Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Series

Michigan Technological University

Articles 1 - 30 of 165

Full-Text Articles in Physics

Richardsite, Zn2cugas4, A New Gallium-Essential Member Of The Stannite Group From The Gem Mines Near Merelani, Tanzania, Luca Bindi, John A. Jaszczak May 2020

Richardsite, Zn2cugas4, A New Gallium-Essential Member Of The Stannite Group From The Gem Mines Near Merelani, Tanzania, Luca Bindi, John A. Jaszczak

Michigan Tech Publications

The new mineral richardsite occurs as overgrowths of small (50–400 μm) dark gray, disphenoidal crystals with no evident twinning, but epitaxically oriented on wurtzite–sphalerite crystals from the gem mines near Merelani, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania. Associated minerals also include graphite, diopside, and Ge,Ga-rich wurtzite. It is brittle, dark gray in color, and has a metallic luster. It appears dark bluish gray in reflected plane-polarized light, and is moderately bireflectant. It is distinctly anisotropic with violet to light-blue rotation tints with crossed polarizers. Reflectance percentages for Rmin and Rmax in air at the respective wavelengths ...


Secular Changes In Atmospheric Turbidity Over Iraq And A Possible Link To Military Activity, Alexandra Chudnovsky, A. Kostinski May 2020

Secular Changes In Atmospheric Turbidity Over Iraq And A Possible Link To Military Activity, Alexandra Chudnovsky, A. Kostinski

Michigan Tech Publications

We examine satellite-derived aerosol optical depth (AOD) data during the period 2000-2018 over the Middle East to evaluate the contribution of anthropogenic pollution. We focus on Iraq, where US troops were present for nearly nine years. We begin with a plausibility argument linking anthropogenic influence and AOD signature. We then calculate the percent change in AOD every two years. To pinpoint the causes for changes in AOD on a spatial basis, we distinguish between synoptically "calm" periods and those with vigorous synoptic activity. This was done on high-resolution 10 km AOD retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor ...


Radiative Absorption Enhancements By Black Carbon Controlled By Particle-To-Particle Heterogeneity In Composition, Laura Fierce, Timothy B. Onasch, Christopher D. Cappa, Claudio Mazzoleni, Swarup China, Janarjan Bhandari, Et Al. Jan 2020

Radiative Absorption Enhancements By Black Carbon Controlled By Particle-To-Particle Heterogeneity In Composition, Laura Fierce, Timothy B. Onasch, Christopher D. Cappa, Claudio Mazzoleni, Swarup China, Janarjan Bhandari, Et Al.

Michigan Tech Publications

Black carbon (BC) absorbs solar radiation, leading to a strong but uncertain warming effect on climate. A key challenge in modeling and quantifying BC’s radiative effect on climate is predicting enhancements in light absorption that result from internal mixing between BC and other aerosol components. Modeling and laboratory studies show that BC, when mixed with other aerosol components, absorbs more strongly than pure, uncoated BC; however, some ambient observations suggest more variable and weaker absorption enhancement. We show that the lower-than-expected enhancements in ambient measurements result from a combination of two factors. First, the often used spherical, concentric core-shell ...


Phase Diagrams Of Polymer-Containing Liquid Mixtures With A Theory-Embedded Neural Network, Issei Nakamura Jan 2020

Phase Diagrams Of Polymer-Containing Liquid Mixtures With A Theory-Embedded Neural Network, Issei Nakamura

Michigan Tech Publications

We develop a deep neural network (DNN) that accounts for the phase behaviors of polymer-containing liquid mixtures. The key component in the DNN consists of a theory-embedded layer that captures the characteristic features of the phase behavior via coarse-grained mean-field theory and scaling laws and substantially enhances the accuracy of the DNN. Moreover, this layer enables us to reduce the size of the DNN for the phase diagrams of the mixtures. This study also presents the predictive power of the DNN for the phase behaviors of polymer solutions and salt-free and salt-doped diblock copolymer melts.


