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Full-Text Articles in Physical Sciences and Mathematics

Large‐Amplitude Mountain Waves In The Mesosphere Observed On 21 June 2014 During Deepwave: 2. Nonlinear Dynamics, Wave Breaking, And Instabilities, David C. Fritts, Ling Wang, Michael J. Taylor, Pierre-Dominique Pautet, Neal R. Criddle, Bernd Kaifler, Stephen D. Eckermann, Ben Liley Aug 2019

Large‐Amplitude Mountain Waves In The Mesosphere Observed On 21 June 2014 During Deepwave: 2. Nonlinear Dynamics, Wave Breaking, And Instabilities, David C. Fritts, Ling Wang, Michael J. Taylor, Pierre-Dominique Pautet, Neal R. Criddle, Bernd Kaifler, Stephen D. Eckermann, Ben Liley

Publications

Weak cross‐mountain flow over the New Zealand South Island on 21 June 2014 during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) led to large‐amplitude mountain waves in the mesosphere and lower thermosphere. The mesosphere and lower thermosphere responses were observed by ground‐based instruments in the lee of the Southern Alps supporting DEEPWAVE, including an Advanced Mesosphere Temperature Mapper, a Rayleigh lidar, an All‐Sky Imager, and a Fabry‐Perot Interferometer. The character of the mountain wave responses at horizontal scales of ~30–90 km reveals strong “sawtooth” variations in the temperature field suggesting large vertical and horizontal ...


Thermal Structure Of The Mesopause Region During The Wadis-2 Rocket Campaign, Raimund Wörl, Boris Strelnikov, Timo P. Viehl, Josef Höffner, Pierre-Dominique Pautet, Michael J. Taylor, Yucheng Zhao, Franz-Josef Lübken Jan 2019

Thermal Structure Of The Mesopause Region During The Wadis-2 Rocket Campaign, Raimund Wörl, Boris Strelnikov, Timo P. Viehl, Josef Höffner, Pierre-Dominique Pautet, Michael J. Taylor, Yucheng Zhao, Franz-Josef Lübken

Publications

This paper presents simultaneous temperature measurements by three independent instruments during the WADIS-2 rocket campaign in northern Norway (69 N, 14 E) on 5 March 2015. Vertical profiles were measured in situ with the CONE instrument. Continuous mobile IAP Fe lidar (Fe lidar) measurements during a period of 24 h, as well as horizontally resolved temperature maps by the Utah State University (USU) Advanced Mesospheric Temperature Mapper (AMTM) in the mesopause region, are analysed. Vertical and horizontal temperature profiles by all three instruments are in good agreement. A harmonic analysis of the Fe lidar measurements shows the presence of waves ...


Spacetime Groups, Ian M. Anderson, Charles G. Torre Jan 2019

Spacetime Groups, Ian M. Anderson, Charles G. Torre

Publications

A spacetime group is a connected 4-dimensional Lie group G endowed with a left invariant Lorentz metric h and such that the connected component of the isometry group of h is G itself. The Newman-Penrose formalism is used to give an algebraic classification of spacetime groups, that is, we determine a complete list of inequivalent spacetime Lie algebras, which are pairs (g,η), with g being a 4-dimensional Lie algebra and η being a Lorentzian inner product on g. A full analysis of the equivalence problem for spacetime Lie algebras is given which leads to a completely algorithmic solution to ...


Seasonal Propagation Characteristics Of Mstids Observed At High Latitudes Over Central Alaska Using The Poker Flat Incoherent Scatter Radar, Michael R. Negale, Michael J. Taylor, M. J. Nicolls, Sharon L. Vadas, Kim Nielsen, Craig J. Heinselman May 2018

Seasonal Propagation Characteristics Of Mstids Observed At High Latitudes Over Central Alaska Using The Poker Flat Incoherent Scatter Radar, Michael R. Negale, Michael J. Taylor, M. J. Nicolls, Sharon L. Vadas, Kim Nielsen, Craig J. Heinselman

