Physical Sciences and Mathematics Commons^™

Swarm Intelligence, A Blackboard Architecture And Local Decision Making For Spacecraft Command, Jeremy Straub

Jeremy Straub

Control of a multi-spacecraft constellation is a topic of significant inquiry, at present. This paper presents and evaluates a command architecture for a multi-spacecraft mission. It combines swarm techniques with a decentralized / local decision making architecture (which uses a set of shared blackboards for coordination) and demonstrates the efficacy of this approach. Under this approach, the Blackboard software architecture is used to facilitate data sharing between craft as part of a resilient hierarchy and the swarm techniques are used to coordinate activity. The paper begins with an overview of prior work on the precursor command technologies and then presents …

Small Satellite Communications Security And Student Learning In The Development Of Ground Station Software, Scott Kerlin, Jeremy Straub, Jacob Huhn, Alexander Lewis

Jeremy Straub

Communications security is gaining importance as small spacecraft include actuator capabilities (i.e., propulsion), payloads which could be misappropriated (i.e., high resolution cameras), and research missions with high value/cost. However, security is limited by capability, interoperability and regulation. Additionally, as the small satellite community becomes more mainstream and diverse, the lack of cheap, limited-to-no configuration, pluggable security modules for small satellites also presents a limit for user adoption of security.

This paper discusses a prospective approach for incorporating robust security into a student-developed ground station created at the University of North Dakota as part of a Computer Science Department senior design …

Using A Constellation Of Cubesats For In-Space Optical 3d Scanning, Jeremy Straub

Jeremy Straub

The assessment of in-space objects is an area of ongoing research. Characterization of resident space objects (RSOs) can be useful for assessing the operating status of operator-affiliated or non-affiliated space assets, identifying unknown objects or gathering additional details for known objects. Under the proposed approach, a ring-like constellation of CubeSats passes around the target (at a distance) collecting imagery. This imagery is then utilized to create a 3D model of the target. This paper considers several key elements of a constellation to perform this type of imaging, including the constellation design and imaging capabilities required and the astrodynamics relevant to …

Global Methane And Nitrous Oxide Emissions From Terrestrial Ecosystems Due To Multiple Environmental Changes, Hanqin Tian, Guangsheng Chen, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Bowen Zhang, Kamaljit Banger, Bo Tao, Shufen Pan, Mingliang Liu, Chi Zhang, Lori Bruhwiler, Steven Wofsy

Chaoqun (Crystal) Lu

Greenhouse gas (GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today, posing serious risks for ecosystem health. Methane (CH4) and nitrous oxide (N2O) are the two most important GHGs after carbon dioxide (CO2), but their regional and global budgets are not well known. In this study, we applied a process-based coupled biogeochemical model to concurrently estimate the magnitude and spatial and temporal patterns of CH4 and N2O fluxes as driven by multiple environmental changes, including climate variability, rising atmospheric CO2, increasing nitrogen deposition, tropospheric ozone pollution, land use change, and nitrogen fertilizer use. The estimated CH4 …

Comparison Of Spatial Association Approaches For Landscape Mapping Of Soil Organic Carbon Stocks, Bradley A. Miller, S. Koszinski, M. Wehrhan, M. Sommer

Bradley A Miller

The distribution of soil organic carbon (SOC) can be variable at small analysis scales, but consideration of its role in regional and global issues demands the mapping of large extents. There are many different strategies for mapping SOC, among which is to model the variables needed to calculate the SOC stock indirectly or to model the SOC stock directly. The purpose of this research is to compare direct and indirect approaches to mapping SOC stocks from rule-based, multiple linear regression models applied at the landscape scale via spatial association. The final products for both strategies are high-resolution maps of SOC …

Mirror Symmetry For Log Calabi-Yau Surfaces I, Mark Gross, Paul Hacking, Sean Keel

Paul Hacking

We give a cononical sythetic construction of the mirror family to pairs (Y,D) where Y is a smooth projective surface and D is an anti-canonical cycle of rational curves. This mirror family is constructed as the spectrum of an explicit algebra structure on a vector space with canonical basis and multiplication rule defined in terms of counts of rational curves on Y meeting D in a single point. The elements of the canonical basis are called theta functions. Their construction depends crucially on the Gromov-Witten theory of the pair (Y,D)

Highly Nonlinear Wave Propagation In Elastic Woodpile Periodic Structures, Panos Kevrekidis

