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1

Optimal nadir scan angle for a space-based Doppler lidar wind sounder  

NASA Technical Reports Server (NTRS)

A Laser Atmospheric Wind Sounder computer simulation model was used to conduct a series of trades between scan angle and accuracy/coverage to determine the optimal scan angle for a space-based Doppler lidar wind sounder. Attention is given to vertical backscatter profiles, advanced signal processing, pulse length, shot density, and vertical velocity variance. The LOS speed uncertainty (m/s) projected into the horizontal plane as a function of the nadir scan angle for a single laser shot into the upper troposphere and lowest 1 km of the earth's atmosphere for expected backscatter values is shown.

Emmitt, George D.

1991-01-01

2

Sensitivity of MODIS 2.1 micron Channel for Off-Nadir View Angles for Use in Remote Sensing of Aerosol  

NASA Technical Reports Server (NTRS)

Remote sensing of aerosol over land, from MODIS will be based on dark targets using mid-IR channels 2.1 and 3.9 micron. This approach was developed by Kaufman et al (1997), who suggested that dark surface reflectance in the red (0.66 micron -- rho(sub 0.66)) channel is half of that at 2.2 micron (rho(sub 2.2)), and the reflectance in the blue (0.49 micron - rho(sub 0.49)) channel is a quarter of that at 2.2 micron. Using this relationship, the surface reflectance in the visible channels can be predicted within Delta.rho(sub 0.49) approximately Delat.rho(sub 0.66) approximately 0.006 from rho(sub 2.2) for rho(sub 2.2) <= 0.10. This was half the error obtained using the 3.75 micron and corresponds to an error in aerosol optical thickness of Delat.tau approximately 0.06. These results, though applicable to several biomes (e.g. forests, and brighter lower canopies), have only been tested at one view angle - the nadir (theta = 0 deg). Considering the importance of the results in remote sensing of aerosols over land surfaces from space, we are validating the relationships for off-nadir view angles using Cloud Absorption Radiometer (CAR) data. The CAR data are available for channels between 0.3 and 2.3 micron and for different surface types and conditions: forest, tundra, ocean, sea-ice, swamp, grassland and over areas covered with smoke. In this study we analyzed data collected during the Smoke, Clouds, and Radiation - Brazil (SCAR-B) experiment to validate Kaufman et al.'s (1997) results for non-nadir view angles. We will show the correlation between rho(sub 0.472), rho(sub 0.675), and rho(sub 2.2) for view angles between nadir (0 deg) and 55 deg off-nadir, and for different viewing directions in the backscatter and forward scatter directions.

Gatebe, C. K.; King, M. D.; Tsay, S.-C.; Ji, Q.

2000-01-01

3

Optimal nadir scan angle for a space-based Doppler lidar wind sounder  

Microsoft Academic Search

A Laser Atmospheric Wind Sounder computer simulation model was used to conduct a series of trades between scan angle and accuracy\\/coverage to determine the optimal scan angle for a space-based Doppler lidar wind sounder. Attention is given to vertical backscatter profiles, advanced signal processing, pulse length, shot density, and vertical velocity variance. The LOS speed uncertainty (m\\/s) projected into the

George D. Emmitt

1991-01-01

4

Obesity, Prostate-Specific Antigen Nadir, and Biochemical Recurrence After Radical Prostatectomy: Biology or Technique? Results from the SEARCH Database  

PubMed Central

Background Obesity is associated with an increased risk of biochemical recurrence (BCR) after radical prostatectomy (RP). It is unclear whether this is due to technical challenges related to operating on obese men or other biologic factors. Objective To examine whether obesity predicts higher prostate-specific antigen (PSA) nadir (as a measure of residual PSA-producing tissue) after RP and if this accounts for the greater BCR risk in obese men. Design, setting, and participants A retrospective analysis of 1038 RP patients from 2001 to 2010 in the multicenter US Veterans Administration–based Shared Equal Access Regional Cancer Hospital database with median follow-up of 41 mo. Intervention All patients underwent RP. Outcome measurements and statistical analysis We evaluated the relationship between body mass index (BMI) and ultrasensitive PSA nadir within 6 mo after RP. Adjusted proportional hazards models were used to examine the association between BMI and BCR with and without PSA nadir. Results and limitations Mean BMI was 28.5 kg/m2. Higher BMI was associated with higher PSA nadir on both univariable (p = 0.001) and multivariable analyses (p < 0.001). Increased BMI was associated with increased BCR risk (hazard ratio [HR]: 1.06; p = 0.007). Adjusting for PSA nadir slightly attenuated, but did not eliminate, this association (HR: 1.04, p = 0.043). When stratified by PSA nadir, obesity only significantly predicted BCR in men with an undetectable nadir (p = 0.006). Unfortunately, other clinically relevant end points such as metastasis or mortality were not available. Conclusions Obese men are more likely to have a higher PSA nadir, suggesting that either more advanced disease or technical issues confound an ideal operation. However, even after adjusting for the increased PSA nadir, obesity remained predictive of BCR, suggesting that tumors in obese men are growing faster. This provides further support for the idea that obesity is biologically associated with prostate cancer progression.

Ho, Tammy; Gerber, Leah; Aronson, William J.; Terris, Martha K.; Presti, Joseph C.; Kane, Christopher J.; Amling, Christopher L.; Freedland, Stephen J.

2012-01-01

5

New results on drawing angle graphs  

Microsoft Academic Search

An angle graph is a graph with a fixed cyclic order of the edges around each vertex and an angle specified for every pair of consecutive edges incident on a vertex. We study the problem of constructing a drawing of an angle graph that preserves its angles, and present several new results. •• We disprove the conjectures of Vijayan (1986)

Ashim Garg

1998-01-01

6

Nadir Measurements of Carbon Monoxide Distributions by the Tropospheric Emission Spectrometer Instrument Onboard the Aura Spacecraft: Overview of Analysis Approach and Examples of Initial Results  

NASA Technical Reports Server (NTRS)

We provide an overview of the nadir measurements of carbon monoxide (CO) obtained thus far by the Tropospheric Emission Spectrometer (TES). The instrument is a high resolution array Fourier transform spectrometer designed to measure infrared spectral radiances from low Earth orbit. It is one of four instruments successfully launched onboard the Aura platform into a sun synchronous orbit at an altitude of 705 km on July 15, 2004 from Vandenberg Air Force Base, California. Nadir spectra are recorded at 0.06/cm spectral resolution with a nadir footprint of 5 x 8 km. We describe the TES retrieval approach for the analysis of the nadir measurements, report averaging kernels for typical tropical and polar ocean locations, characterize random and systematic errors for those locations, and describe instrument performance changes in the CO spectral region as a function of time. Sample maps of retrieved CO for the middle and upper troposphere from global surveys during December 2005 and April 2006 highlight the potential of the results for measurement and tracking of global pollution and determining air quality from space.

Rinsland, Curtis P.; Luo, Ming; Logan, Jennifer A.; Beer, Reinhard; Worden, Helen; Kulawik, Susan S.; Rider, David; Osterman, Greg; Gunson, Michael; Eldering, Annmarie; Goldman, Aaron; Shephard, Mark; Clough, Shepard A.; Rodgers, Clive; Lampel, Michael; Chiou, Linda

2006-01-01

7

First results from a rotational Raman scattering cloud algorithm applied to the Suomi National Polar-orbiting Partnership (NPP) Ozone Mapping Profiler Spectrometer (OMPS) nadir mapper  

NASA Astrophysics Data System (ADS)

This paper reports initial results from an Ozone Mapping Profiler Suite (OMPS) nadir mapper cloud pressure and cloud fraction algorithm. The OMPS cloud products are intended for use in OMPS ozone or other trace-gas algorithms. We developed the OMPS cloud products using a heritage algorithm developed for the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite. The cloud pressure algorithm utilizes the filling-in of ultra-violet solar Fraunhofer lines by rotational Raman scattering. The OMPS cloud products are evaluated by comparison with OMI cloud products that have been compared in turn with other collocated satellite data including cloud optical thickness profiles derived from a combination of measurements from the CloudSat radar and the MODIS imaging radiometer. We find that the probability density functions (PDFs) of effective cloud fraction retrieved from OMPS and OMI measurements are very similar. The PDFs of the OMPS and OMI cloud pressures are comparable. However, OMPS retrieves somewhat higher pressures on average. The current NASA total ozone retrieval algorithm makes use of a monthly gridded cloud pressure climatology developed from OMI. This climatology captures much of the variability associated with the relevant cloud pressures. However, the use of actual cloud pressures retrieved with OMPS in place of the OMI climatology appears to improve OMPS total column ozone estimates slightly.

Vasilkov, A.; Joiner, J.; Seftor, C.

2014-03-01

8

Nadir measurements of carbon monoxide distributions by the Tropospheric Emission Spectrometer instrument onboard the Aura Spacecraft: Overview of analysis approach and examples of initial results  

Microsoft Academic Search

We provide an overview of the nadir measurements of carbon monoxide (CO) obtained thus far by the Tropospheric Emission Spectrometer (TES). The instrument is a high resolution array Fourier transform spectrometer designed to measure infrared spectral radiances from low Earth orbit. It is one of four instruments successfully launched onboard the Aura platform into a sun synchronous orbit at an

Curtis P. Rinsland; Ming Luo; Jennifer A. Logan; Reinhard Beer; Helen Worden; Susan S. Kulawik; David Rider; Greg Osterman; Michael Gunson; Annmarie Eldering; Aaron Goldman; Mark Shephard; Shepard A. Clough; Clive Rodgers; Michael Lampel; Linda Chiou

2006-01-01

9

Angles  

NSDL National Science Digital Library

Play these games to determine the best angles for success! Alien Angles Set the angle to rescue the alien. Space Angles Target the angle to shoot the alien spaceship. Mini Golf Knowing the angles will help you get the ball in the hole. ...

Clark, Mr

2012-10-31

10

Nadir PSA level and time to nadir PSA are prognostic factors in patients with metastatic prostate cancer  

PubMed Central

Background Primary androgen deprivation therapy (PADT) is the most effective systemic therapy for patients with metastatic prostate cancer. Nevertheless, once PSA progression develops, the prognosis is serious and mortal. We sought to identify factors that predicted the prognosis in a series of patients with metastatic prostate cancer. Methods Two-hundred eighty-six metastatic prostate cancer patients who received PADT from 1998 to 2005 in Nara Uro-Oncology Research Group were enrolled. The log-rank test and Cox’s proportional hazards model were used to determine the predictive factors for prognosis; rate of castration-resistant prostate cancer (CRPC) and overall survival. Results The median age, follow-up period and PSA level at diagnosis were 73 years, 47 months and 174 ng/mL, respectively. The 5-year overall survival rate was 63.0%. The multivariable analysis showed that Gleason score (Hazard ratio [HR]:1.362; 95% confidence interval [C.I.], 1.023-1.813), nadir PSA (HR:6.332; 95% C.I., 4.006-9.861) and time from PADT to nadir (HR:4.408; 95% C.I., 3.099-6.271) were independent prognostic factors of the incidence of CRPC. The independent parameters in the multivariate analysis that predicted overall survival were nadir PSA (HR:5.221; 95% C.I., 2.757-9.889) and time from PADT to nadir (HR:4.008; 95% C.I., 2.137-7.517). Conclusions Nadir PSA and time from PADT to nadir were factors that affect both CRPC and overall survival in a cohort of patients with metastatic prostate cancer. Lower nadir PSA level and longer time from PADT to nadir were good for survival and progression.

2014-01-01

11

Angles  

NSDL National Science Digital Library

This set of eight interactive activities lets the user explore angles from many different perspectives. Activities include (1) visualizing the size of an angle; (2) examining objects that will stand or fall with right and non-right angles; (3) identifying obtuse, right, acute and straight angles; (4) guessing angle measures with different levels of precision; (5) exploring regular shapes and their angle measures; (6) studying angles in a fractal tree that is drawn with user inputs of the same angle measure between the branches at each stage; (7) exploring angle measures through firing a cannon (8) drawing with a Logo activity.

Edkins, Jo

2007-01-01

12

Angles.  

National Technical Information Service (NTIS)

Shows the Brownstone Kids teaching others how to dance. Illustrates angles as they turn and sing 'Get the Angles.' The group goes to a community center for playing pool in 'Calling Shoots.' Discusses angles showing the 90-degree, 45-degree, and 180-degree...

1994-01-01

13

Inferring hemispherical reflectance of the earth's surface for global energy budgets from remotely sensed nadir or directional radiance values  

NASA Technical Reports Server (NTRS)

The relationship between directional reflectances spanning the entire reflecting hemisphere and hemispherical reflectance (albedo) and the effect of solar zenith angle and cover type on these relationships were investigated, using the results obtained from NOAA's 7/8 AVHRR ground-level reflectance measurements. Bands 1 (0.58-0.6B microns) and 2 (0.73-1. 1 microns) were used for reflectance measurements of 11 natural vegetation surfaces ranging from bare soils to dense vegetation canopies. The results show that errors in inferring hemispherical reflectance from nadir reflectance can be between 11 and 45 percent for all cover types and solar angles, depending on the viewing angles. A technique is described in which a choice of two specific view angles reduces this error to less than 6 percent for both bands and for all sun angles and cover types.

Kimes, D. S.; Sellers, P. J.

1985-01-01

14

Correction of Sampling Errors in Ocean Surface Cross-Sectional Estimates from Nadir-Looking Weather Radar  

NASA Technical Reports Server (NTRS)

The return from the ocean surface has a number of uses for airborne meteorological radar. The normalized surface cross section has been used for radar system calibration, estimation of surface winds, and in algorithms for estimating the path-integrated attenuation in rain. However, meteorological radars are normally optimized for observation of distributed targets that fill the resolution volume, and so a point target such as the surface can be poorly sampled, particularly at near-nadir look angles. Sampling the nadir surface return at an insufficient rate results in a negative bias of the estimated cross section. This error is found to be as large as 4 dB using observations from a high-altitude airborne radar. An algorithm for mitigating the error is developed that is based upon the shape of the surface echo and uses the returned signal at the three range gates nearest the peak surface echo.

Caylor, I. Jeff; Meneghini, R.; Miller, L. S.; Heymsfield, G. M.

1997-01-01

15

Results from the G0 forward angle measurement  

SciTech Connect

The results from the G0 forward angle experiment are reported in this talk. The parity-violating asymmetry of elastic e-p scattering has been measured within the range of the four-momentum transfer (Q2) from 0.12 to 1.0 (GeV/c)2, which yields linear combinations of the strange electric and magnetic form factors of the nucleon, G{sub E}{sup s} + etaG{sub M}{sup s}, in the same Q2 range. The G0 results, combined with the measurements from other experiments, indicate that G{sub E}{sup s} and G{sub M}{sup s} are both likely non-zero.

J. Liu

2006-07-01

16

OSRMS: The DREP Near-Nadir Scatterometer.  

National Technical Information Service (NTIS)

The ocean surface roughness measurement system (OSRMS) is a near-nadir directed infrared (IR) scatterometer specially constructed for and operated by the Defence Research Establishment Pacific (DREP). It has been used to measure ocean surface parameters a...

L. C. Rempel B. A. Hughes S. J. Hughes

1988-01-01

17

Dust aerosol retrieval results from MISR (multi-angle imaging spectro-radiometer)  

NASA Technical Reports Server (NTRS)

Satellite measurements provide important tools for understanding the effect of mineral dust aerosols on past and present climate and climate predictions. Multi-angle instruments such as Multi-angle Imaging Spectro- Radiometer (MISR) provide independent constraints on aerosol properties based on their sensitivity to the shape of aerosol scattering phase functions. The current MISR operational retrieval algorithm (version 16 and higher) was modified by incorporating new non-spherical dust models that account for naturally occurring dust shapes and compositions. We present selected examples of MISR version 16 retrievals over AERONET sunphotometer land and ocean sites during the passage of dust fronts. Our analysis shows that during such events MISR retrieves Angstrom exponents characteristic of large particles, having little spectral variation in extinction over the MISR wavelength range (442, 550, 672 and 866 nm channels), as expected. The retrieved fraction of non-spherical particles is also very high. This quantity is not retrieved by satellite instruments having only nadir-viewing cameras. Our comparison of current (version 16) MISR-retrieved aerosol optical thickness (AOT) with AERONET instantaneous AOT shows better coverage and stronger correlations than when making identical comparisons with previous AOT retrievals (version 15). The MISR algorithm successful mixtures include a non-spherical dust component with high frequency in retrievals over dark water and slightly lower frequency over land. Selection frequencies of non-spherical dust models also decrease in dusty regions affected by pollution.

Kalashnikova, Olga V.; Diner, David J.; Kahn, Ralph; Gaitley, Barbara

2004-01-01

18

Angled Injection: Turbulent Flow Hybrid Bearings Comparison to Test Results  

NASA Technical Reports Server (NTRS)

Hydrostatic/hydrodynamic (hybrid) journal bearings handling process liquids have limited dynamic stability characteristics and their application as support elements to high speed flexible rotating systems is severely restricted. Measurements on water hybrid bearings with angled orifice injection have demonstrated improved rotordynamic performance with virtual elimination of cross-coupled stiffness coefficients and null or negative whirl frequency ratios. A bulk-flow model for prediction of the static performance and force coefficients of hybrid bearings with angled orifice injection is advanced. The analysis reveals that the fluid momentum exchange at the orifice discharge produces a pressure rise in the hydrostatic recess retards the shear flow induced by journal rotation, and thus, reduces cross-coupling forces. The predictions from the model are compared with experimental measurements for a 45 deg. angled orifice injection, 5 recess water hybrid bearing operating at 10.2, 17.4, and 24.6 krpm and with supply pressures of 4, 5.5, and 7 MPa. The correlations include recess pressures, flow rates, and rotordynamic force coefficients at the journal centered position.

SanAndres, Luis; Childs, Dara

1997-01-01

19

S-NPP OMPS Nadir Performance and Calibration  

NASA Astrophysics Data System (ADS)

This presentation analyzes the in-flight performance of the S-NPP OMPS Nadir instruments and evaluates sensors' on-orbit calibrations. During the past two year, OMPS has collected all types of orbital calibration and science data that have allowed us to better understand the two Nadir sensors' on-orbit performances, and consequently to establish the baseline calibrations during the early orbital checkout and intensive calibration and validation of the instruments. This presentation evaluates the orbital sensors' performances and verifies the orbital calibration. From studies that we have conducted so far since the sensor launch,the largest term in the sensor calibration uncertainty is the wavelength shift effect of 0.15 nm when the sensor transitioned from ground to orbit. Our results have also demonstrated that sensor on-orbit performance complies with the system specifications, while the final adjustments of stray-light correction are still being made to optimize OMPS Sensor Data Records (SDRs).

Pan, Sherry; Wu, Fred

2014-05-01

20

Near-Nadir Radar Backscatter From Ocean Waves  

NASA Technical Reports Server (NTRS)

Paper discusses aspects of theory of near-nadir radar backscatter from well-developed sea. Study contributed to development of new technique for determination of sea-state bias in satellite altimeter measurements. Paper questions assumptions, bringing accepted interpretation of nadir and near-nadir radar backscattering into doubt.

Glazman, Roman E.

1992-01-01

21

NADIR: A Flexible Archiving System Current Development  

NASA Astrophysics Data System (ADS)

The New Archiving Distributed InfrastructuRe (NADIR) is under development at the Italian center for Astronomical Archives (IA2) to increase the performances of the current archival software tools at the data center. Traditional softwares usually offer simple and robust solutions to perform data archive and distribution but are awkward to adapt and reuse in projects that have different purposes. Data evolution in terms of data model, format, publication policy, version, and meta-data content are the main threats to re-usage. NADIR, using stable and mature framework features, answers those very challenging issues. Its main characteristics are a configuration database, a multi threading and multi language environment C++, Java, Python), special features to guarantee high scalability, modularity, robustness, error tracking, and tools to monitor with confidence the status of each project at each archiving site. In this contribution, the development of the core components is presented, commenting also on some performance and innovative features (multi-cast and publisher-subscriber paradigms). NADIR is planned to be developed as simply as possible with default configurations for every project, first of all for LBT and other IA2 projects.

Knapic, C.; De Marco, M.; Smareglia, R.

2014-05-01

22

Bidirectional measurements of surface reflectance for view angle corrections of oblique imagery  

NASA Technical Reports Server (NTRS)

An apparatus for acquiring bidirectional reflectance-factor data was constructed and used over four surface types. Data sets were obtained over a headed wheat canopy, bare soil having several different roughness conditions, playa (dry lake bed), and gypsum sand. Results are presented in terms of relative bidirectional reflectance factors (BRFs) as a function of view angle at a number of solar zenith angles, nadir BRFs as a function of solar zenith angles, and, for wheat, vegetation indices as related to view and solar zenith angles. The wheat canopy exhibited the largest BRF changes with view angle. BRFs for the red and the NIR bands measured over wheat did not have the same relationship with view angle. NIR/Red ratios calculated from nadir BRFs changed by nearly a factor of 2 when the solar zenith angle changed from 20 to 50 degs. BRF versus view angle relationships were similar for soils having smooth and intermediate rough surfaces but were considerably different for the roughest surface. Nadir BRF versus solar-zenith angle relationships were distinctly different for the three soil roughness levels. Of the various surfaces, BRFs for gypsum sand changed the least with view angle (10 percent at 30 degs).

Jackson, R. D.; Teillet, P. M.; Slater, P. N.; Fedosejevs, G.; Jasinski, Michael F.

1990-01-01

23

Venus nitric oxide nightglow mapping from SPICAV nadir observations  

NASA Astrophysics Data System (ADS)

Nitric oxide ? (190-240 nm) and ? (255-270 nm) bands have been observed on the Venus nightside with Venus Express SPICAV instrument operated in the nadir mode. These ultraviolet emissions arise from the de-excitation of NO molecules created by radiative recombination of O(3P) and N(4S) atoms. These atoms are produced on the dayside of the planet through photodissociation of CO2 and N2 molecules and are transported to the nightside by the global subsolar to antisolar circulation. We analyze a wide dataset of nadir observations obtained since 2006 to determine the statistical distribution of the NO nightglow and its variability. Individual observations show a great deal of variability and may exhibit multiple maxima along latitudinal cuts. We construct and compare a global NO map with the results obtained during the Pioneer-Venus mission and with the recently observed O2(a1?g) nightglow distribution. The NO airglow distribution shows a statistical bright region extending from 01:00 to 03:30 local time and 25°S to 10°N, very similar to the Pioneer results obtained 35 years earlier during maximum solar activity conditions. The shift from the antisolar point and the difference with the O2 airglow indicate that superrotating zonal winds are statistically weak near 97 km, but play an important role near 115 km. We compare these results with other evidence for superrotation in the thermosphere and point out possible sources of momentum transfer.

Stiepen, A.; Gérard, J.-C.; Dumont, M.; Cox, C.; Bertaux, J.-L.

2013-09-01

24

Flight Test Results of an Angle of Attack and Angle of Sideslip Calibration Method Using Output-Error Optimization  

NASA Technical Reports Server (NTRS)

As part of a joint partnership between the NASA Aviation Safety Program (AvSP) and the University of Tennessee Space Institute (UTSI), research on advanced air data calibration methods has been in progress. This research was initiated to expand a novel pitot-static calibration method that was developed to allow rapid in-flight calibration for the NASA Airborne Subscale Transport Aircraft Research (AirSTAR) facility. This approach uses Global Positioning System (GPS) technology coupled with modern system identification methods that rapidly computes optimal pressure error models over a range of airspeed with defined confidence bounds. Subscale flight tests demonstrated small 2-s error bounds with significant reduction in test time compared to other methods. Recent UTSI full scale flight tests have shown airspeed calibrations with the same accuracy or better as the Federal Aviation Administration (FAA) accepted GPS 'four-leg' method in a smaller test area and in less time. The current research was motivated by the desire to extend this method for inflight calibration of angle of attack (AOA) and angle of sideslip (AOS) flow vanes. An instrumented Piper Saratoga research aircraft from the UTSI was used to collect the flight test data and evaluate flight test maneuvers. Results showed that the output-error approach produces good results for flow vane calibration. In addition, maneuvers for pitot-static and flow vane calibration can be integrated to enable simultaneous and efficient testing of each system.

Siu, Marie-Michele; Martos, Borja; Foster, John V.

2013-01-01

25

High elevation angle propagation results, applied to a statistical model and an enhanced empirical model  

NASA Astrophysics Data System (ADS)

The results of a recent narrowband propagation experiment at high elevation angles have been further analyzed to determine fit coefficient for the model proposed by Lutz et al. Results for the suburban and wooded environmental categories for elevation angles greater than 60 deg are reported. An empirical model for L and S bands covering elevation angles from 20 to 80 deg has been developed. The model combines the empirical roadside shadowing model, and the empirical fading model derived from the results of a narrowband propagation campaign, and improves the existing CCIR model.

Parks, M. A. N.; Evans, B. G.; Butt, G.

1993-09-01

26

Multiple emission angle surface–atmosphere separations of thermal emission spectrometer data  

Microsoft Academic Search

A method for separating the spectral signatures of the Martian surface and atmosphere was developed and is applied to multiple emission angle data returned from the MGS TES instrument. This method includes correlated-k and index gas removal algorithms that may be applied to all nadir-pointing TES data. Initial results have provided new and refined measurements of the spectral shapes of

Joshua L. Bandfield; Michael D. Smithb

2003-01-01

27

TES/Aura L2 Methanol Nadir (TL2MTLNS)  

TES/Aura L2 Methanol Nadir (TL2MTLNS) News:  TES News Join ... Level:  L2 Platform:  TES/Aura L2 Methanol Spatial Coverage:  5.3 x 8.5 km nadir ... OPeNDAP Access:  OPeNDAP Parameters:  Methanol Volume Mixing Ratio Precision Vertical Resolution Order ...

2013-11-06

28

TES/Aura L2 Methanol Nadir (TL2MTLN)  

TES/Aura L2 Methanol Nadir (TL2MTLN) News:  TES News Join TES ... Level:  L2 Platform:  TES/Aura L2 Methanol Spatial Coverage:  5.3 x 8.5 km nadir ... OPeNDAP Access:  OPeNDAP Parameters:  Methanol Volume Mixing Ratio Precision Vertical Resolution Order ...

2013-11-06

29

Assessing impacts of off-nadir observation on remote sensing of vegetation - Use of the Suits model  

NASA Technical Reports Server (NTRS)

The use of Suits' (1972a, b) digital radiative transfer model to simulate the effect of nonLambertian canopy reflectance on off-nadir observations of vegetation is discussed. Canopy reflectances of cord grass are calculated using the radiative transfer model, field radiometric measurements, and airborne multispectral scanner data. The effects of varying view angles on canopy reflectance are analyzed and compared. The comparison reveals that the model is effective in simulating the sense and magnitude of reflectance change due to variable angles of observations; however, the model does not reproduce the observed dependence of nadir canopy reflectance on solar zenith angle. It is concluded that the radiative transfer model is applicable for predicting the variation in canopy reflectance due to changing view zenith angles.

Bartlett, D. S.; Johnson, R. W.; Hardisky, M. A.; Klemas, V.

1986-01-01

30

CD4 nadir is a predictor of HIV neurocognitive impairment in the era of combination antiretroviral therapy  

PubMed Central

Objective Despite immune recovery in individuals on combination antiretroviral therapy (CART), the frequency of HIV-associated neurocognitive disorders (HANDs) remains high. Immune recovery is typically achieved after initiation of ART from the nadir, or the lowest historical CD4. The present study evaluated the probability of neuropsychological impairment (NPI) and HAND as a function of CD4 nadir in an HIV-positive cohort. Methods One thousand five hundred and twenty-five HIV-positive participants enrolled in CNS HIV Antiretroviral Therapy Effects Research, a multisite, observational study that completed comprehensive neurobehavioral and neuromedical evaluations, including a neurocognitive test battery covering seven cognitive domains. Among impaired individuals, HAND was diagnosed if NPI could not be attributed to comorbidities. CD4 nadir was obtained by self-report or observation. Potential modifiers of the relationship between CD4 nadir and HAND, including demographic and HIV disease characteristics, were assessed in univariate and multivariate analyses. Results The median CD4 nadir (cells/?l) was 172, and 52% had NPI. Among impaired participants, 603 (75%) had HAND. Higher CD4 nadirs were associated with lower odds of NPI such that for every 5-unit increase in square-root CD4 nadir, the odds of NPI were reduced by 10%. In 589 virally suppressed participants on ART, higher CD4 nadir was associated with lower odds of NPI after adjusting for demographic and clinical factors. Conclusion As the risk of NPI was lowest in patients whose CD4 cell count was never allowed to fall to low levels before CART initiation, our findings suggest that initiation of CART as early as possible might reduce the risk of developing HAND, the most common source of NPI among HIV-infected individuals.

Ellis, Ronald J.; Badiee, Jayraan; Vaida, Florin; Letendre, Scott; Heaton, Robert K.; Clifford, David; Collier, Ann C.; Gelman, Benjamin; McArthur, Justin; Morgello, Susan; McCutchan, J. Allen; Grant, Igor

2013-01-01

31

Clinical Results with the Trabectome for Treatment of Open-Angle Glaucoma  

Microsoft Academic Search

Objective: To describe clinical results from a pilot study of a novel glaucoma surgical device. Design: Prospective interventional case series. Participants: Thirty-seven adult Hispanic and Caucasian patients (17 male, 20 female) with uncontrolled open-angle glaucoma (OAG) in one or both eyes with or without previous surgery or laser treatment were recruited from a clinical practice in Tijuana, Mexico. Intervention: Surgery

Don S. Minckler; George Baerveldt; Marina Ramirez Alfaro; Brian A. Francis

32

Aerosol measurements in the IR: from limb to nadir?  

NASA Technical Reports Server (NTRS)

Vertical profiles of aerosol concentration have been derived from the ATMOS solar occultation dataset. The EOS instrument TES has motivated studies of the feasibility of quantifying aerosols in nadir and limb emission measurements.

Eldering, A.; Irion, F. W.; Mills, F. P.; Steele, H. M.; Gunson, M. R.

2001-01-01

33

Vegetation reflectance measurements as a function of solar zenith angle  

NASA Technical Reports Server (NTRS)

An understanding of the behavior of vegetation canopy reflectance as a function of solar zenith angle is important to several remote sensing applications. Spectral hemispherical-conical reflectances of a nadir looking sensor were taken throughout the day of a lodgepole pine and two grass canopies. Mathematical simulations of both a spectral hemispherical-conical reflectance factor and a spectral bi-hemispherical reflectance were performed for two theoretical canopies of contrasting geometric structure. These results and results from literature studies showed a great amount of variability of vegetation canopy reflectances as a function of solar zenith angle. Explanations for this variability are discussed and recommendations for future measurements are proposed.

Kimes, D. S.; Smith, J. A.; Ranson, K. J.

1980-01-01

34

NO2 from SCIAMACHY limb and nadir measurements - validation of the operational data products  

NASA Astrophysics Data System (ADS)

SCanning Imaging Absorption spectroMeter for Atmospheric CHartograpY (SCIAMACHY), aboard Envisat, 2002-2012, observed the transmitted, scattered and reflected solar radiation from the earth's atmosphere in limb, nadir and solar/lunar occultation geometries covering UV-Visible to NIR (240-2830 nm) spectral range with a moderate spectral resolution of 0.2-1.5nm. Monitoring the stability and verifying the quality of its decadal scale products is a prerequisite to their usage for long term analysis and interpretations, as well as stratospheric ozone studies and assessments. With this perspective, the ESA project SCILOV-10 (SCIAMACHY long term validation 2010) aims at the lifetime validations and documentation of the quality of various operational data products retrieved from SCIAMACHY in limb and nadir geometries. The limb observations provide vertically resolved global coverage and the nadir measurements give vertical column amounts on the same coverage scale. NO2 plays an important role in the stratospheric ozone chemistry by controlling the ozone abundances through catalytic destruction or by mitigating ozone depletion through reservoir formation. In the troposphere its concentration determines the ozone amount. Here we present the validation results of the operational limb stratospheric NO2 profiles and the nadir NO2 total column products. The limb dataset is compared with the corresponding scientific SCIAMACHY retrievals at the Institute of Environmental Physics (IUP) Bremen and with correlative measurements form other satellites as ACE-FTS, HALOE, SAGE II and OSIRIS. The nadir product is validated with the corresponding IUP measurements and with GOME NO2 data product.

Azam, Faiza; Weigel, Katja; Weber, Mark; Rozanov, Alexei; Bovensmann, Heinrich; Burrows, John P.

2014-05-01

35

Postlaunch performance of the Suomi National Polar-orbiting Partnership Ozone Mapping and Profiler Suite (OMPS) nadir sensors  

NASA Astrophysics Data System (ADS)

prelaunch specifications for nadir sensors of the Ozone Mapping and Profiler Suite (OMPS) were designed to ensure that measurements from them could be used to retrieve total column ozone and nadir ozone profile information both for operational use and for use in long-term ozone data records. In this paper, we will show results from our extensive analysis of the performance of the nadir mapper (NM) and nadir profiler (NP) sensors during the first year and a half of OMPS nadir operations. In most cases, we determined that both sensors meet or exceed their prelaunch specifications. Normalized radiance (radiance divided by irradiance) measurements have been determined to be well within their 2% specification for both sensors. In the case of stray light, the NM sensor is within its 2% specification for all but the shortest wavelengths, while the NP sensor is within its 2% specification for all but the longest wavelengths. Artifacts that negatively impacted the sensor calibration due to diffuser features were reduced to less than 1% through changes made in the solar calibration sequence. Preliminary analysis of the disagreement between measurements made by the NM and NP sensors in the region where their wavelengths overlap indicates that it is due to shifts in the shared dichroic filter after launch and that it can be corrected. In general, our analysis indicates that both the NM and NP sensors are performing well, that they are stable, and that any deviations from nominal performance can be well characterized and corrected.

Seftor, C. J.; Jaross, G.; Kowitt, M.; Haken, M.; Li, J.; Flynn, L. E.

2014-04-01

36

Comparison of OClO nadir measurements from SCIAMACHY and GOME  

NASA Astrophysics Data System (ADS)

The scanning imaging absorption spectrometer for atmospheric chartography was launched successfully onboard ENVISAT on March 1, 2002. It observes the solar radiation transmitted and backscattered from the atmosphere and reflected from the ground in nadir, limb and occultation viewing modes. Chlorine dioxide (OClO), an important indicator for stratospheric chlorine activation, can be measured in the UV spectral range by differential optical absorption spectroscopy (DOAS). First results of the DOAS retrieval of OClO slant column densities from the SCIAMACHY nadir measurements are presented and compared to measurements of the global ozone monitoring experiment (GOME), which has successfully measured OClO since 1995. While SCIAMACHY operates in the same orbit, it measures ?30 min earlier than GOME and has an increased spatial resolution (30 × 60 km2 compared to 40 × 320 km2 for GOME).

Kühl, Sven; Wilms-Grabe, Walburga; Frankenberg, Christian; Grzegorski, Michael; Platt, Ulrich; Wagner, Thomas

37

NADIR (Network Anomaly Detection and Intrusion Reporter): A prototype network intrusion detection system  

SciTech Connect

The Network Anomaly Detection and Intrusion Reporter (NADIR) is an expert system which is intended to provide real-time security auditing for intrusion and misuse detection at Los Alamos National Laboratory's Integrated Computing Network (ICN). It is based on three basic assumptions: that statistical analysis of computer system and user activities may be used to characterize normal system and user behavior, and that given the resulting statistical profiles, behavior which deviates beyond certain bounds can be detected, that expert system techniques can be applied to security auditing and intrusion detection, and that successful intrusion detection may take place while monitoring a limited set of network activities such as user authentication and access control, file movement and storage, and job scheduling. NADIR has been developed to employ these basic concepts while monitoring the audited activities of more than 8000 ICN users.

Jackson, K.A.; DuBois, D.H.; Stallings, C.A.

1990-01-01

38

Nadir looking airborne radar and possible applications to forestry  

Microsoft Academic Search

It is shown that investigators can use an airborne radar with high range resolution to measure the height and planting density of trees in forests. Based on C-band, nadir looking airborne radar data from a site in Southwest France, a single-scattering model is developed and verified to aid in the interpretation of such data.

R. Bernard; M. E. Frezal; D. Vidal-Madjar; D. Guyon; J. Riom

1987-01-01

39

Nadir observations of sprites from the International Space Station  

Microsoft Academic Search

The experiment LSO (Lightning and Sprite Observations) is dedicated to the optical study, from the International Space Station, of sprites occurring in the upper atmosphere above thunderstorms. The objectives were to study these phenomena and to validate a new measurement concept for future measurements of sprites from space at the nadir. The first measurements were performed in the frame of

E. Blanc; T. Farges; R. Roche; D. Brebion; T. Hua; A. Labarthe; V. Melnikov

2004-01-01

40

Computer communications through telecommunications satellite systems - The NADIR project  

Microsoft Academic Search

Current developments in satellite digital communication in Europe are surveyed, and the status of the French NADIR project begun in 1980 is reported. The geographic coverage, transmission rates, propagation delays, broadcasting and multidestination channels, and error rates characteristic of present satellite systems are discussed, and the specific performance parameters of the Telecom-1 system, comprising three geosynchronous satellites (one operational and

J.-L. Grange

1983-01-01

41

Interpreting vegetation reflectance measurements as a function of solar zenith angle  

NASA Technical Reports Server (NTRS)

Spectral hemispherical-conical reflectances of a nadir looking sensor were taken throughout the day for a lodgepole pine and two grass canopies. Mathematical simulations of both spectral hemispherical-conical and bi-hemispherical reflectances were performed for two theoretical canopies of contrasting geometric structure. These results and comparisons with literature studies showed a great amount of variability of vegetation canopy reflectances as a function of solar zenith angle. Explanations for this variability are discussed and recommendations for further measurements are proposed.

Kimes, D. S.; Smith, J. A.; Ranson, K. J.

1979-01-01

42

Nadir Sounding of Carbon Gases using SCIAMACHY Near Infrared Channels  

NASA Astrophysics Data System (ADS)

The Beer InfraRed Retrieval Algorithm (BIRRA) and Column EstimatoR Vertical InfraRed Sounding Atmosphere (CERVISA) codes have been designed to retrieve vertical column den-sities (VCDs) of atmospheric gases in the near and thermal infrared (NIR,TIR) region of the electromagnetic spectrum by means of non-linear least squares fitting of radiances. As part of the operational SCIAMACHY level 1-2 processor, BIRRA is currently used for the specific retrieval of carbon monoxide (CO) VCDs exploiting the fitting window 4282-4301 cm-1 within the SCIAMACHY channel 8. Using appropriate fitting windows in channel 6, BIRRA also allows to gain information on greenhouse gases such as methane and carbon dioxide. Unfortunately, the increasing number of dead and bad pixels -specially in the NIR channels -reduces the available spectral information and consequently makes the VCDs retrieval more and more challenging. The proper choice of the pixel mask, fitting window, auxiliary fit parameters, as well as the filtering of the Level 2 data is crucial for obtaining a high quality atmospheric product. For validation of BIRRA the closely related CERVISA code is used to retrieve CO and CH4 from nadir infrared sounding data of AIRS, IASI, or TES. BIRRA and CERVISA share a large portion of modules, e.g., for line-by-line absorption and the nonlinear least squares solver; the essential difference is the part of the forward model devoted to radiative transfer through the atmosphere, i.e., Beer's law for the NIR versus Schwarzschild's equation for the TIR. CERVISA retrieval results are compared both to the operational products of the TIR sounder and to the SCIAMACHY-BIRRA product. In this work, we present recent results of carbon monoxide and methane retrievals.

Gimeno García, Sebastián; Schreier, Franz; Lichtenberg, Günter; Slijkhuis, Sander; Hess, Michael; Aberle, Bernd

43

Tropospheric ozone retrieval by using SCIAMACHY Limb-Nadir-Matching method  

NASA Astrophysics Data System (ADS)

Tropospheric ozone is photochemically produced during pollution events and transported from the stratosphere towards the troposphere. It is the third most important green house gases and the main component of summer smog. Global covered satellite measurements are well suitable to investigate sources, sinks, and transport mechanisms of tropospheric ozone in a global view, and to study a characteristic behaviour of the tropospheric ozone in regions. However, the usage of satellite data is associated to a large uncertainty as 90% ozone is located in the stratosphere and only the remaining part of 10% can be observed in the troposphere. The limb-nadir matching (LNM) technique is one of the methods suitable to retrieve tropospheric ozone distributions from space borne observations of the scattered solar light in the UV-visible spectral range. In this study we apply the LNM approach to alternating limb and nadir measurements performed by the SCIAMACHY instrument. A precise tropopause height is used to subtract the stratospheric ozone from the total ozone amount for each matching point. The focus of this work is to reduce the uncertainty of the resulting tropospheric ozone distributions by analysing possible error sources, refining both limb and nadir retrievals and the matching technique.

Jia, Jia; Ladstätter-Weissenmayer, Annette; Ebojie, Felix; Rozanov, Alexei; Burrows, John

2014-05-01

44

Structured water in polyelectrolyte dendrimers: Understanding small angle neutron scattering results through atomistic simulation  

NASA Astrophysics Data System (ADS)

Based on atomistic molecular dynamics (MD) simulations, the small angle neutron scattering (SANS) intensity behavior of a single generation-4 polyelectrolyte polyamidoamine starburst dendrimer is investigated at different levels of molecular protonation. The SANS form factor, P(Q), and Debye autocorrelation function, ?(r), are calculated from the equilibrium MD trajectory based on a mathematical approach proposed in this work. The consistency found in comparison against previously published experimental findings (W.-R. Chen, L. Porcar, Y. Liu, P. D. Butler, and L. J. Magid, Macromolecules 40, 5887 (2007)) leads to a link between the neutron scattering experiment and MD computation, and fresh perspectives. The simulations enable scattering calculations of not only the hydrocarbons but also the contribution from the scattering length density fluctuations caused by structured, confined water within the dendrimer. Based on our computational results, we explore the validity of using radius of gyration RG for microstructure characterization of a polyelectrolyte dendrimer from the scattering perspective.

Wu, Bin; Kerkeni, Boutheïna; Egami, Takeshi; Do, Changwoo; Liu, Yun; Wang, Yongmei; Porcar, Lionel; Hong, Kunlun; Smith, Sean C.; Liu, Emily L.; Smith, Gregory S.; Chen, Wei-Ren

2012-04-01

45

Method for evaluating bow tie filter angle-dependent attenuation in CT: Theory and simulation results  

SciTech Connect

Purpose: Dosimetry in computed tomography (CT) is increasingly based on Monte Carlo studies that define the dose in the patient (in mGy) as a function of air kerma (free in air) at isocenter (mGy). The accuracy of Monte Carlo studies depends in part on the accuracy of the characterization of the bow tie filter for a given CT scanner model. A simple method for characterizing the bow tie filter attenuation profile in CT scanners would therefore be very useful. The theory behind such a method is proposed. Methods: A measurement protocol is discussed mathematically and demonstrated using computer simulation. The proposed method requires the placement of a radiation monitor at the periphery of the CT field, and the time domain signal (kerma rate versus time) is measured with good temporal resolution ({approx}200 Hz or better) and with all other objects (e.g., patient couch) retracted from the field of view. Knowledge of the source to isocenter distance (or alternately, the isocenter to probe distance) is required. The stationary detector records the kerma rate versus time signal as the gantry rotates through several revolutions. From this temporal data, signal processing techniques are used to extract in-phase peaks, as well as out-of-phase kerma rate levels. From these data, the distance from isocenter to the probe can be determined (or, alternatively, the source to isocenter distance), and the angle-dependent bow tie filter attenuation can be computed. By measuring the angle-dependent bow tie filter attenuation at several kVp settings, the bow tie composition versus fan angle can be computed using basis decomposition techniques. Results: The simulations illustrated that with 2% added noise in the kerma rate versus time signal, the attenuation properties of a hypothetical two component (aluminum and polymethyl methacrylate) bow tie filter could be determined (r{sup 2}>0.99). Although the computed basis material thicknesses were not exactly equal to the actual thicknesses, their combined attenuation factors matched that of the actual filter across kVp's to within an average of 0.057%. Conclusions: It is concluded that the proposed method may provide a simple noninvasive approach to characterizing the performance of bow tie filters in CT systems; however, experimental validation is necessary.

Boone, John M. [Department of Radiology and Department of Biomedical Engineering, UC Davis Medical Center, University of California, Davis, 4860 Y Street, Suite 3100, Sacramento, California 95817 (United States)

2010-01-15

46

Inner Jet Spread Angles of Coaxial Jets from Subcritical to Supercritical Conditions with Preliminary Numerical Results.  

National Technical Information Service (NTIS)

A study is performed to analyze the behavior of the inner jet spread angles in a coaxial jet flow configuration similar to those used in liquid rocket engines. These angles are measured from back-lit images. Data is presented for sub-, near-, and supercri...

D. Talley H. Lyu I. A. Leyva J. I. Rodriguez J. J. Graham

2008-01-01

47

Validation of Jason1 Nadir Ionosphere TEC Using GEONET  

Microsoft Academic Search

The Jason-1 dual-frequency nadir ionosphere Total Electron Content (TEC) for 10-day cycles 1–67 is validated using absolute TEC measured by Japan's GPS Earth Observation Network (GEONET), or the GEONET Regional Ionosphere Map (RIM). The bias estimates (Jason–RIM) are small and statistically insignificant: 1.62 ± 9 TECu (TEC unit or 10 electrons\\/m, 1 TECu = 2.2 mm delay at Ku-band) and

JINSONG PING; KOJI MATSUMOTO; KOSUKE HEKI; AKINORI SAITO; PHILIP CALLAHAN; LARAMIE POTTS; C. K. SHUM

2004-01-01

48

Short-Term Results of Canaloplasty Surgery for Primary Open-Angle Glaucoma in Japanese Patients  

PubMed Central

Purpose To report surgical results of canaloplasty surgery for primary open-angle glaucoma (POAG) in Japanese patients. Methods Eleven eyes of 9 POAG patients underwent canalopasty surgery at Toyama University Hospital. Three eyes of 3 patients underwent canaloplasty alone and 8 eyes of 6 patients underwent canaloplasty combined with cataract surgery. Canaloplasty was performed with a 10-0 polypropylene tensioning suture and an iTrack™ 250A microcatheter. All patients were followed up for 12 months. Changes in intraocular pressure (IOP) and postoperative complications were examined. Results Mean preoperative IOP was 23.4 ± 5.5 mm Hg. Mean number of antiglaucoma drops was 2.8 ± 0.6 before canaloplasty and decreased to 1.2 ± 0.8 at 12 months after canaloplasty (p < 0.01). Mean IOP decreased postoperatively, being 13.7 ± 2.8 mm Hg at 1 month, 12.8 ± 3.5 mm Hg at 3 months, 14.0 ± 4.4 mm Hg at 6 months, and 15.0 ± 4.1 mm Hg at 12 months. The most frequent postoperative complication was mild hyphema (45.5%), which disappeared within 14 days after surgery. Conclusions Canaloplasty may be an alternative surgery for POAG patients to reduce IOP to a value of approximately 15 mm Hg.

Fujita, Kazuya; Kitagawa, Kiyotaka; Ueta, Yoshiki; Nakamura, Tomoko; Miyakoshi, Akio; Hayashi, Atsushi

2011-01-01

49

Thermal infrared nadir observations of 24 atmospheric gases  

NASA Astrophysics Data System (ADS)

Thermal infrared nadir sounders are ideal for observing total columns or vertical profiles of atmospheric gases such as water, carbon dioxide and ozone. High resolution sounders with a spectral resolution below 5 cm-1 can distinguish fine spectral features of trace gases. Forty years after the launch of the first hyperspectral sounder IRIS, we have now several state of the art instruments in orbit, with improved instrumental specifications. In this letter we give an overview of the trace gases which have been observed by infrared nadir sounders, focusing on new observations of the Infrared Atmospheric Sounding Interferometer (IASI). We present typical observations of 14 rare reactive trace gas species. Several species are reported here for the first time in nadir view, including nitrous acid, furan, acetylene, propylene, acetic acid, formaldehyde and hydrogen cyanide, observations which were made in a pyrocumulus cloud from the Australian bush fires of February 2009. Being able to observe this large number of reactive trace gases will likely improve our knowledge of source emissions and their impact on the environment and climate.

Clarisse, Lieven; R'Honi, Yasmina; Coheur, Pierre-François; Hurtmans, Daniel; Clerbaux, Cathy

2011-05-01

50

Seismogenic Processes In The Nankai Trough: Results Form Wide-angle Seismic Surveys  

NASA Astrophysics Data System (ADS)

Active seismic studies to reveal the seismogenic zone structure have been widely car- ried out in the Nankai trough since the last five years. A subducted seamount colliding to the Japanese island arc crust was successfully imaged off the cape Muroto by an extensive active seismic survey. This subducted seamount is proposed as a barrier preventing a lateral propagation of the co-seismic rupture during the 1946 Nankaido Earthquake. In terms of the rupture process of the 1944 Nankaido Earthquake, both seismic and tsunami data (Kikuchi and Yamanaka, 2001; Tanioka and Satake, 1999) show the co-seismic ruptures were concentrated at the east of the Kii peninsula and did not extend to the Tokai district. Historic earthquake data also show that a recur- rence interval of the mega-thrust earthquakes off the Tokai district is not as regular as at other areas in the Nankai Trough. A key question is, therefore, if there is signifi- cant structural factor to prevent the rupture in this area. Even though it is proposed the Paleo-Zenisu ridge might be subducted in the eastern Nankai trough, no clear seismic image has been obtained. In July to August of 2001, an active seismic study using a super densely deployed OBS array was performed, as a part of an onshore-offshore wide-angle seismic survey, off the Tokai district. Results of first arrival tomography of the wide-angle seismic data show following structures: i) root of the Zenisu ridge ex- tends down to 15-20 km depth consisting of thicker lower crustal body (Vp = 6.6 - 7.4 km/s), ii) slightly thickening of subducted oceanic crust is recognized at immediately landward the Nankai trough suggesting the possible Paleo-Zenisu ridge. But, crustal volume of the Paleo-Zenisu might be significantly smaller than the present day Zenisu ridge, iii) abrupt thickening of middle (Vp =6.0 - 6.4 km/s) and lower (Vp=6.6-7.4 km/s) crust toward the Izu island arc is observed at the southern end of the profile. The structure representing the subducted Paleo-Zenisu Ridge is located immediately out side of the 1944 Tonankai Eearthquake, where recurrence interval of the mega- thrust earthquakes is longer than other area in the Nankai Trough.

Kodaira, S.; Nakanishi, A.; Park, J.-O.; Kaneda, Y.

51

[Study of hyperspectral polarized reflectance of vegetation canopy at nadir viewing direction].  

PubMed

In the present study, corn canopy is the objective. Firstly the polarization of corn canopy was analyzed based on polarization reflection mechanism; then, the polarization of canopy was measured in different growth period at nadir before heading. The result proved the theoretical derivation that the light reflected from corn canopy is polarized, and found that in the total reflection the polarization light accounts for up to 10%. This shows that polarization measurement provides auxiliary information for remote sensing, but also illustrates that the use of the polarization information retrieval of atmospheric parameters should be considered when the surface polarization affects on it. PMID:23841422

L?, Yun-Feng

2013-04-01

52

NADIR: Monitoring, Error Handling, and Logging with Tango  

NASA Astrophysics Data System (ADS)

The ingest and transport of a large amount of astronomical data, in geographically distributed archives, imply some challenging issues, like remote control and configuration, monitoring and logging anomalous conditions, fault tolerance and error handling. Based on this considerations and on our experience in data management, we started development of a New Archiving Distributed InfrastructuRe (NADIR), using Tango (Team 2013; S. Gara 2012), a well known distributed control system (DCSs) within scientific environments, taking advantage of its key features, like reliability, scalability, logging and alarm system, consolidated pattern and template, to solve this complexity. In this paper we discuss about design choices and technical aspects around this project.

