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

Physical Sciences and Mathematics Commons™

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

University of Nevada, Las Vegas

Series

Discipline
Keyword
Publication Year
Publication
File Type

Articles 61 - 90 of 1954

Full-Text Articles in Physical Sciences and Mathematics

How State Interventions Affect Municipalities Taking The Lead In Sustainability, Jayce L. Farmer, Andres J.Rodriguez Lombeida Jun 2021

How State Interventions Affect Municipalities Taking The Lead In Sustainability, Jayce L. Farmer, Andres J.Rodriguez Lombeida

Public Policy and Leadership Faculty Publications

The state and local governments throughout the United States interact within a complex system of multilevel governance to advance sustainability. However, we know little about what this hierarchical system of exchanges means for municipalities as they work to achieve energy efficient government operations. Drawing on a perspective of “contested federalism”, we examine how the transaction costs of state–local government relations affect the efforts of U.S. cities to lead by example and promote sustainability within their internal processes. We apply a Bayesian item response theory approach to assess the effects of state-level fiscal and policy interventions on municipal commitments to energy …

Go to article

Bountychain: Toward Decentralizing A Bug Bounty Program With Blockchain And Ipfs, Alex Hoffman, Phillipe Austria, Chol Hyun Park, Yoohwan Kim Jun 2021

Bountychain: Toward Decentralizing A Bug Bounty Program With Blockchain And Ipfs, Alex Hoffman, Phillipe Austria, Chol Hyun Park, Yoohwan Kim

Computer Science Faculty Research

Bug Bounty Programs (BBPs) play an important role in providing and maintaining security in software applications. These programs allow testers to discover and resolve bugs before the general public is aware of them, preventing incidents of widespread abuse. However, they have shown problems such as organizations providing accountability of reporting bugs and nonrecognition of testers. In this paper, we discuss Bountychain, a decentralized application using Ethereum-based Smart Contracts (SCs) and the Interplanetary File System (IPFS), a distributed file storage system. Blockchain and SCs provide a safe, secure and transparent platform for a BBP. Testers can submit bug reports and organizations …

Go to article

Colossal Density-Driven Resistance Response In The Negative Charge Transfer Insulator Mns2, Dylan Durkee, Nathan Dasenbrock-Gammon, G. Alexander Smith, Elliot Snider, Dean Smith, Christian Childs, Simon A.J. Kimber, Keith V. Lawler, Ranga P. Dias, Ashkan Salamat Jun 2021

Colossal Density-Driven Resistance Response In The Negative Charge Transfer Insulator Mns2, Dylan Durkee, Nathan Dasenbrock-Gammon, G. Alexander Smith, Elliot Snider, Dean Smith, Christian Childs, Simon A.J. Kimber, Keith V. Lawler, Ranga P. Dias, Ashkan Salamat

Chemistry and Biochemistry Faculty Research

A reversible density driven insulator to metal to insulator transition in high-spin MnS2 is experimentally observed, leading with a colossal electrical resistance drop of 108 ω by 12 GPa. Density functional theory simulations reveal the metallization to be unexpectedly driven by previously unoccupied S22- σ3p∗ antibonding states crossing the Fermi level. This is a unique variant of the charge transfer insulator to metal transition for negative charge transfer insulators having anions with an unsaturated valence. By 36 GPa the emergence of the low-spin insulating arsenopyrite (P21/c) is confirmed, and the bulk metallicity is broken with the system returning to an …

Go to article

Topology Identification In Distribution System Via Machine Learning Algorithms, Peyman Razmi, Mahdi Ghaemi Asl, Giorgio Canarella, Afsaneh Sadat Emami Jun 2021

Topology Identification In Distribution System Via Machine Learning Algorithms, Peyman Razmi, Mahdi Ghaemi Asl, Giorgio Canarella, Afsaneh Sadat Emami

Economics Faculty Publications

This paper contributes to the literature on topology identification (TI) in distribution networks and, in particular, on change detection in switching devices' status. The lack of measurements in distribution networks compared to transmission networks is a notable challenge. In this paper, we propose an approach to topology identification (TI) of distribution systems based on supervised machine learning (SML) algorithms. This methodology is capable of analyzing the feeder's voltage profile without requiring the utilization of sensors or any other extraneous measurement device. We show that machine learning algorithms can track the voltage profile's behavior in each feeder, detect the status of …

Go to article

Coupled Deep-Mantle Carbon-Water Cycle: Evidence From Lower-Mantle Diamonds, Wenzhong Wang, Oliver Tschauner, Shichun Huang, Zhongqing Wu, Yufei Meng, Hans Bechtel, Ho Kwang Mao May 2021