Is Contact Nucleation Caused By Pressure Perturbation?, Fan Yang, Will Cantrell, Alexander Kostinski, Raymond Shaw, Andrew M. Vogelmann Dec 2019

Is Contact Nucleation Caused By Pressure Perturbation?, Fan Yang, Will Cantrell, Alexander Kostinski, Raymond Shaw, Andrew M. Vogelmann

Michigan Tech Publications

The reason why ice nucleation is more efficient by contact nucleation than by immersion nucleation has been elusive for over half a century. Six proposed mechanisms are summarized in this study. Among them, the pressure perturbation hypothesis, which arose from recent experiments, can qualitatively explain nearly all existing results relevant to contact nucleation. To explore the plausibility of this hypothesis in a more quantitative fashion and to guide future investigations, this study assessed the magnitude of pressure perturbation needed to cause contact nucleation and the associated spatial scales. The pressure perturbations needed were estimated using measured contact nucleation efficiencies for ...


Laboratory Study Of The Heterogeneous Ice Nucleation On Black-Carbon-Containing Aerosol, Leonid Nichman, Martin Wolf, Paul Davidovits, Timothy Onasch, Yue Zhang, Doug Worsnop, Janarjan Bhandari, Claudio Mazzoleni, Daniel Cziczo Oct 2019

Laboratory Study Of The Heterogeneous Ice Nucleation On Black-Carbon-Containing Aerosol, Leonid Nichman, Martin Wolf, Paul Davidovits, Timothy Onasch, Yue Zhang, Doug Worsnop, Janarjan Bhandari, Claudio Mazzoleni, Daniel Cziczo

Michigan Tech Publications

Soot and black carbon (BC) particles are generated in the incomplete combustion of fossil fuels, biomass, and biofuels. These airborne particles affect air quality, human health, aerosol–cloud interactions, precipitation formation, and climate. At present, the climate effects of BC particles are not well understood. Their role in cloud formation is obscured by their chemical and physical variability and by the internal mixing states of these particles with other compounds. Ice nucleation in field studies is often difficult to interpret. Nonetheless, most field studies seem to suggest that BC particles are not efficient ice-nucleating particles (INPs). On the other hand ...


Extensive Soot Compaction By Cloud Processing From Laboratory And Field Observations, Janarjan Bhandari, Swarup China, Kamal Kant Chandrakar, Greg Kinney, Will Cantrell, Raymond Shaw, Lynn Mazzoleni, Giulia Girotto, Noopur Sharma, Kyle Gorkowski, Stefania Gilardoni, Stefano Decesari, Maria Cristina Facchini, Nicola Zanca, Giulia Pavese, Francesco Esposito, Manvendra K Dubey, Allison C Aiken, Rajan K Chakrabarty, Hans Moosmüller, Timothy B Onasch, Rahul A Zaveri, Barbara V Scarnato, Paulo Fialho, Claudio Mazzoleni Aug 2019

Extensive Soot Compaction By Cloud Processing From Laboratory And Field Observations, Janarjan Bhandari, Swarup China, Kamal Kant Chandrakar, Greg Kinney, Will Cantrell, Raymond Shaw, Lynn Mazzoleni, Giulia Girotto, Noopur Sharma, Kyle Gorkowski, Stefania Gilardoni, Stefano Decesari, Maria Cristina Facchini, Nicola Zanca, Giulia Pavese, Francesco Esposito, Manvendra K Dubey, Allison C Aiken, Rajan K Chakrabarty, Hans Moosmüller, Timothy B Onasch, Rahul A Zaveri, Barbara V Scarnato, Paulo Fialho, Claudio Mazzoleni

Michigan Tech Publications

Soot particles form during combustion of carbonaceous materials and impact climate and air quality. When freshly emitted, they are typically fractal-like aggregates. After atmospheric aging, they can act as cloud condensation nuclei, and water condensation or evaporation restructure them to more compact aggregates, affecting their optical, aerodynamic, and surface properties. Here we survey the morphology of ambient soot particles from various locations and different environmental and aging conditions. We used electron microscopy and show extensive soot compaction after cloud processing. We further performed laboratory experiments to simulate atmospheric cloud processing under controlled conditions. We find that soot particles sampled after ...


Astro2020 Apc White Paper: Elevating The Role Of Software As A Product Of The Research Enterprise, Arfon Smith, Dara Norman, Kelle Cruz, Vandana Desai, Eric Bellm, Robert J. Nemiroff, Et. Al. Jul 2019

Astro2020 Apc White Paper: Elevating The Role Of Software As A Product Of The Research Enterprise, Arfon Smith, Dara Norman, Kelle Cruz, Vandana Desai, Eric Bellm, Robert J. Nemiroff, Et. Al.