Publications

Near‐continuous electron density measurements obtained over a ∼3 year period, 2010–2013, using the Poker Flat Incoherent Scatter Radar (PFISR) in central Alaska (69°N, 147°W) have been analyzed to quantify the properties of over 650 high‐latitude medium‐scale traveling ionospheric disturbances (MSTIDs). Our analysis focused on the altitude range 100–300 km encompassing the lower ionosphere/thermosphere and yielded first full seasonal day/night distributions of MSTIDs at high northern latitudes with mean values: horizontal wavelength 446 km, horizontal phase speed 187 m/s, and period 41 min. These year‐round measurements fill an important summertime ...


An Asymptotic Analysis For Generation Of Unsteady Surface Waves On Deep Water By Turbulence, Shahrdad Sajjadi Mar 2018

An Asymptotic Analysis For Generation Of Unsteady Surface Waves On Deep Water By Turbulence, Shahrdad Sajjadi

Publications

The detailed mathematical study of the recent paper by Sajjadi, Hunt and Drullion (2014) is presented. The mathematical developement considered by them, for unsteady growing monochromatic waves is also extended to Stokes waves. The present contribution also demonstrates agreement with the pioneering work of Belcher and Hunt (1993) which is valid in the limit of the complex part of the wave phase speed ci ↓ 0. It is further shown that the energy-transfer parameter and the surface shear stress for a Stokes wave reverts to a monochromatic wave when the second harmonic is excluded. Furthermore, the present theory can be ...


Unexpected Occurrence Of Mesospheric Frontal Gravity Wave Events Over South Pole (90°S), Pierre-Dominique Pautet, Michael J. Taylor, J. B. Snively, Christina Solorio Jan 2018

Unexpected Occurrence Of Mesospheric Frontal Gravity Wave Events Over South Pole (90°S), Pierre-Dominique Pautet, Michael J. Taylor, J. B. Snively, Christina Solorio

Publications

Since 2010, Utah State University has operated an infrared Advanced Mesospheric Temperature Mapper at the Amundsen–Scott South Pole station to investigate the upper atmosphere dynamics and temperature deep within the vortex. A surprising number of “frontal” gravity wave events (86) were recorded in the mesospheric OH(3,1) band intensity and rotational temperature images (typical altitude of ~87 km) during four austral winters (2012–2015). These events are gravity waves (GWs) characterized by a sharp leading wave front followed by a quasi-monochromatic wave train that grows with time. A particular subset of frontal gravity wave events has been identified ...


Investigating Gravity Waves In Polar Mesospheric Clouds Using Tomographic Reconstructions Of Aim Satellite Imagery, V. P. Hart, M. J. Taylor, T. E. Doyle, Yucheng Zhao, Pierre-Dominique Pautet, B. L. Carruth, D. W. Rusch, J. M. Russell Iii Jan 2018

Investigating Gravity Waves In Polar Mesospheric Clouds Using Tomographic Reconstructions Of Aim Satellite Imagery, V. P. Hart, M. J. Taylor, T. E. Doyle, Yucheng Zhao, Pierre-Dominique Pautet, B. L. Carruth, D. W. Rusch, J. M. Russell Iii

Publications

This research presents the first application of tomographic techniques for investigating gravity wave structures in polar mesospheric clouds (PMCs) imaged by the Cloud Imaging and Particle Size instrument on the NASA AIM satellite. Albedo data comprising consecutive PMC scenes were used to tomographically reconstruct a 3‐D layer using the Partially Constrained Algebraic Reconstruction Technique algorithm and a previously developed “fanning” technique. For this pilot study, a large region (760 × 148 km) of the PMC layer (altitude ~83 km) was sampled with a ~2 km horizontal resolution, and an intensity weighted centroid technique was developed to create novel 2‐D ...


