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Full-Text Articles in Physical Sciences and Mathematics

Nifty Data Structures Projects, Ed Jorgensen, Laxmi Gewali Feb 2019

Nifty Data Structures Projects, Ed Jorgensen, Laxmi Gewali

UNLV Best Teaching Practices Expo

For computer science, and many technical fields, it is recognized that projects with real-world applicability play a significant roll in what students get out of the course. Creating applicable projects for upper division such as our data structures classes is very difficult and time consuming. We have utilized the Nifty assignments concept and applied it locally to an upper division data structures course. Our primary goal is to provide a forum for the sharing of data structure project ideas and materials (as applicable).


Joint Determination Of Residential Relocation And Commuting: A Forecasting Experiment For Sustainable Land Use And Transportation Planning, Jaewon Lim, Jae Hong Kim Jan 2019

Joint Determination Of Residential Relocation And Commuting: A Forecasting Experiment For Sustainable Land Use And Transportation Planning, Jaewon Lim, Jae Hong Kim

Public Policy and Leadership Faculty Publications

This article applies matrix forecasting methods to the investigation of residential relocation and commuting patterns that are highly interconnected, but often analyzed separately. More specifically, using recent inter-county migration and commuting pattern data for the three largest metropolitan areas in California, it examines how residential relocation and commuting are associated in the regions and whether a unified framework—in which household relocation and commuting flow matrices are jointly determined—can improve the forecasting performance. The relocation–commuting association is found to differ substantially by region, suggesting the importance of region-specific factors in shaping the interrelationship. Joint forecasting, however, can attain ...


First-Principles Investigation Of Sc-Iii/Iv Under High Pressure, Sheng-Cai Zhu, Xiao-Zhi Yan, Scott Fredericks, Yan-Ling Li, Qiang Zhu Dec 2018

First-Principles Investigation Of Sc-Iii/Iv Under High Pressure, Sheng-Cai Zhu, Xiao-Zhi Yan, Scott Fredericks, Yan-Ling Li, Qiang Zhu

Physics & Astronomy Faculty Publications

Using an ab initio evolutionary structure prediction method in conjunction with density functional theory, we performed a systematic investigation of the structural transition of elemental scandium under pressure up to 250 GPa. Our prediction successfully reproduced several allotropes which have been reported in the literature, including the Sc-I, Sc-II, and Sc-V. Moreover, we observed a series of energetically degenerate and geometrically similar structures at 110–195 GPa, which can partly explain the experimental observations regarding the unsolved phases III and IV reported by Y. Akahama et al. [Phys. Rev. Lett. 94, 195503 (2005)]. A detailed comparison of the powder x-ray ...


The Disk Substructures At High Angular Resolution Project (Dsharp). Vi. Dust Trapping In Thin-Ringed Protoplanetary Disks, Cornelis P. Dullemond, Tilman Birnstiel, Jane Huang, Nicolás T. Kurtovic, Sean M. Andrews, Viviana V. Guzmán, Laura M. Pérez, Andrea Isella, Zhaohuan Zhu, Myriam Benisty, David J. Wilner, Xue-Ning Bai, John M. Carpenter, Shangjia Zhang, Luca Ricci Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). Vi. Dust Trapping In Thin-Ringed Protoplanetary Disks, Cornelis P. Dullemond, Tilman Birnstiel, Jane Huang, Nicolás T. Kurtovic, Sean M. Andrews, Viviana V. Guzmán, Laura M. Pérez, Andrea Isella, Zhaohuan Zhu, Myriam Benisty, David J. Wilner, Xue-Ning Bai, John M. Carpenter, Shangjia Zhang, Luca Ricci

Physics & Astronomy Faculty Publications

A large fraction of the protoplanetary disks observed with ALMA display multiple well-defined and nearly perfectly circular rings in the continuum, in many cases with substantial peak-to-valley contrast. The DSHARP campaign shows that several of these rings are very narrow in radial extent. In this Letter we test the hypothesis that these dust rings are caused by dust trapping in radial pressure bumps, and if confirmed, put constraints on the physics of the dust trapping mechanism. We model this process analytically in 1D, assuming axisymmetry. By comparing this model to the data, we find that all rings are consistent with ...