De Marco, M.; Knapic, C.; Smareglia, R.

2014-05-01

53

The swept angle retarding mass spectrometer: Initial results from the Michigan auroral probe sounding rocket  

NASA Technical Reports Server (NTRS)

Data from a sounding rocket flight of the swept angle retarding ion mass spectrometer (SARIMS) are presented to demonstrate the capability of the instrument to make measurements of thermal ions which are differential in angle, energy, and mass. The SARIMS was flown on the Michigan auroral probe over regions characterized first by discrete auroral arcs and later by diffuse precipitation. The instrument measured the temperature, densities, and flow velocities of the ions NO(+) and O(+). Measured NO(+) densities ranged from 10 to the 5th power up to 3 x 10 to the 5th power ions/cu cm, while the measured O(+) densities were a factor of 5-10 less. Ion temperatures ranged from 0.15 up to 0.33 eV. Eastward ion flows approximately 0.5 km/sec were measured near the arcs, and the observed flow magnitude decreased markedly inside the arcs.

Reasoner, D. L.; Chappell, C. R.; Stone, N. H.; Sharp, W. E.; Hoffman, J. H.

1980-01-01

54

Volar fixed-angle plate osteosynthesis of unstable distal radius fractures: 12 months results  

Microsoft Academic Search

Background  With an incidence of about 2–4 per 1,000 residents per year, the distal radial fracture is the most common fracture in the\\u000a human skeleton. The introduction of fixed-angle plate systems for extension fractures at the radius was evaluated in a prospective\\u000a study performed at our hospital after selection and acquisition of a new system. The focus of our interest was

Markus Figl; Patrick Weninger; Michael Liska; Marcus Hofbauer; Martin Leixnering

2009-01-01

55

First aircraft experiment results with the wide-angle airborne laser ranging system  

Microsoft Academic Search

The first aircraft experiment with the Wide-Angle Airborne Laser Ranging System has been conducted in May 1998 over an air base in France equipped with a network of 64 cub-corner retroreflectors. The ranging system was operated from the Avion de Recherche Atmospherique et de Teledetection of CNES\\/IGN\\/INSU. Data have been collected during two 4-hour flights. The paper describes the data

Olivier Bock; Christian Thom; Michel Kasser

1999-01-01

56

Results of the first aircraft experiment with the wide-angle airborne laser ranging system  

Microsoft Academic Search

The first aircraft experiment with the wide-angle airborne laser ranging system has been conducted in May 1998 over a small network of 1 km2, equipped with 64 cube-corner retroreflectors. The ranging system was operated from a research aircraft (ARAT, Fokker 27) at an altitude of 1 km. Data have been collected during two 4-hour flights. The paper describes the data

O. Bock

2000-01-01

57

Magnetic merging line and reconnection voltage versus IMF clock angle: Results from global MHD simulations  

NASA Astrophysics Data System (ADS)

This paper proposes diagnosis methods to trace the magnetic merging line and to calculate the electric potential along it for Earth's magnetospheric magnetic fields obtained by global magnetohydrodynamic (MHD) simulations of the solar wind-magnetosphere-ionosphere (SMI) system. The points with minimum magnetic field strength along last closed magnetic field lines and properly selected closed field lines are combined to trace the whole merging line, and the radial ray integration of convectional electric field is used to calculate the electric potential on the merging line. The diagnosis methods are then applied to magnetospheric magnetic fields associated with different interplanetary magnetic field (IMF) clock angles, and a preliminary analysis is presented on the clock angle response of the geometry of the merging line and the associated reconnection voltage. The merging line is found to be similar in geometry to that of the compound field superposed by the Earth's dipole field and the IMF, whereas the reconnection voltage is approximately fitted by sin3/2($\\theta$ IMF/2) for its response to the IMF clock angle $\\theta$ IMF. The ionospheric transpolar potential and the voltage along the polar cap boundary show different dependence from that of the reconnection voltage, so it is not justified to take them as substitutes for the reconnection voltage. The length of the sunward merging line between the two peaks of reconnection potential shows a nonmonotonic variation in response to $\\theta$ IMF, peaked at $\\theta$ IMF = 90°, so it is also not justified to take electric fields along the merging line, however defined they may be, to characterize the total reconnection rate and the coupling strength between the solar wind and the magnetosphere. The reconnection nearby magnetic nulls closest to the subsolar point is found to be negligible, which gives support to the component reconnection hypothesis for dayside reconnection of quasi-steady states of the SMI system.

Hu, Y. Q.; Peng, Z.; Wang, C.; Kan, J. R.

2009-08-01

58

Crown depth as a result of evolutionary games: decreasing solar angle should lead to shallower, not deeper crowns.  

PubMed

There is a general notion in the literature that, with increasing latitude, trees have deeper crowns as a result of a lower solar elevation angle. However, these predictions are based on models that did not include the effects of competition for light between individuals. Here, I argue that there should be selection for trees to increase the height of the crown base, as this decreases shading by neighbouring trees, leading to an evolutionarily stable strategy (ESS). Because the level of between-tree shading increases with decreasing solar angle, the predicted ESS will shift to higher crown base height. This argument is supported by a simulation model to check for the effects of crown shape and the change of light intensity that occurs with changing solar angle on model outcomes. So, the lower solar angle at higher latitudes would tend to select for shallower, and not deeper, crowns. This casts doubt on the common belief that a decreasing solar angle increases crown depth. More importantly, it shows that different assumptions about what should be optimized can lead to different predictions, not just for absolute trait values, but for the direction of selection itself. PMID:24548219

Vermeulen, Peter Johannes

2014-06-01

59

Improvements to the retrieval of tropospheric NO2 from satellite - stratospheric correction using SCIAMACHY limb/nadir matching and comparison to Oslo CTM2 simulations  

NASA Astrophysics Data System (ADS)

Satellite measurements of atmospheric trace gases have proved to be an invaluable tool for monitoring the Earth system. When these measurements are to be used for assessing tropospheric emissions and pollution, as for example in the case of nadir measurements of nitrogen dioxide (NO2), it is necessary to separate the stratospheric from the tropospheric signal. The SCIAMACHY instrument offers the unique opportunity to combine its measurements in limb- and nadir-viewing geometries into a tropospheric data product, using the limb measurements of the stratospheric NO2 abundances to correct the nadir measurements' total columns. In this manuscript, we present a novel approach to limb/nadir matching, calculating one stratospheric NO2 value from limb measurements for every single nadir measurement, abandoning global coverage for the sake of spatial accuracy. For comparison, modelled stratospheric NO2 columns from the Oslo CTM2 are also evaluated for stratospheric correction. Our study shows that stratospheric NO2 columns from SCIAMACHY limb measurements very well reflect stratospheric conditions. The zonal variability of the stratospheric NO2 field is captured by our matching algorithm, and the quality of the resulting tropospheric NO2 columns improves considerably. Both stratospheric datasets need to be adjusted to the level of the nadir measurements, because a time- and latitude-dependent bias to the measured nadir columns can be observed over clean regions. After this offset is removed, the two datasets agree remarkably well, and both stratospheric correction methods provide a significant improvement to the retrieval of tropospheric NO2 columns from the SCIAMACHY instrument.

Hilboll, A.; Richter, A.; Rozanov, A.; Hodnebrog, Ø.; Heckel, A.; Solberg, S.; Stordal, F.; Burrows, J. P.

2013-03-01

60

Long-term stability of Angle Class II, Division 1 malocclusions with successful occlusal results at end of active treatment  

Microsoft Academic Search

The purpose of this study was to examine long-term stability of Angle Class II, Division 1 malocclusions with successful occlusal results at the end of active appliance therapy, search for predictors of relapse, and look for characteristics associated with successful treatment. Records taken before and after treatment and a mean of 14.0 years postretention of adolescent patients treated for a

Brett C. Fidler; Jon Årtun; Donald R. Joondeph; Robert M. Little

1995-01-01

61

Retrieval of carbon monoxide vertical column densities from SCIAMACHY infrared nadir observations  

NASA Astrophysics Data System (ADS)

Nadir observations in the shortwave infrared channels of SCIAMACHY onboard the ENVISAT satellite can be used to derive information on CO, CH4, N2O, CO2, and H2O. Several scientific data analysis tools have been developed for retrieval of vertical column densities, and a significant upgrade of the operational level 2 data processor has been prototyped recently at DLR-RSTI to gain greater flexibility in the forward modelling and a more efficient and robust least squares inversion. BIRRA (Beer InfraRed Retrieval Algorithm) is a least squares fit of the measured radiance with respect to molecular column densities and auxiliary parameters, nb. surface albedo, baseline and slit function width. In this poster unique/special/distinguished features of the code (e.g., separable least squares exploiting the special structure of the model function) are shown along with results of carbon monoxide retrievals from SCIAMACHY near infrared nadir observations. The sensitivity of the results with respect to various forward model and inversion parameter settings will be discussed. In particular intercomparisons with AIRS (Atmospheric Infrared Sensor onboard NASA-EOS-Aqua) will be presented.

Schreier, Franz; Gimeno--Garcia, Sebastian; Lichtenberg, Günter

62

The impact of ozone field horizontal inhomogeneities on nadir-viewing orbital backscatter UV measurements  

NASA Technical Reports Server (NTRS)

Radiative transfer calculations for nadir-viewing satellites normally assume the atmosphere to be horizontally homogeneous. Yet it has been shown recently that horizontal gradients can lead to significant errors in satellite infrared and microwave soundings. We extend the methodology to backscatter ultra-violet observations of ozone, and present a first estimate of the effect s magnitude. The Solar Backscatter Ultra-Violet/2 (SBUV/2) instrument, a pure nadir sounder, serves as our test bed. Our results indicate that in a vast majority of cases the abovementioned errors can be neglected. However, occurrence of higher errors, particularly at wavelengths longer than 300 nm, coincides with some of the most interesting atmospheric phenomena like tropopause folds and the South polar ozone hole. This leads to a seasonal variation of the magnitude of the effect. Due to the mostly zonal geometry of the ozone distribution, there is also the possibility that biases may be introduced, which is particularly critical if the data are to be assimilated or used to determine trends. The results presented are tested for robustness using different model atmospheres. The influence of horizontal inhomogeneities will be even more pronounced for cross-track sounders and limb viewers, and easier to detect once higher resolution atmospheric models are available. This will be investigated in future studies.

Mueller, Martin D.; Poli, Paul; Joiner, Joanna

2005-01-01

63

NPP VIIRS and Aqua MODIS RSB Comparison Using Observations from Simultaneous Nadir Overpasses (SNO)  

NASA Technical Reports Server (NTRS)

Suomi NPP (National Polar-orbiting Partnership) satellite (http://npp.gsfc.nasa.gov/viirs.html) began to daily collect global data following its successful launch on October 28, 2011. The Visible Infrared Imaging Radiometer Suite (VIIRS) is a key NPP sensor. Similar to the design of the OLS, SeaWiFS and MODIS instruments, VIIRS has on-board calibration components including a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) for the reflective solar bands (RSB), a V-groove blackbody for the thermal emissive bands (TEB), and a space view (SV) port for background subtraction. Immediately after the VIIRS nadir door s opening on November 21, 2011, anomalously large degradation in the SD response was identified in the near-IR wavelength region, which was unexpected as decreases in the SD reflectance usually occur gradually in the blue (0.4 m) wavelength region based on past experience. In this study, we use a well-calibrated Aqua MODIS as reference to track and evaluate VIIRS RSB stability and performance. Reflectances observed by both sensors from simultaneous nadir overpasses (SNO) are used to determine VIIRS to MODIS reflectance ratios for their spectral matching bands. Results of this study provide an immediate post-launch assessment, independent validation of the anomalous degradation observed in SD measurements at near-IR wavelengths and initial analysis of calibration stability and consistency.

Xiong, X.; Wu, A.

2012-01-01

64

NPP VIIRS and Aqua MODIS RSB comparison using observations from simultaneous nadir overpasses (SNO)  

NASA Astrophysics Data System (ADS)

Suomi NPP (National Polar-orbiting Partnership) satellite (http://npp.gsfc.nasa.gov/viirs.html) began to daily collect global data following its successful launch on October 28, 2011. The Visible Infrared Imaging Radiometer Suite (VIIRS) is a key NPP sensor. Similar to the design of the OLS, SeaWiFS and MODIS instruments, VIIRS has on-board calibration components including a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) for the reflective solar bands (RSB), a V-groove blackbody for the thermal emissive bands (TEB), and a space view (SV) port for background subtraction. Immediately after the VIIRS nadir door's opening on November 21, 2011, anomalously large degradation in the SD response was identified in the near-IR wavelength region, which was unexpected as decreases in the SD reflectance usually occur gradually in the blue (~0.4 ?m) wavelength region based on past experience. In this study, we use a well-calibrated Aqua MODIS as reference to track and evaluate VIIRS RSB stability and performance. Reflectances observed by both sensors from simultaneous nadir overpasses (SNO) are used to determine VIIRS to MODIS reflectance ratios for their spectral matching bands. Results of this study provide an immediate post-launch assessment, independent validation of the anomalous degradation observed in SD measurements at near-IR wavelengths and initial analysis of calibration stability and consistency.

Wu, Aisheng; Xiong, Xiaoxiong

2012-09-01

65

Preliminary Validation of SCIAMACHY Nadir OClO SCDs  

NASA Astrophysics Data System (ADS)

Measurements of OClO total columns can serve as an indicator of stratospheric chlorine activation. It has been shown in several studies that OClO observations from GOME are well suited to characterise the spatial and temporal evolution of the chlorine activation in both hemispheres. Here we present OClO observations from SCIAMACHY in nadir mode. Since to date no operational OClO products are available we investigated scientific products processed by the Universities of Heidelberg and Bremen. We compared the SCIAMACHY OClO SCDs to simultaneous observations from GOME and also to OClO observations made by the AMAYX-DOAS instrument on the DLR-Falcon. In both cases a good agreement was found. However, compared to GOME data the SCIAMACHY OClO SCDs still show a relatively large offset and scatter

Wagner, T.; Kühl, S.; Richter, A.; Bruns, M.; Burrows, J. P.; Heue, K.-P.; Kirchoff, B.; Wilms-Grabe, W.; Wang, P.; Platt, U.

2004-08-01

66

Computerized data reduction techniques for nadir viewing remote sensors  

NASA Technical Reports Server (NTRS)

Computer resources have been developed for the analysis and reduction of MAPS experimental data from the OSTA-1 payload. The MAPS Research Project is concerned with the measurement of the global distribution of mid-tropospheric carbon monoxide. The measurement technique for the MAPS instrument is based on non-dispersive gas filter radiometer operating in the nadir viewing mode. The MAPS experiment has two passive remote sensing instruments, the prototype instrument which is used to measure tropospheric air pollution from aircraft platforms and the third generation (OSTA) instrument which is used to measure carbon monoxide in the mid and upper troposphere from space platforms. Extensive effort was also expended in support of the MAPS/OSTA-3 shuttle flight. Specific capabilities and resources developed are discussed.

Tiwari, S. N.; Gormsen, Barbara B.

1985-01-01

67

Predictive value of CD4 cell count nadir on long-term mortality in HIV-positive patients in Uganda  

PubMed Central

Objective Although international guidelines recommend initiating antiretroviral therapy (ART) when a patient’s CD4 cell count is ?350 cells/?L, most patients in resource-limited settings present with much lower CD4 cell counts. The lowest level that their CD4 cell count reaches, the nadir, may have long-term consequences in terms of mortality. We examined this health state in a large cohort of HIV+ patients in Uganda. Design This was an observational study of HIV patients in Uganda aged 14 years or older, who were enrolled in 10 major clinics across Uganda. Methods We assessed the CD4 nadir of patients, using their CD4 cell count at initiation of ART, stratified into categories (,50, 50–99, 100–149, 150–249, 250+ cells/?L). We constructed Kaplan–Meier curves to assess the differences in survivorship for patients left-censored at 1 year and 2 years after treatment initiation. We used Cox proportional hazards regression to model the associations between CD4 nadir and mortality. We adjusted mortality for loss-to-follow-up. Results Of 22,315 patients, 20,129 patients had greater than 1 year of treatment follow-up. Among these patients, 327 (1.6%) died and 444 (2.2%) were lost to follow-up. After left-censoring at one year, relative to lowest CD4 strata, patients with higher CD4 counts had significantly lower rates of mortality (CD4 150–249, hazard ratio [HR] 0.60, 95% confidence interval [CI]: 0.45–0.82, P = 0.001; 250+, HR 0.66, 95% CI, 0.44–1.00, P = ?0.05). Male sex, older age, and duration of time on ART were independently associated with mortality. When left-censoring at 2 years, CD4 nadir was no longer statistically significantly associated with mortality. Conclusion After surviving for 1 year on ART, a CD4 nadir was strongly predictive of longer-term mortality among patients in Uganda. This should argue for efforts to increase engagement with patients to ensure a higher CD4 nadir at initiation of treatment.

Bray, Sarah; Gedeon, Jillian; Hadi, Ahsan; Kotb, Ahmed; Rahman, Tarun; Sarwar, Elaha; Savelyeva, Anna; Sevigny, Marika; Bakanda, Celestin; Birungi, Josephine; Chan, Keith; Yaya, Sanni; Deonandan, Raywat; Mills, Edward J

2012-01-01

68

Impact of baseline and nadir neutrophil index in non-small cell lung cancer and ovarian cancer patients: Assessment of chemotherapy for resolution of unfavourable neutrophilia  

PubMed Central

Background Chronic inflammation has been recognized to foster tumour development. Whether chemotherapy can be used to neutralize chronic inflammation is unclear. Methods We evaluated baseline and nadir neutrophils in 111 patients (pts.) with non-small cell lung cancer (NSCLC) and 118 pts. with ovarian cancer (OC) treated with chemotherapy administered with dose-individualization to achieve nadir neutropenia of 1.5. We used predefined baseline neutrophil cut-offs 4.5 × 109/L (NSCLC) and 3.9 × 109/L (OC). Results Absence of chemotherapy-induced nadir neutropenia (CTCAE grade 0, neutrophils???LLN) was seen in 23% of OC and 25% of NSCLC pts. Absence of nadir neutropenia was associated with decreased overall survival (OS) compared with presence (>grade 0) of neutropenia (9 vs. 14 months, P?=?0.004 for NSCLC and 23 vs. 56 months; P?=?0.01 for OC). Obtaining grade 3/4 neutropenia did not improve survival compared with grade 1/2 neutropenia. In multivariate analyses, baseline neutrophils ?4.5 × 109/L (HR: 2.0; 95% CI: 1.11-3.44;P = 0.02) and absence of nadir neutropenia (HR: 1.6; 95% CI: 1.02-2.65;P = 0.04) for NSCLC and absence of nadir neutropenia (HR: 1.7; 95% CI: 1.04;2.93;P = 0.04) for OC were independently associated with short OS. Three prognostic neutrophil index (NI) groups were defined. Favourable NI: low baseline neutrophils and presence of nadir neutropenia (>grade 0), Intermediate NI: elevated baseline neutrophils and presence of nadir neutropenia (>grade 0), and Poor NI: elevated baseline neutrophils and absence of nadir neutropenia (grade 0). For NSCLC patients, the median OS was 18.0, 13.4, and 8.8 months for favourable, intermediate and poor NI, respectively (fav vs. poor P?=?0.002; fav vs. intermed P?=?0.04; and intermed vs. poor P?=?0.03). For OC patients, median OS was 69, 52 and 23 months for favourable, intermediate and poor NI, respectively (fav vs. poor P?=?0.03; fav vs. intermed P?=?0.3; and intermed vs. poor P?=?0.02). Interestingly, survival rates in the intermediate NI groups indicated that individualised dose of chemotherapy to induce neutropenia may partly overcome the negative impact of elevated baseline neutrophils. Conclusions A neutrophil index comprising elevated baseline neutrophils and absence of neutropenia identified a high risk group of NSCLC and ovarian cancer patients with only modest effect of chemotherapy. New treatment options for this subset of patients are required.

2013-01-01

69

Prostate specific antigen nadir following external beam radiation therapy for clinically localized prostate Cancer: The relationship between nadir level and disease-free survival  

Microsoft Academic Search

PurposeWe determined whether the prostate specific antigen (PSA) nadir achieved following external beam radiation therapy alone predicts biochemical disease-free survival in a large cohort of men with clinically localized prostate cancer.

W. Robert Lee; Alexandria L. Hanlon; Gerald E. Hanks

1996-01-01

70

Preliminary results of polarimetry and photometry of Titan at large phase angles from Pioneer 11  

NASA Technical Reports Server (NTRS)

The imaging photopolarimeter (IPP) aboard the Pioneer 11 spacecraft measured the linear polarization of the integrated disk of Titan in red and blue light at a variety of phase angles from 15 to 97 deg. The large polarization (54%) measured in blue light at 90 deg phase constrains the size of the aerosols near the top of Titan's atmosphere to have radii smaller than about 0.09 microns if they have a refractive index of 2.0. The polarization at 90 deg phase in red light is smaller (41%) and implies that the optical thickness of the layer of small aerosols is about 0.6 above an effectively depolarizing surface. The shape of the polarization versus phase curve in blue light suggests increasing particle size with increasing depth into the atmosphere. The limb darkening of Titan was measured at 28 deg phase by using the imaging mode of the IPP. The limb darkening observed in both colors is reasonably consistent with that given by the scattering models derived from the polarization observations.

Tomasko, M. G.

1980-01-01

71

Cleaning results of new and fouled nanofiltration membrane characterized by contact angle, updated DSPM, flux and salts rejection  

NASA Astrophysics Data System (ADS)

In membrane process industries, membrane cleaning is one of the most important concerns from both economical and scientific points of view. Though cleaning is important to recover membrane performance, an inappropriate selection of cleaning agents may result into unsatisfactory cleaning or irreparable membrane. In this study the cleaning performance has been studied with measurements of membrane contact angle, Updated Donnan steric partitioning pore model (UDSPM) and salt rejection as well as flux measurement. Thin film nanofiltration (NF) membranes such as DK, HL and DL provided by GE Osmonics are used in this study. Tests were carried out with virgin DK, HL and DL as well as fouled DK membranes. Several cleaning agents were investigated; some of them were analytical grade such as HCl, NaOH and others such as SDS, mix agents were commercial grade agents that are already in use in commercial plants. Contact angle, DSPM and salt rejection as well as flux of virgin and fouled membranes before and after chemical cleaning were measured and compared. The contact angle measurements with and without chemical cleaning of different virgin and fouled membranes revealed very interesting results which may be used to characterise the membrane surface cleanliness. The contact angle results revealed that the cleaning agents are found to modify membrane surface properties (hydrophobicity/hydrophilicity) of the treated and untreated virgin and fouled membranes. The details of these results were also investigated and are reported in the paper. However, UDSPM method did not give any valuable information about pore size of the untreated and treated NF membranes. The salt rejection level of monovalent and divalent ions before and after cleaning by high and low pH cleaning agents is also investigated and is reported in the paper.

Al-Amoudi, Ahmed; Williams, Paul; Al-Hobaib, A. S.; Lovitt, Robert W.

2008-04-01

72

TES/Aura L2 Ammonia (NH3) Nadir (TL2NH3N)  

TES/Aura L2 Ammonia (NH3) Nadir (TL2NH3N) News:  TES News ... Level:  L2 Instrument:  TES/Aura L2 Ammonia Spatial Coverage:  5.3 x 8.5 km nadir ... Data: TES Order Tool Parameters:  Ammonia Order Data:  Reverb:   Order Data ...

2013-12-18

73

TES/Aura L2 Ammonia (NH3) Nadir (TL2NH3NS)  

TES/Aura L2 Ammonia (NH3) Nadir (TL2NH3NS) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Ammonia Spatial Coverage:  5.3 x 8.5 km nadir ... Data: TES Order Tool Parameters:  Ammonia Order Data:  Reverb:   Order Data ...

2013-12-18

74

Capturing tropospheric ozone time variability : a study using TES Nadir Retrievals  

NASA Technical Reports Server (NTRS)

We perform nadir retrievals of ozone using simulated radiances from ozone-sondes over Bermuda from April 14 to May 25, 1993. Using a novel two-step retrieval strategy, we characterize the sensitivity of TES nadir retrievals to time variations of ozone. 02000 Optical Society of America.

Bowman, Kevin; Steck, T.; Worden, H.; Worden, J.; Clough, S.; Rodgers, C.

2001-01-01

75

TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N)  

TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Carbon Dioxide Spatial Coverage:  5.2 x 8.5 km nadir ... Data: TES Order Tool Parameters:  Carbon Dioxide Order Data:  Reverb:   Order Data ...

2014-02-12

76

TES/Aura L2 Carbon Dioxide (CO2) Lite Nadir (TL2CO2LN)  

TES/Aura L2 Carbon Dioxide (CO2) Lite Nadir (TL2CO2LN) News:  TES ... Level:  L2 Instrument:  TES/Aura L2 Carbon Dioxide Spatial Coverage:  5.3 km nadir ... Data: TES Order Tool Parameters:  Carbon Dioxide Order Data:  Reverb:   Order Data ...

2013-11-06

77

TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2NS)  

TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2NS) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Carbon Dioxide Spatial Coverage:  5.3 x 8.5 km nadir ... Data: TES Order Tool Parameters:  Carbon Dioxide Order Data:  Reverb:   Order Data ...

2013-12-18

78

Optimal directional view angles for remote-sensing missions  

NASA Technical Reports Server (NTRS)

The present investigation is concerned with the directional, off-nadir viewing of terrestrial scenes using remote-sensing systems from aircraft and satellite platforms, taking into account advantages of such an approach over strictly nadir viewing systems. Directional reflectance data collected for bare soil and several different vegetation canopies in NOAA-7 AVHRR bands 1 and 2 were analyzed. Optimum view angles were recommended for two strategies. The first strategy views the utility of off-nadir measurements as extending spatial and temporal coverage of the target area. The second strategy views the utility of off-nadir measurements as providing additional information about the physical characteristics of the target. Conclusions regarding the two strategies are discussed.

Kimes, D. S.; Holben, B. N.; Tucker, C. J.; Newcomb, W. W.

1984-01-01

79

Failure-plane angle in Bentheim sandstone subjected to true triaxial stresses: experimental results and theoretical prediction  

NASA Astrophysics Data System (ADS)

We conducted true triaxial tests in the high-porosity (n = 24%), quartz-rich (95%), Bentheim sandstone. An important objective was to investigate the dependence of failure-plane angle ? (angle between the normal to the plane and ?1 direction) on the prevailing stress conditions. We employed two distinct loading paths, and seven ?3 magnitudes (between 0 and 150 MPa). In tests using the common loading path, ?2 and ?3 were fixed, while ?1 was raised monotonically to failure. In tests using the novel loading path (which facilitate comparison with theoretical predictions), ?3 was fixed, and the Lode angle, ? (= tan-1 [(?1 - 2?2 + ?3) / 30.5(?1 - ?3)]) was kept constant by raising ?1 and ?2 simultaneously at a set ratio b [= (?2 -?3)/(?1 -?3)] until failure occurred. Six stress ratios b (= 0, 1/6, 1/3, 1/2, 3/4, 1), i.e. six ? (= tan-1 [(1-2b) / 30.5]) values from +?/6 (axisymmetric compression) to -?/6 (axisymmetric extension) were used. In axisymmetric common loading path tests, failure-plane angle ? generally declined as the applied ?3 = ?2 increased from about 80° at ?3 = ?2 = 0 MPa to 0° at ?3 = ?2 = 150 MPa (forming compaction bands). In tests where ?3 ? ?2, the resulting failure-plane strike was consistently parallel to ?2 direction. For low ?3, ? typically rose by up to 12° as ?2 rose from ?2 = ?3 to ?2 = ?1. However, the rise in ? with ?2 tended to diminish at higher ?3. A limiting case occurred at ?3 = 150 MPa, where failure plane remained at 0° , regardless of the rise in ?2. In the novel loading path tests, failure-plane angle ? declined monotonically for any given Lode angle ?, from roughly 80° to 0° , as the mean stress at failure (?oct,f) rose from about 20 MPa to around 220 MPa; for a constant ?oct,f, ? typically increased from 10° (at ?oct,f = 20 MPa) to 30° (at ?oct,f = 220 MPa) as ? dropped from +?/6 (?2 = ?3) to -?/6 (?2 = ?1). We compared the measured ? with that predicted using equation 28 in Rudnicki (2013), an extension of the Rudnicki and Rice (1975) prediction to include the third stress invariant ?. (Space does not permit detailing the equation in this abstract.) The theory treats octahedral shear stress at failure (?oct,f) and the resulting ? as dependent on ?oct,f and ?. We used two series of the novel loading path tests: axisymmetric compression (? = +?/6) and pure shear (? = 0) to constrain that dependence. The failure conditions in the novel loading path tests were then simulated to compare the predicted failure-plane angles with the experimental results. The predictions were in general agreement with the experimental data, except when ? = -?/6 (?2 = ?1). In the common loading path tests, failure prediction replicated the general rise of the experimentally observed ? with ?2 for a given ?3,as well as the diminished rise at high ?3 magnitudes. The reasonable agreement between the predicted and the observed failure-plane angle demonstrated the applicability and the limitations of Rudnicki's (2013) theory.

Ma, Xiaodong; Rudnicki, John; Haimson, Bezalel

2014-05-01

80

First Results Obtained with Wide-Angle Cerenkov Light Telescope BEO p. Mussala  

Microsoft Academic Search

The first results from experiment using Cerenkov light of EAS, reflected from the snow surface of Ice Lake p. Mussala, Bulgaria are described. The construction of the telescope was started in autumn 2000.The first measurements with 1-meter diameter reflectors and FEU110 were carried out in winter 2000-2001. During 2002-2003 the detector was improved. The first results obtained in winter 2002-2003

E. Slavcheva Malamova; I. Angelov; K. Davidkov; J. Stamenov; I. Kirov

2003-01-01

81

Diode laser transscleral cyclophotocoagulation followed by phacotrabeculectomy on medically unresponsive acute primary angle closure eyes: the long-term result  

PubMed Central

Background To explore the intraocular pressure-lowering effect and complications of diode laser transscleral cyclophotocoagulation (DLTSC) followed by phacotrabeculectomy on medically unresponsive acute primary angle closure eyes. Methods Nine eyes of nine medically unresponsive acute primary angle closure patients were enrolled. All the patients underwent cyclophotocoagulation followed by phacotrabeculectomy to control the prolonged acute attack. Data were recorded prospectively and then analyzed retrospectively. The reduction in intraocular pressure, improvement of vision and the complications were evaluated. Results After DLTSC, the IOP of all the patients were reduced, but all were above 21 mmHg under topical anti-glaucoma medications. After phacotrabeculectomy, the IOP of all the patients was decreased. At the final visit, the vision of all the patients was improved and the IOP of all the patients was below 21 mmHg without anti-glaucoma medications. There were no complications during the DLTSC and phacotrabeculectomy. Uveitis was the common complications after the both procedures, which were resolved by medication treatment. Conclusion Diode laser transscleral cyclophotocoagulation followed by phacotrabeculectomy is an alternative procedure to control the intraocular pressure of medically unresponsive acute primary angle closure eyes with few complications.

2014-01-01

82

Tropospheric Ozone Near-Nadir-Viewing IR Spectral Sensitivity and Ozone Measurements from NAST-I  

NASA Technical Reports Server (NTRS)

Infrared ozone spectra from near nadir observations have provided atmospheric ozone information from the sensor to the Earth's surface. Simulations of the NPOESS Airborne Sounder Testbed-Interferometer (NAST-I) from the NASA ER-2 aircraft (approximately 20 km altitude) with a spectral resolution of 0.25/cm were used for sensitivity analysis. The spectral sensitivity of ozone retrievals to uncertainties in atmospheric temperature and water vapor is assessed in order to understand the relationship between the IR emissions and the atmospheric state. In addition, ozone spectral radiance sensitivity to its ozone layer densities and radiance weighting functions reveals the limit of the ozone profile retrieval accuracy from NAST-I measurements. Statistical retrievals of ozone with temperature and moisture retrievals from NAST-I spectra have been investigated and the preliminary results from NAST-I field campaigns are presented.

Zhou, Daniel K.; Smith, William L.; Larar, Allen M.

2001-01-01

83

Martian ice cloud distribution obtained from SPICAM nadir UV measurements  

NASA Astrophysics Data System (ADS)

The Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument on board Mars Express has successfully performed one Martian year of measurements. Nadir UV (200-310 nm) measurements allowed it to build maps of ice cloud optical depth distribution for all seasons. The development and decay of the aphelion cloud belt (ACB) and polar hoods were observed. The characteristic values of the cloud optical thickness were 0.1-0.3 at the early stage of the ACB formation in the solar longitude range Ls = 20-60°. After Ls = 93°, the well-developed ACB showed cloud optical thicknesses varying between 0.3 and 0.8. The ACB quickly decayed after Ls = 140°. Both polar hoods were observed during their development and decay stages, showing cloud optical thicknesses of about 0.35. The north polar hood started to develop at Ls = 160° and the south one at Ls = 330°. Estimates of water content in the ice clouds gave values of 0.35-1.8 gm-2 for ACB and 0.4 gm-2 for the polar hoods. A comparison with water vapor abundance showed that only a small fraction (10-20% for ACB and 30% for the polar hoods) of total water content in the atmosphere was accumulated in clouds. The Martian surface albedo at the wavelength 300 nm appeared very low (0.004-0.018) and exhibited anticorrelation with the visual albedo consistent with optical properties of iron oxides abundant in Martian soils. The investigation of a regional dust storm allowed the estimation of dust optical parameters at the wavelength 300 nm (asymmetry factor gd = 0.8 and single scattering albedo ? d = 0.6).

Mateshvili, Nina; Fussen, Didier; Vanhellemont, Filip; Bingen, Christine; Dodion, Jan; Montmessin, Franck; Perrier, Severine; Dimarellis, Emmanuel; Bertaux, Jean-Loup

2007-07-01

84

Results of multiband (L, S, Ku band) propagation measurements and model for high elevation angle land mobile satellite channel  

NASA Astrophysics Data System (ADS)

Signal propagation in the land mobile satellite (LMS) service is an important consideration due to its critical impact on the overall economic and commercial viability of the system. At frequencies allocated for LMS systems, shadowing of the line-of-sight (LOS) signal as well as multipath propagation phenomena can severely impair the link availability. In particular, as most of the studies have shown, the shadowing of LOS signal causes long and deep fades in a variety of mobile environments due to the inherent nature of the channel between the satellite and a mobile. Roadside obstacles, such as buildings, trees, utility poles etc., in the immediate vicinity of a mobile and the surrounding terrain are major sources of signal shadowing in LMS links. Therefore, a proper knowledge of link degradation is essential for cost-effective planning of a satellite based mobile communication system. The results of a propagation campaign undertaken to characterize the fading nature of LMS channel at high elevation angles is presented. It was envisaged that one of the most important physical variables contributing to the amount of LOS signal shadowing is the elevation angle of the satellite. At higher elevation angles to the satellite, less obstructions in the direct satellite-to-mobile path would therefore amount to statistically better link availability. Narrowband channel measurements were carried out at three RF frequencies corresponding to L (1.3 GHz), S (2.32/2.45 GHz), and Ku (10.4 GHz) bands. The campaign itself was divided into two phases to observe the effects of seasonal variation of foliage on the roadside trees. Phase measurements were carried out in September 1991 and in April 1992. Some important aspects from the statistical analysis of the propagation data are presented.

Parks, M. A. N.; Butt, G.; Evans, Barry G.; Richharia, M.

1993-08-01

85

Results of multiband (L, S, Ku band) propagation measurements and model for high elevation angle land mobile satellite channel  

NASA Technical Reports Server (NTRS)

Signal propagation in the land mobile satellite (LMS) service is an important consideration due to its critical impact on the overall economic and commercial viability of the system. At frequencies allocated for LMS systems, shadowing of the line-of-sight (LOS) signal as well as multipath propagation phenomena can severely impair the link availability. In particular, as most of the studies have shown, the shadowing of LOS signal causes long and deep fades in a variety of mobile environments due to the inherent nature of the channel between the satellite and a mobile. Roadside obstacles, such as buildings, trees, utility poles etc., in the immediate vicinity of a mobile and the surrounding terrain are major sources of signal shadowing in LMS links. Therefore, a proper knowledge of link degradation is essential for cost-effective planning of a satellite based mobile communication system. The results of a propagation campaign undertaken to characterize the fading nature of LMS channel at high elevation angles is presented. It was envisaged that one of the most important physical variables contributing to the amount of LOS signal shadowing is the elevation angle of the satellite. At higher elevation angles to the satellite, less obstructions in the direct satellite-to-mobile path would therefore amount to statistically better link availability. Narrowband channel measurements were carried out at three RF frequencies corresponding to L (1.3 GHz), S (2.32/2.45 GHz), and Ku (10.4 GHz) bands. The campaign itself was divided into two phases to observe the effects of seasonal variation of foliage on the roadside trees. Phase measurements were carried out in September 1991 and in April 1992. Some important aspects from the statistical analysis of the propagation data are presented.

Parks, M. A. N.; Butt, G.; Evans, Barry G.; Richharia, M.

1993-01-01

86

The Inference of Atmospheric Ozone Using Satellite Nadir Measurements in the 1042/CM Band.  

National Technical Information Service (NTIS)

A description and detailed analysis of a technique for inferring atmospheric ozone information from satellite nadir measurements in the 1042 cm band are presented. A method is formulated for computing the emission from the lower boundary under the satelli...

J. M. Russell S. R. Drayson

1973-01-01

87

TES/Aura L2 Water Vapor (H2O) Nadir (TL2H2ONS)  

... Data and Information   TES/Aura L2 Water Vapor (H2O) Nadir (TL2H2ONS) News:  TES News Join TES ... Data: TES Order Tool Parameters:  H2O Volume Mixing Ratio Precision Vertical Resolution Order ...

2014-07-03

88

KaRIn on SWOT: modeling and simulation of near-nadir Ka-band interferometric SAR images  

NASA Astrophysics Data System (ADS)

The principal instrument of the wide-swath altimetry mission SWOT is KaRIn, a Ka-band interferometric SAR system operating on near-nadir swaths on both sides of the satellite track. Due to the short wavelength and particular observation geometry, there are very limited reports on the backscattering from natural surfaces. Simulators that cover both radiometric and geometric aspects are therefore developed in the framework of the CNES phase 0 and A studies of SWOT. This article presents the modeling and simulation approaches that have been adopted, and shows some preliminary simulation results.

Fjørtoft, Roger; Koudogbo, Fifamè; Duro, Javier; Ruiz, Christian; Gaudin, Jean-Marc; Mallet, Alain; Pourthie, Nadine; Lion, Christine; Ordoqui, Patrick; Arnaud, Alain

2010-10-01

89

LV filling pressure during PEEP measured by nadir wedge pressure after airway disconnection.  

PubMed

Pulmonary arterial occlusion pressure (Ppao) may not accurately reflect left ventricular filling pressure (LVFP) during ventilation with positive end-expiratory pressure (PEEP) because increases in pleural pressure (Ppl) increase measured intrathoracic vascular and cardiac chamber pressures relative to atmospheric while decreasing LVFP by decreasing venous return. Steady-state values of Ppao off PEEP are not useful in understanding the hemodynamics on PEEP because of changes in blood volume distribution and ventricular afterload associated with the removal of PEEP. We hypothesized that changes in Ppao immediately after abrupt airway disconnection from PEEP selectively reflect removal of PEEP-associated Ppl changes prior to other physiological changes. In pentobarbital-anesthetized closed-chest dogs, we compared absolute left atrial pressure and left atrial pressure relative to Ppl (Platm) prior to abrupt disconnection from 15 cmH2O PEEP (on-PEEP), with Ppao at its nadir (nadir Ppao) following airway disconnection in three sequential conditions: control (normal), after propranolol-induced acute ventricular failure, and after oleic acid-induced lung injury. For all conditions at low LVFP (less than 9 Torr), nadir Ppao reflects Platm better than on-PEEP Ppao, while at higher LVFP (greater than 9 Torr), on-PEEP Ppao better reflects Platm than nadir Ppao (P less than 0.05). Accurate predictions of on-PEEP Platm can be made using both on-PEEP and nadir Ppao values in a multiple regression equation. PMID:3901780

Carter, R S; Snyder, J V; Pinsky, M R

1985-10-01

90

Note on the Effect of Horizontal Gradients for Nadir-Viewing Microwave and Infrared Sounders  

NASA Technical Reports Server (NTRS)

Passive microwave and infrared nadir sounders such as the Advanced Microwave Sounding Unit A (AMSU-A) and the Atmospheric InfraRed Sounder (AIRS), both flying on NASA s EOS Aqua satellite, provide information about vertical temperature and humidity structure that is used in data assimilation systems for numerical weather prediction and climate applications. These instruments scan cross track so that at the satellite swath edges, the satellite zenith angles can reach approx. 60 deg. The emission path through the atmosphere as observed by the satellite is therefore slanted with respect to the satellite footprint s zenith. Although radiative transfer codes currently in use at operational centers use the appropriate satellite zenith angle to compute brightness temperature, the input atmospheric fields are those from the vertical profile above the center of the satellite footprint. If horizontal gradients are present in the atmospheric fields, the use of a vertical atmospheric profile may produce an error. This note attempts to quantify the effects of horizontal gradients on AIRS and AMSU-A channels by computing brightness temperatures with accurate slanted atmospheric profiles. We use slanted temperature, water vapor, and ozone fields from data assimilation systems. We compare the calculated slanted and vertical brightness temperatures with AIRS and AMSU-A observations. We show that the effects of horizontal gradients on these sounders are generally small and below instrument noise. However, there are cases where the effects are greater than the instrument noise and may produce erroneous increments in an assimilation system. The majority of the affected channels have weighting functions that peak in the upper troposphere (water vapor sensitive channels) and above (temperature sensitive channels) and are unlikely t o significantly impact tropospheric numerical weather prediction. However, the errors could be significant for other applications such as stratospheric analysis. Gradients in ozone and tropospheric temperature appear to be well captured by the analyses. In contrast, gradients in upper stratospheric and mesospheric temperature as well as upper tropospheric humidity are less well captured. This is likely due in part to a lack of data to specify these fields accurately in the analyses. Advanced new sounders, like AIRS, may help to better specify these fields in the future.

Joiner, J.; Poli, P.

2004-01-01

91

Vertical information content of nadir measurements of tropospheric NO2 from satellite  

NASA Astrophysics Data System (ADS)

When applying satellite measurements in atmospheric pollution research, one commonly used species are tropospheric NO2 columns. They can be useful for the identification and evaluation of natural and anthropogenic NOx emissions and their changes over time as well as for process studies and for the investigation of atmospheric transport events. However, the lack of vertical resolution is one major limitation of the commonly used DOAS retrievals of NO2 columns from satellite observed radiances. Combined with the altitude-dependence of retrieval sensitivity, this entails the use of a priori information on the NO2 vertical profile. This significantly contributes to the retrieval uncertainties, which could be reduced if information on the vertical location of the NO2 could be retrieved from the measurements themselves. In this study, we investigate the vertical information content of nadir NO2 observations in the UV/visible wavelength range. For this purpose, we revisit the vertical sensitivity of DOAS retrievals of NO2, which is encoded in the averaging kernels, and contrast these findings with the results from a formal solution to the inverse radiative transfer problem, using synthetic spectra representing measurements over polluted regions. As a result, we can show that in certain cases, it is indeed possible to derive information on the vertical distribution of NO2 from the DOAS analysis alone, reducing the dependence of the retrievals on a priori information in these situations.

Hilboll, Andreas; Richter, Andreas; Burrows, John P.

2014-05-01

92

Six years of total ozone column measurements from SCIAMACHY nadir observations  

NASA Astrophysics Data System (ADS)

Total O3 columns have been retrieved from six years of SCIAMACHY nadir UV radiance measurements using SDOAS, an adaptation of the GDOAS algorithm previously developed at BIRA-IASB for the GOME instrument. GDOAS and SDOAS have been implemented by the German Aerospace Center (DLR) in the version 4 of the GOME Data Processor (GDP) and in version 3 of the SCIAMACHY Ground Processor (SGP), respectively. The processors are being run at the DLR processing centre on behalf of the European Space Agency (ESA). We first focus on the description of the SDOAS algorithm with particular attention to the impact of uncertainties on the reference O3 absorption cross-sections. Second, the resulting SCIAMACHY total ozone data set is globally evaluated through large-scale comparisons with results from GOME and OMI as well as with ground-based correlative measurements. The various total ozone data sets are found to agree within 2% on average. However, a negative trend of 0.2-0.4%/year has been identified in the SCIAMACHY O3 columns; this probably originates from instrumental degradation effects that have not yet been fully characterized.

Lerot, C.; van Roozendael, M.; van Geffen, J.; van Gent, J.; Fayt, C.; Spurr, R.; Lichtenberg, G.; von Bargen, A.

2008-11-01

93

Six years of total ozone column measurements from SCIAMACHY nadir observations  

NASA Astrophysics Data System (ADS)

Total O3 columns have been retrieved from six years of SCIAMACHY nadir UV radiance measurements using SDOAS, an adaptation of the GDOAS algorithm previously developed at BIRA-IASB for the GOME instrument. GDOAS and SDOAS have been implemented by the German Aerospace Center (DLR) in the version 4 of the GOME Data Processor (GDP) and in version 3 of the SCIAMACHY Ground Processor (SGP), respectively. The processors are being run at the DLR processing centre on behalf of the European Space Agency (ESA). We first focus on the description of the SDOAS algorithm with particular attention to the impact of uncertainties on the reference O3 absorption cross-sections. Second, the resulting SCIAMACHY total ozone data set is globally evaluated through large-scale comparisons with results from GOME and OMI as well as with ground-based correlative measurements. The various total ozone data sets are found to agree within 2% on average. However, a negative trend of 0.2-0.4%/year has been identified in the SCIAMACHY O3 columns; this probably originates from instrumental degradation effects that have not yet been fully characterized.

Lerot, C.; van Roozendael, M.; van Geffen, J.; van Gent, J.; Fayt, C.; Spurr, R.; Lichtenberg, G.; von Bargen, A.

2009-04-01

94

Preliminary results from a subsonic high-angle-of-attack flush airdata sensing (HI-FADS) system - Design, calibration, algorithm development, and flight test evaluation  

NASA Technical Reports Server (NTRS)

A nonintrusive high angle-of-attack flush airdata sensing (HI-FADS) system was installed and flight-tested on the F-18 high alpha research vehicle. This paper discusses the airdata algorithm development and composite results expressed as airdata parameter estimates and describes the HI-FADS system hardware, calibration techniques, and algorithm development. An independent empirical verification was performed over a large portion of the subsonic flight envelope. Test points were obtained for Mach numbers from 0.15 to 0.94 and angles of attack from -8.0 to 55.0 deg. Angles of sideslip ranged from -15.0 to 15.0 deg, and test altitudes ranged from 18,000 to 40,000 ft. The HI-FADS system gave excellent results over the entire subsonic Mach number range up to 55 deg angle of attack. The internal pneumatic frequency response of the system is accurate to beyond 10 Hz.

Whitmore, Stephen A.; Moes, Timothy R.; Larson, Terry J.

1990-01-01

95

Simultaneous ocean cross-section and rainfall measurements from space with a nadir pointing radar  

NASA Technical Reports Server (NTRS)

A modified version of the surface-target-attenuation radar described by Meneghini et al. (1983) is proposed which permits simultaneous measurement of ocean radar cross sections and path-average rain rates using a nadir-pointing satellite-borne microwave radar. The basic concept is explained and illustrated; the equations describing the data reduction are derived; some preliminary numerical computations based on a 7.5-m-diameter 10-kW 1.33-microsec-pulse radar operating at 1.87 cm from an altitude of 500 km are performed; and the major error sources (mismatches between rain scattering volumes and additional multipath contributions) and limitations (nadir pointing) are discussed. It is suggested that the system could provide a nadir calibration for wide-swath observing systems such as scanning microwave radiometers.

Atlas, D.; Meneghini, R.

1983-01-01

96

In-flight flow visualization results from the X-29A aircraft at high angles of attack  

NASA Technical Reports Server (NTRS)

Flow visualization techniques were used on the X-29A aircraft at high angles of attack to study the vortical flow off the forebody and the surface flow on the wing and tail. The forebody vortex system was studied because asymmetries in the vortex system were suspected of inducing uncommanded yawing moments at zero sideslip. Smoke enabled visualization of the vortex system and correlation of its orientation with flight yawing moment data. Good agreement was found between vortex system asymmetries and the occurrence of yawing moments. Surface flow on the forward-swept wing of the X-29A was studied using tufts and flow cones. As angle of attack increased, separated flow initiated at the root and spread outboard encompassing the full wing by 30 deg angle of attack. In general, the progression of the separated flow correlated well with subscale model lift data. Surface flow on the vertical tail was also studied using tufts and flow cones. As angle of attack increased, separated flow initiated at the root and spread upward. The area of separated flow on the vertical tail at angles of attack greater than 20 deg correlated well with the marked decrease in aircraft directional stability.

Delfrate, John H.; Saltzman, John A.

1992-01-01

97

Comparison of OClO Nadir Measurements from SCIAMACHY and GOME  

NASA Astrophysics Data System (ADS)

The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography was launched successfully onboard ENVISAT on March 1, 2002. It observes the solar radiation transmitted, backscattered from the atmosphere and reflected from the ground in nadir, limb and occultation viewing modes. Chlorinedioxide (OClO), an important indicator for stratospheric chlorine activation, can be measured in the UV spectral range by Differential Optical Absorption Spectroscopy (DOAS). First results of the DOAS retrieval of OClO slant column densities (SCDs) from the SCIAMACHY measurements are presented and compared to measurements of the Global Ozone Monitoring Experiment (GOME) which has successfully measured OClO since 1995. SCIAMACHY flies in the same orbit, but measures approx. 30 minutes earlier than GOME. As OClO shows a strong diurnal variation, this leads to differences in the observed column densities, which may be useful to investigate the photochemistry of OClO and related compounds. Also, the spatial resolution of SCIAMACHY is higher (30*60 km2 compared to 40*320 km2 for GOME), which will allow a more detailed study of small scale effects like e.g. chlorine activation in mountain waves.

Kühl, S.; Wilms-Grabe, W.; Frankenberg, C.; Grzegorski, M.; Platt, U.; Wagner, T.

98

Accuracy of vertical air motions from nadir-viewing Doppler airborne radars  

NASA Technical Reports Server (NTRS)

This paper presents an analysis of the uncertainties expected in vertical velocities using a vertically pointing airborne Doppler radar which has a nadir or zenith-pointing beam. To examine the expected uncertainty, the Doppler velocity equation for a moving platform is derived and it is applied to cases of nadir-fixed and stabilized beams. The main emphasis of the paper is on the effect of platform stability on the deduced vertical air motions and it is shown that the antenna must be stabilized to obtain desired accuracy in the vertical velocity measurements.

