Browsing by Subject "space"

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Capillary pressure in a porous medium with distinct pore surface and pore volume fractal dimensions
(2008-02) Deinert, M. R.; Dathe, A.; Parlange, J. Y.; Cady, K. B.; Deinert, M. R.; Deinert, M. R.
The relationship between capillary pressure and saturation in a porous medium often exhibits a power-law dependence. The physical basis for this relation has been substantiated by assuming that capillary pressure is directly related to the pore radius. When the pore space of a medium exhibits fractal structure this approach results in a power-law relation with an exponent of 3-D-v, where D-v is the pore volume fractal dimension. However, larger values of the exponent than are realistically allowed by this result have long been known to occur. Using a thermodynamic formulation for equilibrium capillary pressure we show that the standard result is a special case of the more general exponent (3-D-v)/(3-D-s) where D-s is the surface fractal dimension of the pores. The analysis reduces to the standard result when D-s=2, indicating a Euclidean relationship between a pore's surface area and the volume it encloses, and allows for a larger value for the exponent than the standard result when D-s>2.
Electromagnetic Earth-to Space Launch
(IEEE, 1989-01) Fair, H. D.; Coose, P.; Meinel, C. P.; Tidman, D. A.
The authors review several of the previous electromagnetic and electrothermal launch concepts and discuss the critical related technologies which are essential for the development of practical Earth-to-space launch systems. Selected missions and their requirements are discussed. Launcher concepts are briefly examined, and specific examples are given to demonstrate significant recent progress in hypervelocity atmospheric transit and hardening of launch vehicle components to withstand higher launch accelerators by several orders of magnitude. It is noted that these recent advances have significant impact on the payload which can be placed in orbit and have a major influence on the onboard propulsion requirements for orbit insertion. Based on technical achievements in all the critical supporting technologies, it is concluded that it is now feasible to demonstrate a credible electromagnet Earth-to-space launch system
Electromagnetic Launch: Highway to the Stars
(1987-09) Fair, H. D.; Meinel, C; Parks, K.
The future of large-scale space industrialization is considered and the key role of Earth-to-space electromagnetic launch is projected. The energetic relationships of the orbits of cislunar space and trajectories are outlined so as to set the stage for understanding requirements of' an Earth-to-space launcher. Historical analogies of the progression and maturation of transportation technologies are given: Ming Dynasty vs. Portuguese and Spanish navies in 15th century; C&O Canal vs. B&O Railroad in 19th century. Evidence is given that today's chemically propelled Earth-to-space launch is now a mature technology unlikely to yield to further major reductions in cost or increases in performance. The underlying factor behind the seemingly premature plateau in rocket technology is identified: performance in even the ultimate theoretical ideal is an exponential function of both the specific impulse of the fuel and the kinetic energy change required. Electromagnetic launch as an alternative is examined. A point design is presented of an Earth-to-space electromagnetic launcher which approaches ideal efficiency: a superconductor quench launch of a high-ballistic-coefficient vehicle. Examples are calculated of how given muzzle velocities and vehicle ballistic coefficients translate into orbits and payloads attained. This design exercise identifies required enabling technologies and the research efforts now underway which may lead to desirable superconductors and vehicle structural/heat shield materials in the near future.
Eric Berger, B.A. Astronomy, '95
(The Texas Scientist, 2019) The Texas Scientist
Five-Year Wilkinson Microwave Anisotropy Probe Observations: Angular Power Spectra
(2009-02) Nolta, M. R.; Dunkley, J.; Hill, R. S.; Hinshaw, G.; Komatsu, Eiichiro; Larson, D.; Page, L.; Spergel, D. N.; Bennett, C. L.; Gold, B.; Jarosik, N.; Odegard, N.; Weiland, J. L.; Wollack, E.; Halpern, M.; Kogut, A.; Limon, M.; Meyer, S. S.; Tucker, G. S.; Wright, E. L.; Komatsu, Eiichiro
We present the temperature and polarization angular power spectra of the cosmic microwave background derived from the first five years of Wilkinson Microwave Anisotropy Probe data. The five-year temperature spectrum is cosmic variance limited up to multipole l = 530, and individual l-modes have signal-to-noise ratio S/N > 1 for l < 920. The best-fitting six-parameter Lambda CDM model has a reduced chi(2) for l = 33-1000 of chi(2)/nu = 1.06, with a probability to exceed of 9.3%. There is now significantly improved data near the third peak which leads to improved cosmological constraints. The temperature-polarization correlation is seen with high significance. After accounting for foreground emission, the low-l reionization feature in the EE power spectrum is preferred by Delta chi(2) = 19.6 for optical depth tau = 0.089 by the EE data alone, and is now largely cosmic variance limited for l = 2-6. There is no evidence for cosmic signal in the BB, TB, or EB spectra after accounting for foreground emission. We find that, when averaged over l = 2-6, l(l + 1)CBB(l)(BB)/(2 pi) < 0.15 mu K(2) (95% CL).