Panos Kevrekidis

In the present work, we experimentally implement, numerically compute with, and theoretically analyze a configuration in the form of a single column woodpile periodic structure. Our main finding is that a Hertzian, locally resonant, woodpile lattice offers a test bed for the formation of genuinely traveling waves composed of a strongly localized solitary wave on top of a small amplitude oscillatory tail. This type of wave, called a nanopteron, is not only motivated theoretically and numerically, but is also visualized experimentally by means of a laser Doppler vibrometer. This system can also be useful for manipulating stress waves at will, …

How Success In A Task Depends On The Skills Level: Two Uncertainty-Based Justifications Of A Semi-Heuristic Rasch Model, Joe Lorkowski, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

The more skills a student acquires, the more successful this student is with the corresponding tasks. Empirical data shows that the success in a task grows as a logistic function of skills; this dependence is known as the Rasch model. In this paper, we provide two uncertainty-based justifications for this model: the first justification provides a simple fuzzy-based intuitive explanation for this model, while the second -- more complex one -- explains the exact quantitative behavior of the corresponding dependence.

Zebra And Quagga Mussel Early-Detection Monitoring In High Risk Oregon Waters 2014, Steve W. Wells, Mark D. Sytsma

Center for Lakes and Reservoirs Publications and Presentations

Zebra and quagga mussels (Dreissena polymorpha and D. rostriformis bugensis, respectively) were not detected by Oregon Department of Fish and Wildlife (ODFW) and Portland State University (PSU) during their early detection sampling in Oregon water bodies during 2014. Six high-risk Oregon water bodies were sampled for planktonic larvae and adult mussels during the August to September period. A total of 37 plankton samples were collected and over 520,000 liters of reservoir/lake water were filtered through 64-μm mesh nets during plankton sample collection. The greatest sampling effort occurred in Emigrant Lake, Lake Billy Chinook, and Prineville Reservoir but sampling also occurred …

Oregon Lake Watch, 2014 Annual Report, Meredith Jordan, Rich Miller, Angela L. Strecker

Center for Lakes and Reservoirs Publications and Presentations

The Oregon Lake Watch (OLW) volunteer monitoring program is now in its second year of operation, continuing its focus on early detection of aquatic invasive species (AIS), with a secondary focus on lake water quality. The aquatic invasive species chosen as Watch List priorities for the OLW are based on the Oregon Department of Agriculture’s Noxious Weed List (Oregon Department of Agriculture Noxious Weed Control Program 2014) as well as professional judgement (more information can be found in Oregon Lake Watch Final Report 2014). This report summarizes the data collected by 15 of 24 OLW volunteers over 2014, across 110 …

Encouraging Greater Student Inquiry Engagement In Science Through Motivational Support By Online Scientist-Mentors, Stephen C. Scogin, Carol L. Stuessy

Faculty Publications

Next Generation Science Standards (NGSS) call for integrating knowledge and practice in learning experiences in K-12 science education. PlantingScience (PS), an ideal curriculum for use as an NGSS model, is a computer-mediated collaborative learning environment intertwining scientific inquiry, classroom instruction, and online mentoring from scientists. With implementation in hundreds of classrooms across the United States, science teachers have noted PS as successful in motivating their students to engage in classroom inquiry investigations. To investigate the role of the online scientist-mentors in motivating students in the PS learning environment, we used self-determination theory (SDT) to guide a multiple case study of …

Who Is At The Forest Restoration Table? Final Report On The Blue Mountains Forest Stewardship Network, Phase 1, Rebecca J. Mclain, Kirsten Wright, Lee Cerveny

Institute for Sustainable Solutions Publications and Presentations

Forest collaboratives have emerged throughout the western U.S. as a governance model to address complex ecological challenges that occur at the landscape scale across multiple landownerships and jurisdictional boundaries. Collaborative groups typically involve multiple parties with diverse interests working together to address complex management challenges. Collaboratives often provide input on or make recommendations about public lands actions and decisions. The Blues Stewardship Project was developed to better understand the size, composition, participation, and diversity of forest collaboratives and to identify organizations that may not currently be represented at the collaborative ‘table.’