A Comparison Of Online, Video Synchronous, And Traditional Learning Modes For An Introductory Undergraduate Physics Course, Emily K. Faulconer, John C. Griffith, Beverly Wood, Donna Roberts Jan 2018

A Comparison Of Online, Video Synchronous, And Traditional Learning Modes For An Introductory Undergraduate Physics Course, Emily K. Faulconer, John C. Griffith, Beverly Wood, Donna Roberts

Publications

While the equivalence between online and traditional classrooms has been well-researched, very little of this includes college-level introductory Physics. Only one study explored Physics at the whole-class level rather than specific course components such as a single lab or a homework platform. In this work, we compared the failure rate, grade distribution, and withdrawal rates in an introductory undergraduate Physics course across several learning modes including traditional face-to-face instruction, synchronous video instruction, and online classes. Statistically significant differences were found for student failure rates,grade distribution, and withdrawal rates but yielded small effect sizes. Post-hoc pair-wise test was run to ...


Low Frequency Electromagnetic Radiation From Gravitational Waves Generated By Neutron Stars, Preston Jones, Andri Gretarsson, Douglas Singleton Dec 2017

Low Frequency Electromagnetic Radiation From Gravitational Waves Generated By Neutron Stars, Preston Jones, Andri Gretarsson, Douglas Singleton

Publications

We investigate the possibility of observing very low frequency (VLF) electromagnetic radiation produced from the vacuum by gravitational waves. We review the calculations leading to the possibility of vacuum conversion of gravitational waves into electromagnetic waves and show how this process evades the well-known prohibition against particle production from gravitational waves. Using Newman-Penrose scalars, we estimate the luminosity of this proposed electromagnetic counterpart radiation coming from gravitational waves produced by neutron star oscillations. The detection of electromagnetic counterpart radiation would provide an indirect way of observing gravitational radiation with future spacecraft missions, especially lunar orbiting probes.


Localization Of Interacting Fields In Five-Dimensional Braneworld Models, Dewi Wulandari, Triyanta, Jusak S. Kosasih, Douglas Singleton, Preston Jones Nov 2017

Localization Of Interacting Fields In Five-Dimensional Braneworld Models, Dewi Wulandari, Triyanta, Jusak S. Kosasih, Douglas Singleton, Preston Jones

Publications

We study localization properties of fundamental fields which are coupled to one another through the gauge mechanism both in the original Randall-Sundrum (RS) and in the modified Randall-Sundrum (MRS) braneworld models: scalar-vector, vector-vector, and spinor-vector configuration systems. For this purpose we derive conditions of localization, namely the finiteness of integrals over the extra coordinate in the action of the system considered. We also derive field equations for each of the systems and then obtain their solutions corresponding to the extra dimension by a separation of variable method for every field involved in each system. We then insert the obtained solutions ...


Velocity-Dependent Inverse Cubic Force And Solar System Gravity Tests, Quentin G. Bailey, Daniel Havert Sep 2017

Velocity-Dependent Inverse Cubic Force And Solar System Gravity Tests, Quentin G. Bailey, Daniel Havert

Publications

Higher mass dimension terms in an effective field theory framework for tests of spacetime symmetries are studied. Using a post-Newtonian expansion method, we derive the spacetime metric and the equations of motion for a binary system. This reveals an effective inverse cubic force correction to post-Newtonian general relativity that depends on the velocity of the bodies in the system. The results are studied in the context of laboratory and space-based tests including the effects on solar-system ephemeris, laser ranging observations, and gravimeter tests. This work reveals the coefficient combinations for mass dimension 5 operators controlling CPT violation for gravity that ...


