (such as sonic and ultrasonic waves for well-logging or laboratory experiments), resulting short response times also produce the requisite undrained behavior and, therefore, fluids also affect shear waves at high frequencies by increasing rigidity.

  1. Silver-Copper Nanoalloy Catalyst Layer for Bifunctional Air Electrodes in Alkaline Media.

    Science.gov (United States)

    Wu, Xiaoqiang; Chen, Fuyi; Jin, Yachao; Zhang, Nan; Johnston, Roy L

    2015-08-19

    A carbon-free and binder-free catalyst layer composed of a Ag-Cu nanoalloy on Ni foam was used as the air cathode in a zinc-air battery for the first time. The Ag-Cu catalyst was prepared using pulsed laser deposition. The structures of the catalysts were found to consist of crystalline Ag-Cu nanoalloy particles with an average size of 2.58 nm embedded in amorphous Cu films. As observed in the X-ray photoelectron spectra, the Ag 3d core levels shifted to higher binding energies, whereas the Cu 2p core levels shifted to lower binding energies, indicating alloying of the silver and copper. Rotating disk electrode measurements indicated that the oxygen reduction reaction (ORR) proceeded through a four-electron pathway on the Ag50Cu50 and Ag90Cu10 nanoalloy catalysts in alkaline solution. Moreover, the catalytic activity of Ag50Cu50 in the ORR is more efficient than that of Ag90Cu10. By performing charge and discharge cycling measurements, the Ag50Cu50 catalyst layer was confirmed to have a maximum power density of approximately 86.3 mW cm(-2) and an acceptable cell voltage at 0.863 V for current densities up to 100 mA cm(-2) in primary zinc-air batteries. In addition, a round-trip efficiency of approximately 50% at a current density of 20 mA cm(-2) was also obtained in the test.

  2. Media and Youth Development: An Overview of Issues, Theory, and Research

    Directory of Open Access Journals (Sweden)

    Christine McCauley Ohannessian

    2014-03-01

    Full Text Available The homes of today’s youth are filled with a variety of media options, ranging from televisions (71% and video game consoles (50% in their bedrooms to portable handheld devices (e.g., iPods/mp3 players, 76% and cell phones (71% that can accompany youth wherever they go. Of course, youth also have access to centralized media found in homes, such as televisions (99% of homes and computers with and without Internet access (93% and 84% of homes, respectively. Not surprisingly, youth consume media for about 7.5 hours per day, much of which involves using more than one media at the same time (i.e., multitasking, with adolescents consuming significantly more media than children (Lenhart, 2012; Rideout, Foehr, & Roberts, 2010.

  3. Theory of wave propagation in partially saturated double-porosity rocks: a triple-layer patchy model

    Science.gov (United States)

    Sun, Weitao; Ba, Jing; Carcione, José M.

    2016-04-01

    Wave-induced local fluid flow is known as a key mechanism to explain the intrinsic wave dissipation in fluid-saturated rocks. Understanding the relationship between the acoustic properties of rocks and fluid patch distributions is important to interpret the observed seismic wave phenomena. A triple-layer patchy (TLP) model is proposed to describe the P-wave dissipation process in a double-porosity media saturated with two immiscible fluids. The double-porosity rock consists of a solid matrix with unique host porosity and inclusions which contain the second type of pores. Two immiscible fluids are considered in concentric spherical patches, where the inner pocket and the outer sphere are saturated with different fluids. The kinetic and dissipation energy functions of local fluid flow (LFF) in the inner pocket are formulated through oscillations in spherical coordinates. The wave propagation equations of the TLP model are based on Biot's theory and the corresponding Lagrangian equations. The P-wave dispersion and attenuation caused by the Biot friction mechanism and the local fluid flow (related to the pore structure and the fluid distribution) are obtained by a plane-wave analysis from the Christoffel equations. Numerical examples and laboratory measurements indicate that P-wave dispersion and attenuation are significantly influenced by the spatial distributions of both, the solid heterogeneity and the fluid saturation distribution. The TLP model is in reasonably good agreement with White's and Johnson's models. However, differences in phase velocity suggest that the heterogeneities associated with double-porosity and dual-fluid distribution should be taken into account when describing the P-wave dispersion and attenuation in partially saturated rocks.

  4. On Contemporary Western Media Critical Theory%当代西方媒介批判理论疏略

    Institute of Scientific and Technical Information of China (English)

    李勇

    2013-01-01

    There is no denying the fact that media is an unavoidable topic investigating contemporary society and culture .Con-temporary western media critical theory has four main schools: Germany, France, United Kingdom and North America.Its research topic mainly focuses on media, context and audience, and its scientific attitudes conclude optimism, pessimism and impersonalism. Its research methods concern with Semeiology, Marxism, Sociology, Feminism, Depth Psychology, and so on.There are some fore-front and hot topics such as subject research, audience theory, ideology theory etc.in western media critical theory in the recent years.There are many important values in Contemporary western critical media theory, and it is deserved to study deeply.%媒介批判理论是审视媒介文化现象及媒介文化问题的重要的和独特的视角。进入西方媒介批判理论的历史现场,大致可梳理出德、英、法、北美四大理论谱系;其研究领域多围绕机构、文本、受众三方面展开;研究态度则有乐观派、悲观派和客观派之别;方法上多以符号学、马克思主义、社会学、女性主义、精神分析批评等为指导;近些年,围绕主体、受众、权力、意识形态、终结论等焦点问题的理论相对集中。西方媒介批判理论涉及问题很多,理论和现实意义重要,值得深入研究。

  5. Application of coupled mode theory on radiative heat transfer between layered Lorentz materials

    Science.gov (United States)

    Lin, Chungwei; Wang, Bingnan; Teo, Koon Hoo

    2017-05-01

    The coupled mode theory (CMT) provides a simple and clear framework to analyze the radiation energy exchange between reservoirs. We apply CMT to analyze the radiative heat transfer between layered Lorentz materials whose dielectric functions can be approximated by the Lorentz oscillator model. By comparing the transmissivity computed by the exact solution to that computed by CMT, we find that CMT generally gives a good approximation for this class of materials. The biggest advantage of CMT analysis, in our opinion, is that only the (complex) resonant energies are needed to obtain the radiation energy transfer; the knowledge of the spatial profile of resonances is not required. Several issues, including how to choose the resonant modes, what these modes represent, and the limitation of this method, are discussed. Finally, we also apply the CMT method to the electronic systems, demonstrating the generality of this formalism.

  6. Hydraulic theory for a debris flow supported on a collisional shear layer.

    Science.gov (United States)

    Jenkins, J. T.; Askari, E.

    1999-09-01

    We consider a heap of grains driven by gravity down an incline. We assume that the heap is supported at its base on a relatively thin carpet of intensely sheared, highly agitated grains that interact through collisions. We adopt the balance laws, constitutive relations, and boundary conditions of a kinetic theory for dense granular flows and determine the relationship between the shear stress, normal stress, and relative velocity of the boundaries in the shear layer in an analysis of a steady shearing flow between identical bumpy boundaries. This relationship permits us to close the hydraulic equations governing the evolution of the shape of the heap and the velocity distribution at its base. We integrate the resulting equations numerically for typical values of the parameters for glass spheres. (c) 1999 American Institute of Physics.

  7. Group Theory Analysis of Free Convective Boundary—Layer Behavior at a Stretching Surface

    Institute of Scientific and Technical Information of China (English)

    JunmeiShi; XueziXu; 等

    1995-01-01

    In the present study,free convection and heat transfer behavior of electrically conducting fluid in the boundary layer over a vertical continuously stretching surface is investigated.The effects of free convection,magnetic field,suction/blowing at the surface and the stretching speed of the surface on the flow and heat transfer characteristics are considered.By applying one-parametric group theory to analysis of the problem,a similarity solution is found.The governing equations of continuity,momentum and energy are solved numerically by a fourth-order Runge-Kutta scheme.The numerical results.which are obtained for the flow and heat transfer characteristics,reveal the influences of the parameters.

  8. A theory for modeling ground-water flow in heterogeneous media

    Science.gov (United States)

    Cooley, Richard L.

    2004-01-01

    Construction of a ground-water model for a field area is not a straightforward process. Data are virtually never complete or detailed enough to allow substitution into the model equations and direct computation of the results of interest. Formal model calibration through optimization, statistical, and geostatistical methods is being applied to an increasing extent to deal with this problem and provide for quantitative evaluation and uncertainty analysis of the model. However, these approaches are hampered by two pervasive problems: 1) nonlinearity of the solution of the model equations with respect to some of the model (or hydrogeologic) input variables (termed in this report system characteristics) and 2) detailed and generally unknown spatial variability (heterogeneity) of some of the system characteristics such as log hydraulic conductivity, specific storage, recharge and discharge, and boundary conditions. A theory is developed in this report to address these problems. The theory allows construction and analysis of a ground-water model of flow (and, by extension, transport) in heterogeneous media using a small number of lumped or smoothed system characteristics (termed parameters). The theory fully addresses both nonlinearity and heterogeneity in such a way that the parameters are not assumed to be effective values. The ground-water flow system is assumed to be adequately characterized by a set of spatially and temporally distributed discrete values, ?, of the system characteristics. This set contains both small-scale variability that cannot be described in a model and large-scale variability that can. The spatial and temporal variability in ? are accounted for by imagining ? to be generated by a stochastic process wherein ? is normally distributed, although normality is not essential. Because ? has too large a dimension to be estimated using the data normally available, for modeling purposes ? is replaced by a smoothed or lumped approximation y?. (where y is a

  9. Breaking news dissemination in the media via propagation behavior based on complex network theory

    Science.gov (United States)

    Liu, Nairong; An, Haizhong; Gao, Xiangyun; Li, Huajiao; Hao, Xiaoqing

    2016-07-01

    The diffusion of breaking news largely relies on propagation behaviors in the media. The tremendous and intricate propagation relationships in the media form a complex network. An improved understanding of breaking news diffusion characteristics can be obtained through the complex network research. Drawing on the news data of Bohai Gulf oil spill event from June 2011 to May 2014, we constructed a weighted and directed complex network in which media are set as nodes, the propagation relationships as edges and the propagation times as the weight of the edges. The primary results show (1) the propagation network presents small world feature, which means relations among media are close and breaking news originating from any node can spread rapidly; (2) traditional media and official websites are the typical sources for news propagation, while business portals are news collectors and spreaders; (3) the propagation network is assortative and the group of core media facilities the spread of breaking news faster; (4) for online media, news originality factor become less important to propagation behaviors. This study offers a new insight to explore information dissemination from the perspective of statistical physics and is beneficial for utilizing the public opinion in a positive way.

  10. Comparison of macro- and microscopic theories describing multicomponent mass transport in microporous media

    NARCIS (Netherlands)

    Benes, Nieck Edwin; Verweij, H.

    2000-01-01

    A detailed discussion is presented of three well-known macroscopic theories for describing the mass transport behavior of multicomponent mixtures; these include Fick's law, the Onsager theory of irreversible thermodynamics, and the Maxwell-Stefan theory. The merits and drawbacks of these theories ar

  11. Monitoring the Information Environment: The Theory and Measurement of Media Performance%监测信息环境的质量:媒体表现的理论及测量

    Institute of Scientific and Technical Information of China (English)

    刘海龙

    2012-01-01

    This paper reviewed the concept evolution, research tradition and theories of media performance and suggested a new theory frame of media performance evaluation which is to fit Chinese context. This index includes three layers, which are professionalism, variety and order. The media performance evaluation will function to stimulate the media to improve the quality, to provide solid evident for both policy-making and academic research.%媒体表现研究是以公共利益为基本价值取向,通过经验性的内容分析,系统、全面地评估媒体内容的质量。本文在对媒体表现的概念演变、研究传统和理论进行梳理之后,结合中国的实际,认为中国的媒体表现评估指标应该包括三个层次:专业、多元和秩序。媒体表现研究可以促进媒体改进质量,有助于媒体政策的科学决策,也可以为学术研究提供基础数据。

  12. Quantum theory for the nanoscale propagation of light through stacked thin film layers

    Science.gov (United States)

    Forbes, Kayn A.; Williams, Mathew D.; Andrews, David L.

    2016-04-01

    Stacked multi-layer films have a range of well-known applications as optical elements. The various types of theory commonly used to describe optical propagation through such structures rarely take account of the quantum nature of light, though phenomena such as Anderson localization can be proven to occur under suitable conditions. In recent and ongoing work based on quantum electrodynamics, it has been shown possible to rigorously reformulate, in photonic terms, the fundamental mechanisms that are involved in reflection and optical transmission through stacked nanolayers. Accounting for sum-over-pathway features in the quantum mechanical description, this theory treats the sequential interactions of photons with material boundaries in terms of individual scattering events. The study entertains an arbitrary number of reflections in systems comprising two or three internally reflective surfaces. Analytical results are secured, without recourse to FTDT (finite-difference time-domain) software or any other finite-element approximations. Quantum interference effects can be readily identified. The new results, which cast the optical characteristics of such structures in terms of simple, constituent-determined properties, are illustrated by model calculations.

  13. Resonant magnetoelectric response of composite cantilevers: Theory of short vs. open circuit operation and layer sequence effects

    Directory of Open Access Journals (Sweden)

    Matthias C. Krantz

    2015-11-01

    Full Text Available The magnetoelectric effect in layered composite cantilevers consisting of strain coupled layers of magnetostrictive (MS, piezoelectric (PE, and substrate materials is investigated for magnetic field excitation at bending resonance. Analytic theories are derived for the transverse magnetoelectric (ME response in short and open circuit operation for three different layer sequences and results presented and discussed for the FeCoBSi-AlN-Si and the FeCoBSi-PZT-Si composite systems. Response optimized PE-MS layer thickness ratios are found to greatly change with operation mode shifting from near equal MS and PE layer thicknesses in the open circuit mode to near vanishing PE layer thicknesses in short circuit operation for all layer sequences. In addition the substrate layer thickness is found to differently affect the open and short circuit ME response producing shifts and reversal between ME response maxima depending on layer sequence. The observed rich ME response behavior for different layer thicknesses, sequences, operating modes, and PE materials can be explained by common neutral plane effects and different elastic compliance effects in short and open circuit operation.

  14. Moisture dependent thermal properties of hydrophilic mineral wool: application of the effective media theory

    Directory of Open Access Journals (Sweden)

    Iñigo Antepara

    2015-09-01

    Full Text Available Thermal properties of mineral wool based materials appear to be of particular importance for their practical applications because the majority of them is used in the form of thermal insulation boards. Every catalogue list of any material producer of mineral wool contains thermal conductivity, sometimes also specific heat capacity, but they give only single characteristic values for dry state of material mostly. Exposure to outside climate or any other environment containing moisture can negatively affect the thermal insulation properties of mineral wool. Nevertheless, the mineral wool materials due to their climatic loading and their environmental exposure contain moisture that can negatively affect their thermal insulation properties. Because the presence of water in mineral wool material is undesirable for the majority of applications, many products are provided with hydrophobic substances. Hydrophilic additives are seldom used in mineral wool products. However, this kind of materials has a good potential for application for instance in interior thermal insulation systems, masonry desalination, green roofs, etc. For these materials, certain moisture content must be estimated and thus their thermal properties will be different than for the dry state. On this account, moisture dependent thermal properties of hydrophilic mineral wool (HMW are studied in a wide range of moisture content using a pulse technique. The experimentally determined thermal conductivity data is analysed using several homogenization formulas based on the effective media theory. In terms of homogenization, a porous material is considered as a mixture of two or three phases. In case of dry state, material consists from solid and gaseous phase. When moistened, liquid phase is also present. Mineral wool consists of the solid phase represented by basalt fibers, the liquid phase by water and the gaseous phase by air. At first, the homogenization techniques are applied for the

  15. On the theory of electric double layer with explicit account of a polarizable co-solvent.

    Science.gov (United States)

    Budkov, Yu A; Kolesnikov, A L; Kiselev, M G

    2016-05-14

    We present a continuation of our theoretical research into the influence of co-solvent polarizability on a differential capacitance of the electric double layer. We formulate a modified Poisson-Boltzmann theory, using the formalism of density functional approach on the level of local density approximation taking into account the electrostatic interactions of ions and co-solvent molecules as well as their excluded volume. We derive the modified Poisson-Boltzmann equation, considering the three-component symmetric lattice gas model as a reference system and minimizing the grand thermodynamic potential with respect to the electrostatic potential. We apply present modified Poisson-Boltzmann equation to the electric double layer theory, showing that accounting for the excluded volume of co-solvent molecules and ions slightly changes the main result of our previous simplified theory. Namely, in the case of small co-solvent polarizability with its increase under the enough small surface potentials of electrode, the differential capacitance undergoes the significant growth. Oppositely, when the surface potential exceeds some threshold value (which is slightly smaller than the saturation potential), the increase in the co-solvent polarizability results in a differential capacitance decrease. However, when the co-solvent polarizability exceeds some threshold value, its increase generates a considerable enhancement of the differential capacitance in a wide range of surface potentials. We demonstrate that two qualitatively different behaviors of the differential capacitance are related to the depletion and adsorption of co-solvent molecules at the charged electrode. We show that an additive of the strongly polarizable co-solvent to an electrolyte solution can shift significantly the saturation potential in two qualitatively different manners. Namely, a small additive of strongly polarizable co-solvent results in a shift of saturation potential to higher surface potentials. On

  16. Thermo-Elastic Triangular Sandwich Element for the Complete Stress Field Based on a Single-Layer Theory

    Science.gov (United States)

    Das, M.; Barut, A.; Madenci, E.; Ambur, D. R.

    2004-01-01

    This study presents a new triangular finite element for modeling thick sandwich panels, subjected to thermo-mechanical loading, based on a {3,2}-order single-layer plate theory. A hybrid energy functional is employed in the derivation of the element because of a C interelement continuity requirement. The single-layer theory is based on five weighted-average field variables arising from the cubic and quadratic representations of the in-plane and transverse displacement fields, respectively. The variations of temperature and distributed loading acting on the top and bottom surfaces are non-uniform. The temperature varies linearly through the thickness.

  17. Significance of vapor phase chemical reactions on CVD rates predicted by chemically frozen and local thermochemical equilibrium boundary layer theories

    Science.gov (United States)

    Gokoglu, Suleyman A.

    1988-01-01

    This paper investigates the role played by vapor-phase chemical reactions on CVD rates by comparing the results of two extreme theories developed to predict CVD mass transport rates in the absence of interfacial kinetic barrier: one based on chemically frozen boundary layer and the other based on local thermochemical equilibrium. Both theories consider laminar convective-diffusion boundary layers at high Reynolds numbers and include thermal (Soret) diffusion and variable property effects. As an example, Na2SO4 deposition was studied. It was found that gas phase reactions have no important role on Na2SO4 deposition rates and on the predictions of the theories. The implications of the predictions of the two theories to other CVD systems are discussed.

  18. "Was it something I said?" "No, it was something you posted!" A study of the spiral of silence theory in social media contexts.

    Science.gov (United States)

    Gearhart, Sherice; Zhang, Weiwu

    2015-04-01

    New media technologies make it necessary for scholars to reassess mass communication theories developed among legacy media. One such theory is the spiral of silence theory originally proposed by Noelle-Neumann in the 1970s. Increasing diversity of media content, selectivity, social networking site (SNS) interactivity, and the potential for anonymity have posed various challenges to its theoretical assumptions. While application of the spiral of silence in SNS contexts has been theorized, its empirical testing is scarce. To fill this void, the Pew 2012 Search, Social Networks, and Politics survey is used to test the theory. Results reveal that encountering agreeable political content predicts speaking out, while encountering disagreeable postings stifles opinion expression, supporting the spiral of silence theory in the SNS environment. However, certain uses of SNSs and psychological factors demonstrate a liberating effect on opinion expression.

  19. Anisotropic diffusion filter based edge enhancement for the segmentation of carotid intima-media layer in ultrasound images using variational level set method without re-initialisation.

    Science.gov (United States)

    Sumathi, K; Anandh, K R; Mahesh, V; Ramakrishnan, S

    2014-01-01

    In this work an attempt has been made to enhance the edges and segment the boundary of intima-media layer of Common Carotid Artery (CCA) using anisotropic diffusion filter and level set method. Ultrasound B mode longitudinal images of normal and abnormal images of common carotid arteries are used in this study. The images are subjected to anisotropic diffusion filter to generate edge map. This edge map is used as a stopping boundary in variational level set method without re-initialisation to segment the intima-media layer. Geometric features are extracted from this layer and analyzed statistically. Results show that anisotropic diffusion filtering is able to extract the edges in both normal and abnormal images. The obtained edge maps are found to have high contrast and sharp edges. The edge based variational level set method is able to segment the intima-media layer precisely from common carotid artery. The extracted geometrical features such as major axis and extent are found to be statistically significant in differentiating normal and abnormal images. Thus this study seems to be clinically useful in diagnosis of cardiovascular disease.

  20. From Transportation to Transformation: On the Use of the Metaphor of Translation within Media and Communication Theory

    Directory of Open Access Journals (Sweden)

    Rainer Guldin

    2012-06-01

    Full Text Available This paper explores some of the common ground between media/communication and translation theory by focusing on the double metaphor of transportation/transformation. The first part of the paper deals with the more general theoretical implications of a possible interchange between communication and translation in view of the notion of spatiality and the paradigmatic change that has occurred in translation theory in the last few years moving from a transportation to a transformation oriented approach to the process of translation. The second part focuses on the work of a series of theorists who have made extensive use of the metaphor of translation to describe inter-mediatic and communicative processes: Marshall McLuhan, Vilém Flusser, Lev Manovich, and Michel Serres. This section shows that despite the use of a transformative definition of the functioning of translation the single authors have neglected to address the question of the actual nature of this transformative process. Finally, therefore, the paper discusses the relevance of the use of the metaphor of translation within communication and media theory in view of a closer definition of its transformative power.

  1. Study of the interaction of the optical radiation with media by means of the group theory: description and applications

    Science.gov (United States)

    Pereda-Cubián, D.; Arce-Diego, J. L.; Fanjul-Vélez, F.; Wang, L. V.

    2006-02-01

    Group theory is a mathematical method, largely used in applications like quantum mechanics and radar theory, which allows establishing a direct relation between the elements of different groups and that can be easily extended to optics. The groups of the special unitary matrices, SU(n), possess a great importance in the field of optics, as they can be related to the light polarization, planar propagation properties and optical devices properties. By means of the Pauli, Gell-Mann and Dirac matrices, respectively for n=2, n=3 and n=4, a corresponding coherence matrix can be defined. In the case of n=2, this coherence matrix describes the behavior of optical radiation at any case, polarized, depolarized or partially polarized light. For n=3, it can be used for the analysis of non-planar waves. Finally, for n=4, the coherence matrix allows the analysis of the polarization properties of the optical devices, from linear and deterministic media to highly scattering or depolarizing media. In this work, the theoretical background of the group theory and its application to optics is described, and some examples of its application are presented, for instance, the description of optical devices by the Quaternions and the application of 4x4 coherence matrix for the characterization of biological tissues by means of the entropy-factor.

  2. Atomistic kinetic Monte Carlo study of atomic layer deposition derived from density functional theory.

    Science.gov (United States)

    Shirazi, Mahdi; Elliott, Simon D

    2014-01-30

    To describe the atomic layer deposition (ALD) reactions of HfO2 from Hf(N(CH3)2)4 and H2O, a three-dimensional on-lattice kinetic Monte-Carlo model is developed. In this model, all atomistic reaction pathways in density functional theory (DFT) are implemented as reaction events on the lattice. This contains all steps, from the early stage of adsorption of each ALD precursor, kinetics of the surface protons, interaction between the remaining precursors (steric effect), influence of remaining fragments on adsorption sites (blocking), densification of each ALD precursor, migration of each ALD precursors, and cooperation between the remaining precursors to adsorb H2O (cooperative effect). The essential chemistry of the ALD reactions depends on the local environment at the surface. The coordination number and a neighbor list are used to implement the dependencies. The validity and necessity of the proposed reaction pathways are statistically established at the mesoscale. The formation of one monolayer of precursor fragments is shown at the end of the metal pulse. Adsorption and dissociation of the H2O precursor onto that layer is described, leading to the delivery of oxygen and protons to the surface during the H2O pulse. Through these processes, the remaining precursor fragments desorb from the surface, leaving the surface with bulk-like and OH-terminated HfO2, ready for the next cycle. The migration of the low coordinated remaining precursor fragments is also proposed. This process introduces a slow reordering motion (crawling) at the mesoscale, leading to the smooth and conformal thin film that is characteristic of ALD.

  3. Depolarizing power and polarization entropy of light scattering media: experiment and theory

    CERN Document Server

    Puentes, G; Aiello, A; Woerdman, J P; Puentes, Graciana; Voigt, Dirk; Aiello, Andrea

    2004-01-01

    We experimentally investigate the depolarizing power and the polarization entropy of a broad class of scattering optical media. By means of polarization tomography, these quantities are derived from an effective Mueller matrix, which is introduced through a formal description of the multi-mode detection scheme we use, as recently proposed by Aiello and Woerdman (arXiv:quant-ph/0407234). This proposal emphasized an intriguing universality in the polarization aspects of classical as well as quantum light scattering; in this contribution we demonstrate experimentally that this universality is obeyed by a surprisingly wide class of depolarizing media. This, in turn, provides the experimentalist with a useful characterization of the polarization properties of any scattering media, as well as a universal criterion for the validity of the measured data.

  4. A Theory-Grounded Measure of Adolescents’ Response to a Media Literacy Intervention

    Science.gov (United States)

    Greene, Kathryn; Yanovitzky, Itzhak; Carpenter, Amanda; Banerjee, Smita C.; Magsamen-Conrad, Kate; Hecht, Michael L.; Elek, Elvira

    2016-01-01

    Media literacy interventions offer promising avenues for the prevention of risky health behaviors among children and adolescents, but current literature remains largely equivocal about their efficacy. The primary objective of this study was to develop and test theoretically-grounded measures of audiences’ degree of engagement with the content of media literacy programs based on the recognition that engagement (and not participation per se) can better explain and predict individual variations in the effects of these programs. We tested the validity and reliability of a measure of engagement with two different samples of 10th grade high school students who participated in a pilot and actual test of a brief media literacy curriculum. Four message evaluation factors (involvement, perceived novelty, critical thinking, personal reflection) emerged and demonstrate acceptable reliability. PMID:28042522

  5. 媒介文化:一种废弃论分析%Media Culture:Analysis of Waste Theory

    Institute of Scientific and Technical Information of China (English)

    潘天波; 刘永宁

    2014-01-01

    在传媒时代,现代媒介已然开启知识的生产、消费与接受的新路径。现代性进程既是书写发展、进步与增益的文明史,也是书写过度、剩余、废弃物以及废弃物处理的荒野史。大规模的媒介文化生产也意味着废弃主义时代的来临,媒介技术缺陷、传播主观色彩、讯息光缆拥塞与他择性传播接受等都是媒介废弃物生产的致命隐患。对现代媒介的废弃论分析,旨在检阅与反思现代传媒及其背后的文化状态,以期诊断媒介文化的废弃假象以及救赎我们对媒介文化的理解力。%In the media era,the modern media have opened the door to a new path of knowledge production, consumption and accept.The process of modernity is not only to write a civilization history of development, progress and gains,but also make out a wilderness history of immoderacy,surplus,waste and waste han-dling.Mass media culture production also means the arrival of the rejecting era.Technical defects,commu-nication subj ective color,message transportation congestion and alternative spread and accept are fatal hid-den trouble of media waste production.Analysis of the modern media waste theory aims to review and re-flect on modern communication and the media culture,in order to diagnose and save our understanding of the media culture.

