Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Department of Physics (8)
- Department of Electrical and Computer Engineering (1)
- Dielectric resonator (1)
- Direct band-gap (1)
- Drop size distribution (1)
-
- Electronic band structure (1)
- Electronic properties and materials (1)
- Fano resonance (1)
- Metamaterial (1)
- Microscale processes/variability (1)
- Molybdenum disulfide (1)
- Nanoscale materials (1)
- Photoluminescence (PL) spectroscopy (1)
- Precipitation (1)
- Rainfall (1)
- Raman spectroscopy (1)
- Resonant Raman scattering (1)
- Statistical techniques (1)
- Statistics (1)
- Surface observations (1)
- Time series (1)
Articles 1 - 13 of 13
Full-Text Articles in Physics
Ice Nucleation At The Contact Line Triggered By Transient Electrowetting Fields, Fan Yang, Raymond Shaw, Colin Gurganus, Su Kong Chong, Yoke Khin Yap
Ice Nucleation At The Contact Line Triggered By Transient Electrowetting Fields, Fan Yang, Raymond Shaw, Colin Gurganus, Su Kong Chong, Yoke Khin Yap
Department of Physics Publications
Supercooled water is found to have a significantly enhanced freezing temperature during transient electrowetting with electric fields of order 1 V/μm. High speed imaging reveals that the nucleation occurs randomly at the three-phase contact line (droplet perimeter) and can occur at multiple points during one freezing event. Possible nucleation mechanisms are explored by testing various substrate geometries and materials. Results demonstrate that electric field alone has no detectable effect on ice nucleation, but the moving boundary of the droplet on the substrate due to electrowetting is associated with the triggering of nucleation at a much higher temperature.
Observations Of New Particle Formation In Enhanced Uv Irradiance Zones Near Cumulus Clouds, B. Wehner, F. Werner, F. Ditas, R. A. Shaw, M. Kulmala, H. Siebert
Observations Of New Particle Formation In Enhanced Uv Irradiance Zones Near Cumulus Clouds, B. Wehner, F. Werner, F. Ditas, R. A. Shaw, M. Kulmala, H. Siebert
Michigan Tech Publications
During the CARRIBA (Cloud, Aerosol, Radiation and tuRbulence in the trade wInd regime over Barbados) campaign, the interaction between aerosol particles and cloud microphysical properties was investigated in detail, which also includes the influence of clouds on the aerosol formation. During two intensive campaigns in 2010 and 2011, helicopter-borne measurement flights were performed to investigate the thermodynamic, turbulent, microphysical, and radiative properties of trade-wind cumuli over Barbados. During these flights, 91 cases with increased aerosol particle number concentrations near clouds were detected. The majority of these cases are also correlated with enhanced irradiance in the ultraviolet (UV) spectral wavelength range. …
Schneefernerhaus As A Mountain Research Station For Clouds And Turbulence, S. Risius, H. Xu, F. Di Lorenzo, H. Xi, H. Siebert, R. A. Shaw, E. Bodenschatz
Schneefernerhaus As A Mountain Research Station For Clouds And Turbulence, S. Risius, H. Xu, F. Di Lorenzo, H. Xi, H. Siebert, R. A. Shaw, E. Bodenschatz
Michigan Tech Publications
Cloud measurements are usually carried out with airborne campaigns, which are expensive and are limited by temporal duration and weather conditions. Ground-based measurements at high-altitude research stations therefore play a complementary role in cloud study. Using the meteorological data (wind speed, direction, temperature, humidity, visibility, etc.) collected by the German Weather Service (DWD) from 2000 to 2012 and turbulence measurements recorded by multiple ultrasonic sensors (sampled at 10 Hz) in 2010, we show that the Umweltforschungsstation Schneefernerhaus (UFS) located just below the peak of Zugspitze in the German Alps, at a height of 2650 m, is a well-suited station for …
