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Articles 2371 - 2400 of 7341

Full-Text Articles in Physical Sciences and Mathematics

13 Spherical Coordinates, Charles G. Torre Aug 2014

13 Spherical Coordinates, Charles G. Torre

Foundations of Wave Phenomena

The spherical coordinates of a point p can be obtained by the following geometric construction. The value of r represents the distance from the point p to the origin (which you can put wherever you like). The value of ✓ is the angle between the positive z-axis and a line l drawn from the origin to p. The value of " is the angle made with the x-axis by the projection of l into the x-y plane (z = 0). Note: for points in the x-y plane, r and " (not ✓) are polar coordinates. The coordinates (r, ✓, ") …

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09 The Wave Equation In 3 Dimensions, Charles G. Torre Aug 2014

09 The Wave Equation In 3 Dimensions, Charles G. Torre

Foundations of Wave Phenomena

We now turn to the 3-dimensional version of the wave equation, which can be used to describe a variety of wavelike phenomena, e.g., sound waves and electromagnetic waves. One could derive this version of the wave equation much as we did the one-dimensional version by generalizing our line of coupled oscillators to a 3-dimensional array of oscillators. For many purposes, e.g., modeling propagation of sound, this provides a useful discrete model of a three dimensional solid.

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Problem Set 4, Charles G. Torre Aug 2014

Problem Set 4, Charles G. Torre

Foundations of Wave Phenomena

Problem Set 4

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Visualizing And Forecasting Box-Office Revenues: A Case Study Of The James Bond Movie Series, Vahan Petrosyan Aug 2014

Visualizing And Forecasting Box-Office Revenues: A Case Study Of The James Bond Movie Series, Vahan Petrosyan

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

This Master's report deals with the visualization and forecasting of the box-office revenues and some related variables from the James Bond movie Series. Visualization techniques such as time series plots, scatterplot matrices, dotplots, boxplots, histograms, normal quantile plots, parallel coordinates plots, heatmaps, mosaic plots, association plots, and choropleth maps are used to provide some deeper insights into the given dataset. Additionally, the results from an article published in 1997 are reproduced and extended. This article modeled the box-office revenues of the James Bond movie series. Numerous statistical models were examined to obtain the models that are closest to the original …

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Weyl Gravity As General Relativity, James Thomas Wheeler Jul 2014

Weyl Gravity As General Relativity, James Thomas Wheeler

James Thomas Wheeler

When the full connection of Weyl conformal gravity is varied instead of just the metric, the resulting vacuum field equations reduce to the vacuum Einstein equation, up to the choice of local units, if and only if the torsion vanishes. This result differs strongly from the usual fourth-order formulation of Weyl gravity.

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Exploring The Possibilities Of A Cellular Automata In Minecraft, Stephen Saunders Jul 2014

Exploring The Possibilities Of A Cellular Automata In Minecraft, Stephen Saunders

Undergraduate Honors Capstone Projects

Complex systems are not always generated by complex individuals. Simple, cell-like individuals can produce sophisticated outcomes. Structures implementing this nature are called cellular automaton. In this paper, we discuss the difficulties associated with the creation of one such automaton in a pre-existing environment, in this case the game MineCraft. A subsequent study of the behavior of this automaton is presented, using an objective information measure called set complexity.

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The Life Cycle Of Instability Features Measured From The Andes Lidar Observatory Over Cerro Pachon On 24 March 2012, J. H. Hecht, K. Wan, L. J. Gelinas, David C. Fritts, R. L. Walterscheid, R. J. Rudy, A. Z. Liu, S. J. Franke, F. A. Vargas, Pierre-Dominique Pautet, Michael J. Taylor, G. R. Swenson Jun 2014

The Life Cycle Of Instability Features Measured From The Andes Lidar Observatory Over Cerro Pachon On 24 March 2012, J. H. Hecht, K. Wan, L. J. Gelinas, David C. Fritts, R. L. Walterscheid, R. J. Rudy, A. Z. Liu, S. J. Franke, F. A. Vargas, Pierre-Dominique Pautet, Michael J. Taylor, G. R. Swenson

Publications

The Aerospace Corporation's Nightglow Imager (ANI) observes nighttime OH emission (near 1.6 μm) every 2 s over an approximate 73° field of view. ANI had previously been used to study instability features seen over Maui. Here we describe observations of instabilities seen from 5 to 8 UT on 24 March 2012 over Cerro Pachon, Chile, and compare them with previous results from Maui, with theory, and with Direct Numerical Simulations (DNS). The atmosphere had reduced stability because of the large negative temperature gradients measured by a Na lidar. Thus, regions of dynamical and convective instabilities are expected to form, depending …