  6. Rayleigh-Taylor Instability within Sediment Layers Due to Gas Retention: Preliminary Theory and Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gauglitz, Phillip A.; Wells, Beric E.; Buchmiller, William C.; Rassat, Scot D.

    2013-03-21

    In Hanford underground waste storage tanks, a typical waste configuration is settled beds of waste particles beneath liquid layers. The settled beds are typically composed of layers, and these layers can have different physical and chemical properties. One postulated configuration within the settled bed is a less-dense layer beneath a more-dense layer. The different densities can be a result of different gas retention in the layers or different degrees of settling and compaction in the layers. This configuration can experience a Rayleigh-Taylor (RT) instability where the less dense lower layer rises into the upper layer. Previous studies of gas retention and release have not considered potential buoyant motion within a settle bed of solids. The purpose of this report is to provide a review of RT instabilities, discuss predictions of RT behavior for sediment layers, and summarize preliminary experimental observations of RT instabilities in simulant experiments.

  7. Simulation of dynamic processes in three-dimensional layered fractured media with the use of the grid-characteristic numerical method

    Science.gov (United States)

    Golubev, V. I.; Gilyazutdinov, R. I.; Petrov, I. B.; Khokhlov, N. I.; Vasyukov, A. V.

    2017-05-01

    This paper touches upon the computer simulation of the propagation of elastic waves in three-dimensional multilayer fractured media. The dynamic processes are described using the defining system of equations in the partial derivatives of the deformed solid mechanics. The numerical solution of this system is carried out via the grid-characteristic method on curvilinear structural grids. The fractured nature of the medium is accounted for by explicitly selecting the boundaries of individual cracks and setting special boundary conditions in them. Various models of heterogeneous deformed media with a fractured structures are considered: a homogeneous medium, a medium with horizontal boundaries, a medium with inclined boundaries, and a medium curvilinear boundaries. The wave fields detected on the surface are obtained, and their structures are analyzed. It is demonstrated that it is possible to detect the waves scattered from fractured media even in the case of nonparallel (inclined and curvilinear) boundaries of geological layers.

  8. How media campaigns influence children's physical activity: expanding the normative mechanisms of the theory of planned behavior.

    Science.gov (United States)

    Paek, Hye-Jin; Oh, Hyun Jung; Hove, Thomas

    2012-01-01

    This study explicates mechanisms of media campaign effectiveness in the context of children's physical activity. The authors' model expands the theory of planned behavior by integrating injunctive and descriptive norms into its normative mechanism. Analysis of a 3-wave nationally representative evaluation survey among 1,623 tweens indicates that campaign exposure is significantly related, but only indirectly, to both physical activity intention and physical activity behavior. Instead, campaign exposure seems more strongly related to perceived behavioral control and attitudes toward physical activity. By contrast, perceived behavioral control and descriptive norms are strongly related to behavioral intention. The findings suggest that integrating normative mechanisms with the theory of planned behavior can improve efforts to predict and explain a health behavior.

  9. Application of Effective Media Theory for Determination of Thermal Properties of Hollow Bricks as a Function of Moisture Content

    Science.gov (United States)

    Pavlík, Zbyšek; Fiala, Lukáš; Vejmelková, Eva; Černý, Robert

    2013-05-01

    The effective thermal conductivity and effective specific heat capacity of hollow brick blocks are investigated as a function of moisture content. While the effective specific heat capacity as a heat storage parameter is calculated using the linear theory of mixtures, the effective thermal conductivity as a heat transport parameter is analyzed using the effective media theory. At first, the effective thermal conductivity of the dry hollow brick block is calculated using a combination of properties of the brick body and air cavities, and verified using experimental data. Then, the effective thermal conductivity of the brick body is analyzed as a function of moisture content both theoretically and experimentally, and appropriate homogenization formulas are identified. Finally, the effective thermal conductivity of the whole hollow bricks is expressed as a function of moisture content from the dry state to water saturation.

  10. Information content in frequency-dependent, multi-offset GPR data for layered media reconstruction using full-wave inversion

    Science.gov (United States)

    De Coster, Albéric; Phuong Tran, Anh; Lambot, Sébastien

    2014-05-01

    Water lost through leaks can represent high percentages of the total production in water supply systems and constitutes an important issue. Leak detection can be tackled with various techniques such as the ground-penetrating radar (GPR). Based on this technology, various procedures have been elaborated to characterize a leak and its evolution. In this study, we focus on a new full-wave radar modelling approach for near-field conditions, which takes into account the antenna effects as well as the interactions between the antenna(s) and the medium through frequency-dependent global transmission and reflection coefficients. This approach is applied to layered media for which 3-D Green's functions can be calculated. The model allows for a quantitative estimation of the properties of multilayered media by using full-wave inversion. This method, however, proves to be limited to provide users with an on-demand assessment as it is generally computationally demanding and time consuming, depending on the medium configuration as well as the number of unknown parameters to retrieve. In that respect, we propose two leads in order to enhance the parameter retrieval step. The first one consists in analyzing the impact of the reduction of the number of frequencies on the information content. For both numerical and laboratory experiments, this operation has been achieved by investigating the response surface topography of objective functions arising from the comparison between measured and modelled data. The second one involves the numerical implementation of multistatic antenna configurations with constant and variable offsets in the model. These two kinds of analyses are then combined in numerical experiments to observe the conjugated effect of the number of frequencies and the offset configuration. To perform the numerical analyses, synthetic Green's functions were simulated for different multilayered medium configurations. The results show that an antenna offset increase leads

  11. A Theory-Grounded Measure of Adolescents' Response to a Media Literacy Intervention

    Science.gov (United States)

    Greene, Kathryn; Yanovitzky, Itzhak; Carpenter, Amanda; Banerjee, Smita C.; Magsamen-Conrad, Kate; Hecht, Michael L.; Elek, Elvira

    2015-01-01

    Media literacy interventions offer promising avenues for the prevention of risky health behaviors among children and adolescents, but current literature remains largely equivocal about their efficacy. The primary objective of this study was to develop and test theoretically-grounded measures of audiences' degree of engagement with the content of…

  12. A Theory-Grounded Measure of Adolescents' Response to a Media Literacy Intervention

    Science.gov (United States)

    Greene, Kathryn; Yanovitzky, Itzhak; Carpenter, Amanda; Banerjee, Smita C.; Magsamen-Conrad, Kate; Hecht, Michael L.; Elek, Elvira

    2015-01-01

    Media literacy interventions offer promising avenues for the prevention of risky health behaviors among children and adolescents, but current literature remains largely equivocal about their efficacy. The primary objective of this study was to develop and test theoretically-grounded measures of audiences' degree of engagement with the content of…

  13. Homo Ludens 2.0 The Ludic Turn in Media Theory

    NARCIS (Netherlands)

    Raessens, J.F.F.

    2012-01-01

    Including those among you who do not engage in media studies will be familiar with today’s subject – the concept of play. Just open your newspaper and see how this concept imposes itself, both in word and image. Take for example the Dutch cabinet formation in 2010: “Formation rules out of date” de V

  14. Theory vs. "Real Life" Instructional Media Design: A Primer for Those New to the Field.

    Science.gov (United States)

    Saito, Yoshio

    1982-01-01

    Presents a model for instructional media design, adapted from the theoretical model and viewed to work well with reasonable effort and time. An example of the model in use is provided to give evidence of reasonableness. Outlines of both the theoretical and adapted models are provided. (MP)

  15. Turbulence Generation in the Atmospheric Boundary Layer and Limitations of the Monin-Obukhov Similarity Theory

    Science.gov (United States)

    Sun, Jielun; Lenschow, Donald; LeMone, Margaret; Mahrt, Larry

    2015-04-01

    Turbulent fluxes from the Cooperative Atmosphere-Surface Exchange Study in 1999 (CASES-99) field experiment are further analyzed for both day- and nighttime as a follow-on to the investigation of the nighttime turbulence in Sun et al. (2012). The behavior of momentum and heat fluxes is investigated as functions of wind speed and the bulk temperature difference between observation heights and the surface. Vertical variations of momentum and heat flux at a given height z are correlated and are explained in terms of the energy and heat balance in a layer above the ground surface in which the surface heating/cooling and momentum sink need to be included. In addition, the surface also plays an important role in constraining the size of the dominant turbulent eddies, which is directly related to turbulence strength and the length scale of turbulence generation. The turbulence generation is not related to local vertical gradients especially under neutral condition as assumed in Monin-Obukhov similarity theory. Based on the observed relationships between momentum and heat fluxes, a new bulk formula for turbulence parameterization is developed to mainly examine the above-mentioned surface effects on vertical variation of turbulent momentum and heat fluxes. The new understanding of the observed relationships between these turbulent variables and mean variables explains the observed nighttime turbulence regime change observed in Sun et al. (2012) as well as the daytime momentum and heat flux variations with height up to the maximum observation height of 55 m.

  16. Density functional theory predictions of the composition of atomic layer deposition-grown ternary oxides.

    Science.gov (United States)

    Murray, Ciaran; Elliott, Simon D

    2013-05-01

    The surface reactivity of various metal precursors with different alkoxide, amide, and alkyl ligands during the atomic layer deposition (ALD) of ternary oxides was determined using simplified theoretical models. Quantum chemical estimations of the Brønsted reactivity of a metal complex precursor at a hydroxylated surface are made using a gas-phase hydrolysis model. The geometry optimized structures and energies for a large suite of 17 metal precursors (including cations of Mg, Ca, Sr, Sc, Y, La, Ti, Zr, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, and Ga) with five different anionic ligands (conjugate bases of tert-butanol, tetramethyl heptanedione, dimethyl amine, isopropyl amidine, and methane) and the corresponding hydrolyzed complexes are calculated using density functional theory (DFT) methods. The theoretically computed energies are used to determine the energetics of the model reactions. These DFT models of hydrolysis are used to successfully explain the reactivity and resulting stoichiometry in terms of metal cation ratios seen experimentally for a variety of ALD-grown ternary oxide systems.

  17. The Implementation of Cognitive and Constructivism Theory in Media Activities for Sakubun in Seventh Semester at Bina Nusantara University

    Directory of Open Access Journals (Sweden)

    Nalti Novianti

    2012-03-01

    Full Text Available Sakubun is a combination of courses between the language and writing skills. Normally, Japanese language teachers regard this course as hard and difficult. Besides examining the grammar, the teacher has to think really hard to guess the real meaning of the sentences or expressions that the students want to say. Therefore, in order to simplify the process of checking and grading, the writer has conducted a small research toward a Sakubun class. This research was directed to the 7th semester Sakubun class using the Cognitive and the Constructivism theory. Those theories were implemented in four different media as part of the class course material. By differentiating teaching media, learners will not easily become bored during learning process. Teachers could also easily divide the type of materials into two namely: visual and the non-visual, which made learners could easily develop their creativity based on their own personal preferences. The result of the research has shown that there was an improvement of skill in the small group in applying the grammar. This research was conducted during the short semester starting in June until August 2011.

  18. Clarity in Multimedia: The Role of Interactive Media in Teaching Political Science Theories

    Science.gov (United States)

    Cunningham, Alan

    2010-01-01

    The field of political science has encountered a unique obstacle in its development. Contemporary political theory has diverged in opposite paths, becoming more conceptual and abstract as well as focused and concrete. The unfortunate result of this has been a lack of clarity in communicating political theory to a new generation of political…

  19. Grounded Theory in media research and the use of the computer

    NARCIS (Netherlands)

    Hijmans, E.J.S.; Peters, V.A.M.

    2000-01-01

    This article offers, from a perspective of Grounded Theory, a comprehensive summary of general procedures for qualitative analysis and the advantages of the use of the computer. The Grounded Theory Approach is one of the most elaborated methods in the field of interpretive analysis within which anal

  20. Probability theory for 3-layer remote sensing in ideal gas law environment

    National Research Council Canada - National Science Library

    Ben-David, Avishai; Davidson, Charles E

    2013-01-01

    We extend the probability model for 3-layer radiative transfer [Opt. Express 20, 10004 (2012)] to ideal gas conditions where a correlation exists between transmission and temperature of each of the 3 layers...

  1. Linear theory of the Kelvin-Helmholtz instability in the low-latitude boundary layer

    Science.gov (United States)

    Rajaram, R.; Sibeck, D. G.; Mcentire, R. W.

    1991-01-01

    The feasibility is examined of establishing characteristic profiles across the magnetospheric low-latitude boundary layer for the Kelvin-Helmholtz mode so that these profiles can be compared with satellite observations or a latitudinal chain of ground stations. An anisotropic collisionless fluid model is used instead of conventional MHD, and the finite thickness of the boundary layer and the thickness and position of the current layer are taken into account. The instability is found to be enhanced by a decrease in the thickness of the shear layer and of the current layer and by the proximity of the 'current layer' to the outer edge of the shear layer. The velocity threshold for the onset of instability is insensitive to the thickness. Characteristic profiles of the variation of plasma and field parameters across the boundary are obtained, and the importance of parameters specifying the current layer position and thickness is demonstrated.

  2. Spectral polarimetric light-scattering by particulate media: 1. Theory of spectral Vector Radiative Transfer

    Science.gov (United States)

    Ceolato, Romain; Riviere, Nicolas

    2016-07-01

    Spectral polarimetric light-scattering by particulate media has recently attracted growing interests for various applications due to the production of directional broadband light sources. Here the spectral polarimetric light-scattering signatures of particulate media are simulated using a numerical model based on the spectral Vector Radiative Transfer Equation (VRTE). A microphysical analysis is conducted to understand the dependence of the light-scattering signatures upon the microphysical parameters of particles. We reveal that depolarization from multiple scattering results in remarkable spectral and directional features, which are simulated by our model over a wide spectral range from visible to near-infrared. We propose to use these features to improve the inversion of the scattering problem in the fields of remote sensing, astrophysics, material science, or biomedical.

  3. Application of perturbation theory to a P-wave eikonal equation in orthorhombic media

    KAUST Repository

    Stovas, Alexey

    2016-10-12

    The P-wave eikonal equation for orthorhombic (ORT) anisotropic media is a highly nonlinear partial differential equation requiring the solution of a sixth-order polynomial to obtain traveltimes, resulting in complex and time-consuming numerical solutions. To alleviate this complexity, we approximate the solution of this equation by applying a multiparametric perturbation approach. We also investigated the sensitivity of traveltime surfaces inORT mediawith respect to three anelliptic parameters. As a result, a simple and accurate P-wave traveltime approximation valid for ORT media was derived. Two different possible anelliptic parameterizations were compared. One of the parameterizations includes anelliptic parameters defined at zero offset: η1, η2, and ηxy. Another parameterization includes anelliptic parameters defined for all symmetry planes: η1, η2, and η3. The azimuthal behavior of sensitivity coefficients with different parameterizations was used to analyze the crosstalk between anelliptic parameters. © 2016 Society of Exploration Geophysicists.

  4. Basic theories for strain localization analysis of porous media with rate dependent model

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongwu; QIN Jianmin

    2005-01-01

    This paper analyzes the interaction between two kinds of internal length scales when the rate dependent plasticity is introduced to a multiphase material model to study the dynamic strain localization phenomenon of saturated and partially saturated porous media. The stability analysis demonstrates that the enhanced porous media model preserves the well-posedness of the initial value problem for both axial and shear waves because an internal length scale parameter is introduced in the visco-plasticity model. On the other hand, the interaction between the length scale introduced by the rate dependent model and that naturally contained in the governing equations of fully and partially saturated model will take place. A basic method is presented to investigate the internal length scale of the multiphase porous media under the interaction of these two kinds of length scale parameters. Material stability analysis is carried out for a certain permeability from which the results of wave number domain with real wave speed are distinguished. A one dimensional example is given to illustrate the theoretical findings.

  5. Measurement of a multi-layered tear film phantom using optical coherence tomography and statistical decision theory.

    Science.gov (United States)

    Huang, Jinxin; Yuan, Qun; Zhang, Buyun; Xu, Ke; Tankam, Patrice; Clarkson, Eric; Kupinski, Matthew A; Hindman, Holly B; Aquavella, James V; Suleski, Thomas J; Rolland, Jannick P

    2014-12-01

    To extend our understanding of tear film dynamics for the management of dry eye disease, we propose a method to optically sense the tear film and estimate simultaneously the thicknesses of the lipid and aqueous layers. The proposed method, SDT-OCT, combines ultra-high axial resolution optical coherence tomography (OCT) and a robust estimator based on statistical decision theory (SDT) to achieve thickness measurements at the nanometer scale. Unlike conventional Fourier-domain OCT where peak detection of layers occurs in Fourier space, in SDT-OCT thickness is estimated using statistical decision theory directly on the raw spectra acquired with the OCT system. In this paper, we demonstrate in simulation that a customized OCT system tailored to ~1 µm axial point spread function (FWHM) in the corneal tissue, combined with the maximum-likelihood estimator, can estimate thicknesses of the nanometer-scale lipid and micron-scale aqueous layers of the tear film, simultaneously, with nanometer precision. This capability was validated in experiments using a physical phantom that consists of two layers of optical coatings that mimic the lipid and aqueous layers of the tear film.

  6. Generally Covariant Maxwell Theory for Media with a Local Response: Progress since 2000

    CERN Document Server

    Hehl, Friedrich W; Obukhov, Yuri N

    2016-01-01

    In the recent decades, it became more and more popular for engineers, physicists, and mathematicians alike to put the Maxwell equations into a generally covariant form. This is particularly useful for understanding the fundamental structure of electrodynamics (conservation of electric charge and magnetic flux). Moreover, it is ideally suited for applying it to media with local (and mainly linear) response behavior. We try to collect the new knowledge that grew out of this development. We would like to ask the participants of EMTS 2016 to inform us of work that we may have overlooked in our review.

  7. Effects of NAA and BAP, double-layered media, and light distance on in vitro regeneration of Nelumbo nucifera Gaertn. (lotus), an aquatic edible plant.

    Science.gov (United States)

    Mahmad, Noraini; Taha, Rosna Mat; Othman, Rashidi; Saleh, Azani; Hasbullah, Nor Azlina; Elias, Hashimah

    2014-01-01

    In vitro direct regeneration of Nelumbo nucifera Gaertn. was successfully achieved from immature explants (yellow plumule) cultured on a solid MS media supplemented with combinations of 0.5 mg/L BAP and 1.5 mg/L NAA which resulted in 16.00 ± 0.30 number of shoots per explant and exhibited a new characteristic of layered multiple shoots, while normal roots formed on the solid MS basal media. The double-layered media gave the highest number of shoots per explant with a ratio of 2 : 1 (liquid to solid) with a mean number of 16.67 ± 0.23 shoots per explant with the formation of primary and secondary roots from immature explants. In the study involving light distance, the tallest shoot (16.67 ± 0.23 mm) obtained from the immature explants was at a light distance of 200 mm from the source of inflorescent light (1000 lux). The plantlets were successfully acclimatized in clay loam soil after 8 months being maintained under in vitro conditions.

  8. Theory of substrate-directed heat dissipation for single-layer graphene and other two-dimensional crystals

    Science.gov (United States)

    Ong, Zhun-Yong; Cai, Yongqing; Zhang, Gang

    2016-10-01

    We present a theory of the phononic thermal (Kapitza) resistance at the interface between graphene or another single-layer two-dimensional (2D) crystal (e.g., MoS2) and a flat substrate, based on a modified version of the cross-plane heat transfer model by Persson, Volokitin, and Ueba [J. Phys.: Condens. Matter 23, 045009 (2011), 10.1088/0953-8984/23/4/045009]. We show how intrinsic flexural phonon damping is necessary for obtaining a finite Kapitza resistance and also generalize the theory to encased single-layer 2D crystals with a superstrate. We illustrate our model by computing the thermal boundary conductance (TBC) for bare and SiO2-encased single-layer graphene and MoS2 on a SiO2 substrate, using input parameters from first-principles calculation. The estimated room temperatures TBC for bare (encased) graphene and MoS2 on SiO2 are 34.6 (105) and 3.10 (5.07) MWK -1m-2 , respectively. The theory predicts the existence of a phonon frequency crossover point, below which the low-frequency flexural phonons in the bare 2D crystal do not dissipate energy efficiently to the substrate. We explain within the framework of our theory how the encasement of graphene with a top SiO2 layer introduces new low-frequency transmission channels, which significantly reduce the graphene-substrate Kapitza resistance. We emphasize that the distinction between bare and encased 2D crystals must be made in the analysis of cross-plane heat dissipation to the substrate.

  9. Conceptual Tenets of the Theory of Hydration of Heterogeneous Surface with Polar Order of Disperse Ground Layers of Sedimentary Genesis

    Directory of Open Access Journals (Sweden)

    Tamara G. Makeeva

    2012-09-01

    Full Text Available The article, basing on the established regularity defines the basic tenets of the theory of hydration of heterogeneous surface with polar order of disperse ground layers of sedimentary genesis. It offers classification and formula for the associated water density, valid corrections for the associated water density, calculates the water film thickness in disperse ground, develops the reliable physicochemical model of the disperse ground, determines the range of applicability of the existing laboratory and field methods.

  10. GY SAMPLING THEORY AND GEOSTATISTICS: ALTERNATE MODELS OF VARIABILITY IN CONTINUOUS MEDIA

    Science.gov (United States)

    In the sampling theory developed by Pierre Gy, sample variability is modeled as the sum of a set of seven discrete error components. The variogram used in geostatisties provides an alternate model in which several of Gy's error components are combined in a continuous mode...

  11. An Experiential Approach to Teaching Communication Theory: Incorporating Contemporary Media To Clarify Theoretical Concepts.

    Science.gov (United States)

    Lamoureux, Elizabeth R.

    For professors who have been assigned the task of teaching communication theory, carefully chosen examples of films, videos, TV clips, or music can be productively used to support instruction. Both research and experience have shown that the visual and aural channels are excellent forms of amplifying, clarifying, and justifying theoretical…

  12. Microelectrode arrays with overlapped diffusion layers as electroanalytical detectors: theory and basic applications.

    Science.gov (United States)

    Tomčík, Peter

    2013-10-11

    This contribution contains a survey of basic literature dealing with arrays of microelectrodes with overlapping diffusion layers as prospective tools in contemporary electrochemistry. Photolithographic thin layer technology allows the fabrication of sensors of micrometric dimensions separated with a very small gap. This fact allows the diffusion layers of single microelectrodes to overlap as members of the array. Various basic types of microelectrode arrays with interacting diffusion layers are described and their analytical abilities are accented. Theoretical approaches to diffusion layer overlapping and the consequences of close constitution effects such as collection efficiency and redox cycling are discussed. Examples of basis applications in electroanalytical chemistry such as amperometric detectors in HPLC and substitutional stripping voltammetry are also given.

  13. Microelectrode Arrays with Overlapped Diffusion Layers as Electroanalytical Detectors: Theory and Basic Applications

    Directory of Open Access Journals (Sweden)

    Peter Tomčík

    2013-10-01

    Full Text Available This contribution contains a survey of basic literature dealing with arrays of microelectrodes with overlapping diffusion layers as prospective tools in contemporary electrochemistry. Photolithographic thin layer technology allows the fabrication of sensors of micrometric dimensions separated with a very small gap. This fact allows the diffusion layers of single microelectrodes to overlap as members of the array. Various basic types of microelectrode arrays with interacting diffusion layers are described and their analytical abilities are accented. Theoretical approaches to diffusion layer overlapping and the consequences of close constitution effects such as collection efficiency and redox cycling are discussed. Examples of basis applications in electroanalytical chemistry such as amperometric detectors in HPLC and substitutional stripping voltammetry are also given.

  14. FCJ-117 Four Regimes of Entropy: For an Ecology of Genetics and Biomorphic Media Theory

    Directory of Open Access Journals (Sweden)

    Matteo Pasquinelli

    2011-04-01

    Full Text Available This essay approaches the definition of media ecology from two opposite perspectives. On one hand, it tests the homogeneity of the biomimetic continuum, which supposes the mediascape as an extension of the biological realm. On the other, it analyses the biodigital continuum, which takes, for instance, digital code as a universal grammar for genetic code. The problematic relation between biological and technological paradigms and between linguistics and genetics is clarified with reference to Erwin Schrödinger’s concept of negative entropy. Four different regimes of entropic density are then suggested to describe the physical, biological, technological, and cognitive domains. On the basis of this ‘energetic geology’, a new ecology of machines is proposed.

  15. Mass Communication and Mass Media: A Concept of Game Theory Approach

    Directory of Open Access Journals (Sweden)

    H. Tafazzoli

    2015-10-01

    Full Text Available From the historical point of view, the formation and evolution of media in the form that we know today, and according to the age of several thousands of years of human's social life on the soil planet, has changed to reality later. This has happened while the media has evolved in a larger scale with an incredible speed. In those far periods of time the wide propagation and distribution of information to the lots of contacts was not possible because of technical limitations. But people were trying to communicate in a limited form with each other and with their contacts by using other methods. This communication didn't go beyond the human's voice. Through experience they have learnt that if they make a horn with their hands and speak loudly in it from its narrow part, attracts the contact that is further than the usual sound board. But with society's being more complicated, giving information in the shortest time became very important. Various methods of transferring information were formed according to the technology and facilities. In middle ages the bellmen, the singers and the badger storytellers had the duty of information exchange by poems and proverbs, or news and information were written on the animal skin or clay or stone tablets for the distribution and propagation of news. But bringing news and information with primary tools for the contacts were along with some barriers, because their duplication was a hard, time consuming and costly task. Scholars and rulers had found that when the political and governmental information and news reaching time is shorter, consequently its effects on the contacts and their reaction toward the received data would be more.

  16. Helfrich model of membrane bending: from Gibbs theory of liquid interfaces to membranes as thick anisotropic elastic layers.

    Science.gov (United States)

    Campelo, Felix; Arnarez, Clement; Marrink, Siewert J; Kozlov, Michael M

    2014-06-01

    Helfrich model of membrane bending elasticity has been most influential in establishment and development of Soft-Matter Physics of lipid bilayers and biological membranes. Recently, Helfrich theory has been extensively used in Cell Biology to understand the phenomena of shaping, fusion and fission of cellular membranes. The general background of Helfrich theory on the one hand, and the ways of specifying the model parameters on the other, are important for quantitative treatment of particular biologically relevant membrane phenomena. Here we present the origin of Helfrich model within the context of the general Gibbs theory of capillary interfaces, and review the strategies of computing the membrane elastic moduli based on considering a lipid monolayer as a three-dimensional thick layer characterized by trans-monolayer profiles of elastic parameters. We present the results of original computations of these profiles by a state-of-the-art numerical approach.

  17. The Role of Diffusion Media in Nitriding Process on Surface Layers Characteristics of AISI 4140 with and without Hard Chrome Coatings

    Directory of Open Access Journals (Sweden)

    K.A. Widi

    2016-09-01

    Full Text Available The surface layer characteristics of the AISI 4140 tool steel treated by nitriding gas before and after hard chrome plating utilizing pure nitrogen diffusion media (fluidized bed reactor and the without gas (muffle reactor has been studied experimentally. The result shows that nitriding substrate with hard chrome layers has nitrogen atoms concentration almost twice greater than that without hard chrome layers. After being given a hard chrome plating, nitriding on AISI 4140 steel generally has a nitrogen concentration of up to 4 times more than the substrate without hard chrome coating. Almost the entire specimen showed the highest concentration of N atoms in the area below the surface (hardening depth of 200 to 450 µm. N atoms diffusion depth profile has a correlation with hardening depth profile, especially on the specimens layered with hard chromium. The substrate without hard chrome plating tends to have higher surface hardness than the sub-surface. The results show that the effectiveness and efficiency of the gas nitriding diffusion process can be produced without the use of gas in the muffle reactor but the specimens must be hard chromium coated first. This phenomenon can be explained by the role of the passive layer formation that works as a barrier to keeps the spreading of N atoms concentrated in sub-surface areas.