Heymsfield, Gerald M.

1989-01-01

99

Complexities of nadir-looking radiometric temperature measurements of plant canopies  

NASA Technical Reports Server (NTRS)

Effective radiant temperatures (ERTs) of five wheat canopies in different stages of development were measured during morning and noon periods. The observed variability in nadir sensor response was quantitatively described as a function of canopy structure and the vertical temperature profile of canopy components. In many cases, the nadir sensor ERT was a poor measure of vegetation temperature due to effects of soil emissions. Strong vertical temperature profiles of vegetation components were also observed. The theory and measurements presented document that remote measurements of vegetation canopy temperatures cannot be made indiscriminately over large spatial regions without consideration of the underlying physical principles.

Kimes, D. S.; Idso, S. B.; Pinter, P. J., Jr.; Jackson, R. D.; Reginato, R. J.

1980-01-01

100

Combined Wind Vector and Sea State Impact on Ocean Nadir-Viewing Ku- and C-Band Radar Cross-Sections  

PubMed Central

The authors report the first results in studying the polarization anisotropy of the microwave backscatter from nadir observations provided by Jason-1 altimeter in both Ku- and C-band. A small but clear wind direction signal for wind speeds above 6 m/s is revealed. These azimuthal variations of radar cross-section increase with increasing wind speed up to 14 m/s. The signatures then level off at higher winds. These results extend, for the first time, recent theoretical improved scattering approximation, and point some similarities between scattering and emission mechanisms at nadir. The observed directional effect can thus be interpreted as a signature of the curvature anisotropy of wind-generated short-scale waves. Sensitivities to both wind speed and sea state are also reported in the present analysis.

Tran, Ngan; Chapron, Bertrand

2006-01-01

101

OH line selection for nadir airglow gravity wave imaging in the auroral zone  

Microsoft Academic Search

For satellite borne nadir OH airglow wave imaging in the auroral zone the observed lines must be strong enough to give good signal to noise, coincident with strong atmospheric absorption lines to suppress structure in the image due to reflection of airglow and moonlight from tops of clouds and from high altitude terrain, and in a spectral region coincident with

J. B. Kumer; J. Hecht; T. R. Geballe; J. L. Mergenthaler; M. Rinaldi; E. S. Claflin; G. R. Swenson

2003-01-01

102

NADIR (Network Anomaly Detection and Intrusion Reporter): A prototype network intrusion detection system  

Microsoft Academic Search

The Network Anomaly Detection and Intrusion Reporter (NADIR) is an expert system which is intended to provide real-time security auditing for intrusion and misuse detection at Los Alamos National Laboratory's Integrated Computing Network (ICN). It is based on three basic assumptions: that statistical analysis of computer system and user activities may be used to characterize normal system and user behavior,

K. A. Jackson; D. H. DuBois; C. A. Stallings

1990-01-01

103

OSRMS (Ocean Surface Roughness Measurement System): The DREP (Defence Research Establishment Pacific) Near-Nadir Scatterometer.  

National Technical Information Service (NTIS)

The ocean surface roughness measurement system (OSRMS) is a near-nadir-directed infrared (IR) scatterometer. It has been used to measure ocean-surface parameters and particularly for the examination from an aircraft of internal waves. This paper gives a d...

B. A. Hughes L. C. Pempel S. J. Hughes

1988-01-01

104

Endoscopic fenestration of a cerebellopontine angle arachnoid cyst resulting in complete recovery from sensorineural hearing loss and facial nerve palsy.  

PubMed

Cerebellopontine angle arachnoid cysts are usually asymptomatic, but are frequently found incidentally because of increased use of neuroimaging. Nevertheless, as these cysts enlarge, they may compress surrounding structures and cause neurological symptoms. Patients may present with vague, nonspecific symptoms such as headache, nausea, vomiting, and vertigo. Cranial nerve palsies, including sensorineural hearing loss and facial weakness, although rare, have also been reported in association with posterior fossa arachnoid cysts. Although surgery for these entities is controversial, arachnoid cysts can be treated surgically with open craniotomy for cyst removal, fenestration into adjacent arachnoid spaces, shunting of cyst contents, or endoscopic fenestration. Reversal of sensorineural hearing loss following open craniotomy treatment has been described in the literature in only 1 adult and 1 pediatric case. Improvement in facial weakness has also been reported after open craniotomy and arachnoid cyst fenestration. The authors report the first case of complete recovery from sensorineural hearing loss and facial weakness following endoscopic fenestration in a patient with a cerebellopontine angle arachnoid cyst. PMID:21284461

Olaya, Joffre E; Ghostine, Michelle; Rowe, Mark; Zouros, Alexander

2011-02-01

105

Photometric Characteristics of Sprites and Elves Derived from JEM-GLIMS Nadir Observations (Invited)  

NASA Astrophysics Data System (ADS)

The main goal of the JEM-GLIMS mission is to identify the horizontal structures of Transient Luminous Events (TLEs) and spatiotemporal relationship between TLEs and their parent lightning discharges based on the nadir observations from the International Space Station (ISS). For this purpose JEM-GLIMS equips two sets of optical instruments (LSI: CMOS camera, and PH: spectrophotometers) and two sets of radio wave receivers (VLFR: VLF receiver, and VITF: VHF interferometer). As all these instruments are installed at the bottom plane of the bus module facing to the Earth, JEM-GLIMS can carry out the nadir observations continuously. JEM-GLIMS was launched by HTV3 and was successfully installed at the exposed facility of the Japanese Experiment Module (JEM) on August 9, 2012. After the initial checkout operations, JEM-GLIMS finally started continuous observations on November 20, 2012. In the period from November 20, 2012 to June 30, 2013, totally 1597 transient optical events related to lightning flashes and/or TLE emissions were detected by the optical instruments. In 578 of these events, both LSI and PH detected clear transient optical signals well above the noise level. In order to derive sprite events from the detected transient optical events, we analyzed PH light-curve data first and estimated the peak irradiance related to the transient optical flashes. Then, we compared these intensities with the atmospheric transmittance. Finally, LSI image data are examined to clarify the morphological properties of the optical emission. We analyzed a transient optical event detected at 00:56:29.198 UT on December 15, 2012. The peak intensities of PH channels are estimated to be 1.4E-2 W/m2 (150-280 nm), 2.3E-4 W/m2 (316 nm), 5.9E-4 W/m2 (337 nm), 4.0E-4 W/m2 (392 nm), 4.2E-4 W/m2 (762 nm), and 6.3E-2 W/m2 (600-900 nm), respectively. It is found that all these intensities are significantly stronger than the lightning emission affected by the atmospheric transmittance. This fact implies that the light sources exist not only in the troposphere but also in the mesosphere. At the image data obtained by the narrow-band filter camera (LSI-2), a pancake structure with bright spots was confirmed. Thus, we attributed the pancake structure and bright spots to a sprite halo and sprite streamers, respectively. We further analyzed a transient optical event obtained at 01:41:00.466 UT on March 30, 2013. In this event very strong pulse signals are detected only by PH1 (150-280 nm) and PH4 (600-900 nm). Since the field-of-view (FOV) of PH4 is 86.8 deg., which is larger than that of other PH channels (FOV=42.7 deg.), a lightning discharge seems to be occurred within PH4 FOV but without FOV of the other PH channels. Nevertheless, the existence of the strong FUV emission detected by PH1 means the occurrence of elves. At the presentation, we will show the results derived from LSI and PH data analysis and will discuss the photometric characteristics more in detail.

Sato, M.; Takahashi, Y.; Adachi, T.; Kobayashi, N.; Mihara, M.; Ushio, T.; Morimoto, T.; Suzuki, M.; Yamazaki, A.; Inan, U.; Linscott, I.

2013-12-01

106

Preliminary results from a subsonic high angle-of-attack flush airdata sensing (HI-FADS) system: Design, calibration, and flight test evaluation  

NASA Technical Reports Server (NTRS)

A nonintrusive high angle-of-attack flush airdata sensing (HI-FADS) system was installed and flight-tested on the F-18 high alpha research flight vehicle. The system is a matrix of 25 pressure orifices in concentric circles on the nose of the vehicle. The orifices determine angles of attack and sideslip, Mach number, and pressure altitude. Pressure was transmitted from the orifices to an electronically scanned pressure module by lines of pneumatic tubing. The HI-FADS system was calibrated and demonstrated using dutch roll flight maneuvers covering large Mach, angle-of-attack, and sideslip ranges. Reference airdata for system calibration were generated by a minimum variance estimation technique blending measurements from two wingtip airdata booms with inertial velocities, aircraft angular rates and attitudes, precision radar tracking, and meteorological analyses. The pressure orifice calibration was based on identifying empirical adjustments to modified Newtonian flow on a hemisphere. Calibration results are presented. Flight test results used all 25 orifices or used a subset of 9 orifices. Under moderate maneuvering conditions, the HI-FADS system gave excellent results over the entire subsonic Mach number range up to 55 deg angle of attack. The internal pneumatic frequency response of the system is accurate to beyond 10 Hz. Aerodynamic lags in the aircraft flow field caused some performance degradation during heavy maneuvering.

Whitmore, Stephen A.; Moes, Timothy R.; Larson, Terry J.

1990-01-01

107

Angle Dispersive X-ray Diffraction Beamline on Indus-2 Synchrotron Radiation Source: Commissioning and First Results  

NASA Astrophysics Data System (ADS)

Angle dispersive x-ray diffraction (ADXRD) is a basic non destructive tool for the determination of crystal structure. Energy tunability and high flux are added advantages in using synchrotron radiation (SR) source for ADXRD technique. We have installed an ADXRD beamline (BL-12) on Indus-2, the Indian synchrotron source. Indus-2 is a 2.5GeV, 300mA SR source. The beamline consists of a Si (311) crystal pair based double crystal monochromator with bendable focusing optics. The experimental station consists of a six circle diffractometer with scintillation detector and an image plate area detector. The beamline has been used for wide range of experiments like powder and single crystal diffraction; grazing incidence diffraction, x-ray absorption near edge structure, Anomalous XRD, high pressure XRD etc. The beamline is being utilized by users from Indian universities and research institutions.

Sinha, A. K.; Sagdeo, Archna; Gupta, Pooja; Upadhyay, Anuj; Kumar, Ashok; Singh, M. N.; Gupta, R. K.; Kane, S. R.; Verma, A.; Deb, S. K.

2013-03-01

108

What's Your Angle on Angles?  

ERIC Educational Resources Information Center

Although the nature of the research varies, as do concepts of angle, research in general supports the supposition that angle is a complex idea, best understood from a variety of perspectives. In fact, the concept of angle tends to be threefold, consisting of: (1) the traditional, static notion of two rays meeting at a common vertex; (2) the idea…

Browning, Christine A.; Garza-Kling, Gina; Sundling, Elizabeth Hill

2007-01-01

109

Posttreatment prostate-specific antigen nadir highly predictive of distant failure and death from prostate cancer  

Microsoft Academic Search

Purpose: To link posttreatment biochemical profiles to distant failure and cause-specific survival by assessing the relationship between posttreatment prostate-specific antigen (PSA) nadir and PSA doubling time (PSADT) with these outcome measures.Methods and Materials: A total of 615 men were treated at the Fox Chase Cancer Center between April 1989 and December 1995 with three-dimensional conformal radiotherapy alone (median dose 73

Alexandra L Hanlon; Hasmik Diratzouian; Gerald E Hanks

2002-01-01

110

Radiation physics and modelling for off-nadir satellite-sensing of non-Lambertian surfaces  

NASA Technical Reports Server (NTRS)

The primary objective of this paper is to provide a deeper understanding of the physics of satellite remote-sensing when off-nadir observations are considered. Emphasis is placed on the analysis and modeling of atmospheric effects and the radiative transfer of non-Lambertian surface reflectance characteristics from ground-level to satellite locations. The relative importance of spectral, spatial, angular, and temporal reflectance characteristics for satellite-sensed identification of vegetation types in the visible and near-infrared wavelength regions is evaluated. The highest identification value is attributed to angular reflectance signatures. Using radiative transfer calculations to evaluate the atmospheric effects on angular reflectance distributions of vegetation surfaces, atmosphere-invariant angular reflectance features such as the 'hot spot' and the 'persistent valley' are identified. A new atmospheric correction formalism for complete angular reflectance distributions is described. A sample calculation demonstrates that a highly non-Lambertian measured surface reflectance distribution can be retrieved from simulated satellite data in the visible and near infrared to within about 20 percent accuracy for almost all view directions up to 60 deg off-nadir. Thus the high value of angular surface reflectance characteristics (the 'angular signature') for satellite-sensed feature identification is confirmed, which provides a scientific basis for future off-nadir satellite observations.

Gerstl, S. A.; Simmer, C.

1986-01-01

111

Rifting in the Northern Tyrrhenian Sea: Results from a combined wide-angle and multichannel seismic study  

NASA Astrophysics Data System (ADS)

Extension in the continental lithosphere leads to the formation of rift basins or finally to passive continental margins where plates fully broke apart. The extensional processes at basins and passive margins are still not fully understood. One of the reasons is that the observed amount of crustal thinning is often much higher than the horizontal extension in the brittle upper crust that can be accounted by faulting. Moreover, conjugated margins are often observed to be asymmetric in tectonic style. Regarding these objective we present an analysis of two W-E striking multichannel- and wide-angle seismic sections from the Northern Tyrrhenian Sea. The new data were acquired onboard the Spanish R/V Sarmiento de Gamboa and Italian R/V Urania in spring 2010, within the framework of the MEDOC project. The lines cross the basin from the Corsica and Sardinia Margins towards the conjugated Latium and Campania Margins (Italy). The transects are divided in four zones distinguishable in tectonic style, velocity distribution, heat-flow and crustal thickness: 1) The deep sedimentary Corsica and Sardinia basins in the West which formed during Oligocene (~30 Ma) and reveal a fan-shaped sedimentary infill that is sealed by a Messinian erosional unconformity on top (~5-7 Ma). 2) Large rotated blocks bounding the deepest sub-basins along the entire transects and contain Messinian syn-tectonic sediments. 3) A zone of highly fractured continental crust broadens to the south and is indicated by a high number of faults and coincident with a velocity reduction. Furthermore, magmatic activity during Pliocene age in the southern line is evident in the southern line. 4) Flat summits at the Latium Margin indicate that this zone was above seal-level during rifting whereas the southern region was sub-sealevel. Faults cutting the seafloor indicate recent tectonic activity. To quantify the amount of horizontal extension we identified pre-, syn-, and post-tectonic sedimentary units in the northern line, calculated the relative extension factor by large faults as well as balancing the length of the pre-tectonic basement. The Messinian reflector can be well identified throughout both sections and is therefore an excellent time-marker within the syn-tectonic sequence. The syn-tectonic sequence is limited by a reflector of Pliocene age. The above lying Pleistocene to Quaternary sediment is undisturbed and identified as the post-tectonic sequence except for the eastern region to the South (CD-line). Tomography of first arrivals obtained from wide-angle seismic data reveals the crustal architecture and thickness of 17 km ± 1 km along the northern profile. We found that the crust east of the Corsica Basin towards the Latium Margin is horizontally stretched by ~30 % and thinned vertically by the same amount (?-factor=1.3). Along the MEDOC-CD line the crustal has thinned by a factor of 1.5 in the vicinity of the Sardinia Basin and thins to a maximum of 2.2 (11 km) towards the mainland of Italy. Whereas the northern region has apparently stretched symmetrically, the higher stretched southern transect builds a pair of asymmetric conjugated margins.

Möller, Stefan; Grevemeyer, Ingo; Ranero, Cesar R.; Berndt, Christian; Klaeschen, Dirk; Sallares, Valenti; Zitellini, Nevio; de Franco, Roberto

2013-04-01

112

Rifting in the Northern Tyrrhenian Sea: Results from a combined wide-angle and multichannel seismic study  

NASA Astrophysics Data System (ADS)

Extension in the continental lithosphere leads to the formation of rift basins or finally to passive continental margins where plates fully broke apart. The extensional processes at basins and passive margins are still not fully understood. One of the reasons is that the observed amount of crustal thinning is often much higher than the horizontal extension in the brittle upper crust that can be accounted by faulting. Regarding this objective we present an analysis of two W-E striking depth-migrated multichannel- and wide-angle seismic sections from the Northern Tyrrhenian Sea. The new data were acquired onboard the Spanish R/V Sarmiento de Gamboa and Italian R/V Uraniain spring 2010, within the framework of the MEDOC project. The lines cross the basin from the Corsica and Sardinia margins towards the conjugated Latium/Campania margins (Italy). Along the transects we found two distinct domains distinguishable in tectonic style, heat-flow and crustal thickness: 1) The deep sedimentary Corsica and Sardinia basins in the West which formation started in the Oligocene (~30 Ma) and reveal a fan-shaped sedimentary infill with the Messinian erosional unconformity on top (~5-7 Ma) and 2) rifted crystalline continental crust expressed by horst and graben structures towards the East. These two domains are separated by a deep reaching (~10 km) and westward dipping fault/thrust complex. To quantify the amount of horizontal extension we identified pre-, syn-, and post-tectonic sedimentary units in the northern line A-B (Figure 1), calculated the relative extension factor by large faults as well as balancing the length of the pre-tectonic basement. The Messinian reflector can be well identified throughout the complete section and is therefore an excellent time-marker within the syn-tectonic sequence. The syn-tectonic sequence is limited by a reflector of Pliocene age. The above lying Pleistocene to Quaternary sediments are undisturbed and identified as the post-tectonic sequence. Tomography of first arrivals obtained from refraction and wide-angle seismic data reveals the crustal architecture and thickness of 18 km ± 1 km along the northern profile. We found that the eastern domain is horizontally stretched by >= 30 % and thinned vertically by 40 %. However, we believe that many faults are overlooked due to the partly complexity of Messinian-Tortonian syn-tectonic sequences and that in this young stage of (back-arc) basin evolution the crust evolves in a uniform manner. In this work, we will present these combined seismic data sets and compare them with the C-D transect, which is located ~80 km further south and shows larger stretching factors. Map of the Northern Tyrrehnian Sea and locations of seismic transects.

Moeller, S.; Grevemeyer, I.; Ranero, C. R.; Berndt, C.; Klaeschen, D.; Sallares, V.; Zitellini, N.; de Franco, R.

2012-12-01

113

The structure of self-assembled monolayers of alkylsiloxanes on silicon: A comparison of results from ellipsometry and low-angle x-ray reflectivity  

Microsoft Academic Search

The thicknesses of C10-C18 alkylsiloxane monolayers on silicon-silicon dioxide substrates have been measured with ellipsometry and low-angle X-ray reflection. Although, for any given sample, thicknesses measured by the two methods agree to within experimental error, ellipsometric measurements are systematically larger by approximately 2 â«. This difference may result from variations in the sensitivity of the two techniques to the structure

Stephen R. Wasserman; George M. Whitesides; Ian M. Tidswell; Ben M. Ocko; Peter S. Pershan; John D. Axe

1989-01-01

114

Geosynchronous orbiting Nadir Etalon Sounding Spectrometer instrument concept for temperature, moisture and trace species, GeoNESS  

NASA Technical Reports Server (NTRS)

The paper describes the salient features of the Geosynchronous orbiting Nadir Etalon Sounding Spectrometer (GeoNESS) designed for applications from geosynchronous orbit for nadir sounding temperature, moisture, and trace species analyses in the troposphere and the lower stratosphere. Particular attention is given to the optics of GeoNESS, the optomechanical design, the cooling systems, the measurement approach used in GeoNESS, the channel selection, and the calibration considerations.

Kumer, J. B.; Sterritt, L. W.; Roche, A. E.; Morrow, H. E.; Willis, C. L.; Spradley, I. E.; Murray, D. O.; Shenk, W. E.; Susskind, J.

1992-01-01

115

Angle Hunting  

NSDL National Science Digital Library

In this activity, learners use a hand-made protractor to measure angles they find in playground equipment. Learners will observe that angle measurements do not change with distance, because they are distance invariant, or constant. Note: The "Pocket Protractor" activity should be done ahead as a separate activity (see related resource), but a standard protractor can be used as a substitute.

Exploratorium

2010-01-01

116

Film-cooling from holes with compound angle orientations. Part 1: Results downstream of two staggered rows of holes with 3d spanwise spacing  

NASA Astrophysics Data System (ADS)

Experimental results are presented that describe the development and structure of flow downstream of two staggered rows of film-cooling holes with compound angle orientations. With this configuration, holes are spaced 3d apart in the spanwise direction, inclined at 35 deg with respect to the test surface when projected into the streamwise/normal plane, and inclined at 30 deg with respect to the test surface when projected into the spanwise/normal plane. Results are presented for an injectant to free-stream density ratio near 1.0, and injection blowing ratios from 0.5 to 1.50. Comparisons are made with measurements from two other configurations to determine: (1) the effects of hole angle orientation for constant spanwise hole spacing, and (2) the effects of spanwise hole spacing when the hole angle orientation is maintained constant. Results from the first comparison show that the compound angle injection configuration provides significantly improved film-cooling protection compared to a simple angle configuration for the same spanwise hole spacing, normalized streamwise location x/d, and blowing ratio m, for x/d less than 60. At x/d greater than 60, spanwise-averaged adiabatic effectiveness data downstream of the two configurations generally cover about the same range. Results from the second comparison show that spanwise-averaged effectiveness values are 25 to 40 percent higher when 3d spanwise hole spacing is employed compared to 3.9d spanwise hole spacing for the same m and x/d, for x/d less than 40. At x/d greater than 40, differences between the two configurations range from 12 to 30 percent. Results from all configurations studied show that spanwise-averaged iso-energetic Stanton number ratios cover approximately the same range of values and show roughly the same trends, ranging between 1.0 and 1.25. In particular, St(sub j)/St(sub o) values increase with m at each x/d, and show little variation with x/d for each value of m tested.

Ligrani, P. M.; Wigle, J. M.; Ciriello, S.; Jackson, S. M.

1994-05-01

117

Film-cooling from holes with compound angle orientations. Part 2: Results downstream of a single row of holes with 6d spanwise spacing  

NASA Astrophysics Data System (ADS)

Experimental results are presented that describe the development and structure of flow downstream of a single row of film-cooling holes with compound angle orientations. With this configuration, holes are spaced 6d apart in the spanwise direction, inclined at 35 deg with respect to the test surface when projected into the streamwise/normal plane, and inclined at 30 deg with respect to the test surface when projected into the spanwise/normal plane. Results are presented for an injectant to free-stream density ratio near 1.0, and injection blowing ratios from 0.5 to 1.50. Comparisons are made with measurements from two other configurations to determine: (1) the effects of hole angle orientation for constant spanwise hole spacing, and (2) the effects of spanwise hole spacing when the hole angle orientation is maintained constant. Results from the first comparison show that the compound angle injection configuration provides significantly improved film-cooling protection compared to a simple angle configuration for the same spanwise hole spacing, normalized streamwise location x/d, and blowing ratio m, for x/d less than 30 when m = 0.50 and for x/d less than 60 when m = 1.0 and 1.5. At x/d greater than 60, spanwise-averaged adiabatic effectiveness data downstream of the two configurations generally cover about the same range. Results from the second comparison show that spanwise-averaged effectiveness values are 20 to 39 percent higher when 6d spanwise hole spacing is employed compared to 7.8d spanwise hole spacing for the same m and x/d, for x/d less than 60. When plotted in bar-eta/m versus Xl/s coordinates, spanwise-averaged film effectiveness data measured downstream of one and two rows of holes from all injection configurations tested show a reasonable collapse. For m values between 1 and 3, spanwise-averaged iso-energetic Stanton number ratios measured just downstream of one row of holes are lower than results measured just downstream of two rows of holes, which evidences greater mixing and higher turbulence levels when the injectant emerges from two rows of holes.

Ligrani, P. M.; Wigle, J. M.; Jackson, S. W.

1994-05-01

118

Simultaneous ocean cross section and rainfall measurements from space with a nadir-looking radar  

NASA Technical Reports Server (NTRS)

In the case of a nadir-looking spaceborne or aircraft radar in the presence of rain, the return power corresponding to secondary surface scattering may provide information on the properties of the surface and the precipitation. The object of the study is to evaluate a method for determining simultaneously the rainfall rate and the backscattering coefficient of the surface. The method is based upon the mirror-reflected power, which corresponds to the portion of the incident power scattered from the surface to the precipitation, intercepted by the precipitation, and again returned to the surface where it is scattered a final time back to the antenna.

Meneghini, Robert; Atlas, David

1986-01-01

119

Angle Measurer  

NSDL National Science Digital Library

This Flash applet gives students practice in creating an angle measuring between zero and 180 degrees. Two buttons control the increase or decrease of the opening between two rays. Points are awarded for accuracy.

2011-01-01

120

Right Angle  

NSDL National Science Digital Library

This article gives teachers background information on right angles. It provides geometric and practical examples, a paper folding construction method, and some history of the usage of the term 'right.'

Goldenberg, Paul

2011-06-09

121

First results of proton antiproton annihilation into a pion pair at large scattering angles within the handbag approach  

NASA Astrophysics Data System (ADS)

We propose to describe the process p bar p ? ?+ ?? in a perturbative, QCD motivated framework in which a hard ud?bar d ? d bar d annihilation factorizes from soft transition distribution amplitudes. We advocate that the scale allowing for this factorization is the large transverse momentum transfer. In our simplified model, in which the proton is considered as a (scalar)diqark-quark system, a transition distribution amplitude describes the non-perturbative transition of the proton to the meson by emission of a scalar, isoscalar ud-diquark and absorption of an antiquark (analogously for bar p ? ??). We model the transition distribution amplitudes as an overlap of light-cone wave functions and present first results for the differential cross section. This process will be measured by the PANDA experiment at GSI-FAIR.

Goritschnig, A. T.; Kofler, S.; Schweiger, W.

2014-04-01

122

Low speed rotary aerodynamics of F-18 configuration for 0 deg to 90 deg angle of attack: Test results and analysis  

NASA Technical Reports Server (NTRS)

Aerodynamic characteristics obtained in a rotational flow environment, utilizing a rotary balance located in the Langley Spin Tunnel, are discussed and presented in tabular form for a 1/10 scale F-18 airplane model. The rotational aerodynamic characteristics were established for the basic airplane, as well as the influence of control deflections and the contribution of airplane components, i.e., body, wing, leading edge extension, horizontal and vertical tails, on these characteristics up to 90 deg angle of attack. Spin equilibrium conditions predicted using the measured data are also presented and compared with spin model and full scale flight results.

Hultberg, R.

1984-01-01

123

Effect of sensor view angle on the assessment of agronomic traits by ground level hyper-spectral reflectance measurements in durum wheat under contrasting Mediterranean conditions  

Microsoft Academic Search

The objective of this work is to study the effect of changing the sensor view angle on spectral reflectance indices and their relationships with yield and other agronomic traits. Canopy reflectance spectra of 25 durum wheat genotypes were measured with a field spectroradiometer at two view angles, nadir and 30°, from anthesis to maturity in two years and two water

N. Aparicio; D. Villegas; C. Royo; J. Casadesus

2004-01-01

124

Multi-Angle Switched HIFU: A New Ultrasound Device for Controlled Non-Invasive Induction of Small Spherical Ablation Zones-Simulation and Ex-Vivo Results  

NASA Astrophysics Data System (ADS)

Current HIFU devices produce elongated elliptical lesions (cigar shaped) in a single energy deposition. This prohibits the effective use of HIFU in small animal research as well as in clinical treatment where small volumes of tissue surrounded by critical structures need to be destroyed. We developed an ultrasound ablation device that non-invasively creates spheroidal lesions of an arbitrary diameter of up to 1 cm in a depth of up to 5 cm. The device consists of two focused ultrasound transducers aimed to the ablation target volume from two directions at a 90 degree angle. The operation of the transducers is switched back and forth so that only one transducer is energized at a time. A transient analysis of this ablation approach was performed using coupled simulations of acoustical pressure distributions, resulting temperature distributions, and thermal dose deposited to soft tissue. A prototype of the device was developed and tested in-vitro in a phantom and later in ex-vivo experiments in pig liver. The experimental results agreed with the numerical simulations and confirmed the ability of the multi-angle switched HIFU (MASH) device to create small spheroidal lesions in soft tissue within 2 minutes without significantly affecting the surrounding tissues.

Novák, Petr; Jamshidi-Parsian, Azemat; Benson, Donny G.; Webber, Jessica S.; Moros, Eduardo G.; Shafirstein, Gal; Griffin, Robert J.

2009-04-01

125

Monitoring regional vegetation change using reflectance measurements from multiple solar zenith angles.  

PubMed

Many traditional models of vegetation canopy reflectance have commonly used one of two approaches. Either the canopy is assumed to consist of discrete objects of known reflectance and geometric-optics are then used to calculate shading effects, or, as in the turbid medium approach, the canopy is treated as a horizontally homogeneous layer of small elements of known optical properties and radiative transfer theory is used to calculate canopy reflectance. This paper examines the effect of solar zenith angle on the reflectance of red and near-infrared radiation from forests using a combination of these modelling approaches. Forests are first modelled as randomly spaced eucalypt crowns over a homogeneous understorey and the fractional coverage of four components: shaded and sunlit canopy and shaded and sunlit understorey are calculated. Reflectance from each fraction is then modelled for a range of solar zenith angles using the Verhoef SAIL model. The overall scene reflection as seen by a nadir viewing satellite sensor is compared for three forest types representing a gradient of crown density from open dry grassy woodlands to dense wetter closed forest with an understorey of mesophytic plants. Modelled trends in scene reflectance change are consistent with aircraft measurements carried out at three different solar zenith angles. Results indicate that an increase in both tree density and solar zenith angle leads to an increase in the dominance of shaded components. In the visible band, both the sparsely treed woodland and the medium density dry forest show similar trends to that predicted by a turbid medium model, however, the wet forest shows a less rapid decrease in reflectance with solar zenith angle. In the near-infrared band, as tree density increases from woodland to wet forest, overall scene reflectance shows increased departure from that modelled using the traditional assumption of smooth homogeneous canopies, changing from an increase with solar zenith angle for the woodland to a decrease with solar zenith angle for the forest types. PMID:11697672

Russell, M

2001-09-01

126

Robust Rotation Angle Estimator  

Microsoft Academic Search

The conventional method of estimating the rotation angle of a pattern using the principal axes is not suitable for circular symmetric patterns since their eigenvalues are similar in both directions. In the paper, a robust method of estimating a rotation angle using the phase information of Zernike moments is presented. The experimental results show that the proposed method estimates the

Whoi-yul Kim; Young-sung Kim

1999-01-01

127

Stable Angles of Slopes  

NSDL National Science Digital Library

In this activity, students use a box filled with sand to learn about factors controlling the angle of repose (the stable angle of a slope). They will will see what happens when slopes are oversteepened, and relate the experiment results to general understanding of instability of slopes.

128

Estimating Angles  

NSDL National Science Digital Library

This Flash game for one or two players gives students practice in estimating the size of angles. A circle and a radius pointing in a random direction are given. The student activates a second sweeping radius, which can move in either direction, and tries to stop it at the specified measure. Three difficulty levels control the range of angle measures. Points are awarded based on closeness of the estimate. The Teachers' Notes page includes suggestions for implementation, discussion questions, ideas for extension and support.

2007-06-01

129

Early-stage rifting of the northern Tyrrhenian Sea Basin: Results from a combined wide-angle and multichannel seismic study  

NASA Astrophysics Data System (ADS)

Extension of the continental lithosphere leads to the formation of rift basins and ultimately may create passive continental margins. The mechanisms that operate during the early stage of crustal extension are still intensely debated. We present the results from coincident multichannel seismic and wide-angle seismic profiles that transect across the northern Tyrrhenian Sea Basin. The profiles cross the Corsica Basin (France) to the Latium Margin (Italy) where the early-rift stage of the basin is well preserved. We found two domains, each with a distinct tectonic style, heat flow and crustal thickness. One domain is the Corsica Basin in the west that formed before the main rift phase of the northern Tyrrhenian Sea opening (˜8-4 Ma). The second domain is rifted continental crust characterized by tilted blocks and half-graben structures in the central region and at the Latium Margin. These two domains are separated by a deep (˜10 km) sedimentary complex of the eastern portion of the Corsica Basin. Travel-time tomography of wide-angle seismic data reveals the crustal architecture and a subhorizontal 15-17 ± 1 km deep Moho discontinuity under the basin. To estimate the amount of horizontal extension we have identified the pre-, syn-, and post-tectonic sedimentary units and calculated the relative displacement of faults. We found that major faults initiated at angles of 45°-50° and that the rifted domain is horizontally stretched by a factor of ? ˜ 1.3 (˜8-10 mm/a). The crust has been thinned from ˜24 to ˜17 km indicating a similar amount of extension (˜30%). The transect represents one of the best imaged early rifts and implies that the formation of crustal-scale detachments, or long-lived low-angle normal faults, is not a general feature that controls the rift initiation of continental crust. Other young rift basins, like the Gulf of Corinth, the Suez Rift or Lake Baikal, display features resembling the northern Tyrrhenian Basin, suggesting that half-graben formations and distributed homogeneous crustal thinning are a common feature during rift initiation.

Moeller, S.; Grevemeyer, I.; Ranero, C. R.; Berndt, C.; Klaeschen, D.; Sallares, V.; Zitellini, N.; Franco, R.

2013-08-01

130

Ozone ProfilE Retrieval Algorithm (OPERA) for nadir-looking satellite instruments in the UV-VIS  

NASA Astrophysics Data System (ADS)

For the retrieval of the vertical distribution of ozone in the atmosphere the Ozone ProfilE Retrieval Algorithm (OPERA) has been further developed. The new version (1.26) of OPERA is capable of retrieving ozone profiles from UV-VIS observations of most nadir-looking satellite instruments like GOME, SCIAMACHY, OMI and GOME-2. The setup of OPERA is described and results are presented for GOME and GOME-2 observations. The retrieved ozone profiles are globally compared to ozone sondes for the years 1997 and 2008. Relative differences between GOME/GOME-2 and ozone sondes are within the limits as specified by the user requirements from the Climate Change Initiative (CCI) programme of ESA (20% in the troposphere, 15% in the stratosphere). To demonstrate the performance of the algorithm under extreme circumstances, the 2009 Antarctic ozone hole season was investigated in more detail using GOME-2 ozone profiles and lidar data, which showed an unusual persistence of the vortex over the Río Gallegos observing station (51° S, 69.3° W). By applying OPERA to multiple instruments, a time series of ozone profiles from 1996 to 2013 from a single robust algorithm can be created.

van Peet, J. C. A.; van der A, R. J.; Tuinder, O. N. E.; Wolfram, E.; Salvador, J.; Levelt, P. F.; Kelder, H. M.

2014-03-01

131

Relative and Absolute Calibration of a Multihead Camera System with Oblique and Nadir Looking Cameras for a Uas  

NASA Astrophysics Data System (ADS)

Numerous unmanned aerial systems (UAS) are currently flooding the market. For the most diverse applications UAVs are special designed and used. Micro and mini UAS (maximum take-off weight up to 5 kg) are of particular interest, because legal restrictions are still manageable but also the payload capacities are sufficient for many imaging sensors. Currently a camera system with four oblique and one nadir looking cameras is under development at the Chair for Geodesy and Geoinformatics. The so-called "Four Vision" camera system was successfully built and tested in the air. A MD4-1000 UAS from microdrones is used as a carrier system. Light weight industrial cameras are used and controlled by a central computer. For further photogrammetric image processing, each individual camera, as well as all the cameras together have to be calibrated. This paper focuses on the determination of the relative orientation between the cameras with the „Australis" software and will give an overview of the results and experiences of test flights.

Niemeyer, F.; Schima, R.; Grenzdörffer, G.

2013-08-01

132

The application of near-nadir Delta-k radar techniques to geodetic altimetry and oceanographic remote sensing  

NASA Technical Reports Server (NTRS)

This paper first examines the extension of two-frequency, or Delta-k near-nadir remote sensing techniques to off-nadir radar altimetry. A different approach to sea state sensing is investigated which appears to offer much higher accuracy. The second section examines the Delta-k method of sensing rough surface area correlation or ocean wavenumber spectrum. The technique shows promise of directly sensing this parameter, in contrast with synthetic-aperture radar methods which are based on complex wave interaction mechanisms and mathematical transformations requiring the acquisition of voluminous data.

Miller, L. S.

1983-01-01

133

The inference of atmospheric ozone using satellite nadir measurements in the 1042/cm band  

NASA Technical Reports Server (NTRS)

A description and detailed analysis of a technique for inferring atmospheric ozone information from satellite nadir measurements in the 1042 cm band are presented. A method is formulated for computing the emission from the lower boundary under the satellite which circumvents the difficult analytical problems caused by the presence of atmospheric clouds and the watervapor continuum absorption. The inversion equations are expanded in terms of the eigenvectors and eigenvalues of a least-squares-solution matrix, and an analysis is performed to determine the information content of the radiance measurements. Under favorable conditions there are only two pieces of independent information available from the measurements: (1) the total ozone and (2) the altitude of the primary maximum in the ozone profile.

Russell, J. M., III; Drayson, S. R.

1973-01-01

134

The retrieval of cloud particle size distributions using occultation and nadir observation geometries  

NASA Astrophysics Data System (ADS)

High cirrus clouds have significant but complex effects on climate due to their capacity to reflect, absorb and emit radiation. Their radiative transfer properties depend on the size and shape of the ice particles of which they are composed. While particle shape information can be obtained only indirectly by space remote sensing, it is possible to obtain size information by direct inversion of remotely sensed optical spectra. Even this approach to the retrieval of particle size information for high-altitude ice clouds, however, remains a very challenging task for space remote sensing. In this presentation, we will discuss methods for the inversion of optical spectra to obtain particle size distributions in clouds. We will also report the application of these methods to space remote sensing measurements of high altitude cirrus clouds. The observations consist of broadband infrared spectra obtained by the ACE FT-IR spectrometer on the SciSat platform. The observation geometry used in the SciSat mission -solar occultation -is capable of good vertical resolution but does not permit the horizontal extent or geographical location of the clouds to be determined. Nadir observation geometries, on the other hand, can give precise geographical locations but are limited by poor signal to noise ratios due to the small thicknesses and low ice particle number densities of the clouds. In the presentation, we will also examine the relative advantages and disadvantages of retrieving cirrus cloud particle size information from both nadir and solar occultation observations and compare the expected signal intensities in each case.

Sloan, James; Hu, Jerry; Galkina, Irina; Sioris, Chris

135

Sun-view angle effects on reflectance factors of corn canopies  

NASA Technical Reports Server (NTRS)

The effects of sun and view angles on reflectance factors of corn (Zea mays L.) canopies ranging from the six leaf stage to harvest maturity were studied on the Purdue University Agronomy Farm by a multiband radiometer. The two methods of acquiring spectral data, the truck system and the tower systrem, are described. The analysis of the spectral data is presented in three parts: solar angle effects on reflectance factors viewed at nadir; solar angle effects on reflectance factors viewed at a fixed sun angle; and both sun and view angles effect on reflectance factors. The analysis revealed that for nadir-viewed reflectance factors there is a strong solar angle dependence in all spectral bands for canopies with low leaf area index. Reflectance factors observed from the sun angle at different view azimuth angles showed that the position of the sensor relative to the sun is important in determining angular reflectance characteristics. For both sun and view angles, reflectance factors are maximized when the sensor view direction is towards the sun.

Ranson, K. J.; Daughtry, C. S. T.; Biehl, L. L.; Bauer, M. E.

1985-01-01

136

Detection Method of Lightning and TLEs by JEM-GLIMS Nadir Observation  

NASA Astrophysics Data System (ADS)

A scientific payload named JEM-GLIMS aboard the International Space Station (ISS) is aimed at observing lightning and Transient Luminous Events (TLEs) globally. Keeping its field-of-view toward the nadir direction, GLIMS clarifies the horizontal structures of lightning and TLEs, which is a crucial issue to understand the electrodynamic coupling between the troposphere and ionosphere. A difficult point, however, is that careful analyses are necessary to separate the emissions of lightning and TLEs which spatially overlap along the line-of-sights in the case of nadir observation. In this study, we analyze the multi-wavelength optical data obtained by GLIMS to identify lightning and TLEs. The main data analyzed are those of imager (LSI) and spectrophotometer (PH). LSI consists of two cameras equipped with a broadband red filter and a narrowband 762-nm filter, respectively, and obtains imagery at a spatial resolution of 400 m/pixel on the ground surface. PH detects time-resolved emission intensity at a sampling rate of 20 kHz by six photometer channels measuring at 150-280, 337, 762, 600-900, 316 and 392 nm, respectively. During a period between November 2012 and June 2013, GLIMS observed 815 lightning and/or TLE events, and in 494 of them, both LSI and PH data showed clear signals above the noise level. As the first step, we carried out case study using an event observed at 09:50:47UT on Jan 29 2013 which did not cause strong saturation on the LSI and PH data. The estimated peak irradiance was 1.38x10^(-3) W/m^(2) at 600-900 nm, which is equivalent to the top 10 % bright lightning events observed by FORTE satellite in the past. This finding suggests that GLIMS selectively observes the most optically-powerful events. The peak irradiance was estimated also for the other PH channels. At all visible channels other than a far ultra violet (FUV) channel, the peak irradiance was estimated to be in good agreement with the atmospheric transmittance curve calculated between 10 km and ISS altitude. We therefore primarily attribute the visible emissions of this event to lightning discharge occurring in the troposphere. Interestingly, GLIMS also detected the FUV emission which is significantly stronger than that expected for tropospheric lightning. This finding suggests that TLE also occurred at higher altitudes where the FUV emission is not affected by atmospheric attenuation. As such, it is clear that GLIMS is able to discriminate optical emissions of lightning and TLEs occurring in the nadir direction. In the conference, we will examine the identification technique in details and, by applying it to all the events, will discuss the validity and limitation.

Adachi, T.; Sato, M.; Ushio, T.; Yamazaki, A.; Suzuki, M.; Masayuki, K.; Takahashi, Y.; Inan, U.; Linscott, I.; Hobara, Y.

2013-12-01

137

OH line selection for nadir airglow gravity wave imaging in the auroral zone  

NASA Astrophysics Data System (ADS)

For satellite borne nadir OH airglow wave imaging in the auroral zone the observed lines must be strong enough to give good signal to noise, coincident with strong atmospheric absorption lines to suppress structure in the image due to reflection of airglow and moonlight from tops of clouds and from high altitude terrain, and in a spectral region coincident with relatively weak aurora that its contribution to the observed structure can be corrected by data obtained in a guard band containing relatively strong auroral emission, and relatively weak, or no airglow. OH airglow spectra observed from high altitude, in our case Mauna Kea by the UKIRT CGS4 grating instrument, (see website http://www.jach.hawaii.edu/JACpublic/UKIRT/instruments/cgs4/maunakea/ohlines.html) provide an opportunity to identify lines that ARE NOT observed at that high altitude. These are most absorbed in the earths atmosphere. These occur in the regions near 1400 and 1900 nm of strong water vapor absorption. Our preliminary determination is that the 7-5 p1(2) line at 1899.01 nm and the p1(3) at 1911.41 nm are the best candidates. These are missing in the observed spectra, and this is confirmed by running FASCODE transmission calculations from top of Mauna Kea to space at .01 cm-1 resolution. Similar calculations for conditions at which the high resolution Kitt peak atlas data were taken confirmed the calculations. OH line positions and relative strengths within the band were derived from the HITRAN data base, and transmitted lines in the 7-5 band were used to determine the strength of these lines. Each are the order 10 kR, and are about four to six times brighter than atmospheric absorbed candidate lines in the 1400 nm region. Also, the aurora in the 1900nm region is considerably weaker than in the 1400nm region. In fact the region 1351 to 1358 contains relatively strong aurora, and practically no airglow, and is candidate for an instrumental auroral guard band. The nadir imaging instrument which utilizes a radiatively cooled near infrared two dimensional array detector will be described.

Kumer, J. B.; Hecht, J.; Geballe, T. R.; Mergenthaler, J. L.; Rinaldi, M.; Claflin, E. S.; Swenson, G. R.

2003-04-01

138

Results of a study of Mach number and Reynolds number effects on the lee side vortex flow field characteristics of an ogive-cylinder-frustum-cylinder at angles of attack to 25 degrees, volume 1  

NASA Technical Reports Server (NTRS)

An experimental program was conducted to survey the lee side vortex flow field about an ogive-cylinder-frustum-cylinder at angles of attack to 25 degrees for two Reynolds numbers at Mach number 0.8, and one Reynolds number at Mach number 1.96. The data were obtained using miniature 5-port conical pressure probes calibrated for angle of attack and roll angle over a Mach number range of 0.6 to 3.0. The results are presented here as local flow field properties and circulation strengths for various body stations.

Foley, J. E.

1972-01-01

139

Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar  

NASA Technical Reports Server (NTRS)

This paper presents observations of deep convection characteristics in the tropics and subtropics that have been classified into four categories: tropical cyclone, oceanic, land, and sea breeze. Vertical velocities in the convection were derived from Doppler radar measurements collected during several NASA field experiments from the nadir-viewing high-altitude ER-2 Doppler radar (EDOP). Emphasis is placed on the vertical structure of the convection from the surface to cloud top (sometimes reaching 18-km altitude). This unique look at convection is not possible from other approaches such as ground-based or lower-altitude airborne scanning radars. The vertical motions from the radar measurements are derived using new relationships between radar reflectivity and hydrometeor fall speed. Various convective properties, such as the peak updraft and downdraft velocities and their corresponding altitude, heights of reflectivity levels, and widths of reflectivity cores, are estimated. The most significant findings are the following: 1) strong updrafts that mostly exceed 15 m/s, with a few exceeding 30 m/s, are found in all the deep convection cases, whether over land or ocean; 2) peak updrafts were almost always above the 10-km level and, in the case of tropical cyclones, were closer to the 12-km level; and 3) land-based and sea-breeze convection had higher reflectivities and wider convective cores than oceanic and tropical cyclone convection. In addition, the high-resolution EDOP data were used to examine the connection between reflectivity and vertical velocity, for which only weak linear relationships were found. The results are discussed in terms of dynamical and microphysical implications for numerical models and future remote sensors.

Heymsfield, Gerald M.; Tian, Lin; Heymsfield, Andrew J.; Li, Lihua; Guimond, Stephen

2010-01-01

140

Observation of planetary boundary layer sulphur dioxide in the Norilsk region (Arctic) from the nadir thermal infrared IASI sounder (Invited)  

NASA Astrophysics Data System (ADS)

Norilsk is one of the most polluted places in the world, largely because of intense mining of heavy metals in the area. Here we report four years (2008-2011) of space-based SO2 measurements in the planetary boundary layer (PBL) of Norilsk. Both time series and spatial distributions of this city's main atmospheric gaseous pollutant are presented. If time allows it, a first estimation of total emissions and atmospheric lifetime of SO2 in the area will be provided, and a preliminary comparison with correlative measurements will be presented. Measurements used for this study were obtained from satellite observations of the Infrared Atmospheric Sounding Interferometer (IASI), the nadir thermal infrared (TIR) sounder onboard the MetOp platforms, which covers the Earth globally twice a day. TIR sounders are traditionally thought of as having poor sensitivity to the lowest part of the atmosphere. However, it has been recently demonstrated that elevated thermal contrast between the surface and the air above, allows retrieving trace gases present in the PBL such as e. g. ammonia. Here we show that PBL sounding of SO2 is possible in Norilsk due to the existence of large temperature inversions and associated negative thermal contrasts in wintertime. This work is the first large scale demonstration of the possibility of measuring boundary layer SO2 with space-based TIR sounders. These TIR measurements complement those of UV/Vis instruments, notably because the latter are limited by the availability of solar radiation at such high latitudes. The obtained results open new perspectives for the monitoring of air quality, by extending the work to other pollutants (CO, O3,...). Spatial distribution of the average retrieved 0-2 km column of SO2 over the Norilsk region for February 2009, expressed in Dobson Units.

Bauduin, S.; Clarisse, L.; Hurtmans, D.; Clerbaux, C.; Coheur, P.

2013-12-01

141

Nadir CD4+, religion, antiretroviral therapy, incidence of type 2 diabetes mellitus, and increasing rates of obesity among black Africans with HIV disease  

PubMed Central

Background: The purpose of this study was to determine the cross-sectional association between some sociodemographic factors and antiretroviral therapy (ART), as well as the incidence and predictors of type 2 diabetes mellitus among Central Africans with human immunodeficiency virus (HIV) disease. Methods: This study had a cross-sectional design and was a prospective analysis of 102 patients with HIV disease (49 on ART versus 53 not on ART) in Kinshasa, Democratic Republic of Congo, between 2004 and 2008. A Cox regression model was used to assess for any relationship between type 2 diabetes and exposure to combination ART without protease inhibitors, after adjusting for known risk factors for type 2 diabetes, nadir CD4 and CD8 levels, viral load, marital status, and religion. Results: Unexpectedly elevated rates of smoking, excess alcohol intake, and ART-related total, abdominal, and peripheral obesity were observed in our study group of HIV patients. At the end of follow-up, five patients were diagnosed with type 2 diabetes (incidence rate 4.9%, 9.8 per 1000 person-years). Univariate risk factors for type 2 diabetes were male gender (relative risk [RR] 1.1, 95% confidence interval [CI] 1.01–1.4; P = 0.019), traditional religion versus new charismatic religion (RR 1.1, 95% CI 1.01–1.3; P = 0.046), exposure to ART (RR 1.1, 95% CI 1.002–1.3; P = 0.034), and single status (RR 6.2, 95% CI 1.5–15; P = 0.047). In multivariate analysis, strong significant independent predictors of type 2 diabetes were belonging to a traditional religion (HR 2.1, 95% CI 1.1–4.2; P = 0.036) and a relative increase in nadir CD4 cell count (beta coefficient 0.003; P < 0.0001). Conclusion: ART-related obesity and type 2 diabetes are becoming increasing problems in Central Africans with HIV disease. A relative increase in nadir CD4 count and traditional religion status appear to be the strongest independent predictors of type 2 diabetes.

Mandina Ndona, Madone; Longo-Mbenza, Benjamin; Wumba, Roger; Tandu Umba, Barthelemy; Buassa-bu-Tsumbu, Baudouin; Mbula Mambimbi, Marcel; Wobin, Thaddee Odio; Mbungu Fuele, Simon

2012-01-01

142

A New Radiometric Calibration Paradigm for the OMPS Nadir Total Column and Profile Instruments  

NASA Technical Reports Server (NTRS)

A fused silica Mie Scattering Diffuser (MSD) has been developed at Ball Aerospace & Technology Corp. that has measured characteristics which could be used to increase the accuracy of the spectral albedo calibration of the Ozone Mapping and Profiler Suite (OMPS) Nadir ozone total column and profile instrument by almost an order of magnitude. Measurements have been made of the optical characteristics on both natural and synthetic forms of fused silica MSDs. Preliminary measurements suggest that MSDs are useable in the solar reflective wavelength region from 250 nm to 3.7 m. To date synthetic and natural MSDs have been irradiated for 60 hours of UV radiation from a solar simulator, and synthetic MSDs have been irradiated with increasing doses of Co-60 gamma rays at 30, 500 krads up to 1.5 Mrads, and 30 krads of 200 MeV protons. The principal effects have been small loses in transmittance at wavelengths < 350 nm. The high energy particle irradiation measurements were provided by Neal Nickles and Dean Spieth.