The Disk Substructures At High Angular Resolution Program (Dsharp). Viii. The Rich Ringed Substructures In The As 209 Disk, Viviana V. Guzmán, Jane Huang, Sean M. Andrews, Andrea Isella, Laura M. Pérez, John M. Carpenter, Cornelis P. Dullemond, Luca Ricci, Tilman Birnstiel, Shangjia Zhang, Zhaohuan Zhu, Xue-Ning Bai, Myriam Benisty, Karin I. Öberg, David J. Wilner Dec 2018

The Disk Substructures At High Angular Resolution Program (Dsharp). Viii. The Rich Ringed Substructures In The As 209 Disk, Viviana V. Guzmán, Jane Huang, Sean M. Andrews, Andrea Isella, Laura M. Pérez, John M. Carpenter, Cornelis P. Dullemond, Luca Ricci, Tilman Birnstiel, Shangjia Zhang, Zhaohuan Zhu, Xue-Ning Bai, Myriam Benisty, Karin I. Öberg, David J. Wilner

Physics & Astronomy Faculty Publications

The Disk Substructures at High Angular Resolution Program (DSHARP). VIII. The Rich Ringed Substructures in the AS 209 Disk


The Disk Substructures At High Angular Resolution Project (Dsharp). Iv. Characterizing Substructures And Interactions In Disks Around Multiple Star Systems, Nicolás T. Kurtovic, Laura M. Pérez, Myriam Benisty, Zhaohuan Zhu, Shangjia Zhang, Jane Huang, Sean M. Andrews, Cornelis P. Dullemond, Andrea Isella, Xue-Ning Bai, John M. Carpenter, Viviana V. Guzmán, Luca Ricci, David J. Wilner Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). Iv. Characterizing Substructures And Interactions In Disks Around Multiple Star Systems, Nicolás T. Kurtovic, Laura M. Pérez, Myriam Benisty, Zhaohuan Zhu, Shangjia Zhang, Jane Huang, Sean M. Andrews, Cornelis P. Dullemond, Andrea Isella, Xue-Ning Bai, John M. Carpenter, Viviana V. Guzmán, Luca Ricci, David J. Wilner

Physics & Astronomy Faculty Publications

To characterize the substructures induced in protoplanetary disks by the interaction between stars in multiple systems, we study the 1.25 mm continuum and the 12CO(J = 2–1) spectral line emission of the triple systems HT Lup and AS 205, at scales of ≈5 au, as part of the "Disk Substructures at High Angular Resolution Project" (DSHARP). In the continuum emission, we find two symmetric spiral arms in the disk around AS 205 N, with a pitch angle of 14°, while the southern component AS 205 S, itself a spectroscopic binary, is surrounded by a compact inner disk and ...


The Disk Substructures At High Angular Resolution Project (Dsharp). Ix. A High-Definition Study Of The Hd 163296 Planet-Forming Disk, Andrea Isella, Jane Huang, Sean M. Andrews, Cornelis P. Dellemond, Tilman Birnstiel, Shangjia Zhang, Zhaohuan Zhu, Viviana V. Guzmán, Laura M. Pérez, Xue-Ning Bai, Myriam Benisty, John M. Carpenter, Luca Ricci, David J. Wilner Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). Ix. A High-Definition Study Of The Hd 163296 Planet-Forming Disk, Andrea Isella, Jane Huang, Sean M. Andrews, Cornelis P. Dellemond, Tilman Birnstiel, Shangjia Zhang, Zhaohuan Zhu, Viviana V. Guzmán, Laura M. Pérez, Xue-Ning Bai, Myriam Benisty, John M. Carpenter, Luca Ricci, David J. Wilner

Physics & Astronomy Faculty Publications

The Atacama Large Millimeter/submillimeter Array observations of protoplanetary disks acquired by the Disk Substructure at High Angular Resolution Project resolve the dust and gas emission on angular scales as small as 3 astronomical units, offering an unprecedented detailed view of the environment where planets form. In this Letter, we present and discuss observations of the HD 163296 protoplanetary disk that imaged the 1.25 mm dust continuum and 12CO J = 2–1 rotational line emission at a spatial resolution of 4 and 10 au, respectively. The continuum observations resolve and allow us to characterize the previously discovered dust rings ...


