Physical Sciences and Mathematics Commons^™

Nucleation At The Contact Line Observed On Nanotextured Surfaces, C W. Gurganus, J. C. Charnawskas, A. B. Kostinski, R. A. Shaw

Department of Physics Publications

It has been conjectured that roughness plays a role in surface nucleation, the tendency for freezing to begin preferentially at the liquid-gas interface. Using high speed imaging, we sought evidence for freezing at the contact line on catalyst substrates with imposed characteristic length scales (texture). Length scales consistent with the critical nucleus size and with δ∼τ/σ, where τ is a relevant line tension and σ is the surface tension, range from nanometers to micrometers. It is found that nanoscale texture causes a shift in the nucleation of ice in supercooled water to the three-phase contact line, while microscale texture does …

Light Transport In Pt-Invariant Photonic Structures With Hidden Symmetries, M. H. Teimourpour, Ramy El-Ganainy, A. Eisfeld, A. Szameit, Demetrios N. Christodoulides

Department of Physics Publications

We introduce a recursive bosonic quantization technique for generating classical PT photonic structures that possess hidden symmetries and higher order exceptional points. We study light transport in these geometries and we demonstrate that perfect state transfer is possible only for certain initial conditions. Moreover, we show that for the same propagation direction, left and right coherent transports are not symmetric with field amplitudes following two different trajectories. A general scheme for identifying the conservation laws in such PT-symmetric photonic networks is also presented.

The Immersion Mode Ice Nucleation Behavior Of Mineral Dusts: A Comparison Of Different Pure And Surface Modified Dusts, S. Augustin-Bauditz, H. Wex, S. Kanter, M. Ebert, D. Niedermeier, F. Stolz, A. Prager, F. Stratmann

Michigan Tech Publications

In this study we present results from immersion freezing experiments with size-segregated mineral dust particles. Besides two already existing data sets for Arizona Test Dust (ATD), and Fluka kaolinite, we show two new data sets for illite-NX, which consists mainly of illite, a clay mineral, and feldspar, a common crustal material. The experiments were carried out with the Leipzig Aerosol Cloud Interaction Simulator. After comparing the different dust samples, it became obvious that the freezing ability was positively correlated with the K-feldspar content. Furthermore, a comparison of the composition of the ATD, illite-NX, and feldspar samples suggests that within the …

Further Evidence For Superterminal Raindrops, M. L. Larsen, A. Kostinski, A. R. Jameson

Department of Physics Publications

A network of optical disdrometers (including laser precipitation monitors and a two‐dimensional video disdrometer) was utilized to determine whether the recent reports of “superterminal” raindrops were spurious results of drop breakup occurring on instrumentation. Results unequivocally show that superterminal raindrops at small (less than 1 mm) sizes are ubiquitous, are measurable over an extended area, and appear in every rain event investigated. No evidence was found to suggest that superterminal drops are the result of drop breakup due to impact with the measurement instrument; thus, if the superterminal drops are the result of drop fragmentation, this fragmentation happens in the …

Boron Nitride Nanotubes For Spintronics, Kamal B. Dhungana, Ranjit Pati

Department of Physics Publications

With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed …

Laboratory Measurements Of Contact Freezing By Dust And Bacteria At Temperatures Of Mixed-Phase Clouds, Joseph Niehaus, John Becker, Alexander Kostinski, Will Cantrell

Department of Physics Publications

Laboratory measurements of freezing by aerosol particles in contact mode are presented. The fraction of particles catalyzing freezing is quantified for three mineral dusts and three strains of bacteria. This is the most comprehensive such dataset to date for temperatures greater than −20°C, relevant for warm, mixed-phase clouds. For Arizona Test Dust, feldspar, or rhyolitic ash, more than 10³ particles are required to initiate a freezing event at −20°C in the contact mode. At −15°C, more than 10⁵ particles are required. An ice-negative strain of Pseudomonas fluorescens is an order of magnitude more effective than the mineral dusts …

Spatial Patterns Of Record-Setting Temperatures, Alexander Kostinski, Amalia Anserson

Department of Physics Publications

We employ record-breaking statistics to study spatial correlations of record-setting terrestrial surface temperatures. To that end, a simple diagnostic tool is devised, reminiscent of a pair-correlation function. Data analysis reveals that while during the hottest years, record-breaking temperatures arrive in “heat waves”, extending throughout almost the entire continental United States, this is not so for all years, not even recently. Record-breaking temperatures generally exhibit spatial patterns and variability quite different from those of the mean temperatures.