  18. Modeling reactive transport in deformable porous media using the theory of interacting continua.

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Daniel Zack

    2012-01-01

    This report gives an overview of the work done as part of an Early Career LDRD aimed at modeling flow induced damage of materials involving chemical reactions, deformation of the porous matrix, and complex flow phenomena. The numerical formulation is motivated by a mixture theory or theory of interacting continua type approach to coupling the behavior of the fluid and the porous matrix. Results for the proposed method are presented for several engineering problems of interest including carbon dioxide sequestration, hydraulic fracturing, and energetic materials applications. This work is intended to create a general framework for flow induced damage that can be further developed in each of the particular areas addressed below. The results show both convincing proof of the methodologies potential and the need for further validation of the models developed.

  19. Probability theory for 3-layer remote sensing radiative transfer model: univariate case.

    Science.gov (United States)

    Ben-David, Avishai; Davidson, Charles E

    2012-04-23

    A probability model for a 3-layer radiative transfer model (foreground layer, cloud layer, background layer, and an external source at the end of line of sight) has been developed. The 3-layer model is fundamentally important as the primary physical model in passive infrared remote sensing. The probability model is described by the Johnson family of distributions that are used as a fit for theoretically computed moments of the radiative transfer model. From the Johnson family we use the SU distribution that can address a wide range of skewness and kurtosis values (in addition to addressing the first two moments, mean and variance). In the limit, SU can also describe lognormal and normal distributions. With the probability model one can evaluate the potential for detecting a target (vapor cloud layer), the probability of observing thermal contrast, and evaluate performance (receiver operating characteristics curves) in clutter-noise limited scenarios. This is (to our knowledge) the first probability model for the 3-layer remote sensing geometry that treats all parameters as random variables and includes higher-order statistics.

  20. Advances in Unsteady Boundary Layer Transition Research, Part I: Theory and Modeling

    Directory of Open Access Journals (Sweden)

    M. T. Schobeiri

    2003-01-01

    Full Text Available This two-part article presents recent advances in boundary layer research that deal with the unsteady boundary layer transition modeling and its validation. A new unsteady boundary layer transition model was developed based on a universal unsteady intermittency function. It accounts for the effects of periodic unsteady wake flow on the boundary layer transition. To establish the transition model, an inductive approach was implemented; the approach was based on the results of comprehensive experimental and theoretical studies of unsteady wake flow and unsteady boundary layer flow. The experiments were performed on a curved plate at a zero streamwise pressure gradient under a periodic unsteady wake flow, where the frequency of the periodic unsteady flow was varied. To validate the model, systematic experimental investigations were performed on the suction and pressure surfaces of turbine blades integrated into a high-subsonic cascade test facility, which was designed for unsteady boundary layer investigations. The analysis of the experiment's results and comparison with the model's prediction confirm the validity of the model and its ability to predict accurately the unsteady boundary layer transition.

  1. Modeling and simulation of chemically stimulated hydrogel layers using the multifield theory

    Science.gov (United States)

    Sobczyk, Martin; Wallmersperger, Thomas

    2016-04-01

    Polyelectrolyte hydrogels are ionic gels with viscoelastic properties. They are able to reversibly swell and deswell in response to different external stimuli. In the present work stacked layers of hydrogels - also referred to as hydrogel layers - under chemical stimulation are numerically investigated. For this, a set of coupled partial differential equations describing the chemical, the electrical and the mechanical field is solved by using the finite element method. The swelling behavior of the hydrogel layers - obtained by a novel approach for the osmotic pressure - is in excellent agreement with other investigations available in the literature.

  2. Theory of Metallic Work Functions Between Metals and Layers of Exclusion Zone Ordered Water

    CERN Document Server

    Widom, A; Srivastava, Y N

    2016-01-01

    The magnitude of the work function to bring an electron from a metal into the exclusion zone water layer making hydrophilic contact with the metallic interface is theoretically computed. The agreement with recent experimental measurements is satisfactory.

  3. The influence of dielectric layers on the magnetic properties of thin GdFeCo layers for in-plane MAMMOS/MSR media

    Science.gov (United States)

    Hendren, W. R.; Atkinson, R.; Pollard, R. J.; Salter, I. W.; Wright, C. D.; Clegg, W. W.; Jenkins, D. F. L.

    2004-10-01

    The effect of adjacent dielectric layers on sputter deposited GdFeCo, of thickness 10-30 nm, suitable as the readout layer for in-plane magnetic amplifying magneto-optic systems, was investigated by measuring the magnetic hysteresis using magneto-optical Kerr effect at room temperature and above. It was found that the magnetic properties were sensitive to the GdFeCo thickness and the presence of the dielectric layer material. Although alternative materials, ZnS and SiN, were also considered, the paper concentrates on the effects of reactively sputtered AlN, which was the only dielectric that produced the required properties for such thin GdFeCo layers of this type. The effect of reducing GdFeCo thickness was similar to that of reducing Gd content. The percentage of nitrogen used in the sputtering gas during AlN deposition was seen to be crucial to the magnetic properties and to the stability of the films. Films 10 nm thick were particularly affected, the best results requiring less nitrogen than was needed for the thicker films.

  4. Asymptotic theory of double layer and shielding of electric field at the edge of illuminated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Benilov, M. S. [Departamento de Física, CCCEE, Universidade da Madeira, Largo do Município, 9000 Funchal (Portugal); Thomas, D. M. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom)

    2014-04-15

    The method of matched asymptotic expansions is applied to the problem of a collisionless plasma generated by UV illumination localized in a central part of the plasma in the limiting case of small Debye length λ{sub D}. A second-approximation asymptotic solution is found for the double layer positioned at the boundary of the illuminated region and for the un-illuminated plasma for the plane geometry. Numerical calculations for different values of λ{sub D} are reported and found to confirm the asymptotic results. The net integral space charge of the double layer is asymptotically small, although in the plane geometry it is just sufficient to shield the ambipolar electric field existing in the illuminated region and thus to prevent it from penetrating into the un-illuminated region. The double layer has the same mathematical nature as the intermediate transition layer separating an active plasma and a collisionless sheath, and the underlying physics is also the same. In essence, the two layers represent the same physical object: a transonic layer.

  5. Theory and simulation of time-fractional fluid diffusion in porous media

    Science.gov (United States)

    Carcione, José M.; Sanchez-Sesma, Francisco J.; Luzón, Francisco; Perez Gavilán, Juan J.

    2013-08-01

    We simulate a fluid flow in inhomogeneous anisotropic porous media using a time-fractional diffusion equation and the staggered Fourier pseudospectral method to compute the spatial derivatives. A fractional derivative of the order of 0 classical diffusion equation. It implies a time-dependent permeability tensor having a power-law time dependence, which describes memory effects and accounts for anomalous diffusion. We provide a complete analysis of the physics based on plane waves. The concepts of phase, group and energy velocities are analyzed to describe the location of the diffusion front, and the attenuation and quality factors are obtained to quantify the amplitude decay. We also obtain the frequency-domain Green function. The time derivative is computed with the Grünwald-Letnikov summation, which is a finite-difference generalization of the standard finite-difference operator to derivatives of fractional order. The results match the analytical solution obtained from the Green function. An example of the pressure field generated by a fluid injection in a heterogeneous sandstone illustrates the performance of the algorithm for different values of ν. The calculation requires storing the whole pressure field in the computer memory since anomalous diffusion ‘recalls the past’.

  6. Adsorption-Desorption Flow of Condensable Vapors through Mesoporous Media: Network Modeling and Percolation Theory.

    Science.gov (United States)

    Tzevelekos; Kikkinides; Kainourgiakis; Stubos; Kanellopoulos; Kaselouri

    2000-03-01

    Flow of condensable vapors in mesoporous media is investigated theoretically and experimentally during adsorption and desorption processes. A typical permeability curve of a condensable vapor is strongly enhanced in the capillary condensation region. This is because additional capillary pressure gradients are imposed on the capillary-condensed pores, which act as "good" conductors compared to the noncondensed pores, which are considered "poor" conductors. The percolation scaling properties that hold for a system of "good" and "poor" conductors are confirmed for the cases examined. As the ratio of gas flow/capillary-enhanced flow decreases, the rise of permeability with pressure becomes sharper. The network connectivity has a strong impact on the maximum permeability value and on the width of the scaling law regions. The contribution of surface flow does not affect the permeability in the peak region, but results in a shrinkage of the scaling law regions. During desorption, a marked hysteresis in the permeability curves is found and it is attributed only to thermodynamic hysteresis. The maximum permeability values in this case are higher and shifted to lower relative pressures. Copyright 2000 Academic Press.

  7. Coupled mode theory approach to depolarization associated with propagation in turbulent media

    Science.gov (United States)

    Crosignani, B.; di Porto, P.; Clifford, Steven F.

    1988-06-01

    Marcuse's (1974) coupled-mode theory is invoked in the present consideration of the problem of light depolarization in a turbulent atmosphere, in order to allow the evaluation of the depolarization ratio for a plane wave and comparison of its expression with that obtained in the frame of two distinct approaches predicting different behaviors. It is found that both approaches yield the same result when calculated to the same order in both of the relevant smallness parameters, thereby resolving a long-standing controversy.

  8. Statistics of resonances and delay times in random media: beyond random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Kottos, Tsampikos [Department of Physics, Wesleyan University, Middletown, CT 06459-0155 (United States); Max-Planck-Institute for Dynamics and Self-Organization, Bunsenstrasse 10, D-37073 Goettingen (Germany)

    2005-12-09

    We review recent developments in quantum scattering from mesoscopic systems. Various spatial geometries whose closed analogues show diffusive, localized or critical behaviour are considered. These are the features that cannot be described by the universal random matrix theory results. Instead, one has to go beyond this approximation and incorporate them in a non-perturbative way. Here, we pay particular attention to the traces of these non-universal characteristics, in the distribution of the Wigner delay times and resonance widths. The former quantity captures time-dependent aspects of quantum scattering while the latter is associated with the poles of the scattering matrix.

  9. Prediction of adsorption from liquid mixtures in microporous media by the potential theory

    DEFF Research Database (Denmark)

    Monsalvo, Matias Alfonso; Shapiro, Alexander

    2007-01-01

    . With this approach, few parameters are needed to predict adsorption equilibria. The MPTA has been so far used to successfully predict adsorption equilibria of multicomponent gas mixtures. The aim of this work is to extent the MPTA onto adsorption from liquid solutions. We show that such extension is straightforward......Despite its industrial importance, adsorption from the liquid phase has been studied much less extensively than adsorption from the gas phase. In this paper, we study the adsorption of liquid mixtures on the basis of the multicomponent potential theory of adsorption (MPTA). The MPTA is based...

  10. Review on the Research of the Media Literacy Education Theory%媒介素养教育理论研究述评

    Institute of Scientific and Technical Information of China (English)

    韩永青; 林俐

    2016-01-01

    电影等大众传播媒介出现以后,对人类个体和人类社会产生了重大影响,引发西方学界对媒介可能产生负面效应的担忧,西方媒介素养教育理论由此产生,依次经历了四种研究范式,并从20世纪90年代开始逐渐受到中国学界广泛关注与研究。数字技术与网络传播兴起以来,媒介素养教育理论研究陷入困境,借鉴信息素养教育理论研究成果,开展信息素养与媒介素养融合研究已渐成学界共识,将是媒介素养教育理论研究未来发展的重要方向。%The coming of mass media such as movie influenced greatly on the human individuals and human society, and led to the western academic community concern that media may have a negative effect, resulting the beginning of the western media lit-eracy education theory. It went through four kinds of research paradigm and was aroused much attention and studied gradually by the Chinese academic community since the 1990s. The research on media literacy education theory got into trouble when the dig-ital technology and network communication emergenced. It is academic community consensus that the research on the media liter-acy education theory may be using research results of the information literacy education theory and developing information literacy and media literacy fusion research, which will be most important direction in future.

  11. Focusing on media body ideal images triggers food intake among restrained eaters: a test of restraint theory and the elaboration likelihood model.

    Science.gov (United States)

    Boyce, Jessica A; Kuijer, Roeline G

    2014-04-01

    Although research consistently shows that images of thin women in the media (media body ideals) affect women negatively (e.g., increased weight dissatisfaction and food intake), this effect is less clear among restrained eaters. The majority of experiments demonstrate that restrained eaters - identified with the Restraint Scale - consume more food than do other participants after viewing media body ideal images; whereas a minority of experiments suggest that such images trigger restrained eaters' dietary restraint. Weight satisfaction and mood results are just as variable. One reason for these inconsistent results might be that different methods of image exposure (e.g., slideshow vs. film) afford varying levels of attention. Therefore, we manipulated attention levels and measured participants' weight satisfaction and food intake. We based our hypotheses on the elaboration likelihood model and on restraint theory. We hypothesised that advertent (i.e., processing the images via central routes of persuasion) and inadvertent (i.e., processing the images via peripheral routes of persuasion) exposure would trigger differing degrees of weight dissatisfaction and dietary disinhibition among restrained eaters (cf. restraint theory). Participants (N = 174) were assigned to one of four conditions: advertent or inadvertent exposure to media or control images. The dependent variables were measured in a supposedly unrelated study. Although restrained eaters' weight satisfaction was not significantly affected by either media exposure condition, advertent (but not inadvertent) media exposure triggered restrained eaters' eating. These results suggest that teaching restrained eaters how to pay less attention to media body ideal images might be an effective strategy in media-literary interventions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Elastic anisotropy of layered rocks: Ultrasonic measurements of plagioclase-biotite-muscovite (sillimanite) gneiss versus texture-based theoretical predictions (effective media modeling)

    Science.gov (United States)

    Ivankina, T. I.; Zel, I. Yu.; Lokajicek, T.; Kern, H.; Lobanov, K. V.; Zharikov, A. V.

    2017-08-01

    In this paper we present experimental and theoretical studies on a highly anisotropic layered rock sample characterized by alternating layers of biotite and muscovite (retrogressed from sillimanite) and plagioclase and quartz, respectively. We applied two different experimental methods to determine seismic anisotropy at pressures up to 400 MPa: (1) measurement of P- and S-wave phase velocities on a cube in three foliation-related orthogonal directions and (2) measurement of P-wave group velocities on a sphere in 132 directions The combination of the spatial distribution of P-wave velocities on the sphere (converted to phase velocities) with S-wave velocities of three orthogonal structural directions on the cube made it possible to calculate the bulk elastic moduli of the anisotropic rock sample. On the basis of the crystallographic preferred orientations (CPOs) of major minerals obtained by time-of-flight neutron diffraction, effective media modeling was performed using different inclusion methods and averaging procedures. The implementation of a nonlinear approximation of the P-wave velocity-pressure relation was applied to estimate the mineral matrix properties and the orientation distribution of microcracks. Comparison of theoretical calculations of elastic properties of the mineral matrix with those derived from the nonlinear approximation showed discrepancies in elastic moduli and P-wave velocities of about 10%. The observed discrepancies between the effective media modeling and ultrasonic velocity data are a consequence of the inhomogeneous structure of the sample and inability to perform long-wave approximation. Furthermore, small differences between elastic moduli predicted by the different theoretical models, including specific fabric characteristics such as crystallographic texture, grain shape and layering were observed. It is shown that the bulk elastic anisotropy of the sample is basically controlled by the CPO of biotite and muscovite and their volume

  13. MODERN MEDIA EDUCATION MODELS

    Directory of Open Access Journals (Sweden)

    Alexander Fedorov

    2011-03-01

    Full Text Available The author supposed that media education models can be divided into the following groups:- educational-information models (the study of the theory, history, language of media culture, etc., based on the cultural, aesthetic, semiotic, socio-cultural theories of media education;- educational-ethical models (the study of moral, religions, philosophical problems relying on the ethic, religious, ideological, ecological, protectionist theories of media education;- pragmatic models (practical media technology training, based on the uses and gratifications and ‘practical’ theories of media education;- aesthetical models (aimed above all at the development of the artistic taste and enriching the skills of analysis of the best media culture examples. Relies on the aesthetical (art and cultural studies theory; - socio-cultural models (socio-cultural development of a creative personality as to the perception, imagination, visual memory, interpretation analysis, autonomic critical thinking, relying on the cultural studies, semiotic, ethic models of media education.

  14. Measurements and theory for transport layer structure in intense bed-load

    Science.gov (United States)

    Fraccarollo, L.; Capart, H.

    2012-04-01

    We focus on sediment laden flows driven by turbulent open-channel flows where the bed surface is fully mobilized and nonetheless the thickness of the bedload layer is conveniently smaller than the flow depth. This regime presents dynamic and kinematic features which persist in the range of applied Shields stress between about 0.3 and 3. Below the lower limit the moving grains do not develop significant stresses compared to the applied ones; above the upper limit, debris-flow type frictional contacts develop in a non negligible portion of the bedload layer. We report laboratory experiments in which, using high-speed cameras and a laser light sheet, detailed profiles of granular velocity and concentration have been measured. We checked that the transversal bed profile is flat and that the sidewall measurements are representative of the interior domain. The profiles provide new information on transport layer structure and its relation to the applied Shields stress. Contrary to expectations, we find that intense bed-load layers respond to changes in flow conditions by adjusting their granular concentration at the base. Two mechanisms account for the resulting behavior: stresses generated by immersed granular collisions, and equilibration by density stratification. Without parameter adjustment, the deduced constitutive relations capture the responses of velocity, concentration, and layer thickness in the above reported ten-fold increase Shields-stress range. Away from this intermediate range, in both directions, we show how the flow features rapidly change and the theoretical inferences decay.

  15. Electrosynthesized Ni-Al Layered Double Hydroxide-Pt Nanoparticles as an Inorganic Nanocomposite and Potentate Anodic Material for Methanol Electrooxidation in Alkaline Media

    Directory of Open Access Journals (Sweden)

    Biuck Habibi

    2017-04-01

    Full Text Available In this study, Ni-Al layered double hydroxide (LDH-Pt nanoparticles (PtNPs as an inorganic nano-composite was electrosynthesized on the glassy carbon electrode (GCE by a facile and fast two-step electrochemical process. Structure and physicochemical properties of PtNPs/Ni-Al LDH/GCE were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry and electrochemical methods. Then, electrocatalytic and stability characterizations of the PtNPs/Ni-Al LDH/GCE for methanol oxidation in alkaline media were investigated in detail by cyclic voltammetry, chronoamperometry, and chronopotentiometry measurements. PtNPs/Ni-Al LDH/GCE exhibited higher electrocatalytic activity than PtNPs/GCE and Ni-Al LDH/GCE. Also, the resulted chronoam-perograms indicated that the PtNPs/Ni-Al LDH/GCE has a better stability. Copyright © 2017 BCREC GROUP. All rights reserved Received: 30th March 2016; Revised: 29th July 2016; Accepted: 9th September 2016 How to Cite: Habibi, B., Ghaderi, S. (2017. Electro Synthesized Ni-Al Layered Double Hydroxide-Pt Nanoparticles as an Inorganic Nanocomposite and Potentate Anodic Material for Methanol Electro-Oxidation in Alkaline Media. Bulletin of Chemical Reaction Engineering & Catalysis, 12(1: 1-13 (doi:10.9767/bcrec.12.1.460.1-13 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.1.460.1-13

  16. Modern Media Education Models

    Science.gov (United States)

    Fedorov, Alexander

    2011-01-01

    The author supposed that media education models can be divided into the following groups: (1) educational-information models (the study of the theory, history, language of media culture, etc.), based on the cultural, aesthetic, semiotic, socio-cultural theories of media education; (2) educational-ethical models (the study of moral, religions,…

  17. Probability theory for 3-layer remote sensing in ideal gas law environment.

    Science.gov (United States)

    Ben-David, Avishai; Davidson, Charles E

    2013-08-26

    We extend the probability model for 3-layer radiative transfer [Opt. Express 20, 10004 (2012)] to ideal gas conditions where a correlation exists between transmission and temperature of each of the 3 layers. The effect on the probability density function for the at-sensor radiances is surprisingly small, and thus the added complexity of addressing the correlation can be avoided. The small overall effect is due to (a) small perturbations by the correlation on variance population parameters and (b) cancellation of perturbation terms that appear with opposite signs in the model moment expressions.

  18. Structure and Properties of Some Layered U2O5 Phases: A Density Functional Theory Study

    OpenAIRE

    Molinari, Marco; Brincat, Nicholas A.; Allen, Geoffrey C.; Parker, Stephen C.

    2017-01-01

    U2O5 is the boundary composition between the fluorite and the layered structures of the UO2→3 system and the least studied oxide in the group. δ-U2O5 is the only layered structure proposed so far experimentally, although evidence of fluorite-based phases has also been reported. Our DFT work explores possible structures of U2O5 stoichiometry by starting from existing M2O5 structures (where M is an actinide or transition metal) and replacing the M ions with uranium ions. For all structures, we ...

  19. The 30-band k ⋅ p theory of valley splitting in silicon thin layers.

    Science.gov (United States)

    Čukarić, Nemanja A; Partoens, Bart; Tadić, Milan Ž; Arsoski, Vladimir V; Peeters, F M

    2016-05-18

    The valley splitting of the conduction-band states in a thin silicon-on-insulator layer is investigated using the 30-band k ⋅ p theory. The system composed of a few nm thick [Formula: see text] layer embedded within thick SiO2 layers is analyzed. The valley split states are found to cross periodically with increasing quantum well width, and therefore the energy splitting is an oscillatory function of the quantum well width, with period determined by the wave vector K 0 of the conduction band minimum. Because the valley split states are classified by parity, the optical transition between the ground hole state and one of those valley split conduction band states is forbidden. The oscillations in the valley splitting energy decrease with electric field and with smoothing of the composition profile between the well and the barrier by diffusion of oxygen from the SiO2 layers to the Si quantum well. Such a smoothing also leads to a decrease of the interband transition matrix elements. The obtained results are well parametrized by the effective two-valley model, but are found to disagree from previous 30-band calculations. This discrepancy could be traced back to the fact that the basis for the numerical solution of the eigenproblem must be restricted to the first Brillouin zone in order to obtain quantitatively correct results for the valley splitting.

  20. Active vibration control of functionally graded beams with piezoelectric layers based on higher order shear deformation theory

    Science.gov (United States)

    Bendine, K.; Boukhoulda, F. B.; Nouari, M.; Satla, Z.

    2016-12-01

    This paper reports on a study of active vibration control of functionally graded beams with upper and lower surface-bonded piezoelectric layers. The model is based on higher-order shear deformation theory and implemented using the finite element method (FEM). The proprieties of the functionally graded beam (FGB) are graded along the thickness direction. The piezoelectric actuator provides a damping effect on the FGB by means of a velocity feedback control algorithm. A Matlab program has been developed for the FGB model and compared with ANSYS APDL. Using Newmark's method numerical solutions are obtained for the dynamic equations of FGB with piezoelectric layers. Numerical results show the effects of the constituent volume fraction and the influence the feedback control gain on the frequency and dynamic response of FGBs.

  1. Anisotropy of Critical Fields in MgB2: Two-Band Ginzburg-Landau Theory for Layered Superconductors

    Institute of Scientific and Technical Information of China (English)

    I.N. Askerzade; B. Tanatar

    2009-01-01

    The temperature dependence of the anisotropy parameter of upper critical field γHc2 (T)= Hc2(T) / Hc2(T) and London penetration depth γλ(T) = λ(T)/λ (T) are calculated using two-band Ginzburg-Landau theory for layered superconductors. It is shown that, with decreasing temperature the anisotropy parameter γHc2 (T) is increased, while the London penetration depth anisotropy γλ (T) revea/s an opposite behavior. Results of our calculations are in agreement with experimental data for single crystal MgB2 and with other calculations. Results of an analysis of magnetic field Hc1 in a single vortex between superconducting layers are also presented.

  2. Light propagation through weakly scattering media: a study of Monte Carlo vs. diffusion theory with application to neuroimaging

    Science.gov (United States)

    Ancora, Daniele; Zacharopoulos, Athanasios; Ripoll, Jorge; Zacharakis, Giannis

    2015-07-01

    One of the major challenges within Optical Imaging, photon propagation through clear layers embedded between scattering tissues, can be now efficiently modelled in real-time thanks to the Monte Carlo approach based on GPU. Because of its nature, the photon propagation problem can be very easily parallelized and ran on low cost hardware, avoiding the need for expensive Super Computers. A comparison between Diffusion and MC photon propagation theory is presented in this work with application to neuroimaging, investigating low scattering regions in a mouse-like phantom. Regions such as the Cerebral Spinal Fluid, are currently not taken into account in the classical computational models because of the impossibility to accurately simulate light propagation using fast Diffusive Equation approaches, leading to inaccuracies during the reconstruction process. The goal of the study presented here, is to reduce and further improve the computation accuracy of the reconstructed solution in a highly realistic scenario in the case of neuroimaging in preclinical mouse models.

  3. Existence of a natural instability not predicted by theory and connected to a wall deformation in a laminar boundary layer

    Science.gov (United States)

    Gougat, P.; Martin, F.

    1981-01-01

    Natural instability related to negative wall deformation was studied. It was shown that natural instabilities which propagate in a laminar boundary layer of a flat plate are in agreement with stability theory. It is found that if a wall has a deformation, a second frequency does exist, which is not predicted and is twice the first frequency. This second instable frequency only appears if there is a negative velocity gradient. The phenomenon is located very closely to the wall and drops off rapidly when moved away from it.

  4. The Critical Richardson Number and Limits of Applicability of Local Similarity Theory in the Stable Boundary Layer

    CERN Document Server

    Grachev, Andrey A; Fairall, Christopher W; Guest, Peter S; Persson, P Ola G

    2012-01-01

    Measurements of atmospheric turbulence made over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to determine the limits of applicability of Monin-Obukhov similarity theory (in the local scaling formulation) in the stable atmospheric boundary layer. Based on spectral analysis of wind velocity and air temperature fluctuations, it is shown that when both gradient Richardson number, Ri, and flux Richardson number, Rf, exceed a 'critical value' about 0.20-0.25, the inertial subrange associated with the Kolmogorov cascade dies out and vertical turbulent fluxes become small. Some small-scale turbulence survives even in the supercritical regime, but this is non-Kolmogorov turbulence and it decays rapidly with further increasing stability. Similarity theory is based on the turbulent fluxes in the high-frequency part of the spectra that are associated with energy-containing/flux-carrying eddies. Spectral densities in this high-frequency band diminish as the Kolmogorov...

  5. Theory of backward second-harmonic localization in nonlinear left-handed media

    Science.gov (United States)

    Centeno, Emmanuel; Ciracì, Cristian

    2008-12-01

    Recent research on photonic crystals possessing a quadratic nonlinear response has revealed a second-harmonic light localization phenomenon that originates from an all-angle phase matching between counterpropagating Bloch modes at the fundamental and double frequencies [E. Centeno , Phys. Rev. Lett. 98, 263903 (2007)]. In this paper, we develop an electromagnetic theory describing the nature of this parametric light localization, which appears in properly design metamaterials or photonic crystals exhibiting nonlinear left-handed behaviors. We demonstrate that interferences between converging phase-matched and diverging anti-phase-matched waves create a localized second-harmonic wave focused on the pump emitter on the scale of half the wavelength. This light trapping is accompanied by the enhancement of the second-harmonic intensity, which linearly increases with the size of the two-dimensional domain. We finally show that the second-harmonic localization effect previously proposed for GaN photonic crystals can also be obtained with LiNbO3 material.