The Disk Substructures At High Angular Resolution Project (Dsharp). I. Motivation, Sample, Calibration, And Overview, Sean M. Andrews, Jane Huang, Laura M. Pérez, Andrea Isella, Cornelis P. Dullemond, Nicolás T. Kurtovic, Viviana V. Guzmán, John M. Carpenter, David J. Wilner, Shangjia Zhang, Zhaohuan Zhu, Tilman Birstiel, Xue-Ning Bai, Myriam Benisty, A. Meredith Hughes, Karin I. Öberg, Luca Ricci Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). I. Motivation, Sample, Calibration, And Overview, Sean M. Andrews, Jane Huang, Laura M. Pérez, Andrea Isella, Cornelis P. Dullemond, Nicolás T. Kurtovic, Viviana V. Guzmán, John M. Carpenter, David J. Wilner, Shangjia Zhang, Zhaohuan Zhu, Tilman Birstiel, Xue-Ning Bai, Myriam Benisty, A. Meredith Hughes, Karin I. Öberg, Luca Ricci

Physics & Astronomy Faculty Publications

We introduce the Disk Substructures at High Angular Resolution Project (DSHARP), one of the initial Large Programs conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The primary goal of DSHARP is to find and characterize substructures in the spatial distributions of solid particles for a sample of 20 nearby protoplanetary disks, using very high resolution (~0 035, or 5 au, FWHM) observations of their 240 GHz (1.25 mm) continuum emission. These data provide a first homogeneous look at the small-scale features in disks that are directly relevant to the planet formation process, quantifying their prevalence, morphologies, spatial scales ...


The Disk Substructures At High Angular Resolution Project (Dsharp). Iii. Spiral Structures In The Millimeter Continuum Of The Elias 27, Im Lup, And Waoph 6 Disks, Jane Huang, Sean M. Andrews, Laura M. Pérez, Zhaohuan Zhu, Cornelis P. Dullemond, Andrea Isella, Myriam Benisty, Xue-Ning Bai, Tilman Birnstiel, John M. Carpenter, Viviana V. Guzmán, A. Meredith Hughes, Karin I. Öberg, Luca Ricci, David J. Wilner, Shangjia Zhang Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). Iii. Spiral Structures In The Millimeter Continuum Of The Elias 27, Im Lup, And Waoph 6 Disks, Jane Huang, Sean M. Andrews, Laura M. Pérez, Zhaohuan Zhu, Cornelis P. Dullemond, Andrea Isella, Myriam Benisty, Xue-Ning Bai, Tilman Birnstiel, John M. Carpenter, Viviana V. Guzmán, A. Meredith Hughes, Karin I. Öberg, Luca Ricci, David J. Wilner, Shangjia Zhang

Physics & Astronomy Faculty Publications

We present an analysis of Atacama Large Millimeter/submillimeter Array 1.25 mm continuum observations of spiral structures in three protoplanetary disks from the Disk Substructures at High Angular Resolution Project. See full text for full abstract.


The Disk Substructures At High Angular Resolution Project (Dsharp). Ii. Characteristics Of Annular Substructures, Jane Huang, Sean M. Andrews, Cornelis P. Dellemond, Andrea Isella, Laura M. Pérez, Viviana V. Guzmán, Karin I. Öberg, Zhaohuan Zhu, Shangjia Zhang, Xue-Ning Bai, Myriam Benisty, Tilman Birstiel, John M. Carpenter, A. Meredith Hughes, Luca Ricci, Erik Weaver, David J. Wilner Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). Ii. Characteristics Of Annular Substructures, Jane Huang, Sean M. Andrews, Cornelis P. Dellemond, Andrea Isella, Laura M. Pérez, Viviana V. Guzmán, Karin I. Öberg, Zhaohuan Zhu, Shangjia Zhang, Xue-Ning Bai, Myriam Benisty, Tilman Birstiel, John M. Carpenter, A. Meredith Hughes, Luca Ricci, Erik Weaver, David J. Wilner

Physics & Astronomy Faculty Publications

The Disk Substructures at High Angular Resolution Project (DSHARP) used ALMA to map the 1.25 mm continuum of protoplanetary disks at a spatial resolution of ~5 au. We present a systematic analysis of annular substructures in the 18 single-disk systems targeted in this survey. No dominant architecture emerges from this sample; instead, remarkably diverse morphologies are observed. Annular substructures can occur at virtually any radius where millimeter continuum emission is detected and range in widths from a few astronomical units to tens of astronomical units. Intensity ratios between gaps and adjacent rings range from near-unity to just a few ...