High-Resolution Measurement Of Cloud Microphysics And Turbulence At A Mountaintop Station, H. Siebert, R. A. Shaw, J. Ditas, T. Schmeissner, S. P. Malinowski, E. Bodenschatz, H. Xu
High-Resolution Measurement Of Cloud Microphysics And Turbulence At A Mountaintop Station, H. Siebert, R. A. Shaw, J. Ditas, T. Schmeissner, S. P. Malinowski, E. Bodenschatz, H. Xu
Michigan Tech Publications
Mountain research stations are advantageous not only for long-term sampling of cloud properties but also for measurements that are prohibitively difficult to perform on airborne platforms due to the large true air speed or adverse factors such as weight and complexity of the equipment necessary. Some cloud-turbulence measurements, especially Lagrangian in nature, fall into this category. We report results from simultaneous, high-resolution and collocated measurements of cloud microphysical and turbulence properties during several warm cloud events at the Umweltforschungsstation Schneefernerhaus (UFS) on Zugspitze in the German Alps. The data gathered were found to be representative of observations made with similar …
Switching Behaviors Of Graphene-Boron Nitride Nanotube Heterojunctions, Vyom Parashar, Corentin Durand, Boyi Hao, Rodrigo Amorim, Ravindra Pandey, Bishnu Tiwari, Dongyan Zhang, Yang Liu, An-Ping Li, Yoke Khin Yap
Switching Behaviors Of Graphene-Boron Nitride Nanotube Heterojunctions, Vyom Parashar, Corentin Durand, Boyi Hao, Rodrigo Amorim, Ravindra Pandey, Bishnu Tiwari, Dongyan Zhang, Yang Liu, An-Ping Li, Yoke Khin Yap
Department of Physics Publications
High electron mobility of graphene has enabled their application in high-frequency analogue devices but their gapless nature has hindered their use in digital switches. In contrast, the structural analogous, h-BN sheets and BN nanotubes (BNNTs) are wide band gap insulators. Here we show that the growth of electrically insulating BNNTs on graphene can enable the use of graphene as effective digital switches. These graphene-BNNT heterojunctions were characterized at room temperature by four-probe scanning tunneling microscopy (4-probe STM) under real-time monitoring of scanning electron microscopy (SEM). A switching ratio as high as 105 at a turn-on voltage as low …
Perturbations Of The Optical Properties Of Mineral Dust Particles By Mixing With Black Carbon: A Numerical Simulation Study, B. V. Scarnato, S. China, K. Nielsen, C. Mazzoleni
Perturbations Of The Optical Properties Of Mineral Dust Particles By Mixing With Black Carbon: A Numerical Simulation Study, B. V. Scarnato, S. China, K. Nielsen, C. Mazzoleni
Michigan Tech Publications
Field observations show that individual aerosol particles are a complex mixture of a wide variety of species, reflecting different sources and physico-chemical transformations. The impacts of individual aerosol morphology and mixing characteristics on the Earth system are not yet fully understood. Here we present a sensitivity study on climate-relevant aerosols optical properties to various approximations. Based on aerosol samples collected in various geographical locations, we have observationally constrained size, morphology and mixing, and accordingly simulated, using the discrete dipole approximation model (DDSCAT), optical properties of three aerosols types: (1) bare black carbon (BC) aggregates, (2) bare mineral dust, and (3) …
Ice Nucleation By Water-Soluble Macromolecules, B. G. Pummer, C. Budke, S. Augustin-Bauditz, D. Niedermeier, L. Felgitsch, C. J. Kampf, R. G. Huber, K. R. Liedl, T. Loerting, T. Moschen, M. Schauperl, M. Tollinger, C. E. Morris, H. Wex, H. Grothe, U. Pöschl, T. Koop, J. Fröhlich-Nowoisky
Ice Nucleation By Water-Soluble Macromolecules, B. G. Pummer, C. Budke, S. Augustin-Bauditz, D. Niedermeier, L. Felgitsch, C. J. Kampf, R. G. Huber, K. R. Liedl, T. Loerting, T. Moschen, M. Schauperl, M. Tollinger, C. E. Morris, H. Wex, H. Grothe, U. Pöschl, T. Koop, J. Fröhlich-Nowoisky