Flywheel Batteries for Vehicles
(2002-06) Beno, J.H.; Thompson, R.C; Hebner, R.E.
Energy storage flywheels are useful in power conditioning applications, i.e. when there is a mismatch between the power generated and the power required by the load. Two examples of this mismatch are a temporal mismatch and a mismatch in magnitude. The use of a flywheel in a hybrid vehicle, for example, permits the engine to be designed to provide only the power needed to overcome steadystate losses and not have the inefficiencies that result when the engine must also provide power for maximum acceleration. While power management has provided the opportunities for flywheel batteries in vehicles, advances in technology have made the systems more practical. The key advance is the development of very high strength, long-life composites. These materials have significantly improved the energy density in the system over what could be achieved with a steel wheel by permitting much higher rotational velocities. So, smaller, lighter wheels can store energy in the range from less than a kilowatt-hour to more than 100 kilowatt-hours. Other important advances have been in magnetic bearings that allow reliable high-speed operation and in power electronics to control the output power. Vehicular operation does produce new issues that were less significant in the more traditional stationary applications. One of the most obvious among these is torque management. In charging or discharging a flywheel, the rotational velocity is changed and a torque is produced. For example, systems intended for the International Space Station, where torque management is critical, the initial plan is to cancel torque by using two counter-rotating flywheels. Once confidence is gained in this mode of operation, energy will be distributed among various flywheels to produce the net torque needed for stable operation. For terrestrial vehicles, the flywheel is in a gimbled compliant mount with the axis of rotation orthogonal to the plane of vehicle motion. This orientation permits torque to be compensated by the magnetic bearings and the mount. Tests show that the mount and bearing system can accommodate the shock and vibrations, as well as traveling up or down grades, expected under on-road operation.
Hydroburst testing for filament wound composites
(ICCE, 2001-08) Thompson, R.C.; Rech, B.M; Pak, T.T.
Lecture 1, part 1: the railway station: a tower of babel
(2009-09-28) Kohler, Niklaus
Dr. Kohler looks at the railway station's importance in 19th century Europe in terms of its impact on social interaction, people's concepts of time, and economic and technological change. Over the years, the railway station's role has diminished to the point that it has been called an "endangered species".
Lecture 1, part 2: foundations of sustainable design: railway stations between place and node
(2009-09-28) Kohler, Niklaus
Dr. Kohler presents a discussion of the concepts of space, place, and nodes, and how these concepts play into our notions of urban environment and transportation design.
Lecture 1, part 3: railway stations: the power of place
(2009-09-28) Kohler, Niklaus
Dr. Kohler presents images of railway stations around the world to provide context for considering railway station design.
Lecture 1: introduction
(2009-09-28) Kohler, Niklaus
In his Introduction, Dr. Kohler presents a brief overview of his research and ideas, gives an outline of the seminar and its objectives, and discusses the fundamental concepts that inform the seminar's approach to sustainable architectural design: space, place, nodes, time, and flows.
The Lick AGN Monitoring Project 2011: Fe II Reverberation From The Outer Broad-Line Region
(2013-06) Barth, Aaron J.; Pancoast, Anna; Bennert, Vardha N.; Brewer, Brendon J.; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor L.; Greene, Jenny E.; Li, Weidong; Malkan, Matthew A.; Sand, David J.; Stern, Daniel; Treu, Tommaso; Woo, Jong-Hak; Assef, Roberto J.; Bae, Hyun-Jin; Buehler, Tabitha; Cenko, S. Bradley; Clubb, Kelsey I.; Cooper, Michael C.; Diamond-Stanic, Aleksandar M.; Hoenig, Sebastian F.; Joner, Michael D.; Laney, C. David; Lazarova, Mariana S.; Nierenberg, A. M.; Silverman, Jeffrey M.; Tollerud, Erik J.; Walsh, Jonelle L.; Silverman, Jeffrey M.; Walsh, Jonelle L.