The Disk Substructures At High Angular Resolution Project (Dsharp). Vii. The Planet–Disk Interactions Interpretation, Shangjia Zhang, Zhaohuan Zhu, Jane Huang, Viviana V. Guzmán, Sean M. Andrews, Tilman Birnstiel, Cornelis P. Dullemond, John M. Carpenter, Andrea Isella, Laura M. Pérez, Myriam Benisty, David J. Wilner, Clément Baruteau, Xue-Ning Bai, Luca Ricci Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). Vii. The Planet–Disk Interactions Interpretation, Shangjia Zhang, Zhaohuan Zhu, Jane Huang, Viviana V. Guzmán, Sean M. Andrews, Tilman Birnstiel, Cornelis P. Dullemond, John M. Carpenter, Andrea Isella, Laura M. Pérez, Myriam Benisty, David J. Wilner, Clément Baruteau, Xue-Ning Bai, Luca Ricci

Physics & Astronomy Faculty Publications

The Disk Substructures at High Angular Resolution Project (DSHARP) provides a large sample of protoplanetary disks with substructures that could be induced by young forming planets. To explore the properties of planets that may be responsible for these substructures, we systematically carry out a grid of 2D hydrodynamical simulations, including both gas and dust components. We present the resulting gas structures, including the relationship between the planet mass, as well as (1) the gaseous gap depth/width and (2) the sub/super-Keplerian motion across the gap. We then compute dust continuum intensity maps at the frequency of the DSHARP observations ...


The Disk Substructures At High Angular Resolution Project (Dsharp). X. Multiple Rings, A Misaligned Inner Disk, And A Bright Arc In The Disk Around The T Tauri Star Hd 143006, Laura M. Pérez, Myriam Benisty, Sean M. Andrews, Andrea Isella, Cornelis P. Dellemond, Jane Huang, Nicolás T. Kurtovic, Viviana V. Guzmán, Zhaohuan Zhu, Tilman Birnstiel, Shangjia Zhang, John M. Carpenter, David J. Wilner, Luca Ricci, Xue-Ning Bai, Erik Weaver, Karin I. Öberg Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). X. Multiple Rings, A Misaligned Inner Disk, And A Bright Arc In The Disk Around The T Tauri Star Hd 143006, Laura M. Pérez, Myriam Benisty, Sean M. Andrews, Andrea Isella, Cornelis P. Dellemond, Jane Huang, Nicolás T. Kurtovic, Viviana V. Guzmán, Zhaohuan Zhu, Tilman Birnstiel, Shangjia Zhang, John M. Carpenter, David J. Wilner, Luca Ricci, Xue-Ning Bai, Erik Weaver, Karin I. Öberg

Physics & Astronomy Faculty Publications

We present a detailed analysis of new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the disk around the T-Tauri star HD 143006, which at 46 mas (7.6 au) resolution reveals new substructures in the 1.25 mm continuum emission. The disk resolves into a series of concentric rings and gaps, together with a bright arc exterior to the rings that resembles hydrodynamical simulations of a vortex and a bridge-like feature connecting the two innermost rings. Although our 12CO observations at similar spatial resolution do not show obvious substructure, they reveal an inner disk depleted of CO emission. From ...


The Disk Substructures At High Angular Resolution Project (Dsharp). V. Interpreting Alma Maps Of Protoplanetary Disks In Terms Of A Dust Model, Tilman Birnstiel, Cornelis P. Dullemond, Zhaohuan Zhu, Sean M. Andrews, Xue-Ning Bai, David J. Wilner, John M. Carpenter, Jane Huang, Andrea Isella, Myriam Benisty, Laura M. Pérez, Shangjia Zhang Dec 2018

The Disk Substructures At High Angular Resolution Project (Dsharp). V. Interpreting Alma Maps Of Protoplanetary Disks In Terms Of A Dust Model, Tilman Birnstiel, Cornelis P. Dullemond, Zhaohuan Zhu, Sean M. Andrews, Xue-Ning Bai, David J. Wilner, John M. Carpenter, Jane Huang, Andrea Isella, Myriam Benisty, Laura M. Pérez, Shangjia Zhang