Exceptional Points And Lasing Self-Termination In Photonic Molecules, Ramy El-Ganainy, M. Khajavikhan, Li Ge

Department of Physics Publications

We investigate the rich physics of photonic molecule lasers using a non-Hermitian dimer model.We show that several interesting features, predicted recently using a rigorous steady-state ab initio laser theory (SALT), can be captured by this toy model. In particular, we demonstrate the central role played by exceptional points (EPs) in both pump-selective lasing and laser self-termination phenomena. Due to its transparent mathematical structure, our model provides a lucid understanding for how different physical parameters (optical loss, modal coupling between microcavities, and pump profiles) affect the lasing action. Interestingly, our analysis also confirms that, for frequency mismatched cavities, operation in the …

Giant Amplification Of Tunnel Magnetoresistance In A Molecular Junction: Molecularspin-Valve Transistor, Kamal B. Dhungana, Ranjit Pati

Department of Physics Publications

Amplification of tunnel magnetoresistance by gate field in a molecular junction is the most important requirement for the development of a molecular spin valve transistor. Herein, we predict a giant amplification of tunnel magnetoresistance in a single molecular spin valve junction, which consists of Ru-bis-terpyridine molecule as a spacer between two ferromagnetic nickelcontacts. Based on the first-principles quantum transport approach, we show that a modest change in the gate field that is experimentally accessible can lead to a substantial amplification (320%) of tunnel magnetoresistance. The origin of such large amplification is attributed to the spin dependent modification of orbitals at …

Supersymmetric Mode Converters, Matthias Heinrich, Mohammad-Ali Miri, Simon Stützer, Ramy El-Ganainy, Stefan Nolte, Alexander Szameit, Demetrios N. Christodoulides

Department of Physics Publications

Originally developed in the context of quantum field theory, the concept of supersymmetry can be used to systematically design a new class of optical structures. In this work, we demonstrate how key features arising from optical supersymmetry can be exploited to control the flow of light for mode division multiplexing applications. Superpartner configurations are experimentally realized in coupled optical networks, and the corresponding light dynamics in such systems are directly observed. We show that supersymmetry can be judiciously utilized to remove the fundamental mode of a multimode optical structure, while establishing global phase matching conditions for the remaining set of …

A Semi-Lagrangian View Of Ozone Production Tendency In North American Outflow In The Summers Of 2009 And 2010, B. Zhang, R. C. Owen, J A Perlinger, A. Kumar, S. Wu, M. Val Martin, L. Kramer, D. Helmig, R. E. Honrath

Michigan Tech Publications

The Pico Mountain Observatory, located at 2225 m a.s.l. in the Azores Islands, was established in 2001 to observe long-range transport from North America to the central North Atlantic. In previous research conducted at the observatory, ozone enhancement (> 55 ppbv) in North American outflows was observed, and efficient ozone production in these outflows was postulated. This study is focused on determining the causes for high d[O3] / d[CO] values (~1 ppbv ppbv−1) observed in the summers of 2009 and 2010. The folded retroplume technique, developed by Owen and Honrath (2009), was applied to combine upwind FLEXPART transport …

On-Chip Multi 4-Port Optical Circulators, Ramy El-Ganainy, Miguel Levy

Department of Physics Publications

We present a new geometry for on-chip optical circulators based on waveguide arrays. The optical array is engineered to mimic the Fock space representation of a noninteracting two-site Bose–Hubbard Hamiltonian. By introducing a carefully tailored magnetooptic nonreciprocity to these structures, the array operates in the perfect transfer and surface Bloch oscillation modes in the forward and backward propagation directions, respectively. We show that an array made of ð2N þ 1Þ waveguide channels can function as N 4-port optical circulators with very large isolation ratios and low forward losses. Numerical analysis using beam propagation method indicates a large bandwidth of operation.

A Technique To Measure Ice Nuclei In The Contact Mode, Joseph Niehaus, Kristopher W. Bunker, Swarup China, Alexander Kostinski, Claudio Mazzoleni, Will Cantrell

Department of Physics Publications

This study presents a new technique to study ice nucleation by aerosols in the contact mode. Contact freezing depends upon the interaction of a supercooled droplet of water and an aerosol particle, with the caveat that the particle must be at the air–water interface. To measure nucleation catalyzed in this mode, the technique employs water droplets that are supercooled via a temperature-controlled copper stage, then pulls aerosol-laden air past them. Particles deposit out of the airstream and come into contact with the surface of the droplet. The probability that a particle–droplet collision initiates a freezing event, necessitating knowledge of the …

Comparison Of Computer-Based And Optical Face Recognition Paradigms, Abdulaziz A. Alorf

