Digital Commons Network^™

Rf Energy Harvesting Wireless Communication: Rf Environment, Device Hardware And Practical Issues, Yu Luo, Lina Pu, Guodong Wang, Yanxiao Zhao

Faculty Publications

Radio frequency (RF) based wireless power transfer provides an attractive solution to extend the lifetime of power-constrained wireless sensor networks. Through harvesting RF energy from surrounding environments or dedicated energy sources, low-power wireless devices can be self-sustaining and environment-friendly. These features make the RF energy harvesting wireless communication (RF-EHWC) technique attractive to a wide range of applications. The objective of this article is to investigate the latest research activities on the practical RF-EHWC design. The distribution of RF energy in the real environment, the hardware design of RF-EHWC devices and the practical issues in the implementation of RF-EHWC networks are …

Quenching Estimates For A Non-Newtonian Filtration Equation With Singular Boundary Conditions, Matthew Beauregard, Burhan Selcuk

Faculty Publications

In this paper, the quenching behavior of the non-Newtonian filtration equation (φ(u))t = (|ux| r−2 ux)x with singular boundary conditions, ux (0, t) = u −p (0, t), ux (a, t) = (1 − u(a, t))−q is investigated. Various conditions on the initial condition are shown to guarantee quenching at either the left or right boundary. Theoretical quenching rates and lower bounds to the quenching time are determined when φ(u) = u and r = 2. Numerical experiments are provided to illustrate and provide additional validation of the theoretical estimates to the quenching rates and times.

Wide-Ranging Temporal Variation In Transoceanic Movement And Population Mixing Of Bluefin Tuna In The North Atlantic Ocean, Michael A. Dance

Faculty Publications

Uncertainty regarding the movement and population exchange of Atlantic bluefin tuna (Thunnus thynnus) from the two primary spawning areas (Gulf of Mexico, Mediterranean Sea) is increasingly implicated as a major impediment for the conservation of this species. Here, two mixture methods were applied to natural chemical markers (delta O-18 and delta C-13) in otoliths (ear stones) to comprehensively investigate the nature and degree of transoceanic movement and mixing of eastern and western populations in several areas of the North Atlantic Ocean that potentially represent mixing hotspots. Areas investigated occurred on both sides of the 45 degrees W management boundary as …

New Constraints On Early-Type Galaxy Assembly From Spectroscopic Metallicities Of Globular Clusters In M87, Alexa Villaume, Aaron Romanowsky, Jean Brodie, Jay Strader

Faculty Publications

The observed characteristics of globular cluster (GC) systems, such as metallicity distributions, are commonly used to place constraints on galaxy formation models. However, obtaining reliable metallicity values is particularly difficult because of our limited means to obtain high quality spectroscopy of extragalactic GCs. Often, "color–metallicity relations" are invoked to convert easier-to-obtain photometric measurements into metallicities, but there is no consensus on what form these relations should take. In this paper we make use of multiple photometric data sets and iron metallicity values derived from applying full-spectrum stellar population synthesis models to deep Keck/LRIS spectra of 177 GCs centrally located around …

The Roussopoulos And Schwinger Functionals For Nuclear Systems Involving Imprecisely Known Fluxes And Parameters: Distinctions And Equivalences, Dan Gabriel Cacuci

Faculty Publications

For over 60 years, the Roussopoulos and Schwinger functionals have been used in many works and textbooks under the assumption that they provide “second-order accurate” trial functions for the forward and adjoint fluxes when computing reaction rates and/or particle detector responses in source-driven nuclear systems. The Schwinger functional has been employed as a particularly useful form of the Roussopoulos functional for systems in which the forward and adjoint particle fluxes were normalized. When using these functionals, however, the expressions for the approximate fluxes were postulated arbitrarily while the system parameters were unrealistically assumed to be perfectly well known. This work …

Personalized Product Evaluation Based On Gra-Topsis And Kansei Engineering, Huafeng Quan, Shaobo Li, Hongjing Wei, Jianjun Hu