Physics & Astronomy Faculty Publications

The Disk Substructures at High Angular Resolution Project (DSHARP) is the largest homogeneous high-resolution (~0 035, or ~5 au) disk continuum imaging survey with the Atacama Large Millimeter/submillimeter Array (ALMA) so far. In the coming years, many more disks will be mapped with ALMA at similar resolution. Interpreting the results in terms of the properties and quantities of the emitting dusty material is, however, a very non-trivial task. This is in part due to the uncertainty in the dust opacities, an uncertainty that is not likely to be resolved any time soon. It is also partly due to the ...


Toward An Understanding Of Grb Prompt Emission Mechanism. Ii. Patterns Of Peak Energy Evolution And Their Connection To Spectral Lags, Z. Lucas Uhm, Bing Zhang, Judith Racusin Dec 2018

Toward An Understanding Of Grb Prompt Emission Mechanism. Ii. Patterns Of Peak Energy Evolution And Their Connection To Spectral Lags, Z. Lucas Uhm, Bing Zhang, Judith Racusin

Physics & Astronomy Faculty Publications

The prompt emission phase of gamma-ray bursts (GRBs) exhibits two distinct patterns of the peak energy (E p ) evolution, i.e., time-resolved spectral analyses of νF ν spectra of broad pulses reveal (1) "hard-to-soft" and (2) "flux-tracking" patterns of E p evolution in time, the physical origin of which still remains not well understood. We show here that these two patterns can be successfully reproduced within a simple physical model invoking synchrotron radiation in a bulk-accelerating emission region. We show further that the evolution patterns of the peak energy have, in fact, direct connections to the existence of two different ...


First Observation Of P-Odd Gamma Asymmetry In Polarized Neutron Capture On Hydrogen, D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, Alex Barzilov, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, C. B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer, G. L. Greene, J. Hall, J. Hamblen, C. Hayes, E. B. Iverson, M. L. Kabir Dec 2018

First Observation Of P-Odd Gamma Asymmetry In Polarized Neutron Capture On Hydrogen, D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, Alex Barzilov, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, C. B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer, G. L. Greene, J. Hall, J. Hamblen, C. Hayes, E. B. Iverson, M. L. Kabir

Mechanical Engineering Faculty Publications

We report the first observation of the parity-violating gamma-ray asymmetry A(gamma)(np) in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A(gamma)(np) isolates the Delta I = 1, S-3(1)-> P-3(1) component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory… See full text for full abstract.


Rare Helium-Bearing Compound Feo2he Stabilized At Deep-Earth Conditions, Jurong Zhang, Jian Lv, Hefei Li, Xiaolei Feng, Cheng Lu, Simon A. T. Redferm, Hanyu Liu, Changfeng Chen, Yanming Ma Dec 2018

Rare Helium-Bearing Compound Feo2he Stabilized At Deep-Earth Conditions, Jurong Zhang, Jian Lv, Hefei Li, Xiaolei Feng, Cheng Lu, Simon A. T. Redferm, Hanyu Liu, Changfeng Chen, Yanming Ma

Physics & Astronomy Faculty Publications

There is compelling geochemical evidence for primordial helium trapped in Earth’s lower mantle, but the origin and nature of the helium source remain elusive due to scarce knowledge on viable helium-bearing compounds that are extremely rare. Here we explore materials physics underlying this prominent challenge. Our structure searches in conjunction with first-principles energetic and thermodynamic calculations uncover a remarkable helium-bearing compound FeO2He at high pressure-temperature conditions relevant to the core-mantle boundary. Calculated sound velocities consistent with seismic data validate FeO2He as a feasible constituent in ultralow velocity zones at the lowermost mantle. These mutually corroborating findings establish the first ...


Review Of: The World Of Scary Video Games: A Study In Videoludic Horror, Approaches To Digital Game Studies, Matthew Murray Dec 2018

Review Of: The World Of Scary Video Games: A Study In Videoludic Horror, Approaches To Digital Game Studies, Matthew Murray

Library Faculty Publications

No abstract provided.