The study focuses on five collaborative groups in the …

Compensatory Enlargement Of Ossabaw Miniature Swine Coronary Arteries In Diffuse Atherosclerosis, Jenny Susana Choy, Tong Luo, Yunlong Huo, Thomas Wischgoll, Kyle Schultz, Shawn D. Teague, Michael Sturek, Ghassan S. Kassab

Computer Science and Engineering Faculty Publications

Studies in human and non-human primates have confirmed the compensatory enlargement or positive remodeling (Glagov phenomenon) of coronary vessels in the presence of focal stenosis. To our knowledge, this is the first study to document arterial enlargement in a metabolic syndrome animal model with diffuse coronary artery disease (DCAD) in the absence of severe focal stenosis. Two different groups of Ossabaw miniature pigs were fed a high fat atherogenic diet for 4 months (Group I) and 12 months (Group II), respectively. Group I (6 pigs) underwent contrast enhanced computed tomographic angiography (CCTA) and intravascular ultrasound (IVUS) at baseline and after …

Transitions To Valence-Bond Solid Order In A Honeycomb Lattice Antiferromagnet, Sumiran Pujari, Fabien Alet, Kedar Damle

Physics and Astronomy Faculty Publications

We use quantum Monte Carlo methods to study the ground-state phase diagram of a S=1/2 honeycomb lattice magnet in which a nearest-neighbor antiferromagnetic exchange J (favoring Néel order) competes with two different multispin interaction terms: a six-spin interaction Q₃ that favors columnar valence-bond solid (VBS) order, and a four-spin interaction Q₂ that favors staggered VBS order. For Q₃∼Q₂≫J, we establish that the competition between the two different VBS orders stabilizes Néel order in a large swath of the phase diagram even when J is the smallest energy scale in the …

Ward Identities For Transport In 2+1 Dimensions, Carlos Hoyos, Bom Soo Kim, Yaron Oz

Physics and Astronomy Faculty Publications

We use the Ward identities corresponding to general linear transformations, and derive relations between transport coefficients of (2 + 1)-dimensional systems. Our analysis includes relativistic and Galilean invariant systems, as well as systems without boost invariance such as Lifshitz theories. We consider translation invariant, as well as broken translation invariant cases, and include an external magnetic field. Our results agree with effective theory relations of incompressible Hall fluid, and with holographic calculations in a magnetically charged black hole background.

Optimization-Free Optical Focal Field Engineering Through Reversing The Radiation Pattern From A Uniform Line Source, Yanzhong Yu, Qiwen Zhan

Electro-Optics and Photonics Faculty Publications

A simple and flexible method is presented for the generation of optical focal field with prescribed characteristics. By reversing the field pattern radiated from a uniform line source, for which the electric current is constant along its extent, situated at the focus of a 4Pi focusing system formed by two confocal high-NA objective lenses, the required illumination distribution at the pupil plane for creating optical focal field with desired properties can be obtained. Numerical example shows that an arbitrary length optical needle with extremely high longitudinal polarization purity and consistent transverse size of ~0.36λ over the entire depth of focus …

Van Allen Probes Show That The Inner Radiation Zone Contains No Mev Electrons: Ect/Mageis Data, J. F. Fennell, S. Claudepierre, J. B. Blake, T. P. O'Brien, J. H. Clemmons, D. N. Baker, Harlan E. Spence, Geoffrey Reeves

Physics & Astronomy

Abstract

We present Van Allen Probe observations of electrons in the inner radiation zone. The measurements were made by the Energetic Particle, Composition, and Thermal Plasma/Magnetic Electron Ion Spectrometer (MagEIS) sensors that were designed to measure electrons with the ability to remove unwanted signals from penetrating protons, providing clean measurements. No electrons >900 keV were observed with equatorial fluxes above background (i.e., >0.1 el/(cm² s sr keV)) in the inner zone. The observed fluxes are compared to the AE9 model and CRRES observations. Electron fluxes <200 keV exceeded the AE9 model 50% fluxes and were lower than the higher-energy model fluxes. Phase space density radial profiles for 1.3 ≤ L* < 2.5 had mostly positive gradients except near L*~2.1, where the profiles for μ = 20–30 MeV/G were flat …

On The Use Of Drift Echoes To Characterize On-Orbit Sensor Discrepancies, T. P. O'Brien, S. Claudepierre, M. Looper, J. B. Blake, J. F. Fennell, J. H. Clemmons, J. Roeder, S. G. Kanekal, J. W. Manweiler, D. G. Mitchell, M. Gkioulidou, L. J. Lanzerotti, Harlan E. Spence, Geoffrey Reeves, D. N. Baker

Physics & Astronomy

No abstract provided.