Faculty Publications

With the improvement of human living standards, users’ requirements have changed from function to emotion. Helping users pick out the most suitable product based on their subjective requirements is of great importance for enterprises. This paper proposes a Kansei engineering-based grey relational analysis and techniques for order preference by similarity to ideal solution (KE-GAR-TOPSIS) method to make a subjective user personalized ranking of alternative products. The KE-GRA-TOPSIS method integrates five methods, including Kansei Engineering (KE), analytic hierarchy process (AHP), entropy, game theory, and grey relational analysis-TOPSIS (GRA-TOPSIS). First, an evaluation system is established by KE and AHP. Second, we define …

Entrna: A Framework To Predict Rna Foldability, Congzhe Su, Jeffery D. Weir, Fei Zhang, Hao Yan, Teresa Wu

Faculty Publications

RNA molecules play many crucial roles in living systems. The spatial complexity that exists in RNA structures determines their cellular functions. Therefore, understanding RNA folding conformations, in particular, RNA secondary structures, is critical for elucidating biological functions. Existing literature has focused on RNA design as either an RNA structure prediction problem or an RNA inverse folding problem where free energy has played a key role.

Towards Lakosian Multilingual Software Design Principles, Damian Lyons, Saba Zahra, Thomas Marshall

Faculty Publications

Large software systems often comprise programs written in different programming languages. In the case when cross-language interoperability is accomplished with a Foreign Function Interface (FFI), for example pybind11, Boost.Python, Emscripten, PyV8, or JNI, among many others, common software engineering tools, such as call-graph analysis, are obstructed by the opacity of the FFI. This complicates debugging and fosters potential inefficiency and security problems. One contributing issue is that there is little rigorous software design advice for multilingual software. In this paper, we present our progress towards a more rigorous design approach to multilingual software. The approach is based on the existing …

Improving Prediction Accuracy In Building Performance Models Using Generative Adversarial Networks (Gans), Chanachok Chokwitthaya, Edward Collier, Yimin Zhu, Supratik Mukhopadhyay

Faculty Publications

Building performance discrepancies between building design and operation are one of the causes that lead many new designs fail to achieve their goals and objectives. A main factor contributing to the discrepancy is occupant behaviors. Occupants responding to a new design are influenced by several factors. Existing building performance models (BPMs) ignore or partially address those factors (called contextual factors) while developing BPMs. To potentially reduce the discrepancies and improve the prediction accuracy of BPMs, this paper proposes a computational framework for learning mixture models by using Generative Adversarial Networks (GANs) that appropriately combining existing BPMs with knowledge on occupant …

Improving Route Choice Models By Incorporating Contextual Factors Via Knowledge Distillation, Qun Liu, Supratik Mukhopadhyay, Yimin Zhu, Ravindra Gudishala, Sanaz Saeidi, Alimire Nabijiang

Faculty Publications

Route Choice Models predict the route choices of travelers traversing an urban area. Most of the route choice models link route characteristics of alternative routes to those chosen by the drivers. The models play an important role in prediction of traffic levels on different routes and thus assist in development of efficient traffic management strategies that result in minimizing traffic delay and maximizing effective utilization of transport system. High fidelity route choice models are required to predict traffic levels with higher accuracy. Existing route choice models do not take into account dynamic contextual conditions such as the occurrence of an …

The Case For Doing Nothing About Institutional Investors' Common Ownership Of Small Stakes In Competing Firms, Thomas A. Lambert, Michael E. Sykuta

Faculty Publications

Recent empirical research purports to demonstrate that institutional investors' "common ownership " of small stakes in competing firms causes those firms to compete less aggressively, injuring consumers. A number of prominent antitrust scholars have cited this research as grounds for limiting the degree to which institutional investors may hold stakes in multiple firms that compete in any concentrated market. This Article contends that the purported competitive problem is overblown and that the proposed solutions would reduce overall social welfare. With respect to the purported problem, we show that the theory of anti-competitive harm from institutional investors' common ownership is implausible …