  6. Maxwell Equations in Media, Group Theory and Polarization of the Light

    CERN Document Server

    Red'kov, V M

    2009-01-01

    In the paper a factorized technique of working with the Lorentz, which closely related to studies of Einstein and Mayer on semi-vectors, and to the systematic construction of the Lorentz group theory on this base given by Fedorov, and also closely related to quaternionic approach, is used. This technique is specified for looking at the problems of light polarization optics in the frames of vector Stokes-Mueller and spinor Jones formalism. Translation to isotropic formalism by Newman and Penrose is described. Some unsolved problems are considered. In particular, because Jones complex formalism has close relation to spinor objects of the Lorentz group, within the field of the light polarization we could have physical realizations on the optical desk of some subtle topological distinctions between orthogonal L_{+}^{\\uparrow} = SO_{0}(3.1) and spinor SL(2.C) groups. These topological differences of the groups find their corollaries in the problem of the so-called spinor structure of physical space-time. Bi-spinor...

  7. Legendre and Laguerre polynomial approach for modeling of wave propagation in layered magneto-electro-elastic media.

    Science.gov (United States)

    Bou Matar, Olivier; Gasmi, Noura; Zhou, Huan; Goueygou, Marc; Talbi, Abdelkrim

    2013-03-01

    A numerical method to compute propagation constants and mode shapes of elastic waves in layered piezoelectric-piezomagnetic composites, potentially deposited on a substrate, is described. The basic feature of the method is the expansion of particle displacement, stress fields, electric and magnetic potentials in each layer on different polynomial bases: Legendre for a layer of finite thickness and Laguerre for the semi-infinite substrate. The exponential convergence rate of the method for propagation of Love waves is numerically verified. The main advantage of the method is to directly determine complex wave numbers for a given frequency via a matricial eigenvalue problem, in a way that no transcendental equation has to be solved. Results are presented and the method is discussed.

  8. Layers of Critical Engagement: Exploring the Intersections of Leadership, Critical Theory, and Learning

    Science.gov (United States)

    Patterson, Shawna M.

    2013-01-01

    In this article, the author provides a model that juxtaposes leadership, critical theory, and learning to address the needs of educators, the organization, and students. This model provides educators with a foundational approach to nurture students' critical consciousness through self-awareness and to actualize transformational change within their…

  9. Layers of Critical Engagement: Exploring the Intersections of Leadership, Critical Theory, and Learning

    Science.gov (United States)

    Patterson, Shawna M.

    2013-01-01

    In this article, the author provides a model that juxtaposes leadership, critical theory, and learning to address the needs of educators, the organization, and students. This model provides educators with a foundational approach to nurture students' critical consciousness through self-awareness and to actualize transformational change within their…

  10. Modeling and simulation of the chemically induced swelling behavior of anionic polyelectrolyte gels by applying the theory of porous media

    Science.gov (United States)

    Leichsenring, Peter; Wallmersperger, Thomas

    2017-03-01

    Ionic hydrogels belong to the class of polyelectrolyte gels, also known as ionic gels. Their ability to swell or shrink under different environmental conditions such as change of pH, ion concentration or temperature make them promising materials for new sensoric or actuatoric devices. Numerical simulations play a crucial role for further developing hydrogel based devices. In the present contribution, a thermodynamically consistent continuum model based on the theory of porous media is derived. The governing field equations are solved on a one-dimensional domain by applying the finite element method. For the time discretization an Euler backward algorithm is implemented. The hydrogel swelling behavior is triggered by a chemical stimulus and is analyzed in space and time. Two mechanical configurations are considered: the hydrogel free swelling behavior and a mechanically clamped configuration, where the hydrogel swelling is hindered, are evaluated in detail. The presented results lead to a precise understanding of the chemo-electro-mechanical behavior and the driving pressure contributions.

  11. On Theory of Dispersive Transport in a Two-Layer Polymer Structure

    Science.gov (United States)

    Sibatov, R. T.; Morozova, E. V.

    2016-09-01

    Dispersive transport of charge carriers in a two-layer polymer structure is modeled on the basis of the integrodifferential equation of hereditary diffusion. The model of multiple trapping in a bilayer is generalized to the case of an arbitrary density of localized states. With the help of an efficient Monte Carlo algorithm, curves of the transient current are calculated and their features are explained within the framework of a stochastic interpretation of the process.

  12. Green's function theory for a magnetic impurity layer in a ferromagnetic Ising film with transverse field

    OpenAIRE

    Leite, R. V.; Morais, B. T. F.; Pereira Jr, J. Milton; Filho, R. N. Costa

    2004-01-01

    A Green's function formalism is used to calculate the spectrum of localized modes of an impurity layer implanted within a ferromagnetic thin film. The equations of motion for the Green's functions are determined in the framework of the Ising model in a transverse field. We show that depending on the thickness, exchange and effective field parameters, there is a ``crossover'' effect between the surface modes and impurity localized modes. For thicker films the results show that the degeneracy o...

  13. Free vibration of three-dimensional anisotropic layered composite nanoplates based on modified couple-stress theory

    Science.gov (United States)

    Guo, Junhong; Chen, Jiangyi; Pan, Ernian

    2017-03-01

    Based on the modified couple-stress theory, three-dimensional analytical solutions of free vibration of a simply supported, multilayered and anisotropic composite nanoplate are derived by solving an eigenvalue system and using the propagator matrix method. By expanding the solutions of the extended displacements in terms of two-dimensional Fourier series, the final governing equations of motion with modified couple-stress effect are reduced to an eigenvalue system of ordinary differential equations. Analytical expressions for the natural frequencies and mode shapes of multilayered anisotropic composite plates with modified couple-stress effect are then derived via the propagator matrix method. Numerical examples are carried out for homogeneous thick-plates and sandwich composite plates to show the effect of the non-local parameter in different layers and stacking sequence on the mode shapes. The present solutions can serve as benchmarks to various thick-plate theories and numerical methods, and could be further useful for designing layered composite structures involving small scale.

  14. Homoclinic behaviors and chaotic motions of double layered viscoelastic nanoplates based on nonlocal theory and extended Melnikov method.

    Science.gov (United States)

    Wang, Yu; Li, Feng-Ming; Wang, Yi-Ze

    2015-06-01

    The nonlinear dynamical equations are established for the double layered viscoelastic nanoplates (DLNP) subjected to in-plane excitation based on the nonlocal theory and von Kármán large deformation theory. The extended high dimensional homoclinic Melnikov method is employed to study the homoclinic phenomena and chaotic motions for the parametrically excited DLNP system. The criteria for the homoclinic transverse intersection for both the asynchronous and synchronous buckling cases are proposed. Lyapunov exponents and phase portraits are obtained to verify the Melnikov-type analysis. The influences of structural parameters on the transverse homoclinic orbits and homoclinic bifurcation sets are discussed for the two buckling cases. Some novel phenomena are observed in the investigation. It should be noticed that the nonlocal effect on the homoclinic behaviors and chaotic motions is quite remarkable. Hence, the small scale effect should be taken into account for homoclinic and chaotic analysis for nanostructures. It is significant that the nonlocal effect on the homoclinic phenomena for the asynchronous buckling case is quite different from that for the synchronous buckling case. Moreover, due to the van der Walls interaction between the layers, the nonlocal effect on the homoclinic behaviors and chaotic motions for high order mode is rather tiny under the asynchronous buckling condition.

  15. Homoclinic behaviors and chaotic motions of double layered viscoelastic nanoplates based on nonlocal theory and extended Melnikov method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu; Wang, Yi-Ze [School of Astronautics, Harbin Institute of Technology, P. O. Box 137, Harbin 150001 (China); Li, Feng-Ming, E-mail: fmli@bjut.edu.cn [School of Astronautics, Harbin Institute of Technology, P. O. Box 137, Harbin 150001 (China); College of Mechanical Engineering, Beijing University of Technology, Beijing 100124 (China)

    2015-06-15

    The nonlinear dynamical equations are established for the double layered viscoelastic nanoplates (DLNP) subjected to in-plane excitation based on the nonlocal theory and von Kármán large deformation theory. The extended high dimensional homoclinic Melnikov method is employed to study the homoclinic phenomena and chaotic motions for the parametrically excited DLNP system. The criteria for the homoclinic transverse intersection for both the asynchronous and synchronous buckling cases are proposed. Lyapunov exponents and phase portraits are obtained to verify the Melnikov-type analysis. The influences of structural parameters on the transverse homoclinic orbits and homoclinic bifurcation sets are discussed for the two buckling cases. Some novel phenomena are observed in the investigation. It should be noticed that the nonlocal effect on the homoclinic behaviors and chaotic motions is quite remarkable. Hence, the small scale effect should be taken into account for homoclinic and chaotic analysis for nanostructures. It is significant that the nonlocal effect on the homoclinic phenomena for the asynchronous buckling case is quite different from that for the synchronous buckling case. Moreover, due to the van der Walls interaction between the layers, the nonlocal effect on the homoclinic behaviors and chaotic motions for high order mode is rather tiny under the asynchronous buckling condition.

  16. Dual-layer write-once media for 1x-4x-speed recording based on Blu-ray Disc format

    Science.gov (United States)

    Uno, Mayumi; Akiyama, Tetsuya; Kitaura, Hideki; Kojima, Rie; Nishiuchi, Kenichi; Yamada, Noboru

    2003-09-01

    We have developed dual-layer write-once media with Te-O-Pd based recording films on Blu-ray (BD) format. Recording capacity was 50GB with dual layers on a disk of 120mm in diameter. Rear and Front layers showed jitters of 5.8% and 7.7% at 1x speed, and 6.0% and 8.0% at 2x speed, respectively, which were good enough to satisfy the BD format. Evaluations were carried out with blue-violet laser of 405nm wavelength, objective lens NA of 0.85. Recording linear velocities were 4.92m/s at BD 1x (36Mbps), and 9.84m/s at BD 2x (72Mbps). Characteristics at 4x speed recording were also examined, and it was revealed that carrier to niose ratio at high recording linear velocity of 19.7m/s, which corresponds to BD 4x (144Mbps), was alomst as same as those of 1x and 2x. Recording mechanism was discussed and proposed a model that Te-O-Pd films were not crystallized directly through solid process, but crystallized through melting.

  17. A fast and accurate method for the simulation of the diffusing temporal light correlation in multi-layered turbid media

    Institute of Scientific and Technical Information of China (English)

    LUO Bin; LI Jun; HE Sai-ling

    2005-01-01

    Monte Carlo simulation of the diffusing temporal light correlation in a multi-layered turbid medium is considered.A straightforward formula is introduced to calculate accurately and efficiently the autocorrelation function at any detector position.The simulation results are in an excellent agreement with an analytical solution of the correlation diffusion equation.

  18. Metal-like Band Structures of Ultrathin Si {111} and {112} Surface Layers Revealed through Density Functional Theory Calculations.

    Science.gov (United States)

    Tan, Chih-Shan; Huang, Michael H

    2017-07-11

    Density functional theory calculations have been performed on Si (100), (110), (111), and (112) planes with tunable number of planes for evaluation of their band structures and density of states profiles. The purpose is to see whether silicon can exhibit facet-dependent properties derived from the presence of a thin surface layer having different band structures. No changes have been observed for single to multiple layers of Si (100) and (110) planes with a consistent band gap between the valence band and the conduction band. However, for 1, 2, 4, and 5 Si (111) and (112) planes, metal-like band structures were obtained with continuous density of states going from the valence band to the conduction band. For 3, 6, and more Si (111) planes, as well as 3 and 6 Si (112) planes, the same band structure as that seen for Si (100) and (110) planes has been obtained. Thus, beyond a layer thickness of five Si (111) planes at ≈1.6 nm, normal semiconductor behavior can be expected. The emergence of metal-like band structures for the Si (111) and (112) planes are related to variation in Si-Si bond length and bond distortion plus 3s and 3p orbital electron contributions in the band structure. This work predicts possession of facet-dependent electrical properties of silicon with consequences in FinFET transistor design. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Two- and three-phase equilibria of polydisperse Yukawa hard-sphere fluids confined in random porous media: high temperature approximation and scaled particle theory.

    Science.gov (United States)

    Hvozd, Taras V; Kalyuzhnyi, Yurij V

    2017-02-15

    We have studied the phase behavior of polydisperse Yukawa hard-sphere fluid confined in random porous media using extension and combination of high temperature approximation and scaled particle theory. The porous media are represented by the matrix of randomly placed hard-sphere obstacles. Due to the confinement, polydispersity effects are substantially enhanced. At an intermediate degree of fluid polydispersity and low density of the matrix, we observe two-phase coexistence with two critical points, and cloud and shadow curves forming closed loops of ellipsoidal shape. With the increase of the matrix density and the constant degree of polydispersity, these two critical points merge and disappear, and at lower temperatures the system fractionates into three coexisting phases. A similar phase behavior was observed in the absence of the porous media caused, however, by the increase of the polydispersity.

  20. Upper limit of applicability of the local similarity theory in the stable atmospheric boundary layer

    Science.gov (United States)

    Grachev, A. A.; Andreas, E. L.; Fairall, C. W.; Guest, P. S.; Persson, P. O. G.

    2012-04-01

    The applicability of the classical Monin-Obukhov similarity theory (1954) has been limited by constant flux assumption, which is valid in a narrow range z/L Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to clarify this issue. Based on spectral analysis of wind velocity and temperature fluctuations, it is shown that when both gradient Richardson number, Ri, and flux Richardson number, Rf, exceed a "critical value" about 0.2-0.25, inertial subrange associated with a Kolmogorov cascade dies out and vertical turbulent fluxes become small. Some small-scale turbulence survives even in the supercritical regime but this is non-Kolmogorov turbulence and it decays rapidly with further increasing stability. The similarity theory is based on the turbulent fluxes in the high frequency part of the spectra associated with energy-containing/flux-carrying eddies. Spectral densities in this high-frequency band collapse along with the Kolmogorov energy cascade. Therefore, applicability of the local Monin-Obukhov similarity theory in the SBL is limited by inequalities Ri < Ri_cr and Rf < Rf_cr (however, Rf_cr = 0.2-0.25 is a primary threshold). Application of this prerequisite shows that both the flux-profile and flux-variances relationships follow to the classical Monin-Obukhov local z-less predictions after the irrelevant cases have been filtered out.

  1. Decoupling of constitutive equations for multi-layered nano-plates embedded in elastic matrix based on non-local elasticity theory using first and higher-order shear deformation theories

    Energy Technology Data Exchange (ETDEWEB)

    Dastjerdi, Shahriar; Aliabadi, Sharifeh; Jabbarzadeh Mehrdad [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-03-15

    The constitutive equations of nano-plates embedded in elastic matrix are derived based on Eringen non-local elasticity theory. Considering the non-local differential constitutive relations of Eringen theory in Cartesian and cylindrical coordinates system based on the first and higher order shear deformation theories and using the Von Karman strain field, the equilibrium differential equations are derived in terms of generalized displacements and rotations. In addition, the obtained governing equations for single layer nano plates are developed for multi-layer nano-plates. Rectangular, annular/circular and sectorial nano-plates are considered. In the most of the investigations in non-local elasticity theory, the classical plate theory (CLPT) is used, however in this paper, the governing equations are derived based on both FSDT and HSDT theories because of obtaining more accurate results.

  2. Theories of multiple equilibria and weather regimes : A critical reexamination. II - Baroclinic two-layer models

    Science.gov (United States)

    Cehelsky, Priscilla; Tung, Ka Kit

    1987-01-01

    Previous results based on low- and intermediate-order truncations of the two-layer model suggest the existence of multiple equilibria and/or multiple weather regimes for the extratropical large-scale flow. The importance of the transient waves in the synoptic scales in organizing the large-scale flow and in the maintenance of weather regimes was emphasized. The result shows that multiple equilibria/weather regimes that are present in lower-order models examined disappear when a sufficient number of modes are kept in the spectral expansion of the solution to the governing partial differential equations. Much of the chaotic behavior of the large-scale flow that is present in intermediate-order models is now found to be spurious. Physical reasons for the drastic modification are offered. A peculiarity in the formulation of most existing two-layer models is noted that also tends to exaggerate the importance of baroclinic processes and increase the degree of unpredictability of the large-scale flow.

  3. Theory of margination and cell-free layer thickness in blood flow

    Science.gov (United States)

    Graham, Michael

    2016-11-01

    A mechanistic model is developed to describe segregation in confined multicomponent suspensions such as blood during Couette or plane Poiseuille flow. We focus attention on the case of a binary suspension with a deformable primary component (e.g. red blood cells) that completely dominates the collision dynamics in the system. The model captures the phenomena of depletion layer formation and margination observed in confined multicomponent suspensions of deformable particles. The depletion layer thickness of the primary component is predicted to follow a master curve relating it in a specific way to confinement ratio and volume fraction. Results from experiments and detailed simulations with different parameters (flexibility, viscosity ratio, confinement) collapse onto this curve with only one adjustable parameter. In a binary suspension, several regimes of segregation arise, depending on the value of a "margination parameter" M. Most importantly, in both Couette and Poiseuille flows there is a critical value of M below which a sharp "drainage transition" occurs: one component is completely depleted from the bulk flow to the vicinity of the walls. Direct simulations also exhibit this transition as the size or flexibility ratio of the components changes.

  4. The Critical Richardson Number and Limits of Applicability of Local Similarity Theory in the Stable Boundary Layer

    Science.gov (United States)

    Grachev, Andrey A.; Andreas, Edgar L.; Fairall, Christopher W.; Guest, Peter S.; Persson, P. Ola G.

    2013-04-01

    Measurements of atmospheric turbulence made over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to determine the limits of applicability of Monin-Obukhov similarity theory (in the local scaling formulation) in the stable atmospheric boundary layer. Based on the spectral analysis of wind velocity and air temperature fluctuations, it is shown that, when both the gradient Richardson number, Ri, and the flux Richardson number, Rf, exceed a `critical value' of about 0.20-0.25, the inertial subrange associated with the Richardson-Kolmogorov cascade dies out and vertical turbulent fluxes become small. Some small-scale turbulence survives even in this supercritical regime, but this is non-Kolmogorov turbulence, and it decays rapidly with further increasing stability. Similarity theory is based on the turbulent fluxes in the high-frequency part of the spectra that are associated with energy-containing/flux-carrying eddies. Spectral densities in this high-frequency band diminish as the Richardson-Kolmogorov energy cascade weakens; therefore, the applicability of local Monin-Obukhov similarity theory in stable conditions is limited by the inequalities Ri < Ri cr and Rf < Rf cr. However, it is found that Rf cr = 0.20-0.25 is a primary threshold for applicability. Applying this prerequisite shows that the data follow classical Monin-Obukhov local z-less predictions after the irrelevant cases (turbulence without the Richardson-Kolmogorov cascade) have been filtered out.

  5. Mixtures of room temperature ionic liquid/ethanol solutions as electrolytic media for cerium oxide thin layer electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Lair, V., E-mail: virginie-lair@chimie-paristech.f [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575-Chimie Paristech (ENSCP)-Paris, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Sirieix-Plenet, J.; Gaillon, L.; Rizzi, C. [UPMC University Paris 06, UMR 7195, Laboratoire de Physicochimie des Electrolytes, Colloides et Sciences Analytiques (PECSA), F-75005 Paris (France); CNRS, UMR 7195, PECSA, F-75005 Paris (France); ESPCI, UMR 7195, PECSA, F-75005 Paris (France); Ringuede, A. [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575-Chimie Paristech (ENSCP)-Paris, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France)

    2010-12-30

    A cerium oxide thin layer was electrodeposited onto stainless steel, using mixed room temperature ionic liquid (the 1-methyl-3-butylimidazolium bis(trifluoromethyl sulfonyl)imide)/ethanol solutions, as electrolytic medium. The hydrophobic ionic liquid content is one of the main parameters in the morphology control influencing the ceria growth rate and crystallinity. Micro-nano structural properties and electrical behaviour are presented, using XRD, SEM/EDS and impedance spectroscopy, as a function of electrodeposition conditions.

  6. Complex-Plane Generalization of Scalar Levin Transforms: A Robust, Rapidly Convergent Method to Compute Potentials and Fields in Multi-Layered Media

    CERN Document Server

    Sainath, Kamalesh; Donderici, Burkay

    2013-01-01

    We propose the complex-plane generalization of a powerful algebraic sequence acceleration algorithm, the Method of Weighted Averages (MWA), to guarantee \\emph{exponential-cum-algebraic} convergence of Fourier and Fourier-Hankel (F-H) integral transforms. This "complex-plane" MWA, effected via a linear-path detour in the complex plane, results in rapid, absolute convergence of field/potential solutions in multi-layered environments \\emph{regardless} of the source-observer geometry and anisotropy/loss of the media present. In this work, we first introduce a new integration path used to evaluate the field contribution arising from the radiation spectra. Subsequently, we (1) exhibit the foundational relations behind the complex-plane extension to a general Levin-type sequence convergence accelerator, (2) specialize this analysis to one member of the Levin transform family (the MWA), (3) address and circumvent restrictions, arising for two-dimensional integrals associated with wave dynamics problems, through minim...

  7. Electrospun cellulose acetate nanofibers as thin layer chromatographic media for eco-friendly screening of steroids adulterated in traditional medicine and nutraceutical products.

    Science.gov (United States)

    Rojanarata, Theerasak; Plianwong, Samarwadee; Su-uta, Kosit; Opanasopit, Praneet; Ngawhirunpat, Tanasait

    2013-10-15

    Nanofibers fabricated from cheap, naturally derived biopolymer, namely cellulose acetate via facile electrospinning technique were successfully applied for the first time to use as separation media for thin layer chromatography (TLC). From the optimization studies, uniform, bead-free nanofibers with good adherence to the backing plates were obtained by electrospinning 17% (w/v) cellulose acetate solution prepared in acetone/N,N-dimethylacetamide (2:1, v-v), using a feed rate of 0.6 mL/h and an electrostatic field strength of 17.5 kV/15 cm for 4h. The nanofibers exhibited reversed phase characteristics, thereby offering the possibility to use simple, polar and more environmental friendly mixtures of water and alcohols as mobile phase. In this work, the application of the fabricated fibers was illustrated by using them combined with the optimal mobile phase e.g. ethanol/water (40:60, v-v) for the screening of steroids adulterated in traditional medicine and nutraceutical products. Due to the satisfactory separation performance, electrospun cellulose acetate nanofibers were shown to be an efficient alternative for TLC media and could be potentially used for the development of green and facile analytical methods. © 2013 Elsevier B.V. All rights reserved.

  8. Singular layers for transmission problems in thin shallow shell theory: Elastic junction case

    Science.gov (United States)

    Merabet, Ismail; Chacha, D. A.; Nicaise, Serge

    2010-05-01

    In this Note we study two-dimensional transmission problems for the linear Koiter's model of an elastic multi-structure composed of two thin shallow shells with the same thickness ɛ≪1, in the elastic junction case. We suppose that the loading is singular, that the elastic coefficients are of different order on each part ( O(ɛ) and O(1) respectively) and that the elastic stiffness coefficient of the hinge is k=O(ɛ). The formal limit problem fails to give a solution satisfying all boundary and transmission conditions; it gives only the outer solution. We derive the inner limit problem which allows us to describe the transmission layer.

  9. Histological comparison of layer media thickness of pulmonary arteroides between Cobb-Vantress and Ross broiler chicken exposed to hypoxia

    OpenAIRE

    Vásquez C., María; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos. Lima, Perú.; Cueva M., Sergio; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima-Perú.; Ayón S., Milder; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos. Lima, Perú.; Lira M., Boris; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima-Perú.; Chavera C., Alfonso; Laboratorio de Histología, Embriología y Patología Veterinaria, Facultad de Medicina Veterinaria de la Universidad Nacional Mayor de San Marcos, Lima; Angulo H., Pedro; Laboratorio de Farmacología y Toxicología Veterinaria, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos. Lima, Perú; Falcón P., Néstor; Facultad de Veterinaria y Zootecnia, Universidad Peruana Cayetano Heredia, Lima

    2012-01-01

    The objective of the present study was to determine the development of the smooth muscle of pulmonary arterioles through the relationship of the smooth muscle layer of pulmonary arteriole/arteriolar diameter (CM/DA). Ninety Cobb-Vantress chicks and 90 Ross chicks were used. Of these, 10 birds were weighed and slaughtered at 1 day of age, and the others were randomly distributed in a group raised at sea level (n=40) and a group raised at 3320 m above the sea level (n=40). Ten birds per group w...

  10. Histological comparison of layer media thickness of pulmonary arteroides between Cobb-Vantress and Ross broiler chicken exposed to hypoxia

    OpenAIRE

    Vásquez C., María; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima-Perú.; Cueva M., Sergio; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima; Ayón S., Milder; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima Perú.; Lira M., Boris; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima; Chavera C., Alfonso; Laboratorio de Histología, Embriología y Patología Veterinaria, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima-Perú.; Angulo H., Pedro; Laboratorio de Farmacología y Toxicología Veterinaria, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos. Lima, Perú; Falcón P., Néstor; Facultad de Veterinaria y Zootecnia, Universidad Peruana Cayetano Heredia, Lima

    2012-01-01

    The objective of the present study was to determine the development of the smooth muscle of pulmonary arterioles through the relationship of the smooth muscle layer of pulmonary arteriole/arteriolar diameter (CM/DA). Ninety Cobb-Vantress chicks and 90 Ross chicks were used. Of these, 10 birds were weighed and slaughtered at 1 day of age, and the others were randomly distributed in a group raised at sea level (n=40) and a group raised at 3320 m above the sea level (n=40). Ten birds per group w...

  11. Palladium on Layered Double Hydroxide: A Heterogeneous System for the Enol Phosphate Carbon-Oxygen Bond Activation in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Jaqueline D. Senra

    2017-01-01

    Full Text Available In this work, a new catalytic approach for the C-O activation of enol phosphates based on a palladium supported on layered double hydroxide was developed. In this case, two different ketene aminal phosphates were used as models to study the synthesis of α-phenyl enecarbamates N-Boc/CBz under the Suzuki-Miyaura conditions. The use of an ortho-bromoaniline as precursor allowed the synthesis of the 2-phenyl indole through an arylation/Heck cyclization. Catalyst reusability enabled the synthesis of the heterocycle in moderate yields for four consecutive runs.

  12. Localization landscape theory of disorder in semiconductors. II. Urbach tails of disordered quantum well layers

    Science.gov (United States)

    Piccardo, Marco; Li, Chi-Kang; Wu, Yuh-Renn; Speck, James S.; Bonef, Bastien; Farrell, Robert M.; Filoche, Marcel; Martinelli, Lucio; Peretti, Jacques; Weisbuch, Claude

    2017-04-01

    Urbach tails in semiconductors are often associated to effects of compositional disorder. The Urbach tail observed in InGaN alloy quantum wells of solar cells and LEDs by biased photocurrent spectroscopy is shown to be characteristic of the ternary alloy disorder. The broadening of the absorption edge observed for quantum wells emitting from violet to green (indium content ranging from 0% to 28%) corresponds to a typical Urbach energy of 20 meV. A three-dimensional absorption model is developed based on a recent theory of disorder-induced localization which provides the effective potential seen by the localized carriers without having to resort to the solution of the Schrödinger equation in a disordered potential. This model incorporating compositional disorder accounts well for the experimental broadening of the Urbach tail of the absorption edge. For energies below the Urbach tail of the InGaN quantum wells, type-II well-to-barrier transitions are observed and modeled. This contribution to the below-band-gap absorption is particularly efficient in near-ultraviolet emitting quantum wells. When reverse biasing the device, the well-to-barrier below-band-gap absorption exhibits a red-shift, while the Urbach tail corresponding to the absorption within the quantum wells is blue-shifted, due to the partial compensation of the internal piezoelectric fields by the external bias. The good agreement between the measured Urbach tail and its modeling by the localization theory demonstrates the applicability of the latter to compositional disorder effects in nitride semiconductors.