Michigan Tech Publications
Cloud glaciation is critically important for the global radiation budget (albedo) and for initiation of precipitation. But the freezing of pure water droplets requires cooling to temperatures as low as 235 K. Freezing at higher temperatures requires the presence of an ice nucleator, which serves as a template for arranging water molecules in an ice-like manner. It is often assumed that these ice nucleators have to be insoluble particles. We point out that also free macromolecules which are dissolved in water can efficiently induce ice nucleation: the size of such ice nucleating macromolecules (INMs) is in the range of nanometers, …
Sensing Based On Fano-Type Resonance Response Of All-Dielectric Metamaterials, Elena Semouchkina, Ran Duan, George Semouchkin, Ravindra Pandey
Sensing Based On Fano-Type Resonance Response Of All-Dielectric Metamaterials, Elena Semouchkina, Ran Duan, George Semouchkin, Ravindra Pandey
Michigan Tech Publications
A new sensing approach utilizing Mie resonances in metamaterial arrays composed of dielectric resonators is proposed. These arrays were found to exhibit specific, extremely high-Q factor (up to 15,000) resonances at frequencies corresponding to the lower edge of the array second transmission band. The observed resonances possessed with features typical for Fano resonances (FRs), which were initially revealed in atomic processes and recently detected in macro-structures, where they resulted from interference between local resonances and a continuum of background waves. Our studies demonstrate that frequencies and strength of Fano-type resonances in all-dielectric arrays are defined by interaction between local Mie …
Disdrometer Network Observations Of Finescale Spatial–Temporal Clustering In Rain, A. R. Jameson, M. L. Larsen, A. Kostinski
Disdrometer Network Observations Of Finescale Spatial–Temporal Clustering In Rain, A. R. Jameson, M. L. Larsen, A. Kostinski
Department of Physics Publications
The spatial clustering of drops is a defining characteristic of rain on all scales from centimeters to kilometers. It is the physical basis for much of the observed variability in rain. The authors report here on the temporal–spatial 1-min counts using a network of 21 optical disdrometers over a small area near Charleston, South Carolina. These observations reveal significant differences between spatial and temporal structures (i.e., clustering) for different sizes of drops, which suggest that temporal observations of clustering cannot be used to infer spatial clustering simply using by an advection velocity as has been done in past studies. It …
On The Variability Of Drop Size Distributions Over Areas, A. R. Jameson, M. L. Larsen, A. B. Kostinski
On The Variability Of Drop Size Distributions Over Areas, A. R. Jameson, M. L. Larsen, A. B. Kostinski
Department of Physics Publications
Past studies of the variability of drop size distributions (DSDs) have used moments of the distribution such as the mass-weighted mean drop size as proxies for the entire size distribution. In this study, however, the authors separate the total number of drops Nt from the DSD leaving the probability size distributions (PSDs); that is, DSD = Nt × PSD. The variability of the PSDs are then considered using the frequencies of size [P(D)] values at each different drop diameter P(PD | D) over an ensemble of observations collected using a …
Recent Advancement On The Optical Properties Of Two-Dimensional Molybdenum Disulfide (Mos2) Thin Films, Mingxiao Ye, Dustin Winslow, Dongyan Zhang, Ravindra Pandey, Yoke Khin Yap
Recent Advancement On The Optical Properties Of Two-Dimensional Molybdenum Disulfide (Mos2) Thin Films, Mingxiao Ye, Dustin Winslow, Dongyan Zhang, Ravindra Pandey, Yoke Khin Yap
Department of Physics Publications