The prominent broad Fe II emission blends in the spectra of active galactic nuclei have been shown to vary in response to continuum variations, but past attempts to measure the reverberation lag time of the optical Fe II lines have met with only limited success. Here we report the detection of Fe II reverberation in two Seyfert 1 galaxies, NGC 4593 and Mrk 1511, based on data from a program carried out at Lick Observatory in Spring 2011. Light curves for emission lines including H beta and Fe II were measured by applying a fitting routine to decompose the spectra into several continuum and emission-line components, and we use cross-correlation techniques to determine the reverberation lags of the emission lines relative to V-band light curves. In both cases, the measured lag (tau(cen)) of Fe II is longer than that of H beta, although the inferred lags are somewhat sensitive to the choice of Fe II template used in the fit. For spectral decompositions done using the Fe II template of Veron-Cetty et al., we find tau(cen)(Fe II)/tau(cen)(H beta) = 1.9 +/- 0.6 in NGC 4593 and 1.5 +/- 0.3 in Mrk 1511. The detection of highly correlated variations between Fe II and continuum emission demonstrates that the Fe II emission in these galaxies originates in photoionized gas, located predominantly in the outer portion of the broad-line region.
Musk, Branson, Bezos, and the New Space Race
(2019-03-11) Aufiero, Nicholas
Presentation: Space Exploration: From Science Fiction to the Texas Spacecraft Laboratory
(Environmental Science Institute, 2014-03-01) Lightsey, Glenn; Environmental Science Institute
Printed Materials and Their Effects on Quasi-Optical Millimeter Wave Guide Lens Systems
(University of Texas at Austin, 2019) Foster, Diana; Corey, Chris; Fisher, Chris; Smith, Caitlin; Paolella, Arthur
This study of 3D printed quasi-optical (Q-O) millimeter wave guide lens systems is presented in three phases: the characterization of 3D printed materials for radio frequency (RF) applications and systems; the development and demonstration of 3D printing technology for RF systems; and the design process, simulation, fabrication, and testing of RF lens systems. The first phase explores the ability to print high-quality materials with fine resolution and the determination of each material’s dielectric constant and loss tangent. The second phase details the development of dual biconvex shaped lens systems and the resulting test data. The third phase combines the former stages’ results to model, print, and test a set of lenses pre-aligned with an integrated support structure. These lens systems were tested up to 100 GHz with demonstrated focusing gain of 22.1 dB.
Regular Frequency Patterns In The Classical Delta Scuti Star HD 144277 Observed By The MOST Satellite
(2011-09) Zwintz, K.; Lenz, P.; Breger, M.; Pamyatnykh, A. A.; Zdravkov, T.; Kuschnig, R.; Matthews, J. M.; Guenther, D. B.; Moffat, A. F. J.; Rowe, J. F.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.; Breger, M.
Context. We present high-precision time-series photometry of the classical delta Scuti star HD 144277 obtained with the MOST (Microvariability and Oscillations of STars) satellite in two consecutive years. The observed regular frequency patterns are investigated asteroseismologically. Aims. HD 144277 is a hot A-type star that is located on the blue border of the classical instability strip. While we mostly observe low radial order modes in classical delta Scuti stars, HD 144277 presents a different case. Its high observed frequencies, i.e., between 59.9 d(-1) (693.9 mu Hz) and 71.1 d(-1) (822.8 mu Hz), suggest higher radial orders. We examine the progression of the regular frequency spacings from the low radial order to the asymptotic frequency region. Methods. Frequency analysis was performed using Period04 and SigSpec. The results from the MOST observing runs in 2009 and 2010 were compared to each other. The resulting frequencies were submitted to asteroseismic analysis. Results. HD 144277 was discovered to be a delta Scuti star using the time-series photometry observed by the MOST satellite. Twelve independent pulsation frequencies lying in four distinct groups were identified. Two additional frequencies were found to be combination frequencies. The typical spacing of 3.6 d(-1) corresponds to the spacing between subsequent radial and dipole modes, therefore the spacing between radial modes is twice this value, 7.2 d(-1). Based on the assumption of slow rotation, we find evidence that the two radial modes are the sixth and seventh overtones, and the frequency with the highest amplitude can be identified as a dipole mode. Conclusions. The models required to fit the observed instability range need slightly less metallicity and a moderate enhancement of the helium abundance compared to the standard chemical composition. Our asteroseismic models suggest that HD 144277 is a delta Scuti star close to the ZAMS with a mass of 1.66 M(circle dot).