Michigan Tech Publications

Software is a critical part of modern research, and yet there are insufficient mechanisms in the scholarly ecosystem to acknowledge, cite, and measure the impact of research software. The majority of academic fields rely on a one-dimensional credit model whereby academic articles (and their associated citations) are the dominant factor in the success of a researcher's career. In the petabyte era of astronomical science, citing software and measuring its impact enables academia to retain and reward researchers that make significant software contributions. These highly skilled researchers must be retained to maximize the scientific return from petabyte-scale datasets. Evolving beyond ...


Searching For Dark Matter Sub-Structure With Hawc, A. U. Abeysekara, A. Albert, R. Alfaro, C. Alvarez, R. Arceo, J. C. Arteaga-Valazquez, Chad Brisbois, H. Fleischhack, Binita Hona, P. Huntemeyer, Et Al. Jul 2019

Searching For Dark Matter Sub-Structure With Hawc, A. U. Abeysekara, A. Albert, R. Alfaro, C. Alvarez, R. Arceo, J. C. Arteaga-Valazquez, Chad Brisbois, H. Fleischhack, Binita Hona, P. Huntemeyer, Et Al.

Michigan Tech Publications

Numerical simulations show that the dark matter halos surrounding galaxies are expected to contain many over-densities or sub-halos. The most massive of these sub-halos can be optically observed in the form of dwarf galaxies. However, most lower mass sub-halos are predicted to exist as dark dwarf galaxies: sub-halos like dwarf galaxies with no luminous counterpart. It may be possible to detect these unseen sub-halos from gamma-ray signals originating from dark matter annihilation. The High Altitude Water Cherenkov Observatory (HAWC) is a very high energy (500 GeV to >100 TeV) gamma ray detector with a wide field-of-view and near continuous duty ...


Scaling Of An Atmospheric Model To Simulate Turbulence And Cloud Microphysics In The Pi Chamber, Subin Thomas, Mikhail Ovichinnikov, Fan Yang, Dennis Van Der Voort, Will Cantrell, Steven K. Krueger, Raymond Shaw Jul 2019

Scaling Of An Atmospheric Model To Simulate Turbulence And Cloud Microphysics In The Pi Chamber, Subin Thomas, Mikhail Ovichinnikov, Fan Yang, Dennis Van Der Voort, Will Cantrell, Steven K. Krueger, Raymond Shaw

Michigan Tech Publications

The Pi Cloud Chamber offers a unique opportunity to study aerosol-cloud microphysics interactions in a steady-state, turbulent environment. In this work, an atmospheric large-eddy simulation (LES) model with spectral bin microphysics is scaled down to simulate these interactions, allowing comparison with experimental results. A simple scalar flux budget model is developed and used to explore the effect of sidewalls on the bulk mixing temperature, water vapor mixing ratio, and supersaturation. The scaled simulation and the simple scalar flux budget model produce comparable bulk mixing scalar values. The LES dynamics results are compared with particle image velocimetry measurements of turbulent kinetic ...


Data Supporting The Paper "Aerosol Mediated Glaciation Of Mixed-Phase Clouds: Steady-State Laboratory Measurements", N. Desai, K. K. Chandrakar, G. Kinney, W. Cantrell, R. A. Shaw Jun 2019

Data Supporting The Paper "Aerosol Mediated Glaciation Of Mixed-Phase Clouds: Steady-State Laboratory Measurements", N. Desai, K. K. Chandrakar, G. Kinney, W. Cantrell, R. A. Shaw

Department of Physics Publications

No abstract provided.


Tailoring Of The Electronic Property Of Zn-Btc Metal–Organic Framework Via Ligand Functionalization: An Ab Initio Investigation, Gemechis Degaga, Ravindra Pandey, Chansi Gupta, Lalit Bharadwaj May 2019

Tailoring Of The Electronic Property Of Zn-Btc Metal–Organic Framework Via Ligand Functionalization: An Ab Initio Investigation, Gemechis Degaga, Ravindra Pandey, Chansi Gupta, Lalit Bharadwaj

Department of Physics Publications

Metal–organic frameworks (MOFs) are porous materials of recent interest due to their promising properties for technological applications. In this paper, the structure–property relationships of pristine and functionalized Zn-BTC (Zn3(BTC)2) MOFs are investigated. The results based on density functional theory (DFT) find that MOFs with coordinatively saturated secondary building units (SBU) are metallic, and MOFs with coordinatively unsaturated SBU are semi-conducting. The ligand functionalization with electron acceptor (cyano-) and electron donor (amino-) groups appears to tailor the electronic properties of Zn-BTC MOFs; amino-functionalization led to a significant upward shift of the band-edges whereas cyano-functionalization ...