Variations In Biocorona Formation Related To Defects In The Structure Of Single Walled Carbon Nanotubes And The Hyperlipidemic Disease State, Achyut J. Raghavendra, Kristofer Fritz, Sherleen Fu, Jared M. Brown, Ramakrishna Podila, Jonathan H. Shannahan Aug 2017

Variations In Biocorona Formation Related To Defects In The Structure Of Single Walled Carbon Nanotubes And The Hyperlipidemic Disease State, Achyut J. Raghavendra, Kristofer Fritz, Sherleen Fu, Jared M. Brown, Ramakrishna Podila, Jonathan H. Shannahan

Publications

Ball-milling utilizes mechanical stress to modify properties of carbon nanotubes (CNTs) including size, capping, and functionalization. Ball-milling, however, may introduce structural defects resulting in altered CNT-biomolecule interactions. Nanomaterial-biomolecule interactions result in the formation of the biocorona (BC), which alters nanomaterial properties, function, and biological responses. The formation of the BC is governed by the nanomaterial physicochemical properties and the physiological environment. Underlying disease states such as cardiovascular disease can alter the biological milieu possibly leading to unique BC identities. In this ex vivo study, we evaluated variations in the formation of the BC on single-walled CNTs (SWCNTs) due to physicochemical ...


Cirrus Cloud Microphysics Over Darwin, Australia, Dorothea Ivanova, Matthew Johnson Apr 2017

Cirrus Cloud Microphysics Over Darwin, Australia, Dorothea Ivanova, Matthew Johnson

Publications

Ice clouds, crucial to the understanding of both short - and long - term climate trends, are poorly represented in global climate models (GCMs). Cirrus clouds, one of the largest uncertainties in the global radiation budget, have been inadequately studied at low latitudes. Parameterizations exist for mid - latitude and tropical cirrus ( Ivanova et al. 2001; McFarquhar et al. 1997). Due to climate sensitivity in the GCM with respect to cloud input, without robust parameterizations of cirrus clouds, the GCM is inaccurate over most output fields, including radiative forcing, temperature, albedo, and heat flux (Yao and Del Genio 1999).

Studies of the microphysical ...


Lorentz-Symmetry Test At Planck-Scale Suppression With Nucleons In A Spin-Polarized 133 Cs Cold Atom Clock, H. Pihan-Le Bars, C. Guerlin, R.-D. Lasseri, J.-P. Ebran, Q. G. Bailey, S. Bize, E. Khan, P. Wolf Apr 2017

Lorentz-Symmetry Test At Planck-Scale Suppression With Nucleons In A Spin-Polarized 133 Cs Cold Atom Clock, H. Pihan-Le Bars, C. Guerlin, R.-D. Lasseri, J.-P. Ebran, Q. G. Bailey, S. Bize, E. Khan, P. Wolf

Publications

The authors introduce an improved model that links the frequency of the 133 Cs hyperfine Zeeman transitions.


Particle Production In A Gravitational Wave Background, Preston Jones, Patrick Mcdougall, Douglas Singleton Mar 2017

Particle Production In A Gravitational Wave Background, Preston Jones, Patrick Mcdougall, Douglas Singleton

Publications

In this article, the authors study the possibility that massless particles, such as photons, are produced by a gravitational wave. That such a process should occur is implied by tree-level Feynman diagrams such as two gravitons turning into two photons, i.e., g + g → γ + γ. Here we calculate the rate at which a gravitational wave creates a massless scalar field. This is done by placing the scalar field in the background of a plane gravitational wave and calculating the 4-current of the scalar field. Even in the vacuum limit of the scalar field it has a nonzero vacuum expectation ...


Contribution Of Engineered Nanomaterials Physicochemical Properties To Mast Cell Degranulation, Monica M. Johnson, Ryan Mendoza, Achyut J. Raghavendra, Ramakrishna Podila, Jared M. Brown Mar 2017

Contribution Of Engineered Nanomaterials Physicochemical Properties To Mast Cell Degranulation, Monica M. Johnson, Ryan Mendoza, Achyut J. Raghavendra, Ramakrishna Podila, Jared M. Brown

Publications

The rapid development of engineered nanomaterials (ENMs) has grown dramatically in the last decade, with increased use in consumer products, industrial materials, and nanomedicines. However, due to increased manufacturing, there is concern that human and environmental exposures may lead to adverse immune outcomes. Mast cells, central to the innate immune response, are one of the earliest sensors of environmental insult and have been shown to play a role in ENM-mediated immune responses. Our laboratory previously determined that mast cells are activated via a non-FcεRI mediated response following silver nanoparticle (Ag NP) exposure, which was dependent upon key physicochemical properties. Using ...