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Variations In Cathodoluminescent Intensity Of Spacecraft Materials Exposed To Energetic Electron Bombardment, Justin Dekany, Justin Christensen, Jr Dennison, Amberly Evans Jensen, Gregory Wilson, Todd Schneider, Charles W. Bowers, Robert Meloy Jun 2014

Variations In Cathodoluminescent Intensity Of Spacecraft Materials Exposed To Energetic Electron Bombardment, Justin Dekany, Justin Christensen, Jr Dennison, Amberly Evans Jensen, Gregory Wilson, Todd Schneider, Charles W. Bowers, Robert Meloy

Conference Proceedings

Many contemporary spacecraft materials exhibit cathodoluminescence when exposed to electron flux from the space plasma environment. A quantitative, physics-based model has been developed to predict the intensity of the glow as a function of incident electron current density and energy, temperature, and intrinsic material properties. We present a comparative study of the absolute spectral radiance for several types of dielectric and composite materials based on this model which spans three orders of magnitude. Variations in intensity are contrasted for different electron environments, different sizes of samples and sample sets, different testing and analysis methods, and data acquired at different test …

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Electrostatic Discharge And Endurance Time Measurements Of Spacecraft Materials: A Defect-Driven Dynamic Model, Allen Andersen, Jr Dennison, Alec M. Sim, Charles Sim Jun 2014

Electrostatic Discharge And Endurance Time Measurements Of Spacecraft Materials: A Defect-Driven Dynamic Model, Allen Andersen, Jr Dennison, Alec M. Sim, Charles Sim

Conference Proceedings

Electrostatic breakdown leads to the majority of anomalies and failures attributed to spacecraft interactions with the plasma space environment. It is therefore critical to understand how electrostatic field strength (FESD) of spacecraft materials varies due to environmental conditions such as duration of applied electric field, rate of field change, history of exposure to high fields, and temperature. We have developed a dual-defect, thermodynamic, mean-field trapping model in terms of recoverable and irrecoverable defect modes to predict probabilities of breakdown. Fits to a variety of measurements of the dependence of FESD of insulating polymers on endurance time, voltage ramp rate, and …

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The Dynamic Interplay Between Spacecraft Charging, Space Environment Interactions And Evolving Materials, Jr Dennison Jun 2014

The Dynamic Interplay Between Spacecraft Charging, Space Environment Interactions And Evolving Materials, Jr Dennison

Conference Proceedings

While the effects on spacecraft charging from varying environmental conditions and from the selection of different construction materials have been studied extensively, modification of materials properties by exposure to the space plasma environment can also have profound effects on spacecraft charging. Given the increasingly demanding nature of space missions, there is a clear need to extend our understanding of the dynamic nature of material properties that affect spacecraft charging and to expand our knowledge base of materials’ responses to specific environmental conditions so that we can more reliably predict the long term response of spacecraft to their environment. This paper …

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Defects Density Of States Model Of Cathodoluminescent Intensity And Spectra Of Disordered Sio2, Amberly Evans Jensen, Jr Dennison Jun 2014

Defects Density Of States Model Of Cathodoluminescent Intensity And Spectra Of Disordered Sio2, Amberly Evans Jensen, Jr Dennison

Conference Proceedings

Electron beam measurements have been made that show disordered SiO 2 exhibits luminescent behavior, and that it varies with incident beam energy and current density, sample temperature and wavelength. A simple model based on the electronic band structure and defect density of states—initially used to explain electron transport in highly disordered insulating materials—has been extended to predict the relative cathodoluminescent intensity and spectral radiance for disordered SiO 2 as a function of these variables. Insulating SiO 2 has a band gap of ~8.9 eV. Hence thermal excitation from the valence to conduction band is highly improbable; excitation is through collisions …

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Density Of State Models And Temperature Dependence Of Radiation Induced Conductivity, Jodie Corbridge Gillespie, Jr Dennison, Alec M. Sim Jun 2014

Density Of State Models And Temperature Dependence Of Radiation Induced Conductivity, Jodie Corbridge Gillespie, Jr Dennison, Alec M. Sim