Coupled Deep-Mantle Carbon-Water Cycle: Evidence From Lower-Mantle Diamonds, Wenzhong Wang, Oliver Tschauner, Shichun Huang, Zhongqing Wu, Yufei Meng, Hans Bechtel, Ho Kwang Mao

Geoscience Faculty Publications

Diamonds form in a variety of environments between subducted crust, lithospheric and deep mantle. Recently, deep source diamonds with inclusions of the high-pressure H O-phase ice-VII were discovered. By correlating the pressures of ice-VII inclusions with those of other high-pressure inclusions, we assess quantitatively the pressures and temperatures of their entrapment. We show that the ice-VII-bearing diamonds formed at depths down to 800 ± 60 km but at temperatures 200–500 K below average mantle temperature that match the pressure-temperature conditions of decomposing dense hydrous mantle silicates. Our work presents strong evidence for coupled recycling of water and carbon in the …

Go to article

Control-Oriented Nonlinear Modeling Of Polyvinyl Chloride (Pvc) Gel Actuators, Mohammed Al-Rubaiai, Xinda Qi, Zachary Frank, Ryohei Tsuruta, Umesh Gandhi, Kwang J. Kim, Xiaobo Tan May 2021

Control-Oriented Nonlinear Modeling Of Polyvinyl Chloride (Pvc) Gel Actuators, Mohammed Al-Rubaiai, Xinda Qi, Zachary Frank, Ryohei Tsuruta, Umesh Gandhi, Kwang J. Kim, Xiaobo Tan

Mechanical Engineering Faculty Research

Polyvinyl chloride (PVC) gel-based actuators are a new class of soft, electroactive polymer actuators with several attractive properties, including low cost, large compliance, large strain output, high-stress output, fast response, and stability against thermal influence. While PVC gel actuators are quickly gaining attention, they remain largely unexplored despite their great potential in a long list of applications compared with many other smart material actuators. In particular, little work has been reported on modeling nonlinear dynamics of PVC actuators. In this work a nonlinear, control-oriented Hammerstein model, with a polynomial nonlinearity preceding a transfer function, is proposed to capture the amplitude-dependent …

Go to article

Cumulative Infiltration And Infiltration Rate Prediction Using Optimized Deep Learning Algorithms: A Study In Western Iran, Mahdi Panahi, Khabat Khosravi, Sajjad Ahmad, Somayeh Panahi, Salim Heddam, Assefa M. Melesse, Ebrahim Omidvar, Chang Wook Lee May 2021

Cumulative Infiltration And Infiltration Rate Prediction Using Optimized Deep Learning Algorithms: A Study In Western Iran, Mahdi Panahi, Khabat Khosravi, Sajjad Ahmad, Somayeh Panahi, Salim Heddam, Assefa M. Melesse, Ebrahim Omidvar, Chang Wook Lee

Civil and Environmental Engineering and Construction Faculty Research

Study region: Sixteen different sites from two provinces (Lorestan and Illam) in the western part of Iran were considered for the field data measurement of cumulative infiltration, infiltration rate, and other effective variables that affect infiltration process. Study focus: Soil infiltration is recognized as a fundamental process of the hydrologic cycle affecting surface runoff, soil erosion, and groundwater recharge. Hence, accurate prediction of the infiltration process is one of the most important tasks in hydrological science. As direct measurement is difficult and costly, and empirical models are inaccurate, the current study proposed a standalone, and optimized deep learning algorithm of …

Go to article

Real-Time Pm10 Emission Rates From Paved Roads By Measurement Of Concentrations In The Vehicle's Wake Using On-Board Sensors Part 2. Comparison Of Scamper, Traker™, Flux Measurements, And Ap-42 Silt Sampling Under Controlled Conditions, Dennis R. Fitz, Kurt Bullimer, Vic Etyemezian, Hampden D. Kuhns, John A. Gillies, George Nikolich, David E. James, Rodney Langston, Russell S. Merle Jr. May 2021

Real-Time Pm10 Emission Rates From Paved Roads By Measurement Of Concentrations In The Vehicle's Wake Using On-Board Sensors Part 2. Comparison Of Scamper, Traker™, Flux Measurements, And Ap-42 Silt Sampling Under Controlled Conditions, Dennis R. Fitz, Kurt Bullimer, Vic Etyemezian, Hampden D. Kuhns, John A. Gillies, George Nikolich, David E. James, Rodney Langston, Russell S. Merle Jr.