Dissertations, Master's Theses and Master's Reports - Open

The main objectives of this thesis are to validate an improved principal components analysis (IPCA) algorithm on images; designing and simulating a digital model for image compression, face recognition and image detection by using a principal components analysis (PCA) algorithm and the IPCA algorithm; designing and simulating an optical model for face recognition and object detection by using the joint transform correlator (JTC); establishing detection and recognition thresholds for each model; comparing between the performance of the PCA algorithm and the performance of the IPCA algorithm in compression, recognition and, detection; and comparing between the performance of the digital model …

Quantum Correlations Of Lights In Macroscopic Environments, Yong Meng Sua

Dissertations, Master's Theses and Master's Reports - Open

This dissertation presents a detailed study in exploring quantum correlations of lights in macroscopic environments. We have explored quantum correlations of single photons, weak coherent states, and polarization-correlated/polarization-entangled photons in macroscopic environments. These included macroscopic mirrors, macroscopic photon number, spatially separated observers, noisy photons source and propagation medium with loss or disturbances.

We proposed a measurement scheme for observing quantum correlations and entanglement in the spatial properties of two macroscopic mirrors using single photons spatial compass state. We explored the phase space distribution features of spatial compass states, such as chessboard pattern by using the Wigner function. The displacement and …

Integration Of Instrumentation And Processing Software Of A Laser Speckle Contrast Imaging System, Jacob James Carrick

Dissertations, Master's Theses and Master's Reports - Open

Laser speckle contrast imaging (LSCI) has the potential to be a powerful tool in medicine, but more research in the field is required so it can be used properly. To help in the progression of Michigan Tech's research in the field, a graphical user interface (GUI) was designed in Matlab to control the instrumentation of the experiments as well as process the raw speckle images into contrast images while they are being acquired. The design of the system was successful and is currently being used by Michigan Tech's Biomedical Engineering department. This thesis describes the development of the LSCI GUI …

The Three Dimensional Shape And Roughness Of Mineral Dust, Xinxin Woodward

Dissertations, Master's Theses and Master's Reports - Open

Mineral dust shape and roughness are important for a multitude of processes; it is known for aspherical shape but the true measurements in three dimensions are rare. Atomic Force Microscope was used for determine both 3D shape and roughness for two dust which are commonly used in laboratory experiments – Arizona Test Dust (ATD) and Kaolinite. We determined both of them are rather flat and round; an oblate spheroid would be a good model. Loess Filter was used to smooth the particles' surface and correlation analysis was used to examine the surfaces' properties of the dust; we found no features …

A Theoretical Study Of Interaction Of Nanoparticles With Biomolecule, Chunhui Liu

Dissertations, Master's Theses and Master's Reports - Open

Many types of materials at nanoscale are currently being used in everyday life. The production and use of such products based on engineered nanomaterials have raised concerns of the possible risks and hazards associated with these nanomaterials. In order to evaluate and gain a better understanding of their effects on living organisms, we have performed first-principles quantum mechanical calculations and molecular dynamics simulations. Specifically, we will investigate the interaction of nanomaterials including semiconducting quantum dots and metallic nanoparticles with various biological molecules, such as dopamine, DNA nucleobases and lipid membranes.

Firstly, interactions of semiconducting CdSe/CdS quantum dots (QDs) with the …

Characterization Of The Atmospheric Effects On The Transmission Of Thermal Radiation, Mohamed E. Hanafy

Dissertations, Master's Theses and Master's Reports - Open

Atmospheric scattering plays a crucial rule in degrading the performance of electro optical imaging systems operating in the visible and infra-red spectral bands, and hence limits the quality of the acquired images, either through reduction of contrast or increase of image blur. The exact nature of light scattering by atmospheric media is highly complex and depends on the types, orientations, sizes and distributions of particles constituting these media, as well as wavelengths, polarization states and directions of the propagating radiation. Here we follow the common approach for solving imaging and propagation problems by treating the propagating light through atmospheric media …

Multi-Wavelength Speckle Reduction For Laser Pico-Projectors Using Diffractive Optics, Weston H. Thomas

Dissertations, Master's Theses and Master's Reports - Open

Personal electronic devices, such as cell phones and tablets, continue to decrease in size while the number of features and add-ons keep increasing. One particular feature of great interest is an integrated projector system. Laser pico-projectors have been considered, but the technology has not been developed enough to warrant integration. With new advancements in diode technology and MEMS devices, laser-based projection is currently being advanced for pico-projectors. A primary problem encountered when using a pico-projector is coherent interference known as speckle. Laser speckle can lead to eye irritation and headaches after prolonged viewing. Diffractive optical elements known as diffusers have …