Heath, Donald; Georgiew, Georgi

2011-01-01

143

Peculiarities of backscattering in multifrequency nadir probing of the sea surface  

NASA Astrophysics Data System (ADS)

Backscattering of centimeter electromagnetic waves during nadir probing of the sea surface is considered in an approximation of the Kirchoff method and a two-scale model of the scattering surface. A model of the effective reflection coefficient is developed under the assumption of the specified roughness spectrum model, and the coefficients for Ku (0.021 m), C (0.055 m), and S (0.09 m) bands are calculated. The dependence of the backscattering cross section on the wind speed, wind fetch, and the height of the swell are numerically investigated. The proximity of the numerical estimates and the experimental data is demonstrated. The dependence of the difference of two cross sections on the wind speed or on one of the backscattering cross sections is analyzed in dual-frequency measurements. It is shown that the numerical model made it possible to describe the nonmonotonic behavior of the difference cross section for the Ku-C and Ku-S pairs for the first time. The developed effective reflection coefficient model made it possible to predict in the numerical experiment the behavior of the difference cross section of a new frequency pair (C and S) for which in situ measurements have not yet been performed.

Karaev, V. Yu.; Kanevsky, M. B.; Meshkov, E. M.

2012-12-01

144

Martian dust clouds : two Martian years of SPICAM UV nadir measurements  

NASA Astrophysics Data System (ADS)

SPICAM instrument onboard Mars Express has been successfully operated for over two Martian years (MY 27 and MY 28). UV measurements (200-310 nm) in the nadir mode allowed to register presence of mineral dust and to build spatio-temporal dust distribution maps. The absorbing properties of the Martian dust in the UV permitted easily to separate the observed ice and dust clouds. The following dust optical parameters were used in this paper: single scattering albedo w=0.64 ± 0.04 and asymmetry factor g = 0.86 ± 0.03 at 300 nm and w=0.6 ± 0.045 g,=0.88 ± 0.04 at 213 nm [1]. The cold northern spring and summer exhibit relatively low dust loading with dust optical thickness ? =0.1-0.5 while the warmer end of southern spring and southern summer is the season of dust storms. The measurements cover two Martian southern summers. At this time the background dust loading increased up to ? =1-1.5. The regional dust storms with much higher intensity were also registered: the October 2005 dust storm with the maximal dust optical thickness ? about 3 and the July 2007 dust storm with ? up to 5. The obtained values of the dust optical thickness show good agreement with the values measured by the two Martian rovers, Spirit and Opportunity. [1]Mateshvili, N. et al. (2007), Adv. Space Res., 40, DOI:10.1016/j.asr.2007.06.028;

Mateshvili, Nina; Mateshvili, Nina; Fussen, Didier; Vanhellemont, Filip; Bingen, Christine; Stapelle, Maxime; Dodion, Jan; Dekemper, Emmanuel; Loodts, Nicolas

145

Water ice clouds in the Martian atmosphere: Two Martian years of SPICAM nadir UV measurements  

NASA Astrophysics Data System (ADS)

The SPICAM instrument onboard Mars Express has successfully performed two Martian years (MY 27 and MY28) of observations. Water ice cloud optical depths spatial and temporal distribution was retrieved from nadir measurements in the wavelength range 300-320 nm. During the northern spring the cloud hazes complex distribution was monitored. The clouds in the southern hemisphere formed a zonal belt in the latitude range 30-60°S. The edge of the retreating north polar hood merged with the northern tropical clouds in the range 250-350°E. The development of the aphelion cloud belt (ACB) started with the weak hazes formation (cloud optical thickness 0.1-0.3) in the equatorial region. At the end of the northern spring, the ACB cloud optical thickness reached already values of 0.3-1. The ACB decay in the end of the northern summer was accompanied with a presence of clouds in the north mid-latitudes. The expanded north polar hood merged with the north mid-latitude clouds in the eastern hemisphere. The interannual comparison indicates a decrease in cloud activity immediately after a strong dust storm in southern summer of MY28. The strong dust storms of the MY28 may also be a reason of the observed north polar hood edge shifting northward by 5°.

Mateshvili, N.; Fussen, D.; Vanhellemont, F.; Bingen, C.; Dekemper, E.; Loodts, N.; Tetard, C.

2009-07-01

146

MISR stereoscopic image matchers: techniques and results  

Microsoft Academic Search

The Multi-angle Imaging SpectroRadiometer (MISR) instrument, launched in December 1999 on the NASA EOS Terra satellite, produces images in the red band at 275-m resolution, over a swath width of 360 km, for the nine camera angles 70.5°, 60°, 45.6°, and 26.1° forward, nadir, and 26.1°, 45.6°, 60°, and 70.5° aft. A set of accurate and fast algorithms was developed

Jan-Peter Muller; Athula Mandanayake; Catherine Moroney; Roger Davies; David J. Diner; Susan Paradise

2002-01-01

147

The feasibility of retrieving vertical temperature profiles from satellite nadir UV observations: A sensitivity analysis and an inversion experiment with neural network algorithms  

NASA Astrophysics Data System (ADS)

Atmospheric temperature profiles are inferred from passive satellite instruments, using thermal infrared or microwave observations. Here we investigate on the feasibility of the retrieval of height resolved temperature information in the ultraviolet spectral region. The temperature dependence of the absorption cross sections of ozone in the Huggins band, in particular in the interval 320-325 nm, is exploited. We carried out a sensitivity analysis and demonstrated that a non-negligible information on the temperature profile can be extracted from this small band. Starting from these results, we developed a neural network inversion algorithm, trained and tested with simulated nadir EnviSat-SCIAMACHY ultraviolet observations. The algorithm is able to retrieve the temperature profile with root mean square errors and biases comparable to existing retrieval schemes that use thermal infrared or microwave observations. This demonstrates, for the first time, the feasibility of temperature profiles retrieval from space-borne instruments operating in the ultraviolet.

Sellitto, P.; Del Frate, F.

2014-07-01

148

Evaluation of the Sensor Data Record from the nadir instruments of the Ozone Mapping Profiler Suite (OMPS)  

NASA Astrophysics Data System (ADS)

paper evaluates the first 15 months of the Ozone Mapping and Profiler Suite (OMPS) Sensor Data Record (SDR) acquired by the nadir sensors and processed by the National Oceanic and Atmospheric Administration Interface Data Processing Segment. The evaluation consists of an inter-comparison with a similar satellite instrument, an analysis using a radiative transfer model, and an assessment of product stability. This is in addition to the evaluation of sensor calibration and the Environment Data Record product that are also reported in this Special Issue. All these are parts of synergetic effort to provide comprehensive assessment at every level of the products to ensure its quality. It is found that the OMPS nadir SDR quality is satisfactory for the current Provisional maturity. Methods used in the evaluation are being further refined, developed, and expanded, in collaboration with international community through the Global Space-based Inter-Calibration System, to support the upcoming long-term monitoring.

Wu, Xiangqian; Liu, Quanhua; Zeng, Jian; Grotenhuis, Michael; Qian, Haifeng; Caponi, Maria; Flynn, Larry; Jaross, Glen; Sen, Bhaswar; Buss, Richard H.; Johnsen, William; Janz, Scott; Pan, Chunhui; Niu, Jianguo; Beck, Trevor; Beach, Eric; Yu, Wei; Rama Varma Raja, M. K.; Stuhmer, Derek; Cumpton, Daniel; Owen, Cristina; Li, Wen-Hao

2014-05-01

149

Low earth orbiting Nadir Etalon Sounding Spectrometer instrument concept for temperature, moisture and trace species, LeoNESS  

NASA Technical Reports Server (NTRS)

A concept for a low earth orbiting nadir etalon spectrometer sounder (LeoNESS) is described which can achieve retrieval of temperature, H2O, surface, boundary conditions, cloudiness, and trace species with an accuracy that meets or exceeds the AIRS specifications. Options employing 65-K and 30-K detectors are examined; the former may be implemented via passive radiative cooling. The concept, which is derived from the Cryogenic Limb Array Etalon Spectrometer, has the potential for improving the horizontal and vertical resolution.

Kumer, J. B.; Sterritt, L. W.; Roche, A. E.; Rosenberg, W. J.; Morrow, H. E.; Shenk, W. E.; Susskind, J.

1992-01-01

150

Crustal structure of a young margin pair: New results across the Liguro-Provencal Basin from wide-angle seismic tomography  

NASA Astrophysics Data System (ADS)

Tomographic inversion of two wide-angle seismic profiles acquired during the Sardinia cruise (2006) on the conjugate Gulf of Lions-West Sardinia margins pair offers insight into the deep structure of this young basin. It is the first combined conjugate margins study in this area based on deep seismic data. Modelling of the two conjugate profiles reveals that the conjugate margins are symmetric in term of crustal velocity structure, with a partitioning in three similar regions: (1) a zone of low crustal vertical velocity gradients and a crustal thickness of 18 to 10 km, interpreted to be thinned continental crust, (2) a transitional zone characterised by high lower crustal velocities, non-typical of continental or normal oceanic crust, and (3) a 4- to 5-km-thick crust showing vertical velocity gradients and relative velocity ranges typical of oceanic crust. This latter region is interpreted to be a thin oceanic crust resulting from a tectonic heritage and the possible influence of a cool slab back-arc basin. Although the three regions are found on both sides of the margin, they are asymmetric in terms of the width of these domains, wide and smooth along the Gulf of Lions margin, and narrow and abrupt along its conjugate Sardinia side. The width of Region 2 is larger on the Gulf of Lions side (~ 90 km) than on the Sardinia side (~ 40 km). Crustal thickness in Region 3 is about 1 km thinner on the Sardinia side than on its conjugate. In Region 1 the crustal thickness is lower on the Sardinia side at a given distance from the shelf break. The differences in width of Region 2 and in crustal thickness might be due to the origin as a back-arc basin of the NW-Mediterranean basin, with the final breakup located closer to the Western Sardinia margin, also probably linked to the complex tectonic history of the region. Our results do not support a simple shear mechanism of the opening of the basin along a lithospheric detachment fault.

Gailler, A.; Klingelhoefer, F.; Olivet, J.-L.; Aslanian, D.; Sardinia scientific party; Technical OBS Team

151

Directional anisotropy in thermal infrared measurements over Toulouse city centre during the CAPITOUL measurement campaigns: first results  

NASA Astrophysics Data System (ADS)

The measurements of surface temperature are prone to important directional anisotropy related to the structure of the canopy and the radiative and energy exchanges inside of it. Directional effects must be taken into account for a number of practical applications such as the correction of large swath satellite data, the assimilation of thermal infrared (TIR) measurements in surface models, the design of future spatial missions… For urban canopies, experimental measurements of TIR directional anisotropy previously performed during summer days over Marseille in the framework of the ESCOMPTE campaign (2001) revealed significant angular surface temperature variations with noticeable hot spot effects whose intensity was related to the canopy structure. The CAPITOUL project ( http://medias.cnrs.fr/capitoul/ ) provided the opportunity to extend these results to other seasons and to nighttime conditions. The experimental setup is based on the use of 2 airborne TIR cameras with different lenses, inclination and resolution, and installed aboard a small aircraft. The flight protocol allowed the retrieval of directional anisotropy in all azimutal directions and in a range of zenith viewing angles between nadir and 62°. Measurements were performed during several intensive operation periods (IOP) in summer (2004 july), autumn (2004 September and October) and winter (2005 February). Only the first results of the 2004 autumn and 2005 winter IOPs are presented in this paper. The results obtained in daytime conditions confirm the systematic hot spot effects observed in previous experiments over cities. The variations found seem to be particularly important in winter when sun elevation is low: for instance they range between -4 and 10 K between oblique and nadir viewing in February. During nighttime conditions, angular variations are much lower (always less than 2 K between nadir and 60° zenithal viewing angle), whichever the azimutal viewing direction.

Lagouarde, J.-P.; Irvine, M.

2008-12-01

152

Results from 1984 airborne Doppler lidar wind measurement program. Flight 6: Analysis of line-of-sight elevation angle errors and apparent Doppler velocities  

NASA Technical Reports Server (NTRS)

During the summer of 1984 the Marshall Space Flight Center's Airborne Doppler Lidar System (ADLS) made a series of wind measurements in the California Central Valley. This study quantifies the lidar beam angle errors and velocity errors through analysis of ground return signals. Line-of-sight elevation (LOSE) angle errors are under 1 deg. Apparent Doppler ground velocities, as large as 2m/s, are considerably less than in a previous flight experiment in 1981. No evidence was found of a Schuler resonance phenomenon common to inertial navigation systems (INS), however the aperiodic nature of the apparent velocities implies an error in the INS-derived ground speeds. Certain features and subtleties in the ground returns are explained in terms of atmospheric structure and characteristics of the ADLS hardware and software. Finally, least squares and low-pass filtering techniques are suggested for eliminating errors during post-processing.

Rothermel, Jeffry

1987-01-01

153

What's the Angle?  

NSDL National Science Digital Library

This classroom activity helps students understand how the angle of the Sun affects temperatures around the globe. After experimenting with a heat lamp and thermometers at differing angles, students apply what they learned to explain temperature variations on Earth. The printable six-page handout includes a series of inquiry-based questions to get students thinking about what they already know about temperature patterns, detailed experiment directions and a worksheet that helps students use the experiment results to gain a deeper understanding of seasonal temperature changes and why Antarctica is always so cold.

154

What Is the Angle?  

NSDL National Science Digital Library

This activity will help students understand how the angle of the Sun affects temperatures around the globe. After experimenting with a heat lamp and thermometers at differing angles, students apply what they learned to explain temperature variations on Earth. The printable six-page handout includes a series of inquiry-based questions to get students thinking about what they already know about temperature patterns, detailed experiment directions, and a worksheet that will help students use the experiment results to gain a deeper understanding of seasonal temperature changes and why Antarctica is always so cold. The students will explore all the angles of sunlight with a few thermometers and a heat lamp and understand why there is such a dramatic temperature change between the equator and the South Pole.

155

Mesospheric Clouds on Mars in Nadir-Pointed THEMIS-VIS Images  

Microsoft Academic Search

We present images of very-high-altitude clouds obtained at near-zero emission angles by the Mars Odyssey spacecraft's Thermal Emission Spectrometer visible subsystem (THEMIS-VIS). Although THEMIS-VIS was not designed or intended for stereo imaging, the parallax effect caused by its multiple exposure color-imaging sequence allows the height of clouds with sufficient spatial contrast to be determined with a precision of 5-10 km.

T. H. McConnochie; J. F. Bell; D. Savransky; M. J. Wolff; P. R. Christensen

2004-01-01

156

The topographic effect on spectral response from nadir-pointing sensors  

NASA Technical Reports Server (NTRS)

It is difficult to interpret multispectral Landsat earth resources data in areas of rugged and mountainous terrain because of the topographic effect on the sensor response. The objectives of this study were to examine and quantify the topographic effect on the sensor response from a uniform sand surface, to assess a simple theoretical incidence model for modeling the radiance from the surface, and to simulate Landsat sensor response due to the topographic effect. A field experiment was designed to collect data from a large range of slope angles and aspects at a range of solar elevations, using a hand-held radiometer. Analysis of these data showed that the magnitude of the topographic effect varied as a function of the solar elevation, the azimuthal orientation of the slope, and the slope inclination. The field measured variations in spectral response were found to have generally strong correlations with the theoretical model, and it was shown that the applicability of the Lambertian assumption varied within and between data sets. It is concluded that if slope angle, aspect, and solar zenith angle and azimuth are known, a technique incorporating a model to reduce the topographic effect prior to multispectral classification may be developed.

Holben, B. N.; Justice, C. O.

1980-01-01

157

VHF Radar Measurements of Tropical Forests in Panama: Results from the BioSAR Deployment in Central America  

NASA Technical Reports Server (NTRS)

A synthetic aperture radar sensor operating in 5 bands between 80 and 120 MHz was flown over forested areas in the canal zone of the Republic of Panama in an experiment to measure biomass in heavy tropical forests. The sensor is a pulse coherent SAR flown on a small aircraft and oriented straight down. The doppler history is processed to collect data on the ground in rectangular cells of varying size over a range of incidence angles fore and aft of nadir (+45 to - 45 degrees). Sensor data consists of 5 frequency bands with 20 incidence angles per band. Sensor data for over 12+ sites were collected with forest stands having biomass densities ranging from 50 to 300 tons/ha dry above ground biomass. Results are shown exploring the biomass saturation thresholds using these frequencies, the system design is explained, and preliminary attempts at data visualization using this unique sensor design are described.

Imhoff, Marc; Lawrence, William; Condit, Richard; Wright, Joseph; Johnson, Patrick; Holford, Warren; Hyer, Joseph; May, Lisa; Carson, Steven

2000-01-01

158

The Feasibility of Tropospheric and Total Ozone Determination Using a Fabry-perot Interferometer as a Satellite-based Nadir-viewing Atmospheric Sensor. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

Monitoring of the global distribution of tropospheric ozone (O3) is desirable for enhanced scientific understanding as well as to potentially lessen the ill-health impacts associated with exposure to elevated concentrations in the lower atmosphere. Such a capability can be achieved using a satellite-based device making high spectral resolution measurements with high signal-to-noise ratios; this would enable observation in the pressure-broadened wings of strong O3 lines while minimizing the impact of undesirable signal contributions associated with, for example, the terrestrial surface, interfering species, and clouds. The Fabry-Perot Interferometer (FPI) provides high spectral resolution and high throughput capabilities that are essential for this measurement task. Through proper selection of channel spectral regions, the FPI optimized for tropospheric O3 measurements can simultaneously observe a stratospheric component and thus the total O3 column abundance. Decreasing stratospheric O3 concentrations may lead to an increase in biologically harmful solar ultraviolet radiation reaching the earth's surface, which is detrimental to health. In this research, a conceptual instrument design to achieve the desired measurement has been formulated. This involves a double-etalon fixed-gap series configuration FPI along with an ultra-narrow bandpass filter to achieve single-order operation with an overall spectral resolution of approximately .068 cm(exp -1). A spectral region of about 1 cm(exp -1) wide centered at 1054.73 cm(exp -1) within the strong 9.6 micron ozone infrared band is sampled with 24 spectral channels. Other design characteristics include operation from a nadir-viewing satellite configuration utilizing a 9 inch (diameter) telescope and achieving horizontal spatial resolution with a 50 km nadir footprint. A retrieval technique has been implemented and is demonstrated for a tropical atmosphere possessing enhanced tropospheric ozone amounts. An error analysis assessing the impact on retrieved O3 amounts of the most significant uncertainties associated with this particular measurement has been performed for several different types of atmospheres. Results show the proposed instrumentation to enable a good measurement of absolute ozone amounts and an even better determination of relative changes, with a range of accuracy to within 7.55 to 20.6 percent for integrated tropospheric amounts (and 1.99 to 4.02 percent for total O3 column abundance) and a corresponding range in precision to within 7.73 to 10.4 percent (and 3.30 to 3.95 percent for total O3 column abundance), for the atmospheric conditions considered.

Larar, Allen Maurice

1993-01-01

159

Seismic structure of the main geological provinces off the SW Iberian margin: first results from the NEAREST-SEIS wide-angle seismic survey  

NASA Astrophysics Data System (ADS)

The region offshore the SW Iberian margin hosts the present-day NW-SE plate convergence between the European and African Plates at a rate of 4.5 mm/yr, fact that causes continuous seismic activity of moderate magnitude. In autumn 2008 a Spanish-French team carried out a refraction and wide-angle reflection seismic survey in the area (NEAREST-SEIS cruise), in the framework of the EU, FP6-funded NEAREST project. During the survey two long seismic profiles were acquired using a pool of 36 Ocean Bottom Seismometers (OBS), with the objectives of providing information about the geometry of the crust-mantle boundary and the physical properties of the crust, revealing the deep geometry of the main fault interfaces, and identifying the nature of the basement and the limits of the different geological provinces in the region. A total of 30 OBS were deployed along profile P1, which is 356 km long and trends NW-SE from the Tagus abyssal plain (TAP), crossing the Gorringe bank (GB), the Horseshoe abyssal plain (HAP) and the Coral Patch Ridge (CPR), up to the thrust-and-fold belt of the Seine abyssal plain (SAP). The acquired data were modeled by joint refraction and reflection travel time inversion, following a layer-stripping strategy. The inverted model show four well-differentiated domains in terms of its seismic structure: In the TAP a 3-4 km-thick, low velocity sedimentary layer covers the basement, which shows a remarkably high velocity (>7 km/s), similar to that of the basement outcropping in the Gorringe bank. In the HAP the sedimentary cover is thicker, showing an upper unit with low velocity corresponding to the Horseshoe gravitational unit, on top of a higher velocity lower unit, which may represent the highly consolidated Mesozoic sedimentary sequence. The thickness of the two units together exceeds 5 km. The basement shows the same velocity distribution as in TAP and GB, suggesting a common nature and origin. According to its seismic structure, and considering that there is no evidence for the presence of a basal reflector (e.g. Moho) in the record sections, we interpret this basement as highly serpentinized, exhumed mantle. In contrast, the CPR and SAP show evidences for the presence of a well-developed, 6-7 km-thick oceanic crust, underlying the 2-3 km-thick, moderate velocity, Mesozoic sedimentary sequence. Profile P2 is 256 km long, and trends S-N from the easternmost SAP beyond the NW Moroccan margin, crossing the Gulf of Cadiz imbricated wedge and the Portimao bank ending at the Iberian margin shelf. 15 OBS and 7 land-stations were deployed along this profile, and the recorded data were modeled following the same approach and strategy as for P1. The inverted model shows two main domains: In the southern half, there is a 3-4 km-thick cover of low velocity sediments, which represents the western edge of the sedimentary wedge that covers the internal Gulf of Cadiz, overlying a 7-8 km-thick oceanic crust. According to recent tectonic reconstructions, this crustal segment should have been emplaced there during the early phase of continental spreading between Iberia and Africa, in the context of Mesozoic Atlantic spreading. The northern part of P2 displays a relatively sharp ocean-continent transition zone concentrated in a ~50 km-wide band, that ends with the ~30 km-thick continental crust of the SW Iberian shelf.

Sallarès, Valentí; Martínez-Loriente, Sara; Gailler, Audrey; Bartolomé, Rafael; Gutscher, Marc-André; Graindorge, David; Lia Grácia, Eulà; Díaz, Jordi

2010-05-01

160

Seismic structure and crustal nature of the geological provinces off the SW Iberian margin: results of the NEAREST-SEIS wide-angle seismic survey  

NASA Astrophysics Data System (ADS)

The region offshore the SW Iberian margin hosts the present-day NW-SE plate convergence between the European and African Plates causing continuous seismic activity of moderate magnitude. In autumn 2008 a Spanish-French team carried out a wide-angle seismic survey in the area (NEAREST-SEIS cruise), in the framework of the EU-funded NEAREST project. During the survey two long profiles were acquired using a pool of 36 Ocean Bottom Seismometers (OBS), to provide information about the crustal structure and nature of the different geological provinces, and to reveal the deep geometry of the main fault interfaces. A total of 30 OBS were deployed along profile P1, which is 356 km long and trends NW-SE from the Tagus abyssal plain (TAP), crossing the Gorringe bank (GB), the Horseshoe abyssal plain (HAP) and the Coral Patch Ridge (CPR), up to the thrust-and-fold belt of the Seine abyssal plain (SAP). The inverted model along this profile show four different domains. In the TAP a 3-4 km-thick, low velocity sedimentary layer covers the basement, which shows a velocity >7 km/s just 2-3 km below its top, similarly to that of the basement outcropping in the Gorringe bank. In the HAP the sedimentary cover is thicker, showing an upper unit with low velocity corresponding to the Horseshoe gravitational unit, on top of a higher velocity lower unit, which may represent the highly consolidated Mesozoic sedimentary sequence, with a total thickness of 5 km. The basement shows the same velocity distribution as in TAP and GB, suggesting a common nature and origin. According to its seismic structure, we interpret this basement as highly serpentinized, exhumed mantle. In contrast, the CPR and SAP show evidences for the presence of a well-developed, 6-7 km-thick oceanic crust, underlying the sedimentary sequence. Profile P2 is 256 km long, and trends S-N from the easternmost SAP beyond the NW Moroccan margin, crossing the Gulf of Cadiz imbricated wedge and the Portimao bank ending at the Iberian margin shelf. 15 OBS and 7 land-stations were deployed along this profile. The inverted model shows two main domains: In the southern half, there is a 3-4 km-thick cover of low velocity sediments, which represents the western edge of the wedge that covers the internal Gulf of Cadiz, overlying a 7-8 km-thick oceanic crust. According to recent tectonic reconstructions, this crustal segment should have been emplaced there during the early phase of continental spreading between Iberia and Africa, in the context of Mesozoic Atlantic spreading. The northern part of P2 displays a relatively sharp ocean-continent transition zone concentrated in a ˜50 km-wide band, that ends with the ˜30 km-thick continental crust of the SW Iberian shelf.

Sallares, V.; Martinez, S.; Gailler, A.; Gutscher, M.; Bartolome, R.; Gracia, E.; Diaz, J.

2010-12-01

161

MISR Multi-angle Views of Sunday Morning Fires  

NASA Technical Reports Server (NTRS)

Hot, dry Santa Ana winds began blowing through the Los Angeles and San Diego areas on Sunday October 21, 2007. Wind speeds ranging from 30 to 50 mph were measured in the area, with extremely low relative humidities. These winds, coupled with exceptionally dry conditions due to lack of rainfall resulted in a number of fires in the Los Angeles and San Diego areas, causing the evacuation of more than 250,000 people.

These two images show the Southern California coast from Los Angeles to San Diego from two of the nine cameras on the Multi-angle Imaging SpectroRadiometer (MISR) instrument on the NASA EOS Terra satellite. These images were obtained around 11:35 a.m. PDT on Sunday morning, October 21, 2007 and show a number of plumes extending out over the Pacific ocean. In addition, locations identified as potential hot spots from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the same satellite are outlined in red.

The left image is from MISR's nadir looking camera and the plumes appear very faint. The image on the right is from MISR's 60o forward looking camera, which accentuates the amount of light scattered by aerosols in the atmosphere, including smoke and dust. Both these images are false color and contain information from MISR's red, green, blue and near-infrared wavelengths, which makes vegetated land appear greener than it would naturally. Notice in the right hand image that the color of the plumes associated with the MODIS hot spots is bluish, while plumes not associated with hot spots appear more yellow. This is because the latter plumes are composed of dust kicked up by the strong Santa Ana winds. In some locations along Interstate 5 on this date, visibility was severely reduced due to blowing dust. MISR's multiangle and multispectral capability give it the ability to distinguish smoke from dust in this situation.

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. These images were generated from a portion of the imagery acquired during Terra orbit 41713, and use data from blocks 63 to 66 within World Reference System-2 path 40.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science Data Center. JPL is a division of the California Institute of Technology.

2007-01-01

162

Effects of skylight polarization, cloudiness, and view angle on the detection of oil on water.  

NASA Technical Reports Server (NTRS)

Three passive radiometric techniques, which use the contrast of sunlight reflected and backscattered from oil and water in specific wavelength regions, have potential application for remote sensing of oil spills. These techniques consist of measuring (1) total radiance, (2) the polarization components (normal and parallel) of radiance, and (3) the difference between the normal and parallel components. In this paper, the best view directions for these techniques are evaluated, conclusions are drawn as to the most promising technique, and explanations are developed to describe why previous total-radiance measurements yielded highest contrast between oil and water under overcast skies. The technique based on measurement of only the normal polorization component appears to be the most promising. The differential technique should be further investigated because of its potential to reduce the component of backscattered light from below the surface of the water. Measurements should be made about 45 deg nadir view angle in the direction opposite the sun. Overcast sky conditions provide a higher intensity of skylight relative to clear sky conditions and a lower intensity of backscatter within the water relative to surface reflectance. These factors result in higher contrast between oil and water under overcast skies.

Millard, J. P.; Arvesen, J. C.

1971-01-01

163

Angles and Area  

NSDL National Science Digital Library

In this activity (page 10 of PDF), learners approximate the area of the uppermost cross section of an impact crater using a variety of square grids. They conclude which angle of impact results in the greatest area. There are two versions of this activity: Challenge, where students construct a launcher and create their own craters; and Non-Challenge where students analyze pictures of craters. Includes a pre-lesson activity (p54). The Moon Math: Craters! guide follows a 5E approach, applying concepts of geometry, modeling, data analysis to the NASA lunar spacecraft mission, LCROSS.

Nasa

2012-05-08

164

Laser angle measurement system  

NASA Technical Reports Server (NTRS)

The design and fabrication of a laser angle measurement system is described. The instrument is a fringe counting interferometer that monitors the pitch attitude of a model in a wind tunnel. A laser source and detector are mounted above the mode. Interference fringes are generated by a small passive element on the model. The fringe count is accumulated and displayed by a processor in the wind tunnel control room. Optical and electrical schematics, system maintenance and operation procedures are included, and the results of a demonstration test are given.

Pond, C. R.; Texeira, P. D.; Wilbert, R. E.

1980-01-01

165

Mesospheric Clouds on Mars in Nadir-Pointed THEMIS-VIS Images  

NASA Astrophysics Data System (ADS)

We present images of very-high-altitude clouds obtained at near-zero emission angles by the Mars Odyssey spacecraft's Thermal Emission Spectrometer visible subsystem (THEMIS-VIS). Although THEMIS-VIS was not designed or intended for stereo imaging, the parallax effect caused by its multiple exposure color-imaging sequence allows the height of clouds with sufficient spatial contrast to be determined with a precision of 5-10 km. To determine cloud height in a given image, we make an initial guess of the height, reproject the subframes that make up the image onto a surface of that elevation, and then examine the reprojected imagine to determine whether the cloud features are properly aligned in overlapping subframes. This process is repeated until the best fitting elevation is found. The precision of the height estimate obtained in this manner is obviously limited by the sharpness of the cloud features. Although clouds and hazes are common in the THEMIS-VIS data set, images in which a cloud height can be measured are extremely rare. To date, we have only two detections of equatorial high-altitude clouds, both of which occur (possibly coincidentally) over high surface elevations in the eastern Tharsis bulge, but in quite different seasons --- {L} {s} 26o and {L} {s} 114o. In both cases, the detections are in late-afternoon images, near 4:30 PM local solar time, the cloud heights are near 75 km above the local surface, and the cloud structure is wispy and lineated. Our detections are consistent with limb observations by TES (solar band) and MOC (Wide Angle) of high altitude clouds (Clancy et al., 2004, DPS). Clancy et al.~find that these clouds appear to be present only within a very restricted range of longitudes and seasonal intervals. In addition to the equatorial cloud measurements, we have also in a few instances been able to measure heights of 60-70 km for mid-latitude clouds near the fringes of the polar hood in early northern winter. This measurement requires the serendipitous confluence of unusually distinct cloud features and favorable lighting conditions, and so, at this time, it is difficult to assess the prevalence or nature of high altitude clouds in this region and season.

McConnochie, T. H.; Bell, J. F.; Savransky, D.; Wolff, M. J.; Christensen, P. R.

2004-12-01

166

Describe Angle Pair Relationships  

NSDL National Science Digital Library

This lesson will explain the types of pairs of angles you will find in Geometry. Note taking time on page 5: Angle Information Now, let's see if you get it: Angle Relationship Quiz (fun) Ok! Now for your assignment, #8 on page 38! Class Zone Geometry Textbook ...

Neubert, Mrs.

2011-09-01

167

What's Your Angle?  

NSDL National Science Digital Library

In this activity, students devise procedures for using a protractor to measure the number of degrees in an angle, and use inductive reasoning to develop "angle sense." Then they describe circumstances and careers that require a working knowledge of angles and their measurements.

2010-01-01

168

PSA Nadir Is a Significant Predictor of Treatment Failure after High-Intensity Focussed Ultrasound (HIFU) Treatment of Localised Prostate Cancer  

Microsoft Academic Search

ObjectivesTo assess if prostate-specific antigen (PSA) nadir is an independent predictor of treatment failure and disease-free survival after high-intensity focussed ultrasound (HIFU) therapy for localised prostate cancer as defined by the new ASTRO criteria.

Roman Ganzer; Sebastian Rogenhofer; Bernhard Walter; Jens-Claudio Lunz; Martin Schostak; Wolf F. Wieland; Andreas Blana

2008-01-01

169

Tropospheric Ozone Column Retrieval From ESA-Envisat SCIAMACHY Nadir UV\\/VIS Radiance Measurements by Means of a Neural Network Algorithm  

Microsoft Academic Search

Spaceborne measurements may significantly support monitoring the concentration of atmospheric constituents affecting air quality, such as ozone. However, retrieving tropospheric ozone concentration information from nadir satellite data is an arduous task, given the weak sensitivity of the earth's radiance to ozone variations in the lower part of the atmosphere. We propose a new methodology, based on neural networks (NN), for

Pasquale Sellitto; Fabio Del Frate; Domenico Solimini; Stefano Casadio

2012-01-01

170

Nadir CD4 count and monthly income predict cervical squamous cell abnormalities in HIV-positive women in a resource-limited setting.  

PubMed

We conducted a cross-sectional study with 385 HIV-positive women in Bangkok to assess the prevalence and predictors of cervical abnormalities on Papanicolaou (Pap) smear. Low-grade squamous intraepithelial lesions (LSIL), high-grade SIL (HSIL) and invasive cervical cell cancer (ICC) were assessed by cytological examination after Pap smear and logistic regression models were used to assess associations with patient characteristics. Overall prevalence of LSIL, HSIL and ICC were 11.2% (95% confidence interval [CI] 8.2-14.7%), 4.7% (95%CI 2.8-7.3%) and 0.5% (95%CI 0.06-1.9%), respectively. In multivariate models, only the nadir CD4 count and income remained significantly associated with cytological abnormalities, whereas smoking, hormonal contraceptive or antiretroviral use, condom use, parity and number of lifetime sexual partners were not associated. The odds ratio for having cytological abnormalities was 2.6 (95% CI 1.24-5.34) in those with a nadir CD4 count <200 cells/mm3 compared with those with a higher nadir CD4 count, and 1.99 (1.11-3.57) in those with an income of <125 US dollars/month compared with those with higher incomes. In settings where access to affordable treatment is improving, this study reinforces the importance of regular Pap smear screening in HIV-positive women, particularly those with low nadir CD4 counts and lower incomes. PMID:18663038

Mangclaviraj, Somsamorn; Kerr, Stephen J; Chaithongwongwatthana, Surasith; Ananworanich, Jintanat; Hirschel, Bernard; Emery, Sean; Cooper, David A; Chotnopparatpattara, Pichai; Ruxrungtham, Kiat; Phanuphak, Praphan

2008-08-01

171

Results.  

ERIC Educational Resources Information Center

Describes the Collegiate Results Instrument (CRI), which measures a range of collegiate outcomes for alumni 6 years after graduation. The CRI was designed to target alumni from institutions across market segments and assess their values, abilities, work skills, occupations, and pursuit of lifelong learning. (EV)

Zemsky, Robert; Shaman, Susan; Shapiro, Daniel B.

2001-01-01

172

Rain Fallspeeds and Rates Derived from Airborne Nadir-Pointing Doppler Radar Measurements.  

National Technical Information Service (NTIS)

The use of vertical-incidence Doppler velocity in addition to radar reflectivity may yield information on drop size distribution and therefore result in better rainrate estimates. Doppler velocity can provide useful information on the raindrop size distri...

G. M. Heymsfield L. Tian B. Geerts

1999-01-01

173

A new stratospheric and tropospheric NO2 retrieval algorithm for nadir-viewing satellite instruments: applications to OMI  

NASA Astrophysics Data System (ADS)

We describe a new algorithm for the retrieval of nitrogen dioxide (NO2) vertical columns from nadir-viewing satellite instruments. This algorithm (SP2) is the basis for the Version 2.1 OMI NO2 Standard Product and features a novel method for separating the stratospheric and tropospheric columns. The approach estimates the stratospheric NO2 directly from satellite data without using stratospheric chemical transport models or assuming any global zonal wave pattern. Tropospheric NO2 columns are retrieved using air mass factors derived from high-resolution radiative transfer calculations and a monthly climatology of NO2 profile shapes. We also present details of how uncertainties in the retrieved columns are estimated. The sensitivity of the retrieval to assumptions made in the stratosphere-troposphere separation is discussed and shown to be small, in an absolute sense, for most regions. We compare daily and monthly mean global OMI NO2 retrievals using the SP2 algorithm with those of the original Version 1 Standard Product (SP1) and the Dutch DOMINO product. The SP2 retrievals yield significantly smaller summertime tropospheric columns than SP1 and are relatively free of modeling artifacts and negative tropospheric NO2 values. In a re-analysis of an INTEX-B validation study, we show that SP2 largely eliminates a ∼20% discrepancy that existed between OMI and independent in situ springtime NO2 SP1 measurements.

Bucsela, E. J.; Krotkov, N. A.; Celarier, E. A.; Lamsal, L. N.; Swartz, W. H.; Bhartia, P. K.; Boersma, K. F.; Veefkind, J. P.; Gleason, J. F.; Pickering, K. E.

2013-02-01

174

The Retroacetabular Angle Determines the Safe Angle for Screw Placement in Posterior Acetabular Fracture Fixation  

PubMed Central

Introduction. A method for the determination of safe angles for screws placed in the posterior acetabular wall based on preoperative computed tomography (CT) is described. It defines a retroacetabular angle and determines its variation in the population. Methods. The retroacetabular angle is the angle between the retroacetabular surface and the tangent to the posterior acetabular articular surface. Screws placed through the marginal posterior wall at an angle equal to the retroacetabular angle are extraarticular. Medial screws can be placed at larger angles whose difference from the retroacetabular angle is defined as the allowance angles. CT scans of all patients with acetabular fractures treated in our institute between September 2002 to July 2007 were used to measure the retroacetabular angle and tangent. Results. Two hundred thirty one patients were included. The average (range) age was 42 (15–74) years. The average (range) retroacetabular angle was 39 (30–47) degrees. The average (range) retroacetabular tangent was 36 (30–45)?mm. Conclusions. Placing the screws at an average (range) angle of 39 (33–47) degrees of anterior inclination with the retroacetabular surface makes them extraarticular. Angles for medial screws are larger. Safe angles can be calculated preoperatively with a computer program.

Tadros, Ayman M. A.; Oxland, Thomas R.; O'Brien, Peter

2013-01-01

175

Reading Angles in Maps  

ERIC Educational Resources Information Center

Preschool children can navigate by simple geometric maps of the environment, but the nature of the geometric relations they use in map reading remains unclear. Here, children were tested specifically on their sensitivity to angle. Forty-eight children (age 47:15-53:30 months) were presented with fragments of geometric maps, in which angle sections…

Izard, Véronique; O'Donnell, Evan; Spelke, Elizabeth S.

2014-01-01

176

What's My Angle?  

NSDL National Science Digital Library

This interactive module offers learners the opportunity to check their knowledge of angle measure and estimation, and the use of a protractor. There are ten activities that vary the tasks and the degree of precision. The site is designed for whiteboard demonstration as well, and it includes a tutorial on angle types and protractor use.

2011-01-01

177

Wide Angle Optical Systems.  

National Technical Information Service (NTIS)

A wide angle optical field flattening system for a multispectral scanner is described which provides a large field angles and high resolution at low f-numbers. The system utilizes a basic optical element in the form of a first flat surface of a reflecting...

F. Vicik

1979-01-01

178

Neural network cloud screening algorithm Part II: global synthetic cases using high resolution spectra in O2 and CO2 near infrared absorption bands in nadir and sun glint  

NASA Astrophysics Data System (ADS)

In Part I a set of two layer feed-forward neural networks, trained via back propagation of sensitivities, was applied to a synthetic set of radiances in micro-windows of the near-infrared to make predictions of cloud water (cw), cloud ice (ci), effective scattering heights of cloud water and ice, (pcw and pci, respectively) and the column water vapor (w). A threshold test, using 2 g/m-2 for cloud water and 10 g/m-2 for cloud ice, was applied to the retrieved values to distinguish clear from cloudy scenes. In that work the discussion was limited to the nadir viewing geometry, and was applied only to land surfaces, excluding desert and snow and ice fields. Part II describes the extension to a set of high resolution radiances, as might be measured by a grating spectrometer from space, in both nadir and sun glint viewing geometries. Furthermore, results are given for all land surface types as well as scenes over ocean. Prior to neural network training, a Principal Component Analysis (PCA) is applied to the high resolution spectra, which consist of three bands centered at 0.76?m (O2 A-band), 1.61?m (weak CO2 band) and 2.06?m (strong CO2 band), each with 1016 channels. Analysis shows that the five leading EOFs together capture 99.9% of the variance in each band, reducing the data size by more than two orders of magnitude. Application of the trained neural networks to an independent data set, generated using CloudSat and Calipso cloud and aerosol profiles, as well as carbon dioxide profiles from a chemical transport model, were used to quantify the skill in the retrieval. The results vary significantly with surface type, viewing mode and cloud properties. Accuracies range from 7% to 100% (typically close to 75%), with confidence levels almost always greater than 90%.

Taylor, Thomas E.; O'Brien, D. M.

2010-03-01

179

Special Angle Pairs Discovery Activity  

NSDL National Science Digital Library

This lesson uses a discovery approach to identify the special angles formed when a set of parallel lines is cut by a transversal. During this lesson students identify the angle pair and the relationship between the angles. Students use this relationship and special angle pairs to make conjectures about which angle pairs are considered special angles.

Henry, Barbara

2012-04-16

180

Rain Fallspeeds and Rates Derived from Airborne Nadir-Pointing Doppler Radar Measurements  

NASA Technical Reports Server (NTRS)

The use of vertical-incidence Doppler velocity in addition to radar reflectivity may yield information on drop size distribution and therefore result in better rainrate estimates. Doppler velocity can provide useful information on the raindrop size distribution. Doppler velocities from a zenith-pointing radar represent the sum of the mean reflectivity-weighted hydrometeor fallspeed and the vertical air motion. Dual-parameter rain estimation methods using the Doppler velocity, require that the latter can be removed, or is negligible. Atlas et al. (1972) derived relations between Doppler velocity, reflectivity, and rain rate assuming an exponential size distribution for rain. Ulbrich (1994) expanded on this work by deriving the relation between the Doppler velocity and the reflectivity assuming a Gamma size distribution. This distribution provides a more realistic representation of the small rain drops. To get accurate information on raindrop size distributions with the above method, the air motions must be removed from the observed Doppler velocities

Heymsfield, Gerald M.; Tian, L.; Geerts, Bart

1999-01-01

181

Modeling the nadiral low-frequency pulse return of one-dimensionally rough surfaces  

NASA Astrophysics Data System (ADS)

Measurements of radar pulse return waveforms are known to provide information on properties of the observed surface, and are commonly used in oceanographic altimetry. In such applications, the convolution model (also called the ?Brown model?) is widely applied for waveform analysis. This model describes pulse return waveforms as a multiple convolution of the ?flat surface impulse response?, the surface's height probability density function, and the radar's point target response. The flat surface impulse response is typically determined by an integration of scattering contributions from incremental surface elements weighted by a geometrical optics (GO) prediction of the normalized radar cross-section of the elemental surfaces. Recent interest in the analysis of pulse return waveforms at VHF and lower frequencies for ice sheet sensing applications motivate reconsideration of the convolution model. While the ultimate goal of this effort is the development of a model to be utilized for interpreting VHF radar measurements over ice sheets, it is important first to establish the validity of the convolution model for these applications. Such an investigation, which involves the comparison of convolution model predictions with those of a method that does not require a separation of surface length-scales into ?elemental? and large-scale regions, is most easily performed for one-dimensional surfaces. This paper describes a derivation of the convolution model for one-dimensionally rough surfaces that is applicable at low frequencies, primarily through the replacement of GO surface scattering coefficients with those of a physical optics theory. The method is validated by comparing its predictions with a Monte Carlo physical optics approach. Results show the convolution model to provide reasonable estimates of the pulse return waveform, so that a similar method can be utilized to develop a convolution model for two-dimensional surface pulse return waveforms in ice-sheet sensing applications. The results also suggest the possibility of retrieving surface profile statistical information from waveform measurements.

Niamsuwan, N.; Johnson, J. T.; Jezek, K. C.

2011-01-01

182

Viewing angle changeable display  

NASA Astrophysics Data System (ADS)

Viewing angle changeable display can change the display viewing angle as needed: In the public place the display could have a narrow viewing angle for privacy, while in the private place the displays could have a wide viewing angle for the convenience of the operation and better viewing experience. This article propose a novel adjustable optical transmission device to realize the viewing angle changes for LCD by using the principle of guest- host effect of liquid crystal. The major technology is to insert a special equipment between the backlight and the LCD, through which the backlight will display either parallel or scattered features to get an either narrow or wide viewing angle. The equipment is an adjustable transmission cell (ATC) which is actually a black G-H LC cell. This ATC is the main focus of our invention. The ATC consists of a polarizer sheet and a special guest-host liquid crystal device filled with the two-phase dye (called as GH-LC in this report), to achieve the viewing angle change in the LCD. When an electrical field charges to the ATC, only the so-called near-axis lights can pass through the ATC within a relatively small angle, while the other scattered lights are absorbed sequentially by GH-LC and the polarizer sheet. On the other hand, when there is no electrical charge to the ATC, the cell behaves like a normal polarizer; and the scattered light can pass through the cell and polarizer in a normal way. This paper describes the principle and structure of the device, applies the electric field on the sample to observe the electro-optical properties, combine the theoretical and experimental research, getting the viewing angle effects of the display.

Leng, Jinbi; Huang, Ziqiang; Yang, Wenjun; Chen, Xiaoxi

2010-05-01

183

A new stratospheric and tropospheric NO2 retrieval algorithm for nadir-viewing satellite instruments: applications to OMI  

NASA Astrophysics Data System (ADS)

We describe a new algorithm for the retrieval of nitrogen dioxide (NO2) vertical columns from nadir-viewing satellite instruments. This algorithm (SP2) is the basis for the Version 2.1 OMI This algorithm (SP2) is the basis for the Version 2.1 Ozone Monitoring Instrument (OMI) NO2 Standard Product and features a novel method for separating the stratospheric and tropospheric columns. NO2 Standard Product and features a novel method for separating the stratospheric and tropospheric columns. The approach estimates the stratospheric NO2 directly from satellite data without using stratospheric chemical transport models or assuming any global zonal wave pattern. Tropospheric NO2 columns are retrieved using air mass factors derived from high-resolution radiative transfer calculations and a monthly climatology of NO2 profile shapes. We also present details of how uncertainties in the retrieved columns are estimated. The sensitivity of the retrieval to assumptions made in the stratosphere-troposphere separation is discussed and shown to be small, in an absolute sense, for most regions. We compare daily and monthly mean global OMI NO2 retrievals using the SP2 algorithm with those of the original Version 1 Standard Product (SP1) and the Dutch DOMINO product. The SP2 retrievals yield significantly smaller summertime tropospheric columns than SP1, particularly in polluted regions, and are more consistent with validation studies. SP2 retrievals are also relatively free of modeling artifacts and negative tropospheric NO2 values. In a reanalysis of an INTEX-B validation study, we show that SP2 largely eliminates an ~20% discrepancy that existed between OMI and independent in situ springtime NO2 SP1 measurements.

Bucsela, E. J.; Krotkov, N. A.; Celarier, E. A.; Lamsal, L. N.; Swartz, W. H.; Bhartia, P. K.; Boersma, K. F.; Veefkind, J. P.; Gleason, J. F.; Pickering, K. E.

2013-10-01

184

Meridional Distribution of CH3C2H and C4H2 in Saturn's Stratosphere from CIRS/Cassini Limb and Nadir Observations  

NASA Technical Reports Server (NTRS)

Limb and nadir spectra acquired by Cassini/CIRS (Composite InfraRed Spectrometer) are analyzed in order to derive, for the first time, the meridional variations of diacetylene (C4H2) and methylacetylene (CH3C2H) mixing ratios in Saturn's stratosphere, from 5 hPa up to 0.05 hPa and 80 deg S to 45 deg N. We find that the C4H2 and CH3C2H meridional distributions mimic that of acetylene (C2H2), exhibiting small-scale variations that are not present in photochemical model predictions. The most striking feature of the meridional distribution of both molecules is an asymmetry between mid-southern and mid-northern latitudes. The mid-southern latitudes are found depleted in hydrocarbons relative to their northern counterparts. In contrast, photochemical models predict similar abundances at north and south mid-latitudes. We favor a dynamical explanation for this asymmetry, with upwelling in the south and downwelling in the north, the latter coinciding with the region undergoing ring shadowing. The depletion in hydrocarbons at mid-southern latitudes could also result from chemical reactions with oxygen-bearing molecules. Poleward of 60 deg S, at 0.1 and 0.05 hPa, we find that the CH3C2H and C4H2 abundances increase dramatically. This behavior is in sharp contradiction with photochemical model predictions, which exhibit a strong decrease towards the south pole. Several processes could explain our observations, such as subsidence, a large vertical eddy diffusion coefficient at high altitudes, auroral chemistry that enhances CH3C2H and C4H2 production, or shielding from photolysis by aerosols or molecules produced from auroral chemistry. However, problems remain with all these hypotheses, including the lack of similar behavior at lower altitudes. Our derived mean mixing ratios at 0.5 hPa of (2.4 +/- 0.3) 10(exp -10) for C4H2 and of (1.1 +/- 0.3) 10(exp -9) for CH3C2H are compatible with the analysis of global-average ISO observations performed by Moses et al. Finally, we provide values for the ratios [CH3C2H]/[C2H2] and [C4H2]/[C2H2] that can constrain the coupled chemistry of these hydrocarbons.

Guerlet, Sandrine; Fouchet, Thierry; Bezard, Bruno; Moses, Julianne I.; Fletcher, Leigh N.; Simon-Miller, Amy A.; Flasar, F. Michael

2010-01-01

185

Using Inscribed Angles and Polygons  

NSDL National Science Digital Library

This unit will teach you about inscribed angles, intercepted arcs, their measures, inscribed polygons, and their associated theorems. OK, time for notes! Define Inscribed Angles, using the following website (Only define the inscribed angle from this site): Inscribed Angle Definition Using this new idea, you can use the following activity to figure out the formula for the measure of an inscribed angle: Inscribed Angle Formula Discovery The whole lesson depends upon this definition. Define Intercepted Arc, Inscribed polygons, ...

Neubert, Mrs.

2011-03-10

186

High angle of attack hypersonic aerodynamics  

NASA Technical Reports Server (NTRS)

A new aerodynamics force model is presented which is based on modified Newtonian theory and empirical correlations. The algebraic model was developed for complete vehicles from take off to orbital speeds and for large angles of attack. Predictions are compared to results for a wind tunnel model at a Mach number of 20, and the full scale Shuttle Orbiter for Mach numbers from 0.25 to 20 for angles of attack from 0 to 50 deg. The maximum shuttle orbiter lift/drag at Mach 10 and 20 is 1.85 at 20-deg angle-of-attack. Aerodynamic force predictions are made for a transatmospheric vehicle, which is a derivative of the Shuttle Orbiter, for Mach numbers from 4 to 27 at angles of attack from 5 to 40 deg. Predicted aerodynamic force data indicate that lift/drag ratios of 5.2 at Mach number 10 and 3.6 at Mach number 26 are obtainable. Changes in force coefficients with changes in: nose angle, sweep angle, and (volume exp 2/3)/planform area are quantified for Mach numbers of 10 and 26. Lift/drag ratios increase with decreasing nose angle and (volume exp 2/3)/planform area and increasing wing sweep angle. Lift/drag ratios are independent of these variables for angles of attack in excess of 20 deg at Mach 10 and 30 deg at Mach 26.