  13. Theory of low-power ultra-broadband terahertz sideband generation in bi-layer graphene.

    Science.gov (United States)

    Crosse, J A; Xu, Xiaodong; Sherwin, Mark S; Liu, R B

    2014-09-24

    In a semiconductor illuminated by a strong terahertz (THz) field, optically excited electron-hole pairs can recombine to emit light in a broad frequency comb evenly spaced by twice the THz frequency. Such high-order THz sideband generation is of interest both as an example of extreme nonlinear optics and also as a method for ultrafast electro-optical modulation. So far, this phenomenon has only been observed with large field strengths (~10 kV cm(-1)), an obstacle for technological applications. Here we predict that bi-layer graphene generates high-order sidebands at much weaker THz fields. We find that a THz field of strength 1 kV cm(-1) can produce a high-sideband spectrum of about 30 THz, 100 times broader than in GaAs. The sidebands are generated despite the absence of classical collisions, with the quantum coherence of the electron-hole pairs enabling recombination. These remarkable features lower the barrier to desktop electro-optical modulation at THz frequencies, facilitating ultrafast optical communications.

  14. Optical properties of ion-doped ZnO(Se) layers in the context of band anticrossing theory

    Energy Technology Data Exchange (ETDEWEB)

    Morozova, N. K., E-mail: MorozovaNK@mail.ru [National Research University “Moscow Power Engineering Institute” (Russian Federation); Galstyan, V. G. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Volkov, A. O. [National Research University “Moscow Power Engineering Institute” (Russian Federation); Mashchenko, V. E. [Russian Academy of Sciences, Frumkin Institute of Physical Chemistry and Electrochemistry (Russian Federation)

    2015-09-15

    The study of the optical properties of ZnO(Se) is a continuation of previous studies of ZnS(O), ZnSe(O), and CdS(O) systems in the context of band anticrossing theory. Selenium ions are implanted into high-purity zinc oxide crystals to a concentration of 10{sup 20} cm{sup –3}. The microcathodoluminescence spectra recorded with a scanning electron microscope at a temperature of 100 K provide information from the bulk of the implanted layer. The origin of the orange-red luminescence of ZnO(Se)–Zn layers is clarified. Orangered luminescence is thought to be a result of the formation of a highly mismatched alloy system, in which ZnSe(O) is formed during implantation and radiation annealing. Data suggesting that the green luminescence of pure self-activated ZnO–Zn is the self-activated (SA) emission studied in detail for other II–VI compounds (ZnS(O), ZnSe(O)) and defined by intrinsic defect complexes (A centers) are reported.

  15. Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part 1 - Horizontal TTI layer

    Digital Repository Service at National Institute of Oceanography (India)

    Dewangan, P.; Tsvankin, I.

    rays H20849re- corded at points xH208493H20850 and xH208494H20850H20850 with the same reflection point as the PP reflection xH208491H20850RxH208492H20850.Then the traveltime of the SS-wave is determined from H9270SSH20849xH208493H20850,xH208494H20850H..., the slownesses are computed under the convention that the x3-axis points up and both legs of the PS ray represent upgoing waves H20849i.e., the corresponding group-velocity vectors point toward the earth?s surfaceH20850. Here, we study a horizontal layer in which...

  16. Fundamental measure theory for the electric double layer: implications for blue-energy harvesting and water desalination

    Science.gov (United States)

    Härtel, Andreas; Janssen, Mathijs; Samin, Sela; van Roij, René

    2015-05-01

    Capacitive mixing (CAPMIX) and capacitive deionization (CDI) are promising candidates for harvesting clean, renewable energy and for the energy efficient production of potable water, respectively. Both CAPMIX and CDI involve water-immersed porous carbon (supercapacitors) electrodes at voltages of the order of hundreds of millivolts, such that counter-ionic packing is important for the electric double layer (EDL) which forms near the surfaces of these porous materials. Thus, we propose a density functional theory (DFT) to model the EDL, where the White-Bear mark II fundamental measure theory functional is combined with a mean-field Coulombic and a mean spherical approximation-type correction to describe the interplay between dense packing and electrostatics, in good agreement with molecular dynamics simulations. We discuss the concentration-dependent potential rise due to changes in the chemical potential in capacitors in the context of an over-ideal theoretical description and its impact on energy harvesting and water desalination. Compared to less elaborate mean-field models our DFT calculations reveal a higher work output for blue-energy cycles and a higher energy demand for desalination cycles.

  17. Structure of electric double layers in capacitive systems and to what extent (classical) density functional theory describes it

    Science.gov (United States)

    Härtel, Andreas

    2017-10-01

    Ongoing scientific interest is aimed at the properties and structure of electric double layers (EDLs), which are crucial for capacitive energy storage, water treatment, and energy harvesting technologies like supercapacitors, desalination devices, blue engines, and thermocapacitive heat-to-current converters. A promising tool to describe their physics on a microscopic level is (classical) density functional theory (DFT), which can be applied in order to analyze pair correlations and charge ordering in the primitive model of charged hard spheres. This simple model captures the main properties of ionic liquids and solutions and it predicts many of the phenomena that occur in EDLs. The latter often lead to anomalous response in the differential capacitance of EDLs. This work constructively reviews the powerful theoretical framework of DFT and its recent developments regarding the description of EDLs. It explains to what extent current approaches in DFT describe structural ordering and in-plane transitions in EDLs, which occur when the corresponding electrodes are charged. Further, the review briefly summarizes the history of modeling EDLs, presents applications, and points out limitations and strengths in present theoretical approaches. It concludes that DFT as a sophisticated microscopic theory for ionic systems is expecting a challenging but promising future in both fundamental research and applications in supercapacitive technologies.

  18. Fractures in anisotropic media

    Science.gov (United States)

    Shao, Siyi

    Rocks may be composed of layers and contain fracture sets that cause the hydraulic, mechanical and seismic properties of a rock to be anisotropic. Coexisting fractures and layers in rock give rise to competing mechanisms of anisotropy. For example: (1) at low fracture stiffness, apparent shear-wave anisotropy induced by matrix layering can be masked or enhanced by the presence of a fracture, depending on the fracture orientation with respect to layering, and (2) compressional-wave guided modes generated by parallel fractures can also mask the presence of matrix layerings for particular fracture orientations and fracture specific stiffness. This report focuses on two anisotropic sources that are widely encountered in rock engineering: fractures (mechanical discontinuity) and matrix layering (impedance discontinuity), by investigating: (1) matrix property characterization, i.e., to determine elastic constants in anisotropic solids, (2) interface wave behavior in single-fractured anisotropic media, (3) compressional wave guided modes in parallel-fractured anisotropic media (single fracture orientation) and (4) the elastic response of orthogonal fracture networks. Elastic constants of a medium are required to understand and quantify wave propagation in anisotropic media but are affected by fractures and matrix properties. Experimental observations and analytical analysis demonstrate that behaviors of both fracture interface waves and compressional-wave guided modes for fractures in anisotropic media, are affected by fracture specific stiffness (controlled by external stresses), signal frequency and relative orientation between layerings in the matrix and fractures. A fractured layered medium exhibits: (1) fracture-dominated anisotropy when the fractures are weakly coupled; (2) isotropic behavior when fractures delay waves that are usually fast in a layered medium; and (3) matrix-dominated anisotropy when the fractures are closed and no longer delay the signal. The

  19. Treatmnent Patterns for Pediatric Acute CHUs Media: A Gap in Evidence-Based Theory and Clinical Practice.

    Science.gov (United States)

    Boatright, Courtney; Holcomb, Lygia; Replogle, William

    2015-01-01

    Unnecessary prescribing of antibiotics is costly, leads to serious unintended side effects, and increases the risk of developing antibiotic resistance. Children are at high risk of receiving unnecessary antibiotics because they consume more antibiotics than any other age group, likely due to inaccurate prescribing by health care providers. Treatment of acute otitis media is the most common reason children are prescribed antibiotics. Evidence-based guidelines regarding the appropriate treatment of nonsevere acute otitis media in children have been established. A retrospective, descriptive, chart review project was completed comparing the diagnosis and treatment of acute otitis media in children six months to 12 years of age in clinics and the emergency department of a large academic medical center with the American Academy of Pediatrics' treatment guidelines. Findings of the chart review included 100 patient encounters. Documentation indicated that although none of these children with acute otitis media met the guideline criteria for antibiotics, 92 of the 100 children were prescribed antibiotics.

  20. Physical modelling of elastic anisotropy in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Furre, Anne-Kari

    1997-12-31

    During the last decades, anisotropy has become increasingly interesting in hydrocarbon prospecting. Knowledge of anisotropy in the subsurface can improve reservoir production and data interpretation. This thesis presents experimental studies of three different artificial anisotropic media: layered materials, isotropic matrix with stress-induced fractures, and layered media with controlled crack patterns at an oblique angle relative to layering. Layered media were constructed by varying grain size distributions for different layers, which resulted in acoustic and permeability anisotropy. The thin layer materials could be described by Backus modelling provided the wavelength was much larger than the layer periods. Frequency dependent scattering was observed for waves travelling normal to the layers. Saturated wave velocities were consistent with transverse isotropic Biot theory, but because the permeability anisotropy was small, no flow dependent attenuation anisotropy was observed. When sandstones were cemented under stress and then released, to simulate a vertical core or uplift process, predominantly horizontal cracks developed in the samples. On reloading to the cementing stress level, the velocities were below the initial values, which supports the theories of crack growth. In further triaxial tests on the same material a stress-dependent anisotropy occurred similar to what is often seen in natural samples taken from large depths. 70 refs., 200 figs., 56 tabs.

  1. A second-order, perfectly matched layer formulation to model 3D transient wave propagation in anisotropic elastic media

    CERN Document Server

    Assi, Hisham

    2016-01-01

    Numerical simulation of wave propagation in an infinite medium is made possible by surrounding a finite region by a perfectly matched layer (PML). Using this approach a generalized three-dimensional (3D) formulation is proposed for time-domain modeling of elastic wave propagation in an unbounded lossless anisotropic medium. The formulation is based on a second-order approach that has the advantages of, physical relationship to the underlying equations, and amenability to be implemented in common numerical schemes. Specifically, our formulation uses three second-order equations of the displacement field and nine auxiliary equations, along with the three time histories of the displacement field. The properties of the PML, which are controlled by a complex two-parameter stretch function, are such that it acts as near perfect absorber. Using finite element method (FEM) 3D numerical results are presented for a highly anisotropic medium. An extension of the formulation to the particular case of a Kelvin-Vogit visco...

  2. Mathematical Physics of the Propagation of a Laminar Aerodynamic Boundary Layer, Using the Kinetic Theory of Gases

    Science.gov (United States)

    deGraffenried, Albert L.

    2002-07-01

    The paper presents a derivation showing the propagation mechanisms fundamental to the growth of the laminar aerodynamic boundary layer. The molecular mechanisms basic to such growth are those presented by James Clerk Maxwell in his classic derivation of mu, the viscosity of a gas, based on the Kinetic Theory of Gases. Maxwell's derivation is modified by moving the scene of the analysis from a free-stream location (where he assumes a linear velocity gradient) to a location immediately adjacent an infinite flat plate, using an unknown velocity profile. Gas, initially quiescent above the flat plate, suddenly jumps to velocity U0 at time t=0+. The resultant growth of a boundary-layer velocity profile, vx)(y,t, is solved for in the following manner: a. Phi-up, the stream momentum crossing an element of area, da=dxdz per second per square centimeter, in an upward (+y) direction, is found by integrating through all volume below da, using an unknown velocity profile, vx)(y,t. Similarly, Phi-down, the stream momentum crossing da in a downward (-y) direction is found by integrating through all volume above da. The net stream momentum, Phy(y) equals Phi-up minus Phi-down. The acceleration, dvx/dt of an element of mass dm, equal to rho times dxdydz is set equal to minus the partial of Phi with respect to y, the net momentum-flux gradient, based on Newton's Law. In cylindrical coordinates, azimuth angle gamma is promptly integrated out. Elevation angle theta is integrated-out numerically, using a short BASIC program on a PC. Separation of Variables is assumed, specifically, vx)(y,t may be set equal to f1(y)f2(t), thus producing two separate integro-differential equations which are each set equal to a common constant, -Beta2. LaPlace transforming these two equations into the sy and st domains, applying the Method of Partial Fractions to the sy equation, the FORM of the solution is found, viz., exponential and hyperbolic functions. Boundary conditions are satisfied in order to

  3. Study on the application of shear-wave elastography to thin-layered media and tubular structure: Finite-element analysis and experiment verification

    Science.gov (United States)

    Jang, Jun-keun; Kondo, Kengo; Namita, Takeshi; Yamakawa, Makoto; Shiina, Tsuyoshi

    2016-07-01

    Shear-wave elastography (SWE) enables the noninvasive and quantitative evaluation of the mechanical properties of human soft tissue. Generally, shear-wave velocity (C S) can be estimated using the time-of-flight (TOF) method. Young’s modulus is then calculated directly from the estimated C S. However, because shear waves in thin-layered media propagate as guided waves, C S cannot be accurately estimated using the conventional TOF method. Leaky Lamb dispersion analysis (LLDA) has recently been proposed to overcome this problem. In this study, we performed both experimental and finite-element (FE) analyses to evaluate the advantages of LLDA over TOF. In FE analysis, we investigated why the conventional TOF is ineffective for thin-layered media. In phantom experiments, C S results estimated using the two methods were compared for 1.5 and 2% agar plates and tube phantoms. Furthermore, it was shown that Lamb waves can be applied to tubular structures by extracting lateral waves traveling in the long axis direction of the tube using a two-dimensional window. Also, the effects of the inner radius and stiffness (or shear wavelength) of the tube on the estimation performance of LLDA were experimentally discussed. In phantom experiments, the results indicated good agreement between LLDA (plate phantoms of 2 mm thickness: 5.0 m/s for 1.5% agar and 7.2 m/s for 2% agar; tube phantoms with 2 mm thickness and 2 mm inner radius: 5.1 m/s for 1.5% agar and 7.0 m/s for 2% agar; tube phantoms with 2 mm thickness and 4 mm inner radius: 5.3 m/s for 1.5% agar and 7.3 m/s for 2% agar) and SWE measurements (bulk phantoms: 5.3 m/s ± 0.27 for 1.5% agar and 7.3 m/s ± 0.54 for 2% agar).

  4. Organizational Communication and Media

    DEFF Research Database (Denmark)

    Tække, Jesper

    of Niklas Luhmann (Tække & Paulsen 2008, Tække 2008a) with analysis of how organizations communicate in and about media. Using systems theory and form theory, it puts forward a theoretical framework and a strategy for analysing organisational communication in and about media. The medium aspect is inspired......  The paper reflects an interest in the relation between organizational communication and media. It tries to answer the question, how we can observe the relationship between organizational communication and media. It is a work-in-progress which tries to combine organizational studies inspired...... is a possible framework to draw the two disciplines together in, because it is a theory about the relation between the social and the media it is based on. First the paper sum up the Luhmann inspired theory about organizations, fleshing out how organizations are thought to communicate in and about media and how...

  5. Social Media Reputation

    DEFF Research Database (Denmark)

    Etter, Michael Andreas; Ravasi, Davide; Colleoni, Elanor

    motivational drivers and contextual conditions associated with the formation of narratives in traditional news media and social media influence their content, diffusion, and impact significantly. Our analysis suggests that current theories of media reputation may provide an incomplete representation......Social media enable millions of users to create and disseminate narratives about organizations that increase their public exposure and shape public perceptions. In this paper, we draw on the sociology of news production and research on computer-mediated communication to discuss how different...... of the phenomenon, and highlight theoretically relevant differences and interrelationships between reputational dynamics involving news media and social media....

  6. Surface layer independent model fitting by phase matching: theory and application to HD 49933 and HD 177153 (aka Perky)

    Science.gov (United States)

    Roxburgh, Ian W.

    2015-01-01

    Aims: Our aim is to describe the theory of surface layer independent model fitting by phase matching and to apply this to the stars HD 49933 observed by CoRoT, and HD 177153 (aka Perky) observed by Kepler. Methods: We use theoretical analysis, phase shifts, and model fitting. Results: We define the inner and outer phase shifts of a frequency set of a model star and show that the outer phase shifts are (almost) independent of degree ℓ, and that a function of the inner phase shifts (the phase function) collapses to an ℓ independent function of frequency in the outer layers. We then show how to use this result in a model fitting technique to find a best fit model to an observed frequency set by calculating the inner phase shifts of a model using the observed frequencies and determining the extent to which the phase function collapses to a single function of frequency in the outer layers. This technique does not depend on the radial order n assigned to the observed frequencies. We give two examples applying this technique to the frequency sets of HD 49933 observed by CoRoT and HD 177153 (aka Perky) observed by Kepler, for which measurements of angular diameters and bolometric fluxes are available. For HD 49933 we find a very wide range of models to be consistent with the data (all with convective core overshooting) - and conclude that the data is not precise enough to make any useful restrictions on the structure of this star. For HD 177153 our best fit models have no convective cores, masses in the range 1.15-1.17 M⊙, ages of 4.45-4.70 × 109 yr, Z in the range 0.021-0.024, XH = 0.71-0.72, Y = 0.256 - 0.266 and mixing length parameter α = 1.8. We compare our results to those of previous studies. We contrast the phase matching technique to that using the ratios of small to large separations, showing that it avoids the problem of correlated errors in separation ratio fitting and of assigning radial order n to the modes.

  7. Density functional theory investigation of the electronic structure and thermoelectric properties of layered MoS{sub 2}, MoSe{sub 2} and their mixed-layer compound

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Changhoon; Hong, Jisook [Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Lee, Wang Ro [Faculty of Liberal Education, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Kim, Dae Yeon [Agency for Defense Development (ADD), Chinhae, Kyungnam 645-600 (Korea, Republic of); Shim, Ji Hoon, E-mail: jhshim@postech.ac.kr [Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Divisions of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-03-15

    First principles density functional theory calculations were carried out for the 2H-MoQ{sub 2} (Q=S and Se) and their hypothetical mixed-layer compound. Due to the different electronegativities of S and Se atoms on MoQ{sub 2}, the band gap size could be adjusted in mixed-layer compound MoS{sub 2}/MoSe{sub 2}. Also, the indirect band gap in pure MoQ{sub 2} compounds is changed to the pseudo direct band gap in mixed-layer MoS{sub 2}/MoSe{sub 2} which is similar to the monolayer compound. The layer mixing enhances the thermoelectric properties because of the increased density of states around the Fermi level and the decreased band gap size. Therefore, we suggest that this layer mixing approach should be regarded as a useful way to modulate their electronic structures and to improve their thermoelectric properties. -- Graphical abstract: On the basis of density functional calculations we predict that the mixed-layer compounds 2H-MoS{sub 2}/2H-MoSe{sub 2}, in which two different layers 2H-MoS{sub 2} and 2H-MoSe{sub 2}, have enhanced thermoelectric properties because of the increased density of states around the Fermi level and the decreased band gap size. Highlights: • We explored a way of improving TE properties of 2H-MoQ{sub 2} on DFT methods. • The mixed-layer compounds MoS{sub 2}/MoSe{sub 2} have enhanced thermoelectric properties. • This is caused by modulated electronic structure of mixed layer compound. • Layer mixing approach should be regarded as a useful way to improve TE properties.

  8. Complex-plane generalization of scalar Levin transforms: A robust, rapidly convergent method to compute potentials and fields in multi-layered media

    Science.gov (United States)

    Sainath, Kamalesh; Teixeira, Fernando L.; Donderici, Burkay

    2014-07-01

    We propose the complex-plane generalization of a powerful algebraic sequence acceleration algorithm, the method of weighted averages (MWA), to guarantee exponential-cum-algebraic convergence of Fourier and Fourier-Hankel (F-H) integral transforms. This “complex-plane” MWA, effected via a linear-path detour in the complex plane, results in rapid, absolute convergence of field and potential solutions in multi-layered environments regardless of the source-observer geometry and anisotropy/loss of the media present. In this work, we first introduce a new integration path used to evaluate the field contribution arising from the radiation spectra. Subsequently, we (1) exhibit the foundational relations behind the complex-plane extension to a general Levin-type sequence convergence accelerator, (2) specialize this analysis to one member of the Levin transform family (the MWA), (3) address and circumvent restrictions, arising for two-dimensional integrals associated with wave dynamics problems, through minimal complex-plane detour restrictions and a novel partition of the integration domain, (4) develop and compare two formulations based on standard/real-axis MWA variants, and (5) present validation results and convergence characteristics for one of these two formulations.

  9. Classification of processes for the atomic layer deposition of metals based on mechanistic information from density functional theory calculations

    Science.gov (United States)

    Elliott, S. D.; Dey, G.; Maimaiti, Y.

    2017-02-01

    Reaction cycles for the atomic layer deposition (ALD) of metals are presented, based on the incomplete data that exist about their chemical mechanisms, particularly from density functional theory (DFT) calculations. ALD requires self-limiting adsorption of each precursor, which results from exhaustion of adsorbates from previous ALD pulses and possibly from inactivation of the substrate through adsorption itself. Where the latter reaction does not take place, an "abbreviated cycle" still gives self-limiting ALD, but at a much reduced rate of deposition. Here, for example, ALD growth rates are estimated for abbreviated cycles in H2-based ALD of metals. A wide variety of other processes for the ALD of metals are also outlined and then classified according to which a reagent supplies electrons for reduction of the metal. Detailed results on computing the mechanism of copper ALD by transmetallation are summarized and shown to be consistent with experimental growth rates. Potential routes to the ALD of other transition metals by using complexes of non-innocent diazadienyl ligands as metal sources are also evaluated using DFT.

  10. Classification of processes for the atomic layer deposition of metals based on mechanistic information from density functional theory calculations.

    Science.gov (United States)

    Elliott, S D; Dey, G; Maimaiti, Y

    2017-02-07

    Reaction cycles for the atomic layer deposition (ALD) of metals are presented, based on the incomplete data that exist about their chemical mechanisms, particularly from density functional theory (DFT) calculations. ALD requires self-limiting adsorption of each precursor, which results from exhaustion of adsorbates from previous ALD pulses and possibly from inactivation of the substrate through adsorption itself. Where the latter reaction does not take place, an "abbreviated cycle" still gives self-limiting ALD, but at a much reduced rate of deposition. Here, for example, ALD growth rates are estimated for abbreviated cycles in H2-based ALD of metals. A wide variety of other processes for the ALD of metals are also outlined and then classified according to which a reagent supplies electrons for reduction of the metal. Detailed results on computing the mechanism of copper ALD by transmetallation are summarized and shown to be consistent with experimental growth rates. Potential routes to the ALD of other transition metals by using complexes of non-innocent diazadienyl ligands as metal sources are also evaluated using DFT.

  11. Atomic layer deposition of diisopropylaminosilane on WO3(001) and W(110): a density functional theory study.

    Science.gov (United States)

    Lee, Kyungtae; Lee, Woojin; Lee, Hyo Sug; Shin, Jaikwang; Park, Jieun; Lee, Seongsuk; Choi, Samjong; Kim, Sueryeon; Kim, Jinseong; Shim, Youngseon

    2016-10-26

    The decomposition reactions of the Si precursor, diisopropylaminosilane (DIPAS), on W(110) and hydroxylated WO3(001) surfaces are investigated to elucidate the initial reaction mechanism of the atomic layer deposition (ALD) process using density functional theory (DFT) calculations combined with ab initio molecular dynamics (AIMD) simulations. The decomposition reaction of DIPAS on WO3(001) consists of two steps: Si-N dissociative chemisorption and decomposition of SiH3*. It is found that the Si-N bond cleavage of DIPAS is facile on WO3(001) due to hydrogen bonding between the surface OH group and the N atom of DIPAS. The rate-determining step of DIPAS decomposition on WO3(001) is found to be the Si-H dissociation reaction of the SiH3* reaction intermediate which has an activation barrier of 1.19 eV. On the contrary, sequential Si-H dissociation reactions first occur on W(110) and then the Si-N dissociation reaction of the C5H7NSi* reaction intermediate is found to be the rate-determining step, which has an activation barrier of 1.06 eV. As a result, the final products in the DIPAS decomposition reaction on WO3(001) are Si* and SiH*, whereas Si* atoms remain with carbon impurities on W(110), which imply that the hydroxylated WO3 surface is more efficient for the ALD process.

  12. Confessions of a Media Literacy Scholar-Practitioner: Job Market Advantages, Research Agenda Challenges, and Theory-Driven Production

    Science.gov (United States)

    Boulton, Christopher

    2016-01-01

    This essay explores how higher education's instrumentalist move away from the liberal arts tradition of learning by thinking and towards more vocational "experiential" approaches has implications for media literacy educators' career options, scholarly identities, and teaching strategies. Specifically, I consider my own negotiation of…

  13. Confessions of a Media Literacy Scholar-Practitioner: Job Market Advantages, Research Agenda Challenges, and Theory-Driven Production

    Science.gov (United States)

    Boulton, Christopher

    2016-01-01

    This essay explores how higher education's instrumentalist move away from the liberal arts tradition of learning by thinking and towards more vocational "experiential" approaches has implications for media literacy educators' career options, scholarly identities, and teaching strategies. Specifically, I consider my own negotiation of…

  14. Comprehension of digital media

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju Hwan

    2008-11-15

    This book is divided four parts. The first part describes media and mark on sign and media, what is the sign?, interpretation of sign and semiotics. The second part is for production sign theory and origin of digital revolution such as the problem of origin of digital revolution, homogeneity of producing goods and sign : triple triangle model for production sign theory, triple triangle model for producing goods, triple triangle model of producing sign and triple triangle model of art works. The third parts deals with development of the media and meaning of digital revolution with four changes : invention of letter, appearance of printed media and establishment modernity, appearance electronic media and mess media and appearance of digital media. The last part mentions ontology of world wide web.

  15. Oriented Fiber Filter Media

    Directory of Open Access Journals (Sweden)

    R. Bharadwaj

    2008-06-01

    Full Text Available Coalescing filters are widely used throughout industry and improved performance will reduce droplet emissions and operating costs. Experimental observations show orientation of micro fibers in filter media effect the permeability and the separation efficiency of the filter media. In this work two methods are used to align the fibers to alter the filter structure. The results show that axially aligned fiber media improve quality factor on the order of 20% and cutting media on an angle from a thick layered media can improve performance by about 40%. The results also show the improved performance is not monotonically correlated to the average fiber angle of the medium.

  16. 一非饱和多孔介质层中Love波频散特性%Dispersion characteristics of Love wave in unsaturated layered porous media

    Institute of Scientific and Technical Information of China (English)

    邵长金; 崔为涛; 赵哲; 戴乐根

    2014-01-01

    Using connectivity factor to handle the boundary condition between the two upper layers, the Love wave dispersion equation for three layers in an unsaturated porous media was derived based on the constitutive relations, and then the multi-mode Love wave dispersion curves were calculated numerically. The results indicate that, for the second or higher order Love wave modes, the higher the mode order, the larger the cut off frequency, in contrary to the fundamental mode Love wave which doesn't have cutoff frequency. The maximum velocity of Love waves for all the modes asymptotically reaches the shear wave velocity of the half-space, while the minimum velocity reaches the shear wave velocity in the top layer. The Love wave velocity curves for all the modes are separated by, but are also linked to the shear wave velocity in the second layer. The smoothness of the velocity curves is controlled by the mode number:the higher the mode, the better the smoothness. Analy-ses show that the sensitivity of Love wave phase velocity to different parameters decreases with the order of the following pa-rameters:porosity, saturation, connectivity factor, viscous coefficient and permeability.%为建立更准确的地层反演模型,基于非饱和多孔介质本构关系,用连通率处理上面两层间的边界条件,理论推导出三层非饱和多孔介质中Love 波的频散方程,计算分析多阶模态Love 波频散曲线。结果表明,Love 波第1阶模态没有截止频率,对2阶以上模态,阶数越高截止频率越大。各阶模态的Love波最大速度趋近半空间层的横波速度,而最小速度趋近第1层横波速度。 Love 波速曲线以第2层横波速度为界分为上下两簇,各模态均在第2层横波波速处衔接。模态不同,衔接处曲线的光滑程度不同,模态越高,光滑程度越好。对各参数的敏感性分析表明,孔隙度、饱和度、连通率、黏滞系数和渗透率的变化对Love波相速度影响敏感性依次减小。

  17. Examination of the layer model of the frequency-domain interferometry theory applied in mesosphere-stratosphere-troposphere radars

    Science.gov (United States)

    Chen, J.-S.; Chu, Y.-H.