Probabilistic Interpretation Of Solutions Of Linear Ultraparabolic Equations, Michael D. Marcozzi Nov 2018

Probabilistic Interpretation Of Solutions Of Linear Ultraparabolic Equations, Michael D. Marcozzi

Math Faculty Publications

We demonstrate the existence, uniqueness and Galerkin approximatation of linear ultraparabolic terminal value/infinite-horizon problems on unbounded spatial domains. Furthermore, we provide a probabilistic interpretation of the solution in terms of the expectation of an associated ultradiffusion process.


Photospheric Radius Evolution Of Homologous Explosions, Liang-Duan Liu, Bing Zhang, Ling-Jun Wang, Zi-Gao Dai Nov 2018

Photospheric Radius Evolution Of Homologous Explosions, Liang-Duan Liu, Bing Zhang, Ling-Jun Wang, Zi-Gao Dai

Physics & Astronomy Faculty Publications

Recent wide-field surveys discovered new types of peculiar optical transients that showed diverse behaviors of the evolution of photospheric properties. We develop a general theory of homologous explosions with constant opacity, paying special attention to the evolution of the photospheric radius R ph. We find that regardless of the density distribution profile, R ph always increases early on and decreases at late times. This result does not depend on the radiation and cooling processes inside the ejecta. The general rising/falling behavior of R ph can be used to quickly diagnose whether the source originates from a supernova-like explosion. The ...


Boron Oxides Under Pressure: Prediction Of The Hardest Oxides, Huafeng Dong, Artem R. Oganov, Vadim V. Brazhkin, Qinggao Wang, Jin Zhang, M. Mahdi Davari Esfahani, Xiang-Feng Zhou, Fugen Wu, Qiang Zhu Nov 2018

Boron Oxides Under Pressure: Prediction Of The Hardest Oxides, Huafeng Dong, Artem R. Oganov, Vadim V. Brazhkin, Qinggao Wang, Jin Zhang, M. Mahdi Davari Esfahani, Xiang-Feng Zhou, Fugen Wu, Qiang Zhu

Physics & Astronomy Faculty Publications

We search for stable compounds of boron and oxygen at pressures from 0 to 500 GPa using the ab initio evolutionary algorithm uspex. Only two stable stoichiometries of boron oxides, namely, B6O and B2O3, are found to be stable, in good agreement with experiment. A hitherto unknown phase of B6O at ambient pressure, Cmcm−B6O, has recently been predicted by us and observed experimentally. For B2O3, we predict three previously unknown stable high-pressure phases—two of these (Cmc21 and P212121) are dynamically and mechanically stable at ambient pressure, and should be quenchable to ambient conditions. Their predicted hardnesses, reaching 33 ...


First-Principles Structural, Mechanical, And Thermodynamic Calculations Of The Negative Thermal Expansion Compound Zr2(Wo4)(Po4)2, Philippe F. Weck, Eunja Kim, Margaret E. Gordon, Jeffrey A. Greathouse, Remi Dingreville, Charles R. Bryan Nov 2018

First-Principles Structural, Mechanical, And Thermodynamic Calculations Of The Negative Thermal Expansion Compound Zr2(Wo4)(Po4)2, Philippe F. Weck, Eunja Kim, Margaret E. Gordon, Jeffrey A. Greathouse, Remi Dingreville, Charles R. Bryan

Physics & Astronomy Faculty Publications

The negative thermal expansion (NTE) material Zr2(WO4)(PO4)2 has been investigated for the first time within the framework of the density functional perturbation theory (DFPT). The structural, mechanical, and thermodynamic properties of this material have been predicted using the Perdew, Burke and Ernzerhof for solid (PBEsol) exchange–correlation functional, which showed superior accuracy over standard functionals in previous computational studies of the NTE material α-ZrW2O8. The bulk modulus calculated for Zr2(WO4)(PO4)2 using the Vinet equation of state at room temperature is K0 = 63.6 GPa, which is in close agreement with the experimental estimate of ...


