Superconductivity in an anisotropic three-dimensional narrow-band system

1991 ◽  
Vol 43 (7) ◽  
pp. 5606-5611 ◽  
Author(s):  
D. K. Ray ◽  
J. Konior ◽  
A. M. Oleś ◽  
A. N. Das
Keyword(s):  
Narrow Band ◽  
Band System ◽  
Three Dimensional

Heterodyne Digital Control of a High-Frequency Micromechanical Oscillator

2005 ◽  
Vol 128 (3) ◽  
pp. 577-583 ◽  
Author(s):  
Thomas E. Kriewall ◽  
Joseph L. Garbini ◽  
John A. Sidles ◽  
Jonathan P. Jacky
Keyword(s):  
High Frequency ◽  
Digital Control ◽  
Narrow Band ◽  
Band System ◽  
Digital Signal ◽  
Computational Effort ◽  
Pass Band ◽  
Magnetic Resonance Force Microscopy ◽  
Force Microscopy ◽  
Lock In

In this paper we present heterodyne control as a technique for digital feedback control of a high-frequency, narrowband micromechanical oscillator. In this technique, isolated and synchronized hardware downconversion and upconversion components are used in conjunction with digital signal processing (DSP) to control the oscillator. Heterodyne control offers reduced computational effort for the digital control of high-frequency, narrow band system, the reduction of noise outside the pass-band, and the generation of lock-in amplifier signals. We present heterodyne control with design criteria in the context of magnetic resonance force microscopy (MRFM) cantilever control. Finally, we present experimental results of heterodyne control applied to an emulated radio-frequency microcantilever system.

PATTERN SELECTION IN BÉNARD-MARANGONI CONVECTION

1994 ◽  
Vol 04 (05) ◽  
pp. 1085-1094 ◽  
Author(s):  
MICHAEL BESTEHORN
Keyword(s):  
Numerical Scheme ◽  
Marangoni Convection ◽  
Narrow Band ◽  
Three Dimensional ◽  
Marangoni Effect ◽  
Hydrodynamic Equations ◽  
Instability Mechanism ◽  
Amplitude Equations ◽  
Random Patterns ◽  
Phase Instabilities

Pattern formation in fluids with a free flat upper surface is examined. On that surface, the Marangoni effect provides an additional instability mechanism. Based on amplitude equations it is shown that phase instabilities confine the region of stable hexagons to a narrow band of wavelengths. On the other hand we developed a numerical scheme that allows for a direct integration of the fully three-dimensional hydrodynamic equations. There we show the evolution of random patterns and the creation and stabilization of defects as well as the instability of hexagonal patterns lying outside the stable band of wave vectors.

scholarly journals Promoting a More Interactive Public Archaeology

2015 ◽  
Vol 3 (3) ◽  
pp. 235-248 ◽  
Author(s):  
Bernard K. Means
Keyword(s):  
Narrow Band ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Public Archaeology ◽  
Archaeological Sites ◽  
Digital Models ◽  
The Past ◽  
Fresh Perspective ◽  
Virginia Commonwealth University ◽  
3D Digital Models

AbstractStewards of the tangible past are increasingly embracing technologies that enable digital preservation of rare and fragile finds. The Virtual Curation Laboratory (VCL) at Virginia Commonwealth University (VCU) partners with museums, cultural heritage locations, and collections repositories to create three-dimensional (3D) digital models of artifacts from archaeological sites distributed across the globe. In the VCL, undergraduate VCU students bring a fresh perspective unburdened by archaeological orthodoxy as they use a laser scanner to record artifact details, edit the resulting digital models, and print plastic replicas that are painted to resemble the original items. The 3D digital models and printed replicas allow for new ways of visualizing the past, while preserving the actual artifacts themselves. These forms of archaeological visualization enable the broader public and not just a narrow band of researchers to dynamically and meaningfully interact with rare and fragile objects in ways that would otherwise not be possible, empowering their own contributions to interpreting, understanding, and reimagining the past. We must embrace co-creation through virtual artifact curation and recognize that, while we sacrifice some control over the stories that are told about the past, more stories will be told and shared as pieces of the past become more accessible.