    2001-01-01

    The thickness and position of an atmospheric layer embedded in the radar volume can be resolved by using the frequency-domain interferometry (FDI) technique in accordance with an analytical expression, in which a single layer with Gaussian shape is assumed. However, the FDI experimental results obtained from the Chung-Li VHF radar show that the layer thickness is usually dependent on the layer position. In view of this, an attempt is made in this paper to interpret the observations. With the help of numerical simulation, we examine three FDI models: (1) a non-Gaussian layer, (2) single layer in company with background scatterers, and (3) multiple layers. The analytical FDI expression derived from the Gaussian-layer model is employed in the numerical study to calculate the layer position and layer thickness on the basis of the coherence and phase estimated from the examined layer model. It shows that the resultant thickness and position of the FDI layer are dependent on each other, which is in agreement with the observed thickness-position relations shown in this paper. Moreover, the numerical results can also provide a reasonable interpretation of the observations reported by earlier scientific workers, such as the discrepancy between the vertical displacement velocity of the layer and the vertical Doppler velocity, the difference in thickness between the FDI-derived layer and in situ observed temperature//humidity sheets, etc. We finally illustrate that the range weighting effect of the radar system plays a crucial role in the FDI-derived thickness-position relations.

  18. A photocatalytic reaction kinetics model based on electrical double layer theory(Ⅰ)--Surface complexation model at TiO2/water interface

    Institute of Scientific and Technical Information of China (English)

    李新军; 李芳柏; 何明兴; 王良焱; 徐悦华; 黄琮

    2002-01-01

    The kinetics of photocatalysis can be us ually described by Langmiur-H inshelwood adsorption expression. The adsorption can be greatly influenced by the surface properties of photocatalyst. Triple layer model (TLM) was chosen to describe the surface adsorption of TiO2 based on electrical double layer (EDL) theory at the TiO2/water interface. And through the potentiometrictit ration the parameters of TLM were determined by the extrapolation method and Fit eql3.1 software. The results show that surface complexation dominates the surfac e charge and the numerical calculation fits the experiment data satisfactorily.

  19. The Study of Electromagnetic Scattering by a Non-perfectly Conductor in Chiral Media by Potential Theory

    Institute of Scientific and Technical Information of China (English)

    GAO TIAN-LING; LIU QIANG; Ma Fu-ming

    2012-01-01

    This paper is concerned with the electromagnetic scattering by a nonperfectly conductor obstacle in chiral environment.A two-dimensional mathematical model is established.The existence and uniqueness of the problem are discussed by potential theory.

  20. Modeling Light Propagation in Luminescent Media

    Science.gov (United States)

    Sahin, Derya

    This study presents physical, computational and analytical modeling approaches for light propagation in luminescent random media. Two different approaches are used, namely (i) a statistical approach: Monte-Carlo simulations for photon transport and (ii) a deterministic approach: radiative transport theory. Both approaches account accurately for the multiple absorption and reemission of light at different wavelengths and for anisotropic luminescence. The deterministic approach is a generalization of radiative transport theory for solving inelastic scattering problems in random media. We use the radiative transport theory to study light propagation in luminescent media. Based on this theory, we also study the optically thick medium. Using perturbation methods, a corrected diffusion approximation with asymptotically accurate boundary conditions and a boundary layer solution are derived. The accuracy and the efficacy of this approach is verified for a plane-parallel slab problem. In particular, we apply these two approaches (MC and radiative transport theory) to model light propagation in semiconductor-based luminescent solar concentrators (LSCs). The computational results for both approaches are compared with each other and found to agree. The results of this dissertation present practical and reliable techniques to use for solving forward/inverse inelastic scattering problems arising in various research areas such as optics, biomedical engineering, nuclear engineering, solar science and material science.

  1. 后现代语境下的传媒研究--论戴维·莫利媒介理论对中国媒介与文化研究的启发%Media Studies In Context of Postmodernity---The Inspiration of David Morley’s Media Theory on China’s Media and Cultural Studies

    Institute of Scientific and Technical Information of China (English)

    宋瑜

    2013-01-01

    David Morley is one of the representatives of the British Cultural Studies .He inherited the aca-demic tradition of the Birmingham School , insisted on interdisciplinary theoretical path , stressed that the media should be studies In the social and physical context and the communication and culture should be examined from a multidisciplinary perspective of sociology , anthropology and semiotics .In the context of postmodern caused by globalized media , Morley tried to to study the dynamic process of globalization and localization of media consumption in the contemporary culture by ethnography , Exploring issues about cross-cultural communi-cation and national identity .Morley's media theory is great inspiration to open up new perspectives and ideas important for China's media and cultural studies , not only help us to understand our current age of media and social context better , but also provide interpretive framework and methodology to understand a serious of media phenomenon and solve problems occurred in media development in the process of China 's modernization .So Morley’s theory is of great significance for both China's media theory studies and media practice .%戴维·莫利是英国文化研究的代表人物之一。他继承了伯明翰学派的学术传统,坚持跨学科的理论路径,强调将媒介研究置于社会和物质的背景下,从社会学、人类学、符号学等多学科视角来审视传播和文化;在全球化媒介构建的后现代语境下,他尝试运用人种志方法研究当代文化中媒介消费的全球化与本土化同时发生的动态过程,探讨有关跨文化传播与民族认同等问题。莫利的媒介理论对中国媒介与文化研究开辟新的视角与思路具有重要的启发,能帮助我们更好地理解当前所处的媒介时代与社会语境,为中国现代化进程中出现的媒介现象与传媒发展等问题提供可借鉴的阐释框架与方法论,对我国媒介理

  2. Density functional theory for the description of spherical non-associating monomers in confined media using the SAFT-VR equation of state and weighted density approximations.

    Science.gov (United States)

    Malheiro, Carine; Mendiboure, Bruno; Plantier, Frédéric; Blas, Felipe J; Miqueu, Christelle

    2014-04-07

    As a first step of an ongoing study of thermodynamic properties and adsorption of complex fluids in confined media, we present a new theoretical description for spherical monomers using the Statistical Associating Fluid Theory for potential of Variable Range (SAFT-VR) and a Non-Local Density Functional Theory (NLDFT) with Weighted Density Approximations (WDA). The well-known Modified Fundamental Measure Theory is used to describe the inhomogeneous hard-sphere contribution as a reference for the monomer and two WDA approaches are developed for the dispersive terms from the high-temperature Barker and Henderson perturbation expansion. The first approach extends the dispersive contributions using the scalar and vector weighted densities introduced in the Fundamental Measure Theory (FMT) and the second one uses a coarse-grained (CG) approach with a unique weighted density. To test the accuracy of this new NLDFT/SAFT-VR coupling, the two versions of the theoretical model are compared with Grand Canonical Monte Carlo (GCMC) molecular simulations using the same molecular model. Only the version with the "CG" approach for the dispersive terms provides results in excellent agreement with GCMC calculations in a wide range of conditions while the "FMT" extension version gives a good representation solely at low pressures. Hence, the "CG" version of the theoretical model is used to reproduce methane adsorption isotherms in a Carbon Molecular Sieve and compared with experimental data after a characterization of the material. The whole results show an excellent agreement between modeling and experiments. Thus, through a complete and consistent comparison both with molecular simulations and with experimental data, the NLDFT/SAFT-VR theory has been validated for the description of monomers.

  3. Density functional theory for the description of spherical non-associating monomers in confined media using the SAFT-VR equation of state and weighted density approximations

    Science.gov (United States)

    Malheiro, Carine; Mendiboure, Bruno; Plantier, Frédéric; Blas, Felipe J.; Miqueu, Christelle

    2014-04-01

    As a first step of an ongoing study of thermodynamic properties and adsorption of complex fluids in confined media, we present a new theoretical description for spherical monomers using the Statistical Associating Fluid Theory for potential of Variable Range (SAFT-VR) and a Non-Local Density Functional Theory (NLDFT) with Weighted Density Approximations (WDA). The well-known Modified Fundamental Measure Theory is used to describe the inhomogeneous hard-sphere contribution as a reference for the monomer and two WDA approaches are developed for the dispersive terms from the high-temperature Barker and Henderson perturbation expansion. The first approach extends the dispersive contributions using the scalar and vector weighted densities introduced in the Fundamental Measure Theory (FMT) and the second one uses a coarse-grained (CG) approach with a unique weighted density. To test the accuracy of this new NLDFT/SAFT-VR coupling, the two versions of the theoretical model are compared with Grand Canonical Monte Carlo (GCMC) molecular simulations using the same molecular model. Only the version with the "CG" approach for the dispersive terms provides results in excellent agreement with GCMC calculations in a wide range of conditions while the "FMT" extension version gives a good representation solely at low pressures. Hence, the "CG" version of the theoretical model is used to reproduce methane adsorption isotherms in a Carbon Molecular Sieve and compared with experimental data after a characterization of the material. The whole results show an excellent agreement between modeling and experiments. Thus, through a complete and consistent comparison both with molecular simulations and with experimental data, the NLDFT/SAFT-VR theory has been validated for the description of monomers.

  4. Free-time and fixed end-point optimal control theory in dissipative media: application to entanglement generation and maintenance.

    Science.gov (United States)

    Mishima, K; Yamashita, K

    2009-07-07

    We develop monotonically convergent free-time and fixed end-point optimal control theory (OCT) in the density-matrix representation to deal with quantum systems showing dissipation. Our theory is more general and flexible for tailoring optimal laser pulses in order to control quantum dynamics with dissipation than the conventional fixed-time and fixed end-point OCT in that the optimal temporal duration of laser pulses can also be optimized exactly. To show the usefulness of our theory, it is applied to the generation and maintenance of the vibrational entanglement of carbon monoxide adsorbed on the copper (100) surface, CO/Cu(100). We demonstrate the numerical results and clarify how to combat vibrational decoherence as much as possible by the tailored shapes of the optimal laser pulses. It is expected that our theory will be general enough to be applied to a variety of dissipative quantum dynamics systems because the decoherence is one of the quantum phenomena sensitive to the temporal duration of the quantum dynamics.

  5. What is Media Innovation?

    OpenAIRE

    2014-01-01

    In order to understand and explain current developments in the media landscape, using the lens of innovation and innovation theory adds value to media research. This chapter gives a theoretical introduction to the concept of innovation. It argues that media innovations may be related to product innovation, process innovation, position innovation, paradigmatic innovation and social innovation, and that innovation may involve different degrees of novelty. The chapter also highlights key influen...

  6. Social Media: Human Life

    Directory of Open Access Journals (Sweden)

    Nick Couldry

    2015-04-01

    Full Text Available This article explores the idea that research into media communications and information has recently undergone a normative turn as more and more writers reflect on the ever deeper embedding of our lives in media, and the possible costs that this entails. Possible ways forward for deepening and addressing this normative turn are explored, based on the particular contribution to media and communications research of social theory.

  7. Multicomponent effective medium-correlated random walk theory for the diffusion of fluid mixtures through porous media.

    Science.gov (United States)

    Bonilla, Mauricio R; Bhatia, Suresh K

    2012-01-10

    Molecular transport in nanoconfined spaces plays a key role in many emerging technologies for gas separation and storage, as well as in nanofluidics. The infiltration of fluid mixtures into the voids of porous frameworks having complex topologies is common place to these technologies, and optimizing their performance entails developing a deeper understanding of how the flow of these mixtures is affected by the morphology of the pore space, particularly its pore size distribution and pore connectivity. Although several techniques have been developed for the estimation of the effective diffusivity characterizing the transport of single fluids through porous materials, this is not the case for fluid mixtures, where the only alternatives rely on a time-consuming solution of the pore network equations or adaptations of the single fluid theories which are useful for a limited type of systems. In this paper, a hybrid multicomponent effective medium-correlated random walk theory for the calculation of the effective transport coefficients matrix of fluid mixtures diffusing through porous materials is developed. The theory is suitable for those systems in which component fluxes at the single pore level can be related to the potential gradients of the different species through linear flux laws and corresponds to a generalization of the classical single fluid effective medium theory for the analysis of random resistor networks. Comparison with simulation of the diffusion of binary CO(2)/H(2)S and ternary CO(2)/H(2)S/C(3)H(8) gas mixtures in membranes modeled as large networks of randomly oriented pores with both continuous and discrete pore size distributions demonstrates the power of the theory, which was tested using the well-known generalized Maxwell-Stefan model for surface diffusion at the single pore level.

  8. Sensitivity kernels for coda-wave interferometry and scattering tomography: theory and numerical evaluation in two-dimensional anisotropically scattering media

    Science.gov (United States)

    Margerin, Ludovic; Planès, Thomas; Mayor, Jessie; Calvet, Marie

    2016-01-01

    Coda-wave interferometry is a technique which exploits tiny waveform changes in the coda to detect temporal variations of seismic properties in evolving media. Observed waveform changes are of two kinds: traveltime perturbations and distortion of seismograms. In the last 10 yr, various theories have been published to relate either background velocity changes to traveltime perturbations, or changes in the scattering properties of the medium to waveform decorrelation. These theories have been limited by assumptions pertaining to the scattering process itself-in particular isotropic scattering, or to the propagation regime-single-scattering and/or diffusion. In this manuscript, we unify and extend previous results from the literature using a radiative transfer approach. This theory allows us to incorporate the effect of anisotropic scattering and to cover a broad range of propagation regimes, including the contribution of coherent, singly scattered and multiply scattered waves. Using basic physical reasoning, we show that two different sensitivity kernels are required to describe traveltime perturbations and waveform decorrelation, respectively, a distinction which has not been well appreciated so far. Previous results from the literature are recovered as limiting cases of our general approach. To evaluate numerically the sensitivity functions, we introduce an improved version of a spectral technique known as the method of `rotated coordinate frames', which allows global evaluation of the Green's function of the radiative transfer equation in a finite domain. The method is validated through direct pointwise comparison with Green's functions obtained by the Monte Carlo method. To illustrate the theory, we consider a series of scattering media displaying increasing levels of scattering anisotropy and discuss the impact on the traveltime and decorrelation kernels. We also consider the related problem of imaging variations of scattering properties based on intensity

  9. Theory and numeric modelling of non-isothermal multiphase processes in NAPL-contaminated porous media; Theorie und numerische Modellierung nichtisothermer Mehrphasenprozesse in NAPL-kontaminierten poroesen Medien

    Energy Technology Data Exchange (ETDEWEB)

    Class, H.

    2000-07-01

    The author investigates the numeric simulation of physical processes in porous media. The development of the model and its components is described, and the model is validated by laboratory experiments. Differences from the discretization methods BOX and CVFE are discussed as well as the applicability of the multigrid method described for multicomponent approaches. [German] Bei der thermischen Sanierung NAPL-kontaminierter Standorte, z.B. durch Injektion von Wasserdampf und/oder Heissluft, treten nichtisotherme Mehrphasenprozesse auf, die in einem Modell durch eine Betrachtung der Stroemungs- und Transportprozesse als Mehrkomponentensystem beschrieben werden koennen. Dabei ist der Austausch thermischer Energie zwischen den Phasen untereinander und auch dem poroesen Medium selbst, wie auch der Uebergang von Massekomponenten zwischen den Phasen zu beruecksichtigen. Die vorliegende Arbeit behandelt die numerische Simulation derartiger physikalischer Vorgaenge in poroesen Medien. Ausgehend von der Problemstellung wird die Entwicklung eines konzeptionellen Modells (Kap. 2) sowie die Umsetzung der daraus resultierenden mathematischen Gleichungen und dazu erforderlichen Diskretisierungs- und Loesungsmethoden in numerische Algorithmen dargestellt (Kap. 3). Anschliessend wird in Kap. 4 die Faehigkeit des erstelten numerischen Modells ueberprueft, Problemstellungen in natuerlichen Systemen zu simulieren (Vergleich mit Laborexperimenten); ausserdem werden Unterschiede der Diskretisierungsverfahren BOX und CVFE sowie die Anwendbarkeit des in dieser Arbeit fuer Mehrkomponentenformulierungen erweiterten Mehrgitterverfahrens diskutiert. (orig.)

  10. 基于系统产权理论的我国传媒产权制度变革研究%Research on Institutional Reform of China's Media Property-Right Based on System Property-Right Theory

    Institute of Scientific and Technical Information of China (English)

    习艳群

    2013-01-01

    当前,传媒产权制度的改革是我国传媒业体制创新的关键突破口。本文以系统经济学及其产权理论为主要理论工具,以系统化的视角全面地剖析了当前我国传媒产权制度的现状及存在的问题,并提出了我国传媒产权制度变革的思路:即构建多层次的传媒产权结构、促进不同层次传媒产权之间的资源位流动,以及发挥传媒主体自组织制度变迁和政府层级型制度变迁的共同作用,推进我国传媒产权制度变革的进程。%At present,institutional reform of media property-right is the key breakthrough point of institu-tional innovation of China's media industry. With system economics and its property right theory as the main theory tool,this thesis conducts comprehensive,objective and vivid analysis of the current condition and problems for China's media property right institution from a systematic perspective,and puts forward the ideas for institutional reform of media property right:1 . Establish multi -level media property right structure;2 . Promote flow of resource -niche between media property right at different levels to realize maximum efficiency of media resource allocation;3 . Give into play common roles of evolution of self-or-ganizing institutions of media subjects and evolution of hierarchical institution of the government so as to promote the process of institutional reform of China's media property right.

  11. Antennas in inhomogeneous media

    CERN Document Server

    Galejs, Janis; Fock, V A; Wait, J R

    2013-01-01

    Antennas in Inhomogeneous Media details the methods of analyzing antennas in such inhomogeneous media. The title covers the complex geometrical configurations along with its variational formulations. The coverage of the text includes various conditions the antennas are subjected to, such as antennas in the interface between two media; antennas in compressible isotropic plasma; and linear antennas in a magnetoionic medium. The selection also covers insulated loops in lossy media; slot antennas with a stratified dielectric or isotropic plasma layers; and cavity-backed slot antennas. The book wil

  12. Initial steps in extending crisis communication theory towards social media crisis dialogue: revisiting situational crisis communication framework

    OpenAIRE

    2013-01-01

    Research Summary The main focus of this research is on the study of stakeholders' naturally occurring reactions to corporate crisis and crisis communication. The literature review aimed to combine situational crisis communication framework (SCCT) with the strategic public relations management theory to establish an idea of strategic two-way crisis communication. The case study evidence is drawn from the Toyota USA Facebook site in relation to the Toyota recall crisis in 2009-2011 and studi...

  13. Establishment of the Coulomb law in the layer phase of a pure U(1) lattice gauge theory

    CERN Document Server

    Farakos, K

    2008-01-01

    In this article we examine the Layer phase of the five dimensional, anisotropic, Abelian gauge model. Our results are to be compared with the ones of the 4D U(1) gauge model in an attempt to verify that four dimensional physics governs the four dimensional layers. The main results are: i) From the analysis of Wilson loops we verified the $\\frac{1}{R}$ behavior, in the layered phase, for the potential between heavy charges. The renormalized fine structure constant in the layer phase is found to be equal to that of 4D Coulomb phase,$\\alpha_{layer}$=$\\alpha_{4D}$. ii) Based on the helicity modulus analysis we show that the layers are in the Coulomb phase while the transverse bulk space is in the confining phase. We also calculated the renormalized coupling $\\beta_{R}$ and found results compatible with those obtained from the Coulomb potential. Finally we calculated the potential in the 5D Coulomb phase and found $\\frac{1}{R^{2}}$ behavior for the static $q \\bar{q}$ potential. From the study of the helicity modul...

  14. Electromagnetic fields in stratified media

    CERN Document Server

    Li, Kai

    2009-01-01

    Dealing with an important branch of electromagnetic theory with many useful applications in subsurface communication, radar, and geophysical prospecting and diagnostics, this book introduces electromagnetic theory and wave propagation in complex media.

  15. New Media, Legacy Media and Misperceptions Regarding Sourcing

    Directory of Open Access Journals (Sweden)

    Stan Diel

    2017-07-01

    Full Text Available Resource dependence theory and related theories of management suggest online-only news media may displace legacy news media, but until that happens the two systems are likely to be dependent on the same resource: news. This quantitative content analysis finds that the systems exist as parallel but distinctly separate entities. Websites associated with legacy news media such as newspapers publish mostly hard news or news analysis in the form of original work. New, online-only news media publish mostly unoriginal features, but the origins of much of the content published by onlineonly media are unclear.

  16. 新媒体环境下“议程设置”理论的转变与发展%The Transformation and Development of "Agenda Setting"Theory under the New Media Environment

    Institute of Scientific and Technical Information of China (English)

    熊玮

    2016-01-01

    以网络、手机为代表的新媒体正深刻影响着大众传播领域,它不仅使传播主体、传播内容、传播方式发生改变,更多的是给经典传播理论带来了危机与挑战。鉴于此,本文以“议程设置”理论为支点,探讨新媒体环境下“议程设置”理论发生的变化,提出该理论只有在传统媒体和新媒体间互动融合的运作才能更好地促进大众传媒业健康持续发展。%The new media represented by the Internet and mobile phones is a profound impact on the mass media.It not only makes the main body of communication,communication content,communication way to change,but also gives the classical theory of communication,which has brought the crisis and challenges.In view of this,this article takes the "agenda setting"theory as the fulcrum,discusses the change of the "agenda setting"theory under the new media environment.It puts forward that the theory can better promote the healthy and sustainable development of the mass media industry only in the traditional media and new media.

  17. Semi-empiric theory of electron-hole pair confined in thin GaAs/Ga(Al)As layer

    Science.gov (United States)

    Garcia, L. F.; Marin, J. H.; Mikhailov, I. D.

    2017-09-01

    We propose a simple theoretical method for analyzing spectral properties of excitons confined in thin semiconductor layers with different morphologies. By using model with a smooth energy misalignment between the energy band edges potential in junctions of a thin layer GaAs/Ga(Al)As heterostructure, we find interpolation formulae, which relate the electron and the heavy-hole adiabatic potentials with the local thickness of the layer. We present results of calculation of the exciton energies in uniform and non-uniform GaAs/Ga(Al)As quantum dots and rings, which are in a good accordance with the spectral features of excitons experimentally detected before in these structures. Our method should be applicable to wide range of problems, related to few carriers confined in quantum dots, for which any rigorous approach requires an extensive numerical work.

  18. Self-adaptive difference method for the effective solution of computationally complex problems of boundary layer theory

    Science.gov (United States)

    Schoenauer, W.; Daeubler, H. G.; Glotz, G.; Gruening, J.

    1986-01-01

    An implicit difference procedure for the solution of equations for a chemically reacting hypersonic boundary layer is described. Difference forms of arbitrary error order in the x and y coordinate plane were used to derive estimates for discretization error. Computational complexity and time were minimized by the use of this difference method and the iteration of the nonlinear boundary layer equations was regulated by discretization error. Velocity and temperature profiles are presented for Mach 20.14 and Mach 18.5; variables are velocity profiles, temperature profiles, mass flow factor, Stanton number, and friction drag coefficient; three figures include numeric data.

  19. Improving Segmentation of 3D Retina Layers Based on Graph Theory Approach for Low Quality OCT Images

    Directory of Open Access Journals (Sweden)

    Stankiewicz Agnieszka

    2016-06-01

    Full Text Available This paper presents signal processing aspects for automatic segmentation of retinal layers of the human eye. The paper draws attention to the problems that occur during the computer image processing of images obtained with the use of the Spectral Domain Optical Coherence Tomography (SD OCT. Accuracy of the retinal layer segmentation for a set of typical 3D scans with a rather low quality was shown. Some possible ways to improve quality of the final results are pointed out. The experimental studies were performed using the so-called B-scans obtained with the OCT Copernicus HR device.

  20. Radiative transfer theory for passive microwave remote sensing of a two-layer random medium with cylindrical structures

    Science.gov (United States)

    Chuang, S. L.; Kong, J. A.; Tsang, L.

    1980-01-01

    A model of the vegetation layer as a two-layer random medium with a small correlation length l sub rho in the horizontal direction, and a large correlation length l sub z in the vertical direction, is presented for fields with cylindrical structures. As l sub z approaches infinity, closed form solutions are derived for the brightness temperatures; the kernels in the scattering terms of the radiative transfer equations result in delta functions showing that forward scattering is dominant over all other directions. The results are compared with the Gaussian quadrature method data for numerical solution of the radiative transfer equations.

  1. Media Sociography on Weblogs

    DEFF Research Database (Denmark)

    Tække, Jesper

    to the media it is based on. Theoretically seen it is inspired of two theoretical paradigms the Sociological Systems Theory of Niklas Luhmann and the Media Theory (also called the Toronto school). Empirically the paper primary draws on the literature about weblogs, which could be framed as CMC......Weblogs are not only one of the newest technical media for communication, but also one of the most difficult to understand. Are weblogs a kind of mass medium, a personal medium like an online diary, or a medium that gives space for communities to grow? Or are weblogs a medium that enable all...... these possibilities depended on the actual use? This paper throws some light on what weblogs are by using the methodology of Media Sociography (Tække 2003, 2004a, 2004b and 2004c). Media Sociography is a strategy for analysing mediated social systems or in other words a strategy for describing the social in relation...

  2. Phase diagrams in mixed spin-3/2 and spin-2 Ising system with two alternative layers within the effective-field theory

    Institute of Scientific and Technical Information of China (English)

    Bayram Devirena; Yasin Polatb; Mustafa Keskinc

    2011-01-01

    The phase diagrams in the mixed spin-3/2 and spin-2 Ising system with two alternative layers on a honeycomb lattice are investigated and discussed by the use of the effective-field theory with correlations. The interaction of the nearest-neighbour spins of each layer is taken to be positive (ferromagnetic interaction) and the interaction of the adjacent spins of the nearest-neighbour layers is considered to be either positive or negative (ferromagnetic or antiferromagnetic interaction). The temperature dependence of the layer magnetizations of the system is examined to characterize the nature (continuous or discontinuous) of the phase transitions and obtain the phase transition temperatures. The system exhibits both second-and first-order phase transitions besides triple point (TP), critical end point (E), multicritical point (A), isolated critical point (C) and reentrant behaviour depending on the interaction parameters. We have also studied the temperature dependence of the total magnetization to find the compensation points,system. The phase diagrams are constructed in eight different planes and it is found that the system also presents the compensation phenomena depending on the sign of the bilinear exchange interactions.

  3. Density functional theory study of O-H and C-H bond scission of methanol catalyzed by a chemisorbed oxygen layer on Cu(111)

    Science.gov (United States)

    Li, Jonathan; Zhou, Guangwen

    2016-04-01

    Using the density-functional theory within the generalized gradient approximation, we have studied the partial oxidation of methanol on a Cu(111) surface covered with a chemisorbed oxygen layer that resembles a Cu2O layer. Adsorption energies and geometries were computed for methanol, methoxy, hydroxymethyl and formaldehyde on both clean Cu(111) and Cu2O/Cu(111) and electronic structures were computed for the reaction intermediates on Cu2O/Cu(111). We also calculated the energy barrier for partial oxidation of methanol to formaldehyde on Cu2O/Cu(111). These results show that the Cu2O monolayer slightly lowers the stability of each of the surface adsorbates and the oxygen strongly promotes hydrogen dissociation by lowering the energy barrier of methanol decomposition and causing the spontaneous dissociation of methanol into methoxy.