Regular Frequency Patterns In The Young Delta Scuti Star HD 261711 Observed By The CoRoT And MOST Satellites
(2013-04) Zwintz, K.; Fossati, L.; Guenther, D. B.; Ryabchikova, T.; Baglin, A.; Themessl, N.; Barnes, T. G.; Matthews, J. M.; Auvergne, M.; Bohlender, D.; Chaintreuil, S.; Kuschnig, R.; Moffat, A. F. J.; Rowe, J. F.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.; Barnes, T. G.
Context. The internal structure of pre-main-sequence (PMS) stars is poorly constrained at present. This could change significantly through high-quality asteroseismological observations of a sample of such stars. Aims. We concentrate on an asteroseismological study of HD261711, a rather hot delta Scuti-type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD261711 was discovered to be a PMS delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. Methods. High-precision, time-series photometry of HD261711 was obtained by the MOST and CoRoT satellites in four separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. Frequency Analysis was performed using Period04. The spectral analysis was performed using equivalent widths and spectral synthesis. Results. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the delta Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new delta Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group were determined and are related to l = 0 and l = 1 p-modes. Evidence for amplitude modulation of the frequencies in two groups is seen. The effective temperature (T-eff) was derived to be 8600 +/- 200K, log g is 4.1 +/- 0.2, and the projected rotational velocity (upsilon sin i) is 53 +/- 1 km s(-1). Using our T-eff value and the radius of 1.8 +/- 0.5 R-circle dot derived from spectral energy distribution (SED) fitting, we get a luminosity log L/L-circle dot of 1.20 +/- 0.14 which agrees well to the seismologically determined values of 1.65 R-circle dot and, hence, a log L/L-circle dot of 1.13. The radial velocity of 14 +/- 2 km s(-1) we derived for HD261711, confirms the star's membership to NGC 2264. Conclusions. Our asteroseismic models suggest that HD261711 is a delta Scuti-type star close to the zero-age main sequence (ZAMS) with a mass of 1.8 to 1.9 M-circle dot. With an age of about 10 million years derived from asteroseismology, the star is either a young ZAMS star or a late PMS star just before the onset of hydrogen-core burning. The observed splittings about the l = 0 and 1 parent modes may be an artifact of the Fourier derived spectrum of frequencies with varying amplitudes.
Regular Frequency Patterns In The Young Delta Scuti Star HD 261711 Observed By The CoRoT And MOST Satellites
(2013-04) Zwintz, K.; Fossati, L.; Guenther, D. B.; Ryabchikova, T.; Baglin, A.; Themessl, N.; Barnes, T. G.; Matthews, J. M.; Auvergne, M.; Bohlender, D.; Chaintreuil, S.; Kuschnig, R.; Moffat, A. F. J.; Rowe, J. F.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.; Barnes, T. G.