Shock-Induced Prompt Relativistic Electron Acceleration In The Inner Magnetosphere, J. C. Foster, J. R. Wygant, M. K. Hudson, A. J. Boyd, D. N. Baker, P. J. Erickson, Harlan E. Spence

Physics & Astronomy

Abstract

We present twin Van Allen Probes spacecraft observations of the effects of a solar wind shock impacting the magnetosphere on 8 October 2013. The event provides details both of the accelerating electric fields associated with the shock and the response of inner magnetosphere electron populations across a broad range of energies. During this period, the two Van Allen Probes observed shock effects from the vantage point of the dayside magnetosphere at radial positions of L = 3 and L = 5, at the location where shock-induced acceleration of relativistic electrons occurs. The extended (~1 min) duration of the accelerating …

Transport In Thin Insulating Films Close To The Boson-Fermion Crossover, J C. Joy, X Zhang, Shawna M. Hollen, C Zhao, G. E. Fernandes, J. M. Xu, J M. Valles Jr.

Physics & Astronomy

No abstract provided.

Scanning Tunneling Microscopy Studies Of Graphene And Hydrogenated Graphene On Cu, Shawna M. Hollen, G A. Gambrel, S J. Tjung, N M. Santagata, Ezekiel Johnston-Halperin, Jay A. Gupta

Physics & Astronomy

Because of the innate sensitivity of 2D material surfaces, it is increasingly important to understand and characterize surface functionalization and interactions with environmental elements, such as substrate, metallic contacts, and adatoms. We developed a method for reproducible, epitaxial growth of pristine graphene islands on Cu(111) in UHV and use scanning tunneling microscopy and spectroscopy (STM) to study the interaction of these graphene islands with the Cu substrate. Tunneling spectroscopy measurements of the electronic surface states over the graphene islands indicate a lower local work function, decreased coupling to bulk Cu states, and a decreased electron effective mass. Additionally, we developed …

Unambiguous Evaluation Of The Relative Photolysis Rates Of Nitro Indolinyl Protecting Groups Critical For Brain Network Studies, Richard L. Comitz, Yannick P. Ouedraogo, Nasri Nesnas

Chemistry and Chemical Engineering Faculty Publications

Nitrated indolinyl photoprotecting groups are crucial tools extensively used in the study of neuronal signal transduction. Mononitrated photolabile protecting groups have been used effectively, however, recent advances in the introduction of a second nitro group have shown improvement in the photo efficiency of neurotransmitter (agonist) release, albeit, to varying extents, depending on the assessment methods employed. An unambiguous method is discussed based on Nuclear Magnetic Resonance (NMR), which is shown to be an effective technique in the relative overall rate comparison amongst varying nitrated protecting groups. Mononitrated and dinitrated photolabile protecting groups such as CDNIGlu and MNI-Glu are used as …

Characterization Of 3d Voronoi Tessellation Nearest Neighbor Lipid Shells Provides Atomistic Lipid Disruption Profile Of Protein Containing Lipid Membranes, Sara Y. Cheng, Hai Viet Duong, Campbell Compton, Mark W. Vaughn, Hoa Nguyen, Kwan H. Cheng

Physics and Astronomy Faculty Research

Quantifying protein-induced lipid disruptions at the atomistic level is a challenging problem in membrane biophysics. Here we propose a novel 3D Voronoi tessellation nearest-atom-neighbor shell method to classify and characterize lipid domains into discrete concentric lipid shells surrounding membrane proteins in structurally heterogeneous lipid membranes. This method needs only the coordinates of the system and is independent of force fields and simulation conditions. As a proof-of-principle, we use this multiple lipid shell method to analyze the lipid disruption profiles of three simulated membrane systems: phosphatidylcholine, phosphatidylcholine/cholesterol, and beta-amyloid/phosphatidylcholine/cholesterol. We observed different atomic volume disruption mechanisms due to cholesterol and beta-amyloid. …

Tools For Discovering And Archiving The Mobile Web, Frank Mccown Ph.D., Monica Yarbrough, Keith Enlow

Computer Science Faculty Research and Publications

Many websites are adapting their content for users who are accessing the Web using smartphones and tablets. The growth of this Mobile Web has required web archivists to change their practices in order to collect this ephemeral web content. We have created a tool called MobileFinder which can be used to automatically detect mobile pages when given the URL of a desktop web page. We used this tool in an experiment to gauge what techniques popular websites are currently using to expose mobile content, and we incorporated the tool into Heritrix to demonstrate its usefulness to the web archiving community.