Conference Proceedings

Expressions are developed for radiation induce conductivity (RIC) over an extended temperature range, based on density of states models for highly disordered insulating materials. A general discussion of the DOS of can be given using two simple types of DOS distributions of defect states within the bandgap for disordered materials are considered, one that monotonically decreases within the bandgap and one with a distribution peak within the band gap. Three monotonically decreasing models (exponential, power law, and linear), and two peaked models (Gaussian and delta function) are considered, plus limiting cases with a uniform DOS for each type. Variations using …

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Synergistic Models Of Electron Emission And Transport Measurements Of Disordered Sio2, Jr Dennison, Justin Dekany, Jodie C. Gillespie, Phil Lundgreen, Allen Andersen, Amberly Evans, Greg Wilson, Alec Sim, Ryan Carl Hoffmann Jun 2014

Synergistic Models Of Electron Emission And Transport Measurements Of Disordered Sio2, Jr Dennison, Justin Dekany, Jodie C. Gillespie, Phil Lundgreen, Allen Andersen, Amberly Evans, Greg Wilson, Alec Sim, Ryan Carl Hoffmann

Presentations

No abstract provided.

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Measurements Of Intrinsic Electron Emission Yields Of High Resistivity Ceramic Materials, Justin Dekany, Jr Dennison, Ryan Carl Hoffmann, Clint D. Thomson, Ender Savrun Jun 2014

Measurements Of Intrinsic Electron Emission Yields Of High Resistivity Ceramic Materials, Justin Dekany, Jr Dennison, Ryan Carl Hoffmann, Clint D. Thomson, Ender Savrun

Presentations

No abstract provided.

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Defects Density Of States Model Of Cathodoluminescent Intensity And Spectra Of Disordered Sio2,, Amberly Evans Jensen, Jr Dennison Jun 2014

Defects Density Of States Model Of Cathodoluminescent Intensity And Spectra Of Disordered Sio2,, Amberly Evans Jensen, Jr Dennison

Presentations

Electron beam measurements have shown that disordered SiO2 exhibits luminescent behavior, which varies with incident beam energy and current density, sample temperature (T), exposure time, and wavelength. A simple model based on the electronic band structure and defect density of states—used to explain electron transport in highly disordered insulating materials—has been extended to predict the relative cathodoluminescent intensity and spectral radiance for disordered SiO 2 as a function of these variables. Insulating SiO2 has a band gap of ~8.9 eV. Hence thermal excitation from the valence to conduction band is highly improbable; excitation is through collisions of the incident high …

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Defects Density Of States Model Of Cathodoluminescent Intensity And Spectra Of Disordered Sio2, Amberly Evans Jensen, Jr Dennison Jun 2014

Defects Density Of States Model Of Cathodoluminescent Intensity And Spectra Of Disordered Sio2, Amberly Evans Jensen, Jr Dennison

Presentations

No abstract provided.

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Density Of State Models And Temperature Dependence Of Radiation Induced Conductivity, Jodie Corbridge Gillespie, Jr Dennison, Alec M. Sim Jun 2014

Density Of State Models And Temperature Dependence Of Radiation Induced Conductivity, Jodie Corbridge Gillespie, Jr Dennison, Alec M. Sim

Presentations

Radiation induced conductivity (RIC) occurs when incident ionizing radiation deposits energy and excites electrons into the conduction band of insulators. The increased number of charge carriers, and hence the magnitude of the enhanced conductivity, is dependent on a number of factors including temperature and the spatial and energy dependence and occupation of the material’s distribution of localized trap states within the band gap—or density of states (DOS). Expressions for RIC in terms of the filling of the DOS up to an effective Fermi level were largely developed by Rose [RCA Review, 1951], and were extended by Fowler [ …

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Density Of State Models And Temperature Dependence Of Radiation Induced Conductivity, Jodie C. Gillespie, Jr Dennison, Alec Sim Jun 2014

Density Of State Models And Temperature Dependence Of Radiation Induced Conductivity, Jodie C. Gillespie, Jr Dennison, Alec Sim

Presentations

No abstract provided.