Civil and Environmental Engineering and Construction Faculty Research

Representative soil was evenly applied to an 800-m section of road surface. The test area was of sufficient length to allow for measurement at constant speeds of up to 72 km hr−1. SCAMPER and TRAKER™ mobile measurement vehicles made repeated test runs while an instrumented tower measured upwind-downwind horizontal PM10 flux. AP-42 methods were used to collect silt samples and calculate PM10 emission factors. Both silt loadings and vehicle speeds were varied during the experiment. Street sweeping the as-found roadway showed an initial rise in PM10 emission rates. Both TRAKER and SCAMPER measured rapid decay of PM10 emission rates after …

Go to article

Climatic And Topographic Control Of The Stable Isotope Values Of Rivers On The South Island Of New Zealand, Matthew S. Lachniet, Christopher M. Moy, Christina Riesselman, Haroon Stephen, Andrew M. Lorrey May 2021

Climatic And Topographic Control Of The Stable Isotope Values Of Rivers On The South Island Of New Zealand, Matthew S. Lachniet, Christopher M. Moy, Christina Riesselman, Haroon Stephen, Andrew M. Lorrey

Geoscience Faculty Publications

We show that climate and topography control the spatial distribution of stable isotope values on the South Island of New Zealand, based on a spatially dense (n = 193) river isotopic survey. Our data show a δ O minimum in isotope values east of the Southern Alps that demonstrates topographically driven continentality associated with the Southern Alps, which intersect the prevailing, moisture-laden westerlies. Our data define a South Island surface water line of δ H = 8.17 (±0.26) × δ O + 10.57 (±2.04), which is identical within 95% confidence intervals to the global and New Zealand meteoric water lines …

Go to article

Molybdenite Re–Os, Titanite And Garnet U–Pb Dating Of The Magushan Skarn Cu–Mo Deposit, Xuancheng District, Middle–Lower Yangtze River Metallogenic Belt, Yue Li, Feng Yuan, Simon M. Jowitt, Fangyue Wang, Xiangling Li, Yufeng Deng, Yunyue Wang, Taofa Zhou May 2021

Molybdenite Re–Os, Titanite And Garnet U–Pb Dating Of The Magushan Skarn Cu–Mo Deposit, Xuancheng District, Middle–Lower Yangtze River Metallogenic Belt, Yue Li, Feng Yuan, Simon M. Jowitt, Fangyue Wang, Xiangling Li, Yufeng Deng, Yunyue Wang, Taofa Zhou

Geoscience Faculty Publications

© 2020 Elsevier B.V. The Magushan skarn Cu–Mo deposit is a representative example of the skarn mineralization occurring within the Xuancheng ore district of the Middle–Lower Yangtze River Metallogenic Belt of eastern China. The precise age of an ore deposit is important for understanding the timing of mineralization relative to other geological events in a region and to fully place the formation of a mineral deposit within the geological context of other processes that occur within the study area. Here, we present new molybdenite Re–Os and titanite and andradite garnet U–Pb ages for the Magushan deposit and use these data …

Go to article

Experimental Constraint On Axionlike Particles Over Seven Orders Of Magnitude In Mass, Tanya S. Roussy, Daniel A. Palken, William B. Cairncross, Benjamin M. Brubaker, Daniel N. Gresh, Matt Grau, Kevin C. Cossel, Kia Boon Ng, Yuval Shagam, Yan Zhou, Victor V. Flambaum, Konrad W. Lehnert, Jun Ye, Eric A. Cornell Apr 2021

Experimental Constraint On Axionlike Particles Over Seven Orders Of Magnitude In Mass, Tanya S. Roussy, Daniel A. Palken, William B. Cairncross, Benjamin M. Brubaker, Daniel N. Gresh, Matt Grau, Kevin C. Cossel, Kia Boon Ng, Yuval Shagam, Yan Zhou, Victor V. Flambaum, Konrad W. Lehnert, Jun Ye, Eric A. Cornell

Physics & Astronomy Faculty Research

We use our recent electric dipole moment (EDM) measurement data to constrain the possibility that the HfF+ EDM oscillates in time due to interactions with candidate dark matter axionlike particles (ALPs). We employ a Bayesian analysis method which accounts for both the look-elsewhere effect and the uncertainties associated with stochastic density fluctuations in the ALP field. We find no evidence of an oscillating EDM over a range spanning from 27 nHz to 400 mHz, and we use this result to constrain the ALP-gluon coupling over the mass range 10-22-10-15 eV. This is the first laboratory constraint on the ALP-gluon coupling …

Go to article

On The Role Of Resonances In Polluting White Dwarfs By Asteroids, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio, Dimitri Veras Apr 2021

On The Role Of Resonances In Polluting White Dwarfs By Asteroids, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio, Dimitri Veras

