Wagner Theories Research Articles

Physicochemical, morphological, and charge carrier mobility range dielectric evaluations of Yb-doped BaCo2 W-type hexagonal ferrites for high-frequency applications

Microwave absorption materials have attracted attention due to their extensive applications in different fields. Herein, ytterbium-doped BaCo2 W-type hexaferrite nanocrystallites with a nominal composition of BaCo2YbxFe16−xO27 (x = 0.00, 0.03, 0.06, 0.09, and 0.12) were synthesized via the sol–gel method, and their physicochemical and dielectric characteristics were estimated. XRD plots revealed the pure phase structure of each prepared hexaferrite sample. The lattice constant and unit cell volume were affected by changes in the Yb concentration. The crystallite size was measured by the Debye–Scherrer formula, revealing intense crystals typically in the 18–33 nm range. FTIR spectroscopy showed multiple absorption bands from 430 to 3000 cm−1, and Raman spectroscopy revealed multiple peaks between 200 and 1000 cm−1, displaying the allocated polyhedra and symmetry. XPS spectroscopy confirmed the existence of all metal ions in the required valence state. The dielectric measurements were evaluated at frequencies from 1 to 6 GHz for all the synthesized compositions, and the material behavior was explained using the Maxwell–Wagner and Koop theories. The conduction mechanism in the hexagonal ferrites was assessed using Cole–Cole analysis. Reflection loss measurements were also conducted: the samples at x = 0.03 and x = 0.12 yielded minimal reflection losses of −60.06 and −51.69 dB at 5.5 GHz, respectively. The results demonstrate the suitability of the samples for use in microwave and high-frequency absorption applications.

Characteristics of Slamming Pressure and Force for Trimaran Hull

In this paper, the characteristics of the impact pressure and force of a trimaran section was studied by Computational Fluid Dynamics (CFD). The time domain features of the slamming pressure or force showed a strong correlation with the penetration depth regardless of the specific ways of water entry. The effects of velocity and acceleration on the impact pressure and force were analyzed. It was found that the initial impact of the main hull and the wet-deck slamming were predominantly affected by the entry velocities, whilst the acceleration had almost no effect for initial impact. The impact velocity presented a quadratic relation with slamming pressure/forces, and the relation between acceleration and wet-deck slamming pressure/force was linear. These were consistent with the patterns implied by analytical models such as the Wagner or MLM (Modified Logvinovich model) theories.

Analysis of hydroelastic slamming of flexible structures: modeling and experiments

With the growing interest in the integration of lightweight composite materials in marine vessels, the study of hydroelastic slamming becomes of paramount importance. Here, we propose an integrated theoretical and experimental approach to elucidate the physics of slamming during both the water entry and exit of flexible wedges. The deformation of the wedge is described through Euler-Bernoulli beam theory and the fluid flow is modelled using a combination of the classical Wagner and von Karman theories. Experiments are conducted on a wedge with 25° deadrise angle, whose motion is controlled using a pneumatic control system. The pressure field in the fluid is reconstructed from particle image velocimetry data by integrating incompressible Navier-Stokes equations. Experimental results confirm that the free surface elevation during water exit is significantly different than entry and the pressure is larger than the atmospheric pressure during water entry, while it may be less than atmospheric pressure during the exit stage.

Wagner and Literature: New Directions: Introduction

Many readers of this Special Issue will be aware of the plethora of events in 2013 marking the 200th anniversary of the birth of Richard Wagner (1813–83). In addition to several international conferences and symposia at the Sibelius Academy in Helsinki, the Freud Museum in London, and the universities of Alcalá, Leeds, Leipzig, Melbourne and Toronto (plus the multi-year ‘WagnerWorldWide’ programme organized by the University of Bayreuth), there have been Ring cycles in Berlin, Copenhagen, Frankfurt, Hamburg, Longborough, Mannheim, Melbourne, Milan, Munich, New York, Paris, Seattle, Sofia and Vienna, along with the more populist ‘Rhinegold on the Rhine’ (involving a floating musical theatre) and Gregor Seyffert's colourful Leipzig dance spectacular ‘Wagner Reloaded’. The range of concerts, films and symposia associated with the ‘Wagner 200’ Festival in London alone suggests how fascinating and relevant Wagner remains for contemporary audiences and scholars. Unsurprisingly, 2013 also produced significant additions to an already vast Wagner literature: whether the wide-ranging Cambridge Wagner Encyclopedia, monographs with a biographical, philosophical or cultural focus, or collected essays, book chapters and journal articles on topics such as the reception history of Wagner in France and Eastern Europe, a revisiting of Wagner's racial theories, cultural, aesthetic, gender and performance issues, and analytical and contextual studies of specific compositions.1

