6,403 research outputs found

    Protection from Government Disclosure

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    Correlations of electromagnetic fields in chaotic cavities

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    We consider the fluctuations of electromagnetic fields in chaotic microwave cavities. We calculate the transversal and longitudinal correlation function based on a random wave assumption and compare the predictions with measurements on two- and three-dimensional microwave cavities.Comment: Europhys style, 8 pages, 3 figures (included

    Scaling behavior of a one-dimensional correlated disordered electronic System

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    A one-dimensional diagonal tight binding electronic system with correlated disorder is investigated. The correlation of the random potential is exponentially decaying with distance and its correlation length diverges as the concentration of "wrong sign" approaches to 1 or 0. The correlated random number sequence can be generated easily with a binary sequence similar to that of a one-dimensional spin glass system. The localization length (LL) and the integrated density of states (IDOS) for long chains are computed. A comparison with numerical results is made with the recently developed scaling technique results. The Coherent Potential Approximation (CPA) is also adopted to obtain scaling functions for both the LL and the IDOS. We confirmed that the scaling functions show a crossover near the band edge and establish their relation to the concentration. For concentrations near to 0 or 1 (longer correlation length case), the scaling behavior is followed only for a very limited range of the potential strengths.Comment: will appear in PR

    Statistics of the electromagnetic response of a chaotic reverberation chamber

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    This article presents a study of the electromagnetic response of a chaotic reverberation chamber (RC) in the presence of losses. By means of simulations and of experiments, the fluctuations in the maxima of the field obtained in a conventional mode-stirred RC are compared with those in a chaotic RC in the neighborhood of the Lowest Useable Frequency (LUF). The present work illustrates that the universal spectral and spatial statistical properties of chaotic RCs allow to meet more adequately the criteria required by the Standard IEC 61000-4-21 to perform tests of electromagnetic compatibility.Comment: 6 pages, 9 figure

    Microwave fidelity studies by varying antenna coupling

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    The fidelity decay in a microwave billiard is considered, where the coupling to an attached antenna is varied. The resulting quantity, coupling fidelity, is experimentally studied for three different terminators of the varied antenna: a hard wall reflection, an open wall reflection, and a 50 Ohm load, corresponding to a totally open channel. The model description in terms of an effective Hamiltonian with a complex coupling constant is given. Quantitative agreement is found with the theory obtained from a modified VWZ approach [Verbaarschot et al, Phys. Rep. 129, 367 (1985)].Comment: 9 pages 5 figur

    Numerical simulation of inductive heating processes

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    For product optimization regarding weight reduction, material properties have to be adapted efficiently. To achieve this, new compositions of materials can be created or the manufacturing process can be changed in a way that heterogeneous distributions of material properties are enabled. An example for such an improved process chain is the production of thermo-mechanically graded structures like shafts. The manufacturing method mainly consists of three stages. The first one is characterized by a local temperature increase of the workpiece due to inductive heating. In the second phase the workpiece is deformed and simultaneously cooled throughout the contact with the forming die. In the last step, however, a high pressured air stream is applied, leading to a partial cooling of the workpiece. The inductive heating step is controlled by an alternating current inducing a high frequency magnetic field, which causes a temperature increase due to the resulting eddy currents. To analyse this process, the coupling between the electric and the magnetic field is described by the fully coupled Maxwell equations. Moreover the heat conduction equation is considered to describe thermal effects. To solve this multifield the equations are in the first step decoupled using an additional time differentiation. In the second step an axisymmetric case is considered, motivated by the fact that the inductive heating process of a cylindrical shaft is analysed. Afterwards the resulting equations are spatially discretized by the Galerkin finite element method. The temporal discretization is carried out via the Newmark method so that afterwards the electrical source distribution can be achieved. As a consequence the temperature evolution is determined in a postprocessing step

    Getting a grip on your feelings: Effects of action orientation and external demands on intuitive affect regulation

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    The authors propose that volitional action is supported by intuitive affect regulation, defined as flexible, efficient, and nonrepressive control of own affective states. Intuitive affect regulation should be most apparent among action-oriented individuals under demanding conditions. Consistent with this, a demanding context led action-oriented individuals to down-regulate negative affect in self-reports (Study 1), in an affective Simon task (Study 2), and in a face discrimination task (Study 3). In line with the idea that intuitive affect regulation is guided by top-down self-regulation processes, intuitive affect regulation in a face discrimination task was mediated by increases in self-accessibility (Study 3). No parallel effects emerged among action-oriented participants in a nondemanding context or among state-oriented participants

    Effectiveness of Lasalocid with Solar-Dried Acid Treated and Ensiled Shelled Corn Finishing Rations

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    Three shelled corn storage forms (solar-dried, propionic acid-treated and ensiled) were also investigated in this trial because of the intensive interest in minimizing the energy costs required for drying or preserving high-moisture corn and to examine the relative feeding value of corn stored in these three ways. A horizontal plastic Silopress bag was used to store the ensiled shelled corn in order to gain experience with this ensiling systems

    Effectiveness of Cold-Flo Anhydrous Ammonia with Forage Sorghum Silage

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    Forage sorghum was treated with Cold-Flo anhydrous ammonia at ensiling time and compared with untreated silage supplemented with soybean meal at feeding time. One hundred Angus steers were used in the 91-day trial. Average daily gain of the cattle fed the two silages was very similar. However, cattle fed the amonia-treated forage sorghum consumed less feed than controls, resulting in a substantially better (16.7%) conversion by steers on the ammonia-treated silage ration. The result of this experiment indicate that Cold-Flo anhydrous ammonia is efficiently utilized as nonprotein nitrogen source with forage sorghum silage. Further research is necessary with other low energy silages to confirm this original finding and expand the beneficial uses of this inexpensive silage additive for producers
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