Harloff, Gary J.

1987-01-01

187

Yaw Angle Demonstration  

NASA Technical Reports Server (NTRS)

The Large Angle Magnetic Suspension Test Fixture (LAMSTF) is a 5 degree-of -freedom repulsive force magnetic suspension system designed to study the control of objects over large magnetic gaps. A digital control algorithm uses 6 sets of laser-sheet sensors and 5 control coils to position a cylinder 3' above the plane of electromagnetics

1994-01-01

188

Casting and Angling.  

ERIC Educational Resources Information Center

As part of a series of books and pamphlets on outdoor education, this manual consists of easy-to-follow instructions for fishing activities dealing with casting and angling. The manual may be used as a part of the regular physical education program in schools and colleges or as a club activity for the accomplished weekend fisherman or the…

Smith, Julian W.

189

Investigation of Lightning Rod Shielding Angle  

NASA Astrophysics Data System (ADS)

This paper studies those parameters affecting the shielding angle of the lightning rod (Franklin Rod) above very tall buildings. It was recommended that the shielding angle of the lightning rod is about 45°?60°. The downward lightning leader is modeled by using discrete line charges to consider the exponential distribution of charges through the downward leader. The voltage condition used by Rizk is used to investigate the inception of the upward lightning leader. Different air conditions (relative air density and air humidity) are considered for more practical simulation. The influences of lightning parameters and lightning rod height on the shielding angle are studied. The results shows that, lightning leader parameters, lightning rod height and ground slope have series effects on the lightning rod shielding angle. Based on the results, a lightning rod shielding angle for shielding design is recommended to decrease the lightning stroke to the lightning rod.

Nayel, Mohamed

190

Near-Nadiral Normalized Radar Cross Section of the SEA Surface at Ku, Ka, and W-Bands: Comparison of Measurements and Models  

NASA Technical Reports Server (NTRS)

Understanding the relationship between wind speed and direction and the near-nadiral normalized radar cross section (NRCS) of the sea surface is important in many oceanographic and atmospheric remote sensing applications: (1) wind speed retrievals in traditional altimeter systems (2) assistance in calibration and path integrated attenuation processing for atmospheric profiling radars The desired wind speed (and direction in some cases) retrieval requires a clear understanding of the relationship between the relevant geophysical quantities and the observed NRCS Such understanding is available from existing electromagnetic models, but the presence of many such models, as well as implicit descriptions of the sea surface, motivates continued evaluation of model performance.

Majurec, Ninoslav; Johnson, Joel T.; Tanelli, Simone; Durden, Stephen

2012-01-01

191

A Different Angle on Perspective  

ERIC Educational Resources Information Center

When a plane figure is photographed from different viewpoints, lengths and angles appear distorted. Hence it is often assumed that lengths, angles, protractors, and compasses have no place in projective geometry. Here we describe a sense in which certain angles are preserved by projective transformations. These angles can be constructed with…

Frantz, Marc

2012-01-01

192

Uncertainty in T(1) mapping using the variable flip angle method with two flip angles.  

PubMed

Propagation of errors, in conjunction with the theoretical signal equation for spoiled gradient echo pulse sequences, is used to derive a theoretical expression for uncertainty in quantitative variable flip angle T(1) mapping using two flip angles. This expression is then minimized to derive a rigorous expression for optimal flip angles that elucidates a commonly used empirical result. The theoretical expressions for uncertainty and optimal flip angles are combined to derive a lower bound on the achievable uncertainty for a given set of pulse sequence parameters and signal-to-noise ratio (SNR). These results provide a means of quantitatively determining the effect of changing acquisition parameters on T(1) uncertainty. PMID:19060359

Schabel, Matthias C; Morrell, Glen R

2009-01-01

193

Statistics of remote roll angle measurement.  

PubMed

Remote measurement of object orientation is used in various scientific fields, such as robotics, optics, and biology (e.g., optical tweezers). Roll angle is one of the three angles that describe the orientation of an object in space. A common method to measure the roll angle is based on analyzing the polarization of the backreflection of a beam. The accuracy of the measurement is degraded by low signal-to-noise ratio (SNR). The low SNR is the result of the large distance between the measurement device and the object, or due to the small backreflection cross section. We perform a laboratory experiment and derive a mathematical model for the probability density function of the measured roll angle and its expectation value. This model makes it possible to calculate the accuracy of the roll angle measurement at low SNRs. Experiments and theoretical analysis using our model were performed and good agreement between the two approaches has been found. PMID:24787415

Plosker, Effie; Arnon, Shlomi

2014-04-10

194

Laser angle sensor  

NASA Technical Reports Server (NTRS)

A laser angle measurement system was designed and fabricated for NASA Langley Research Center. The instrument is a fringe counting interferometer that monitors the pitch attitude of a model in a wind tunnel. A laser source and detector are mounted above the model. Interference fringes are generated by a small passive element on the model. The fringe count is accumulated and displayed by a processor in the wind tunnel control room. This report includes optical and electrical schematics, system maintenance and operation procedures.

Pond, C. R.; Texeira, P. D.

1985-01-01

195

Surface nanobubble contact angles  

Microsoft Academic Search

Previous AFM experiments on surface nanobubbles have suggested an anomalously large contact angle theta of the bubbles (typically ˜160,o measured through the water) and a possible size dependence theta(R). Here we determine theta(R) for nanobubbles on smooth highly orientated pyrolytic graphite (HOPG) with a variety of different cantilevers. It is found that theta(R) is constant within the experimental error, down

Bram Borkent; Sissi de Beer; Frieder Mugele; Detlef Lohse

2009-01-01

196

Ejs Brewsterâs Angle Model  

NSDL National Science Digital Library

The Ejs Brewsterâs Angle model displays the electric field of an electromagnetic wave incident on a change of index of refraction. The simulation allows an arbitrarily linearly (in parallel and perpendicular components) polarized wave to encounter the change of index of refraction. The initial electric field and incidence angle change of index of refraction can all be changed via sliders. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Brewsterâs Angle model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_waves_brewster.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for wave optics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Aguirregabiria, Juan

2008-08-20

197

Implant Angle Repeatability on Optima MD  

NASA Astrophysics Data System (ADS)

A very sensitive channeling implant has been used to quantify the repeatability of implant angles for the Optima MD over a period exceeding one month. Sensitivity of sheet resistance to variation in vertical and horizontal beam angles was measured for 500 keV P++ at a dose of 5E13 /cm2 near orientations tilt/twist of 0°/0° and 35.26°/0° for (100) wafers. Sensitivity to tilt in the vertical plane at both conditions was at least a 10% change in Rs for a 0.5° change in tilt at a tilt of 0.75° away from the channel (i.e. at 0.75°/0° and 34.5°/0°), where the variation in Rs was linear with tilt. Horizontal angle sensitivity resulted in a 7.5% change in Rs for a 0.5° change in angle, but was less sensitive to smaller angle variation, since Rs varied roughly as a second order function near the channel. Sensitivity to tilt is reduced by about a factor of 3 for implants at 0°/0° compared to 0.75°/0° with a similar response at 35.26°/0° compared to 34.5°/0°. Implants were carried out using wafers from a single boule over a period exceeding one month at the orientation of 0.75°/0°. Angle control was enabled by in-situ measurement and correction of the beam angles in both the vertical and horizontal planes prior to implant. The repeatability of sheet resistance was used to infer the variation in angle. Attributing all Rs variation to be the result of beam angle variation showed that the standard deviation of beam angles for over 30 wafers is 0.03°.

Rathmell, Robert; David, Jonathan; Harris, Mark

2008-11-01

198

Angle Performance on Optima XE  

NASA Astrophysics Data System (ADS)

Angle control on high energy implanters is important due to shrinking device dimensions, and sensitivity to channeling at high beam energies. On Optima XE, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through a series of narrow slits, and any angle adjustment is made by steering the beam with the corrector magnet. In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen during implant. Using a sensitive channeling condition, we were able to quantify the angle repeatability of Optima XE. By quantifying the sheet resistance sensitivity to both horizontal and vertical angle variation, the total angle variation was calculated as 0.04° (1?). Implants were run over a five week period, with all of the wafers selected from a single boule, in order to control for any crystal cut variation.

David, Jonathan; Satoh, Shu

2011-01-01

199

Wide Angle Movie  

NASA Technical Reports Server (NTRS)

This brief movie illustrates the passage of the Moon through the Saturn-bound Cassini spacecraft's wide-angle camera field of view as the spacecraft passed by the Moon on the way to its closest approach with Earth on August 17, 1999. From beginning to end of the sequence, 25 wide-angle images (with a spatial image scale of about 14 miles per pixel (about 23 kilometers)were taken over the course of 7 and 1/2 minutes through a series of narrow and broadband spectral filters and polarizers, ranging from the violet to the near-infrared regions of the spectrum, to calibrate the spectral response of the wide-angle camera. The exposure times range from 5 milliseconds to 1.5 seconds. Two of the exposures were smeared and have been discarded and replaced with nearby images to make a smooth movie sequence. All images were scaled so that the brightness of Crisium basin, the dark circular region in the upper right, is approximately the same in every image. The imaging data were processed and released by the Cassini Imaging Central Laboratory for Operations (CICLOPS)at the University of Arizona's Lunar and Planetary Laboratory, Tucson, AZ.

Photo Credit: NASA/JPL/Cassini Imaging Team/University of Arizona

Cassini, launched in 1997, is a joint mission of NASA, the European Space Agency and Italian Space Agency. The mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

1999-01-01

200

Shapes and Angles  

NSDL National Science Digital Library

In this activity (page 7 of PDF), learners will identify the general two-dimensional geometric shape of the uppermost cross section of an impact crater. They will also draw connections between the general two-dimensional geometric shape of an impact crater and the projectile's angle of impact. There are two versions of this activity: Challenge, where students construct a launcher and create their own craters; and Non-Challenge where students analyze pictures of craters. The Moon Math: Craters! guide follows a 5E approach, applying concepts of geometry, modeling, data analysis to the NASA lunar spacecraft mission, LCROSS.

Nasa

2012-05-08

201

Variable angle correlation spectroscopy  

SciTech Connect

In this dissertation, a novel nuclear magnetic resonance (NMR) technique, variable angle correlation spectroscopy (VACSY) is described and demonstrated with {sup 13}C nuclei in rapidly rotating samples. These experiments focus on one of the basic problems in solid state NMR: how to extract the wealth of information contained in the anisotropic component of the NMR signal while still maintaining spectral resolution. Analysis of the anisotropic spectral patterns from poly-crystalline systems reveal information concerning molecular structure and dynamics, yet in all but the simplest of systems, the overlap of spectral patterns from chemically distinct sites renders the spectral analysis difficult if not impossible. One solution to this problem is to perform multi-dimensional experiments where the high-resolution, isotropic spectrum in one dimension is correlated with the anisotropic spectral patterns in the other dimensions. The VACSY technique incorporates the angle between the spinner axis and the static magnetic field as an experimental parameter that may be incremented during the course of the experiment to help correlate the isotropic and anisotropic components of the spectrum. The two-dimensional version of the VACSY experiments is used to extract the chemical shift anisotropy tensor values from multi-site organic molecules, study molecular dynamics in the intermediate time regime, and to examine the ordering properties of partially oriented samples. The VACSY technique is then extended to three-dimensional experiments to study slow molecular reorientations in a multi-site polymer system.

Lee, Y.K. [Univ. of California, Berkeley, CA (United States)]|[Lawrence Berkeley Lab., CA (United States). Chemical Biodynamics Div.

1994-05-01

202

A Note on Angle Construction  

ERIC Educational Resources Information Center

The author investigates the construction of angles (using Euclidean tools) through a numerical approach. He calls attention to the surprising impossibility of constructing the conventional units of angle measure--the degree, minute, second, radian, and mil. (MN)

Francis, Richard L.

1978-01-01

203

Triangles: Finding Interior Angle Measures  

NSDL National Science Digital Library

In this lesson plan, students will start with a hands-on activity and then experiment with a GeoGebra-based computer model to investigate and discover the Triangle Angle Sum Theorem. Then they will use the Triangle Angle Sum Theorem to write and solve equations and find missing angle measures in a variety of examples.

2012-11-25

204

Sun angle calculator  

NASA Technical Reports Server (NTRS)

A circular computer and system is disclosed for determining the sun angle relative to the horizon from any given place and at any time. The computer includes transparent, rotatably mounted discs on both sides of the circular disc member. Printed on one side of the circular disc member are outer and inner circular sets of indicia respectively representative of site longitude and Greenwich Mean Time. Printed on an associated one of the rotatable discs is a set of indicia representative of Solar Time. Printed on the other side of the circular disc member are parallel lines representative of latitude between diametral representations of North and South poles. Elliptical lines extending between the North and South poles are proportionally disposed on the surface to scale Solar Time in hours.

Flippin, A.; Schmitt, A. L. (inventors)

1976-01-01

205

Narrow Angle movie  

NASA Technical Reports Server (NTRS)

This brief three-frame movie of the Moon was made from three Cassini narrow-angle images as the spacecraft passed by the Moon on the way to its closest approach with Earth on August 17, 1999. The purpose of this particular set of images was to calibrate the spectral response of the narrow-angle camera and to test its 'on-chip summing mode' data compression technique in flight. From left to right, they show the Moon in the green, blue and ultraviolet regions of the spectrum in 40, 60 and 80 millisecond exposures, respectively. All three images have been scaled so that the brightness of Crisium basin, the dark circular region in the upper right, is the same in each image. The spatial scale in the blue and ultraviolet images is 1.4 miles per pixel (2.3 kilometers). The original scale in the green image (which was captured in the usual manner and then reduced in size by 2x2 pixel summing within the camera system) was 2.8 miles per pixel (4.6 kilometers). It has been enlarged for display to the same scale as the other two. The imaging data were processed and released by the Cassini Imaging Central Laboratory for Operations (CICLOPS) at the University of Arizona's Lunar and Planetary Laboratory, Tucson, AZ.

Photo Credit: NASA/JPL/Cassini Imaging Team/University of Arizona

Cassini, launched in 1997, is a joint mission of NASA, the European Space Agency and Italian Space Agency. The mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

1999-01-01

206

Optical Fibre Angle Sensor Used in MEMS  

NASA Astrophysics Data System (ADS)

There is a need for displacement and angle measurements in many movable MEMS structures. The use of fibre optical sensors helps to measure micrometre displacements and small rotation angles. Advantages of this type of transducers are their simple design, high precision of processing, low costs and ability of a non-contact measurement. The study shows an analysis of a fibre-optic intensity sensor used for MEMS movable structure rotation angle measurement. An intensity of the light in the photodetector is basically dependent on a distance between a reflecting surface and a head surface of the fibre transmitting arm, and the deflection angle. Experimental tests were made for PMMA 980/1000 plastic fibres, ?NA=33°. The study shows both analytical and practical results. It proves that calculated and experimental characteristics for the analysed transducers are similar.

Golebiowski, J.; Milcarz, Sz; Rybak, M.

2014-04-01

207

Observational evidence of plane parallel model biases: Apparent dependence of cloud optical depth on solar zenith angle  

Microsoft Academic Search

This study directly compares plane parallel model calculations with 1 year of Earth Radiation Budget Satellite shortwave observations at nadir over ocean between 30°S and 30°N. When plane parallel model calculations are matched to the observations on a pixel-by-pixel basis by adjusting cloud fraction and cloud optical depth, the resulting frequency distributions of cloud optical depth show a systematic shift

Norman G. Loeb; Roger Davies

1996-01-01

208

Equilibrium contact angle or the most-stable contact angle?  

PubMed

It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation. PMID:24140073

Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A

2014-04-01

209

Multiple target angle tracking algorithm using predicted angles  

NASA Astrophysics Data System (ADS)

We modify a multiple target angle tracking algorithm presented by Sword, et al. The predicted estimates, instead of the existing estimates, of the target angles are updated by the most recent output of the sensor array to improve the tracking performance of the algorithm for crossing target. Also, the least square solution is modified to avoid abnormally large angular innovations when the target angles are very close. The improved performance of the proposed algorithm is demonstrated by computer simulations.

Park, S. B.; Ryu, C. S.; Lee, K. K.

1994-04-01

210

Cerebellopontine Angle Epidermoids  

PubMed Central

Epidermoids, or congenital cholesteatomas, constitute about 0.2% to 1.5% of intracranial tumors, and 3% to 5% of tumors of the cerebellopontine angle (CPA). We review the surgical management of CPA epidermoids in 13 patients at the House Ear Clinic for the years 1978 to 1993. There were seven male and six female patients, ranging in age from 27 to 59 years (average, 40 years). Tumors ranged in size from 3.5 cm to 7.0 cm, and the surgical approach was tailored to the tumor extent and location. All patients complained at presentation of unilateral hearing loss, and nine had poor speech discrimination (less than 50%) preoperatively. Serviceable hearing was preserved in two patients. Two patients presented with facial nerve symptoms, and four cases had postoperative permanent facial nerve paralysis (House-Brackmann Grade V or VI). There were no surgical deaths. Four patients required second surgeries to remove residual cholesteatoma. Compared with prior series, we describe a higher rate of total tumor removed, as well as a higher rate of second operations, indicating a more aggressive approach to these lesions. ImagesFigure 1Figure 2Figure 3

Doyle, Karen Jo; De la Cruz, Antonio

1996-01-01

211

Lumbar Position Sense with Extreme Lumbar Angle  

PubMed Central

Tasks involving flexed torso postures have a high incidence of low back injuries. Changes in the ability to sense and adequately control low back motion may play a role in these injuries. Previous studies examining position sense errors of the lumbar spine with torso flexion found significant increases in error with flexion. However, there has been little research on the effect of lumbar angle. In this study, the aim of the study was to examine how position sense errors would change with torso flexion as a function of the target lumbar angle. Fifteen healthy volunteers were asked to assume three different lumbar angles (maximum, minimum and mid-range) at three different torso flexion angles. A reposition sense protocol was used to determine a subject's ability to reproduce the target lumbar angles. Reposition sense error was found to increase 69% with increased torso flexion for mid-range target curvatures. With increasing torso flexion, the increase in reposition sense errors suggests a reduction in sensation and control in the lumbar spine that may increase risk of injury. However, the reposition error was smaller at high torso flexion angles in the extreme target curvatures. Higher sensory feedback at extreme lumbar angles would be important in preventing over-extension or over-flexion. These results suggest that proprioceptive elements in structures engaged at limits (such as the ligaments and facet joints), may provide a role in sensing position at extreme lumbar angles. Sensory elements in the muscles crossing the joint may also provide increased feedback at the edges of the range of motion.

Maduri, A.; Wilson, S. E.

2009-01-01

212

Mandibular angle reduction versus mandible reduction.  

PubMed

The terms "mandibular angle reduction" and "reduction angleplasty" refer to operations to reduce the width of the lower face and change a square face to an oval one. Because the terms emphasize the word angle, however, they imply that the operations apply to the mandibular angle. The most frequent complaint after these operations is that the change in the lateral appearance is clear but that the change in the frontal appearance is not noticeable. Such a result is related to the fact that bone resection is performed mainly in the mandibular angle area and is focused particularly on resection of the posterior projection through curved ostectomy. That is, because operations limited to the mandibular angle area cannot properly satisfy patients' requirements, the operation must be applied to a larger area. Therefore, it seems reasonable to change the terms "mandibular angle reduction" and "reduction angleplasty" to "mandible reduction" and "reduction mandibuloplasty." In addition, the most important technique in the operation is the resection of the outer cortex of the mandible. In particular, the corticectomy technique using a reciprocating saw is quite safe and effective for the maximum resection of lateral flaring within a very short time. PMID:15457047

Jin, Hoon; Kim, Byung Gun

2004-10-01

213

The Critical Angle Can Override the Brewster Angle  

ERIC Educational Resources Information Center

As a culminating activity in their study of optics, my students investigate polarized light and the Brewster angle. In this exercise they encounter a situation in which it is impossible to measure the Brewster angle for light reflecting from a particular surface. This paper describes the activity and explains the students' observations.

Froehle, Peter H.

2009-01-01

214

Sun Incidence Angle Analysis of KOMPSAT-2 Payload during Normal Mission Operations  

NASA Astrophysics Data System (ADS)

KOMPSAT-2 will carry MSC (Multi-Spectral Camera) which provides 1m resolution panchromatic and 4m resolution multi-spectral images at the altitude of 685km sun-synchronous mission orbit. The mission operation of KOMSPAT-2 is to provide the earth observation using MSC with nadir pointing. KOMPSAT-2 will also have the capability of roll/pitch tilt maneuver using reaction wheel of satellite as required. In order to protect MSC from thermal distortion as well as direct sunlight, MSC shall be operated within the constraint of sun incidence angle. It is expected that the sunlight will not violate the constraint of sun incidence angle for normal mission operations without roll/pitch maneuver. However, during roll/pitch tilt operations, optical module of MSC may be damaged by the sunlight. This study analyzed sun incidence angle of payload using KOMPSAT-2 AOCS (Attitude and Orbit Control Subsystem) Design and Performance Analysis Software for KOMPSAT-2 normal mission operations.

Kim, Eung-Hyun; Yong, Ki-Lyuk; Lee, Sang-Ryool

2000-12-01

215

Naskah Angling Darma Ambya Madura  

Microsoft Academic Search

ABSTRAK Angling Darma adalah cerita Jawa yang mengisahkan perjalanan seorang raja yang terpaksa meninggalkan kerajaannya sebagai dharma untuk menebus dosa-dosa yang dilakukannya. Angling Darma Ambya Madura ditulis dalam bahasa Madura dialek Sumenep. Oleh kerana proses penulisannya yang diduga melalui teknik penyaduran, versi Madura ini banyak sekali meng- gunakan kata dan ungkapan yang diadaptasi dari bahasa Jawa, sehingga kata dan ungkapan

A. SYUKUR GHAZALI

216

Measuring Angles in Physical Therapy.  

ERIC Educational Resources Information Center

Features articles about physical therapy and its history as related to geometry through measurement of body angles. Includes open-ended worksheets for mathematics activities that introduce students to angle measurement, data analysis, and mathematical tools. Activities include: (1) Making Your Own Goniometer; (2) Range of Motion; (3) Active versus…

Greeley, Nansee; Offerman, Theresa Reardon

1997-01-01

217

Low-Angle Target Tracking.  

National Technical Information Service (NTIS)

This report describes an experiment that was performed to evaluate a new low-angle tracking (LAT) radar technique which uses array antenna technology. The process enables the radar to track targets in elevation in the low-angle region between one beamwidt...

R. VanDeusen W. Steckenreiter

1973-01-01

218

A Viewpoint on the Quantity "Plane Angle"  

NASA Astrophysics Data System (ADS)

Properties of the quantity "plane angle" are explored under the hypothesis that it is a dimensional quantity. The exploration proceeds especially with respect to the physical concept, its mathematical treatment, vector concepts, measurement theory, units of related quantities, engineering pragmatism, and SI. An attempt is made to bring these different relations into a rational, logical and consistent framework, and thus to justify the hypothesis. Various types of vectorial quantities are recognized, and their properties described with an outline of the necessary algebraic manipulations. The concept of plane angle is amplified, and its interdependence with the circular arc is explored. The resulting units of plane angle form a class of similar scales of measurement. Consequences of the confirmed hypothesis are developed for mathematical expressions involving trigonometric functions, rotational volumes and areas, mathematical limits, differentiation and series expansion. Consequences for mechanical rotational quantities are developed, with proposals for revisions to a number of expressions for derived units within SI. A revised definition for the quantity "plane angle" is stated to take account of the developed insights. There is a clear need to reconsider the status of plane angle and some other quantities within the international framework of SI.

Eder, W. E.

1982-01-01

219

Preliminary experimental measurement of isoplanatic angle  

NASA Astrophysics Data System (ADS)

Group 67 has designed and built an isoplanometer, an instrument which remotely measures the isoplanatic angle associated with atmospheric turbulence conditions. The isoplanatic angle is loosely defined as the angular field over which the spatial transfer function of the atmosphere can be assumed to be invariant. Verification of the instrument required nighttime testing using stellar sources to measure current atmospheric conditions. Preliminary results from a verification experiment and a brief description of the instrument are presented. Full instrument verification requires locating the instrument at a better astronomical site; therefore, the data should not be considered a valid characterization of the atmospheric conditions in Lexington, Mass.

Marquis, D.; Winick, K. A.

1989-10-01

220

A polarized discrete ordinate scattering model for simulations of limb and nadir long-wave measurements in 1-D/3-D spherical atmospheres  

NASA Astrophysics Data System (ADS)

This article describes one of the scattering algorithms of the three-dimensional polarized radiative transfer model ARTS (Atmospheric Radiative Transfer Simulator) which has been implemented to study for example the influence of cirrus clouds on microwave limb sounding. The model uses the DOIT (Discrete Ordinate Iterative) method to solve the vector radiative transfer equation. The implementation of a discrete ordinate method is challenging due to the spherical geometry of the model atmosphere which is required for the simulation of limb radiances. The involved numerical issues, which are grid optimization and interpolation methods, are discussed in this paper. Scattering simulations are presented for limb- and down-looking geometries, for one-dimensional and three-dimensional spherical atmospheres. They show the impact of cloud particle size, shape, and orientation on the brightness temperatures and on the polarization of microwave radiation in the atmosphere. The cloud effect is much larger for limb radiances than for nadir radiances. Particle size is a very important parameter in all simulations. The polarization signal is negligible for simulations with completely randomly oriented particles, whereas for horizontally aligned particles with random azimuthal orientation the polarization signal is significant. Moreover, the effect of particle shape is only relevant for oriented cloud particles. The simulations show that it is essential to use a three-dimensional scattering model for inhomogeneous cloud layers.

Emde, C.; Buehler, S. A.; Davis, C.; Eriksson, P.; Sreerekha, T. R.; Teichmann, C.

2004-12-01

221

On the role of visible radiation in ozone profile retrieval from nadir UV/VIS satellite measurements: An experiment with neural network algorithms inverting SCIAMACHY data  

NASA Astrophysics Data System (ADS)

Theoretical evidence has been given on the role of visible (VIS) radiation in enhancing the accuracy of ozone retrievals from satellite data, especially in the troposphere. However, at present, VIS is not being systematically used together with ultraviolet (UV) measurements, even when possible with one single instrument, e.g., the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY). Reasons mainly reside in the defective performance of optimal estimation and regularization algorithms caused by inaccurate modeling of VIS interaction with aerosols or clouds, as well as in inconsistent intercalibration between UV and VIS measurements. Here we intend to discuss the role of VIS radiation when it feeds a retrieval algorithm based on Neural Networks (NNs) that does not need a forward radiative transfer model and is robust with respect to calibration errors. The NN we designed was trained with a set of ozonesondes (OSs) data and tested over an independent set of OS measurements. We compared the ozone concentration profiles retrieved from UV-only with those retrieved from UV plus VIS nadir data taken by SCIAMACHY. We found that VIS radiation was able to yield more than 10% increase of accuracy and to substantially reduce biases of retrieved profiles at tropospheric levels.

Sellitto, P.; Di Noia, A.; Del Frate, F.; Burini, A.; Casadio, S.; Solimini, D.

2012-08-01

222

Taper Angle Evolution in Taiwan Accretionary Wedge  

NASA Astrophysics Data System (ADS)

Liwen Chena,b, Wu-Cheng Chia, Char-Shine Liuc aInstitute of Earth Sciences, Academia Sinica, Taipei, Taiwan bInstitute of Geosciences, National Taiwan University, Taipei, Taiwan cInstitute of Oceanography, National Taiwan University, Taipei, Taiwan The critical taper model, originally developed using onland Taiwan as an example, is governed by force balance of a horizontal compressional wedge. This model has been successfully applied to many mountainous regions around the world. Among them, Taiwan is located in an oblique collision between the Luzon Arc and the Chinese Passive margin. Previous critical taper angle studies of Taiwan are mainly focusing on utilizing land data. In this study we want to extend these studies to offshore region from the subduction zone to collision zone. Here we study the varying taper angles of the double-vergent wedge derived from 1,000 km of reflection seismic profiles in both the pro-wedge and retro-wedge locations. These profiles were collected in the last two decades. For the retro-wedge, the topography slope angle changes from 2 to 8.8 degrees; some of the steep slope suggests that some part of the retrowedge is currently in a super-critical angle state. Such dramatic changes in taper angle probably strongly affect regional sedimentary processes, including slumping, in addition to structural deformation. These complex processes might even help develop a mélange or re-open a closed basin. We are currently working on studying the taper angle evolution of the pro-wedge from subduction to arc-continent collision zone in the offshore region. Though further works are needed, our preliminary results show that the evolution of wedge angles and the geometry of the wedge are closely linked and inseparable. The structures of the subducting plate might have strong influence on the deformation style of the over-riding plate. It would be interesting to combine the angle variation with the structure interpretation of the accretionary wedge, both in the pro- and retro-wedge regions. And the results might help us to better understand the evolution of Taiwan Accretionary Prism.

Chen, L.; Chi, W.; Liu, C.

2011-12-01

223

Angle interferometer cross axis errors.  

National Technical Information Service (NTIS)

The authors have found what appears to be a previously unreported error in the measurement of surface plate flatness and the measurement of angular displacement errors in rotary tables using angle interferometers.

J. B. Bryan D. L. Carter S. L. Thompson

1993-01-01

224

What we Hope to Learn about Global Mineral Dust Aerosols from EOS Multi-Angle Imaging SpectroRadiometer (MISR)  

NASA Technical Reports Server (NTRS)

On global scales, just a few broad atmospheric aerosol compositional groups are commonly observed. Of these, "mineral dust" is the only group which both contains non-spherical particles, and typically has size distributions with enough large particles for particle shape to affect its visible-light-scattering properties. The MISR instrument is scheduled for launch into a 10:30 AM sun-synchronous, polar orbit aboard the EOS Terra satellite in 1999. MISR will measure the upwelling visible radiance from Earth in 4 spectral bands centered at 446, 558, 672, and 866 nm, at each of 9 emission angles spread out in the forward and aft directions along the flight path at +/-70.5 deg, +/-60.0 deg, +/-45.6 deg, +/-26.1deg, and nadir. Over a period of 7 minutes, as the spacecraft flies along, a 360 km wide swath of Earth will successively be viewed by each of the cameras, allowing MISR to sample a very large range of scattering angles; in mid latitudes, the instrument will observe scattering angles between about 60 deg and 160 deg. Global coverage will be acquired about once in 9 days at the equator; the nominal mission lifetime is 6 years. The distinction in single scattering phase function between natural distributions of spherical and randomly oriented, non-spherical particles, with a broad range of aspect ratios, shows up strongly for scattering angles ranging from about 90 deg to near 180 deg. For non-spherical particle distributions, single scattering phase functions tend to be much flatter in this region than for spherical particles. Since MISR samples the relevant range of scattering angles very well, we expect to be able to make critical distinctions between natural distributions of spherical and randomly oriented, non-spherical particles with MISR data. We anticipate that the new multiangle, multispectral data from MISR will also contain other information about particle properties, a major step beyond current spacecraft remote sensing retrievals, which obtain aerosol optical depth based on entirely assumed particle microphysical properties. According to simulations over cloud-free, calm ocean, for pure particles with natural ranges of optical depth, particle size, and indices of refraction, MISR should retrieve column optical depth for all but the darkest particles, to an uncertainty of at most 0.05 or 20%, whichever is larger, even if the particle properties are poorly known. For one common particle type, soot, constraints on the optical depth over dark ocean are very poor. The simulated measurements also should allow us to separate two to four compositional groups based on indices of refraction, and to identify three to four distinct size groups between 0.1 and 2.0 microns characteristic radius at most latitudes. The technique is most sensitive to particle microphysical properties in the "accumulation mode" sizes. where particle scattering undergoes the transition from Rayleigh to large-particle regimes for the MISR wavelengths. Based on these results, we expect to distinguish air masses containing different aerosol types, routinely and globally, with multiangle remote sensing data. Such data complements in situ and field data, which can provide details about aerosol size and composition locally that are needed to assess the radiative effects of aerosols quantitatively. Both field data and correlations in space and time with likely source and sink regions will also be helpful in developing a global picture of mineral dust aerosol budgets. Further work on the expected sensitivity of MISR to natural mixtures of pure particles, including climatologically likely mineral dust components, is currently underway.

Kahn, Ralph

2000-01-01

225

Angles of multivariable root loci  

NASA Technical Reports Server (NTRS)

A generalized eigenvalue problem is demonstrated to be useful for computing the multivariable root locus, particularly when obtaining the arrival angles to finite transmission zeros. The multivariable root loci are found for a linear, time-invariant output feedback problem. The problem is then employed to compute a closed-loop eigenstructure. The method of computing angles on the root locus is demonstrated, and the method is extended to a multivariable optimal root locus.

Thompson, P. M.; Stein, G.; Laub, A. J.

1982-01-01

226

Unitarity Triangle Angle Measurements at BaBar  

SciTech Connect

We present recent results of measurements of the Unitarity Triangle angles alpha, beta and gamma made with the BaBar detector at the PEP-II asymmetric B factory. We present recent results of measurements of the Unitarity Triangle angles alpha, beta and gamma made with the BaBar detector at the PEP-II asymmetric B factory.

Latham, Thomas E.; /SLAC

2005-06-30

227

Return of hunger following a relatively high carbohydrate breakfast is associated with earlier recorded glucose peak and nadir.  

PubMed

The aim of this study is to test the hypothesis that a breakfast meal with high carbohydrate/low fat results in an earlier increase in postprandial glucose and insulin, a greater decrease below baseline in postprandial glucose, and an earlier return of appetite, compared with a low carbohydrate/high fat meal. Overweight but otherwise healthy adults (n?=?64) were maintained on one of two eucaloric diets: high carbohydrate/low fat (HC/LF; 55:27:18% kcals from carbohydrate:fat:protein) versus low carbohydrate/high fat (LC/HF; 43:39:18% kcals from carbohydrate:fat:protein). After 4?weeks of acclimation to the diets, participants underwent a meal test during which circulating glucose and insulin and self-reported hunger and fullness, were measured before and after consumption of breakfast from their assigned diets. The LC/HF meal resulted in a later time at the highest and lowest recorded glucose, higher glucose concentrations at 3 and 4?hours post meal, and lower insulin incremental area under the curve. Participants consuming the LC/HF meal reported lower appetite 3 and 4?hours following the meal, a response that was associated with the timing of the highest and lowest recorded glucose. Modest increases in meal carbohydrate content at the expense of fat content may facilitate weight gain over the long-term by contributing to an earlier rise and fall of postprandial glucose concentrations and an earlier return of appetite. PMID:24819342

Chandler-Laney, Paula C; Morrison, Shannon A; Goree, Laura Lee T; Ellis, Amy C; Casazza, Krista; Desmond, Renee; Gower, Barbara A

2014-09-01

228

Compression failure of angle-ply laminates  

NASA Technical Reports Server (NTRS)

The present work deals with modes and mechanisms of failure in compression of angle-ply laminates. Experimental results were obtained from 42 angle-ply IM7/8551-7a specimens with a lay-up of ((plus or minus theta)/(plus or minus theta)) sub 6s where theta, the off-axis angle, ranged from 0 degrees to 90 degrees. The results showed four failure modes, these modes being a function of off-axis angle. Failure modes include fiber compression, inplane transverse tension, inplane shear, and inplane transverse compression. Excessive interlaminar shear strain was also considered as an important mode of failure. At low off-axis angles, experimentally observed values were considerably lower than published strengths. It was determined that laminate imperfections in the form of layer waviness could be a major factor in reducing compression strength. Previously developed linear buckling and geometrically nonlinear theories were used, with modifications and enhancements, to examine the influence of layer waviness on compression response. The wavy layer is described by a wave amplitude and a wave length. Linear elastic stress-strain response is assumed. The geometrically nonlinear theory, in conjunction with the maximum stress failure criterion, was used to predict compression failure and failure modes for the angle-ply laminates. A range of wave length and amplitudes were used. It was found that for 0 less than or equal to theta less than or equal to 15 degrees failure was most likely due to fiber compression. For 15 degrees less than theta less than or equal to 35 degrees, failure was most likely due to inplane transverse tension. For 35 degrees less than theta less than or equal to 70 degrees, failure was most likely due to inplane shear. For theta less than 70 degrees, failure was most likely due to inplane transverse compression. The fiber compression and transverse tension failure modes depended more heavily on wave length than on wave amplitude. Thus using a single parameter, such as a ratio of wave amplitude to wave length, to describe waviness in a laminate would be inaccurate. Throughout, results for AS4/3502, studied previously, are included for comparison. At low off-axis angles, the AS4/3502 material system was found to be less sensitive to layer waviness than IM7/8551-7a. Analytical predictions were also obtained for laminates with waviness in only some of the layers. For this type of waviness, laminate compression strength could also be considered a function of which layers in the laminate were wavy, and where those wavy layers were. Overall, the geometrically nonlinear model correlates well with experimental results.

Peel, Larry D.; Hyer, Michael W.; Shuart, Mark J.

1991-01-01

229

An Experimental Study on the Iso-Content-Based Angle Similarity Measure.  

ERIC Educational Resources Information Center

Retrieval performance of the iso-content-based angle similarity measure within the angle, distance, conjunction, disjunction, and ellipse retrieval models is compared with retrieval performance of the distance similarity measure and the angle similarity measure. Results show the iso-content-based angle similarity measure achieves satisfactory…

Zhang, Jin; Rasmussen, Edie M.

2002-01-01

230

Evaluation of arctic multibeam sonar data quality using nadir crossover error analysis and compilation of a full-resolution data product  

NASA Astrophysics Data System (ADS)

We document a new high-resolution multibeam bathymetry compilation for the Canada Basin and Chukchi Borderland in the Arctic Ocean – United States Arctic Multibeam Compilation (USAMBC Version 1.0). The compilation preserves the highest native resolution of the bathymetric data, allowing for more detailed interpretation of seafloor morphology than has been previously possible. The compilation was created from multibeam bathymetry data available through openly accessible government and academic repositories. Much of the new data was collected during dedicated mapping cruises in support of the United States effort to map extended continental shelf regions beyond the 200 nm Exclusive Economic Zone. Data quality was evaluated using nadir-beam crossover-error statistics, making it possible to assess the precision of multibeam depth soundings collected from a wide range of vessels and sonar systems. Data were compiled into a single high-resolution grid through a vertical stacking method, preserving the highest quality data source in any specific grid cell. The crossover-error analysis and method of data compilation can be applied to other multi-source multibeam data sets, and is particularly useful for government agencies targeting extended continental shelf regions but with limited hydrographic capabilities. Both the gridded compilation and an easily distributed geospatial PDF map are freely available through the University of New Hampshire?s Center for Coastal and Ocean Mapping (ccom.unh.edu/theme/law-sea). The geospatial pdf is a full resolution, small file-size product that supports interpretation of Arctic seafloor morphology without the need for specialized gridding/visualization software.

Flinders, Ashton F.; Mayer, Larry A.; Calder, Brian A.; Armstrong, Andrew A.

2014-05-01

231

Calibration Plans for the Multi-angle Imaging SpectroRadiometer (MISR)  

NASA Astrophysics Data System (ADS)

The EOS Multi-angle Imaging SpectroRadiometer (MISR) will study the ecology and climate of the Earth through acquisition of global multi-angle imagery. The MISR employs nine discrete cameras, each a push-broom imager. Of these, four point forward, four point aft and one views the nadir. Absolute radiometric calibration will be obtained pre-flight using high quantum efficiency (HQE) detectors and an integrating sphere source. After launch, instrument calibration will be provided using HQE detectors in conjunction with deployable diffuse calibration panels. The panels will be deployed at time intervals of one month and used to direct sunlight into the cameras, filling their fields-of-view and providing through-the-optics calibration. Additional techniques will be utilized to reduce systematic errors, and provide continuity as the methodology changes with time. For example, radiation-resistant photodiodes will also be used to monitor panel radiant exitance. These data will be acquired throughout the five-year mission, to maintain calibration in the latter years when it is expected that the HQE diodes will have degraded. During the mission, it is planned that the MISR will conduct semi-annual ground calibration campaigns, utilizing field measurements and higher resolution sensors (aboard aircraft or in-orbit platforms) to provide a check of the on-board hardware. These ground calibration campaigns are limited in number, but are believed to be the key to the long-term maintenance of MISR radiometric calibration.

Bruegge, C. J.; Duval, V. G.; Chrien, N. L.; Diner, D. J.

1993-01-01

232

Angle imaging: Advances and challenges  

PubMed Central

Primary angle closure glaucoma (PACG) is a major form of glaucoma in large populous countries in East and South Asia. The high visual morbidity from PACG is related to the destructive nature of the asymptomatic form of the disease. Early detection of anatomically narrow angles is important and the subsequent prevention of visual loss from PACG depends on an accurate assessment of the anterior chamber angle (ACA). This review paper discusses the advantages and limitations of newer ACA imaging technologies, namely ultrasound biomicroscopy, Scheimpflug photography, anterior segment optical coherence tomography and EyeCam, highlighting the current clinical evidence comparing these devices with each other and with clinical dynamic indentation gonioscopy, the current reference standard.

Quek, Desmond T L; Nongpiur, Monisha E; Perera, Shamira A; Aung, Tin

2011-01-01

233

Light Scattering at Various Angles  

PubMed Central

The Mie theory of scattering is used to provide new information on how changes in particle volume, with no change in dry weight, should influence light scattering for various scattering angles and particle sizes. Many biological cells (e.g., algal cells, erythrocytes) and large subcellular structures (e.g., chloroplasts, mitochondria) in suspension undergo this type of reversible volume change, a change which is related to changes in the rates of cellular processes. A previous study examined the effects of such volume changes on total scattering. In this paper scattering at 10° is found to follow total scattering closely, but scattering at 45°, 90°, 135°, and 170° behaves differently. Small volume changes can cause very large observable changes in large angle scattering if the sample particles are uniform in size; however, the natural particle size heterogeneity of most samples would mask this effect. For heterogeneous samples of most particle size ranges, particle shrink-age is found to increase large angle scattering.

Latimer, Paul; Pyle, B. E.

1972-01-01

234

High angle of attack: Aerodynamics  

NASA Technical Reports Server (NTRS)

The ability to predict high angle of attack, nonlinear, aerodynamic characteristics of flight vehicles, including aircraft, has made significant progress in the last 25 years using computational tools and analyses. The key technological element which has made these analyses possible is the ability to account for the influence of the shed vortical flow, prevalent in this angle of attack range, on geometries of interest. Using selected analysis techniques, applications have also been made to wing design in order to improve their high speed maneuver performance. Various techniques, associated with different levels of accuracy, exist to model this vortical flow influence. The ones included in this paper cover: suction analogy with extensions; free vortex filaments; free vortex sheet modeling; and Euler and Navier-Stokes solutions. Associated relevant features of vortices are also addressed, including: the wing and flow conditions which cause vortex formation; and how the vortex strength varies with angle of attack and wing sweep.

Lamar, John E.

1992-01-01

235

Low-field microwave absorption in epitaxial La0.7Sr0.3MnO3 films that results from the angle-tuned ferromagnetic resonance in the multidomain state  

NASA Astrophysics Data System (ADS)

We studied magnetic-field-induced microwave absorption in 100-200 nm thick La0.7Sr0.3MnO3 films on SrTiO3 substrate and found a low-field absorption with a very peculiar angular dependence: it appears only in the oblique field and is absent both in the parallel and in the perpendicular orientations. We demonstrate that this low-field absorption results from the ferromagnetic resonance in the multidomain state (domain-mode resonance). Its unusual angular dependence arises from the interplay between the parallel component of the magnetic field that drives the film into multidomain state and the perpendicular field component that controls the domain width through its effect on domain-wall energy. The low-field microwave absorption in the multidomain state can be a tool to probe domain structure in magnetic films with in-plane magnetization.

Golosovsky, M.; Monod, P.; Muduli, P. K.; Budhani, R. C.

2012-05-01

236

Cydonia: Wide Angle Color Image  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Although the resolution of the MOC wide angle cameras is too low to tell much about the geomorphology of the Cydonia region, the images from the red and blue wide angle cameras provide us with two types of information that is of interest in their own right: color and stereoscopic data. Above are a color view and a stereoscopic anaglyph rendition of Geodesy Campaign images acquired by MGS MOC in May 1999. To view the stereo image, you need red/blue '3-D' glasses.

2000-01-01

237

Management of angle closure glaucoma  

PubMed Central

Primary angle closure glaucoma (PACG) is equally prevalent in Indian in Asian population as the primary open angle glaucoma. Eighty-six percent of people with PACG are in Asia, with approximately 48.0% in China, 23.9% in India and 14.1% in southeast Asia. To understand PACG, it is mandatory to understand its classification and type of presentation with the underlying pathophysiology. The treatment options are medical, laser and/or surgical. The present article provides an overview of PACG.

See, Jovina L S; Aquino, Maria Cecilia D; Aduan, Joel; Chew, Paul T K

2011-01-01

238

Direction angle sensitivity of agricultural field backscatter with AIRSAR data  

NASA Technical Reports Server (NTRS)

This paper presents a study of the direction angle sensitivity of radar backscatter from agricultural fields. The direction angle is defined as the angle between the incident plane and the perpendicular to the field row direction. Previous studies have concentrated on comparing the backscatter of agricultural fields imaged with 0, 45, and 90 degree direction angles. In contrast, this study concentrates on the backscatter changes occurring when the direction angle is modified by a few degrees or even by fractions of a degree. This is possible by using the output of the NASA/JPL AIRSAR processor, in which sixteen independent frames are formed, each one corresponding to the same radar scene imaged with a slightly different squint angle. The studied data set is an agricultural area in La Mancha, Spain acquired in June and July 1991 during the EFEDA experiment. This paper describes the observed backscatter variations of the agricultural fields with direction angle measured at P, L, and C bands. As expected, the backscatter is maximum for a 0 degree direction angle. For several fields, the backscatter at P and L bands drops by more than 10 dB for a 5 degree change in direction angle. Furthermore, the sensitivity to the direction angle decreases with increasing vegetation. The variations in backscatter are compared with model predictions. One model, which agrees with scatterometer data, underestimates the observed backscatter variations with direction angle by more than 10 dB. It does not take into account the possible coherent component of the radar signal. We believe the strong direction sensitivity of agricultural field backscatter obtained with SAR data is due to a Bragg resonant effect, resulting in a strong coherent return when the direction angle is zero. The observations are then projected to the case of spaceborne SAR data.

Dubois, Pascale C.; Rignot, Eric; Vanzyl, Jakob J.

1993-01-01

239

Linkage studies in primary open angle glaucoma  

SciTech Connect

Glaucoma is a leading cause of blindness worldwide. The majority of glaucoma is associated with an open, normal appearing anterior chamber angle and is termed primary open angle glaucoma (POAG, MIM 137760). It is characterized by elevated intraocular pressure and onset in middle age or later. A subset of POAG with juvenile onset has recently been linked to chromosome 1q in two families with autosomal dominant inheritance. Eleven pedigrees with autosomal dominant POG (non-juvenile-onset) have been identified in Epirus, Greece. In the present study DNA samples have been collected from 50 individuals from one large pedigree, including 12 affected individuals. Preliminary results of linkage analysis with chromosome 1 microsatellites using the computer program package LINKAGE Version 5.1 showed no linkage with the markers previously linked to juvenile-onset POAG. Further linkage analysis is being pursued, and the results will be presented.

Avramopoulos, D.; Grigoriadu, M. [Institute of Child Health, Athens (Greece); Kitsos, G. [Univ. Eye Clinic of Ioannina (Greece)] [and others

1994-09-01

240

Evaluation of high angle Auger systems. Engineering and economic summary evaluation of high angle Auger coal mining systems and equipment  

Microsoft Academic Search

This report is the result of a study conducted from October 1978 to June 1979. The objective of the study is to quantify and characterize steeply pitching coal reserves and to develop and evaluate high angle augering systems capable of extracting significant amounts of these reserves. The study proposes a concept for a high angle augering system capable of exploiting

J. Wise; H. Sieg; W. D. Shrader

1979-01-01

241

Discovering the Inscribed Angle Theorem  

ERIC Educational Resources Information Center

Learning to play tennis is difficult. It takes practice, but it also helps to have a coach--someone who gives tips and pointers but allows the freedom to play the game on one's own. Learning to act like a mathematician is a similar process. Students report that the process of proving the inscribed angle theorem is challenging and, at times,…

Roscoe, Matt B.

2012-01-01

242

Angles of planar triangular graphs  

Microsoft Academic Search

We give a characterization of all the planar drawings of a triangular graph through a system of equations and inequalities relating its angles, solving a problem that is explicitly mentioned as open by several authors; we also discuss minimalit y properties of the charact erization. The characterization can be used: (1) to decide in linear time whether a given distribution

Giuseppe Di Battista; Luca Vismara

1993-01-01

243

Wide Angle Laser Beam Steering.  

National Technical Information Service (NTIS)

A systematic investigation has been conducted on the wide angle deflection of laser beams by magnetic stripe domains in a magnetic platelet. Techniques for preparing crystals of YIG by liquid phase epitaxy and MnBiSb by evaporation are described. The YIG ...

F. G. Hewitt T. R. Johansen L. J. Kochel E. J. Torok

1973-01-01

244

Leading Edge Receptivity to Sound at Incidence Angles on Parabolic Bodies at Mean Angles of Attack.  

NASA Astrophysics Data System (ADS)

The leading edge receptivity to acoustic waves of two-dimensional parabolic bodies was investigated using a spatial solution of the Navier-Stokes equations in vorticity/stream function form in parabolic coordinates. The free-stream is composed of a uniform flow with a superposed periodic velocity fluctuation of small amplitude. The method follows that of Haddad & Corke(J. Fluid Mech.), 368, 1998 in which the solution for the basic flow and linearized perturbation flow are solved separately. We primarily investigated the effect of the angle of incidence (-180^circ <= ?1 <= 180^circ) of the acoustic waves on the leading edge receptivity of parabolic bodies at mean angles of attack (0^circ <= ?2 <= 7^circ). The results at ?_1=?_2=0^circ quantitatively agree with those of Haddad & Corke, which showed an increase in the receptivity coefficient with increasing angle of attack. Of special interest is an asymmetry in the receptivity coefficient when determined by extrapolation to the leading from the lower or upper sides of the body, which is produced when the sound incidence angles and angles of attack are large.

Corke, T. C.; Erturk, E.

1999-11-01

245

Kernel density estimation applied to bond length, bond angle, and torsion angle distributions.  