Burial and Scour of Short Cylinders and Truncated Cones Due to Long-Crested and Short-Crested Nonlinear Random Waves Plus Currents

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Muk Chen Ong ◽  
Dag Myrhaug
Keyword(s):  
Narrow Band ◽  
Three Dimensional ◽  
Wave Crest ◽  
Height Distribution ◽  
Random Waves ◽  
Regular Waves ◽  
Nonlinear Random Waves ◽  
2D And 3D ◽  
The Waves ◽  
Crest Height

This paper provides a practical stochastic method by which the burial and scour depths of short cylinders and truncated cones exposed to long-crested (two-dimensional (2D)) and short-crested (three-dimensional (3D)) nonlinear random waves plus currents can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Forristall second-order wave crest height distribution representing both 2D and 3D nonlinear random waves. Moreover, the formulas for the burial and the scour depths for regular waves plus currents presented by previous published work for short cylinders and truncated cones are used.

Photometric separation of temperature, reddening, and chemical composition

1966 ◽  
Vol 24 ◽  
pp. 211-219
Author(s):  
J. A. Williams
Keyword(s):  
Chemical Composition ◽  
Narrow Band ◽  
Band System ◽  
Effects Of Temperature ◽  
K Giants

It is very difficult to separate the effects of interstellar reddening from the effects of temperature reddening and differences in chemical composition. In this paper I discuss several methods which have been used to make this separation. The application of the narrow-band system of Crawford (1), Table 1, to population I cepheids with periods greater than 13 days and the evidence from G–K giants that the system makes the separation are described in more detail.

Experiments on nonlinear gravity–capillary waves

1999 ◽  
Vol 380 ◽  
pp. 205-232 ◽  
Author(s):  
LEV SHEMER ◽  
MELAD CHAMESSE
Keyword(s):  
Narrow Band ◽  
Numerical Study ◽  
Three Dimensional ◽  
Capillary Waves ◽  
Carrier Wave ◽  
Nls Equation ◽  
Zakharov Equation ◽  
The Stability ◽  
Nonlinear Gravity

Benjamin–Feir instability of nonlinear gravity–capillary waves is studied experimentally. The experimental results are compared with computations performed for values of wavelength and steepness identical to those employed in the experiments. The theoretical approach is based on the Zakharov nonlinear equation which is modified here to incorporate weak viscous dissipation. Experiments are performed in a wave ume which has an accurately controlled wavemaker for generation of the carrier wave, as well as an additional independent conical wavemaker for generation of controlled three-dimensional disturbances. The approach adopted in the present experimental investigation allows therefore the determination of the actual boundaries of the instability domain, and not just the most unstable disturbances. Instantaneous surface elevation measurements are performed with capacitance-type wave gauges. Multipoint measurements make it possible to determine the angular dependence of the amplitude of the forced and unforced disturbances, as well as their variation along the tank. The limits of the instability domains obtained experimentally for each set of carrier wave parameters agree favourably with those computed numerically using the model equation. The numerical study shows that application of the Zakharov equation, which is free of the narrow-band approximation adopted in the derivation of the nonlinear Schrödinger (NLS) equation, may lead to qualitatively different results regarding the stability of nonlinear gravity–capillary waves. The present experiments support the results of the numerical investigation.

Prediction of Radiative Heat Transfer in Industrial Equipment Using the Radiation Element Method

2001 ◽  
Vol 123 (4) ◽  
pp. 530-536 ◽  
Author(s):  
Zhixiong Guo ◽  
Shigenao Maruyama
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Narrow Band ◽  
Particle Density ◽  
Three Dimensional ◽  
Wide Band ◽  
Band Model ◽  
Participating Media ◽  
Carbon Particles

The radiation element method by ray emission method, REM2, has been formulated to predict radiative heat transfer in three-dimensional arbitrary participating media with nongray and anisotropically scattering properties surrounded by opaque surfaces. To validate the method, benchmark comparisons were conducted against the existing several radiation methods in a rectangular three-dimensional media composed of a gas mixture of carbon dioxide and nitrogen and suspended carbon particles. Good agreements between the present method and the Monte Carlo method were found with several particle density variations, in which participating media of optical thin, medium, and thick were included. As a numerical example, the present method is applied to predict radiative heat transfer in a boiler model with nonisothermal combustion gas and carbon particles and diffuse surface wall. Elsasser narrow-band model as well as exponential wide-band model is adopted to consider the spectral character of CO2 and H2O gases. The distributions of heat flux and heat flux divergence in the boiler furnace are obtained. The difference of results between narrow-band and wide-band models is discussed. The effects of gas model, particle density, and anisotropic scattering are scrutinized.

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