Coarsening process of coherent β′ precipitates in Fe–10 wt-%Ni–15 wt-%Al and Fe–10 wt-%Ni–15 wt-%Al–1 wt-%Cu alloys

The coarsening process of the NiAl ordered β′ precipitates was studied in the isothermally aged Fe–10 wt-%Ni–15 wt-%Al and Fe–10 wt-%Ni–15 wt-%Al–1 wt-%Cu alloys. The aging treatments at 750, 850 and 950°C caused the precipitation of the β′phase in a ferritic matrix. In general, the coarsening process of Cu containing alloy was slower with an activation energy of 248 kJ mol−1 compared to 194 kJ mol−1 for the other alloy. However, the coarsening kinetics for the former alloy was faster at 950°C. The precipitation hardening response was also better in the Cu containing alloy, with a slower overaging stage. The coarsening kinetics followed the behaviour predicted by the modified Lifshitz–Slyozov–Wagner theories for coarsening controlled by volume diffusion.

‘A Wagner for the Jews’: Moses Pergament, Richard Wagner and anti-Semitism in Swedish cultural life in the interwar period

This article deals with the Finnish-Swedish, Jewish composer and author Moses Pergament and his relationship with Wagner's theories, anti-Semitism in particular, and their influence on the development of modern Swedish classical music during the interwar period. The author emphasizes the importance of recognizing that Pergament's reaction to Wagner's cultural theories was part and parcel of his struggle for assimilation. The basis of Pergament's interpretation of Wagner was the notion that it is possible to separate life and belief: the anti-Semitism and enthusiastic lechery were part of Wagner's life, to which it was not necessary to attach much importance. The beliefs, on the other hand, were there to be analysed. Furthermore, an explicit and public critique of Wagner's anti-Semitism was inconsistent with an attempt to gain a foothold in Swedish cultural life. As Wagner's anti-Semitism was well known but was deemed either acceptable or irrelevant, paying attention to it was by definition proof of a Jewish identification. To be accepted as a Swedish music critic, Pergament had to follow the unwritten rules of the game, amongst them the requirement not to exhibit his ‘Jewishness’ openly. The actions of certain members of Föreningen Svenska Tonsättare (FST, the Association of Swedish Composers) indicate that Pergament's work was not thought to indicate a Swedish identification. On the contrary, his reviews were seen as a threat to ‘Swedish music’, and with implicit references to Wagner this was attributed to Pergament's supposed lack of feeling for the ‘spirit of the Swedish people’.

Hydroelastic analysis of bodies that enter and exit water

The entry and exit of flexible bodies through an air–water interface is studied using a tightly coupled fluid–structure interaction solver. The fluid domain is modeled using finite-volume CFD and the flexible structure is represented by a modal basis. The current work uses finite elements to generate the structural mode shapes and frequencies. The modal description allows for a reduction in structural degrees of freedom to reduce computation time. A linearized boundary condition is used on the mutual interface to eliminate mesh deformation. The accuracy of the method is quantified using the constant-velocity-wedge-impact problem. The quality of the fluid solution for the entry and exit problem is evaluated using a rigid wedge case and comparison to Von Karman and Wagner theories. Finally, the response of an elastic wedge during entry and exit is studied with the fluid–structure interaction solver. The results are used to assess two common approximations, namely the rigid-quasi-static and rigid-dynamic approximations. It is shown that for entry and exit, hydroelastic effects may be important for a wide range of loading conditions.