Theory And The Scholarship Of Teaching And Learning: Inquiry And Practice With Intention, Nancy L. Chick

Faculty Publications

Theory in the scholarship of teaching and learning (SoTL) is the conceptual basis for the practice of SoTL—or, more precisely, the conceptual bases for the practices of SoTL—as well as the bodies of knowledge, methodological assumptions, and explanations of phenomena that are deployed (explicitly or implicitly) from a range of contexts within SoTL. Put another way, theory is thinking on a meta level, a metacognitive move in which practitioners become aware, critical, and intentional of how and why they are doing their practice. It involves taking stock of the existing conversations to move beyond definitions, to critically evaluate gaps and …

Entropy Bound For The Classical Capacity Of A Quantum Channel Assisted By Classical Feedback, Dawei Ding, Yihui Quek, Peter W. Shor, Mark M. Wilde

Faculty Publications

We prove that the classical capacity of an arbitrary quantum channel assisted by a free classical feedback channel is bounded from above by the maximum average output entropy of the quantum channel. As a consequence of this bound, we conclude that a classical feedback channel does not improve the classical capacity of a quantum erasure channel, and by taking into account energy constraints, we conclude the same for a pure-loss bosonic channel. The method for establishing the aforementioned entropy bound involves identifying an information measure having two key properties: 1) it does not increase under a one-way local operations and …

Numerical Convergence Of Finite Difference Approximations For State Based Peridynamic Fracture Models, Prashant K. Jha, Robert Lipton

Faculty Publications

In this work, we study the finite difference approximation for a class of nonlocal fracture models. The nonlocal model is initially elastic but beyond a critical strain the material softens with increasing strain. This model is formulated as a state-based peridynamic model using two potentials: one associated with hydrostatic strain and the other associated with tensile strain. We show that the dynamic evolution is well-posed in the space of Hölder continuous functions C 0,γ with Hölder exponent γ∈(0,1]. Here the length scale of nonlocality is ϵ, the size of time step is Δt and the mesh size is h. The …

Output Feedback Stabilization By Reduced Order Finite Time Observers Using A Trajectory Based Approach, Michael Malisoff, Frederic Mazenc, Saeed Ahmed

Faculty Publications

We use finite time reduced order continuous-discrete observers to solve an output feedback stabilization problem for a class of nonlinear time-varying systems whose outputs contain uncertainty. Unlike earlier works, our feedback is discontinuous, but it does not contain distributed control terms. Our trajectory based approach is based on a contrac-tivity condition. We illustrate our control in the context of a tracking problem for nonholonomic systems in chained form.

On Average Values Of Time-Varying Delays And A New Representation Of Systems With Time-Varying Delays, Frederic Mazenc, Michael Malisoff

Faculty Publications

We show by a counterexample that the asymptotic stability of a system with a pointwise periodic time-varying delay cannot be deduced from the average value of the delay. We use this counterexample to motivate our new representation of systems with time-varying delays, which we use to develop a new state feedback stabilization method.

Sequential Predictors Under Time-Varying Feedback And Measurement Delays And Sampling, Jerome Weston, Michael Malisoff

Faculty Publications

We build sequential predictors for time-varying linear systems with time-varying input delays, outputs, sampling in the control, and time-varying measurement delays. We prove global exponential stability and robustness properties. We allow the sup norm of the input delay to be arbitrarily large and aperiodic sampling. We use a new set of dynamical extensions that contain output measurements, and whose advantages over existing methods include their lack of distributed terms.