Physics & Astronomy Faculty Research

Pollution of white dwarf atmospheres may be caused by asteroids that originate from the locations of secular and mean-motion resonances in planetary systems. Asteroids in these locations experience increased eccentricity, leading to tidal disruption by the white dwarf. We examine how the ν6 secular resonance shifts outwards into a previously stable region of the asteroid belt, as the star evolves to a white dwarf. Analytic secular models require a planet to be engulfed in order to shift the resonance. We show with numerical simulations that as a planet gets engulfed by the evolving star, the secular resonance shifts and the …

Go to article

Equation Of State For Natural Almandine, Spessartine, Pyrope Garnet: Implications For Quartz-In-Garnet Elastic Geobarometry, Suzanne R. Mulligan, Elissaios Stavrou, Stella Chariton, Oliver Tschauner, Ashkan Salamat, Michael Wells, Alexander G. Smith, Thomas D. Hoisch, Vitali Prakapenka Apr 2021

Equation Of State For Natural Almandine, Spessartine, Pyrope Garnet: Implications For Quartz-In-Garnet Elastic Geobarometry, Suzanne R. Mulligan, Elissaios Stavrou, Stella Chariton, Oliver Tschauner, Ashkan Salamat, Michael Wells, Alexander G. Smith, Thomas D. Hoisch, Vitali Prakapenka

Geoscience Faculty Publications

The equation of state (EoS) of a natural almandine74spessartine13pyrope10grossular3 garnet of a typical composition found in metamorphic rocks in Earth’s crust was obtained using single crystal synchrotron X-ray diffraction under isothermal room temperature compression. A third-order Birch-Murnaghan EoS was fitted to P-V data and the results are compared with published EoS for iron, manganese, magnesium, and calcium garnet compositional end-members. This comparison reveals that ideal solid solution mixing can reproduce the EoS for this intermediate composition of garnet. Additionally, this new EoS was used to calculate geobarometry on a garnet sample from the same rock, which was collected from the …

Go to article

A Multiproxy Database Of Western North American Holocene Paleoclimate Records, Cody C. Routson, Darrell S. Kaufman, Nicholas P. Mckay, Michael P. Erb, Stéphanie H. Arcusa, Kendrick J. Brown, Matthew E. Kirby, Jeremiah P. Marsicek, R. Scott Anderson, Gonzalo Jiménez-Moreno, Jessica R. Rodysill, Matthew S. Lachniet, Sherilyn C. Fritz, Joseph R. Bennett, Michelle F. Goman, Sarah E. Metcalfe, Jennifer M. Galloway, Gerrit Schoups, David B. Wahl, Jesse L. Morris, Francisca Staines-Urías, Andria Dawson, Bryan N. Shuman, Daniel G. Gavin, Jeffrey S. Munroe, Brian F. Cumming Apr 2021

A Multiproxy Database Of Western North American Holocene Paleoclimate Records, Cody C. Routson, Darrell S. Kaufman, Nicholas P. Mckay, Michael P. Erb, Stéphanie H. Arcusa, Kendrick J. Brown, Matthew E. Kirby, Jeremiah P. Marsicek, R. Scott Anderson, Gonzalo Jiménez-Moreno, Jessica R. Rodysill, Matthew S. Lachniet, Sherilyn C. Fritz, Joseph R. Bennett, Michelle F. Goman, Sarah E. Metcalfe, Jennifer M. Galloway, Gerrit Schoups, David B. Wahl, Jesse L. Morris, Francisca Staines-Urías, Andria Dawson, Bryan N. Shuman, Daniel G. Gavin, Jeffrey S. Munroe, Brian F. Cumming

Geoscience Faculty Publications

Holocene climate reconstructions are useful for understanding the diverse features and spatial heterogeneity of past and future climate change. Here we present a database of western North American Holocene paleoclimate records. The database gathers paleoclimate time series from 184 terrestrial and marine sites, including 381 individual proxy records. The records span at least 4000 of the last 12 000 years (median duration of 10 725 years) and have been screened for resolution, chronologic control, and climate sensitivity. Records were included that reflect temperature, hydroclimate, or circulation features. The database is shared in the machine readable Linked Paleo Data (LiPD) format …

Go to article

Maximum Temperatures In Evolving Protoplanetary Discs And Composition Of Planetary Building Blocks, Min Li, Shichun Huang, Zhaohuan Zhu, Michael I. Petaev, Jason H. Steffen Mar 2021

Maximum Temperatures In Evolving Protoplanetary Discs And Composition Of Planetary Building Blocks, Min Li, Shichun Huang, Zhaohuan Zhu, Michael I. Petaev, Jason H. Steffen