  4. Seeing the Fields and Forests: Application of Surface-Layer Theory and Flux-Tower Data to Calculating Vegetation Canopy Height

    Science.gov (United States)

    Pennypacker, Sam; Baldocchi, Dennis

    2016-02-01

    Canopy height is an important and dynamic site variable that affects the mass and energy exchanges between vegetation and the atmosphere. We develop a method to estimate canopy height routinely, using surface-layer theory and turbulence measurements made from a collection of flux towers. This tool is based on connecting the logarithmic wind profile generally expected in a neutral surface layer with direct measurements of friction velocity and assumptions about canopy height's relationships with zero-plane displacement and aerodynamic roughness length. Tests over a broad range of canopy types and heights find that calculated values are in good agreement with direct measurements of canopy height, including in a heterogeneous landscape. Based on the various uncertainties associated with our starting assumptions about canopy micrometeorology, we present a blueprint for future work that is necessary for expanding and improving these initial calculations.

  5. Longitudinal vibration of pile in layered soil based on Rayleigh-Love rod theory and fictitious soil-pile model

    Institute of Scientific and Technical Information of China (English)

    Lü Shu-hui; WANG Kui-hua; WU Wen-bing; C. J. LEO

    2015-01-01

    The dynamic response of pile in layered soil is theoretically investigated when considering the transverse inertia effect. Firstly, the fictitious soil-pile model is employed to simulate the dynamic interaction between the pile and the soil layers beneath pile toe. The dynamic interactions of adjacent soil layers along the vertical direction are simplified as distributed Voigt models. Meanwhile, the pile and fictitious soil-pile are assumed to be viscoelastic Rayleigh-Love rods, and both the radial and vertical displacement continuity conditions at the soil-pile interface are taken into consideration. On this basis, the analytical solution for dynamic response at the pile head is derived in the frequency domain and the corresponding quasi-analytical solution in the time domain is then obtained by means of the convolution theorem. Following this, the accuracy and parameter value of the hypothetical boundaries for soil-layer interfaces are discussed. Comparisons with published solution and measured data are carried out to verify the rationality of the present solution. Parametric analyses are further conducted by using the present solution to investigate the relationships between the transverse inertia effects and soil-pile parameters.

  6. Polarimetric signatures of a layer of random nonspherical discrete scatterers overlying a homogeneous half-space based on first- and second-order vector radiative transfer theory

    Science.gov (United States)

    Tsang, Leung; Ding, Kung-Hau

    1991-01-01

    Complete polarimetric signatures of a layer of random, nonspherical discrete scatterers overlying a homogeneous half space are studied with the first- and second-order solutions of the vector radiative transfer theory. Some of the salient features of the numerical results are as follows: (1) the inclusion of the nondiagonal extinction matrix in the vector radiative transfer theory accounts for an appreciable phase difference between vv and hh polarizations, particularly for aligned scatterers; (2) the ensemble-averaged scattered Stokes vector is generally partially polarized, with the degree of polarization less than unity; (3) there generally exists a pedestal in the copolarization return when plotted as a function of ellipticity and orientation angles, which may be due to heterogeneity of scattering objects and/or multiple scattering effects; and (4) multiple scattering effects generally enhance the pedestal in copolarization return, decrease the degree of polarization, affect phase difference, and also enhance the depolarization return.

  7. An Artificial Olfaction System Formed by a Massive Sensors Array Dispersed in a Diffusion Media and an Automatically Formed Glomeruli Layer

    Science.gov (United States)

    Di Natale, Corrado; Martinelli, Eugenio; Paolesse, Roberto; D'Amico, Arnaldo; Filippini, Daniel; Lundström, Ingemar

    2009-05-01

    Optical imaging is a read-out technique for sensors that can easily provide advances in artificial olfaction implementing features such as the large number of receptors and the glomeruli layer. In this paper an artificial olfaction system based on the imaging of a continuous layer of chemical indicators is illustrated. The system results in an array of thousands of sensors, corresponding to the pixels of the image. The choice of Computer Screen Photoassisted Technology as a platform for optical interrogation of the sensing layer allows for the definition of a strategy for an automatic definition of the glomeruli layer based on the classification of the optical fingerprints of the image pixels. Chemical indicators are dissolved into a polymeric matrix mimicking the functions of the olfactory mucosa. The system is here illustrated with a simple experiment. Data are treated applying a lateral inhibition to the glomeruli layer resulting in a dynamic pattern resembling that observed in natural olfaction.

  8. Multisided Media Markets

    DEFF Research Database (Denmark)

    Lindstädt, Nadine

    Media markets recently have been identified as multisided markets. The application of the theory of multisided markets provides a better understanding of such markets. It enriched the hitherto economic approach and led to new insights and perspectives especially for the antitrust authorities when...... evaluating competition constraints and mergers. This paper reviews the theory of multisided markets and subsequently applies it to media markets. Finally the paper draws attention to the new perspectives and insights the theory provides but also brings open research questions to light....

  9. Multisided Media Markets

    DEFF Research Database (Denmark)

    Lindstädt, Nadine

    Media markets recently have been identified as multisided markets. The application of the theory of multisided markets provides a better understanding of such markets. It enriched the hitherto economic approach and led to new insights and perspectives especially for the antitrust authorities when...... evaluating competition constraints and mergers. This paper reviews the theory of multisided markets and subsequently applies it to media markets. Finally the paper draws attention to the new perspectives and insights the theory provides but also brings open research questions to light....

  10. Effective material parameter retrieval for thin sheets: theory and application to graphene, thin silver films, and single-layer metamaterials

    CERN Document Server

    Tassin, Philippe; Soukoulis, Costas M; 10.1016/j.physb.2012.01.119

    2012-01-01

    An important tool in the field of metamaterials is the extraction of effective material parameters from simulated or measured scattering parameters of a sample. Here we discuss a retrieval method for thin-film structures that can be approximated by a two-dimensional scattering sheet. We determine the effective sheet conductivity from the scattering parameters and we point out the importance of the magnetic sheet current to avoid an overdetermined inversion problem. Subsequently, we present two applications of the sheet retrieval method. First, we determine the effective sheet conductivity of thin silver films and we compare the resulting conductivities with the sheet conductivity of graphene. Second, we apply the method to a cut-wire metamaterial with an electric dipole resonance. The method is valid for thin-film structures such as two-dimensional metamaterials and frequency-selective surfaces and can be easily generalized for anisotropic or chiral media.

  11. Effective material parameter retrieval for thin sheets: theory and application to graphene, thin silver films, and single-layer metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Tassin, Philippe; Koschny, Thomas; Soukoulis, Costas

    2012-01-30

    An important tool in the field of metamaterials is the extraction of effective material parameters from simulated or measured scattering parameters of a sample. Here we discuss a retrieval method for thin-film structures that can be approximated by a two-dimensional scattering sheet. We determine the effective sheet conductivity from the scattering parameters and we point out the importance of the magnetic sheet current to avoid an overdetermined inversion problem. Subsequently, we present two applications of the sheet retrieval method. First, we determine the effective sheet conductivity of thin silver films and we compare the resulting conductivities with the sheet conductivity of graphene. Second, we apply the method to a cut-wire metamaterial with an electric dipole resonance. The method is valid for thin-film structures such as two-dimensional metamaterials and frequency-selective surfaces and can be easily generalized for anisotropic or chiral media.

  12. Effective material parameter retrieval for thin sheets: Theory and application to graphene, thin silver films, and single-layer metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Tassin, Philippe, E-mail: tassin@ameslab.gov [Ames Laboratory - U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Koschny, Thomas, E-mail: koschny@ameslab.gov [Ames Laboratory - U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Soukoulis, Costas M., E-mail: soukoulis@ameslab.gov [Ames Laboratory - U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Institute of Electronic Structure and Lasers (IESL), FORTH, 71110 Heraklion, Crete (Greece)

    2012-10-15

    An important tool in the field of metamaterials is the extraction of effective material parameters from simulated or measured scattering parameters of a sample. Here we discuss a retrieval method for thin-film structures that can be approximated by a two-dimensional scattering sheet. We determine the effective sheet conductivity from the scattering parameters and we point out the importance of the magnetic sheet current to avoid an overdetermined inversion problem. Subsequently, we present two applications of the sheet retrieval method. First, we determine the effective sheet conductivity of thin silver films and we compare the resulting conductivities with the sheet conductivity of graphene. Second, we apply the method to a cut-wire metamaterial with an electric dipole resonance. The method is valid for thin-film structures such as two-dimensional metamaterials and frequency-selective surfaces and can be easily generalized for anisotropic or chiral media.

  13. 基于视觉传达原理的网页媒介设计%Webpage Media Design Based on the Theory of Visual Communication

    Institute of Scientific and Technical Information of China (English)

    李远林

    2012-01-01

    分析了网页的特点和优势。提出了将视觉传达原理运用在网页媒介中,能形成强大的视觉穿透力,提升网页的视觉效果。在此基础上,论述了网页设计中视觉穿透力的构建方法,从而促进了新的表现形式和设计形态的发展,使设计理念、流程和实践方法方面都发生了变革。%It analyzed the characteristics and advantages of webpage, put forward the theory of visual communication used in the webpage media, which can create a strong visual penetration and enhance the visual effects of the webpage. On this basis, it discussed the construction method of visual penetration in the webpage design, so as to promote the development of new form of expression and the design pattern, to make design concepts, processes and practices changed.

  14. On the theory of solitons of fluid pressure and solute density in geologic porous media, with applications to shale, clay and sandstone

    CERN Document Server

    Caserta, A; Salusti, E

    2016-01-01

    In this paper we propose the application of a new model of transients of pore pressure p and solute density \\r{ho} in geologic porous media. This model is rooted in the non-linear waves theory, the focus of which is advection and effect of large pressure jumps on strain (due to large p in a non-linear version of the Hooke law). It strictly relates p and \\r{ho} evolving under the effect of a strong external stress. As a result, the presence of quick and sharp transients in low permeability rocks is unveiled, i.e. the non-linear Burgers solitons. We therefore propose that the actual transport process in porous rocks for large signals is not the linear diffusion, but could be governed by solitons. A test of an eventual presence of solitons in a rock is here proposed, and then applied to Pierre Shale, Bearpaw Shale, Boom Clay and Oznam-Mugu silt and clay. A quick analysis showing the presence of solitons for nuclear waste disposal and salty water intrusions is also analyzed. Finally, in a kind of "theoretical exp...

  15. Studying the Regularities of High-Energy Flow Localization in Micro- and Nano-Layers at the Interface of Solid and Liquid Media

    Science.gov (United States)

    Mamaev, A. I.; Mamaeva, V. A.; Beletskaya, E. Yu.

    2017-08-01

    The paper presents the results of research performed by the modeling method and focusing on the distribution of material and energy flows at the interface of solid and liquid media under non-steady-state conditions. Modeling was performed using the case of two parallel oxidation-reduction reactions that occur under the impact of an external current supply of unlimited power. The identified regularities can be used when designing and arranging specific heterogeneous oxidation-reduction processes, in order to arrange local energy impact, including when one needs to form the nano-structured non-metallic inorganic coatings by microplasma method. Modeling demonstrates that nanosized localization of high-energy flows is possible at the media interface. Depending on pulse duration, the instantaneous energy can exceed the bond energy of chemical compounds. The identified regularities are true for description of non-steady-state heterogeneous oxidation-reduction reactions in chemistry, electrochemistry, catalysis and other areas of science and technology.

  16. Mass Media for Smoking Cessation in Adolescents

    Science.gov (United States)

    Solomon, Laura J.; Bunn, Janice Y.; Flynn, Brian S.; Pirie, Phyllis L.; Worden, John K.; Ashikaga, Takamaru

    2009-01-01

    Theory-driven, mass media interventions prevent smoking among youth. This study examined effects of a media campaign on adolescent smoking cessation. Four matched pairs of media markets in four states were randomized to receive or not receive a 3-year television/radio campaign aimed at adolescent smoking cessation based on social cognitive theory.…

  17. Peeling the layers: a grounded theory of interprofessional co-learning with residents of a homeless shelter.

    Science.gov (United States)

    E Rutherford, Gayle

    2011-09-01

    Clients, patients, families, and communities must be conceived as partners in care delivery, not just as recipients (D'Amour, D. & Oandasan, I. (2005). Journal of Interprofessional Care, 19(Suppl.), 8-20). Health-care students need an opportunity to understand community member self-determination, partnership, and empowerment (Scheyett, A., & Diehl, M. ( 2004 ). Social Work Education, 23(4), 435-450), within the frame of interprofessional education (IPE) where community members are involved as teachers and learners. The aim of this grounded theory research was to determine the conditions that support health-care students to learn with, from, and about community members. This study took place in a shelter for the homeless where nursing and social work students learned interprofessionally along with residents and clients of the shelter. Data were gathered through 7 months of participant observation, interviews, and focus groups. The interprofessional co-learning theory that emerged introduces the three phases of entering, engaging, and emerging, which co-learners experienced at different levels of intensity. This article outlines the conditions that support each of these phases of the co-learning process. This interprofessional co-learning theory provides a basis for further development and evaluation of IPE programs that strive to actively include community members as teachers and learners, experts, and novices together with service providers, students, and faculty members.

  18. Multi-layer hydrostatic equilibrium of planets and synchronous moons: theory and application to Ceres and to solar system moons

    Energy Technology Data Exchange (ETDEWEB)

    Tricarico, Pasquale [Planetary Science Institute, Tucson, AZ 85719 (United States)

    2014-02-20

    The hydrostatic equilibrium of multi-layer bodies lacks a satisfactory theoretical treatment despite its wide range of applicability. Here we show that by using the exact analytical potential of homogeneous ellipsoids we can obtain recursive analytical solutions and an exact numerical method for the hydrostatic equilibrium shape problem of multi-layer planets and synchronous moons. The recursive solutions rely on the series expansion of the potential in terms of the polar and equatorial shape eccentricities, while the numerical method uses the exact potential expression. These solutions can be used to infer the interior structure of planets and synchronous moons from their observed shape, rotation, and gravity. When applied to the dwarf planet Ceres, we show that it is most likely a differentiated body with an icy crust of equatorial thickness 30-90 km and a rocky core of density 2.4-3.1 g cm{sup –3}. For synchronous moons, we show that the J {sub 2}/C {sub 22} ≅ 10/3 and the (b – c)/(a – c) ≅ 1/4 ratios have significant corrections of order Ω{sup 2}/(πGρ), with important implications for how their gravitational coefficients are determined from fly-by radio science data and for how we assess their hydrostatic equilibrium state.

  19. Multi-Layer Hydrostatic Equilibrium of Planets and Synchronous Moons: Theory and Application to Ceres and to Solar System Moons

    CERN Document Server

    Tricarico, Pasquale

    2013-01-01

    The hydrostatic equilibrium of multi-layer bodies lacks a satisfactory theoretical treatment despite its wide range of applicability. Here we show that by using the exact analytical potential of homogeneous ellipsoids we can obtain recursive analytical solutions and an exact numerical method for the hydrostatic equilibrium shape problem of multi-layer planets and synchronous moons. The recursive solutions rely on the series expansion of the potential in terms of the polar and equatorial shape eccentricities, while the numerical method uses the exact potential expression. These solutions can be used to infer the interior structure of planets and synchronous moons from the observed shape, rotation, and gravity. When applied to dwarf planet Ceres, we show that it is most likely a differentiated body with an icy crust of equatorial thickness 30-90 km and a rocky core of density 2.4-3.1 g/cm$^3$. For synchronous moons, we show that the $J_2/C_{22} \\simeq 10/3$ and the $(b-c)/(a-c) \\simeq 1/4$ ratios have significa...

  20. Corporate Communication and Social Media

    OpenAIRE

    Serup, Liv; Laursen, Stine; Sandgreen, Michael; Trougaard, Victor; Lind, Line; Hansen, Camilla

    2012-01-01

    This project aims to explore the changes social media platforms have generated onto corporate communication. Exploring the notion of dialogue in relation to various dialogic theories, social media theory, and corporate communication will provide an answer to this, as the respective theories and concepts provide different perspectives. The analysis is anchored in a case study of Danske Bank and Call me, since they represent two well-established organizations on Facebook. It is concluded tha...

  1. Creative Digital Media Practices

    DEFF Research Database (Denmark)

    Frølunde, Lisbeth

    The presentation reviews the interplay of dialogic (Bakhtin, 1981) and multimodal theories on media production practices, with attention to visual communication (Kress and van Leeuwen, 2001, 2006). This theoretical approach aids in reflecting on digital media practices as novel (new) sign systems...... on collaboration (Benkler, 2006). The shift toward visual modes and digital media practices pose many pedagogical challenges for academics. I want to raise questions on how to teach “dialogically” with and through creative, digital media practices based on my plans for a course in Fall, 2011, where students...... develop a collaborative digital storytelling showcase for their own digital stories about Roskilde University. This course is intended to bring up reflections on the wider phenomenon of contemporary media practices, such as: YouTube, DIY (do-it-yourself) filmmaking or homemade, garage cinema (Jenkins...

  2. The Analysis and Strategy of the Competition between Media on Basis of Two-level Games Theory%媒介竞局的双层次博弈分析与对策

    Institute of Scientific and Technical Information of China (English)

    赵玉坤

    2011-01-01

    In this paper, around the competition among foreign media, the domestic media and the government agencies, the author use the methods of game theory to analyze the current development status and problems of the local media; facing the fierce competition, the local media must take effective measures to carry out the innovation of organizational structure, brand and management, so as to enhance the core competitiveness of China Media Group.%文章围绕媒介市场中“境外媒介-国内媒介-政府管理机构”三边参与的博弈竞局,运用博弈论的方法,分析当前本土媒介发展的现状和存在的问题;认为本土媒介在同境外媒介的竞争中,必须采取有效措施,进行组织结构创新、品牌产品创新、管理机制创新,从而提升中国传媒集团的核心竞争力.

  3. Ethical Analysis of the Functioning of Media in Society and Media Texts in the Classroom

    OpenAIRE

    Alexander Fedorov

    2015-01-01

    Ethical analysis of the functioning of media in society and media texts based on the ethical theory of media. It is assumed that the media are able to form certain audience’s moral principles. From this follows the main goal of media literacy ethics education: to involve the audience in a particular ethical behaviors (corresponding, for example, a particular religion, level of civilization, democracy, etc.). Teaching strategy is based on the study of ethical aspects of media and ethical analy...

  4. Quantitative phase imaging through scattering media

    Science.gov (United States)

    Kollárová, Vera; Colláková, Jana; Dostál, Zbynek; Slabý, Tomas; Veselý, Pavel; Chmelík, Radim

    2015-03-01

    Coherence-controlled holographic microscope (CCHM) is an off-axis holographic system. It enables observation of a sample and its quantitative phase imaging with coherent as well as with incoherent illumination. The spatial and temporal coherence can be modified and thus also the quality and type of the image information. The coherent illumination provides numerical refocusing in wide depth range similarly to a classic coherent-light digital holographic microscopy (HM). Incoherent-light HM is characterized by a high quality, coherence-noise-free imaging with up to twice higher resolution compared to coherent illumination. Owing to an independent, free of sample reference arm of the CCHM the low spatial light coherence induces coherence-gating effect. This makes possible to observe specimen also through scattering media. We have described theoretically and simulated numerically imaging of a two dimensional object through a scattering layer by CCHM using the linear systems theory. We have investigated both strongly and weakly scattering media characterized by different amount of ballistic and diffuse light. The influence of a scattering layer on the quality of a phase signal is discussed for both types of the scattering media. A strong dependence of the imaging process on the light coherence is demonstrated. The theoretical calculations and numerical simulations are supported by experimental data gained with model samples, as well as real biologic objects particularly then by time-lapse observations of live cells reactions to substances producing optically turbid emulsion.

  5. A finite parallel zone model to interpret and extend Giddings' coupling theory for the eddy-dispersion in porous chromatographic media.

    Science.gov (United States)

    Desmet, Gert

    2013-11-01

    The finite length parallel zone (FPZ)-model is proposed as an alternative model for the axial- or eddy-dispersion caused by the occurrence of local velocity biases or flow heterogeneities in porous media such as those used in liquid chromatography columns. The mathematical plate height expression evolving from the model shows that the A- and C-term band broadening effects that can originate from a given velocity bias should be coupled in an exponentially decaying way instead of harmonically as proposed in Giddings' coupling theory. In the low and high velocity limit both models converge, while a 12% difference can be observed in the (practically most relevant) intermediate range of reduced velocities. Explicit expressions for the A- and C-constants appearing in the exponential decay-based plate height expression have been derived for each of the different possible velocity bias levels (single through-pore and particle level, multi-particle level and trans-column level). These expressions allow to directly relate the band broadening originating from these different levels to the local fundamental transport parameters, hence offering the possibility to include a velocity-dependent and, if, needed retention factor-dependent transversal dispersion coefficient. Having developed the mathematics for the general case wherein a difference in retention equilibrium establishes between the two parallel zones, the effect of any possible local variations in packing density and/or retention capacity on the eddy-dispersion can be explicitly accounted for as well. It is furthermore also shown that, whereas the lumped transport parameter model used in the basic variant of the FPZ-model only provides a first approximation of the true decay constant, the model can be extended by introducing a constant correction factor to correctly account for the continuous transversal dispersion transport in the velocity bias zones.

  6. Photocatalytic reaction kinetics model based on electrical double layer theory Ⅲ.Surface complexation model of methyl orange adsorption on TiO2 surface

    Institute of Scientific and Technical Information of China (English)

    李新军; 李芳柏; 古国榜; 柳松; 王良焱; 梁园园

    2003-01-01

    Based on the infrared characterization of methyl orange adsorption on TiO2 surface and the titration of TiO2, the triple layer model of methyl orange adsorption on TiO2 was established according to electric double theory. The software FITEQL3.1 was applied to calculate the distribution of organic adsorption on TiO2 surface by introducing dummy components to help to overcome mathematical difficulties. It is shown that the chem. -adsorption species of methyl orange have a great adsorption amount. The adsorption constants of three kinds of surface complexation expressed as SOH+org-,SOH2org2 and SOHorg- are 5.98, 17.57 and -4.2, respectively.

  7. Media evolution and ‘epi-technic’ digital media: Media as cultural selection mechanisms

    DEFF Research Database (Denmark)

    Olesen, Mogens

    2016-01-01

    The explosive development of new digital media technologies is often described as a media evolution but hardly ever is the concept of ‘media evolution’ taken at face value. This article takes up that challenge by combining cultural evolution theories with medium theory. The article argues...... that biological selection mechanisms can provide an inroad into a new kind of historical and structural understanding of the relation between human culture and our technologies. In specific, human history is seen as a cultural evolution in which media technologies are the selection mechanisms....

  8. A new layer compound Nb{sub 4}SiC{sub 3} predicted from first-principles theory

    Energy Technology Data Exchange (ETDEWEB)

    Li Chenliang [School of Astronautics, Harbin Institute of Technology, Harbin (China); Kuo Jeilai [School of Physics and Mathematical Sciences, Nanyang Technological University (Singapore); Wang, Biao [School of Physics and Engineering, Sun Yat-Sen University, Guangzhou (China); Li Yuanshi [Department of Cardiology, First Clinical College, Harbin Medical University, Harbin (China); Wang Rui, E-mail: lichenliang1980@yahoo.com.c [Department of Applied Chemistry, Harbin Institute of Technology, Harbin (China)

    2009-04-07

    We predicted a new layer compound Nb{sub 4}SiC{sub 3} using the first-principles method. The structural stability, mechanical, electronic, theoretical hardness and optical properties of Nb{sub 4}SiC{sub 3} were investigated. A stable Nb{sub 4}SiC{sub 3} phase appears in the {alpha}-type crystal structure. Moreover, the predicted Nb{sub 4}SiC{sub 3} is a metal and exhibits covalent nature. Nb{sub 4}SiC{sub 3} has a theoretical hardness of 10.86 GPa, which is much higher than Nb{sub 4}AlC{sub 3}; at the same time, it is more ductile than Nb{sub 4}AlC{sub 3}. The strong covalent bonding in Nb{sub 4}SiC{sub 3} is responsible for its high bulk modulus and hardness. Nb{sub 4}SiC{sub 3} exhibits slightly anisotropic elasticity. Furthermore, its optical properties are also analysed in detail. It is shown that Nb{sub 4}SiC{sub 3} might be a better candidate material as a coating to avoid solar heating than Ti{sub 4}AlN{sub 3}.

  9. Media education.

    Science.gov (United States)

    Strasburger, Victor C

    2010-11-01

    The American Academy of Pediatrics recognizes that exposure to mass media (eg, television, movies, video and computer games, the Internet, music lyrics and videos, newspapers, magazines, books, advertising) presents health risks for children and adolescents but can provide benefits as well. Media education has the potential to reduce the harmful effects of media and accentuate the positive effects. By understanding and supporting media education, pediatricians can play an important role in reducing harmful effects of media on children and adolescents.

  10. Using self-consistent-field theory to understand enhanced steric stabilization by casein-like copolymers at low surface coverage in mixed protein layers.

    Science.gov (United States)

    Parkinson, Emma L; Ettelaie, Rammile; Dickinson, Eric

    2005-01-01

    We present a statistical mechanical approach to predicting the properties of mixed copolymer layers using the Scheutjens-Fleer self-consistent-field theory. Our model copolymers are based on the primary structures of the major bovine casein monomers, alpha(s1)-casein and beta-casein. Numerical calculations have been carried out to determine the polymer segment density profiles at an isolated hydrophobic surface and the interaction forces as a pair of polymer-coated surfaces is brought to close interlayer separation. For a copolymer model containing hydrophilic and hydrophobic segments, we show how the steric stabilizing capacity of a casein-like macromolecule at very low surface coverage is enhanced in the presence of a thin dense layer of shorter tethered amphiphilic chains. Using a more refined protein model, which also distinguishes between the charged and uncharged hydrophilic segments along the chain, we clearly demonstrate that the enhanced steric repulsion from beta-casein exceeds that from alpha(s1)-casein. These calculations explain how the replacement of just a few percent of beta-lactoglobulin by casein can inhibit the heat-induced thickening and flocculation behavior observed experimentally with some whey protein-stabilized oil-in-water emulsions.

  11. The electric double layer at a rutile TiO₂ water interface modelled using density functional theory based molecular dynamics simulation.

    Science.gov (United States)

    Cheng, J; Sprik, M

    2014-06-18

    A fully atomistic model of a compact electric double layer at the rutile TiO2(1 1 0)-water interface is constructed by adding protons to bridging oxygens or removing them from H2O molecules adsorbed on terminal metal cation sites. The surface charge is compensated by F(-) or Na(+) counter ions in outer as well as inner sphere coordination. For each of the protonation states the energy of the TiO2 conduction band minimum is determined relative to the standard hydrogen electrode by computing the free energy for the combined insertion of an electron in the solid and a proton in solution away from the double layer using density functional theory based molecular dynamics methods. Interpreted as electrode potentials, this gives an estimate of the capacitance which is compared to the capacitance obtained from the difference in the average electrostatic potentials in the solid and aqueous phase. When aligned at the point of zero charge these two methods lead to almost identical potential-charge profiles. We find that inner sphere complexes have a slightly larger capacitance (0.4 F m(-2)) compared to outer sphere complexes (0.3 F m(-2)).

  12. Finite frequency effects on apparent S-wave splitting in the D″ layer: comparison between ray theory and full-wave synthetics

    Science.gov (United States)

    Borgeaud, Anselme F. E.; Konishi, Kensuke; Kawai, Kenji; Geller, Robert J.

