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Light, sound, and waves science fair projects : revised and expanded using the scientific method
\"Explains how to use the scientific method to conduct several science experiments about light, sound, and waves. Includes ideas for science fair projects\"--Provided by publisher.
Book
The Influence of Characteristic Sea State Parameters on the Accuracy of Irregular Wave Field Simulations of Different Complexity
The accurate description of the complex genesis and evolution of ocean waves, as well as the associated kinematics and dynamics is indispensable for the design of offshore structures and the assessment of marine operations. In the majority of cases, the water-wave problem is reduced to potential flow theory on a somehow simplified level. However, the nonlinear terms in the surface boundary conditions and the fact that they must be fulfilled on the unknown water surface make the boundary value problem considerably complex. Hereby, the contrary objectives with respect to a very accurate representation of reality and numerical efficiency must be balanced wisely. This paper investigates the influence of characteristic sea state parameters on the accuracy of irregular wave field simulations of different complexity. For this purpose, the high-order spectral method was applied and the underlying Taylor series expansion was truncated at different orders so that numerical simulations of different complexity can be investigated. It is shown that, for specific characteristic sea state parameters, the boundary value problem can be significantly reduced while providing sufficient accuracy.
Journal Article
Gravity Wave Activity During the 2024 Sudden Stratospheric Warmings Observed by Atmospheric Waves Experiment (AWE)
The National Aeronautics and Space Administration (NASA) Atmospheric Waves Experiment (AWE) instrument, launched in November 2023, provides direct observation of small‐scale (30–300 km) gravity waves (GWs) in the mesosphere on a global scale. This work examined changes in GW activity observed by AWE during two major Sudden Stratospheric Warmings (SSWs) in the 2023 and 2024 winter season. Northern Hemisphere (NH) midlatitude GW activity during these events shared similarities. Variations in mesospheric GW activity showed an evident correlation with the magnitude of zonal wind in the upper stratosphere. NH midlatitude GW activity at ∼ $\\mathit{\\sim }$87 km was reduced following the onset of SSWs, likely caused by wind filtering and wave saturation. The upward propagation of GWs was suppressed when the zonal wind reversed from eastward to westward in the upper stratosphere. In regions where the zonal wind weakened but remained eastward, the weakened GWs could be due to their refraction to shorter vertical wavelengths.
Journal Article
Investigating sound
Explains the properties of sound with experiments and investigations that explore how the energy form is affected by material density, pitch, and distance.
Book
First observations of X-mode suppression of O-mode HF enhancements at 6300 Å
We present observations of radio induced optical emissions from a HAARP experiment with simultaneous transmission in X and O‐mode. The additional transmission of X‐mode with a frequency 700 kHz higher than the O‐mode, reduces the enhancement of the 6300 Å emission. This suggests that the wave‐plasma process that energizes the electrons, which excites oxygen to the O(1D) state, is closely connected to the excitation of upper‐hybrid waves, whose onset and initial growth are reduced by additional X‐mode pumping.
Journal Article
Explore light and optics!
Imagine a world without light. What would it be like? Dark, cold, and lifeless! In this book, readers find out why light is so important to our world.
Book
High Frequency Analyzer (HFA) of Plasma Wave Experiment (PWE) onboard the Arase spacecraft
The High Frequency Analyzer (HFA) is a subsystem of the Plasma Wave Experiment onboard the Arase (ERG) spacecraft. The main purposes of the HFA include (1) determining the electron number density around the spacecraft from observations of upper hybrid resonance (UHR) waves, (2) measuring the electromagnetic field component of whistler-mode chorus in a frequency range above 20 kHz, and (3) observing radio and plasma waves excited in the storm-time magnetosphere. Two components of AC electric fields detected by Wire Probe Antenna and one component of AC magnetic fields detected by Magnetic Search Coils are fed to the HFA. By applying analog and digital signal processing in the HFA, the spectrograms of two electric fields (EE mode) or one electric field and one magnetic field (EB mode) in a frequency range from 10 kHz to 10 MHz are obtained at an interval of 8 s. For the observation of plasmapause, the HFA can also be operated in PP (plasmapause) mode, in which spectrograms of one electric field component below 1 MHz are obtained at an interval of 1 s. In the initial HFA operations from January to July, 2017, the following results are obtained: (1) UHR waves, auroral kilometric radiation (AKR), whistler-mode chorus, electrostatic electron cyclotron harmonic waves, and nonthermal terrestrial continuum radiation were observed by the HFA in geomagnetically quiet and disturbed conditions. (2) In the test operations of the polarization observations on June 10, 2017, the fundamental R-X and L-O mode AKR and the second-harmonic R-X mode AKR from different sources in the northern polar region were observed. (3) The semiautomatic UHR frequency identification by the computer and a human operator was applied to the HFA spectrograms. In the identification by the computer, we used an algorithm for narrowing down the candidates of UHR frequency by checking intensity and bandwidth. Then, the identified UHR frequency by the computer was checked and corrected if needed by the human operator. Electron number density derived from the determined UHR frequency will be useful for the investigation of the storm-time evolution of the plasmasphere and topside ionosphere.
Journal Article
Superfluid optomechanics: coupling of a superfluid to a superconducting condensate
We investigate the low loss acoustic motion of superfluid 4He parametrically coupled to a very low loss, superconducting Nb microwave resonator, forming a gram-scale, sideband resolved, optomechanical system. We demonstrate the detection of a series of acoustic modes with quality factors as high as . At higher temperatures, the lowest dissipation modes are limited by an intrinsic three phonon process. Acoustic quality factors approaching 1011 may be possible in isotopically purified samples at temperatures below 10 mK. A system of this type may be utilized to study macroscopic quantized motion and as a freqency tunable, ultra-sensitive sensor of extremely weak displacements and forces, such as continuous gravity wave sources.
Journal Article
Design of Portable Reefs to Protect Young Mangroves
For a successful mangrove plantation, previous studies have proposed a small rubble mound breakwater, termed a “portable reef”, and explored the effectiveness of such reefs in terms of wave transmission. This study conducted a real-scale wave flume experiment incorporating a portable reef to assess the oscillatory behavior of young mangroves. To capture the dynamics of these young mangrove analogs—represented as elastic bodies—we employed a high-speed camera for precise tracking. A comparative analysis of the oscillatory characteristics was performed, evaluating the responses in both the presence and absence of the reef. The findings revealed several important points. First, portable reefs can effectively reduce wave heights, but they reduce plant oscillations to an even greater degree. Second, by calibrating the elastic modulus of the plant models, their oscillation behaviors can be analytically predicted. The results of our analytical model indicate that the acceleration experienced by the plants is amplified under conditions of shorter wave periods and softer stems, highlighting an increased susceptibility to damage from short-period waves, particularly in very young mangroves. Third, we identified that the conventional wave transmission formulas tend to overestimate the reduction in wave energy attributable to portable reefs, which consequently leads to an underestimation of the young mangroves’ oscillations. Based on these findings, we propose an integrated chart that combines wave transmission and plant oscillation coefficients, aimed at enhancing the design and effectiveness of portable reefs in protecting young mangroves. The insights obtained from this study will aid in the informed design of portable reefs.
Journal Article