Geoscience Faculty Publications

The maximum temperature and radial temperature profile in a protoplanetary disc are important for the condensation of different elements in the disc. We simulate the evolution of a set of protoplanetary discs from the collapse of their progenitor molecular cloud cores as well as the dust decoupling within the discs as they evolve. We show how the initial properties of the cloud cores affect the thermal history of the protoplanetary discs using a simple viscous disc model. Our results show that the maximum mid-plane temperature in the disc occurs within 0.5 au. It increases with the initial cloud temperature and …

Go to article

Pressure- And Temperature-Dependent Inelastic Neutron Scattering Study Of The Phase Transition And Phonon Lattice Dynamics In Para-Terphenyl, Qingan Cai, Michael Mcintire, Luke L. Daemen, Chen Li, Eric Chronister Mar 2021

Pressure- And Temperature-Dependent Inelastic Neutron Scattering Study Of The Phase Transition And Phonon Lattice Dynamics In Para-Terphenyl, Qingan Cai, Michael Mcintire, Luke L. Daemen, Chen Li, Eric Chronister

Chemistry and Biochemistry Faculty Research

Inelastic neutron scattering has been performed on para-terphenyl at temperatures from 10 to 200 K and under pressures from the ambient pressure to 1.51 kbar. The temperature dependence of phonons, especially low-frequency librational bands, indicates strong anharmonic phonon dynamics. The pressure- and temperature-dependence of the phonon modes suggest a lack of phase transition in the region of 0-1.51 kbar and 10-30 K. Additionally, the overall lattice dynamics remains similar up to 200 K under the ambient pressure. The results suggest that the boundary between the ordered triclinic phase and the third solid phase, reported at lower temperatures and higher pressures, …

Go to article

Steep Sulfur Gradient In Cztsse Solar Cells By H2s-Assisted Rapid Surface Sulfurization, Teoman Taskesen, Devendra Pareek, Dirk Hauschild, Alan Haertel, Lothar Weinhardt, Wanli Yang, Timo Pfeiffelmann, David Nowak, Clemens Heske, Levent Gütay Mar 2021

Steep Sulfur Gradient In Cztsse Solar Cells By H2s-Assisted Rapid Surface Sulfurization, Teoman Taskesen, Devendra Pareek, Dirk Hauschild, Alan Haertel, Lothar Weinhardt, Wanli Yang, Timo Pfeiffelmann, David Nowak, Clemens Heske, Levent Gütay

Chemistry and Biochemistry Faculty Research

Sulfur/selenium grading is a widely used optimization strategy in kesterite thin-film solar cells to obtain a bandgap-graded absorber material and to optimize optical and electrical properties of the solar-cell device. In this work, we present a novel approach to introduce a [S]/([S] + [Se]) grading for Cu ZnSn(S,Se) solar cells. In contrast to commonly used methods with slow process dynamics, the presented approach aims to create a fast sulfurization reaction on the surface of pure selenide kesterite absorbers by using highly reactive H S gas and high sulfurization temperatures in a rapid flash-type process. With a combination of X-ray photoelectron …

Go to article

Poly(Pyridinium Salt)S Containing 2,7-Diamino-9,9'-Dioctylfluorene Moieties With Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline And Light-Emitting Properties, Pradip K. Bhowmik, Tae S. Jo, Jung J. Koh, Jongwon Park, Bidyut Biswas, Ronald Carlo G. Principe, Haesook Han, András F. Wacha, Matti Knaapila Mar 2021

Poly(Pyridinium Salt)S Containing 2,7-Diamino-9,9'-Dioctylfluorene Moieties With Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline And Light-Emitting Properties, Pradip K. Bhowmik, Tae S. Jo, Jung J. Koh, Jongwon Park, Bidyut Biswas, Ronald Carlo G. Principe, Haesook Han, András F. Wacha, Matti Knaapila

Chemistry and Biochemistry Faculty Research

A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (1H), and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (Mns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12-1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60-80% solvent fraction. A lyotropic smectic phase contains 10 …

Go to article

Mechanical Characteristics Of Cement Paste In The Presence Of Carbon Nanotubes And Silica Oxide Nanoparticles: An Experimental Study, Moses Karakouzian, Visar Farhangi, Marzieh Ramezani Farani, Alireza Joshaghani, Mehdi Zadehmohamad, Mohammad Ahmadzadeh Mar 2021

Mechanical Characteristics Of Cement Paste In The Presence Of Carbon Nanotubes And Silica Oxide Nanoparticles: An Experimental Study, Moses Karakouzian, Visar Farhangi, Marzieh Ramezani Farani, Alireza Joshaghani, Mehdi Zadehmohamad, Mohammad Ahmadzadeh