Turbulence-Induced Cloud Voids: Observation And Interpretation, Katarzyna Karpinska, Jonathan F. E. Bodenschatz, Szymon P. Malinowski, Jakub L. Nowak, Steffen Risius, Tina Schmeissner, Raymond Shaw, Holger Siebert, Hengdong Xi, Haitao Xu, Eberhard Bodenschatz Apr 2019

Turbulence-Induced Cloud Voids: Observation And Interpretation, Katarzyna Karpinska, Jonathan F. E. Bodenschatz, Szymon P. Malinowski, Jakub L. Nowak, Steffen Risius, Tina Schmeissner, Raymond Shaw, Holger Siebert, Hengdong Xi, Haitao Xu, Eberhard Bodenschatz

Michigan Tech Publications

The phenomenon of “cloud voids”, i.e., elongated volumes inside a cloud that are devoid of droplets, was observed with laser sheet photography in clouds at a mountain-top station. Two experimental cases, similar in turbulence conditions yet with diverse droplet size distributions and cloud void prevalence, are reported. A theoretical explanation is proposed based on the study of heavy inertial sedimenting particles inside a Burgers vortex. A general conclusion regarding void appearance is drawn from theoretical analysis. Numerical simulations of polydisperse droplet motion with realistic vortex parameters and Mie scattering visual effects accounted for can explain the presence of voids ...


Leidenfrost Pattern Formation And Boiling, Prasanth Prabhakaran, Alexei Krekhov, Eberhard Bodenschatz, Stephan Weiss Apr 2019

Leidenfrost Pattern Formation And Boiling, Prasanth Prabhakaran, Alexei Krekhov, Eberhard Bodenschatz, Stephan Weiss

Department of Physics Publications

We report on Leidenfrost patterns and boiling with compressed sulfur hexafluoride ( SF6). The experiments were carried out in a large aspect ratio Rayleigh–Bénard convection cell, where the distance between the horizontal plates is comparable with the capillary length of the working fluid. Pressures and temperatures were chosen such that the bottom plate was above and the top plate was below the liquid–vapor transition temperature of SF6. As a result, SF6 vapor condenses at the top plate and forms drops that grow in size. Leidenfrost patterns are formed as the drops do not fall but levitate ...


The Dawn Of Non-Hermitian Optics, Ramy El-Ganainy, Mercedeh Khajavikhan, Demetrios Christodoulides, Sahin Ozdemir Mar 2019

The Dawn Of Non-Hermitian Optics, Ramy El-Ganainy, Mercedeh Khajavikhan, Demetrios Christodoulides, Sahin Ozdemir

Department of Physics Publications

Recent years have seen a tremendous progress in the theory and experimental implementations of non-Hermitian photonics, including all-lossy optical systems as well as parity-time symmetric systems consisting of both optical loss and gain. This progress has led to a host of new intriguing results in the physics of light–matter interactions with promising potential applications in optical sciences and engineering. In this comment, we present a brief perspective on the developments in this field and discuss possible future research directions that can benefit from the notion of non-Hermitian engineering.


Data Supporting The Paper "Extensive Soot Compaction By Cloud Processing From Laboratory And Field Observations", Janarjan Bhandari, Swarup China, Kamal Kant Chandrakar, Greg Kinney, Will Cantrell, Raymond Shaw, Lynn R. Mazzoleni, Giulia Girotto, Noopur Sharma, Kyle Gorkowski, Stefania Gilardoni, Stefano Decesari, Maria Cristina Facchini, Nicola Zanca, Giulia Pavese, Francesco Esposito, Manvendra Dubey, Allison Aiken, Rajan K. Chakrabarty, Hans Moosmüller, Timothy B. Onasch, Rahul A. Zaveri, Barbara Scarnato, Paolo Fialho, Claudio Mazzoleni Feb 2019

Data Supporting The Paper "Extensive Soot Compaction By Cloud Processing From Laboratory And Field Observations", Janarjan Bhandari, Swarup China, Kamal Kant Chandrakar, Greg Kinney, Will Cantrell, Raymond Shaw, Lynn R. Mazzoleni, Giulia Girotto, Noopur Sharma, Kyle Gorkowski, Stefania Gilardoni, Stefano Decesari, Maria Cristina Facchini, Nicola Zanca, Giulia Pavese, Francesco Esposito, Manvendra Dubey, Allison Aiken, Rajan K. Chakrabarty, Hans Moosmüller, Timothy B. Onasch, Rahul A. Zaveri, Barbara Scarnato, Paolo Fialho, Claudio Mazzoleni

Department of Physics Publications

No abstract provided.