Charge-Transfer Interactions Induce Surface Dependent Conformational Changes In Apolipoprotein Biocorona, Achyut J. Raghavendra, Nasser Alsaleh, Jared M. Brown, Ramakrishna Podila Mar 2017

Charge-Transfer Interactions Induce Surface Dependent Conformational Changes In Apolipoprotein Biocorona, Achyut J. Raghavendra, Nasser Alsaleh, Jared M. Brown, Ramakrishna Podila

Publications

Upon introduction into a biological system, engineered nanomaterials (ENMs) rapidly associate with a variety of biomolecules such as proteins and lipids to form a biocorona. The presence of “biocorona” influences nano–bio interactions considerably, and could ultimately result in altered biological responses. Apolipoprotein A-I (ApoA-I), the major constituent of high-density lipoprotein (HDL), is one of the most prevalent proteins found in ENM-biocorona irrespective of ENM nature, size, and shape. Given the importance of ApoA-I in HDL and cholesterol transport, it is necessary to understand the mechanisms of ApoA-I adsorption and the associated structural changes for assessing consequences of ENM exposure ...


Index Of Refraction From The Near-Ultraviolet To The Near-Infrared From A Single Crystal Microwave-Assisted Cvd Diamond, Giorgio Turri, Scott Webster, Ying Chen, Benjamin Wickham, Andrew Bennett, Michael Bass Mar 2017

Index Of Refraction From The Near-Ultraviolet To The Near-Infrared From A Single Crystal Microwave-Assisted Cvd Diamond, Giorgio Turri, Scott Webster, Ying Chen, Benjamin Wickham, Andrew Bennett, Michael Bass

Publications

The refractive index of a type IIa CVD-grown single-crystal diamond was measured by ellipsometry from the near ultraviolet to the near infrared region of the spectrum. As a consequence, a one term Sellmeier Equation with coefficents of B-1 = 4.658 and C-1 = 112.5 for the refractive index of diamond, for the wavelength range from 300 to 1650 nm, was derived that is only as accurate as the input data, +/- 0.002. The experimental results in this paper between 800 and 1650 nm are new, adding to the values available in the literature.


Wave Motion Induced By Turbulent Shear Flows Over Growing Stokes Waves, Shahrdad Sajjadi, Serena Robertson, Rebecca Harvey, Mary Brown Dec 2016

Wave Motion Induced By Turbulent Shear Flows Over Growing Stokes Waves, Shahrdad Sajjadi, Serena Robertson, Rebecca Harvey, Mary Brown

Publications

The recent analytical of multi-layer analyses proposed by Sajjadi et al. (J Eng Math 84:73, 2014) (SHD14 therein) is solved numerically for atmospheric turbulent shear flows blowing over growing (or unsteady) Stokes (bimodal) water waves, of low-to-moderate steepness. For unsteady surface waves, the amplitude a(t)∝ekcita(t)∝ekcit, where kcikci is the wave growth factor, k is the wavenumber, and cici is the complex part of the wave phase speed, and thus, the waves begin to grow as more energy is transferred to them by the wind. This will then display the critical height to a point, where ...


Tests Of Lorentz Symmetry In The Gravitational Sector, Aurélien Hees, Quentin G. Bailey, Adrien Bourgoin, Hélène Pihan-Le Bars, Christine Guerlin, Christophe Le Poncin-Lafitte Dec 2016

Tests Of Lorentz Symmetry In The Gravitational Sector, Aurélien Hees, Quentin G. Bailey, Adrien Bourgoin, Hélène Pihan-Le Bars, Christine Guerlin, Christophe Le Poncin-Lafitte

Publications

Lorentz symmetry is one of the pillars of both General Relativity and the Standard Model of particle physics. Motivated by ideas about quantum gravity, unification theories and violations of CPT symmetry, a significant effort has been put the last decades into testing Lorentz symmetry. This review focuses on Lorentz symmetry tests performed in the gravitational sector. We briefly review the basics of the pure gravitational sector of the Standard-Model Extension (SME) framework, a formalism developed in order to systematically parametrize hypothetical violations of the Lorentz invariance. Furthermore, we discuss the latest constraints obtained within this formalism including analyses of the ...