High-Harmonic Spectroscopy Of Transient Two-Center Interference Calculated With Time-Dependent Density-Functional Theory, Francois Mauger, Paul M. Abanador, Kenneth Lopata, Kenneth J. Schafer

Faculty Publications

We demonstrate high-harmonic spectroscopy in many-electron molecules using time-dependent density-functional theory. We show that a weak attosecond-pulse-train ionization seed that is properly synchronized with the strong driving mid-infrared laser field can produce experimentally relevant high-harmonic generation (HHG) signals, from which we extract both the spectral amplitude and the target-specific phase (group delay). We also show that further processing of the HHG signal can be used to achieve molecular-frame resolution, i.e., to resolve the contributions from rescattering on different sides of an oriented molecule. In this framework, we investigate transient two-center interference in CO2 and OCS, and how subcycle polarization effects …

Characterizing Diameter Distributions For Uneven-Aged Pine-Oak Mixed Forests In The Qinling Mountains Of China, Shuaichao Sun, Quang V. Cao, Tianjian Cao

Faculty Publications

Pine-oak mixed forests in the Qinling Mountains are an essential part of the ecosystem in Northwestern China. Diameter distribution models for four species groups of pine-oak mixed forests were developed using the Weibull function. Both moment and hybrid estimation approaches were used to predict theWeibull parameters. For each approach, three fitting methods (maximum likelihood estimator regression (MLER), cumulative distribution function regression (CDFR) and modified CDFR) were employed to obtain estimates for coefficients of regression equations to predict Weibull parameters. Overall results indicated that the Moment Estimation approach was better than the Hybrid approach, and that the CDFR method was superior …

Critical Operating Stress Of Persistent Slip Bands In Cu, M. Dodaran, M. M. Khonsari, S. Shao

Faculty Publications

This work elucidates the dependence of operating stress of persistent slip bands (PSB) on the channel width and wall dislocation density. Using Cu as a model system and molecular dynamics as the main investigative tool, a new length scale effect, namely the wall dislocation spacing, is provided to enhance theoretical understanding of PSBs. It is discovered that the operation of PSB is a thermally activated event in which operating stress is inversely related to the wall dislocation spacing, strain rate and temperature. Leveraging the existing framework of confined layer slip in nanoscale metallic multilayers and classical nucleation theory, a mathematical …

Incentive Mechanisms And Impacts Of Negotiation Power And Information Availability In Multi-Relay Cooperative Wireless Networks, Nanmiao Wu, Xiangwei Zhou, Mingxuan Sun

Faculty Publications

Cooperative relaying is highly affected by the way that the source and relays are incentivized. However, the existing studies have not paid enough attention to the impacts of negotiation power and information availability of the players on the network performance. In this paper, two incentive mechanisms for cooperative relaying are first proposed to explore the influence of negotiation power, wherein the source holds either strong or weak negotiation power. In these two cases, the source posts take-it-or-leave-it offers for the relays and has to negotiate possible deals with the relays, respectively. The relay selection rules and the optimal amounts of …

The Molecular Biogeography Of The Indo-Pacific: Testing Hypotheses With Multispecies Genetic Patterns, Eric D. Crandall, Cynthia Riginos, Chris E. Bird, Libby Liggins, Eric Treml, Maria Beger, Paul H. Barber, Sean R. Connolly, Peter F. Cowman, Joseph D. Dibattista, Jeff A. Eble, Sharon F. Magnuson, John B. Horne, Marc Kochzius, Harilaos A. Lessios, Shang Yin Vanson Liu, William B. Ludt, Hawis Madduppa, John M. Pandolfi, Robert J. Toonen, Michelle R. Gaither

Faculty Publications

Aim: To test hypothesized biogeographic partitions of the tropical Indo-Pacific Ocean with phylogeographic data from 56 taxa, and to evaluate the strength and nature of barriers emerging from this test.

>Location: The Indo-Pacific Ocean.

Time Period: Pliocene through the Holocene.

Major Taxa Studied: Fifty-six marine species.