Civil and Environmental Engineering and Construction Faculty Research

Considering the remarkable characteristics of nanomaterials, previous research studies investigated the effects of incorporating different types of these materials on improving the concrete properties. However, further studies are required to evaluate the complementary hybridization and synergistic influence of nanomaterials. In this research, the combined effect of adding nano silica particles (NS) and multi-walled carbon nanotubes (MWCNT) on enhancing both the compressive and flexural strengths of the cement paste was investigated. Moreover, the morphology of the interface between cement paste and aggregates was studied by scanning electron microscopy (SEM). The mixtures were prepared using three different portions of MWCNT and NS. …

Go to article

Implications Of An Improved Water Equation Of State For Water-Rich Planets, Chenling Huang, David R. Rice, Zachary M. Grande, Dean Smith, John H. Boisvert, Oliver Tschauner, Ashkan Salamat, Jason Steffen Mar 2021

Implications Of An Improved Water Equation Of State For Water-Rich Planets, Chenling Huang, David R. Rice, Zachary M. Grande, Dean Smith, John H. Boisvert, Oliver Tschauner, Ashkan Salamat, Jason Steffen

Geoscience Faculty Publications

Water (H2O), in all forms, is an important constituent in planetary bodies, controlling habitability and influencing geological activity. Under conditions found in the interior of many planets, as the pressure increases, the H-bonds in water gradually weaken and are replaced by ionic bonds. Recent experimental measurements of the water equation of state (EOS) showed both a new phase of H-bonded water ice, ice-VIIt, and a relatively low transition pressure just above 30 GPa to ionic bonded ice-X, which has a bulk modulus 2.5 times larger. The higher bulk modulus of ice-X produces larger planets for a given mass, thereby either …

Go to article

Growing Biodiverse Urban Futures: Renaturalization And Rewilding As Strategies To Strengthen Urban Resilience, Steffen Lehmann Mar 2021

Growing Biodiverse Urban Futures: Renaturalization And Rewilding As Strategies To Strengthen Urban Resilience, Steffen Lehmann

Architecture Faculty Research

How are our cities using nature-based solutions to confront the challenges posed by a warming climate, the loss of biodiversity and major resource depletion? This article discusses the opportunities and benefits of applying the concepts of regreening and rewilding of cities. The article engages with key sources and summarizes the background and development of regreening and nature-based solutions and important policies, concerns and perspectives of international and national organizations. It introduces the integration of nature-based solutions (NBS) as a strategy in urban planning with the aim to strengthen urban resilience and to slow down the biodiversity decline. Rewilding areas in …

Go to article

Renewable Energy Generation And Ghg Emission Reduction Potential Of A Satellitewater Reuse Plant By Using Solar Photovoltaics And Anaerobic Digestion, Jonathan R. Bailey, Saria Bukhary, Jacimaria R. Batista, Sajjad Ahmad Feb 2021

Renewable Energy Generation And Ghg Emission Reduction Potential Of A Satellitewater Reuse Plant By Using Solar Photovoltaics And Anaerobic Digestion, Jonathan R. Bailey, Saria Bukhary, Jacimaria R. Batista, Sajjad Ahmad

Civil and Environmental Engineering and Construction Faculty Research

Wastewater treatment is a very energy-intensive process. The growing population, increased demands for energy and water, and rising pollution levels caused by fossil-fuel-based energy generation, warrants the transition from fossil fuels to renewable energy. This research explored the energy consumption offset of a satellite water reuse plant (WRP) by using solar photovoltaics (PVs) and anaerobic digestion. The analysis was performed for two types of WRPs: conventional (conventional activated sludge system (CAS) bioreactor with secondary clarifiers and dual media filtration) and advanced (bioreactor with membrane filtration (MBR)) treatment satellite WRPs. The associated greenhouse gas (GHG) emissions were also evaluated. For conventional …

Go to article

Machine Learning Approaches For The Prediction Of Bone Mineral Density By Using Genomic And Phenotypic Data Of 5130 Older Men, Qing Wu, Fatma Nasoz, Jongyun Jung, Bibek Bhattarai, Mira V. Han, Robert A. Greenes, Kenneth G. Saag Feb 2021

Machine Learning Approaches For The Prediction Of Bone Mineral Density By Using Genomic And Phenotypic Data Of 5130 Older Men, Qing Wu, Fatma Nasoz, Jongyun Jung, Bibek Bhattarai, Mira V. Han, Robert A. Greenes, Kenneth G. Saag