Anisotropic Cubic Curvature Couplings, Quentin G. Bailey Sep 2016

Anisotropic Cubic Curvature Couplings, Quentin G. Bailey

Publications

To complement recent work on tests of spacetime symmetry in gravity, cubic curvature couplings are studied using an effective field theory description of spacetime-symmetry breaking. The associated mass-dimension-eight coefficients for Lorentz violation studied do not result in any linearized gravity modifications and instead are revealed in the first nonlinear terms in an expansion of spacetime around a flat background. We consider effects on gravitational radiation through the energy loss of a binary system and we study two-body orbital perturbations using the post-Newtonian metric. Some effects depend on the internal structure of the source and test bodies, thereby breaking the weak ...


Growth Of Groups Of Wind Generated Waves, Frederique Drullion, Shahrdad Sajjadi Jul 2016

Growth Of Groups Of Wind Generated Waves, Frederique Drullion, Shahrdad Sajjadi

Publications

In this paper we demonstrate numerical computations of turbulent wind blowing over group of waves that are growing in time. The numerical model adopted for the turbulence model is based on differential second-moment model that was adopted for growing idealized waves by Drullion & Sajjadi (2014). The results obtained here demonstrate the formation of cat's-eye which appear asymmetrically over the waves within a group.


Growth Of Unsteady Wave Groups By Shear Flows, Shahrdad Sajjadi, Julian Hunt, Frederique Drullion Jul 2016

Growth Of Unsteady Wave Groups By Shear Flows, Shahrdad Sajjadi, Julian Hunt, Frederique Drullion

Publications

A weakly nonlinear theory has been proposed and developed for calculating the energy- transfer rate to individual waves in a group. It is shown what portion of total energy- transfer rate, over the envelope of wave group, affects individual waves in the group. From this an expression for complex phase speed of individual waves is calculated. It is deduced that each wave in a group does not grow at the same rate. It is shown that the critical layer is no longer symmetrical compared with the ideal monochromatic waves. This asymmetry causes the critical layer height to be lower over ...


Improved Tests Of Lorentz Invariance In The Matter Sector Using Atomic Clocks, H. Pihan-Le Bars, C. Guerlin, Q. G. Bailey, S. Bize, P. Wolf Jun 2016

Improved Tests Of Lorentz Invariance In The Matter Sector Using Atomic Clocks, H. Pihan-Le Bars, C. Guerlin, Q. G. Bailey, S. Bize, P. Wolf

Publications

For the purpose of searching for Lorentz-invariance violation in the minimal Standard-Model Extension, we perfom a reanalysis of data obtained from the 133Cs fountain clock operating at SYRTE. The previous study led to new limits on eight components of the ˜cµν tensor, which quantifies the anisotropy of the proton’s kinetic energy. We recently derived an advanced model for the frequency shift of hyperfine Zeeman transition due to Lorentz violation and became able to constrain the ninth component, the isotropic coefficient c˜TT, which is the least well-constrained coefficient of ˜cµν. This model is based on a second-order boost Lorentz ...


Gravity Sector Of The Sme, Q. G. Bailey Jun 2016

Gravity Sector Of The Sme, Q. G. Bailey

Publications

In this talk, the gravity sector of the effective field theory description of local Lorentz violation is discussed, including minimal and nonminimal curvature couplings. Also, recent experimental and observational analyses including solar-system ephemeris and short-range gravity tests are reviewed.