Wagner, Klimt, and the Metaphysics of Creativity in fin-de-siècle Vienna

This article takes a close look at a pair of well-known works by Gustav Klimt, the Nuda Veritas (1898) and the Beethoven Frieze (1902), and argues that the Schopenhauerian worldview evident in them testifies to the underappreciated influence of Richard Wagner on the Viennese artistic scene circa 1900. I begin by isolating previously unnoticed strains of Schopenhauerian iconography evident in the Nuda Veritas pertaining to the source and value of artistic creativity. I proceed by demonstrating that Klimt's peculiar use of that iconography conflicts with Schopenhauer's own theories of art, although it hews closely to Wagner's idiosyncratic interpretation of Schopenhauer's ideas outlined in his Beethoven essay and enacted in Die Meistersinger von Nürnberg. After surveying evidence of Klimt's familiarity with Wagner's works, I turn to Die Meister singer, highlighting the unacknowledged ways in which that opera dramatically enacts Wagner's theories of creativity. I conclude by suggesting that some of those same theories underlie the imagery of Klimt's Beethoven Frieze, and by suggesting more broadly that the Beethoven Frieze and the Nuda Veritas testify to the vital role played by Wagner's music dramas in mediating and popularizing a quasi-Schopenhauerian worldview in the creative culture of the turn of the century.

Evolution of Colloidal Nanocrystals: Theory and Modeling of their Nucleation and Growth

Through the use of a population balance equation (PBE), the nucleation and growth of nanocrystals evolving under various initial reaction conditions are simulated. Simulations of nanocrystal (NC) growth in both the diffusion and reaction limits are presented, and it is concluded that NC growth proceeds under strongly reaction-limited kinetics. The particle size distributions obtained in the asymptotic diffusion and reaction limits were found to be slightly narrower than the stationary distributions predicted by LSW and Wagner theories, respectively. There is strong experimental evidence indicating that the early stages of NC synthesis involve simultaneous nucleation, growth and coarsening. The simulations performed here are able to replicate these conditions, providing insight into the factors that govern these early time processes, as well as the consequences they have at longer reaction times.

Richter's Wagner: a new source for tempi in Das Rheingold

AbstractDespite the number of musicological studies that have focused upon Wagner's theories of tempo modification, the basic speeds adopted in early performances of Wagner's music dramas have been more difficult to identify. This article focuses upon an important new source of information concerning Wagnerian performance – a list of metronome timings made by Edward Dannreuther at the first dress rehearsal of Das Rheingold at Bayreuth in July 1876. After considering the practical difficulties of tempo measurement, and briefly placing the broad implications of Dannreuther's timings in the context of Wagner's theories and practice, the dress rehearsal tempi are examined in more detail in terms of their potential for practical realisation in performance. Six readings of Das Rheingold from the recorded canon (Bodanzky, Furtwängler, Knappertsbusch, Solti, Karajan, Boulez) provide a suitable comparative perspective from which to discuss how these tempi might affect perceptions of physical distance, the nature of motifs related to characters or events, tempo relationships within a musical scene, and larger-scale tempo connections in Das Rheingold as a whole. In particular, the very quick tempi identified by Dannreuther (especially in relation to modern sensibilities) might encourage a reassessment of practical possibilities in the realisation of Wagner's scores, along with a reconsideration of Wagner's music and its meanings.I know of no conductor whom I could trust to perform my music correctly … on the evening of the final performance of Twilight of the Gods in Bayreuth … what … had reduced me to such despair … was my horror at realizing that my conductor [Hans Richter] – in spite of the fact that I consider him the best I know – was not able to maintain the correct tempo, however often he got it right, because – he was incapable of knowing why the music had to be interpreted in one way and not another. – For this is the very heart of the matter: anyone may succeed by chance at least once, but he is not aware of what he is doing, – for I alone could have justified it by means of what I call my school.1I am persistently returning to the question of tempo because, as I said before, this is the point at which it becomes evident whether a conductor understands his business or not.2