PubMed

We describe the method of kernel density estimation (KDE) and apply it to molecular structure data. KDE is a quite general nonparametric statistical method suitable even for multimodal data. The method generates smooth probability density function (PDF) representations and finds application in diverse fields such as signal processing and econometrics. KDE appears to have been under-utilized as a method in molecular geometry analysis, chemo-informatics, and molecular structure optimization. The resulting probability densities have advantages over histograms and, importantly, are also suitable for gradient-based optimization. To illustrate KDE, we describe its application to chemical bond length, bond valence angle, and torsion angle distributions and show the ability of the method to model arbitrary torsion angle distributions. PMID:24746022

McCabe, Patrick; Korb, Oliver; Cole, Jason

2014-05-27

246

Initial Flight Results of the TRMM Kalman Filter  

NASA Technical Reports Server (NTRS)

The Tropical Rainfall Measuring Mission (TRMM) spacecraft is a nadir pointing spacecraft that nominally controls attitude based on the Earth Sensor Assembly (ESA) output. After a potential single point failure in the ESA was identified, the contingency attitude determination method chosen to backup the ESA-based system was a sixth-order extended Kalman filter that uses magnetometer and digital sun sensor measurements. A brief description of the TRMM Kalman filter will be given, including some implementation issues and algorithm heritage. Operational aspects of the Kalman filter and some failure detection and correction will be described. The Kalman filter was tested in a sun pointing attitude and in a nadir pointing attitude during the in-orbit checkout period, and results from those tests will be presented. This paper will describe some lessons learned from the experience of the TRMM team.

Andrews, Stephen F.; Morgenstern, Wendy M.

1998-01-01

247

Initial flight results of the TRMM Kalman filter  

NASA Technical Reports Server (NTRS)

The Tropical Rainfall Measuring Mission (TRMM) spacecraft is a nadir pointing spacecraft that nominally controls attitude based on the Earth Sensor Assembly (ESA) output. After a potential single point failure in the ESA was identified, the contingency attitude determination method chosen to backup the ESA-based system was a sixth-order extended Kalman filter that uses magnetometer and digital sun sensor measurements. A brief description of the TRMM Kalman filter will be given, including some implementation issues and algorithm heritage. Operational aspects of the Kalman filter and some failure detection and correction will be described. The Kalman filter was tested in a sun pointing attitude and in a nadir pointing attitude during the in-orbit checkout period, and results from those tests will be presented. This paper will describe some lessons learned from the experience of the TRMM team.

Andrews, Stephen F.; Morgenstern, Wendy M.

1998-01-01

248

The Peruvian Continental Margin: Results from wide angle seismic Data  

Microsoft Academic Search

Within the scope of the GEOPECO (Geophysical Experiments at the Peruvian Continental Margin) project, seismic investigations along the Pacific margin of Peru were carried out using ocean bottom hydrophones (OBH) and seismometers (OBS) recording marine airgun shots. The structure and the P- wave velocity of the oblique subducting Nazca and overriding South-American Plates from 8°S to 15°S were determined by

A. Krabbenhoeft; J. Bialas; H. Kopp; N. Kukowski; C. Huebscher

2003-01-01

249

High-sensitivity roll-angle interferometer.  

PubMed

A roll-angle interferometer with high sensitivity is presented in this Letter. Two sets of centrosymmetric beams are used to travel through the measurement and reference arms of the roll-angle interferometer, which contains two specific optical devices: wedge prism assembly and wedge mirror assembly. Changes of the optical path in the interferometric arms caused by roll are differential and converted into phase shift through a particular interferometer system. The interferometric beams are a completely common path for the adoption of the centrosymmetric measurement structure, and the cross talk of the straightness, yaw, and pitch errors is avoided. The dead path is minimized, so the stability and the accuracy of the measurement can be greatly enhanced. The experimental results fit well with the theoretical analysis, and a measurement resolution of sub-microradian is achieved experimentally. PMID:24104824

Le, Yanfen; Hou, Wenmei; Hu, Kai; Shi, Kai

2013-09-15

250

Angle-preserving quantized phase embeddings  

NASA Astrophysics Data System (ADS)

We demonstrate that the phase of randomized complex-valued projections of real-valued signals preserves information about the angle, i.e., the correlation, between those signals. This information can be exploited to design quantized angle-preserving embeddings, which represent such correlations using a nite bit-rate. The proposed embeddings generalize known results on binary embeddings and 1-bit compressive sensing and allow us to explore the trade-o between number of measurements and number of bits per measurement, given the bit rate. The freedom provided by this trade-off, which has also been observed in quantized Johnson-Lindenstrauss embeddings, can improve performance at reduced rate in a number of applications.

Boufounos, Petros T.

2013-09-01

251

Failure Modes of Angle Ply Laminates  

Microsoft Academic Search

Experimental investigation of failure of balanced angle-ply laminates under symmetric uniaxial tension revealed three distinct failure modes. The three different modes were observed for reinforcement angles smaller than ±45°, for the ±45° angle ply and for angles larger than ±45°. Comparison of experimental failure loads with theoretical failure loads based on first laminate failure criteria showed good agreement for certain

Assa Rotem; Zvi Hashin

1975-01-01

252

Angle interferometer cross axis errors  

SciTech Connect

Angle interferometers are commonly used to measure surface plate flatness. An error can exist when the centerline of the double comer cube mirror assembly is not square to the surface plate and the guide bar for the mirror sled is curved. Typical errors can be one to two microns per meter. A similar error can exist in the calibration of rotary tables when the centerline of the double comer cube mirror assembly is not square to the axes of rotation of the angle calibrator and the calibrator axis is not parallel to the rotary table axis. Commercial double comer cube assemblies typically have non-parallelism errors of ten milli-radians between their centerlines and their sides and similar values for non-squareness between their centerlines and end surfaces. The authors have developed a simple method for measuring these errors and correcting them by remachining the reference surfaces.

Bryan, J.B.; Carter, D.L.; Thompson, S.L.

1994-01-01

253

CMK Angle Measurements from BABAR  

NASA Astrophysics Data System (ADS)

Constraining CP-violating CKM parameters is an important goal of the B-factories. The BABAR detector at the SLAC B Factory has published many measurements related to the angles of the Unitarity Triangle. This proceeding reports recent measurements of sin2? in B0 ? D(*)+ D(*)- decays as well as ? related measurements from B0 ? D? K0?± decays and B0 (bar B0 ) -> K^ ± ? ^ ? ? 0 decays.

Anderson, Jacob M.

2009-09-01

254

Complete 360° circumferential SSOCT gonioscopy of the iridocorneal angle  

NASA Astrophysics Data System (ADS)

The ocular iridocorneal angle is generally an optically inaccessible area when viewed directly through the cornea due to the high angle of incidence required and the large index of refraction difference between air and cornea (nair = 1.000 and ncornea = 1.376) resulting in total internal reflection. Gonioscopy allows for viewing of the angle by removing the aircornea interface through the use of a special contact lens on the eye. Gonioscopy is used clinically to visualize the angle directly but only en face. Optical coherence tomography (OCT) has been used to image the angle and deeper structures via an external approach. Typically, this imaging technique is performed by utilizing a conventional anterior segment OCT scanning system. However, instead of imaging the apex of the cornea, either the scanner or the subject is tilted such that the corneoscleral limbus is orthogonal to the optical axis of the scanner requiring multiple volumes to obtain complete circumferential coverage of the ocular angle. We developed a novel gonioscopic OCT (GOCT) system that images the entire ocular angle within a single volume via an "internal" approach through the use of a custom radially symmetric gonioscopic contact lens. We present, to our knowledge, the first complete 360° circumferential volumes of the iridocorneal angle from a direct, internal approach.

McNabb, Ryan P.; Kuo, Anthony N.; Izatt, Joseph A.

2014-02-01

255

Multiple incidence angle SIR-B experiment over Argentina  

NASA Technical Reports Server (NTRS)

The Shuttle Imaging Radar (SIR-B), the second synthetic aperture radar (SAR) to fly aboard a shuttle, was launched on October 5, 1984. One of the primary goals of the SIR-B experiment was to use multiple incidence angle radar images to distinguish different terrain types through the use of their characteristic backscatter curves. This goal was accomplished in several locations including the Chubut Province of southern Argentina. Four descending image acquisitions were collected providing a multiple incidence angle image set. The data were first used to assess stereo-radargrammetric techniques. A digital elevation model was produced using the optimum pair of multiple incidence angle images. This model was then used to determine the local incidence angle of each picture element to generate curves of relative brightness vs. incidence angle. Secondary image products were also generated using the multi-angle data. The results of this work indicate that: (1) various forest species and various structures of a single species may be discriminated using multiple incidence angle radar imagery, and (2) it is essential to consider the variation in backscatter due to a variable incidence angle when analyzing and comparing data collected at varying frequencies and polarizations.

Cimino, Jobea; Casey, Daren; Wall, Stephen; Brandani, Aldo; Domik, Gitta; Leberl, Franz

1986-01-01

256

Penetrating facial injury from angle grinder use: management and prevention.  

PubMed

Injuries resulting from the use of angle grinders are numerous. The most common sites injured are the head and face. The high speed disc of angle grinders does not respect anatomical boundaries or structures and thus the injuries produced can be disfiguring, permanently disabling or even fatal. However, aesthetically pleasing results can be achieved with thorough debridement, resection of wound edges and careful layered functional closure after reduction and fixation of facial bone injuries. A series of penetrating facial wounds associated with angle grinder use are presented and the management and prevention of these injuries discussed. PMID:18215305

Carter, Lachlan M; Wales, Craig J; Varley, Iain; Telfer, Martin R

2008-01-01

257

Penetrating facial injury from angle grinder use: management and prevention  

PubMed Central

Injuries resulting from the use of angle grinders are numerous. The most common sites injured are the head and face. The high speed disc of angle grinders does not respect anatomical boundaries or structures and thus the injuries produced can be disfiguring, permanently disabling or even fatal. However, aesthetically pleasing results can be achieved with thorough debridement, resection of wound edges and careful layered functional closure after reduction and fixation of facial bone injuries. A series of penetrating facial wounds associated with angle grinder use are presented and the management and prevention of these injuries discussed.

Carter, Lachlan M; Wales, Craig J; Varley, Iain; Telfer, Martin R

2008-01-01

258

Preferred viewing distance and screen angle of electronic paper displays.  

PubMed

This study explored the viewing distance and screen angle for electronic paper (E-Paper) displays under various light sources, ambient illuminations, and character sizes. Data analysis showed that the mean viewing distance and screen angle were 495 mm and 123.7 degrees. The mean viewing distances for Kolin Chlorestic Liquid Crystal display was 500 mm, significantly longer than Sony electronic ink display, 491 mm. Screen angle for Kolin was 127.4 degrees, significantly greater than that of Sony, 120.0 degrees. Various light sources revealed no significant effect on viewing distances; nevertheless, they showed significant effect on screen angles. The screen angle for sunlight lamp (D65) was similar to that of fluorescent lamp (TL84), but greater than that of tungsten lamp (F). Ambient illumination and E-paper type had significant effects on viewing distance and screen angle. The higher the ambient illumination was, the longer the viewing distance and the lesser the screen angle. Character size had significant effect on viewing distances: the larger the character size, the longer the viewing distance. The results of this study indicated that the viewing distance for E-Paper was similar to that of visual display terminal (VDT) at around 500 mm, but greater than normal paper at about 360 mm. The mean screen angle was around 123.7 degrees, which in terms of viewing angle is 29.5 degrees below horizontal eye level. This result is similar to the general suggested viewing angle between 20 degrees and 50 degrees below the horizontal line of sight. PMID:17049333

Shieh, Kong-King; Lee, Der-Song

2007-09-01

259

The hypotensive effect of selective laser trabeculoplasty depending on iridocorneal angle pigmentation in primary open angle glaucoma patients  

PubMed Central

Introduction Selective laser trabeculoplasty (SLT) is applied to reduce intraocular pressure in primary open angle glaucoma therapy. It selectively subjects trabecular pigmented cells to a pulsed, frequency-doubled Nd:YAG laser. The biostimulatory effect on trabecular macrophages was also postulated even in low-pigmented angles. The aim of the study was to assess the hypotensive effectiveness of SLT depending on the degree of iridocorneal angle pigmentation. Material and methods Sixty-three eyes of 53 patients with primary open angle glaucoma (POAG) were included in this study and than divided into three subgroups, dependind of iridocorneal angle pigmentation. All subjects underwent SLT on 270 degrees of the angle. Intraocular pressure (IOP) was assesed at baseline and 6 weeks after the laser procedure. Results Six weeks post-SLT mean IOP reduction was 2.63 mm Hg. The degree of IOP reduction showed a significant correlation with angle pigmentation. Intraocular pressure fell by 2.06 mm Hg, 2.46 mm Hg and 4.75 mm Hg in subgroups with low, marked and high pigmentation, respectively. Conclusions The SLT procedure most effectively reduces IOP only in the subgroup of POAG patients with marked angle pigmentation and it is equal to clinically succesfull hypontesive therapeutic effect, according to European Glaucoma Society guidelines. However, lower hypotensive effect in other study subjects may also be the valuable addition to pharmacological therapy of glaucoma.

Piekarniak-Wozniak, Anita; Grabska-Liberek, Iwona

2014-01-01

260

Averaging kernel prediction from atmospheric and surface state parameters based on multiple regression for nadir-viewing satellite measurements of carbon monoxide and ozone  

NASA Astrophysics Data System (ADS)

A current obstacle to the observation system simulation experiments (OSSEs) used to quantify the potential performance of future atmospheric composition remote sensing systems is a computationally efficient method to define the scene-dependent vertical sensitivity of measurements as expressed by the retrieval averaging kernels (AKs). We present a method for the efficient prediction of AKs for multispectral retrievals of carbon monoxide (CO) and ozone (O3) based on actual retrievals from MOPITT (Measurements Of Pollution In The Troposphere) on the Earth Observing System (EOS)-Terra satellite and TES (Tropospheric Emission Spectrometer) and OMI (Ozone Monitoring Instrument) on EOS-Aura, respectively. This employs a multiple regression approach for deriving scene-dependent AKs using predictors based on state parameters such as the thermal contrast between the surface and lower atmospheric layers, trace gas volume mixing ratios (VMRs), solar zenith angle, water vapor amount, etc. We first compute the singular value decomposition (SVD) for individual cloud-free AKs and retain the first three ranked singular vectors in order to fit the most significant orthogonal components of the AK in the subsequent multiple regression on a training set of retrieval cases. The resulting fit coefficients are applied to the predictors from a different test set of test retrievals cased to reconstruct predicted AKs, which can then be evaluated against the true retrieval AKs from the test set. By comparing the VMR profile adjustment resulting from the use of the predicted vs. true AKs, we quantify the CO and O3 VMR profile errors associated with the use of the predicted AKs compared to the true AKs that might be obtained from a computationally expensive full retrieval calculation as part of an OSSE. Similarly, we estimate the errors in CO and O3 VMRs from using a single regional average AK to represent all retrievals, which has been a common approximation in chemical OSSEs performed to date. For both CO and O3 in the lower troposphere, we find a significant reduction in error when using the predicted AKs as compared to a single average AK. This study examined data from the continental United States (CONUS) for 2006, but the approach could be applied to other regions and times.

Worden, H. M.; Edwards, D. P.; Deeter, M. N.; Fu, D.; Kulawik, S. S.; Worden, J. R.; Arellano, A.

2013-07-01

261

Simulation analysis of contact angles and retention forces of liquid drops on inclined surfaces.  

PubMed

A simulation study of liquid drops on inclined surfaces is performed in order to understand the evolution of drop shapes, contact angles, and retention forces with the tilt angle. The simulations are made by means of a method recently developed for dealing with contact angle hysteresis in the public-domain Surface Evolver software. The results of our simulations are highly dependent on the initial contact angle of the drop. For a drop with an initial contact angle equal to the advancing angle, we obtain results similar to those of experiments in which a drop is placed on a horizontal surface that is slowly tilted. For drops with an initial contact angle equal to the mean between the advancing and the receding contact angles, we recover previous results of finite element studies of drops on inclined surfaces. Comparison with experimental results for molten Sn-Ag-Cu on a tilted Cu substrate shows excellent agreement. PMID:22812718

Santos, M J; Velasco, S; White, J A

2012-08-14

262

Optimization of the Space Shuttle Entry Guidance Lateral Deadband, Minimum Bank Angle Logic.  

National Technical Information Service (NTIS)

The lateral deadband and minimum bank angle schedule were studied. Results used by the analytic drag control entry guidance system are presented. Lateral deadband limits and configuration were investigated and possible changes in the minimum bank angle sc...

P. B. Bump

1977-01-01

263

OPTOTRAK Measurement of the Quadriceps Angle Using Standardized Foot Positions  

PubMed Central

Objective: While there is evidence to suggest that the magnitude of the quadriceps (Q) angle changes with alterations in foot position, a detailed quantitative description of this relationship has not been reported. Our purpose was to determine the effect of varying foot placement on the magnitude of the Q angle. Design and Setting: A mixed between-within, repeated-measures design was used to compare Q angles derived under static weight-bearing conditions with the feet positioned in self-selected versus standardized stance positions. Subjects: Twenty healthy young-adult men and women with no history of acute injury to or chronic dysfunction of the lower limbs. Measurements: We placed light-emitting diodes bilaterally on the left and right anterior superior iliac spines, the tibial tuberosities, and the midpoints of the patellae to bilaterally define the Q angles. An OPTOTRAK motion-measurement system was used to capture x,y coordinate data at a sampling rate of 60 Hz. These data were subsequently filtered and used to calculate the magnitude of the left and right Q angles. Results: A repeated-measures analysis of variance revealed that when measured statically, Q angles differed significantly between stance positions (P < .001) and limbs (P < .05). Depending on the stance adopted, mean Q angles varied from 7.2° to 12.7° and 11.0° to 16.1° in the left and right lower limbs, respectively. Q-angle measurements taken in conjunction with the Romberg foot position most closely resembled those gathered with the feet in a self-selected stance (Pearson r = 0.86 to 0.92). Conclusions: Q-angle magnitude varies with changes in foot position, increasing or decreasing as the foot rotates internally or externally, respectively. These data demonstrate the need for a standardized foot position for Q-angle measurements.

Livingston, Lori A.; Spaulding, Sandi J.

2002-01-01

264

Large-scale simulations of glancing-angle deposition  

NASA Astrophysics Data System (ADS)

While thin-films grown via glancing-angle deposition have interesting structural, mechanical, and optical properties, the large range of time- and length-scales makes realistic simulations difficult. Accordingly, while activated relaxation processes may be important at long time-scales, here we focus on the deposition process since we expect the effects of shadowing and deposition-induced relaxation to dominate for large deposition angles. In particular, by taking advantage of the speed of recently developed graphical-processing-units (GPUs) we have carried out ``large-scale'' GPU-enhanced MD simulations of Cu/Cu(100) growth up to 20 monolayers (ML) for deposition angles ? (corresponding to the angle with respect to the substrate normal) ranging from 50^o to 85^o and for both random and fixed azimuthal angles. In general, we find good agreement with experimental results for the dependence of thin-film porosity on deposition angle and film-thickness. Results for the dependence of the surface roughness, lateral correlation length and microstructure (e.g. defect density, vacancy density, and strain) on the deposition angle and film thickness will also be presented.

Amar, Jacques; Liu, Xuejing

2012-02-01

265

Huygens lens for angle compensation  

NASA Astrophysics Data System (ADS)

Plasmonic lenses are based on complex combinations of nanoscale high aspect ratio slits. We show that their design can be greatly simplified, keeping similar performance while releasing technological constraints. The simplified system, called Huygens lens, consists in a central aperture surrounded by several identical single mode slits in a thin gold layer that does not rely anymore on surface plasmons. The focusing behaviour with respect to the position and number of slits is investigated, and we demonstrate the interest of this design to get compact array of lenses which are able to compensate the angle of incidence of the incoming wave.

Lévesque, Quentin; Bouchon, Patrick; Pardo, Fabrice; Pelouard, Jean-Luc; Haïdar, Riad

2014-03-01

266

Airfoil Shaped Flow Angle Probe  

NASA Technical Reports Server (NTRS)

The present invention is a force-based instrument that measures local flow angle. The preferred embodiment of the invention has a low aspect ratio airfoil member connected to a mounting base. Using a series of strain gauges located at the connecting portion of the probe, aerodynamic forces on the airfoil member can be converted to strain, which in turn can be converted to local air flow measurements. The present invention has no moving parts and is well suited for measuring flow in a transonic and supersonic regime.

Corda, Stephen (Inventor); Vachon, Michael Jake (Inventor)

2003-01-01

267

Angle-resolved cathodoluminescence spectroscopy  

SciTech Connect

We present a cathodoluminescence spectroscopy technique which combines deep subwavelength excitation resolution with angle-resolved detection capabilities. The cathodoluminescence emission is collected by a paraboloid mirror (effective NA = 0.96) and is projected onto a 2D CCD array. The azimuthal and polar emission pattern is directly deduced from the image. As proof of principle, we use the technique to measure the angular distribution of transition radiation from a single crystalline gold surface under 30 keV electron irradiation. We find that the experiment matches very well with theory, illustrating the potential of this technique for the characterization of photonic structures with deep subwavelength dimensions.

Coenen, Toon; Vesseur, Ernst Jan R.; Polman, Albert

2011-10-03

268

MAGIC SHIMMING: Gradient shimming with magic angle sample spinning  

NASA Astrophysics Data System (ADS)

A simple method to automatically shim NMR samples spinning at the magic angle is introduced based on the gradient shimming approach. The field inhomogeneity along the spinning axis is measured and automatically corrected. The combination of a normal magic angle spinning (MAS) probe, a conventional homospoil gradient, and a set of properly chosen standard room-temperature shims are used to perform the gradient shimming of samples spinning at the magic angle. The resulting 13C NMR adamantane linewidth is less than 1 Hz (0.0078 ppm at 11.7 T).

Nishiyama, Yusuke; Tsutsumi, Yu; Utsumi, Hiroaki

2012-03-01

269

Measurement of Critical Contact Angle in a Microgravity Space Experiment  

NASA Technical Reports Server (NTRS)

Mathematical theory predicts that small changes in container shape or in contact angle can give rise to large shifts of liquid in a microgravity environment. This phenomenon was investigated in the Interface Configuration Experiment on board the USMT,2 Space Shuttle flight. The experiment's "double proboscis" containers were designed to strike a balance between conflicting requirements of sizable volume of liquid shift (for ease of observation) and abruptness of the shift (for accurate determination of critical contact angle). The experimental results support the classical concept of macroscopic contact angle and demonstrate the role of hysteresis in impeding orientation toward equilibrium.

Concus, P.; Finn, R.; Weislogel, M.

1998-01-01

270

Measurement of Critical Contact Angle in a Microgravity Space Experiment  

NASA Technical Reports Server (NTRS)

Mathematical theory predicts that small changes in container shape or in contact angle can give rise to large shifts of liquid in a microgravity environment. This phenomenon was investigated in the Interface Configuration Experiment on board the USML-2 Space Shuttle flight. The experiment's "double proboscis" containers were designed to strike a balance between conflicting requirements of sizable volume of liquid shift (for ease of observation) and abruptness of the shift (for accurate determination of critical contact angle). The experimental results support the classical concept of macroscopic contact angle and demonstrate the role of hysteresis in impeding orientation toward equilibrium.

Concus, P.; Finn, R.; Weislogel, M.

1998-01-01

271

Optimum Projection Angle for Attaining Maximum Distance in a Soccer Punt Kick  

PubMed Central

To produce the greatest horizontal distance in a punt kick the ball must be projected at an appropriate angle. Here, we investigated the optimum projection angle that maximises the distance attained in a punt kick by a soccer goalkeeper. Two male players performed many maximum-effort kicks using projection angles of between 10° and 90°. The kicks were recorded by a video camera at 100 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity, projection angle, projection height, ball spin rate, and foot velocity at impact. The player’s optimum projection angle was calculated by substituting mathematical equations for the relationships between the projection variables into the equations for the aerodynamic flight of a soccer ball. The calculated optimum projection angles were in agreement with the player’s preferred projection angles (40° and 44°). In projectile sports even a small dependence of projection velocity on projection angle is sufficient to produce a substantial shift in the optimum projection angle away from 45°. In the punt kicks studied here, the optimum projection angle was close to 45° because the projection velocity of the ball remained almost constant across all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle and so the optimum projection angle is well below 45°. Key points The optimum projection angle that maximizes the distance of a punt kick by a soccer goalkeeper is about 45°. The optimum projection angle is close to 45° because the projection velocity of the ball is almost the same at all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the optimum projection angle is well below 45° because the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle.

Linthorne, Nicholas P.; Patel, Dipesh S.

2011-01-01

272

Compression failure of angle-ply laminates  

NASA Technical Reports Server (NTRS)

Test results from the compression loading of (+ or - Theta/ - or + Theta)(sub 6s) angle-ply IM7-8551-7a specimens, 0 less than or = Theta less than or = 90 degs, are presented. The observed failure strengths and modes are discussed, and typical stress-strain relations shown. Using classical lamination theory and the maximum stress criterion, an attempt is made to predict failure stress as a function of Theta. This attempt results in poor correlation with test results and thus a more advanced model is used. The model, which is based on a geometrically nonlinear theory, and which was taken from previous work, includes the influence of observed layer waviness. The waviness is described by the wave length and the wave amplitude. The theory is briefly described and results from the theory are correlated with test results. It is shown that by using levels of waviness observed in the specimens, the correlation between predictions and observations is good.

Peel, L. D.; Hyer, M. W.; Shuart, M. J.

1992-01-01

273

Single miniplate osteosynthesis in angle fracture  

PubMed Central

Aim: The present study was designed to study the feasibility of single miniplate osteosynthesis in the fracture of angle of mandible. Materials and Methods: in this study 110 patient were included and treated with single miniplate osteosynthesis at upper border along champy's line of osteosynthesis. Results: All the cases were treated successfully, common complications which we have observed in this study, cosmetic disfigurement, delayed union, infection, wound dehiscence and paresthesia. Conclusion: Single miniplate fixation in unfavorable fracture is questionable and hence these fracture require some alternative method (locking plate, etc.) for fixation.

Singh, R. K.; Pal, U. S.; Agrawal, Amiya; Singh, Geeta

2011-01-01

274

Calculating Angle Lambda (?) Using Zernike Tilt Measurements in Specular Reflection Corneal Topography  

PubMed Central

Purpose To develop a method to calculate the angle ? of the human eye using Zernike tilt measurements in specular reflection corneal topography. Methods The meaning of Zernike tilt in specular reflection corneal topography is demonstrated by measurements on translated artificial surfaces using the VU Topographer. The relationship derived from the translation experiments is used to determine the angle ?. Corneal surfaces are measured for a set of eight different fixation points, for which tilt angles ? are obtained from the Zernike tilt coefficients. The angles ? are used with respect to the fixation target angles to determine angle ? by fitting a geometrical model. This method is validated with Orbscan II's angle-? measurements in 9 eyes. Results The translation experiments show that the Zernike tilt coefficient is directly related to an angle ?, which describes a tilt orientation of the cornea and can therefore be used to derive a value for angle ?. A significant correlation exists between measured values for angle ? with the VU Topographer and the angle ? with the Orbscan II (r=0.95, P<0.001). A Bland-Altman plot indicates a mean difference of -0.52 degrees between the two instruments, but this is not statistically significant as indicated by a matched-pairs Wilcoxon signed-rank test (P?0.1748). The mean precision for measuring angle ? using the VU topographer is 0.6±0.3 degrees. Conclusion The method described above to determine angle ? is sufficiently repeatable and performs similarly to the angle-? measurements made with the Orbscan II.

Braaf, Boy; van de Watering, Thomas Christiaan; Spruijt, Kees; van der Heijde, Rob G.L.; Sicam, Victor Arni D.P.

2010-01-01

275

Turbulence at the magic angle  

NASA Astrophysics Data System (ADS)

Strong turbulence is characterized by the way in which statistical moments of velocity increments < (? u(r))^p > increase with separation, < (? u(r))^p > ~ r^?(p). For isotropic turbulence it is believed that the function ?(p) is a universal function, independent of the way in which turbulence is made. It is also believed that for anisotropic turbulence the function depends in such way on the angle between the vectors u and r that each of the irreducible components of G_p(r, ?, ?) ? < (? u(r))^p > has its own scaling exponent (V.Lvov et al. PRL 79, 2050(1997)). Conversely, scaling of the generalized structure function G_p(r, ?,?) should be purest if only one single component survives. In the case of axisymmetric turbulence, these irreducible components are related to the Legendre polynomials P_l(?), and the magic angle ?M where P_2(?_M) = 0 should be a special one. In an experiment we create axisymmetric turbulence and measure the generalized structure functions G_p(r, ?, ?) using an array of hot-wire probes. We will demonstrate that for the Reynolds numbers (Re_? ? 600) in our experiment the structure functions do not foliate simply in their irreducible components, and that the pureness of the scaling is best when ? = ?/2 (the transverse structure function).

Staicu, Adrian Daniel; van de Water, Willem

2001-11-01

276

Planet Impact: What's Your Angle  

NSDL National Science Digital Library

In this interactive module, students can vary the comet's angle of approach to see the effect of gravity on its trajectory towards Jupiter. The speed and masses of the two bodies are held constant. The goal is for the students to understand the relationship between the distance from the planet and the force of gravity. Students may work independently or in small groups to complete this activity. It may also be done as a teacher-directed activity in the classroom. After completing this module, students will learn about how changing the angle of approach affects the force of gravity on a comet. This module is a part of the online exploration "Planet Impact!" An explanation of the science behind the animations can be found in "Science Scoop." More information on the crash of Shoemaker-Levy 9 on Jupiter can be obtained from "Gravity Gallery" and "Comet News." Detailed teacher pages, identified as Teaching Tips on the title pages of the activity, provide science background information, lesson plan ideas, related resources, and alignment with national education standards.

277

Phenomenological relations for quark and neutrino mixing angles  

SciTech Connect

The most recent experimental data on quark and neutrino mixing angles are discussed. It is indicated that the results of the latest kaon-decay experiments are consistent with the unitarity condition for the first row of the Cabibbo-Kobayashi-Maskawa matrix if the currently available world-average value of the neutron lifetime is used to determine the element V{sub ud} of this matrix. The quark mixing angles are calculated within the Fritzsch-Scadron-Delbourgo-Rupp phenomenological approach on the basis of values of the masses of light and heavy constituent quarks. The neutrino mixing angles are calculated to a high precision with the aid of the hypothesis that the quark and neutrino mixing angles are complementary. The results are compatible with experimental data.

Gaponov, Yu. V.; Khruschov, V. V.; Semenov, S. V. [Russian Research Centre Kurchatov Institute (Russian Federation)

2008-01-15

278

Carrying angle of the elbow - excessive  

MedlinePLUS

... sides and your palms are facing forward, your forearm and hands should normally be about 5 to ... angle" of the elbow. This angle allows your forearms to clear the hips when swinging your arms, ...

279

Failure Modes of Angle Ply Laminates.  

National Technical Information Service (NTIS)

Experimental investigation of failure of balanced angle-ply laminates under symmetric uniaxial tension revealed three distinct failure modes. The three different modes were observed for reinforcement angles smaller than plus or minus 45 degrees, for the p...

A. Rotem Z. Hashin

1974-01-01

280

Moment-angle relations in the initial time of contraction.  

PubMed

Standard moment-angle relations are typically obtained for values at maximum of contraction. Muscle properties for contraction times, similar to the short times of powerful athletic activities, may be more important than muscle properties that are obtained at maximum (TMAX) of contraction. The research question was whether moment-angle relations obtained during the initial time course of contraction are linearly scaled reflections of moment-angle relations obtained at maximum of contraction. The isometric moment of the knee extensor and the electromyographic activity (EMG) of the knee extensor and flexor muscles were measured at 9 knee angles in 22 elite female track and field jumpers. Absolute moments (Nm), relative moments (%TMAX) and EMG integrals were determined at 30 ms, 50 ms, 150 ms and 200 ms from the onset of contraction and at maximum. For moment-angle relations obtained during the initial time course of contraction, there was a shift of the optimum knee angle to a more extended knee. During the initial time course of the contraction, %TMAX moment was greater near full knee extension. The EMG activity was the same across knee angles. The results may have important practical implications for muscular force evaluation for activities where maximum force production is coupled to a short activation time. PMID:20617488

Rousanoglou, E N; Herzog, W; Boudolos, K D

2010-09-01

281

LSNR Airborne LIDAR Mapping System Design and Early Results (Invited)  

NASA Astrophysics Data System (ADS)

Low signal-to-noise ratio (LSNR) detection techniques allow for implementation of airborne light detection and range (LIDAR) instrumentation aboard platforms with prohibitive power, size, and weight restrictions. The University of Florida has developed the Coastal Area Tactical-mapping System (CATS), a prototype LSNR LIDAR system capable of single photon laser ranging. CATS is designed to operate in a fixed-wing aircraft flying 600 m above ground level, producing 532 nm, 480 ps, 3 ?J output pulses at 8 kHz. To achieve continuous coverage of the terrain with 20 cm spatial resolution in a single pass, a 10x10 array of laser beamlets is scanned. A Risley prism scanner (two rotating V-coated optical wedges) allows the array of laser beamlets to be deflected in a variety of patterns, including conical, spiral, and lines at selected angles to the direction of flight. Backscattered laser photons are imaged onto a 100 channel (10x10 segmented-anode) photomultiplier tube (PMT) with a micro-channel plate (MCP) amplifier. Each channel of the PMT is connected to a multi-stop 2 GHz event timer. Here we report on tests in which ranges for known targets were accumulated for repeated laser shots and statistical analyses were applied to evaluate range accuracy, minimum separation distance, bathymetric mapping depth, and atmospheric scattering. Ground-based field test results have yielded 10 cm range accuracy and sub-meter feature identification at variable scan settings. These experiments also show that a secondary surface can be detected at a distance of 15 cm from the first. Range errors in secondary surface identification for six separate trials were within 7.5 cm, or within the timing resolution limit of the system. Operating at multi-photon sensitivity may have value for situations in which high ambient noise precludes single-photon sensitivity. Low reflectivity targets submerged in highly turbid waters can cause detection issues. CATS offers the capability to adjust the sensitivity of the sensor by changing the PMT supply voltage. For heavily turbid water, the multi-photon state (2300 V, 2.5*10^5 gain) was not sufficient for feature identification. Extraction of the bottom signal in a heavily turbid suspension necessitated maximum MCP-PMT gain (2500 V, 8*10^5 gain). Extrapolation of bathymetric test results suggest that the density of data points from the sea bottom should be sufficient to establish near-shore depths (up to 5 m) at a spatial resolution of 1 meter, in moderately turbid water. Initial airborne tests over fresh water lakes in central Florida indicate that scan patterns containing near nadir laser points produce strong returns from the surface of the water that cause oscillations in the PMT—preventing the detection of the lake bottom in shallow clear water. These results suggest that it may be necessary to tilt the sensor head in its mount, or use a scan pattern that does not include nadir points, such as a circular scan, for bathymetric mapping. Additional tests are ongoing to optimize the performance of the CATS LSNR airborne LIDAR system for both high spatial resolution terrain mapping and shallow water bathymetric mapping.

Shrestha, K.; Carter, W. E.; Slatton, K. C.

2009-12-01

282

Presumed topiramate-induced bilateral acute angle-closure glaucoma  

Microsoft Academic Search

PURPOSE: We describe a case of bilateral angle-closure glaucoma associated with oral topiramate therapy.METHODS: Interventional case report. Case report with echographic illustration.RESULTS: A 51-year-old man developed bilateral acute angle-closure glaucoma 2 weeks after beginning topiramate therapy for bipolar affective disorder. Laser peripheral iridotomy was performed in the right eye without resolution of the acute attack. Echography revealed lens thickening and

James T Banta; Kara Hoffman; Donald L Budenz; Elizenda Ceballos; David S Greenfield

2001-01-01

283

Computing the Grazing Angle of Specular Reflection.  

National Technical Information Service (NTIS)

Three methods are given for computing the grazing angle of specular reflection. The first gives an approximation to the grazing angle. The second is an iterative method, whose derivation is easy and provides for the computation of the grazing angle to any...

A. Miller E. Vegh

1982-01-01

284

A new procedure for measuring contact angle  

SciTech Connect

Described here are some recent work regarding the mathematic design of apparatus that exploits microgravity conditions for accurate experimental determination of contact angle. The underlying motivation for the procedures rests on a discontinuous dependence of the capillary free surface interface S on the contact angle {gamma}, in a cylindrical capillary tube whose section (base) {Omega} contains a protruding corner with opening angle 2{alpha}.

Concus, P. [Lawrence Berkeley Lab., CA (United States); Finn, R. [Stanford Univ., CA (United States). Dept. of Mathematics

1994-05-01

285

The significance of normal angle vessels.  

PubMed

One hundred patients (200 eyes) were examined over a one-year period for the presence of normal anterior chamber angle vessels. Normal vessels were observed in the angle in 21% of eyes examined. The types, location, and number of normal vessels are documented. The significance of these vessels in two eyes with anterior chamber angle fixated lenses is discussed. PMID:4022560

Shihab, Z M; Lee, P F

1985-06-01

286

Large-scale molecular dynamics simulations of glancing angle deposition  

NASA Astrophysics Data System (ADS)

Using a computationally efficient method, we have carried out large-scale molecular dynamics simulations of Cu/Cu(100) growth up to 20 monolayers (ML) for deposition angles ranging from 50° to 85° and for both random and fixed azimuthal angles. A variety of quantities including the porosity, roughness, lateral correlation length, average grain size, strain, and defect concentration are used to characterize the thin-film morphology. For large deposition angles (?>=80°), we find well-defined columnar growth while for smaller angles, columnar growth has not yet set in. In addition, for ?=70°-85°, the thin-film porosity and columnar tilt angles (for fixed azimuthal angle ?) are in reasonable agreement with experiments. For both random and fixed ?, the number of grains, average grain-size, and number of surface atoms belonging to (111) facets increase rapidly with deposition angle. As a result, twin facet formation and budding occur in our simulations, in good agreement with experiments. In good qualitative agreement with recent experimental observations, we also find that the average strain is initially compressive but becomes tensile after the onset of columnar growth. Our simulations also reveal that for large deposition angles a variety of unexpected and complex dynamical processes play a key role in determining the evolution of the surface morphology and microstructure. In particular, due to the existence of deposition-induced events, the vacancy density remains very small, even though the defect density is relatively large and increases with deposition angle. In addition, large-scale re-arrangement events as well as thermal (elastic) vibrations lead to large-amplitude oscillations in the columnar growth regime. These oscillations play a key role in promoting rapid coalescence via additional large-scale collective motion, thus, significantly enhancing the coarsening process.

Hubartt, Bradley C.; Liu, Xuejing; Amar, Jacques G.

2013-08-01

287

Reflective properties of randomly rough surfaces under large incidence angles.  

PubMed

The reflective properties of randomly rough surfaces at large incidence angles have been reported due to their potential applications in some of the radiative heat transfer research areas. The main purpose of this work is to investigate the formation mechanism of the specular reflection peak of rough surfaces at large incidence angles. The bidirectional reflectance distribution function (BRDF) of rough aluminum surfaces with different roughnesses at different incident angles is measured by a three-axis automated scatterometer. This study used a validated and accurate computational model, the rigorous coupled-wave analysis (RCWA) method, to compare and analyze the measurement BRDF results. It is found that the RCWA results show the same trend of specular peak as the measurement. This paper mainly focuses on the relative roughness at the range of 0.16angles. The RCWA and the Rayleigh criterion results have been compared, showing that the relative error of the total integrated scatter increases as the roughness of the surface increases at large incidence angles. In addition, the zero-order diffractive power calculated by RCWA and the reflectance calculated by Fresnel equations are compared. The comparison shows that the relative error declines sharply when the incident angle is large and the roughness is small. PMID:24977364

Qiu, J; Zhang, W J; Liu, L H; Hsu, P-F; Liu, L J

2014-06-01

288

Argon-Assisted Glancing Angle Deposition  

NASA Astrophysics Data System (ADS)

Glancing angle deposition (GLAD) is a physical vapour deposition (PVD) technique capable of fabricating highly porous thin films with controllable film morphology on the 10 nm length scale. The GLAD process is flexible and may be used on virtually any PVD-compatible material. This makes GLAD a useful technique in many applications including photovoltaics, humidity sensing, and photonic devices. Conventional, dense films grown at normal incidence concurrent with ion or energetic neutral bombardment have been reported to have higher film density than unbombarded films. In a similar sense, highly porous GLAD films grown with concurrent bombardment should generate films with new interesting properties and extend the versatility of the GLAD process. The research presented in this thesis investigates the use of energetic neutral bombardment during GLAD film growth to produce new film morphologies. Here, with increasing bombardment, the column tilt increases, film density increases, and specific surface area decreases. A film simultaneously exhibiting high column tilt angle and film density is enabled by incorporating bombardment concurrent with GLAD film growth. This in turn results in films with larger principal refractive indices, but a smaller normalized in plane birefringence. Bombarded films were also found to be compatible with the phisweep process which helps decouple the column tilt angle from film density. Characterization of the bombardment-assisted growth process indicates that both sputtering and bombardment-induced diffusion play a role in the modification of film morphology. The film property modifications which arise as a result of bombardment-assisted growth lead to device improvements in a number of applications. Bombardment was used to fabricate square spiral photonic crystal structures with increased column tilt which bear a closer resemblance to optimized simulated structures than conventionally-grown GLAD films. The increase in column tilt angle and film density were found to be beneficial in the fabrication of circular polarization filters, where bombarded films were found to exhibit larger selective circular behaviour than in unbombarded films. The morphology modification was also found to be beneficial in humidity sensing applications where the bombarded films demonstrated an increase in the capacitive response.

Sorge, Jason Brian

289

Influence of temperature on divergence angle of a focal telescope used in laser optical communication.  

PubMed

Divergence angle of antenna is an important parameter in laser optical communication. It determines the power of the receiver terminal. In this paper, the influence of temperature on the divergence angle is discussed. Theoretical analysis and experiment results demonstrate that the relationship between the variance of temperature and of divergence angle is linear. PMID:22714349

Zheng, Guoxian; Zhou, Feng; Liu, Jianfeng; Li, Tuotuo; An, Ning; Zhang, Binglong

2012-06-01

290

Acceptance-angle measurement of multimode fibers - A comparison of techniques  

Microsoft Academic Search

A number of techniques for measuring multimode fiber acceptance angle are described, and the general requirements and problems particular to each technique are discussed. An experimental comparison is presented of a fiber acceptance-angle technique and a fiber radiation-angle technique. Results are presented on quasi-step index and also plastic-clad silica fibers. It is concluded that the radiation-angle technique offers simplicity of

R. Worthington

1982-01-01

291

Low Angle Normal Fault, Fossil or Active?  

NASA Astrophysics Data System (ADS)

The Panamint Valley - Hunter Mountain - Saline Range (PHS) faults are, together with the Death Valley and Owens Valley faults, one of the three major fault zones within the Eastern California Shear Zone (ECSZ). The ECSZ is the most active fault system bounding the Basin and Range to the southwest with approximately 10 mm/yr of cumulative slip along strike-slip and trans-tensional segments. Previous work has identified the Panamint Valley and Saline Range faults as low angle normal faults and the Hunter Mountain as a transfer fault (Wesnousky and Jones, 1994). A debate exists whether this system is active at present time. Interferometry Synthetic Aperture Radar (InSAR) is a geodetic technique that allows measurement of ground motion at a mm/yr accuracy over large areas with a high measurement sampling. We processed a large number of data to investigate ground motion in the PHS fault system to shed light on the interseismic strain accumulation and its relation to the fault geometry. Preliminary results indicate high strain rate over the Hunter Mountain fault. The locking depth of the fault inferred from elastic modeling of interseismic strain accumulation is on the order of 4km, significantly shallower than for neighboring faults. In contrast, the long wavelength strain field across the Panamint and Saline faults indicates possibly deeper locking depths and/or shallower dip. The shallow locking depth of 4km inferred for the Hunter Mountain fault corresponds with the extension at depth of the two bounding low angle normal faults below Hunter Mountain, suggesting a control by the low angle normal fault system.

Gourmelen, N.; Falk, A.; Manzo, M.; Francesco, C.; Lanari, R.; Johnson, K.

2007-12-01

292

Adaptive Control of a Vibratory Angle Measuring Gyroscope  

PubMed Central

This paper presents an adaptive control algorithm for realizing a vibratory angle measuring gyroscope so that rotation angle can be directly measured without integration of angular rate, thus eliminating the accumulation of numerical integration errors. The proposed control algorithm uses a trajectory following approach and the reference trajectory is generated by an ideal angle measuring gyroscope driven by the estimate of angular rate and the auxiliary sinusoidal input so that the persistent excitation condition is satisfied. The developed control algorithm can compensate for all types of fabrication imperfections such as coupled damping and stiffness, and mismatched stiffness and un-equal damping term in an on-line fashion. The simulation results show the feasibility and effectiveness of the developed control algorithm that is capable of directly measuring rotation angle without the integration of angular rate.

Park, Sungsu

2010-01-01

293

ILC Extraction Line for 14 mrad Crossing Angle  

SciTech Connect

The earlier studies of the ILC extraction line for 20 mrad and 2 mrad crossing angle options [1]-[5] showed that the 20 mrad design has an advantage of a simpler beamline and lower extraction beam loss because of the independent incoming and extraction optics. However, the large 20 mrad crossing angle requires the use of a crab cavity correction, increases synchrotron radiation emittance growth in the solenoid, and increases photon backscattering from the forward calorimeter of the detector. To reduce these effects, an attempt has been made to minimize the crossing angle while keeping the extraction and incoming lines separate. A new quadrupole scheme near the interaction point has been proposed which allows a reduction of the crossing angle to 14 mrad [6]. The optics design and results of tracking and background simulations for the 14 mrad extraction line are presented.

Nosochkov, Y.; Markiewicz, T.; Maruyama, T.; Seryi, A.; /SLAC; Parker, B.; /Brookhaven

2005-12-08

294

Mirror, Mirror on the Wall: Angles of Reflection  

NSDL National Science Digital Library

In this activity, students mount a covered mirror on a wall at eye level, then work in pairs to predict where two people must stand so each can see the other's reflection in the mirror. Each pair will discuss and agree on the places where they think they must stand, then remove the cover from the mirror and test their predictions. As an extension of this activity, they can design and construct large protractors out of cardboard to measure their angles of incidence and reflection and draw and record their results in their science notebooks. Each team of students should be able to explain to another group how they constructed the protractors and how they used them to measure the angles. A link is provided to an interactive Java tutorial on angles of reflection where students can explore how light reflects off a mirror at different angles.

295

Folded cavity angled-grating broad-area lasers.  

PubMed

The angled-grating broad-area laser is a promising candidate for high power, high brightness diode laser source. The key point in the design is the angled gratings which can simultaneously support the unique snake-like zigzag lasing mode and eliminate the direct Fabry-Perot (FP) feedback. Unlike a conventional laser waveguide mode, the phase front of the zigzag mode periodically changes along the propagation direction. By use of the mirror symmetry of the zigzag mode, we propose and demonstrate the folded cavity angled-grating broad-area lasers. One benefit of this design is to reduce the required wafer space compared to a regular angled-grating broad-area laser, especially in a long cavity laser for high power operation. Experimental results show that the folded cavity laser exhibits good beam quality in far field with a slightly larger threshold and smaller slope efficiency due to the additional interface loss. PMID:24104317

Zhao, Yunsong; Zhu, Lin

2013-10-01

296

Multi-angle technique for measurement of ground source emission  

SciTech Connect

TAISIR, the Temperature and Imaging System Infrared, is a nominally satellite based platform for remote sensing of the earth. One of its design features is to acquire atmospheric data simultaneous with ground data, resulting in minimal dependence on external atmospheric models for data correction. One technique we employ to acquire atmospheric data is a true multi-angle data acquisition technique. Previous techniques have used only two angles. Here we demonstrate the advantage of using a large number of viewing angles to overconstrain the inversion problem for critical atmospheric and source parameters. For reasonable data acquisition scenarios, simulations show source temperature errors of less than 1K should be possible. Tradeoffs between flight geometry, number of look angles,, and system signal-to-noise are given for typical parameter ranges.

Henderson, J.R.

1995-04-01

297

Large-scale Molecular Dynamics Simulations of Glancing Angle Deposition  

NASA Astrophysics Data System (ADS)

While a variety of methods have been developed to carry out atomistic simulations of thin-film growth at small deposition angles with respect to the substrate normal, due to the complex morphology as well as the existence of multiple scattering of depositing atoms by the growing thin-film, realistically modeling the deposition process for large deposition angles can be quite challenging. Accordingly, we have developed a computationally efficient method based on the use of a single graphical processing unit (GPU) to carry out molecular dynamics (MD) simulations of the deposition and growth of thin-films via glancing angle deposition. Using this method we have carried out large-scale MD simulations, based on an embedded-atom-method potential, of Cu/Cu(100) growth up to 20 monolayers for deposition angles ranging from 50^o to 85^o and for both random and fixed azimuthal angles. Our results for the thin-film porosity, roughness, lateral correlation length, and density vs height will be presented and compared with experiments. Results for the dependence of the microstructure, grain-size distribution, surface texture, and defect concentration on deposition angle will also be presented.

Hubartt, Bradley; Liu, Xuejing; Amar, Jacques

2013-03-01

298

Contact angle interpretation: re-evaluation of existing contact angle data  

Microsoft Academic Search

We have recently shown that static contact angles measured by conventional goniometer techniques could be meaningless in the context of the Young equation. There is an abundance of contact angles in the literature that are of unknown status. Here, we explored whether one should completely neglect the literature contact angle data. Existing static contact angles for 34 different types of

D. Y. Kwok; A. W. Neumann

2000-01-01

299

Anomalous and resonance small angle scattering  

SciTech Connect

Significant changes in the small angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous dispersion terms for the scattering factor (x-rays) or scattering length (neutrons). The physics inherent in these anomalous dispersion terms is first discussed before considering how they enter the relevant scattering theory. Two major areas of anomalous scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with x-rays. However, it is pointed out that the formalism is the same or the analogue experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small-angle neutron scatterings are discussed. 8 figs.

Epperson, J.E.; Thiyagarajan, P.

1987-11-01

300

Anomalous and resonance small angle scattering: Revision  

SciTech Connect

Significant changes in the small angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous dispersion terms for the scattering factor (x-rays) or scattering length (neutrons). The physics inherent in these anomalous dispersion terms is first discussed before considering how they enter the relevant scattering theory. Two major areas of anomalous scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with x-rays. However, it is pointed out that the formalism is the same for the analogue experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small angle neutron scatterings are discussed. 54 refs., 8 figs., 1 tab.

Epperson, J.E.; Thiyagarajan, P.

1987-11-01

301

Scaling effects in angle-ply laminates  

NASA Technical Reports Server (NTRS)

The effect of specimen size upon the response and strength of +/- 45 degree angle-ply laminates was investigated for two graphite fiber reinforced plastic systems and several stacking sequences. The first material system was a brittle epoxy based system, AS4 fibers in 3502 epoxy, and the second was a tough thermoplastic based system, AS4 fibers in PEEK matrix. For the epoxy based system, two generic +/- 45 degree lay-ups were studied: (+45 degrees sub n/-45 degrees sub n) sub 2S (blocked plies), and (+45 degrees/-45 degrees) sub 2nS, for n=1 and 2. The in-plane dimensions of the specimens were varied such that the width/length relationship was 12.7 x n/127 x n mm, for m=1, 2, 3, or 4. It is shown that the stress/strain response and the ultimate strength of these angle-ply laminates depends on the laminate thickness and the type of generic lay-up used. Furthermore, it is shown that first ply failure occurs in the surface plies as a result of normal rather than shear stresses. The implications of the experimental findings upon the validity of the +/- 45 degree tensile test which is used to determine the in-plane shear response of unidirectional composites are discussed.