Prospects For Sme Tests With Experiments At Syrte And Lkb, C. Guerlin, H. Pihan-Le Bars, Q. G. Bailey, P. Wolf Jun 2016

Prospects For Sme Tests With Experiments At Syrte And Lkb, C. Guerlin, H. Pihan-Le Bars, Q. G. Bailey, P. Wolf

Publications

Preliminary work has been done in order to assess the perspectives of metrology and fundamental physics atomic experiments at SYRTE and LKB in the search for physics beyond the Standard Model and General Relativity. The first studies we identified are currently ongoing with the Microscope mission and with a Cs fountain clock. The latter brings significant improvement on the proton-sector coefficient cTT down to the 10−17 GeV level.


Ion Transport Through Macrocapillaries – Oscillations Due To Charge Patch Formation, Dhruva Kulkarni, L.A.M. Lyle, Chad E. Sosolik Apr 2016

Ion Transport Through Macrocapillaries – Oscillations Due To Charge Patch Formation, Dhruva Kulkarni, L.A.M. Lyle, Chad E. Sosolik

Publications

We present results on ion transport through large bore capillaries (macrocapillaries) that probe both the geometric and ion-guided aspects of this ion delivery mechanism. We have demonstrated that guiding in macrocapillaries exhibits position- and angle-dependent transmission properties which are directly related to the capillary material (either metal or insulator) and geometry. Specifically, we have passed 1 keV Rb+ ions through glass and metal macrocapillaries, and have observed oscillations for the transmitted ion current passing through the insulating capillaries. Straightforward calculations show that these oscillations can be attributed to beam deflections from charge patches that form on the interior walls of ...


Growth Of Stokes Waves Induced By Wind On A Viscous Liquid Of Infinite Depth, Shahrdad Sajjadi Apr 2016

Growth Of Stokes Waves Induced By Wind On A Viscous Liquid Of Infinite Depth, Shahrdad Sajjadi

Publications

The original investigation of Lamb (1932, x349) for the effect of viscosity on monochromatic surface waves is extended to account for second-order Stokes surface waves on deep water in the presence of surface tension. This extension is used to evaluate interfacial impedance for Stokes waves under the assumption that the waves are growing and hence the surface waves are unsteady. Thus, the previous investigation of Sajjadi et al. (2014) is further explored in that (i) the surface wave is unsteady and nonlinear, and (ii) the effect of the water viscosity, which affects surface stresses, is taken into account. The determination ...


Evolution Of Spherical Cavitation Bubbles: Parametric And Closed-Form Solutions, Stefan C. Mancas, Haret C. Rosu Feb 2016

Evolution Of Spherical Cavitation Bubbles: Parametric And Closed-Form Solutions, Stefan C. Mancas, Haret C. Rosu

Publications

We present an analysis of the Rayleigh-Plesset equation for a three dimensional vacuous bubble in water. In the simplest case when the effects of surface tension are neglected, the known parametric solutions for the radius and time evolution of the bubble in terms of a hypergeometric function are briefly reviewed. By including the surface tension, we show the connection between the Rayleigh-Plesset equation and Abel’s equation, and obtain the parametric rational Weierstrass periodic solutions following the Abel route. In the same Abel approach, we also provide a discussion of the nonintegrable case of nonzero viscosity for which we perform ...


How Uncertainty In The Neutral Wind Limits The Accuracy Of Ionospheric Modeling And Forecasting, Michael David, Jan J. Sojka, Robert W. Schunk Jan 2016

How Uncertainty In The Neutral Wind Limits The Accuracy Of Ionospheric Modeling And Forecasting, Michael David, Jan J. Sojka, Robert W. Schunk

Publications

One of the most important input fields for an ionospheric model is the horizontal neutral wind. The primary mechanism by which the neutral wind affects ionospheric densities is the inducement of an upward or downward ion drift along the magnetic field lines; this affects the rate at which ions are lost through recombination. The magnitude of this effect depends upon the dip angle of the magnetic field; for this reason, the impact of the neutral wind is somewhat less in polar regions than at mid-latitudes. It is unfortunate that observations of the neutral wind are relatively scarce, as compared for ...