School of Medicine Faculty Publications

The study aimed to utilize machine learning (ML) approaches and genomic data to develop a prediction model for bone mineral density (BMD) and identify the best modeling approach for BMD prediction. The genomic and phenotypic data of Osteoporotic Fractures in Men Study (n = 5130) was analyzed. Genetic risk score (GRS) was calculated from 1103 associated SNPs for each participant after a comprehensive genotype imputation. Data were normalized and divided into a training set (80%) and a validation set (20%) for analysis. Random forest, gradient boosting, neural network, and linear regression were used to develop BMD prediction models separately. Ten-fold …

Go to article

Computation And Data Driven Discovery Of Topological Phononic Materials, Jiangxu Li, Jiaxi Liu, Stanley A. Baronett, Mingfeng Liu, Lei Wang, Ronghan Li, Yun Chen, Dianzhong Li, Qiang Zhu, Xing Qiu Chen Feb 2021

Computation And Data Driven Discovery Of Topological Phononic Materials, Jiangxu Li, Jiaxi Liu, Stanley A. Baronett, Mingfeng Liu, Lei Wang, Ronghan Li, Yun Chen, Dianzhong Li, Qiang Zhu, Xing Qiu Chen

Physics & Astronomy Faculty Research

© 2021, The Author(s). The discovery of topological quantum states marks a new chapter in both condensed matter physics and materials sciences. By analogy to spin electronic system, topological concepts have been extended into phonons, boosting the birth of topological phononics (TPs). Here, we present a high-throughput screening and data-driven approach to compute and evaluate TPs among over 10,000 real materials. We have discovered 5014 TP materials and grouped them into two main classes of Weyl and nodal-line (ring) TPs. We have clarified the physical mechanism for the occurrence of single Weyl, high degenerate Weyl, individual nodal-line (ring), nodal-link, nodal-chain, …

Go to article

The Pencil Code, A Modular Mpi Code For Partial Differential Equations And Particles: Multipurpose And Multiuser-Maintained, The Pencil Code Collaboration, Chao-Chin Yang Feb 2021

The Pencil Code, A Modular Mpi Code For Partial Differential Equations And Particles: Multipurpose And Multiuser-Maintained, The Pencil Code Collaboration, Chao-Chin Yang

Physics & Astronomy Faculty Research

The Pencil Code is a highly modular physics-oriented simulation code that can be adapted to a wide range of applications. It is primarily designed to solve partial differential equations (PDEs) of compressible hydrodynamics and has lots of add-ons ranging from astrophysical magnetohydrodynamics (MHD) (A. Brandenburg & Dobler, 2010) to meteorological cloud microphysics (Li et al., 2017) and engineering applications in combustion (Babkovskaia et al., 2011). Nevertheless, the framework is general and can also be applied to situations not related to hydrodynamics or even PDEs, for example when just the message passing interface or input/output strategies of the code are to …

Go to article

Constraining Protoplanetary Disc Accretion And Young Planets Using Alma Kinematic Observations, Ian Rabago, Zhaohuan Zhu Feb 2021

Constraining Protoplanetary Disc Accretion And Young Planets Using Alma Kinematic Observations, Ian Rabago, Zhaohuan Zhu

Physics & Astronomy Faculty Research

Recent ALMA molecular line observations have revealed 3D gas velocity structure in protoplanetary discs, shedding light on mechanisms of disc accretion and structure formation. (1) By carrying out viscous simulations, we confirm that the disc's velocity structure differs dramatically using vertical stress profiles from different accretion mechanisms. Thus, kinematic observations tracing flows at different disc heights can potentially distinguish different accretion mechanisms. On the other hand, the disc surface density evolution is mostly determined by the vertically integrated stress. The sharp disc outer edge constrained by recent kinematic observations can be caused by a radially varying alpha in the disc. …

Go to article

Piezomagnetic Switching And Complex Phase Equilibria In Uranium Dioxide, Daniel J. Antonio, Joel T. Weiss, Katherine S. Shanks, Jacob P.C. Ruff, Marcelo Jaime, Andres Saul, Thomas Swinburne, Myron Salamon, Keshav Shrestha, Barbara Lavina, Daniel Koury, Sol M. Gruner, David A. Andersson, Christopher R. Stanek, Tomasz Durakiewicz, James L. Smith, Zahirul Islam, Krzysztof Gofryk Feb 2021

Piezomagnetic Switching And Complex Phase Equilibria In Uranium Dioxide, Daniel J. Antonio, Joel T. Weiss, Katherine S. Shanks, Jacob P.C. Ruff, Marcelo Jaime, Andres Saul, Thomas Swinburne, Myron Salamon, Keshav Shrestha, Barbara Lavina, Daniel Koury, Sol M. Gruner, David A. Andersson, Christopher R. Stanek, Tomasz Durakiewicz, James L. Smith, Zahirul Islam, Krzysztof Gofryk