Experimental Investigation Of Stochastic Parafoil Guidance Using A Graphics Processing Unit, Nathan Slegers, Andrew Brown, Jonathan Rogers

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Control of autonomous systems subject to stochastic uncertainty is a challenging task. In guided airdrop applications, random wind disturbances play a crucial role in determining landing accuracy and terrain avoidance. This paper describes a stochastic parafoil guidance system which couples uncertainty propagation with optimal control to protect against wind and parameter uncertainty in the presence of impact area obstacles. The algorithm uses real-time Monte Carlo simulation performed on a graphics processing unit (GPU) to evaluate robustness of candidate trajectories in terms of delivery accuracy, obstacle avoidance, and other considerations. Building upon prior theoretical developments, this paper explores performance of the …

Discrete Excitation Spectrum Of A Classical Harmonic Oscillator In Zero-Point Radiation, Wayne Cheng-Wei Huang, Herman Batelaan

Department of Physics and Astronomy: Faculty Publications

We report that upon excitation by a single pulse, a classical harmonic oscillator immersed in the classical electromagnetic zero-point radiation exhibits a discrete harmonic spectrum in agreement with that of its quantum counterpart. This result is interesting in view of the fact that the vacuum field is needed in the classical calculation to obtain the agreement.

Investigation Of Electromagnetic Velocities And Negative Refraction In A Chiral Metamaterial With Second-Order Material Dispersion Using Spectral Analyses And Dispersive Models, Monish Ranjan Chatterjee, Tarig A. Algadey

Electrical and Computer Engineering Faculty Publications

In recent years, considerable research has been carried out relative to the electromagnetic (EM) propagation and refraction characteristics in metamaterials with emphasis on the origins of negative refractive index.

Negative refractive index may be introduced in metamaterials via different methods; one such is the condition whereby the Poynting vector of the EM wave is in opposition to the group velocity in the material. Alternatively, negative refractive index also occurs when the group and phase velocities in the medium are in opposition. The latter phenomenon has been extensively investigated in the literature, including recent work involving chiral metamaterials with material dispersion …

Video-To-Video Pose And Expression Invariant Face Recognition Using Volumetric Directional Pattern, Vijayan K. Asari, Almabrok Essa

Electrical and Computer Engineering Faculty Publications

Face recognition in video has attracted attention as a cryptic method of human identification in surveillance systems. In this paper, we propose an end-to-end video face recognition system, addressing a difficult problem of identifying human faces in video due to the presence of large variations in facial pose and expression, and poor video resolution. The proposed descriptor, named Volumetric Directional Pattern (VDP), is an oriented and multi-scale volumetric descriptor that is able to extract and fuse the information of multi frames, temporal (dynamic) information, and multiple poses and expressions of faces in input video to produce feature vectors, which are …

3d Dynamics Of Freshwater Lenses In The Near-Surface Layer Of The Tropical Ocean, Alexander Soloviev, Cayla Whitney Dean, Atsushi Fujimura

Marine & Environmental Sciences Faculty Articles

Convective rains in the Intertropical Convergence Zone produce lenses of freshened water on the ocean surface. Due to significant density differences between the freshened and saltier seawater, strong pressure gradients develop, resulting in lateral spreading of freshwater lenses in the form of gravity currents. Gravity currents inherently involve three-dimensional dynamics. As a type of organized structure, gravity currents may also interact with, and be shaped by, the ambient oceanic and atmospheric environment. Among the important environmental factors are background stratification and wind stress. Under certain conditions, a resonant interaction between a propagating freshwater lens and internal waves in the underlying …

Dihydrolipoic Acid Conjugated Carbon Dots Accelerate Human Insulin Fibrillation, Sheba J. Kuruvilla, Shanghao Li, Lorenzo Sansalone, Blake Fortes, Ian Zheng, Patricia Blackwelder, Cyrus Pumilia, Miodrag Micic, Jhony Orbulescu, Roger M. Leblanc

Marine & Environmental Sciences Faculty Articles

Protein fibrillation is believed to play an important role in the pathology and development of several human diseases, such as Alzheimer’s disease, Parkinson’s disease and type 2 diabetes. Carbon dots (CDs), as a new type of nanoparticle have recently been extensively studied for potential biological applications, but their effects on protein fibrillation remain unexplored. In reality, any application in biological systems will inevitably have “contact” between proteins and CDs. In this study, human insulin was selected as a model protein to study the effects of CDs on protein fibrillation, as proteins may share a common mechanism to form fibrils. Hydrophobic …