Context. The internal structure of pre-main-sequence (PMS) stars is poorly constrained at present. This could change significantly through high-quality asteroseismological observations of a sample of such stars. Aims. We concentrate on an asteroseismological study of HD261711, a rather hot delta Scuti-type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD261711 was discovered to be a PMS delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. Methods. High-precision, time-series photometry of HD261711 was obtained by the MOST and CoRoT satellites in four separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. Frequency Analysis was performed using Period04. The spectral analysis was performed using equivalent widths and spectral synthesis. Results. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the delta Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new delta Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group were determined and are related to l = 0 and l = 1 p-modes. Evidence for amplitude modulation of the frequencies in two groups is seen. The effective temperature (T-eff) was derived to be 8600 +/- 200K, log g is 4.1 +/- 0.2, and the projected rotational velocity (upsilon sin i) is 53 +/- 1 km s(-1). Using our T-eff value and the radius of 1.8 +/- 0.5 R-circle dot derived from spectral energy distribution (SED) fitting, we get a luminosity log L/L-circle dot of 1.20 +/- 0.14 which agrees well to the seismologically determined values of 1.65 R-circle dot and, hence, a log L/L-circle dot of 1.13. The radial velocity of 14 +/- 2 km s(-1) we derived for HD261711, confirms the star's membership to NGC 2264. Conclusions. Our asteroseismic models suggest that HD261711 is a delta Scuti-type star close to the zero-age main sequence (ZAMS) with a mass of 1.8 to 1.9 M-circle dot. With an age of about 10 million years derived from asteroseismology, the star is either a young ZAMS star or a late PMS star just before the onset of hydrogen-core burning. The observed splittings about the l = 0 and 1 parent modes may be an artifact of the Fourier derived spectrum of frequencies with varying amplitudes.
Regular Frequency Patterns In The Young Delta Scuti Star HD 261711 Observed By The CoRoT And MOST Satellites
(2013-04) Zwintz, K.; Fossati, L.; Guenther, D. B.; Ryabchikova, T.; Baglin, A.; Themessl, N.; Barnes, T. G.; Matthews, J. M.; Auvergne, M.; Bohlender, D.; Chaintreuil, S.; Kuschnig, R.; Moffat, A. F. J.; Rowe, J. F.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.; Barnes, T. G.
Context. The internal structure of pre-main-sequence (PMS) stars is poorly constrained at present. This could change significantly through high-quality asteroseismological observations of a sample of such stars. Aims. We concentrate on an asteroseismological study of HD261711, a rather hot delta Scuti-type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD261711 was discovered to be a PMS delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. Methods. High-precision, time-series photometry of HD261711 was obtained by the MOST and CoRoT satellites in four separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. Frequency Analysis was performed using Period04. The spectral analysis was performed using equivalent widths and spectral synthesis. Results. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the delta Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new delta Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group were determined and are related to l = 0 and l = 1 p-modes. Evidence for amplitude modulation of the frequencies in two groups is seen. The effective temperature (T-eff) was derived to be 8600 +/- 200K, log g is 4.1 +/- 0.2, and the projected rotational velocity (upsilon sin i) is 53 +/- 1 km s(-1). Using our T-eff value and the radius of 1.8 +/- 0.5 R-circle dot derived from spectral energy distribution (SED) fitting, we get a luminosity log L/L-circle dot of 1.20 +/- 0.14 which agrees well to the seismologically determined values of 1.65 R-circle dot and, hence, a log L/L-circle dot of 1.13. The radial velocity of 14 +/- 2 km s(-1) we derived for HD261711, confirms the star's membership to NGC 2264. Conclusions. Our asteroseismic models suggest that HD261711 is a delta Scuti-type star close to the zero-age main sequence (ZAMS) with a mass of 1.8 to 1.9 M-circle dot. With an age of about 10 million years derived from asteroseismology, the star is either a young ZAMS star or a late PMS star just before the onset of hydrogen-core burning. The observed splittings about the l = 0 and 1 parent modes may be an artifact of the Fourier derived spectrum of frequencies with varying amplitudes.
Revisiting “Black Downtown”: Spatial and Storytelling Practices in Austin, Texas
(2020-05) Mata, Ryan Andrew; Campbell, Craig
Harrison David Eppright, a multi-generational black artist, creates and participates in an everyday performance of culture and visibility through his capacity as a tour guide for the city and an ambassador for Austin’s visitor services. Harrison has a unique subjective experience affected by intersecting identities and oppressions, including those along the lines of race and sexuality. I examine how he assigns meaning to places that are fading, getting bulldozed, or enduring. This thesis explores how Harrison utilizes storytelling and walking tours in the shifting landscape of East Austin in order to find pride in “home” while making visible the cultural makeup being threatened by current circumstances such as gentrification and displacement. These neighborhoods in Austin, which were once designed as a “negro district”, now face the problem of losing their identity to a host of new development that has led to the pricing-out and displacement of mostly black and brown working-class residents and businesses.