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Synergistic Models Of Electron Emission And Transport Measurements Of Disordered Sio2, Jr Dennison, Justin Dekany, Jodie Corbridge Gillespie, Phil Lundgreen, Allen Andersen, Amberly Evans Jensen, Gregory Wilson, Alec Sim, Ryan Hoffmann Jun 2014

Synergistic Models Of Electron Emission And Transport Measurements Of Disordered Sio2, Jr Dennison, Justin Dekany, Jodie Corbridge Gillespie, Phil Lundgreen, Allen Andersen, Amberly Evans Jensen, Gregory Wilson, Alec Sim, Ryan Hoffmann

Presentations

A critical component in the prediction and mitigation of spacecraft charging issues is an accurate model of the charging, transport and electron emission properties of a broad array of materials used in the construction of spacecraft. The increased sensitivity, longer-duration missions, and ventures into more demanding environments only serve to heighten this need. One important way for the spacecraft charging community to address this issue is to expand the role of more fundamental materials physics. This includes the development of unifying theoretical models of the charge transport equations based on the creation, distribution, and occupancy of defect densities of states. …

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Electrostatic Discharge And Endurance Time Measurements Of Spacecraft Materials: A Defect-Driven Dynamic Model, Allen Andersen, Jr Dennison, Alec Sim, Charles Sim Jun 2014

Electrostatic Discharge And Endurance Time Measurements Of Spacecraft Materials: A Defect-Driven Dynamic Model, Allen Andersen, Jr Dennison, Alec Sim, Charles Sim

Presentations

Electrostatic discharge (ESD) is the primary cause of space environment induced failures and malfunctions. As mission lifetimes and the sensitivity and complexity of instrumentation increase, so does the need for describing the influence of the electrical aging processes on ESD. This research studies the electrostatic field strength (FESD) of polymeric insulators as a function of applied field and the time-to-breakdown for F < FESD. A dynamic physics-based model for time-to-breakdown is much more valuable than an empirical static model, since it provides the ability to predict the statistical lifetime of dielectric materials subjected to prolonged stress from …

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Variations In Cathodoluminescent Intensity Of Spacecraft Materials Exposed To Energetic Electron Bombardment, Justin Dekany, Justin Christensen, Jr Dennison, Amberly Evans Jensen, Gregory Wilson, Todd Schneider, Charles W. Bowers, Robert Meloy Jun 2014

Variations In Cathodoluminescent Intensity Of Spacecraft Materials Exposed To Energetic Electron Bombardment, Justin Dekany, Justin Christensen, Jr Dennison, Amberly Evans Jensen, Gregory Wilson, Todd Schneider, Charles W. Bowers, Robert Meloy

Presentations

Various highly insulating materials used in spacecraft construction can exhibit glow (electron-induced luminescence or cathodoluminescence) when exposed to the space plasma environment. Measurements of the absolute and relative cathodoluminescent intensity per incident electron flux of spacecraft materials are essential to predict and mitigate consequences for optical detection and for stray light contamination in space-based observatories. They also provide important information about the defect structure and electron transport properties of these materials. Previous studies have focused on how the relative spectral radiance of cathodoluminescent materials varies with changes in environmental conditions, including electron energy, current density, absorbed power density, and temperature. …

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Small Satellite Space Environments Effects Test Facility, Jr Dennison, Kent Hartley, Lisa Montierth Phillipps, Robert Johnson, Justin Dekany, James Dyer Jun 2014

Small Satellite Space Environments Effects Test Facility, Jr Dennison, Kent Hartley, Lisa Montierth Phillipps, Robert Johnson, Justin Dekany, James Dyer

Presentations

A versatile space environments test facility has been designed and built to study the effects on small satellites and system components. Testing for potentially environmental-induced modifications of small satellites is critical to avoid possible deleterious or catastrophic effects over the duration of space missions. This is increasingly more important as small satellite programs have longer mission lifetimes, expand to more hash environments (such as polar or geosynchronous orbits), make more diverse and sensitive measurements, minimize shielding to reduce mass, and utilize more compact and sensitive electronics (often including untested off-the-shelf components). Our vacuum chamber is particularly well suited for cost-effective, …

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Electrostatic Discharge And Endurance Time Measurements Of Spacecraft Materials: A Defect-Driven Dynamic Model, Allen Andersen, Jr Dennison, Alec Sim, Charles Sim Jun 2014

Electrostatic Discharge And Endurance Time Measurements Of Spacecraft Materials: A Defect-Driven Dynamic Model, Allen Andersen, Jr Dennison, Alec Sim, Charles Sim

Presentations

No abstract provided.

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Variations In Cathodoluminescent Intensity Of Spacecraft Materials Exposed To Energetic Electron Bombardment, Justin Dekany, Justin Christensen, Jr Dennison, Amberly Evans, Greg Wilson, Todd Schneider, Charles W. Bowers, Robert H. Meloy Jun 2014

Variations In Cathodoluminescent Intensity Of Spacecraft Materials Exposed To Energetic Electron Bombardment, Justin Dekany, Justin Christensen, Jr Dennison, Amberly Evans, Greg Wilson, Todd Schneider, Charles W. Bowers, Robert H. Meloy

Presentations

No abstract provided.