Kellas, Sotiris; Morton, John

1992-01-01

302

Themis observations of whistler wave normal angles  

NASA Astrophysics Data System (ADS)

Since spring 2007, the five Themis spacecraft have monitored the vicinity of Earth along orbits, which reach from the dayside solar wind until far down Earth's magnetotail. A magnetometer (SCM) and an electric field instrument (EFI) onboard Themis can be operated in a wave-burst mode which allows for sampling of magnetic and electric waveforms with a rate of up to 8192 Hz. These waveform snapshots have been subject to spectral and polarization analysis. The computed parameters fill a database which is established in the frame of the MAARBLE project ("Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss"). Among those parameters is the direction of the wave-vector with respect to the ambient magnetic field. We present first results on the distribution of those wave normal angles from whistler mode emission. While propagating away from the source region, wave normal angles of whistler are believed to change from parallel to more oblique orientations. We study the wave-vectors both on the nightside, where source regions are close to the equatorial plane, and on the dayside, where sources can also be found at high latitudes.

Taubenschuss, Ulrich; Khotyaintsev, Yuri; Vaivads, Andris; Santolik, Ondrej; Cully, Christopher; LeContel, Olivier; Angelopoulos, Vassilis

2014-05-01

303

Wave-angle control of delta evolution  

NASA Astrophysics Data System (ADS)

Wave-influenced deltas, with large-scale arcuate shapes and demarcated beach ridge complexes, often display an asymmetrical form about their river channel. Here, we use a numerical model to demonstrate that the angles from which waves approach a delta can have a first-order influence upon its plan-view morphologic evolution and sedimentary architecture. The directional spread of incoming waves plays a dominant role over fluvial sediment discharge in controlling the width of an active delta lobe, which in turn affects the characteristic rates of delta progradation. Oblique wave approach (and a consequent net alongshore sediment transport) can lead to the development of morphologic asymmetry about the river in a delta's plan-view form. This plan-form asymmetry can include the development of discrete breaks in shoreline orientation and the appearance of self-organized features arising from shoreline instability along the downdrift delta flank, such as spits and migrating shoreline sand waves—features observed on natural deltas. Somewhat surprisingly, waves approaching preferentially from one direction tend to increase sediment deposition updrift of the river. This ‘morphodynamic groin effect’ occurs when the delta's plan-form aspect ratio is sufficiently large such that the orientation of the shoreline on the downdrift flank is rotated past the angle of maximum alongshore sediment transport, resulting in preferential redirection of fluvial sediment updrift of the river mouth.

Ashton, Andrew D.; Giosan, Liviu

2011-07-01

304

Meningiomas of the cerebellopontine angle.  

PubMed

Meningiomas of the cerebellopontine angle (CPA) represent a clinically and surgically interesting entity. The opportunity of complete surgical excision and the incidence of impairment of nerval structures largely depend on the tumour biology that either leads to displacement of surrounding structures by an expansive type of growth or to an enveloping of nerval and vascular structures by an en plaque type of growth. As the origin and the direction of growth are very variable, the exact tumour extension in relation to the nerval structures and the tumour origin can be identified sometimes only at the time of surgery. Out of a series of 230 meningiomas of the posterior skull base operated between 1978 and 1993, data of 134 meningiomas involving the cerebellopontine angle are presented. There were 20% male and 80% female patients, age at the time of surgery ranging from 18 to 76 years, on the average 51 years. The clinical presentation was characterized by a predominant disturbance of the cranial nerves V (19%), VII (11%), VIII (67%) and the caudal cranial nerves (6%) and signs of ataxia (28%). 80% of the meningiomas were larger than 30 mm in diameter, 53% led to evident brainstem compression or dislocation and 85% extended anteriorly to the internal auditory canal. Using the lateral suboccipital approach in the majority of cases and a combined presigmoidal or combined suboccipital and subtemporal approaches in either sequence in 5%, complete tumour removal (Simpson I and II) was accomplished in 95% and subtotal tumour removal in 5%. Histologically the meningiotheliomatous type was most common (49%) followed by the mixed type (19%), fibroblastic (16%), psammomatous (7%), hemangioblastic (7%) and anaplastic (2%) types. Major post-operative complications were CSF leakage (8%) requiring surgical revision in 2% and hemorrhage (3%) requiring revision in 2%. While the majority of neurological disturbances showed signs of recovery, facial nerve paresis or paralysis was encountered in 17%, and facial nerve reconstruction was necessary in 7%. Hearing was preserved in 82% with improvement of hearing in 6%. The variability of tumour extension, the implications and limitations for complete surgical excision are discussed along with the experiences from the literature. PMID:8738504

Matthies, C; Carvalho, G; Tatagiba, M; Lima, M; Samii, M

1996-01-01

305

Angle resolved scatter measurements on optical components  

NASA Astrophysics Data System (ADS)

For precise angle resolved scatter (ARS) investigations on optical components, a scatterometer has been developed, which allows three dimensional scanning of the scattered radiation from the test specimen. By combining the set-up with different radiation sources, measurements in the spectral region from the DUV- to the NIR-spectral range can be performed. The optical properties of the components: reflection, transmittance, and the scatter behavior can be determined in the same run. The measured data are absolutely calibrated to the incident power. In this paper, we report about ARS- measurements on different samples such as holographic gratings, bare and anti reflective coated substrates. Additionally, results of scatter measurements on high reflective mirrors for 633nm with different numbers of layers will be presented. The comparison of the ARS-data and the results of Total Scattering (according to ISO 13696) on the same samples will be discussed.

Kadkhoda, P.; Mädebach, H.; Ristau, D.

2005-10-01

306

Providing solid angle formalism for skyshine calculations.  

PubMed

We detail, derive and correct the technical use of the solid angle variable identified in formal guidance that relates skyshine calculations to dose-equivalent rate. We further recommend it for use with all National Council on Radiation Protection and Measurements (NCRP), Institute of Physics and Engineering in Medicine (IPEM) and similar reports documented. In general, for beams of identical width which have different resulting areas, within ± 1.0 % maximum deviation the analytical pyramidal solution is 1.27 times greater than a misapplied analytical conical solution through all field sizes up to 40 × 40 cm². Therefore, we recommend determining the exact results with the analytical pyramidal solution for square beams and the analytical conical solution for circular beams. PMID:21081888

Gossman, Michael S; Pahikkala, A Jussi; Rising, Mary B; McGinley, Patton H

2010-01-01

307

?-angle monodromy in two dimensions  

NASA Astrophysics Data System (ADS)

“?-angle monodromy” occurs when a theory possesses a landscape of metastable vacua which reshuffle as one shifts a periodic coupling ? by a single period. “Axion monodromy” models arise when this parameter is promoted to a dynamical pseudoscalar field. This paper studies the phenomenon in two-dimensional gauge theories which possess a U(1) factor at low energies: the massive Schwinger and gauged massive Thirring models, the U(N) ’t Hooft model, and the CPN model. In all of these models, the energy dependence of a given metastable false vacuum deviates significantly from quadratic dependence on ? just as the branch becomes completely unstable (distinct from some four-dimensional axion monodromy models). In the Schwinger, Thirring, and ’t Hooft models, the meson masses decrease as a function of ?. In the U(N) models, the landscape is enriched by sectors with non-Abelian ? terms. In the CPN model, we compute the effective action and the size of the mass gap is computed along a metastable branch.

Lawrence, Albion

2012-05-01

308

Angiomas of the cerebellopontine angle.  

PubMed

Angiomas situated within the pontocerebellar cistern lie superficially on the ventrolateral aspect of the brain stem. Occasionally, minor extensions penetrate into the adjacent nervous structures. Five patients bearing such lesions were operated upon, using a microsurgical technique. Radical excision was performed in all cases. Within 2 to 12 months the patients had returned to their previous occupations, being fully able to work or attend school. There is increasing evidence for the effectiveness of surgical treatment of angiomas of the ventrolateral aspect of the brain stem and the cerebellopontine angle. The illness usually presents with hemorrhages of varying severity, ranging from mild to devastating. Impairment of consciousness, contralateral hemiparesis and ipsilateral cranial nerve palsies are the most frequent neurological signs after bleeding. The outcome following excision is primarily related to the preoperative condition. No additional deficits or only minor further impairment can be expected from surgical interference. Exploration is advisable whenever the malformation appears to lie on the surface rather than within the brain stem. PMID:6169805

Viale, G L; Pau, A; Viale, E S; Turtas, S

1981-01-01

309

Influence of Different Diffuser Angle on Sedan's Aerodynamic Characteristics  

NASA Astrophysics Data System (ADS)

The aerodynamic characteristics have a great influence on the fuel economics and the steering stability of a high speed vehicle. The underbody rear diffuser is one of important aerodynamic add-on devices. The parameters of the diffuser, including the diffuser angle, the number and the shape of separators, the shape of the end plate and etc, will affect the underbody flow and the wake. Here, just the influence of the diffuser angle was investigated without separator and the end plate. The method of Computational Fluid Dynamics was adopted to study the aerodynamic characteristics of a simplified sedan with a different diffuser angle respectively. The diffuser angle was set to 0°, 3°, 6°, 9.8° and 12° respectively. The diffuser angle of the original model is 9.8°. The conclusions were drawn that when the diffuser angle increases, the underbody flow and especially the wake change greatly and the pressure change correspondingly; as a result, the total aerodynamic drag coefficients of car first decrease and then increases, while the total aerodynamic lift coefficients decrease.

Hu, Xingjun; Zhang, Rui; Ye, Jian; Yan, Xu; Zhao, Zhiming

310

Reexamination of fault angles predicted by shear localization theory  

SciTech Connect

This paper reexamines orientations of shear bands (fault angles) predicted by a theory of shear localization as a bifurcation from homogeneous deformation. In contrast to the Coulomb prediction, which does not depend on deviatoric stress state, the angle between the band normal and the least (most compressive) principal stress increases as the deviatoric stress state varies from axisymmetric compression to axisymmetric extension. This variation is consistent with the data of Mogi (1967) on Dunham dolomite for axisymmetric compression, extension and biaxial compression, but the predicted angles are generally less than observed. This discrepancy may be due to anisotropy that develops due to crack growth in preferred orientations. Results from specialized constitutive relations for axisymmetric compression and plane strain that include this anisotropy indicate that it tends to increase the predicted angles. Measurements for a weak, porous sandstone (Castlegate) indicate that the band angle decreases with increasing inelastic compaction that accompanies increasing mean stress. This trend is consistent with the predictions of the theory but, for this rock, the observed angles are less than predicted.

Rudnicki, J.W. [Northwestern Univ., Evanston, IL (United States). Dept. of Civil Engineering; Olsson, W.A. [Sandia National Labs., Albuquerque, NM (United States). Geomechanics Dept.

1998-02-01

311

Limbus Impact on Off-angle Iris Degradation  

SciTech Connect

The accuracy of iris recognition depends on the quality of data capture and is negatively affected by several factors such as angle, occlusion, and dilation. Off-angle iris recognition is a new research focus in biometrics that tries to address several issues including corneal refraction, complex 3D iris texture, and blur. In this paper, we present an additional significant challenge that degrades the performance of the off-angle iris recognition systems, called the limbus effect . The limbus is the region at the border of the cornea where the cornea joins the sclera. The limbus is a semitransparent tissue that occludes a side portion of the iris plane. The amount of occluded iris texture on the side nearest the camera increases as the image acquisition angle increases. Without considering the role of the limbus effect, it is difficult to design an accurate off-angle iris recognition system. To the best of our knowledge, this is the first work that investigates the limbus effect in detail from a biometrics perspective. Based on results from real images and simulated experiments with real iris texture, the limbus effect increases the hamming distance score between frontal and off-angle iris images ranging from 0.05 to 0.2 depending upon the limbus height.

Karakaya, Mahmut [ORNL; Barstow, Del R [ORNL; Santos-Villalobos, Hector J [ORNL; Thompson, Joseph W [ORNL; Bolme, David S [ORNL; Boehnen, Chris Bensing [ORNL

2013-01-01

312

Dosimetric Comparison of Manual and Beam Angle Optimization of Gantry Angles in IMRT  

SciTech Connect

Dosimetric comparison of manual beam angle selection (MBS) and beam angle optimization (BAO) for IMRT plans is investigated retrospectively for 15 head and neck and prostate patients. The head and neck and prostate had planning target volumes (PTVs) ranging between 96.0 and 319.9 cm{sup 3} and 153.6 and 321.3 cm{sup 3}, whereas OAR ranged between 8.3 and 47.8 cm{sup 3} and 68.3 and 469.2 cm{sup 3}, respectively. In MBS, a standard coplanar 7-9 fields equally spaced gantry angles were used. In BAO, the selection of gantry angle was optimized by the algorithm for the same number of beams. The optimization and dose-volume constraints were kept the same for both techniques. Treatment planning was performed on the Eclipse treatment planning system. Our results showed that the dose-volume histogram for PTV are nearly identical in both techniques but BAO provided superior sparing of the organs at risk compared with the MBS. Also, MBS produced statistically significant higher monitor units (MU) and segments than the BAO; 13.1 {+-} 6.6% (p = 0.012) and 10.4 {+-} 13.6% (p = 0.140), and 14.6 {+-} 5.6% (p = 1.003E-5) and 12.6 {+-} 7.4% (p = 0.76E-3) for head and neck and prostate cases, respectively. The reduction in MU translates into the reduction in total body and integral dose. It is concluded that BAO provides advantage over MBS for most intenisty-modulated radiation therapy cases.

Srivastava, Shiv P. [Department of Radiation Oncology, Reid Hospital and Health Care Services, Richmond, IN (United States); Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States); Das, Indra J., E-mail: idas@iupui.edu [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States); Kumar, Arvind [Department of Radiation Oncology, Reid Hospital and Health Care Services, Richmond, IN (United States); Johnstone, Peter A.S. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States)

2011-10-01

313

Effects of design parameters of total hip components on the impingement angle and determination of the preferred liner skirt shape with an adequate oscillation angle.  

PubMed

The oscillation angle (OsA), which is the sum of the impingement angles on the two sides when the prosthetic neck sways from the neutral axis of the acetabular cup to the liner rim, is one of the most important factors that can affect the range of motion of an artificial hip joint. The aim of this study was to determine the influence of total hip component design on the impingement angle. Our findings show that an increase in cup depth of the liner restricts the motion of the neck and results in a reduced impingement angle, while an increase in chamfer angle increases the impingement angle until it reaches a critical value when a further increase no longer results in an increase in impingement angle. The impingement angle is not only dependent on the head/neck ratio, but also on the head size itself. For most arbitrarily chosen cup depths and chamfer angles, the neck only impacts at one point on the liner. This study proposes a suitable combination of cup depth and chamfer angle and a preferred impact mode, which, if impingement does occur, enables the neck to impinge on the liner rim over a large area. Cup-neck combinations that have an adequate OsA with maximum femoral head coverage are presented. PMID:23192367

Lin, Hsiao-Che; Chi, Wei-Min; Ho, Ying-Jui; Chen, Jian-Horng

2013-04-01

314

X-31 at High Angle of Attack  

NASA Technical Reports Server (NTRS)

The X-31 aircraft on a research mission from NASA's Dryden Flight Research Center, Edwards, California, is flying nearly perpendicular to the flight path while performing the Herbst maneuver. Effectively using the entire airframe as a speed brake and using the aircrafts unique thrust vectoring system to maintain control, the pilot rapidly rolls the aircraft to reverse the direction of flight, completing the maneuver with acceleration back to high speed in the opposite direction. This type of turning capability could reduce the turning time of a fighter aircraft by 30 percent. The Herbst maneuver was first conducted in an X-31 on April 29, 1993, in the No. 2 X-31 aircraft by German test pilot Karl-Heinz Lang. The X-31 Enhanced Fighter Maneuverability (EFM) demonstrator flew at the Ames- Dryden Flight Research Facility, Edwards, California (redesignated the Dryden Flight Research Center in 1994) from February 1992 until 1995 and before that at the Air Force's Plant 42 in Palmdale, California. The goal of the project was to provide design information for the next generation of highly maneuverable fighter aircraft. This program demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with an advanced flight control system to provide controlled flight to very high angles of attack. The result was a significant advantage over most conventional fighters in close-in combat situations. The X-31 flight program focused on agile flight within the post-stall regime, producing technical data to give aircraft designers a better understanding of aerodynamics, effectiveness of flight controls and thrust vectoring, and airflow phenomena at high angles of attack. Stall is a condition of an airplane or an airfoil in which lift decreases and drag increases due to the separation of airflow. Thrust vectoring compensates for the loss of control through normal aerodynamic surfaces that occurs during a stall. Post-stall refers to flying beyond the normal stall angle of attack, which in the X-31 was at a 30-degree angle of attack. During Dryden flight testing, the X-31 aircraft established several milestones. On November 6, 1992, the X-31 achieved controlled flight at a 70-degree angle of attack. On April 29, 1993, the second X-31 successfully executed a rapid minimum-radius, 180-degree turn using a post-stall maneuver, flying well beyond the aerodynamic limits of any conventional aircraft. This revolutionary maneuver has been called the 'Herbst Maneuver' after Wolfgang Herbst, a German proponent of using post-stall flight in air-to-air combat. It is also called a 'J Turn' when flown to an arbitrary heading change. The aircraft was flown in tactical maneuvers against an F/A-18 and other tactical aircraft as part of the test flight program. During November and December 1993, the X-31 reached a supersonic speed of Mach 1.28. In 1994, the X-31 program installed software to demonstrate quasi-tailless operation. The X-31 flight test program was conducted by an international test organization (ITO) managed by the Advanced Research Projects Office (ARPA), known as the Defense Advanced Research Projects Office (DARPA) before March 1993. The ITO included the U.S. Navy and U.S. Air Force, Rockwell Aerospace, the Federal Republic of Germany, Daimler-Benz (formerly Messerschmitt-Bolkow-Blohm and Deutsche Aerospace), and NASA. Gary Trippensee was the ITO director and NASA Project Manager. Pilots came from participating organizations. The X-31 was 43.33 feet long with a wingspan of 23.83 feet. It was powered by a single General Electric P404-GE-400 turbofan engine that produced 16,000 pounds of thrust in afterburner.

1994-01-01

315

X-31 at High Angle of Attack  

NASA Technical Reports Server (NTRS)

The X-31 aircraft, on a research mission from NASA's Dryden Flight Research Center, Edwards, California, is flying nearly perpendicular to the flight path while performing the Herbst maneuver. Effectively using the entire airframe as a speed brake and using the aircraft's unique thrust vectoring system to maintain control, the pilot rapidly rolls the aircraft to reverse the direction of flight, completing the maneuver with acceleration back to high speed in the opposite direction. This type of turning capability could reduce the turning time of a fighter aircraft by 30 percent. The Herbst maneuver was first conducted in an X-31 on April 29, 1993, in the No. 2 X-31 aircraft by German test pilot Karl-Heinz Lang. The X-31 Enhanced Fighter Maneuverability (EFM) demonstrator flew at the Ames- Dryden Flight Research Facility, Edwards, California (redesignated the Dryden Flight Research Center in 1994) from February 1992 until 1995 and before that at the Air Force's Plant 42 in Palmdale, California. The goal of the project was to provide design information for the next generation of highly maneuverable fighter aircraft. This program demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with an advanced flight control system to provide controlled flight to very high angles of attack. The result was a significant advantage over most conventional fighters in close-in combat situations. The X-31 flight program focused on agile flight within the post-stall regime, producing technical data to give aircraft designers a better understanding of aerodynamics, effectiveness of flight controls and thrust vectoring, and airflow phenomena at high angles of attack. Stall is a condition of an airplane or an airfoil in which lift decreases and drag increases due to the separation of airflow. Thrust vectoring compensates for the loss of control through normal aerodynamic surfaces that occurs during a stall. Post-stall refers to flying beyond the normal stall angle of attack, which in the X-31 was at a 30-degree angle of attack. During Dryden flight testing, the X-31 aircraft established several milestones. On November 6, 1992, the X-31 achieved controlled flight at a 70-degree angle of attack. On April 29, 1993, the second X-31 successfully executed a rapid minimum-radius, 180-degree turn using a post-stall maneuver, flying well beyond the aerodynamic limits of any conventional aircraft. This revolutionary maneuver has been called the 'Herbst Maneuver' after Wolfgang Herbst, a German proponent of using post-stall flight in air-to-air combat. It is also called a 'J Turn' when flown to an arbitrary heading change. The aircraft was flown in tactical maneuvers against an F/A-18 and other tactical aircraft as part of the test flight program. During November and December 1993, the X-31 reached a supersonic speed of Mach 1.28. In 1994, the X-31 program installed software to demonstrate quasi-tailless operation. The X-31 flight test program was conducted by an international test organization (ITO) managed by the Advanced Research Projects Office (ARPA), known as the Defense Advanced Research Projects Office (DARPA) before March 1993. The ITO included the U.S. Navy and U.S. Air Force, Rockwell Aerospace, the Federal Republic of Germany, Daimler-Benz (formerly Messerschmitt-Bolkow-Blohm and Deutsche Aerospace), and NASA. Gary Trippensee was the ITO director and NASA Project Manager. Pilots came from participating organizations. The X-31 was 43.33 feet long with a wingspan of 23.83 feet. It was powered by a single General Electric P404-GE-400 turbofan engine that produced 16,000 pounds of thrust in afterburner.

1994-01-01

316

X-31 at High Angle of Attack  

NASA Technical Reports Server (NTRS)

The X-31 aircraft, on a research mission from NASA's Dryden Flight Research Center, Edwards, California, is flying nearly perpendicular to the flight path while performing the Herbst maneuver. Effectively using the entire airframe as a speed brake and using the aircrafts unique thrust vectoring system to maintain control, the pilot rapidly rolls the aircraft to reverse the direction of flight, completing the maneuver with acceleration back to high speed in the opposite direction. This type of turning capability could reduce the turning time of a fighter aircraft by 30 percent. The Herbst maneuver was first conducted in an X-31 on April 29, 1993, in the No. 2 X-31 aircraft by German test pilot Karl-Heinz Lang. The X-31 Enhanced Fighter Maneuverability (EFM) demonstrator flew at the Ames- Dryden Flight Research Facility, Edwards, California (redesignated the Dryden Flight Research Center in 1994) from February 1992 until 1995 and before that at the Air Force's Plant 42 in Palmdale, California. The goal of the project was to provide design information for the next generation of highly maneuverable fighter aircraft. This program demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with an advanced flight control system to provide controlled flight to very high angles of attack. The result was a significant advantage over most conventional fighters in close-in combat situations. The X-31 flight program focused on agile flight within the post-stall regime, producing technical data to give aircraft designers a better understanding of aerodynamics, effectiveness of flight controls and thrust vectoring, and airflow phenomena at high angles of attack. Stall is a condition of an airplane or an airfoil in which lift decreases and drag increases due to the separation of airflow. Thrust vectoring compensates for the loss of control through normal aerodynamic surfaces that occurs during a stall. Post-stall refers to flying beyond the normal stall angle of attack, which in the X-31 was at a 30-degree angle of attack. During Dryden flight testing, the X-31 aircraft established several milestones. On November 6, 1992, the X-31 achieved controlled flight at a 70-degree angle of attack. On April 29, 1993, the second X-31 successfully executed a rapid minimum-radius, 180-degree turn using a post-stall maneuver, flying well beyond the aerodynamic limits of any conventional aircraft. This revolutionary maneuver has been called the 'Herbst Maneuver' after Wolfgang Herbst, a German proponent of using post-stall flight in air-to-air combat. It is also called a 'J Turn' when flown to an arbitrary heading change. The aircraft was flown in tactical maneuvers against an F/A-18 and other tactical aircraft as part of the test flight program. During November and December 1993, the X-31 reached a supersonic speed of Mach 1.28. In 1994, the X-31 program installed software to demonstrate quasi-tailless operation. The X-31 flight test program was conducted by an international test organization (ITO) managed by the Advanced Research Projects Office (ARPA), known as the Defense Advanced Research Projects Office (DARPA) before March 1993. The ITO included the U.S. Navy and U.S. Air Force, Rockwell Aerospace, the Federal Republic of Germany, Daimler-Benz (formerly Messerschmitt-Bolkow-Blohm and Deutsche Aerospace), and NASA. Gary Trippensee was the ITO director and NASA Project Manager. Pilots came from participating organizations. The X-31 was 43.33 feet long with a wingspan of 23.83 feet. It was powered by a single General Electric P404-GE-400 turbofan engine that produced 16,000 pounds of thrust in afterburner.

1994-01-01

317

A statistical raindrop canting angle model  

NASA Astrophysics Data System (ADS)

A mathematical model to predict accurately the mean and standard deviation of each drop-size canting angle, assuming Gaussian canting angle distributions, is presented. The model utilizes the one-dimensional energy spectrum of horizontal turbulence given by Davenport. By using the differential equation for the horizontal-drop movement, the mean and standard deviation of each drop-size canting angle are calculated. Comparison with Saunders' work shows good agreement.

Howard, J.; Gerogiokas, M.

1982-01-01

318

Results of the Second SeaWiFS Data Analysis Round Robin, March 2000 (DARR-00)  

NASA Technical Reports Server (NTRS)

The accurate determination of upper ocean apparent optical properties (AOPs) is essential for the vicarious calibration of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) instrument and the validation of the derived data products. To evaluate the importance of data analysis methods upon derived AOP values, the Second Data Analysis Round Robin (DARR-00) activity was planned during the latter half of 1999 and executed during March 2000. The focus of the study was the intercomparison of several standard AOP parameters: (1) the upwelled radiance immediately below the sea surface, L(sub u)(0(-),lambda); (2) the downward irradiance immediately below the sea surface, E(sub d)(0(-),lambda); (3) the diffuse attenuation coefficients from the upwelling radiance and the downward irradiance profiles, L(sub L)(lambda) and K(sub d)(lambda), respectively; (4) the incident solar irradiance immediately above the sea surface, E(sub d)(0(+),lambda); (5) the remote sensing reflectance, R(sub rs)(lambda); (6) the normalized water-leaving radiance, [L(sub W)(lambda)](sub N); (7) the upward irradiance immediately below the sea surface, E(sub u)(0(-)), which is used with the upwelled radiance to derive the nadir Q-factor immediately below the sea surface, Q(sub n)(0(-),lambda); and (8) ancillary parameters like the solar zenith angle, theta, and the total chlorophyll concentration, C(sub Ta), derived from the optical data through statistical algorithms. In the results reported here, different methodologies from three research groups were applied to an identical set of 40 multispectral casts in order to evaluate the degree to which differences in data analysis methods influence AOP estimation, and whether any general improvements can be made. The overall results of DARR-00 are presented in Chapter 1 and the individual methods used by the three groups and their data processors are presented in Chapters 2-4.

Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Zibordi, Giuseppe; Berthon, Jean-Francois; D'Alimonte, Davide; Maritorena, Stephane; McLean, Scott; Sildam, Juri; McClain, Charles R. (Technical Monitor)

2001-01-01

319

Miniature Angle Measuring Interferometer (MIAMI)  

NASA Astrophysics Data System (ADS)

The miniature Angle Measuring Interferometer (MIAMI) is a compact laser interferometer that was developed by Ball to satisfy the sensor needs of various pointing and tracking applications. These include: (1) attitude sensing for fast-steering mirrors and other optical elements, (2) structural monitoring and control for optical benches and other structures requiring micro-positioning, and (3) high-precision encoders for use in measuring the angular position of gimballed payloads and drives. MIAMI is constructed from off-the-shelf optical elements, using the inherent precision of the optical faces for alignment when feasible. In the present configuration, the laser light makes eight passes between the sensor head and the retroreflective target, amplifying the sensitivity of this device by a factor of eight. The interference of the two laser beams create fringe patterns, and the separation between fringes is equivalent to one wavelength of laser light (0.6328 micrometers). MIAMI uses interpolation to further subdivide each fringe spacing by a factor of 8 or 16, depending on configuration. MIAMI exhibits excellent performance characteristics, Its angular resolution is 175 nanoradians, and it achieves this with incremental data rates exceeding 5 MHz. MIAMI can accommodate rapid slew rates (greater than 50 deg/sec) and large angular travel (greater than +/- 20 deg). When used as a linear calibration sensor, MIAMI is capable of approxiamtely 10 nanometer linear resolution. The compact design (approximately 5 cubic in.) and light weight (approximately 8 oz) for the sensor head optics make it a very attractive candidate for space sensor applications.

Bauer, Robert J.

320

A comparison of variable angle versus fixed angle distal femoral resection in primary total knee arthroplasty.  

PubMed

This study assessed whether using a variable distal valgus resection angle improved post-operative coronal lower limb alignment in total knee arthroplasty (TKA). Two groups were compared: Fixed (n=124), where a fixed distal valgus resection angle of 7° was used; Variable (n=87), where the resection angle was adjusted to the measured femoral mechanical anatomical (FMA) angle of the patient. FMA and mechanical femoro-tibial (MFT) angles were measured on pre-operative and post-operative hip-knee-ankle radiographs. 85% of patients in the Variable group had a post-operative MFT angle within 0°±3°compared to 69% in the Fixed group (P=0.006). The use of a fixed distal femoral resection angle for all patients is not appropriate. Setting the resection to an individual patient's FMA angle can significantly improve the post-operative MFT angle. PMID:24355255

Deakin, Angela H; Sarungi, Martin

2014-06-01

321

Best Angle to Orient Two Intersecting Lines  

SciTech Connect

Fiducials in the form of intersecting straight lines are used to align the target in the final target chamber of the National Ignition Facility of Lawrence Livermore National Laboratory. One of the techniques used to locate these lines is the Hough transform. When two lines intersect at a 90 degree angle, it is tempting to orient the lines to horizontal and vertical directions. There are other possible angles at which the lines may be oriented. One question that arises while designing the fiducials is whether there is a preferred angle or range of angles that leads to higher accuracy. This work attempts to answer this question through detailed computer simulation.

Awwal, A S; Ferguson, S W; Shull, P B

2006-07-25

322

Pitch Angle of Galactic Spiral Arms  

NASA Astrophysics Data System (ADS)

One of the key parameters that characterizes spiral arms in disk galaxies is a pitch angle that measures the inclination of a spiral arm to the direction of galactic rotation. The pitch angle differs from galaxy to galaxy, which suggests that the rotation law of galactic disks determines it. In order to investigate the relation between the pitch angle of spiral arms and the shear rate of galactic differential rotation, we perform local N-body simulations of pure stellar disks. We find that the pitch angle increases with the epicycle frequency and decreases with the shear rate and obtain the fitting formula. This dependence is explained by the swing amplification mechanism.

Michikoshi, Shugo; Kokubo, Eiichiro

2014-06-01

323

Analyzing angle crashes at unsignalized intersections using machine learning techniques.  

PubMed

A recently developed machine learning technique, multivariate adaptive regression splines (MARS), is introduced in this study to predict vehicles' angle crashes. MARS has a promising prediction power, and does not suffer from interpretation complexity. Negative Binomial (NB) and MARS models were fitted and compared using extensive data collected on unsignalized intersections in Florida. Two models were estimated for angle crash frequency at 3- and 4-legged unsignalized intersections. Treating crash frequency as a continuous response variable for fitting a MARS model was also examined by considering the natural logarithm of the crash frequency. Finally, combining MARS with another machine learning technique (random forest) was explored and discussed. The fitted NB angle crash models showed several significant factors that contribute to angle crash occurrence at unsignalized intersections such as, traffic volume on the major road, the upstream distance to the nearest signalized intersection, the distance between successive unsignalized intersections, median type on the major approach, percentage of trucks on the major approach, size of the intersection and the geographic location within the state. Based on the mean square prediction error (MSPE) assessment criterion, MARS outperformed the corresponding NB models. Also, using MARS for predicting continuous response variables yielded more favorable results than predicting discrete response variables. The generated MARS models showed the most promising results after screening the covariates using random forest. Based on the results of this study, MARS is recommended as an efficient technique for predicting crashes at unsignalized intersections (angle crashes in this study). PMID:21094345

Abdel-Aty, Mohamed; Haleem, Kirolos

2011-01-01

324

Foreign Body Embedded in Anterior Chamber Angle  

PubMed Central

Introduction. We present a case of a metallic foreign body embedded in the anterior chamber angle. After standing in close proximity to a construction worker breaking a tile, a 26-year-old woman using soft contact lens for the correction of mild myopia presented to emergency department for evaluation of a foreign body sensation of her right eye. Methods and Results. Diagnosis was confirmed by gonioscopic examination and a noncontrast CT scan of head and orbits. The foreign body was removed by an external approach without utilizing a magnet. The patient's final outcome was favorable. Discussion. The above is a rare clinical situation, which is impossible to detect on slit-lamp examination without a gonioscopic view. Proper imaging and a specific management are mandatory in order to achieve favorable outcome.

Graffi, Shmuel; Tiosano, Beatrice; Ben Cnaan, Ran; Bahir, Jonathan; Naftali, Modi

2012-01-01

325

Foreign body embedded in anterior chamber angle.  

PubMed

Introduction. We present a case of a metallic foreign body embedded in the anterior chamber angle. After standing in close proximity to a construction worker breaking a tile, a 26-year-old woman using soft contact lens for the correction of mild myopia presented to emergency department for evaluation of a foreign body sensation of her right eye. Methods and Results. Diagnosis was confirmed by gonioscopic examination and a noncontrast CT scan of head and orbits. The foreign body was removed by an external approach without utilizing a magnet. The patient's final outcome was favorable. Discussion. The above is a rare clinical situation, which is impossible to detect on slit-lamp examination without a gonioscopic view. Proper imaging and a specific management are mandatory in order to achieve favorable outcome. PMID:23091762

Graffi, Shmuel; Tiosano, Beatrice; Ben Cnaan, Ran; Bahir, Jonathan; Naftali, Modi

2012-01-01

326

A superconducting large-angle magnetic suspension  

NASA Technical Reports Server (NTRS)

SatCon Technology Corporation has completed a Small Business Innovation Research (SBIR) Phase 2 program to develop a Superconducting Large-Angle Magnetic Suspension (LAMS) for the NASA Langley Research Center. The Superconducting LAMS was a hardware demonstration of the control technology required to develop an advanced momentum exchange effector. The Phase 2 research was directed toward the demonstration for the key technology required for the advanced concept CMG, the controller. The Phase 2 hardware consists of a superconducting solenoid ('source coils') suspended within an array of nonsuperconducting coils ('control coils'), a five-degree-of-freedom positioning sensing system, switching power amplifiers, and a digital control system. The results demonstrated the feasibility of suspending the source coil. Gimballing (pointing the axis of the source coil) was demonstrated over a limited range. With further development of the rotation sensing system, enhanced angular freedom should be possible.

Downer, James R.; Anastas, George V., Jr.; Bushko, Dariusz A.; Flynn, Frederick J.; Goldie, James H.; Gondhalekar, Vijay; Hawkey, Timothy J.; Hockney, Richard L.; Torti, Richard P.

1992-01-01

327

Cerebellopontine angle lipoma with extracranial extension.  

PubMed

Lipomas of the cerebellopontine angle (CPA) are rare. A recent literature review identified only 98 reported cases of CPA lipoma. We present here a case of CPA lipoma in a 28-year-old woman who was admitted to our hospital with hearing loss in her left ear. Computed tomography scan and magnetic resonance imaging revealed a CPA mass lesion with extracranial extension around the left internal carotiol artery. The patient was operated on in the sitting position via a right suboccipital craniectomy. The intracranial part of the mass was partially removed. Histopathological examination resulted in a diagnosis of lipoma. Surgical treatment of CPA lipomas is rarely indicated, and the aim of surgery must be decompression of neural structures. PMID:17113988

Iplikcioglu, Celal; Bikmaz, Kerem; Gokduman, Cem A; Bek, Sirzat

2006-12-01

328

Reconnection voltage as a function of IMF clock angle  

NASA Technical Reports Server (NTRS)

Magnetic reconnection between the IMF and the geomagnetic field is thought to play a major role in the transfer of solar wind momentum and energy to the magnetosphere. Both analytic modeling and analysis of geophysical data have shown that this coupling process should be a sensitive function of the clock angle of the IMF. Results are presented from a three-dimensional, MHD, global numerical simulation code for the reconnection voltage between the closed geomagnetic field and the IMF as a function of the IMF clock angle. These results are consistent with a sin(theta/2) functional behavior.

Fedder, J. A.; Mobarry, C. M.; Lyon, J. G.

1991-01-01

329

Correlation analysis of the beam angle dependence for elastography  

PubMed Central

Signal decorrelation is a major source of error in the displacements estimated using correlation techniques for elastographic imaging. Previous papers have addressed the variation in the correlation coefficient as a function of the applied compression for a finite window size and an insonification angle of zero degrees. The recent use of angular beam-steered radio-frequency echo signals for spatial angular compounding and shear strain estimation have demonstrated the need for understanding signal decorrelation artifacts for data acquired at different beam angles. In this paper, we provide both numerical and closed form theoretical solutions of the correlation between pre- and post-compression radio-frequency echo signals acquired at a specified beam angle. The expression for the correlation coefficient obtained is a function of the beam angle and the applied compression for a finite duration window. Accuracy of the theoretical results is verified using tissue-mimicking phantom experiments on a uniformly elastic phantom using beam-steered data acquisitions on a linear array transducer. The theory predicts a faster decorrelation with changes in the beam or insonification angle for longer radio-frequency echo signal segments and at deeper locations in the medium. Theoretical results provide useful information for improving angular compounding and shear strain estimation techniques for elastography.

Rao, Min; Varghese, Tomy

2006-01-01

330

Exact Interior Reconstruction from Truncated Limited-Angle Projection Data  

PubMed Central

Using filtered backprojection (FBP) and an analytic continuation approach, we prove that exact interior reconstruction is possible and unique from truncated limited-angle projection data, if we assume a prior knowledge on a subregion or subvolume within an object to be reconstructed. Our results show that (i) the interior region-of-interest (ROI) problem and interior volume-of-interest (VOI) problem can be exactly reconstructed from a limited-angle scan of the ROI/VOI and a 180 degree PI-scan of the subregion or subvolume and (ii) the whole object function can be exactly reconstructed from nontruncated projections from a limited-angle scan. These results improve the classical theory of Hamaker et al. (1980).

Ye, Yangbo; Yu, Hengyong; Wang, Ge

2008-01-01

331

Structure Inclination Angles in the Convective Atmospheric Surface Layer  

NASA Astrophysics Data System (ADS)

Two-point correlations of the fluctuating streamwise velocity are examined in the atmospheric surface layer over the salt flats of Utah's western desert, and corresponding structure inclination angles are obtained for neutral, stable and unstable conditions. The neutral surface-layer results supplement evidence for the invariance of the inclination angle given in Marusic and Heuer (Phys Rev Lett 99:114504, 2007). In an extension of those results it is found that the inclination angle changes drastically under different stability conditions in the surface layer, varying systematically with the Monin-Obukhov stability parameter in the unstable regime. The variation is parametrized and subsequently can be used to improve existing near-wall models in the large-eddy simulation of the atmospheric surface layer.

Chauhan, Kapil; Hutchins, Nicholas; Monty, Jason; Marusic, Ivan

2013-04-01

332

A Climbing Class' Reinvention of Angles  

ERIC Educational Resources Information Center

A previous study shows how a twelve-year-old girl discovers angles in her narrative from a climbing trip. Based on this research, the girl's class takes part in one day of climbing and half a day of follow-up work at school. The students mathematise their climbing with respect to angles and they express themselves in texts and drawings. Their…

Fyhn, Anne Birgitte

2008-01-01

333

Classification procedure in limited angle tomography system  

SciTech Connect

In this work we propose the use of limited angle reconstruction algorithms combined with a procedure for defect detection and feature evaluation in three dimensions. The procedure consists of the following steps: acquisition of the X-ray projections, approximated limited angle 3D image reconstruction, and image preprocessing and classification.

Chlewicki, W.; Baniukiewicz, P.; Chady, T.; Brykalski, A. [Faculty of Electrical Engineering, Westpomeranian University of Technology, Szczecin (Poland)

2011-06-23

334

SNAKE. A Solid Angle Calculational System  

SciTech Connect

SNAKE calculates solid angles subtended by geometric forms composed of spherical, cylindrical, and planar surfaces, either singularly or in specified arrays, from exact analytic integral forms. Thus, it is capable of providing information necessary for the solid angle method for evaluation of neutron interaction in arrays.

Thompson, J.K.; Lewallen, M.A.; Trapp, J.T. [Pacific Northwest Lab., Richland, WA (United States)

1984-03-01

335

Monte Carlo backbone sampling for polypeptides with variable bond angles and dihedral angles using concerted rotations and a Gaussian bias  

NASA Astrophysics Data System (ADS)

An efficient concerted rotation algorithm for use in Monte Carlo statistical mechanics simulations of polypeptides is reported that includes flexible bond and dihedral angles. A Gaussian bias is applied with driver bond and dihedral angles to optimize the sampling efficiency. Jacobian weighting is required in the Metropolis test to correct for imbalances in resultant transition probabilities. Testing of the methodology includes Monte Carlo simulations for polyalanines with 8-14 residues and a 36-residue protein as well as a search to find the lowest-energy conformer of the pentapeptide Met-enkephalin. The results demonstrate the formal correctness and efficiency of the method.

Ulmschneider, Jakob P.; Jorgensen, William L.

2003-03-01

336

GR Schwarzschild Light Launch Angle Program  

NSDL National Science Digital Library

The GR Schwarzschild Light Launch Angle program simulates the path of light around a black hole using the Schwarzschild metric and allows the user to set the launch angle of the light. It also displays a plot of the effective potential well for the light. The default setting is light with an r-coordinate value of 3.5 and a launch angle of 1.571 (in radians). GR Schwarzschild Light Launch Angle Parameter is part of a suite of Open Source Physics programs that model aspects of General Relativity. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the gr_schwarzschild_light_launch_angle.jar file will run the program if Java is installed. Other programs provide additional visualizations. They can be found by searching ComPADRE for Open Source Physics, OSP, or General Relativity.

Christian, Wolfgang; Belloni, Mario; Cox, Anne

2008-05-27

337

Low Angle Extensional Faults in a Thrusting/Compressive Regime  

NASA Astrophysics Data System (ADS)

Contractional architecture within the compressive edges of mountain belts is dominated by thrust faulting. Thrust faults of regional extent produce the emplacement of thrust nappes along low angle faults spanning for of kilometres. The erosion, and related removal, of connecting portions of a nappe may isolate remnant portions of the nappe, or klippen. The process results in exotic rock blocks of different sizes resting on the hanging wall of low angle faults. This simple structural architecture may be misinterpreted because as the result of a more complex deformation history. Studying the meaning of exotic rock blocks along a thrust fault of regional extent in the Southern Apennines, Italy, we show that previously interpreted thrust-related klippe are the products of a subsequent deformation stage overprinting the thrust features. A suite of low angle, foreland direct, brittle faults developed during the younger deformation stage were recognised in the studied exotic rock blocks. Low angle faults merge at the basal tectonic contacts of the rock blocks, and truncate thrust-related structures in the footwalls. The low angle faults cut down-section into the footwalls, and appear extensional. The meaning of the low-angle extensional faults is discussed in the framework of the transition tectonics from syn-orogenic contraction to late/post orogenic extension, accompanied in the Southern Apennines by intense uplift. We interpret the extensional tectonic fabrics as the products of a heterogeneous deformation resulting in progressive tilting of weak interfaces. In the structures, gravity sliding processes can induce normal faulting compatible with a thrust regime. The findings has implications for the reconstruction of the history of deformation of a large sector of the Southern Apennines, Italy.

Bucci, F.; Novellino, R.; Adurno, I.; Gueguen, E.; Guzzetti, F.; Cardinali, M.; Tavarnelli, E.; Guglielmi, P.; Prosser, G.

2012-04-01

338

Associations between Narrow Angle and Adult Anthropometry: The Liwan Eye Study.  

PubMed

Abstract Purpose: To assess the associations between narrow angle and adult anthropometry. Methods: Chinese adults aged 50 years and older were recruited from a population-based survey in the Liwan District of Guangzhou, China. Narrow angle was defined as the posterior trabecular meshwork not visible under static gonioscopy in at least three quadrants (i.e. a circumference of at least 270°). Logistic regression models were used to examine the associations between narrow angle and anthropomorphic measures (height, weight and body mass index, BMI). Results: Among the 912 participants, lower weight, shorter height, and lower BMI were significantly associated with narrower angle width (tests for trend: mean angle width in degrees vs weight p?angle. The crude association between height and narrow angle was largely attributable to a stronger association with age and sex. Lower BMI and weight remained significantly associated with narrow angle after adjustment for height, age, sex, axial ocular biometric measures and education. In analyses stratified by sex, the association between BMI and narrow angle was only observed in women. Conclusion: Lower BMI and weight were associated with significantly greater odds of narrow angle after adjusting for age, education, axial ocular biometric measures and height. The odds of narrow angle increased 7% per 1 unit decrease in BMI. This association was most evident in women. PMID:24707840

Jiang, Yuzhen; He, Mingguang; Friedman, David S; Khawaja, Anthony P; Lee, Pak Sang; Nolan, Winifred P; Yin, Qiuxia; Foster, Paul J

2014-06-01

339

The variational assimilation experiment of GPS bending angle  

NASA Astrophysics Data System (ADS)

More and more new types of observational data provide many new opportunities for improving numerical weather forecasts. Among these, the GPS (Global Positioning System) bending angle is undoubtedly very important. There are many advantages of the GPS bending angle, such as high resolution, availability in all weather conditions, and global data coverage. Thus it is very valuable to assimilate GPS bending angle data into numerical weather models. This paper introduces how to obtain and assimilate the GPS bending angle. There are two methods of assimilation: the indirect method and direct method, and they are both introduced in this paper. During the minimizing process of variational assimilation, calculation efficiency is very important and the optimal step size greatly influences the algorithm efficiency. Based on the characteristics of the minimizing algorithm, we obtain an adaptive method for calculating the optimizing step suitable for all kinds of minimization algorithms through mathematical deduction. Finally, a numerical variational assimilation experiment is performed using the GPS bending angle data of 11 October 1995. The numerical results indicate the validity of the variational assimilation method and the adaptive method introduced here.

Wang, Yunfeng; Wang, Bin

2003-05-01

340

Non-Contact Ultrasonic Characterization of Angled Surface Defects  

NASA Astrophysics Data System (ADS)

Surface ultrasonic waves have been shown to have many uses in non-destructive testing, in particular for gauging the depth of surface defects. Much of the previous work has assumed that these defects are oriented normal to the surface. However, this is not always the case; for example, rolling contact fatigue in rails propagates at an angle of around 25° to the surface, and this angle may affect the characterisation. We present results using non-contact ultrasonic methods to generate and detect ultrasound on samples with a range of defect angles, and compare these with finite element method (FEM) models. We use both electromagnetic acoustic transducers (EMATs) and laser ultrasound. The depth calibration when measuring ultrasound transmission is considered, and what affect the angle of a defect has. Several other methods of characterising crack depth and angle are also discussed, including the arrival times of reflected and mode-converted waves, the delay in the transmission of the high-frequency Rayleigh wave, and the enhancement of the signal at the defect in both the in-plane and out-of-plane components.

Edwards, R. S.; Dutton, B.; Rosli, M. H.; Clough, A. R.

2011-06-01

341

Trim angle measurements in free-flight facilities  

NASA Technical Reports Server (NTRS)

The aerodynamic cofficients and trim angle for an aerobrake at Mach 9.2 and 11.8 were found using a combination of experiment and computation. Free-flight tests were performed at NASA Ames Research Center's Hypervelocity Free-Flight Aerodynamic Facility, and the forebody pressure distribution was calculated using a three-dimensional Navier-Stokes code with an effective specific heat ratio. Using the computed drag, lift, and moments to prescribe the number of terms in the aerodynamic coefficient expansions and to specify the values of the higher order terms, the experimental aerodynamic coefficients and trim angle were found using a six-degree-of-freedom, weighted, least-squares analysis. The experimental and computed aerodynamic coefficients and trim angles are in good agreement. The trim angle obtained from the free-flight tests, 14.7 deg, differs from the design trim angle, 17 deg, and from the Langley wind tunnel results, 12 deg in air and 17 deg in CF4. These differences are attributable to real-gas effects.

Yates, Leslie A.; Venkatapathy, Ethiraj

1991-01-01

342

The Influence of Dynamic Contact Angle on Wetting Dynamics  

NASA Technical Reports Server (NTRS)

When surface tension forces dominate, and regardless of whether the situation is static or dynamic, the contact angle (the angle the interface between two immiscible fluids makes when it contacts a solid) is the key parameter that determines the shape of a fluid-fluid interface. The static contact angle is easy to measure and implement in models predicting static capillary surface shapes and such associated quantities as pressure drops. By contrast, when the interface moves relative to the solid (as in dynamic wetting processes) the dynamic contact angle is not identified unambiguously because it depends on the geometry of the system Consequently, its determination becomes problematic and measurements in one geometry cannot be applied in another for prediction purposes. However, knowing how to measure and use the dynamic contact angle is crucial to determine such dynamics as a microsystem throughput reliably. In this talk we will present experimental and analytical efforts aimed at resolving modeling issues present in dynamic wetting. We will review experiments that show the inadequacy of the usual hydrodynamic model when a fluid-fluid meniscus moves over a solid surface such as the wall of a small tube or duct. We will then present analytical results that show how to parametrize these problems in a predictive manner. We will illustrate these ideas by showing how to implement the method in numerical fluid mechanical calculations.

Rame, Enrique; Garoff, Steven

2005-01-01

343

Demonstration of Angle-Dependent Casimir Force between Corrugations  

NASA Astrophysics Data System (ADS)

The normal Casimir force between a sinusoidally corrugated gold coated plate and a sphere was measured at various angles between the corrugations using an atomic force microscope. A strong dependence on the orientation angle of the corrugation is found. The measured forces were found to deviate from the proximity force approximation and are in agreement with the theory based on the gradient expansion including correlation effects of geometry and material properties. We analyze the role of temperature. The obtained results open new opportunities for control of the Casimir effect in micromechanical systems.

Banishev, A. A.; Wagner, J.; Emig, T.; Zandi, R.; Mohideen, U.

2013-06-01

344

Demonstration of angle-dependent Casimir force between corrugations.  

PubMed

The normal Casimir force between a sinusoidally corrugated gold coated plate and a sphere was measured at various angles between the corrugations using an atomic force microscope. A strong dependence on the orientation angle of the corrugation is found. The measured forces were found to deviate from the proximity force approximation and are in agreement with the theory based on the gradient expansion including correlation effects of geometry and material properties. We analyze the role of temperature. The obtained results open new opportunities for control of the Casimir effect in micromechanical systems. PMID:23829717

Banishev, A A; Wagner, J; Emig, T; Zandi, R; Mohideen, U

2013-06-21

345

Magic Angles and Cross-Hatching Instability in Hydrogel Fracture  

NASA Astrophysics Data System (ADS)

The full 2D analysis of roughness profiles of fracture surfaces resulting from quasistatic crack propagation in gelatin gels reveals an original behavior characterized by (i) strong anisotropy with maximum roughness at V-independent symmetry-preserving angles and (ii) a subcritical instability leading, below a critical velocity, to a cross-hatched regime due to straight macrosteps drifting at the same magic angles and nucleated on crack-pinning network inhomogeneities. Step height values are determined by the width of the strain-hardened zone, governed by the elastic crack blunting characteristic of soft solids with breaking stresses much larger than low strain moduli.