Natural Graphite Cuboids, Andrey Korsakov, Olga V. Rezvukhina, John Jaszczak, Dmitriy I. Rezvukhin, Denis Mikhailenko Feb 2019

Natural Graphite Cuboids, Andrey Korsakov, Olga V. Rezvukhina, John Jaszczak, Dmitriy I. Rezvukhin, Denis Mikhailenko

Department of Physics Publications

Graphite cuboids are abundant in ultrahigh-pressure metamorphic rocks and are generally interpreted as products of partial or complete graphitization of pre-existing diamonds. The understanding of the graphite cuboid structure and its formation mechanisms is still very limited compared to nanotubes, cones, and other carbon morphologies. This paper is devoted to the natural occurrences of graphite cuboids in several metamorphic and magmatic rocks, including diamondiferous metamorphic assemblages. The studied cuboids are polycrystalline aggregates composed either of numerous smaller graphite cuboids with smooth surfaces or graphite flakes radiating from a common center. Silicates, oxides, and sulphides are abundant in all the samples ...


Data Supporting The Paper "Scaling Of An Atmospheric Model To Simulate Turbulence And Cloud Microphysics In The Pi Chamber", Subin Thomas, Mikhail S. Ovchinnikov, Fan Yang, Dennis Van Der Voort, Will Cantrell, Steven K. Krueger, Raymond Shaw Feb 2019

Data Supporting The Paper "Scaling Of An Atmospheric Model To Simulate Turbulence And Cloud Microphysics In The Pi Chamber", Subin Thomas, Mikhail S. Ovchinnikov, Fan Yang, Dennis Van Der Voort, Will Cantrell, Steven K. Krueger, Raymond Shaw

Department of Physics Publications

No abstract provided.


Studies Of The Time Structure Of Extended Air Showers For Direction Reconstruction With The Hawc Outrigger Array, Dezhi Huang Jan 2019

Studies Of The Time Structure Of Extended Air Showers For Direction Reconstruction With The Hawc Outrigger Array, Dezhi Huang

Michigan Tech Publications

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a ground-based air shower array designed to detect Cherenkov light produced in water by secondary particles from atmospheric air showers. In order to improve the sensitivity at the highest energies, especially for the shower cores falling outside the main array, 345 smaller Water Cherenkov Detectors (WCDs) were installed around the main array, the outrigger array. This extension increased the instrumented area of HAWC by a factor of four. With the increased size of the array, and the ability to detect shower particles further away from the core, understanding of the time ...


Electron Spectrum Of The Dragonfly Pulsar Wind Nebula From X-Ray To Tev, Chad Brisbois, V. Joshi Jan 2019

Electron Spectrum Of The Dragonfly Pulsar Wind Nebula From X-Ray To Tev, Chad Brisbois, V. Joshi

Michigan Tech Publications

The Dragonfly nebula is a Vela-like Pulsar Wind Nebula (PWN) in the Cygnus region powered by the spin down of PSR J2021+3651. In X-rays, the inner nebula is a few arcseconds across, whereas at TeV energies VERITAS and HAWC has observed extended emission much larger than the extension in X-rays. The TeV gamma-ray source HAWC J2019+368 was originally discovered in 2007 by the Milagro Observatory and has been associated with this pulsar. Recent work has shown hints of energy dependent morphology for the source at TeV energies, supporting the interpretation of the gamma-ray emission being due to Inverse ...


First Galactic Survey Of Energy-Dependent Diffusion By Hawc, Chad Brisbois, Hao Zhou Jan 2019

First Galactic Survey Of Energy-Dependent Diffusion By Hawc, Chad Brisbois, Hao Zhou

Michigan Tech Publications

HAWC’s wide field-of-view enables unbiased observations of much of the galaxy, allowing for analysis of many candidate sources in the HAWC dataset. Recent work has allowed HAWC to start investigating electron diffusion around pulsars at TeV energies. Surveying electron diffusion at TeV energies along the galactic plane is a unique capability of HAWC that allows us to examine the sources of electrons in our galaxy and constrain the energy dependence of the diffusion mech-anism. HAWC has already applied this model to the Geminga and Monogem pulsars. This work will expand the study to include multiple sources associated with pulsars ...