Methods: We tested eight biogeographic hypotheses for partitioning of the Indo-Pacific using a novel modification to analysis of molecular variance. Putative barriers to gene flow emerging from this analysis were evaluated for pairwise Φ_ST, and these Φ_ST distributions were compared to distributions from randomized datasets and …

Tests Of General Relativity With Gw170817, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due …

Nuclear Engineering At The Air Force Institute Of Technology: A Unique Graduate School Experience For A Unique Set Of Students, Michael B. Shattan

Faculty Publications

In August 2018, the Air University Commander formed a task force to review the Air Force’s Science, Technology, Engineering, and Mathematics (STEM) graduate education programs that are delivered and administered through the Air Force Institute of Technology (AFIT). The study was rooted in strategies to support the 2018 National Defense Strategy, and provided the necessary technologically equipped personnel for the 21st century. The study was commonly referred to as “reimagining AFIT”. Several themes emerged from the study, which include reaching a broader community of Airmen through alternate educational modes (e.g. distance learning, short course etc.), forming strategic educational and research …

M2 Factor Of A Vector Schell-Model Beam, Milo W. Hyde Iv, Mark F. Spencer

Faculty Publications

Extending existing scalar Schell-model source work, we derive the M² factor for a general electromagnetic or vector Schell-model source to assess beam quality. In particular, we compute the M² factors for two vector Schell-model sources found in the literature. We then describe how to synthesize vector Schell-model beams in terms of specified, desired M² and present Monte Carlo simulation results to validate our analysis.

A Sustained Ocean Observing System In The Indian Ocean For Climate Related Scientific Knowledge And Societal Needs, J.C. Hermes, Y. Masumoto, L.M. Beal, M.K. Roxy, J. Vialard, M. Andres, H. Annamalai, S. Behera, N. D'Adamo, T. Doi, M. Feng, W. Han, N. Hardman-Mountford, H. Hendon, R. Hood, S. Kido, C. Lee, T. Lee, M. Lengaigne, J. Li, R. Lumpkin, K.N. Navaneeth, B. Milligan, M.J. Mcphaden, M. Ravichandran, T. Shinoda, A. Singh, B. Sloyan, P.G. Strutton, A.C. Subramanian, S. Thurston, T. Tozuka, C.C. Ummenhofer, A.S. Unnikrishnan, R. Venkatesan, D. Wang, J. Wiggert, L. Yu, W. Yu

Faculty Publications

The Indian Ocean is warming faster than any of the global oceans and its climate is uniquely driven by the presence of a landmass at low latitudes, which causes monsoonal winds and reversing currents. The food, water, and energy security in the Indian Ocean rim countries and islands are intrinsically tied to its climate, with marine environmental goods and services, as well as trade within the basin, underpinning their economies. Hence, there are a range of societal needs for Indian Ocean observation arising from the influence of regional phenomena and climate change on, for instance, marine ecosystems, monsoon rains, and …

Narrow-Band Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques that assume the continuous wave to be phase locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in the case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while coherently integrating the entire dataset. In …

Narrow-Band Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Arène, N. Arnaud

Faculty Publications

Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques that assume the continuous wave to be phase locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in the case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while coherently integrating the entire dataset. In …

Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015–2017 Ligo Data, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

We present a search for gravitational waves from 222 pulsars with rotation frequencies 10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015–2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsar's rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = …

Beyond Static Benchmarking: Using Experimental Manipulations To Evaluate Land Model Assumptions, William R. Wieder, David M. Lawrence, Rosie A. Fisher, Gordon B. Bonan, Susan J. Cheng, Christine L. Goodale, A. Stuart Grandy, Charles D. Koven, Danica L. Lombardozzi, Keith W. Oleson, R. Quinn Thomas

Faculty Publications

Land models are often used to simulate terrestrial responses to future environmental changes, but these models are not commonly evaluated with data from experimental manipulations. Results from experimental manipulations can identify and evaluate model assumptions that are consistent with appropriate ecosystem responses to future environmental change. We conducted simulations using three coupled carbon-nitrogen versions of the Community Land Model (CLM, versions 4, 4.5, and—the newly developed—5), and compared the simulated response to nitrogen (N) and atmospheric carbon dioxide (CO2) enrichment with meta-analyses of observations from similar experimental manipulations. In control simulations, successive versions of CLM showed a poleward increase in …