Diffusion And Concentration Of Solids In The Dead Zone Of A Protoplanetary Disk, Chao-Chin Yang, Mordecai-Mark Mac Low, Anders Johansen Nov 2018

Diffusion And Concentration Of Solids In The Dead Zone Of A Protoplanetary Disk, Chao-Chin Yang, Mordecai-Mark Mac Low, Anders Johansen

Physics & Astronomy Faculty Publications

The streaming instability is a promising mechanism to drive the formation of planetesimals in protoplanetary disks. To trigger this process, it has been argued that sedimentation of solids onto the mid-plane needs to be efficient, and therefore that a quiescent gaseous environment is required. It is often suggested that dead-zone or disk-wind structure created by non-ideal magnetohydrodynamical (MHD) effects meets this requirement. However, simulations have shown that the mid-plane of a dead zone is not completely quiescent. In order to examine the concentration of solids in such an environment, we use the local-shearing-box approximation to simulate a particlegas system with ...


Bunching Coherent Curvature Radiation In Three-Dimensional Magnetic Field Geometry: Application To Pulsars And Fast Radio Bursts, Yuan-Pei Yang, Bing Zhang Nov 2018

Bunching Coherent Curvature Radiation In Three-Dimensional Magnetic Field Geometry: Application To Pulsars And Fast Radio Bursts, Yuan-Pei Yang, Bing Zhang

Physics & Astronomy Faculty Publications

The extremely high brightness temperatures of pulsars and fast radio bursts (FRBs) require their radiation mechanisms to be coherent. Coherent curvature radiation from bunches has been long discussed as the mechanism for radio pulsars and recently for FRBs. Assuming that bunches are already generated in pulsar magnetospheres, we calculate the spectrum of coherent curvature radiation under a three-dimensional magnetic field geometry. Different from previous works assuming parallel trajectories and a monoenergetic energy distribution of electrons, we consider a bunch characterized by its length, curvature radius of the trajectory family, bunch opening angle, and electron energy distribution. We find that the ...


Elevation And Azimuth-Aided Channel Estimation Scheme For Airborne Hyperspectral Data Transmission, Vahid Vahidi, Ebrahim Saberinia Nov 2018

Elevation And Azimuth-Aided Channel Estimation Scheme For Airborne Hyperspectral Data Transmission, Vahid Vahidi, Ebrahim Saberinia

Electrical and Computer Engineering Faculty Publications

A channel-estimation (CE) scheme is proposed to estimate the complex amplitude, Doppler shift, angle-of-departure, and angle-of-arrival of the channel taps for sparse and doubly selective channels for hyperspectral image transmission from unmanned aircraft vehicles (UAVs) to ground stations. The proposed method is dubbed as compressed-sensing joint parameter estimation (CS-JPE) and finds the channel parameters matrix by employing a compressed-sensing (CS)-based method. Afterward, a modified version of the joint parameter estimation (JPE) is proposed as CS-JPE and is dubbed as M-CS-JPE, which employs the elevation-azimuth angles of the line-of-sight channel tap to estimate the channel parameters with higher accuracy and ...


Fast Radio Burst Energetics And Detectability From High Redshifts, Bing Zhang Nov 2018

Fast Radio Burst Energetics And Detectability From High Redshifts, Bing Zhang

Physics & Astronomy Faculty Publications

We estimate the upper limit redshifts of known fast radio bursts (FRBs) using the dispersion measure (DM)-redshift (z) relation and derive the upper limit peak luminosity L p and energy E of FRBs within the observational band. The average z upper limits range from 0.17 to 3.10, the average L p upper limits range from 1.24 × 1042 erg s−1 to 7.80 × 1044 erg s−1, and the average E upper limits range from 6.91 × 1039 erg to 1.94 × 1042 erg. FRB 160102 with DM = 2596.1 ± 0.3 pc cm−3 likely ...


Linking Gait Dynamics To Mechanical Cost Of Legged Locomotion, David V. Lee, Sarah L. Harris Oct 2018

Linking Gait Dynamics To Mechanical Cost Of Legged Locomotion, David V. Lee, Sarah L. Harris

Life Sciences Faculty Publications

For millenia, legged locomotion has been of central importance to humans for hunting, agriculture, transportation, sport, and warfare. Today, the same principal considerations of locomotor performance and economy apply to legged systems designed to serve, assist, or be worn by humans in urban and natural environments. Energy comes at a premium not only for animals, wherein suitably fast and economical gaits are selected through organic evolution, but also for legged robots that must carry sufficient energy in their batteries. Although a robot's energy is spent at many levels, from control systems to actuators, we suggest that the mechanical cost ...