Testing The Limits Of Particle Acceleration In Cygnus Ob2 With Hawc, Binita Hona, H. Fleischhack, Petra Huentemeyer Jan 2019

Testing The Limits Of Particle Acceleration In Cygnus Ob2 With Hawc, Binita Hona, H. Fleischhack, Petra Huentemeyer

Michigan Tech Publications

Star forming regions (SFRs) have been postulated as possible sources of cosmic rays (CRs) in our galaxy. One example of a gamma-ray source associated with an SFR is the Fermi-LAT cocoon, an extended region of gamma-ray emission in the Cygnus X region and attributed to a possible superbubble with freshly accelerated CRs. Because the emission region is surrounded by ionization fronts, it has been named the Cygnus cocoon. CRs in the cocoon could have originated in the OB2 association and been accelerated at the interaction sites of stellar winds of massive O type stars. So far, there is no clear ...


Introduction To The Second Special Issue On Biological Mentality, Kenneth Augustyn Jan 2019

Introduction To The Second Special Issue On Biological Mentality, Kenneth Augustyn

Michigan Tech Publications

No abstract provided.


Physical Foundations Of Biological Mentality, Kenneth Augustyn Jan 2019

Physical Foundations Of Biological Mentality, Kenneth Augustyn

Michigan Tech Publications

Dualism struggles to connect two layers: the conscious mind and the physical workings of matter. It ignores a vast middle layer between the two, a layer that is beneath consciousness yet above known physical law. This middle layer is trans-robotic mentality, a means discovered by Nature to transcend robotic mentality. This middle layer evolved over billions of years before consciousness emerged from it, assuming more and more functions critical to survival as species evolved. Consciousness eventually emerged from trans-robotic mentality (not from robotic mentality), first intermittently then later more-or-less continuously. But there is no direct link between consciousness and matter ...


Revisiting The Paleomagnetism Of The Neoarchean Uauá Mafic Dyke Swarm, Brazil: Implications For Archean Supercratons, J. Salminen, E. P. Oliveira, Elisa J. Piispa, Aleksey Smirnov, R. I. F. Trindade Dec 2018

Revisiting The Paleomagnetism Of The Neoarchean Uauá Mafic Dyke Swarm, Brazil: Implications For Archean Supercratons, J. Salminen, E. P. Oliveira, Elisa J. Piispa, Aleksey Smirnov, R. I. F. Trindade

Michigan Tech Publications

The original connections of Archean cratons are becoming traceable due to an increasing amount of paleomagnetic data and refined magmatic barcodes. The Uauá block of the northern São Francisco craton may represent a fragment of a major Archean craton. Here, we report new paleomagnetic data from the 2.62 Ga Uauá tholeiitic mafic dyke swarm of the Uauá block in the northern São Francisco craton, Eastern Brazil. Our paleomagnetic results confirm the earlier results for these units, but our interpretation differs. We suggest that the obtained characteristic remanent magnetization for the 2.62 Ga swarm is of primary origin, supported ...


Winding Around Non-Hermitian Singularities, Qi Zhong, Mercedeh Khajavikhan, Demetrios Christodoulides, Ramy El-Ganainy Nov 2018

Winding Around Non-Hermitian Singularities, Qi Zhong, Mercedeh Khajavikhan, Demetrios Christodoulides, Ramy El-Ganainy

Department of Physics Publications

Non-Hermitian singularities are ubiquitous in non-conservative open systems. Owing to their peculiar topology, they can remotely induce observable effects when encircled by closed trajectories in the parameter space. To date, a general formalism for describing this process beyond simple cases is still lacking. Here we develop a general approach for treating this problem by utilizing the power of permutation operators and representation theory. This in turn allows us to reveal a surprising result that has so far escaped attention: loops that enclose the same singularities in the parameter space starting from the same point and traveling in the same direction ...