The emergence of two-dimensional (2D) materials has led to tremendous interest in the study of graphene and a series of mono- and few-layered transition metal dichalcogenides (TMDCs). Among these TMDCs, the study of molybdenum disulfide (MoS2) has gained increasing attention due to its promising optical, electronic, and optoelectronic properties. Of particular interest is the indirect to direct band-gap transition from bulk and few-layered structures to mono-layered MoS2, respectively. In this review, the study of these properties is summarized. The use of Raman and Photoluminescence (PL) spectroscopy of MoS2 has become a reliable technique for differentiating …
A Comprehensive Laboratory Study On The Immersion Freezing Behavior Of Illite Nx Particles: A Comparison Of 17 Ice Nucleation Measurement Techniques, N. Hiranuma, S. Augustin-Bauditz, H. Bingemer, C. Budke, J. Curtius, A. Danielczok, K. Diehl, K. Dreischmeier, M. Ebert, F. Frank, N. Hoffmann, K. Kandler, A. Kiselev, T. Koop, T. Leisner, O. Möhler, B. Nillius, A. Peckhaus, D. Rose, S. Weinbruch, H. Wex, Y. Boose, P. J. Demott, J. D. Hader, T. C.J. Hill, Z. A. Kanji, G. Kulkarni, E. J.T. Levin, C. S. Mccluskey, M. Murakami, B. J. Murray, D. Niedermeier
A Comprehensive Laboratory Study On The Immersion Freezing Behavior Of Illite Nx Particles: A Comparison Of 17 Ice Nucleation Measurement Techniques, N. Hiranuma, S. Augustin-Bauditz, H. Bingemer, C. Budke, J. Curtius, A. Danielczok, K. Diehl, K. Dreischmeier, M. Ebert, F. Frank, N. Hoffmann, K. Kandler, A. Kiselev, T. Koop, T. Leisner, O. Möhler, B. Nillius, A. Peckhaus, D. Rose, S. Weinbruch, H. Wex, Y. Boose, P. J. Demott, J. D. Hader, T. C.J. Hill, Z. A. Kanji, G. Kulkarni, E. J.T. Levin, C. S. Mccluskey, M. Murakami, B. J. Murray, D. Niedermeier
Michigan Tech Publications
Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which ice crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety of instruments have examined immersion freezing activity of atmospherically relevant ice-nucleating particles. However, an intercomparison of these laboratory results is a difficult task because investigators have used different ice nucleation (IN) measurement methods to produce these results. A remaining challenge is to explore the sensitivity and accuracy of these techniques and to understand how the IN results are potentially influenced or biased by experimental parameters associated with these techniques. …
Intercomparing Different Devices For The Investigation Of Ice Nucleating Particles Using Snomax® As Test Substance, H. Wex, S. Augustin-Bauditz, Y. Boose, C. Budke, J. Curtius, K. Diehl, A. Dreyer, F. Frank, S. Hartmann, N. Hiranuma, E. Jantsch, Z. A. Kanji, A. Kiselev, T. Koop, O. Möhler, D. Niedermeier, B. Nillius, M. Rösch, D. Rose, C. Schmidt, I. Steinke, F. Stratmann
Intercomparing Different Devices For The Investigation Of Ice Nucleating Particles Using Snomax® As Test Substance, H. Wex, S. Augustin-Bauditz, Y. Boose, C. Budke, J. Curtius, K. Diehl, A. Dreyer, F. Frank, S. Hartmann, N. Hiranuma, E. Jantsch, Z. A. Kanji, A. Kiselev, T. Koop, O. Möhler, D. Niedermeier, B. Nillius, M. Rösch, D. Rose, C. Schmidt, I. Steinke, F. Stratmann
Michigan Tech Publications
Seven different instruments and measurement methods were used to examine the immersion freezing of bacterial ice nuclei from Snomax® (hereafter Snomax), a product containing ice-active protein complexes from non-viable Pseudomonas syringae bacteria. The experimental conditions were kept as similar as possible for the different measurements. Of the participating instruments, some examined droplets which had been made from suspensions directly, and the others examined droplets activated on previously generated Snomax particles, with particle diameters of mostly a few hundred nanometers and up to a few micrometers in some cases. Data were obtained in the temperature range from -2 to -38 °C, …