Energy Spectrum Evolution of a Diffuse Field in Elastic Body Caused by Weak Nonlinearity

We study the evolution of diffuse elastodynamic spectral energy density under the influence of weak nonlinearity. It is shown that the rate of change of this quantity is given by a convolution of the linear energy at two frequencies. Quantitative estimates are given for sample aluminum and fused silica blocks of experimental interest.Comment: 9 pages, 3 figures; revised for better presentatio

State variable feedback design of a control system for a coupled-core reactor

State variable feedback design of control system for coupled core nuclear reacto

Simulation study of a geometric shape factor technique for estimating earth-emitted radiant flux densities from wide-field-of-view radiation measurements

Geometric shape factors were computed and applied to satellite simulated irradiance measurements to estimate Earth emitted flux densities for global and zonal scales and for areas smaller than the detector field of view (FOV). Wide field of view flat plate detectors were emphasized, but spherical detectors were also studied. The radiation field was modeled after data from the Nimbus 2 and 3 satellites. At a satellite altitude of 600 km, zonal estimates were in error 1.0 to 1.2 percent and global estimates were in error less than 0.2 percent. Estimates with unrestricted field of view (UFOV) detectors were about the same for Lambertian and limb darkening radiation models. The opposite was found for restricted field of view detectors. The UFOV detectors are found to be poor estimators of flux density from the total FOV and are shown to be much better as estimators of flux density from a circle centered at the FOV with an area significantly smaller than that for the total FOV

The design of linear multivariable control systems using modern control theory /with applications to coupled core reactor control/

Linear multivariable control system design using modern control theory, and application to coupled core reactor contro

Pilot study and evaluation of a SMMR-derived sea ice data base

Data derived from the Nimbus 7 scanning multichannel microwave radiometer (SMMR) are discussed and the types of problems users have with satellite data are documented. The development of software for assessing the SMMR data is mentioned. Two case studies were conducted to verify the SMMR-derived sea ice concentrations and multi-year ice fractions. The results of a survey of potential users of SMMR data are presented, along with SMMR-derived sea ice concentration and multiyear ice fraction maps. The interaction of the Arctic atmosphere with the ice was studied using the Nimbus 7 SMMR. In addition, the characteristics of ice in the Arctic ocean were determined from SMMR data

Scattering fidelity in elastodynamics

The recent introduction of the concept of scattering fidelity, causes us to revisit the experiment by Lobkis and Weaver [Phys. Rev. Lett. 90, 254302 (2003)]. There, the ``distortion'' of the coda of an acoustic signal is measured under temperature changes. This quantity is in fact the negative logarithm of scattering fidelity. We re-analyse their experimental data for two samples, and we find good agreement with random matrix predictions for the standard fidelity. Usually, one may expect such an agreement for chaotic systems only. While the first sample, may indeed be assumed chaotic, for the second sample, a perfect cuboid, such an agreement is more surprising. For the first sample, the random matrix analysis yields a perturbation strength compatible with semiclassical predictions. For the cuboid the measured perturbation strength is much larger than expected, but with the fitted values for this strength, the experimental data are well reproduced.Comment: 4 page

Effect of growth regulators and heat on germination of Tokay grape seeds

Immersing seeds of 'Tokay' for 24 hours in water ranging from 27 ° to 54 °C failed to terminate rest. KGA3 terminated rest in 50% of the seeds, ancl morphactin at 100 ppm and ethephon at 5,000 ppm resulted in some enhancement of germination. However, SADH, CCC, and ABA treatments were not effective. KGA3 at 1 ppm caused 33% germination of scarified resting seeds. SADH increased the germination rate of nonresting seeds, but ABA, BOA, CCC, ethyl alcohol, and sulphuric acid clecreased the rate.Der Einfluß von Wachstumsregulatoren und Wärmebehandlung auf die Keimungvon Samen der Rebsorte TokaySamen der Rebsorte „Tokay", die 24 Stunden in Wasser mit Temperaturen von 27 ° bis 54 °C getaucht worden waren, beendeten die Dormanz nicht. KGA3 hob die Dormanz bei 50% der Samen auf, während Behandlung mit 100 ppm Morphaktin oder mit 5000 ppm Ethephon die Keimung erhöhten. Die Anwendung von SADH, CCC und ABA war jedoch wirkungslos. 1 ppm KGA3 verursachte bei angeritzten dormanten Samen eine Keimung von 33%. SADH steigerte die Keimungsrate der nichtruhenden Samen, während ABA, BOA, CCC, Äthylalkohol und Schwefelsäure die Keimungsrate herabsetzten

Quasi Two-dimensional Transfer of Elastic Waves

A theory for multiple scattering of elastic waves is presented in a random medium bounded by two ideal free surfaces, whose horizontal size is infinite and whose transverse size is smaller than the mean free path of the waves. This geometry is relevant for seismic wave propagation in the Earth crust. We derive a time-dependent, quasi-2D radiative transfer equation, that describes the coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and Lamb waves). Expressions are found that relate the small-scale fluctuations to the life time of the modes and to their coupling rates. We discuss a diffusion approximation that simplifies the mathematics of this model significantly, and which should apply at large lapse times. Finally, coherent backscattering is studied within the quasi-2D radiative transfer equation for different source and detection configurations.Comment: REVTeX, 36 pages with 10 figures. Submitted to Phys. Rev.

Bacterial Methane Oxidation and its Influence in the Aquatic Environment

This study was supported in part by the Office of Water Resources Research, U.S. Department of the Interior under Project A-027-OHIO.(print) vii, 133 p. : ill. ; 29 cm.Table of Contents -- List of Tables -- List of Figures -- 1. Introduction -- 2. Review of the Literature -- 3. Mixed Culture Growth Studies -- 4. Pure Culture Growth Studies -- 5. Morphology of Methane Oxidizing Bacteria -- 6. Isolation of Intracytoplasmic Membranes -- 7. Lipids of Cells and Membranes -- 8. Proteins of Cells and Membranes -- 9. Summary -- 10. Conclusions and Recommendation

Role of oxygen in the electron-doped superconducting cuprates

We report on resistivity and Hall measurements in thin films of the electron-doped superconducting cuprate Pr$_{2-x}$Ce$_{x}$CuO$_{4\pm\delta}$. Comparisons between x = 0.17 samples subjected to either ion-irradiation or oxygenation demonstrate that changing the oxygen content has two separable effects: 1) a doping effect similar to that of cerium, and 2) a disorder effect. These results are consistent with prior speculations that apical oxygen removal is necessary to achieve superconductivity in this compound.Comment: 5 pages, 5 figure