Fine-Scale Droplet Clustering In Atmospheric Clouds: 3d Radial Distribution Function From Airborne Digital Holography, Michael L. Larsen, Raymond Shaw, Alexander Kostinski, Susanne Glienke Nov 2018

Fine-Scale Droplet Clustering In Atmospheric Clouds: 3d Radial Distribution Function From Airborne Digital Holography, Michael L. Larsen, Raymond Shaw, Alexander Kostinski, Susanne Glienke

Department of Physics Publications

The extent of droplet clustering in turbulent clouds has remained largely unquantified, and yet is of possible relevance to precipitation formation and radiative transfer. To that end, data gathered by an airborne holographic instrument are used to explore the three-dimensional spatial statistics of cloud droplet positions in homogeneous stratiform boundary-layer clouds. The three-dimensional radial distribution functions g(r) reveal unambiguous evidence of droplet clustering. Three key theoretical predictions are observed: the existence of positive correlations, onset of correlation in the turbulence dissipation range, and monotonic increase of g(r) with decreasing r. This implies that current theory captures the essential ...


Scale Dependence Of Cloud Microphysical Response To Turbulent Entrainment And Mixing, Bipin Kumar, Paul Gotzfried, Neethl Suresh, Jörg Schumacher, Raymond Shaw Oct 2018

Scale Dependence Of Cloud Microphysical Response To Turbulent Entrainment And Mixing, Bipin Kumar, Paul Gotzfried, Neethl Suresh, Jörg Schumacher, Raymond Shaw

Michigan Tech Publications

The dynamics and lifetime of atmospheric clouds are tightly coupled to entrainment and turbulent mixing. This paper presents direct numerical simulations of turbulent mixing followed by droplet evaporation at the cloud‐clear air interface in a meter‐sized volume, with an ensemble of up to almost half a billion individual cloud water droplets. The dependence of the mixing process on domain size reveals that inhomogeneous mixing becomes increasingly important as the domain size is increased. The shape of the droplet size distribution varies strongly with spatial scale, with the appearance of a pronounced negative exponential tail. The increase of relative ...


Turbulence Induced Cloud Voids: Observation And Interpretation, Katarzyna Karpinska, Jonathan F. E. Bodenschatz, Szymon P. Malinowski, Jakub L. Nowak, Steffen Risius, Tina Schmeissner, Raymond Shaw, Holger Siebert, Hengdong Xi, Haitao Xu, Eberhard Bodenschatz Oct 2018

Turbulence Induced Cloud Voids: Observation And Interpretation, Katarzyna Karpinska, Jonathan F. E. Bodenschatz, Szymon P. Malinowski, Jakub L. Nowak, Steffen Risius, Tina Schmeissner, Raymond Shaw, Holger Siebert, Hengdong Xi, Haitao Xu, Eberhard Bodenschatz

Department of Physics Publications

The phenomenon of cloud voids, i.e., elongated volumes inside a cloud that are devoid of droplets, was observed with laser sheet photography in clouds at a mountain-top station. Two experimental cases, similar in turbulence conditions yet with diverse droplet size distributions and cloud void prevalence, are reported. A theoretical explanation is proposed based on the study of heavy inertial sedimenting particles inside a Burgers vortex. A general conclusion regarding void appearance is drawn from theoretical analysis. Numerical simulations of polydisperse droplet motion with realistic vortex parameters and Mie scattering visual effects accounted for can explain the presence of voids ...


Molecular And Physical Characteristics Of Aerosol At A Remote Free Troposphere Site: Implications For Atmospheric Aging, Simeon Schum, Bo Zhang, Katja Džepina, Paolo Fialho, Claudio Mazzoleni, Lynn Mazzoleni Oct 2018

Molecular And Physical Characteristics Of Aerosol At A Remote Free Troposphere Site: Implications For Atmospheric Aging, Simeon Schum, Bo Zhang, Katja Džepina, Paolo Fialho, Claudio Mazzoleni, Lynn Mazzoleni

Department of Chemistry Publications

Aerosol properties are transformed by atmospheric processes during long-range transport and play a key role in the Earth's radiative balance. To understand the molecular and physical characteristics of free tropospheric aerosol, we studied samples collected at the Pico Mountain Observatory in the North Atlantic. The observatory is located in the marine free troposphere at 2225m above sea level, on Pico Island in the Azores archipelago. The site is ideal for the study of long-range-transported free tropospheric aerosol with minimal local influence. Three aerosol samples with elevated organic carbon concentrations were selected for detailed analysis. FLEXPART retroplumes indicated that two ...