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Midlatitude Mesospheric Temperature Anomalies During Major Ssw Events As Observed With Rayleigh-Scatter Lidar, Leda Sox, Vincent B. Wickwar, Chad Fish, Joshua P. Herron Jun 2014

Midlatitude Mesospheric Temperature Anomalies During Major Ssw Events As Observed With Rayleigh-Scatter Lidar, Leda Sox, Vincent B. Wickwar, Chad Fish, Joshua P. Herron

Graduate Student Posters

While the mesospheric temperature anomalies associated with Sudden Stratospheric Warmings (SSWs) have been observed extensively in the polar regions, observations of these anomalies at midlatitudes are sparse. The original Rayleigh-scatter lidar that operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) in the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU) collected a very dense set of temperature data for 11 years, from 1993 through 2004. The temperatures derived from these data extended over the mesosphere, from 45 to 90 km. This work focuses on the extensive Rayleigh lidar observations made during seven …

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Initial Measurements Of Mesospheric Gravity Waves Over Mcmurdo, Antarctica, Jonathan Pugmire, Michael J. Taylor, Yucheng Zhao, P.Dominique Pautet Jun 2014

Initial Measurements Of Mesospheric Gravity Waves Over Mcmurdo, Antarctica, Jonathan Pugmire, Michael J. Taylor, Yucheng Zhao, P.Dominique Pautet

Graduate Student Posters

The ANtarctic Gravity Wave Instrument Network (ANGWIN) is an NSF sponsored international program designed to develop and utilize a network of gravity wave observatories using existing and new instrumentation operated at several established research stations around the continent. The primary goal is to better understand and quantify large-scale gravity wave climatology and their effects on the upper atmosphere over Antarctica. ANGWIN currently comprises research measurements from five nations (U.S., U.K., Australia, Japan, and Brazil) at seven international stations. Utah State University’s Atmospheric Imaging Lab operates all-sky infrared and CCD imagers and an Advanced Mesospheric Temperature Mapper (AMTM) imager at several …

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Seasonal Variations Of Relative Neutral Densities Between 45 And 90 Km Determined From Usu Rayleigh Lidar Observations, David Barton, Vincent B. Wickwar, Leda Sox, Joshua P. Herron Jun 2014

Seasonal Variations Of Relative Neutral Densities Between 45 And 90 Km Determined From Usu Rayleigh Lidar Observations, David Barton, Vincent B. Wickwar, Leda Sox, Joshua P. Herron

Posters

A Rayleigh-scatter lidar operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W), part of Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU), collected extensive data between 1993 and 2004. From the Rayleigh lidar photon-count profiles, relative densities were determined throughout the mesosphere, from 45 to 90 km. Using these relative densities three climatologies were derived, each using a different density normalization at 45 km. The first normalized the relative densities to a constant; the second to the NRL-MSISe00 empirical model which has a strong annual component; and the third to the CPC analyses …

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Extremely Sensitive Rayleigh-Scatter Lidar At Usu, Vincent B. Wickwar, Leda Sox, David Barton, Matthew T. Emerick Jun 2014

Extremely Sensitive Rayleigh-Scatter Lidar At Usu, Vincent B. Wickwar, Leda Sox, David Barton, Matthew T. Emerick

Posters

Rayleigh lidar opened a portion of the atmosphere, from 30 to 90 km, to ground-based observations. Rayleigh-scatter observations were made at the Atmospheric Lidar Observatory (ALO) at Utah State University (USU) from 1993–2004 between 45 and 90 km, creating a very dense data set consisting of ~5000 hours of observations carried out over ~900 nights. The lidar had a mirror of area 0.15 m2 and a frequency-doubled Nd:YAG laser operating at 532 nm at 30 Hz at ~21 W, giving a power-aperture product (PAP) of ~3.1 Wm2.

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Interpretation (Or Is It Calibration?) Of Rayleigh-Scatter Lidar Signals, Vincent B. Wickwar, Leda Sox Jun 2014

Interpretation (Or Is It Calibration?) Of Rayleigh-Scatter Lidar Signals, Vincent B. Wickwar, Leda Sox

Presentations

No abstract provided.

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Bug/Problem Report Form, Ian M. Anderson Jun 2014

Bug/Problem Report Form, Ian M. Anderson

Downloads

No abstract provided.

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