Electrorotation of beads of immobilized cells

Electrorotation spectra were recorded for single yeast cells, microbeads (<90 μm) containing different concentrations of immobilized yeast cells within a κ-carrageenan matrix, and yeast clumps obtained by flocculation. It was found that, at the low medium conductivities used, the electrorotation spectra of κ-carrageenan beads containing immobilized yeast cells had a single peak, and were essentially the same as the electrorotation spectra of cell-free microbeads. Increasing the yeast concentration had no effect on the spectra. In contrast, the electrorotation spectra of clumps of flocculated yeast had a clockwise as well as an anti-clockwise peak, and were similar to those of single yeast cells. It is proposed that in beads with flocculated cells the cell–cell contacts cause the cells to form effectively a continuous cell layer with medium dispersed between the cells. This is in contrast with the gel beads, where little cell–cell contact occurs, and the gel forms a continuous phase between the yeast cells. Based on these assumptions a simple model is described based on Maxwell–Wagner's theories of interfacial polarization, in which the continuous and dispersed phase are reversed.

Oblique slamming, planing and skimming

This paper describes how tangential impact velocities can be incorporated into well-known impact theories in deep and shallow water. Taking the deep and shallow flows in turn, it is shown how to link the normal impact Wagner and Korobkin theories to the tangential impact theories of planing and skimming, respectively. An instability is revealed that limits the configurations that can be analysed in the deep water case when the angle of impact is comparable to the deadrise angle. Most of the discussion is confined to two-dimensional flow but a model is also proposed that may describe the spray sheets that can be generated in three-dimensional skimming.

AC electrokinetic characterisation and separation of cells with high and low embryogenic potential in suspension cultures of carrot (Daucus carota)

Suspension cultures of Daucus carota L. were established, and cells with embryogenic potential were separated from those without by density gradient centrifugation in Ficoll at different stages in the growth curve. In order to obtain information about the electrical properties of individual cells, electrorotation spectra of single plant cells from different fractions were measured before and after induction of embryogenesis. The data were analysed using models based on Maxwell–Wagner's theories of interfacial polarisation. It was found that the denser cells had a higher embryogenic potential, a darker appearance and a higher internal conductivity (>1 S m−1) than the less dense cells, which had less or no embryogenic potential and a lower internal conductivity (<1 S m−1). Modelling the dielectrophoretic (DEP) response on the basis of the electrorotation data suggested that separation of cells with high embryogenic potential may be achievable in the frequency range 1–10 MHz. Actual dielectrophoretic separation of cells with high embryogenic potential from suspensions in which embryogenesis had not yet been induced was achieved using steric as well as hyperlayer dielectrophoretic Field-Flow Fractionation (DEP-FFF).

Effect of the surface conductance on electrokinetic potential measured in nonaqueous media

The effect of the surface conductance on the ζ-potential of dispersed particles determined from their electrophoretic mobility in nonaqueous electrolyte solutions was considered. The conductivity of dilute quartz suspensions and the electrophoretic mobility of quartz particles in NaBr solutions in butanol-1 and dimethyl sulfoxide as well as in LiBr solutions in acetone at the salt concentration C= 10–5–10–2M were determined by conductometry and microelectrophoresis. The dependences of surface conductivity and ζ-potential on the electrolyte content were calculated by formulas of the Wagner and Henry theories. It was shown that, in the region of dilute solutions, ζ(log C) curves thus obtained significantly differ from corresponding functions calculated by the Smoluchowski equation. At the same time, these dependences agreed closely with the ζ(log C) dependences determined for the same systems by the streaming potential method with allowances for experimental values of the surface conductivity. Using aluminum oxide suspensions in NaBr and HBr ethanol solutions as examples, it was shown that, to obtain correct values of the ζ-potential from electrophoretic mobility of porous particles impregnated with a solution, it is necessary to allow for the bulk conductance of the particles.

An extended Maxwell–Wagner theory for the electric birefringence of charged colloids

Recent frequency resolved electric birefringence experiments on dilute suspensions of charged, ellipsoidal particles reveal new relaxation features in the MHz frequency range. Such behavior can be explained in terms of surface transport processes. Here we develop a model for the electric polarizability of spheroidal particles by combining features of electrokinetic and Maxwell–Wagner theories. The model accurately depicts the high frequency features and relates them to the colloidal properties of the polyelectrolyte. Using the model, particle charge can be extracted from electric birefringence measurements.