Physics & Astronomy Faculty Research

Actinide materials exhibit strong spin-lattice coupling and electronic correlations, and are predicted to host new emerging ground states. One example is piezomagnetism and magneto-elastic memory effect in the antiferromagnetic Mott-Hubbard insulator uranium dioxide, though its microscopic nature is under debate. Here, we report X-ray diffraction studies of oriented uranium dioxide crystals under strong pulsed magnetic fields. In the antiferromagnetic state a [888] Bragg diffraction peak follows the bulk magnetostriction that expands under magnetic fields. Upon reversal of the field the expansion turns to contraction, before the [888] peak follows the switching effect and piezomagnetic 'butterfly' behaviour, characteristic of two structures …

Go to article

Coexistence Of Metamagnetism And Slow Relaxation Of Magnetization In Ammonium Hexafluoridorhenate, James Louis-Jean, Samundeeswari M. Balasekaran, Keith V. Lawler, Adrián Sanchis-Perucho, José Martínez-Lillo, Dean Smith, Paul M. Forster, Ashkan Salamat, Frederic Poineau Feb 2021

Coexistence Of Metamagnetism And Slow Relaxation Of Magnetization In Ammonium Hexafluoridorhenate, James Louis-Jean, Samundeeswari M. Balasekaran, Keith V. Lawler, Adrián Sanchis-Perucho, José Martínez-Lillo, Dean Smith, Paul M. Forster, Ashkan Salamat, Frederic Poineau

Chemistry and Biochemistry Faculty Research

© The Royal Society of Chemistry 2021. The (NH4)2[ReF6] (1) salt was studied by X-ray diffraction, Raman spectroscopy, theoretical calculations, and magnetic measurements.1crystallizes in the trigonal space groupP3̄m1 (Re-F = 1.958(5) Å). In the Raman spectrum of1, splitting of the observed peaks was observed and correlated to the valence frequencies of vibration of the [ReF6]2−anion. The study of the magnetic properties of1, through DC and AC magnetic susceptibility measurements, reveals the coexistence of metamagnetism and slow relaxation of magnetization at low temperature, which is unusual in the molecular systems based on the paramagnetic 5d metal ions reported so far.

Go to article

Kozai–Lidov Oscillations Triggered By A Tilt Instability Of Detached Circumplanetary Discs, Rebecca G. Martin, Zhaohuan Zhu, Philip J. Armitage, Chao-Chin Yang, Hans Baehr Jan 2021

Kozai–Lidov Oscillations Triggered By A Tilt Instability Of Detached Circumplanetary Discs, Rebecca G. Martin, Zhaohuan Zhu, Philip J. Armitage, Chao-Chin Yang, Hans Baehr

Physics & Astronomy Faculty Research

Circumplanetary discs can be linearly unstable to the growth of disc tilt in the tidal potential of the star–planet system. We use 3D hydrodynamical simulations to characterize the disc conditions needed for instability, together with its long-term evolution. Tilt growth occurs for disc aspect ratios, evaluated near the disc outer edge, of H/r ≳ 0.05, with a weak dependence on viscosity in the wave-like regime of warp propagation. Lower mass giant planets are more likely to have circumplanetary discs that satisfy the conditions for instability. We show that the tilt instability can excite the inclination to above the threshold where …

Go to article

Nickel Isotopic Evidence For Late-Stage Accretion Of Mercury-Like Differentiated Planetary Embryos, Shui Jiong Wang, Wenzhong Wang, Jian Ming Zhu, Zhongqing Wu, Jingao Liu, Guilin Han, Fang Zhen Teng, Shichun Huang, Hongjie Wu, Yujian Wang, Guangliang Wu, Weihan Li Jan 2021

Nickel Isotopic Evidence For Late-Stage Accretion Of Mercury-Like Differentiated Planetary Embryos, Shui Jiong Wang, Wenzhong Wang, Jian Ming Zhu, Zhongqing Wu, Jingao Liu, Guilin Han, Fang Zhen Teng, Shichun Huang, Hongjie Wu, Yujian Wang, Guangliang Wu, Weihan Li

Geoscience Faculty Publications

© 2021, The Author(s). Earth’s habitability is closely tied to its late-stage accretion, during which impactors delivered the majority of life-essential volatiles. However, the nature of these final building blocks remains poorly constrained. Nickel (Ni) can be a useful tracer in characterizing this accretion as most Ni in the bulk silicate Earth (BSE) comes from the late-stage impactors. Here, we apply Ni stable isotope analysis to a large number of meteorites and terrestrial rocks, and find that the BSE has a lighter Ni isotopic composition compared to chondrites. Using first-principles calculations based on density functional theory, we show that core-mantle …

Go to article

First Prev Next Last