    2016-10-01

    We conduct a numerical experiment to investigate potential bias in measurements of S-wave splitting (apparent differences between the arrival times of SH and SV phases) for waves propagating close to the core-mantle boundary (CMB) in the D″ layer. The bias is defined as the discrepancy between shear wave splitting measured from finite frequency synthetic seismograms (`apparent splitting') and the splitting predicted by ray theory, which is a high-frequency approximation. For simple isotropic models, we find biases which are typically between 0.5 and 4 s, depending on the model, the Q structure and the dominant period of the synthetics. The bias increases for lower frequencies or lower Q values. The epicentral distance at which the bias starts depends on the frequency and the Q structure. We also compute synthetics for models based on mineral physics (using the elastic constants under lower-mantle pressure and temperature conditions, taking into account the phase transition from Mg-perovskite to Mg-post-perovskite) and geodynamics (the thermal boundary layer) and find that the depth of the positive velocity jump associated with the phase transition and the depth range over which the velocity decreases (due to temperature increases) in the thermal boundary layer significantly influence the wavefield in the lowermost mantle. For example, in cold regions beneath subduction zones, wavefields for SH and SV differ greatly due to the steep velocity decrease close to the CMB. For complex models, apparent splitting can also arise from the possibility that low amplitude direct phases might be overlooked, and larger amplitude later phases might instead incorrectly be picked as the direct arrival. Biases of the type investigated in this study combine with other sources of uncertainty for splitting in D″ (e.g. the correction for upper-mantle anisotropy and the difference between SH and SV ray paths) to make a precise evaluation of the anisotropy in D″ difficult.

  13. Finite frequency effects on apparent S-wave splitting in the D″ layer: comparison between ray theory and full-wave synthetics

    Science.gov (United States)

    Borgeaud, Anselme F. E.; Konishi, Kensuke; Kawai, Kenji; Geller, Robert J.

    2016-07-01

    We conduct a numerical experiment to investigate potential bias in measurements of S-wave splitting (apparent differences between the arrival times of SH and SV phases) for waves propagating close to the core-mantle boundary (CMB) in the D″ layer. The bias is defined as the discrepancy between shear wave splitting measured from finite frequency synthetic seismograms ("apparent splitting") and the splitting predicted by ray theory, which is a high-frequency approximation. For simple isotropic models, we find biases which are typically between 0.5 s and 4 s, depending on the model, the Q structure, and the dominant period of the synthetics. The bias increases for lower frequencies or lower Q values. The epicentral distance at which the bias starts depends on the frequency and the Q structure. We also compute synthetics for models based on mineral physics (using the elastic constants under lower mantle pressure and temperature conditions, taking into account the phase transition from Mg-perovskite to post-perovskite) and geodynamics (the thermal boundary layer) and find that the depth of the positive velocity jump associated with the phase transition and the depth range over which the velocity decreases (due to temperature increases) in the thermal boundary layer significantly influence the wavefield in the lowermost mantle. For example, in cold regions beneath subduction zones, wavefields for SH and SV differ greatly due to the steep velocity decrease close to the CMB. For complex models, apparent splitting can also arise from the possibility that low amplitude direct phases might be overlooked, and larger amplitude later phases might instead incorrectly be picked as the direct arrival. Biases of the type investigated in this study combine with other sources of uncertainty for splitting in D″ (e.g., the correction for upper mantle anisotropy and the difference between SH and SV raypaths) to make a precise evaluation of the anisotropy in D″ difficult.

  14. A Complete Reporting of MCNP6 Validation Results for Electron Energy Deposition in Single-Layer Extended Media for Source Energies <= 1-MeV

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hughes, Henry Grady [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-04

    In this paper, we expand on previous validation work by Dixon and Hughes. That is, we present a more complete suite of validation results with respect to to the well-known Lockwood energy deposition experiment. Lockwood et al. measured energy deposition in materials including beryllium, carbon, aluminum, iron, copper, molybdenum, tantalum, and uranium, for both single- and multi-layer 1-D geometries. Source configurations included mono-energetic, mono-directional electron beams with energies of 0.05-MeV, 0.1-MeV, 0.3- MeV, 0.5-MeV, and 1-MeV, in both normal and off-normal angles of incidence. These experiments are particularly valuable for validating electron transport codes, because they are closely represented by simulating pencil beams incident on 1-D semi-infinite slabs with and without material interfaces. Herein, we include total energy deposition and energy deposition profiles for the single-layer experiments reported by Lockwood et al. (a more complete multi-layer validation will follow in another report).

  15. An acoustic eikonal equation for attenuating VTI media

    KAUST Repository

    Hao, Qi

    2016-09-06

    We present an acoustic eikonal equation governing the complex-valued travel time of P-waves in attenuating, transversely isotropic media with a vertical symmetry axis (VTI). This equation is based on the assumption that the Pwave complex-valued travel time is independent of the Swave velocity parameter v in Thomsen\\'s notation and the attenuation coefficient A in the Thomsen-type notation for attenuating VTI media. We combine perturbation theory and Shanks transform to develop practical approximations to the attenuating acoustic eikonal equation, capable of admitting analytical description of the attenuation in homogeneous media. For a horizontal, attenuating VTI layer, we also derive non-hyperbolic approximations for the real and imaginary parts of the complex-valued reflection travel time.

  16. Restoring the consistency with the contact density theorem of a classical density functional theory of ions at a planar electrical double layer.

    Science.gov (United States)

    Gillespie, Dirk

    2014-11-01

    Classical density functional theory (DFT) of fluids is a fast and efficient theory to compute the structure of the electrical double layer in the primitive model of ions where ions are modeled as charged, hard spheres in a background dielectric. While the hard-core repulsive component of this ion-ion interaction can be accurately computed using well-established DFTs, the electrostatic component is less accurate. Moreover, many electrostatic functionals fail to satisfy a basic theorem, the contact density theorem, that relates the bulk pressure, surface charge, and ion densities at their distances of closest approach for ions in equilibrium at a smooth, hard, planar wall. One popular electrostatic functional that fails to satisfy the contact density theorem is a perturbation approach developed by Kierlik and Rosinberg [Phys. Rev. A 44, 5025 (1991)PLRAAN1050-294710.1103/PhysRevA.44.5025] and Rosenfeld [J. Chem. Phys. 98, 8126 (1993)JCPSA60021-960610.1063/1.464569], where the full free-energy functional is Taylor-expanded around a bulk (homogeneous) reference fluid. Here, it is shown that this functional fails to satisfy the contact density theorem because it also fails to satisfy the known low-density limit. When the functional is corrected to satisfy this limit, a corrected bulk pressure is derived and it is shown that with this pressure both the contact density theorem and the Gibbs adsorption theorem are satisfied.

  17. Critical Analysis of Media Violence Text on the Media Education Lessons

    Directory of Open Access Journals (Sweden)

    Alexander Fedorov

    2015-06-01

    Full Text Available The media violence is the important problem for education. Based on of Len Masterman’s media education theory of critical thinking and the methods of Umbeto Eco, the author of this article selected the following significant items for the analysis of media texts: author's ideology; socio-cultural, market and political environment, the process of creating a media text, audience perceptions, structure and narrative techniques. This approach is quite corresponds to the method of media texts analysis, building on media literacy education aspects such as media agencies, media / media text categories, media technologies, media languages, media representations and media audiences, because all these concepts are directly related to the ideological, socio-cultural and structural aspects.

  18. Density-functional theory for fluid mixtures of charged chain particles and spherical counterions in contact with charged hard wall: Adsorption, double layer capacitance, and the point of zero charge.

    Science.gov (United States)

    Pizio, O; Bucior, K; Patrykiejew, A; Sokołowski, S

    2005-12-01

    We consider a density-functional theory to describe nonuniform fluids composed of chain molecules, containing a charged segment each, and spherical counterions. The chain molecules are modeled as freely jointed chains of hard spheres, the counterions are oppositely charged spheres of the same diameter as all segments of chain molecules. The theory is applied to study the structure of adsorbed layers, the excess adsorption isotherms, the capacitance of the double layer, and the potential of the zero charge. We show that all electric properties are strongly dependent on the length of the chain molecules. Moreover, these properties are also dependent on the position of the charged segment in the chain.

  19. Strategies of teaching reform of Ideological and political theory course in colleges and universities under the new media era%新媒体时代下高校思政理论课教学改革策略

    Institute of Scientific and Technical Information of China (English)

    李娟

    2016-01-01

    随着科学技术的迅猛发展,对社会经济和生产发展有着重要作用的新媒体不断出现。由于高校大学生善于接受新媒体,所以新媒体对高校学生的学习生活有着非常明显的影响。但是,新媒体环境的形成,制约和影响高校思政理论课正常教学活动的开展,给高校思政理论课的教学带来了新的挑战。在新媒体时代环境下,对高校旧教学理念、教学方法及其教学手段等进行改革,是高校思想政治理论课取得有效成果的关键。因此,新媒体时代下高校思政理论课教学改革策略成为当下教育工作者所面临的重要课题。%With the rapid development of science and technology, the new media continue to emerge, which has important role to social economy and the production development. College students are good at accepting new media, so the new media has a great impact on their study and life. However, the formation of new media environment, restrict and influence the ideological and political theory teaching, also brings new challenges. In the environment under the new media era, the reform of university teaching ideas, teaching methods is the key of college ideological and political theory course to achieve effective results. Therefore, in the new media era, ideological and political theory course teaching reform strategy has become an important issue for the current education workers.

  20. Media Pedagogy: Media Education, Media Socialisation and Educational Media

    Directory of Open Access Journals (Sweden)

    Lars Qvortrup

    2007-07-01

    Full Text Available The aim of this paper is to examine the relationship between education and media. These two concepts can be combined in three ways: one can think of media education, i.e. education in the subject of mass media. One can think of media socialisation, i.e. education within the context of a media society in which pupils and students are experienced media users. Finally, one can think of educational media, i.e. media used for educational purposes.After having specified these three subject areas, the paper focuses on the third subject: Media used for educational purposes. According to the paper teaching can be defined as a specialised form of communication, and the basic point of the paper is that all communication is mediated. One cannot talk about such a thing as “non-mediated” communication. Also talking or touching implies media: Language or body language.Consequently, the introduction of new, digital media for teaching does not imply to make teaching more artificial or non-authentic. The introduction of new, digital media for teaching implies that other and older educational media are re-mediated.

  1. Media Komunitas dan Media Literacy

    Directory of Open Access Journals (Sweden)

    Pawito .

    2013-12-01

    Full Text Available Abstract:This essay deals with community media in relation to media literacy. After a short discussion on a number of community media characters is made the essay goes further with somewhat detail theoretical presumptions of the roles of media community with respect primarily to the development as Amartya Sen mentioned about. The author suggests that community media may play some significant roles in the development including (a disseminating information (from varieties of perspective, (b facilitating public discussion, (c helping to reach solutions of problems, (d encouraging participations, and (e encouraging the development of media literacy. Regarding the last point the author remarks that media community may have a dual-roles i.e facilitating community’s member in media participation and facilitating community’s member in media education.

  2. Comparison Between the Inhibition Efficiencies of Two Modification Processes with PEG-Ceria Based Layers Against Corrosion of Mild Steel in Chloride and Sulfate Media

    Science.gov (United States)

    Boudellioua, H.; Hamlaoui, Y.; Tifouti, L.; Pedraza, F.

    2017-08-01

    Cerium (III) and polyethylene glycol (PEG) combinations were employed to enhance the corrosion resistance of ASTM A915 mild steel in 0.1 M NaCl and in 0.1 M Na2SO4 media. One of the combinations consisted in dipping the steel in a bath mixture of PEG and cerium nitrate for 60 min. In the second combination, the steel was first immersed in the PEG solution for 30 min, then in cerium nitrate for 30 additional minutes. The corrosion protective capabilities of the superficially modified steels were evaluated through cyclic voltammetry, linear polarization resistance (R p), polarization measurements (Tafel) and electrochemical impedance spectroscopy. The composition and structure of the surface products were analyzed through Raman spectroscopy and scanning electron microscopy coupled to chemical EDS analysis. The mixture of PEG and cerium nitrate hindered the development of corrosion products on the mild steel surface. However, the subsequent immersion of the steel first in PEG then in cerium nitrate was not efficient to slow down corrosion.

  3. Media violence.

    Science.gov (United States)

    Strasburger, V C

    1999-01-01

    For decades, media violence has been viewed as largely a Western problem. New studies indicate that Indian children have increasing access to the media and that media violence will subject them to the same problems as Western children: imitation, desensitization, fear, and inappropriate attitudes about violence and aggression. Solutions exist but will have to be implemented within the next decade to protect Indian children and adolescents from the harmful effects of media violence.

  4. Media and ICT

    DEFF Research Database (Denmark)

    Media and information and communication technologies (ICTs) have in the past decades been placed firmly on the educational agenda, and will continue to maintain this position, not least as catalysts for educational change. This issue is reflected in the anthology as it aims to respond....... The multi- and transdisciplinary perspective is reflected in the learning theories of the articles, which are based on constructivist, situated and systems theories that in various ways relate to shared knowledge, workplace learning, collaborative learning and virtual learning communities....... to the question of how the presence of media and ICT in and outside schools both change and qualify educational practice as well as how the cooperation between media, cultures, aesthetics and social relations affect and support new demands on education. The book represents different academic perspectives...

  5. Public health and media advocacy.

    Science.gov (United States)

    Dorfman, Lori; Krasnow, Ingrid Daffner

    2014-01-01

    Media advocacy blends communications, science, politics, and advocacy to advance public health goals. In this article, we explain how media advocacy supports the social justice grounding of public health while addressing public health's "wicked problems" in the context of American politics. We outline media advocacy's theoretical foundations in agenda setting and framing and describe its practical application, from the layers of strategy to storytelling, which can illuminate public health solutions for journalists, policy makers, and the general public. Finally, we describe the challenges in evaluating media advocacy campaigns.

  6. Creative Digital Media Practices

    DEFF Research Database (Denmark)

    Frølunde, Lisbeth

    on collaboration (Benkler, 2006). The shift toward visual modes and digital media practices pose many pedagogical challenges for academics. I want to raise questions on how to teach “dialogically” with and through creative, digital media practices based on my plans for a course in Fall, 2011, where students......The presentation reviews the interplay of dialogic (Bakhtin, 1981) and multimodal theories on media production practices, with attention to visual communication (Kress and van Leeuwen, 2001, 2006). This theoretical approach aids in reflecting on digital media practices as novel (new) sign systems...... and personal levels. The discussion includes pedagogical issues in regards to the upcoming university course, such as: how to encourage dialogic reflection between students as authors and viewers of digital stories, and how to support their application and integration of visual and dialogic communication...

  7. SINGLE FRACTURE NUCLIDE TRANSPORT MODEL BASED ON THE DOUBLE MEDIA THEORY%基于双重介质理论的单裂隙核素迁移模型

    Institute of Scientific and Technical Information of China (English)

    李金轩; 李寻

    2001-01-01

    该文以基于双重介质理论的单裂隙迁移模型为基础,介绍裂隙介质中放射性核素迁移行为的模拟方法。并以实例说明该模型在高放废物处置库安全性能评价中的应用。%Based on the single fracture transport model from the double media theory, the paper introduces the simulation method of the radionuclide transport behavior in the fractured media. By a practical example, it states the application of the safety assessment of the model in high-level nuclear nuclear waste reposity.

  8. 全媒体与大学英语教学改革的理论与实践研究%Research on the theory and practice of whole media and university English teaching reform

    Institute of Scientific and Technical Information of China (English)

    闻蔚

    2013-01-01

    With the development of the media, to meet the requirements of students' learning, put forward the whole media of university English teaching theory, encourage students to use English learning network platform, to establish the English learning community, to improve English listening speaking reading writing and translation skills.%随着当今媒体的发展,适应学生的学习要求,提出全媒体大学英语教学改革的理论,鼓励学生利用英语学习网络平台,建立全英文英语学习社区,以提高英语听说读写译的各项技能。

  9. Media Technology

    Directory of Open Access Journals (Sweden)

    Zhou Gang

    2016-01-01

    Full Text Available Modern colleges are faced with the dual pressures of university reform and international competition, how to overcome difficulties, to play the role of modern English teaching in colleges and colleges to enhance the core competitiveness of colleges, colleges and colleges modern English teaching problems to be solved. Based on the current situation of modern colleges in the premise of the Modern media platform fully demonstrated the characteristics and viability of the Modern media English teaching, the necessity of modern English teaching of college Modern media. Discusses the Modern media targeting English teaching and important role is in the English teaching to guide the development of modern colleges modern media.

  10. 从媒介议程设置到受众自我设置:网络媒体议程设置理论的新特点%From the Media Agenda Setting to the Audience Self-setting:New Features of the Network Media Agenda Setting Theory

    Institute of Scientific and Technical Information of China (English)

    苗海洋

    2011-01-01

    网络媒体的发展大大改变了媒介环境,凭借数字化、多媒体、超文本的技术特征和多元化、个性化、交互性、快捷性、开放性和传播内容的丰富性等传播特征,网络媒体下的议程设置功能发生了显著变化,受众的匿名心理和角色扮演心理决定其对传播内容的选择不会完全受到传播者的影响,反而会根据自己的喜好、文化背景、价值观等形成"自我设置"。此外,本文认为,传统媒体中的某些新闻事件往往来源于网络,即网络媒体具有给传统媒体设置"议事日程"的功能。%The development of network media has dramatically changed the media environment.The network media has some new features different from traditional media,such as digitalization,multimedia,hypertext technical features and diversity,personalization,interactivity,promptness,openness and abundant content of communication.These features make the agenda setting theory undergo significant changes.Decided by the anonymous psychology and role-playing psychology,the audiences will not be completely affected by the disseminators when choosing the information they need,but will form the "self-setting" according to their own preferences,cultural background and values.In addition,some events reported by the traditional media firstly come from the network media,which indicates that the network media sets the agenda for the traditional media.

  11. Investigation of the structural anisotropy in a self-assembling glycinate layer on Cu(100) by scanning tunneling microscopy and density functional theory calculations

    Science.gov (United States)

    Kuzmin, Mikhail; Lahtonen, Kimmo; Vuori, Leena; Sánchez-de-Armas, Rocío; Hirsimäki, Mika; Valden, Mika

    2017-07-01

    Self-assembling organic molecule-metal interfaces exhibiting free-electron like (FEL) states offers an attractive bottom-up approach to fabricating materials for molecular electronics. Accomplishing this, however, requires detailed understanding of the fundamental driving mechanisms behind the self-assembly process. For instance, it is still unresolved as to why the adsorption of glycine ([NH2(CH2)COOH]) on isotropic Cu(100) single crystal surface leads, via deprotonation and self-assembly, to a glycinate ([NH2(CH2)COO-]) layer that exhibits anisotropic FEL behavior. Here, we report on bias-dependent scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations for glycine adsorption on Cu(100) single crystal surface. We find that after physical vapor deposition (PVD) of glycine on Cu(100), glycinate self-assembles into an overlayer exhibiting c(2 × 4) and p(2 × 4) symmetries with non-identical adsorption sites. Our findings underscore the intricacy of electrical conductivity in nanomolecular organic overlayers and the critical role the structural anisotropy at molecule-metal interface plays in the fabrication of materials for molecular electronics.

  12. Mechanism for the atomic layer deposition of copper using diethylzinc as the reducing agent: a density functional theory study using gas-phase molecules as a model.

    Science.gov (United States)

    Dey, Gangotri; Elliott, Simon D

    2012-09-06

    We present theoretical studies based on first-principles density functional theory calculations for the possible gas-phase mechanism of the atomic layer deposition (ALD) of copper by transmetalation from common precursors such as Cu(acac)(2), Cu(hfac)(2), Cu(PyrIm(R))(2) with R = (i)Pr and Et, Cu(dmap)(2), and CuCl(2) where diethylzinc acts as the reducing agent. An effect on the geometry and reactivity of the precursors due to differences in electronegativity, steric hindrance, and conjugation present in the ligands was observed. Three reaction types, namely, disproportionation, ligand exchange, and reductive elimination, were considered that together comprise the mechanism for the formation of copper in its metallic state starting from the precursors. A parallel pathway for the formation of zinc in its metallic form was also considered. The model Cu(I) molecule Cu(2)L(2) was studied, as Cu(I) intermediates at the surface play an important role in copper deposition. Through our study, we found that accumulation of an LZnEt intermediate results in zinc contamination by the formation of either Zn(2)L(2) or metallic zinc. Ligand exchange between Cu(II) and Zn(II) should proceed through a Cu(I) intermediate, as otherwise, it would lead to a stable copper molecule rather than copper metal. Volatile ZnL(2) favors the ALD reaction, as it carries the reaction forward.

  13. Accurate characterization and understanding of interface trap density trends between atomic layer deposited dielectrics and AlGaN/GaN with bonding constraint theory

    Energy Technology Data Exchange (ETDEWEB)

    Ramanan, Narayanan; Lee, Bongmook; Misra, Veena, E-mail: vmisra@ncsu.edu [Department of Electrical and Computer Engineering, North Carolina State University, 2410 Campus Shore Drive, Raleigh, North Carolina 27695 (United States)

    2015-06-15

    Many dielectrics have been proposed for the gate stack or passivation of AlGaN/GaN based metal oxide semiconductor heterojunction field effect transistors, to reduce gate leakage and current collapse, both for power and RF applications. Atomic Layer Deposition (ALD) is preferred for dielectric deposition as it provides uniform, conformal, and high quality films with precise monolayer control of film thickness. Identification of the optimum ALD dielectric for the gate stack or passivation requires a critical investigation of traps created at the dielectric/AlGaN interface. In this work, a pulsed-IV traps characterization method has been used for accurate characterization of interface traps with a variety of ALD dielectrics. High-k dielectrics (HfO{sub 2}, HfAlO, and Al{sub 2}O{sub 3}) are found to host a high density of interface traps with AlGaN. In contrast, ALD SiO{sub 2} shows the lowest interface trap density (<2 × 10{sup 12 }cm{sup −2}) after annealing above 600 °C in N{sub 2} for 60 s. The trend in observed trap densities is subsequently explained with bonding constraint theory, which predicts a high density of interface traps due to a higher coordination state and bond strain in high-k dielectrics.

  14. The differential susceptibility to media effects model

    NARCIS (Netherlands)

    Valkenburg, P.M.; Peter, J.

    2013-01-01

    In this theoretical article, we introduce the Differential Susceptibility to Media Effects Model (DSMM), a new, integrative model to improve our understanding of media effects. The DSMM organizes, integrates, and extends the insights developed in earlier microlevel media-effects theories. It

  15. The differential susceptibility to media effects model

    NARCIS (Netherlands)

    Valkenburg, P.M.; Peter, J.

    2013-01-01

    In this theoretical article, we introduce the Differential Susceptibility to Media Effects Model (DSMM), a new, integrative model to improve our understanding of media effects. The DSMM organizes, integrates, and extends the insights developed in earlier microlevel media-effects theories. It disting

  16. The differential susceptibility to media effects model

    NARCIS (Netherlands)

    Valkenburg, P.M.; Peter, J.

    2013-01-01

    In this theoretical article, we introduce the Differential Susceptibility to Media Effects Model (DSMM), a new, integrative model to improve our understanding of media effects. The DSMM organizes, integrates, and extends the insights developed in earlier microlevel media-effects theories. It disting

  17. Deposition of selenium thin layers on gold surfaces from sulphuric acid media: Studies using electrochemical quartz crystal microbalance, cyclic voltammetry and AFM

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Murilo Feitosa [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, C.P. 780, 13566-590 Sao Carlos, SP (Brazil); Pedrosa, Valber A., E-mail: vzp0002@auburn.ed [Department of Materials Engineering, Samuel Ginn College of Engineering, Auburn University, Auburn, AL 36849 (United States); Spinola Machado, Sergio Antonio [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, C.P. 780, 13566-590 Sao Carlos, SP (Brazil)

    2010-01-01

    In this paper we report here new considerations about the relationship between the mass and charge variations (m/z relationship) in underpotential deposition (UPD), bulk deposition and also in the H{sub 2}Se formation reaction. Nanogravimetric experiments were able to show the adsorption of H{sub 2}SeO{sub 3} on the AuO surface prior to the voltammetric sweep and that, after the AuO reduction, 0.40 monolayer of H{sub 2}SeO{sub 3} remains adsorbed on the newly reduced Au surface, which was enough to gives rise to the UPD layer. The UPD results indicate that the maximum coverage with Se{sub ads} on polycrystalline gold surface corresponds to approximately 0.40 monolayer, in good agreement with charge density results. The cyclic voltammetry experiments demonstrated that the amount of bulk Se obtained during the potential scan to approximately 2 Se monolayers, which was further confirmed by electrochemical quartz crystal microbalance (EQCM) measurements that pointed out a mass variation corresponding of 3 monolayers of Se. In addition, the Se thin films were obtained by chronoamperometric experiments, where the Au electrode was polarized at +0.10 V during different times in 1.0 M H{sub 2}SO{sub 4} + 1.0 mM SeO{sub 2}. The topologic aspects of the electrodeposits were observed in Atomic Force Microscope (AFM) measurements. Finally, in highly negative potential polarizations, the H{sub 2}Se formation was analyzed by voltammetric and nanogravimetric measurements. These finding brings a new light on the selenium electrodeposition and point up to a proposed electrochemical model for molecule controlled surface engineering.

  18. Study on "Self-media era" from the Perspective of Bakhtin's Carnivalesque Theory%从巴赫金狂欢化理论看“自媒体时代”

    Institute of Scientific and Technical Information of China (English)

    王琦予

    2012-01-01

    随着信息技术的高速发展,传统大众媒体的许多功能被新兴媒体所取代。媒介形式的多元化和新媒体所具有的海量、交互、超时空等特性使新的传播范式中"人"本身成为传播的主体,个人表达得到充分的体现。此外,当前草根文化展现出一场百花齐放的平民狂欢盛宴。人与人、社会之间的交流互动进入了一个崭新的时代,即通过新兴媒体达到表达自我这一目的的"自媒体时代"。通过对巴赫金狂欢化理论的梳理与拓展,讨论了自媒体时代背景下的草根狂欢这一社会热点问题。%Thanks to the rapid development of IT,traditional mass media are replaced by new high-technological media like Internet.With the diversification of media forms and the new communicating paradigm,in the new high-technological media with the characteristic of massive,interactive and trans-time-and-space information,the "person" himself becomes the main subject of spreading and individual expression is fully reflected.In addition,currently,"grassroot" culture stands out on the internet and blossoms to a popular carnival feast.At this point,the interaction between people,society and the world has entered a new era——"self-media era",an era to express self-purpose through the new media.We try to expand and develop Bakhtin 's theory,and discusses this social focus grassroots carnival under the background of "self-media era".

  19. Aesthetic Analysis of Media Texts in the Classroom at the Student Audience

    Science.gov (United States)

    Fedorov, Alexander

    2015-01-01

    Aesthetic analysis of media texts, ie the analysis of art concept of the media texts of different types and genres, is closely related to the aesthetic (artistic) theory of media (Aesthetical Approach, Media as Popular Arts Approach, Discriminatory Approach). Aesthetic theory of media literacy education has been very popular in the 1960s…

  20. Framing theory

    NARCIS (Netherlands)

    de Vreese, C.H.; Lecheler, S.; Mazzoleni, G.; Barnhurst, K.G.; Ikeda, K.; Maia, R.C.M.; Wessler, H.

    2016-01-01

    Political issues can be viewed from different perspectives and they can be defined differently in the news media by emphasizing some aspects and leaving others aside. This is at the core of news framing theory. Framing originates within sociology and psychology and has become one of the most used th