A Bayesian Framework For Exoplanet Direct Detection And Non-Detection, Jean-Baptiste Ruffio, Dimitri Mawet, Ian Czekala, Bruce Macintosh, Robert J. De Rosa, Garreth Ruane, Michael Bottom, Laurent Pueyo, Jason J. Wang, Lea Hirsch, Zhaohuan Zhu, Eric L. Nielsen Oct 2018

A Bayesian Framework For Exoplanet Direct Detection And Non-Detection, Jean-Baptiste Ruffio, Dimitri Mawet, Ian Czekala, Bruce Macintosh, Robert J. De Rosa, Garreth Ruane, Michael Bottom, Laurent Pueyo, Jason J. Wang, Lea Hirsch, Zhaohuan Zhu, Eric L. Nielsen

Physics & Astronomy Faculty Publications

Rigorously quantifying the information in high-contrast imaging data is important for informing follow-up strategies to confirm the substellar nature of a point source, constraining theoretical models of planet–disk interactions, and deriving planet occurrence rates. However, within the exoplanet direct imaging community, non-detections have almost exclusively been defined using a frequentist detection threshold (i.e., contrast curve) and associated completeness. This can lead to conceptual inconsistencies when included in a Bayesian framework. A Bayesian upper limit is such that the true value of a parameter lies below this limit with a certain probability. The associated probability is the integral of ...


Streaming Instability Of Multiple Particle Species In Protoplanetary Disks, Noemi Schaffer, Chao-Chin Yang, Anders Johansen Oct 2018

Streaming Instability Of Multiple Particle Species In Protoplanetary Disks, Noemi Schaffer, Chao-Chin Yang, Anders Johansen

Physics & Astronomy Faculty Publications

The radial drift and diffusion of dust particles in protoplanetary disks affect both the opacity and temperature of such disks, as well as the location and timing of planetesimal formation. In this paper, we present results of numerical simulations of particle-gas dynamics in protoplanetary disks that include dust grains with various size distributions. We have considered three scenarios in terms of particle size ranges, one where the Stokes number τs = 10−1−100, one where τs = 10−4−10−1, and finally one where τs= 10−3−100. Moreover, we considered both discrete and continuous distributions in particle size. In ...


Reaction Optimization Of Pyrazinoquinoxaline Based Organic Semiconductor With Cruciform Shape, Marco Valverde Paredes, Dong-Chan Lee Oct 2018

Reaction Optimization Of Pyrazinoquinoxaline Based Organic Semiconductor With Cruciform Shape, Marco Valverde Paredes, Dong-Chan Lee

LSAMP Poster Presentations

In this work, an optimum reaction condition was established to synthesize a pyrazinoquinoxaline based organic semiconductor with cruciform shape.


Multicolor Blackbody Emission In Grb 081221, Shu-Jin Hou, Bin-Bin Zhang, Yan-Zhi Meng, Xue-Feng Wu, En-Wei Liang, Hou-Jun Lü, Tong Liu, Yun-Feng Liang, Lin Lin, Rui-Jing Lu, Jin-Shu Huang, Bing Zhang Oct 2018

Multicolor Blackbody Emission In Grb 081221, Shu-Jin Hou, Bin-Bin Zhang, Yan-Zhi Meng, Xue-Feng Wu, En-Wei Liang, Hou-Jun Lü, Tong Liu, Yun-Feng Liang, Lin Lin, Rui-Jing Lu, Jin-Shu Huang, Bing Zhang

Physics & Astronomy Faculty Publications

The radiation mechanism of the prompt emission of gamma-ray bursts (GRBs) remains an open question. Although their spectra are usually well fitted with the empirical Band function, which is widely believed to be fully nonthermal and interpreted as an optically thin synchrotron emission, accumulating evidence shows that a thermal component actually exists. In this paper, a multicolor blackbody (mBB) model is proposed for the time-integrated spectrum of GRB 081221 by assuming a power-law distribution of the thermal luminosities with temperature, which manifests photospheric emissions from a different radius and/or angle. The effects of the minimum temperature kT min, the ...