Experimental evaluation of particle coarsening theories

Experiments have been carried out on coarsening of γ″ precipitates in Ni–Al and Ni–Al–Cr alloys and rate constants and particle size distributions have been determined as a function of volume fraction of γ″. These results have been compared with those predicted by the various modified Lifshitz–Slyozov–Wagner theories. An important result obtained in this investigation is that the growth rate constant increases with volume fraction of γ″ in the Ni–Al system. The Brailsford–Wynblatt encounter model has been applied to the coarsening data obtained in the Ni–Al and the Ni–Al–Cr systems and values of interfacial energies and activation energies have been determined. By applying the growth path envelope analysis to the γ′ coarsening data obtained in the Ni–Al system the ratio of the mean particle radius to the critical particle radius R/Rc and the variation of the growth rate of the particle with particle size have been determined.MST/1036

Experimental evaluation of particle coarsening theories

AbstractExperiments have been carried out on coarsening of γ″ precipitates in Ni–Al and Ni–Al–Cr alloys and rate constants and particle size distributions have been determined as a function of volume fraction of γ″. These results have been compared with those predicted by the various modified Lifshitz–Slyozov–Wagner theories. An important result obtained in this investigation is that the growth rate constant increases with volume fraction of γ″ in the Ni–Al system. The Brailsford–Wynblatt encounter model has been applied to the coarsening data obtained in the Ni–Al and the Ni–Al–Cr systems and values of interfacial energies and activation energies have been determined. By applying the growth path envelope analysis to the γ′ coarsening data obtained in the Ni–Al system the ratio of the mean particle radius to the critical particle radius R/Rc and the variation of the growth rate of the particle with particle size have been determined.MST/1036

Two-Dimensional Water-Solid Impact

Abstract The general problem of a two-dimensional water-solid impact is considered. The method of matched asymptotic expansions is used to solve the resulting boundary value problem for small penetration depth. The first-order solution obtained extends the classical Von Ka´rma´n and Wagner theories to non-normal impact and initially curved free surfaces. It accounts for nonlinear features such as the creation of a jet at each waterline. The application of the method to the computation of the impact loads exerted by spilling breakers on a marine structure is discussed.

Effects of Scale Porosity, Second‐Phase Oxides, and Doping in the High‐Temperature Oxidation of Cobalt and Dilute Cobalt‐Chromium Alloys

The oxidation mechanisms of high‐purity cobalt and dilute Co‐Cr alloys have been investigated over a 950°–1350°C temperature range in oxygen atmospheres of 10–760 Torr. The 99.999% cobalt exhibited parabolic oxidation behavior for weight gains of up to 30 mg oxygen/cm2 rectangular specimen surface. Parabolic kinetics were interrupted when fissures developed in the oxide scale as a result of mechanical stresses at the metal/scale interface or through anisotropic decomposition along grain boundaries. Molecular oxygen then short‐circuited to the porous inner scaling layer in accelerated attack of fresh Co surfaces. Diffusion of Co2+ through the scale is considered to be the primary rate determining process during periods of steady‐ state oxidation. The effect of porosity at the metal/scale interface prior to perforation of the outer scaling layer is slight, but is believed to result in a small reduction of the oxidation rate due to a reduction in the contact surface through which cations enter the oxide. Co alloys containing 0.5, 3, 7, and 10 w/o (weight per cent) Cr also obey parabolic kinetics during formation of thinner scaling layers. Porosity and localized loss of scale adherence are aggravated by the presence of and particles in the inner scaling layer to the extent that scale rupture mechanisms quickly obscure parabolic kinetics for chromium contents greater than 3 w/o at temperatures of 1150°C and above in 100 Torr oxygen. Under conditions where initial periods of steady‐state parabolic oxidation were discernible on thermobalance curves, maximum reaction kinetics are associated with 1–2 w/o Cr additions (which approach the Cr3+ solubility limit in ) as rationalized by Wagner's semiconductor valence theories.