Baumberger, T.; Caroli, C.; Martina, D.; Ronsin, O.

2008-05-01

346

Angle-of-attack estimation for analysis of CAT encounters  

NASA Technical Reports Server (NTRS)

Recent studies of clear-air turbulence (CAT) encounters involving wide-body airliners have been based upon flight-path wind estimates made by analyzing digital flight-data-recorder (DFDR) records and radar records. Such estimates require a time history of the aircraft angle of attack, a record that is not usually included in the DFDR measurement set. This paper describes a method for reconstructing angle of attack that utilizes available flight record and aircraft-specific information associated with an aerodynamic model of the lift coefficient. Results from two wide-body incidents in which vane measurements of angle of attack were recorded show good agreement between measured and calculated time histories. This research has been performed in cooperation with the National Transportation Safety Board to provide a better understanding of the CAT phenomenon.

Bach, R. E., Jr.; Parks, E. K.

1985-01-01

347

Wide-angle Michelson interferometer based on LCoS  

NASA Astrophysics Data System (ADS)

A wide-angle Michelson interferometer based on LCoS is proposed as a novel device with no moving part for effectively measuring the upper atmospheric temperature and wind. The testing experiment gives a sequence of interferograms which can be used for evaluating the performances of this device through an image processing. The maximum phase modulations of 2.13? and 1.58? for 532 nm and 633 nm respectively can cover the desired detection range. The OPD variations with regard to incident angle are within 0.59 wavelengths. The instrument visibilities of 0.226-0.146 for both wavelengths have the decreasing trends with regard to the increasing incident angles. The suggestions for improving performances are also given. The results have proved its effectiveness which can satisfy the requirements for atmospheric wind measurement.

Gao, Haiyang; Hua, Dengxin; Tang, Yuanhe; Cao, Xiangang; Liu, Hanchen; Jia, Wanli

2013-04-01

348

Orientation angle and the adhesion of single gecko setae  

PubMed Central

We investigated the effects of orientation angle on the adhesion of single gecko setae using dual-axis microelectromechanical systems force sensors to simultaneously detect normal and shear force components. Adhesion was highly sensitive to the pitch angle between the substrate and the seta's stalk. Maximum lateral adhesive force was observed with the stalk parallel to the substrate, and adhesion decreased smoothly with increasing pitch. The roll orientation angle only needed to be roughly correct with the spatular tuft of the seta oriented grossly towards the substrate for high adhesion. Also, detailed measurements were made to control for the effect of normal preload forces. Higher normal preload forces caused modest enhancement of the observed lateral adhesive force, provided that adequate contact was made between the seta and the substrate. These results should be useful in the design and manufacture of gecko-inspired synthetic adhesives with anisotropic properties, an area of substantial recent research efforts.

Hill, Ginel C.; Soto, Daniel R.; Peattie, Anne M.; Full, Robert J.; Kenny, T. W.

2011-01-01

349

Measuring Non-spherical Airborne Dust with Space-based MISR Multi-angle Imaging.  

NASA Astrophysics Data System (ADS)

Some of the world's largest dust plumes emanate from Northern Eurasian deserts and are expected to increasingly affect Asian ergonomics. Together with field experiments, satellite observations of dust outbreaks, placed into the context of large-scale dust transport modeling, can help understand the impact of mineral dust aerosols on past and present climate and climate predictions in North and Central Asia. Multi-angle instruments such as the Multi-angle Imaging SpectroRadiometer (MISR) provide independent constraints on aerosol properties based on sensitivity to the shape of the scattering phase function. We present an analysis of the Multi-angle Imaging SpectroRadiometer (MISR) Standard Aerosol Retrieval algorithm, updated with new non-spherical dust models (Version 16 and higher). We compare the MISR products with coincident AERONET surface sun-photometer observations taken during the passage of dust fronts. Our analysis shows that during such events MISR retrieves Angstrom exponents characteristic of large particles, having little spectral variation in extinction over the MISR wavelength range (442, 550, 672 and 866 nm channels), as expected. Also, the retrieved fraction of non-spherical particles is very high. This quantity is not retrieved by satellite instruments having only nadir-viewing cameras. We assess whether MISR aerosol optical thickness (AOT) acquired at about 10:30 AM local time, can be used to represent daily mean AOT in dust climate forcing studies, by comparing MISR-retrieved aerosol optical thickness (AOT) with AERONET daily-mean values. We also compare the effect of particle shape on MISR and MODIS dust retrievals, using co-located MISR, MODIS, and AERONET AOTs and Angstrom exponents. In most cases obtained for this study, MODIS had no retrievals due to sun-glint when MISR's narrower swath observed AERONET sties on islands surrounded by dark water. For the few coincident MISR-MODIS-AERONET dark-water, dusty condition retrievals we obtained, the MISR retrievals were in better agreement with AERONET than those from MODIS. Over bright desert sites, MODIS AOTs at visible wavelengths was systematically higher than those of AERONET and MISR. MISR-derived aerosol type mixtures for these cases included non-spherical dust components with high frequency in retrievals over dark water, and slightly lower frequency over land. The frequency with which non-spherical dust models were selected by the algorithm also decreased in dusty regions affected by pollution. Both MISR and MODIS retrievals have a high fail rate over optically thick dust plumes.

Kalashnikova, O. V.; Diner, D. J.; Abdou, W.; Kahn, R.; Gaitley, B. J.; Gasso, S.

2004-12-01

350

[Functional stability of Champy miniplate osteosynthesis in mandibular angle fractures].  

PubMed

This paper presents the results of the treatment of fractures of the mandibular angle using miniplate osteosynthesis. From 1984 to 1993 347 patients with 358 fractures were operated in the department of Maxillofacial Surgery at the University of Cologne. In all cases total bone healing could be observed while complications were rare. PMID:8755411

Pape, H D; Schippers, C G; Gerlach, K L; Walz, C

1996-01-01

351

Unambiguous Accuracy of an Interferometer Angle-Measuring System  

Microsoft Academic Search

In this paper we consider the problem of using signals received at three or four antennas to estimate the direction from which radio-frequency (RF) radiation is arriving. Though the results are couched in the terminology of angle measurements, they are applicable to any ambiguous measurements for which the number of ambiguities is inversely proportional to the accuracy. For an interferometric

William B. Kendall

1965-01-01

352

Small angle neutron scattering from nanometer grain sized materials  

SciTech Connect

Small angie neutron scattering has been utilized, along with a number of complementary characterization methods suitable to the nanometer size scale, to investigate the structures of cluster-assembled nanophase materials. Results of these investigations are described and problems and opportunities in using small angle scattering for elucidating nanostructures are discussed.

Epperson, J.E.; Siegel, R.W.

1991-11-01

353

Exploring Dissections of Rectangles into Right-Angled Triangles  

ERIC Educational Resources Information Center

In this article we highlight how a simple classroom activity associated with the dissection of rectangles into right-angled triangles can lead on to a number of interesting explorations for students following a post-16 mathematics course. Several results connected with this construction are obtained, and some of the educational benefits of…

Griffiths, Martin

2013-01-01

354

Analysis and design of wide-angle foveated optical systems  

NASA Astrophysics Data System (ADS)

The development of compact imaging systems capable of transmitting high-resolution images in real-time while covering a wide field-of-view (FOV) is critical in a variety of military and civilian applications: surveillance, threat detection, target acquisition, tracking, remote operation of unmanned vehicles, etc. Recently, optical foveated imaging using liquid crystal (LC) spatial light modulators (SLM) has received considerable attention as a potential approach to reducing size and complexity in fast wide-angle lenses. The fundamental concept behind optical foveated imaging is reducing the number of elements in a fast wide-angle lens by placing a phase SLM at the pupil stop to dynamically compensate aberrations left uncorrected by the optical design. In the recent years, considerable research and development has been conducted in the field of optical foveated imaging based on the LC SLM technology, and several foveated optical systems (FOS) prototypes have been built. However, most research has been focused so far on the experimental demonstration of the basic concept using off-the-shelf components, without much concern for the practicality or the optical performance of the systems. Published results quantify only the aberration correction capabilities of the FOS, often claiming diffraction-limited performance at the region of interest (ROI). However, these results have continually overlooked diffraction effects on the zero-order efficiency and the image quality. The research work presented in this dissertation covers the methods and results of a detailed theoretical research study on the diffraction analysis, image quality, design, and optimization of fast wide-angle FOSs based on the current transmissive LC SLM technology. The amplitude and phase diffraction effects caused by the pixelated aperture of the SLM are explained and quantified, revealing fundamental limitations imposed by the current transmissive LC SLM technology. As a part of this study, five different fast wide-angle lens designs that can be used to build practical FOSs were developed, revealing additional challenges specific to the optical design of fast wide-angle systems, such as controlling the relative illumination, distortion, and distribution of aberrations across a wide FOV. One of the lens design examples was chosen as a study case to demonstrate the design, analysis, and optimization of a practical wide-angle FOS based on the current state-of-the-art transmissive LC SLM technology. The effects of fabrication and assembly tolerances on the image quality of fast wide-angle FOSs were also investigated, revealing the sensitivity of these fast well-corrected optical systems to manufacturing errors. The theoretical study presented in this dissertation sets fundamental analysis, design, and optimization guidelines for future developments in fast wide-angle FOSs based on transmissive SLM devices.

Curatu, George

355

Multispectral limited-angle image reconstruction  

SciTech Connect

Limited-angle reconstruction algorithms utilize a priori information on the objects to compensate for the missing scannings in limited-angle imagings. In earlier paper,s we have shown qualitatively that decomposing a composite object through multiple energy scans enables better use of the a priori information and therefore is capable of bringing about improvement in limited-angle reconstructions. In this paper, a more quantitative analysis is performed to study the conditions for such a improvement and its magnitude. In particular, it is shown that this technique favors reconstruction for the hot spot type of phantoms much more than the cold spot type.

Tam, K.C.

1983-02-01

356

Angle-resolved coherent optical wave mixing  

SciTech Connect

A generalized approach is derived for the analysis of angle-resolved coherent optical wave mixing. Remarkably with this, a signal is calculated to remain efficiently generated for the arbitrary evolution of a quantum superposition state and for energy transfer spanning an ultrawide bandwidth in solution. This approach is compact and applies across matter processes and wave-mixing schemes. A high sensitivity and sampling rate are shown to be intrinsic to angle-resolved wave mixing and an angle-resolved six-wave mixing scheme is proposed for the mapping of molecular structure.

Mercer, Ian P. [School of Physics, Centre for Synthesis and Chemical Biology, University College Dublin, Dublin 4 (Ireland)

2010-10-15

357

Impact angles as an alternative way to improve aerosolisation of powders for inhalation?  

PubMed

This study aims to investigate the role of impact angles on the de-agglomeration performance of powders for inhalation. Agglomerates of a model drug mannitol were impacted at customized impaction throats containing two angles (15-75 degrees and 45-45 degrees) or a single angle (15 degrees, 45 degrees and 90 degrees) using various air flow rates. The mass fraction of fine particles <5microm in the aerosol (FPF(Loaded)) was measured by a liquid impinger coupled to a laser diffractometer. Results showed that for the two-angle throats, there existed an optimal angle (45 degrees) and air flow (120lmin(-1)) for the FPF(Loaded), resulting from a balance between improved de-agglomeration and enhanced throat deposition with increasing air flow. When the throat contained two equal angles of 45 degrees , most powder deposition occurred at the first angle, indicating that the first angle was likely to cause major de-agglomeration, while the second angle might act as a facilitator for further break-up, but the deposition was minimum as the fragment sizes and velocity at the second impaction were smaller. This hypothesis was supported by further studies using single-angle throats and numerical simulation (DEM-CFD). These findings imply the potential importance of using angular design features for multiple impactions to improve DPI performance. PMID:20615465

Adi, Santoso; Tong, Zhenbo; Chan, Hak-Kim; Yang, Runyu; Yu, Aibing

2010-10-01

358

Rubber hand illusion affects joint angle perception.  

PubMed

The Rubber Hand Illusion (RHI) is a well-established experimental paradigm. It has been shown that the RHI can affect hand location estimates, arm and hand motion towards goals, the subjective visual appearance of the own hand, and the feeling of body ownership. Several studies also indicate that the peri-hand space is partially remapped around the rubber hand. Nonetheless, the question remains if and to what extent the RHI can affect the perception of other body parts. In this study we ask if the RHI can alter the perception of the elbow joint. Participants had to adjust an angular representation on a screen according to their proprioceptive perception of their own elbow joint angle. The results show that the RHI does indeed alter the elbow joint estimation, increasing the agreement with the position and orientation of the artificial hand. Thus, the results show that the brain does not only adjust the perception of the hand in body-relative space, but it also modifies the perception of other body parts. In conclusion, we propose that the brain continuously strives to maintain a consistent internal body image and that this image can be influenced by the available sensory information sources, which are mediated and mapped onto each other by means of a postural, kinematic body model. PMID:24671172

Butz, Martin V; Kutter, Esther F; Lorenz, Corinna

2014-01-01

359

X-31 high angle of attack control system performance  

NASA Technical Reports Server (NTRS)

The design goals for the X-31 flight control system were: (1) level 1 handling qualities during post-stall maneuvering (30 to 70 degrees angle-of-attack); (2) thrust vectoring to enhance performance across the flight envelope; and (3) adequate pitch-down authority at high angle-of-attack. Additional performance goals are discussed. A description of the flight control system is presented, highlighting flight control system features in the pitch and roll axes and X-31 thrust vectoring characteristics. The high angle-of-attack envelope clearance approach will be described, including a brief explanation of analysis techniques and tools. Also, problems encountered during envelope expansion will be discussed. This presentation emphasizes control system solutions to problems encountered in envelope expansion. An essentially 'care free' envelope was cleared for the close-in-combat demonstrator phase. High angle-of-attack flying qualities maneuvers are currently being flown and evaluated. These results are compared with pilot opinions expressed during the close-in-combat program and with results obtained from the F-18 HARV for identical maneuvers. The status and preliminary results of these tests are discussed.

Huber, Peter; Seamount, Patricia

1994-01-01

360

View angle dependence of cloud optical thicknesses retrieved by MODIS  

NASA Technical Reports Server (NTRS)

This study examines whether cloud inhomogeneity influences the view angle dependence of MODIS cloud optical thickness (tau) retrieval results. The degree of cloud inhomogeneity is characterized through the local gradient in 11 microns brightness temperature. The analysis of liquid phase clouds in a one year long global dataset of Collection 4 MODIS data reveals that while optical thickness retrievals give remarkably consistent results for all view directions if clouds are homogeneous, they give much higher tau-values for oblique views than for overhead views if clouds are inhomogeneous and the sun is fairly oblique. For solar zenith angles larger than 55deg, the mean optical thickness retrieved for the most inhomogeneous third of cloudy pixels is more than 30% higher for oblique views than for overhead views. After considering a variety of possible scenarios, the paper concludes that the most likely reason for the increase lies in three-dimensional radiative interactions that are not considered in current, one-dimensional retrieval algorithms. Namely, the radiative effect of cloud sides viewed at oblique angles seems to contribute most to the enhanced tau-values. The results presented here will help understand cloud retrieval uncertainties related to cloud inhomogeneity. They complement the uncertainty estimates that will start accompanying MODIS cloud products in Collection 5 and may eventually help correct for the observed view angle dependent biases.

Marshak, Alexander; Varnai, Tamas

2005-01-01

361

Updated Results of Magnetic Resonance Imaging Guided Partial Prostate Brachytherapy for Favorable Risk Prostate Cancer: Implications for Focal Therapy  

PubMed Central

Purpose We report updated results of magnetic resonance imaging guided partial prostate brachytherapy and propose a definition of biochemical failure following focal therapy. Materials and Methods From 1997 to 2007, 318 men with cT1c, prostate specific antigen less than 15 ng/ml, Gleason 3 + 4 or less prostate cancer received magnetic resonance imaging guided brachytherapy in which only the peripheral zone was targeted. To exclude benign prostate specific antigen increases due to prostatic hyperplasia, we investigated the usefulness of defining prostate specific antigen failure as nadir +2 with prostate specific antigen velocity greater than 0.75 ng/ml per year. Cox regression was used to determine the factors associated with prostate specific antigen failure. Results Median followup was 5.1 years (maximum 12.1). While 36 patients met the nadir +2 criteria, 16 of 17 biopsy proven local recurrences were among the 26 men who also had a prostate specific antigen velocity greater than 0.75 ng/ml per year (16 of 26 vs 1 of 10, p = 0.008). Using the nadir +2 definition, prostate specific antigen failure-free survival for low risk cases at 5 and 8 years was 95.1% (91.0–97.3) and 80.4% (70.7–87.1), respectively. This rate improved to 95.6% (91.6–97.7) and 90.0% (82.6–94.3) using nadir +2 with prostate specific antigen velocity greater than 0.75 ng/ml per year. For intermediate risk cases survival was 73.0% (55.0–84.8) at 5 years and 66.4% (44.8–81.1) at 8 years (the same values as using nadir +2 with prostate specific antigen velocity greater than 0.75 ng/ml per year). Conclusions Requiring a prostate specific antigen velocity greater than 0.75 ng/ml per year in addition to nadir +2 appears to better predict clinical failure after therapies that target less than the whole gland. Further followup will determine whether magnetic resonance imaging guided brachytherapy targeting the peripheral zone produces comparable cancer control to whole gland treatment in men with low risk disease. However, at this time it does not appear adequate for men with even favorable intermediate risk disease.

Nguyen, Paul L.; Chen, Ming-Hui; Zhang, Yuanye; Tempany, Clare M.; Cormack, Robert A.; Beard, Clair J.; Hurwitz, Mark D.; Suh, W. Warren; D'Amico, Anthony V.

2013-01-01

362

Modal propagation angles in ducts with soft walls and their connection with suppressor performance  

NASA Technical Reports Server (NTRS)

The angles of propagation of the wave fronts associated with duct modes are derived for a cylindrical duct with soft walls (acoustic suppressors) and a uniform steady flow. The angle of propagation with respect to the radial coordinate (angle of incidence on the wall) is shown to be a better correlating parameter for the optimum wall impedance of spinning modes than the previously used mode cutoff ratio. Both the angle of incidence upon the duct wall and the propagation angle with respect to the duct axis are required to describe the attenuation of a propagating mode. Using the modal propagation angles, a geometric acoustics approach to suppressor acoustic performance was developed. Results from this approximate method were compared to exact modal propagation calculations to check the accuracy of the approximate method. The results are favorable except in the immediate vicinity of the modal optimum impedance where the approximate method yields about one-half of the exact maximum attenuation.

Rice, E. J.

1979-01-01

363

A Review of Mandibular Angle Fractures  

PubMed Central

After studying this article, the reader will be able to: (1) review the incidence and etiology of mandibular angle fractures; (2) gain an understanding of patient evaluation and general management principles; and (3) discuss indications and available techniques for management of mandibular angle fractures. Angle fractures represent the highest percentage of mandibular fractures. Two of the most common causes of mandibular angle fractures are motor vehicle accidents and assaults or altercations. With any patient who has sustained facial trauma, a thorough history and comprehensive physical examination centering on the head and neck region as well as proper radiological assessment are essential. These elements are fundamental in establishing a diagnosis and developing an appropriate treatment plan for any mandibular fracture.

Perez, Ramiro; Oeltjen, John C.; Thaller, Seth R.

2011-01-01

364

Hydrodynamic Model of Dynamic Contact Angle Hysteresis.  

National Technical Information Service (NTIS)

A qualitative hydrodynamic description of dynamic contact angle hysteresis is developed in terms of the interaction of capillary, viscous, and disjoining forces by considerating the slow motion of a fluid-fluid interface being driven through a capillary t...

R. J. Prutow S. Ostrach

1971-01-01

365

SOLARMAX/Electron Pitch Angle Anisotropy Distributions  

NASA Technical Reports Server (NTRS)

This final research report summarizes the scientific work performed by The Aerospace Corporation on SOLARMAX/Electron Pitch Angle Anisotropy Distributions. The period of performance was from June 1, 2000 to December 31, 2001.

McKenzie, David L.; Anderson, Phillip C.

2002-01-01

366

Laser Trabeculoplasty for Open-Angle Glaucoma.  

National Technical Information Service (NTIS)

In the hands of ophthalmologists experienced in this technology, argon laser trabeculoplasty is an appropriate treatment for open-angle glaucoma which remains uncontrolled despite maximal tolerated medical treatment. In view of its relatively low level of...

E. Feigenbaum

1984-01-01

367

Small Angle Silicon Detector System of CDF.  

National Technical Information Service (NTIS)

The physics goals that can be pursued using silicon detectors at very small angles inside the Tevatron beam pipe are discussed. These goals span a wide field, covering measurements of luminosity, elastic scattering, diffraction dissociation, determination...

S. Bertolucci M. Cordelli M. Curatolo B. Dulach B. Esposito

1985-01-01

368

Effect of Collision Angle on Mach Reflection,  

National Technical Information Service (NTIS)

Following the successful application of the HULL code to the modelling of shock waves colliding with a smooth planar surface, as described in a previous report, the influence of collision angle on reflection type was investigated. The numerical investigat...

J. A. Waschl

1987-01-01

369

Management algorithms for primary angle closure disease.  

PubMed

In contrast to primary open angle glaucoma, preventive interventions in primary angle closure disease (PACD) can sometimes be definitive. Data from randomized, controlled trials - and where this is not available - principles grounded in known biology, biological plausibility, logic, preferred practice and personal experience have been synthesized to develop explicit clinical algorithms for management of the spectrum of PACD. The mainstay of first-line intervention is usually a laser iridotomy: a commonly necessary but sometimes insufficient manoeuvre in PACD. The crucial stepwise considerations after iridotomy are: whether the angle is open or closed; whether the IOP can be medically controlled; the extent of PAS, and the presence of visually significant cataract. Indication for subsequent interventions--which may include iridoplasty, cataract surgery, trabeculectomy or phacotrabeulectomy--are herein based on an arbitrary threshold (180 degrees) for angle opening and extent of PAS following initial treatment. PMID:23009061

Thomas, Ravi; Walland, Mark J

2013-04-01

370

Radiative transfer in shrub savanna sites in Niger: Preliminary results from HAPEX-Sahel. Part 3: Optical dynamics and vegetation index sensitivity to biomass and plant cover  

NASA Technical Reports Server (NTRS)

A shrub savannah landscape in Niger was optically characterized utilizing blue, green, red and near-infrared wavelengths. Selected vegetation indices were evaluated for their performance and sensitivity to describe the complex Sahelian soil/vegetation canopies. Bidirectional reflectance factors (BRF) of plants and soils were measured at several view angles, and used as input to various vegetation indices. Both soil and vegetation targets had strong anisotropic reflectance properties, rendering all vegetation index (6) responses to be a direct function of sun and view geometry. Soil background influences were shown to alter the response of most vegetation indices. N-space greenness had the smallest dynamic range in VI response, but the n-space brightness index provided additional useful information. The global environmental monitoring index (GEMI) showed a large 6 dynamic range for bare soils, which was undesirable for a vegetation index. The view angle response of the normalized difference vegetation index (NDVI), atmosphere resistant vegetation index (ARVI) and soil atmosphere resistant vegetation index (SARVI) were asymmetric about nadir for multiple view angles, and were, except for the SARVI, altered seriously by soil moisture and/or soil brightness effects. The soil adjusted vegetation index (SAVI) was least affected by surface soil moisture and was symmetric about nadir for grass vegetation covers. Overall the SAVI, SARVI and the n-space vegetation index performed best under all adverse conditions and were recommended to monitor vegetation growth in the sparsely vegetated Sahelian zone.

vanLeeuwen, W. J. D.; Huete, A. R.; Duncan, J.; Franklin, J.

1994-01-01

371

A Unified Low-Elevation-Angle Scintillation Model  

NASA Astrophysics Data System (ADS)

Enabling communications at very low elevation angles can lengthen the duration of a tracking pass between a satellite and a ground station, which in turn can increase the amount of data return and possibly reduce the number of required supporting ground station tracking passes. Link performance, especially at very low angles and high frequencies, depends heavily on terrain, atmosphere, and weather conditions. Among the different contributions to attenuation, scintillation fading plays a very significant role and can impair the performance of the link. It is therefore necessary to accurately model the overall impact to the link due to scintillation fading. The current International Telecommunication Union ITU-R P.618-10 Recommendation describes three scintillation loss models as a function of elevation angle and percentage of time for which the loss exceeds a certain threshold. Implementation of the recommendation resulted in the uncovering of several issues. Particularly, it was identified that (i) iterative solutions to an implicit nonlinear exponential model, in some cases, are not guaranteed to exist, (ii) there is a discontinuity in fading values between models at the cross-over elevation angle, (iii) at certain low elevation angles scintillation from the shallow fade model generates unrealistically small losses, and (iv) for elevation angles lying between 4 and 5 deg, there are two applicable scintillation models that yield conflicting values. In this article, we develop a new approach to unify the different fading models within the current ITU recommendation and fully remove the discrepancies. We further validated our models with ITU-adopted scintillation data measured at Goonhilly, Great Britain, and data from several recent NASA Space Shuttle launches. This improved model was provisionally approved at the ITU International Meeting in Italy, November 2010, and is being evaluated by the ITU members for adoption into the next-version ITU Recommendation.

Lee, C. H.; Cheung, K.-M.; Ho, C.

2011-05-01

372

Solar Cell Angle of Incidence Corrections  

NASA Technical Reports Server (NTRS)

The Mars Pathfinder mission has three different solar arrays each of which sees changes in incidence angle during normal operation. When solar array angle of incidence effects was researched little published data was found. The small amount of-published data created a need to obtain and evaluate such data. The donation of the needed data, which was taken in the fall of 1994, was a major factor in the preparation of this paper.

Burger, Dale R.; Mueller, Robert L.

1995-01-01

373

Eliminating Deadbands In Resistive Angle Sensors  

NASA Technical Reports Server (NTRS)

Proposed shaft-angle-measuring circuit provides continuous indication of angle of rotation from 0 degree to 360 degrees. Sensing elements are two continuous-rotation potentiometers, and associated circuitry eliminates deadband that occurs when wiper contact of potentiometer crosses end contacts near 0 degree position of circular resistive element. Used in valve-position indicator or similar device in which long operating life and high angular precision not required.

Salomon, Phil M.; Allen, Russell O.; Marchetto, Carl A.

1992-01-01

374

Simple Map in Action-Angle Coordinates  

Microsoft Academic Search

The simple map is the simplest map that has the topology of a divertor tokamak. The simple map has three canonical representations: (i) the natural coordinates - toroidal magnetic flux and poloidal angle (psi,theta), (ii) the physical coordinates - the physical variables (R,Z) or (X,Y), and (iii) the action-angle coordinates - (J,theta) or magnetic coordinates (psi, theta). All three are

Olivia Kerwin; Alkesh Punjabi; Halima Ali

2008-01-01

375

Cut angles for quartz crystal resonators  

Microsoft Academic Search

The present invention concerns itself with crystallographically doubly rotated quartz orientations vibrating in the transverse c-mode with turnover temperatures which are considerably less sensitive to angular misorientation than the comparable well known AT- or BT-cuts. These crystals are arbitrarily designated as AK-cut crystals and are defined by phi-angle variations between 30 deg.-60 deg, and theta-angle variations between 12 deg.-32 deg.

A. Kahan

1985-01-01

376

Neutron spin echo scattering angle measurement (SESAME)  

SciTech Connect

We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-{mu}m-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutron reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for.

Pynn, R.; Fitzsimmons, M.R.; Fritzsche, H.; Gierlings, M.; Major, J.; Jason, A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); National Research Council, Canada, SIMS, Chalk River Laboratories, Chalk River, Ontario K0J 1P0 (Canada); Hahn-Meitner-Institut, Glienicker Str. 100, D-14109, Berlin (Germany); Max-Planck-Institut fuer Metallforschung, Heisenbergstr 3, D-70569, Stuttgart (Germany); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2005-05-15

377

An experimental study of the angle and temperature dependences of the spontaneous Brillouin shift in ethanol  

NASA Astrophysics Data System (ADS)

Brillouin light spectra of ethanol in a temperature range from 10 to 45°C were experimentally investigated by a scanning Fabry Perot interferometer. The measurement of spectra were performed at a detection angle of 90°, which is indicated by decreased elastically scattered light. The effect of detection angle in the range 70 to 110° was also observed. A strong dependence of the Brillouin shift on temperature and detection angle was found. The results are summarized in graphical form.

Kilicaslan, I.; Esen, C.

2005-08-01

378

Three-dimensional target motion analysis using angle and frequency measurements  

Microsoft Academic Search

It is well known that passive target tracking by a single observer, commonly referred to as target motion analysis (TMA), can be done using angle and\\/or frequency measurements. Depending on the measurement set, different passive tracking procedures result: angle-only tracking (AOT), frequency-only tracking (FOT), and angle\\/frequency tracking (AFT). Whereas the two-dimensional passive tracking problem has been solved for a multitude

K. Becker

2005-01-01

379

Evaluation of the Dunlap/Rippstein method for determination of femoral neck angles.  

PubMed

The accuracy of the Dunlap method, as modified by Rippstein, for measuring the femoral neck angles was evaluated using adult bodies. The results were correlated to measurements on the dissected femurs. The Dunlap/Rippstein method correlated well with the determinations made in the specimens. The accuracy of the method was within +/- 7 degrees for the anteversion angle and within -5 to +9 degrees for the head-neck-shaft angle. PMID:3993421

Reikerås, O; Høiseth, A; Reigstad, A

1985-01-01

380

Parameter dependence of conic angle of nanofibres during electrospinning  

NASA Astrophysics Data System (ADS)

This paper reports the dependence of conic angle of nanofibres on the processing and material parameters during electrospinning. Solutions of polyacrylonitrile (PAN) in dimethylformamide (DMF) with varied PAN concentrations were studied as the model systems, and they were electrospun into nanofibres at different high direct current (dc) voltages, flow rates and needle diameters. The dynamic and transient shear viscosities of the PAN/DMF solutions were characterized by a parallel-plate rheometer at varied shear rates. Rheological measurements showed that the PAN/DMF solutions behaved as Newtonian fluids at relatively low to medium shear rates, while the solutions with high PAN concentrations of 18 and 20 wt% exhibited a significant shear-thinning behaviour at high shear rates, especially in the case of transient shear mode. Experimental results indicated that at the electrostatic field of ~80 kV m-1 and needle inner diameter of 0.48 mm (22 gauge), the conic angle of the nanofibre envelope decreased from ~160° to ~75° with an increase in PAN concentration from 12 to 20 wt%; at the PAN concentration of 16 wt%, the conic angle increased nonlinearly from ~40° to ~160° with an increase in electric field from 50 to 140 kV m-1. In addition, experimental results showed that the needle inner diameter also noticeably influenced the conic angle. This study provided the experimental evidence useful for understanding the scaling properties of electrohydrodynamic jet motion for controllable electrospinning and process modelling.

Zhou, Zhengping; Wu, Xiang-Fa; Gao, Xueqin; Jiang, Long; Zhao, Yong; Fong, Hao

2011-11-01

381

Visual angle model for car-following theory  

NASA Astrophysics Data System (ADS)

The vast majority of car-following models are lack of the consideration of human drivers’ characteristics. Based on the fact that each driver of a following vehicle perceives closing-in or shying-away a leading vehicle in front of him/her, primarily due to changes in the apparent size of the leading vehicle, we improved the full velocity difference (FVD) model and presented a visual angle car-following model. This model is in view of the stimulus-response framework and uses the visual angle and the change rate of the visual angle as stimulus. Results from linear analysis showed that the neutral stability line is asymmetry and the width of the leading vehicle has a great impact on the stability of traffic flow. Numerical simulations obtained the same results as theoretical analysis clearly such as density wave, shrinking hysteresis, asymmetry and wide scattering. Thus, the introducing of the visual angle can explain some complex nature of traffic flow and contribute to the design of more realistic car-following models.

Jin, Sheng; Wang, Dian-Hai; Huang, Zhi-Yi; Tao, Peng-Fei

2011-06-01

382

Boundary Layer Leading Edge Receptivity to Sound at Incidence Angles.  

NASA Astrophysics Data System (ADS)

The leading edge receptivity to acoustic waves of two-dimensional parabolic bodies was investigated using a spatial solution of the Navier-Stokes equations in vorticity/stream function form in parabolic coordinates. The free-stream is composed of a uniform flow with a superposed periodic velocity fluctuation of small amplitude. The method follows that of Haddad & Corke(J. Fluid Mech.), 368, 1998 in which the solution for the basic flow and linearized perturbation flow are solved separately. We primarily investigated the effect of frequency and angle of incidence (-180^circ <= ? <= 180^circ) of the acoustic waves on the leading edge receptivity. The results at ?=0^circ were found to be in quantitative agreement with those of Haddad & Corke, and substantiated the Strouhal number scaling based on the nose radius. The results with sound waves at angles of incidence agreed qualitatively with the analysis of Hammerton & Kerschen (1992). These included a maximum receptivity at ?=90^circ, and an asymmetric variation in the receptivity with sound incidence angle, with minima at angles which were slightly less than ?=0^circ and 180^circ.

Erturk, E.; Corke, T. C.

1999-11-01

383

Secondary Trigeminal Neuralgia in Cerebellopontine Angle Tumors  

PubMed Central

The analysis of the treatment results in patients with cerebellopontine angle (CPA) tumors, manifested as trigeminal neuralgia (TN). During the 10-year period from 1998 to 2008, 14 patients with verified CPA tumors that had the typical manifestations of TN were operated on at our hospital (5.8% from all patients with TN who underwent surgery). In nine cases the epidermoid was identified; three patients had meningioma, one patient had acoustic neurinoma, and one patient had lipoma. The follow-up of all patients lasted at least 12 months. The intraoperative assessment identified the three variants of relationship between the tumors and neurovascular structures: (1) tumor grows around the trigeminal nerve; (2) the tumor causes compression and displacement of the trigeminal nerve; and (3) tumor presses the arterial vessel to the trigeminal nerve by moving the vessel or nerve. For six patients, with removal of tumor a microvascular decompression of the trigeminal nerve was performed. Complete pain relief was achieved in 12 patients (86%). TN is an expectative symptom of CPA tumors. The most frequent cause of secondary TN of CPA tumors is epidermoid. All patients with manifestations of TN should undergo the magnetic resonance imaging for early diagnosis of CPA tumor.

Shulev, Yury; Trashin, Alexander; Gordienko, Konstantin

2011-01-01

384

LDEF yaw and pitch angle estimates  

NASA Technical Reports Server (NTRS)

Quantification of the LDEF yaw and pitch misorientations is crucial to the knowledge of atomic oxygen exposure of samples placed on LDEF. Video camera documentation of the LDEF spacecraft prior to grapple attachment, atomic oxygen shadows on experiment trays and longerons, and a pinhole atomic oxygen camera placed on LDEF provided sources of documentation of the yaw and pitch misorientation. Based on uncertainty-weighted averaging of data, the LDEF yaw offset was found to be 8.1 plus or minus 0.6 degrees, allowing higher atomic oxygen exposure of row 12 than initially anticipated. The LDEF pitch angle offset was found to be 0.8 plus or minus 0.4 degrees, such that the space end was tipped forward toward the direction of travel. The resulting consequences of the yaw and pitch misorientation of LDEF on the atomic oxygen fluence is a factor of 2.16 increase for samples located on row 12, and a factor of 1.18 increase for samples located on the space end compared to that which would be expected for perfect orientation.

Banks, Bruce A.; Gebauer, Linda

1992-01-01

385

Wide-angle energy-momentum spectroscopy.  

PubMed

Light emission is defined by its distribution in energy, momentum, and polarization. Here, we demonstrate a method that resolves these distributions by means of wide-angle energy-momentum spectroscopy. Specifically, we image the back focal plane of a microscope objective through a Wollaston prism to obtain polarized Fourier-space momentum distributions, and disperse these two-dimensional radiation patterns through an imaging spectrograph without an entrance slit. The resulting measurements represent a convolution of individual radiation patterns at adjacent wavelengths, which can be readily deconvolved using any well-defined basis for light emission. As an illustrative example, we use this technique with the multipole basis to quantify the intrinsic emission rates for electric and magnetic dipole transitions in europium-doped yttrium oxide (Eu3+:Y2O3) and chromium-doped magnesium oxide (Cr3+:MgO). Once extracted, these rates allow us to reconstruct the full, polarized, two-dimensional radiation patterns at each wavelength. PMID:24978773

Dodson, Christopher M; Kurvits, Jonathan A; Li, Dongfang; Zia, Rashid

2014-07-01

386

Angle-independent structural colors of silicon  

NASA Astrophysics Data System (ADS)

Structural colors are optical phenomena of physical origin, where microscale and nanoscale structures determine the reflected spectrum of light. Artificial structural colors have been realized within recent years. However, multilayer structures require substantial fabrication. Instead we considered one-layer surface textures of silicon. We explored four patterns of square structures in a square lattice with periods of 500, 400, 300, and 200 nm. The reflectivity and daylight-colors were measured and compared with simulations based on rigorously coupled-wave analysis with excellent agreement. Based on the 200-nm periodic pattern, it was found that angle-independent specular colors up to 60 deg of incidence may be provided. The underlying mechanisms include (1) the suppression of diffraction and (2) a strong coupling of light to localized surface states. The strong coupling yields absorption anomalies in the visual spectrum, causing robust colors to be defined for a large angular interval. The result is a manifestation of a uniformly defined color, similar to pigment-based colors. These mechanisms hold potential for color engineering and can be used to explain and predict the structural-color appearance of silicon-based textures for a wide range of structural parameters.

Højlund-Nielsen, Emil; Weirich, Johannes; Nørregaard, Jesper; Garnaes, Joergen; Asger Mortensen, N.; Kristensen, Anders

2014-01-01

387

Asymmetric dihedral angle offsets for large-size lunar laser ranging retroreflectors  

NASA Astrophysics Data System (ADS)

The distribution of two-dimensional velocity aberration is off-centered by 5 to 6 microradians in lunar laser ranging, due to the stable measurement geometry in the motion of the Earth and the Moon. The optical responses of hollow-type retroreflectors are investigated through numerical simulations, especially focusing on large-size, single-reflector targets that can ultimately minimize the systematic error in future lunar laser ranging. An asymmetric dihedral angle offset, i.e. setting unequal angles between the three back faces, is found to be effective for retroreflectors that are larger than 100 mm in diameter. Our numerical simulation results reveal that the optimized return energy increases approximately 3.5 times more than symmetric dihedral angle cases, and the optimized dihedral angle offsets are 0.65-0.8 arcseconds for one angle, and zeroes for the other two angles.

Otsubo, T.; Kunimori, H.; Noda, H.; Hanada, H.; Araki, H.; Katayama, M.

2011-08-01

388

Diminution of Contact Angle Hysteresis under the Influence of an Oscillating Force.  

PubMed

We suggest a simple quantitative model for the diminution of contact angle hysteresis under the influence of an oscillatory force invoked by thermal fluctuations, substrate vibrations, acoustic waves, or oscillating electric fields. Employing force balance rather than the usual description of contact angle hysteresis in terms of Gibbs energy, we highlight that a wetting system, such as a sessile drop or a bubble adhered to a solid substrate, appears at long times to be partially or fully independent of contact angle hysteresis and thus independent of static friction forces, as a result of contact line pinning. We verify this theory by studying several well-known experimental observations such as the approach of an arbitrary contact angle toward the Young contact angle and the apparent decrease (or increase) in an advancing (or a receding) contact angle under the influence of an external oscillating force. PMID:24856418

Manor, Ofer

2014-06-17

389

Passive yaw damping of a teetered rotor versus delta-3 angle values  

NASA Astrophysics Data System (ADS)

A series of preliminary experiments are used to delineate the combinations of passive cyclic pitching conditions which are favorable. The conditions surveyed include: (1) upwind and downwind modes of operation; (2) a wide range of delta3 angle settings, from +70 degrees to -70 degrees; (3) rotor angular speeds from 300 to 750 rpm; and (4) the resulting ranges of teeter angles and yaw rates. Negative settings of the delta3 angle and large positive delta3 values cause pronounced instabilities for both upward and downwind modes. With delta3 angle settings from 0 degrees to 45 degrees the teetered rotor in the downwind mode ran at a continuous yaw angle to the free stream wind. Midrange delta3 angle values for an upwind, tailvane stabilized, rotor are favorable.

Bryant, P. J.

390

Factors influencing the effective spray cone angle of pressure-swirl atomizers  

NASA Technical Reports Server (NTRS)

The spray cone angles produced by several simplex pressure-swirl nozzles are examined using three liquids whose viscosities range from 0.001 to 0.012 kg/ms (1 to 12 cp). Measurements of both the visible spray cone angle and the effective spray cone angle are carried out over wide ranges of injection pressure and for five different values of the discharge orifice length/diameter ratio. The influence of the number of swirl chamber feed slots on spray cone angle is also examined. The results show that the spray cone angle widens with increase in injection pressure but is reduced by increases in liquid viscosity and/or discharge orifice length/diameter ratio. Variation in the number of swirl chamber feed slots between one and three has little effect on the effective spray cone angle.

Chen, S. K.; Lefebvre, A. H.; Rollbuhler, J.

1992-01-01

391

Fractal Approach in Petrology: Combining Ultra-Small Angle (USANA) and Small Angle Neutron Scattering (SANS)  

SciTech Connect

Ultra small angle neutron scattering instruments have recently covered the gap between the size resolution available with conventional intermediate angle neutron scattering and small angle neutron scattering instruments on one side and optical microscopy on the other side. Rocks showing fractal behavior in over two decades of momentum transfer and seven orders of magnitude of intensity are examined and fractal parameters are extracted from the combined USANS and SANS curves.

LoCelso, F.; Triolo, F.; Triolo, A.; Lin, J.S.; Lucido, G.; Triolo, R.

1999-10-14

392

Acquisition and analysis of angle-beam wavefield data  

NASA Astrophysics Data System (ADS)

Angle-beam ultrasonic testing is a common practical technique used for nondestructive evaluation to detect, locate, and characterize a variety of material defects and damage. Greater understanding of the both the incident wavefield produced by an angle-beam transducer and the subsequent scattering from a variety of defects and geometrical features is anticipated to increase the reliability of data interpretation. The focus of this paper is on acquiring and analyzing propagating waves from angle-beam transducers in simple, defect-free plates as a first step in the development of methods for flaw characterization. Unlike guided waves, which excite the plate throughout its thickness, angle-beam bulk waves bounce back and forth between the plate surfaces, resulting in the well-known multiple "skips" or "V-paths." The experimental setup consists of a laser vibrometer mounted on an XYZ scanning stage, which is programmed to move point-to-point on a rectilinear grid to acquire waveform data. Although laser vibrometry is now routinely used to record guided waves for which the frequency content is below 1 MHz, it is more challenging to acquire higher frequency bulk waves in the 1-10 MHz range. Signals are recorded on the surface of an aluminum plate that were generated from a 5 MHz, 65° refracted angle, shear wave transducer-wedge combination. Data are analyzed directly in the x-t domain, via a slant stack Radon transform in the ?-p (offset time-slowness) domain, and via a 2-D Fourier transform in the ?-k domain, thereby enabling identification of specific arrivals and modes. Results compare well to those expected from a simple ray tracing analysis except for the unexpected presence of a strong Rayleigh wave.

Dawson, Alexander J.; Michaels, Jennifer E.; Levine, Ross M.; Chen, Xin; Michaels, Thomas E.

2014-02-01

393

In situ estimation of sediment sound speed and critical angle  

PubMed

Understanding the basic physics of sound penetration into ocean sediments is essential for the design of sonar systems that can detect, localize, classify, and identify buried objects. In this regard the sound speed of the sediment is a crucial parameter as the ratio of sound speed at the water-sediment interface determines the critical angle. Sediment sound speed is typically measured from core samples using high frequency (100's of kHz) pulsed travel time measurements. Earlier experimental work on subcritical penetration into sandy sediments has suggested that the effective sound speed in the 2-20 kHz range is significantly lower than the core measurement results. Simulations using Biot theory for propagation in porous media confirmed that sandy sediments may be highly dispersive in the range 1-100 kHz for the type of sand in which the experiments were performed. Here it is shown that a direct and robust estimate of the critical angle, and therefore the sediment sound speed, at the lower frequencies can be achieved by analyzing the grazing angle dependence of the phase delays observed on a buried array. A parametric source with secondary frequencies in the 2-16 kHz range was directed toward a sandy bottom similar to the one investigated in the earlier study. An array of 14 hydrophones was used to measure penetrated field. The critical angle was estimated by analyzing the variations of signal arrival times versus frequency, burial depth, and grazing angle. Matching the results with classical transmission theory yielded a sound speed estimate in the sand of 1626 m/s in the frequency range 2-5 kHz, again significantly lower the 1720 m/s estimated from the cores at 200 kHz. However, as described here, this dispersion is consistent with the predictions of the Biot theory for this type of sand. PMID:11008802

Maguer; Bovio; Fox; Schmidt

2000-09-01

394

IMU-based joint angle measurement for gait analysis.  

PubMed

This contribution is concerned with joint angle calculation based on inertial measurement data in the context of human motion analysis. Unlike most robotic devices, the human body lacks even surfaces and right angles. Therefore, we focus on methods that avoid assuming certain orientations in which the sensors are mounted with respect to the body segments. After a review of available methods that may cope with this challenge, we present a set of new methods for: (1) joint axis and position identification; and (2) flexion/extension joint angle measurement. In particular, we propose methods that use only gyroscopes and accelerometers and, therefore, do not rely on a homogeneous magnetic field. We provide results from gait trials of a transfemoral amputee in which we compare the inertial measurement unit (IMU)-based methods to an optical 3D motion capture system. Unlike most authors, we place the optical markers on anatomical landmarks instead of attaching them to the IMUs. Root mean square errors of the knee flexion/extension angles are found to be less than 1° on the prosthesis and about 3° on the human leg. For the plantar/dorsiflexion of the ankle, both deviations are about 1°. PMID:24743160

Seel, Thomas; Raisch, Jörg; Schauer, Thomas

2014-01-01

395

Effects of temperature and conditioning on contact lens wetting angles.  

PubMed

Because wettability is not always examined under standard conditions, we investigated the temperature dependence of saline wettability on unconditioned and conditioned polymethylmethacrylate (PMMA), cellulose acetate butyrate (CAB), and three silicone acrylate lens materials. Sessile drop contact angles were measured in a humidity chamber at 23 degrees C and 34 degrees C using laser-assisted contact angle goniometry. In separate experiments, saline-stored and preconditioned lenses were examined either with or without rinsing. Sessile drop contact angles at 34 degrees C were within 2 degrees to 5 degrees of the room temperature values for both conditioned and unconditioned lenses, demonstrating a negligible temperature dependence. At both temperatures, the conditioned PMMA, CAB, silafocon A, and pasifocon C lenses wet slightly better, by 1 degree to 12 degrees, than unconditioned lenses. However, this increase was only significant with PMMA and silafocon A (P less than 0.05) and reversed when the preconditioned lenses were rinsed repeatedly in saline and reexamined. The results suggest that for these materials: 1) in vitro saline contact angles do not approach those seen on the eye, and this discrepancy can not be explained by temperature or conditioning; and 2) conditioning does not increase material wettability but merely forms a temporary hydrophilic interface that is more wettable than the lens material. PMID:1654228

Knick, P D; Huff, J W

1991-07-01

396

Improving gated cardiac scanning using limited-angle reconstruction technique  

SciTech Connect

Selected phases of the cardiac cycle can be imaged by the method of gated cardiac scanning using whole body scanners. However, since there is no synchronization between the random heart beats and the CT machine, the output will have gaps in the angular coverage of each scan. The missing projections in these gaps result in artifacts in the reconstructed images. In this paper, the technique of limited-angle reconstruction is employed to fill in the missing projections to remove the artifacts. The object is transformed back and forth between the object space and the projection space, being corrected in each step by the constraints of the finite spatial extent and of the upper and lower bounds of the object in the object space, and the known projections in the projection space. It is found that by using the proposed algorithm the rms errors of the limited-angle images are reduced to a level comparable to those of the complete-angle images. The same iteration algorithm can also be used to reduce the fan beam scanning angle from 360 degree to 180 degree without sacrificing much image quality.

Tam, K.C.; Perez-Mendez, V.

1983-02-01

397

Mathematical analysis of furcation angle in extracted mandibular molars  

PubMed Central

Background: Multi-rooted teeth with furcation involvement exhibit a poorer prognosis when compared to single rooted teeth. The furcation angle (formed by the divergent roots and the roof) may exert a considerable influence on the accessibility for both home care maintenance and instrumentation during periodontal therapy. As there are few anatomy based reports, the furcation angle has not yet been delineated. Materials and Methods: Furcation angle (FA) was mathematically evaluated in extracted mandibular first and second molar teeth, using the Computer-aided design - computer-aided manufacturing technology. Results: The furcations were divided into three groups (Group I: <30°, Group II: 30°-60°, Group III: >60°) based on the furcation angle and their prevalence. The first molar showed greater prevalence of group II FA, while second molar showed a greater prevalence of group III FA. Conclusion: Linear, two dimensional measurements may not accurately reflect the complexities of the furcation area which exhibits considerable intermolar and intramolar (buccal and lingual furcations of second molar) variation.

James, Johnson R.; Arun, K. V.; Talwar, Avaneendra; Kumar, T. S. S.

2013-01-01

398

IMU-Based Joint Angle Measurement for Gait Analysis  

PubMed Central

This contribution is concerned with joint angle calculation based on inertial measurement data in the context of human motion analysis. Unlike most robotic devices, the human body lacks even surfaces and right angles. Therefore, we focus on methods that avoid assuming certain orientations in which the sensors are mounted with respect to the body segments. After a review of available methods that may cope with this challenge, we present a set of new methods for: (1) joint axis and position identification; and (2) flexion/extension joint angle measurement. In particular, we propose methods that use only gyroscopes and accelerometers and, therefore, do not rely on a homogeneous magnetic field. We provide results from gait trials of a transfemoral amputee in which we compare the inertial measurement unit (IMU)-based methods to an optical 3D motion capture system. Unlike most authors, we place the optical markers on anatomical landmarks instead of attaching them to the IMUs. Root mean square errors of the knee flexion/extension angles are found to be less than 1° on the prosthesis and about 3° on the human leg. For the plantar/dorsiflexion of the ankle, both deviations are about 1°.

Seel, Thomas; Raisch, Jorg; Schauer, Thomas

2014-01-01

399

Relating dynamic contact angle to wetting front instability  

NASA Astrophysics Data System (ADS)

Dynamic contact angles have been implied as a mechanism for initiating the instability of wetting fronts and the formation of gravity fingers/columns in porous media. To study those dynamic contact angles when gravity effects are present, rectangular capillary tubes are used to facilitate the observation of the complete interface without geometric distortion. Results show that the dynamic contact angle minus the static contact angle has a unique relationship with the capillary number which is function of the velocity of the slug, and surface tension and viscosity of the fluid. Using this relationship and making the assumption that the fluid velocity through the pores is related but not equal to the finger velocity, earlier findings of DiCarlo on the capillary overshoot at the wetting front can be reproduced well. This study confirms that dynamic contact plays a critical role in the formation of unstable finger flow. It also points a way to calculate the capillary pressure at the wetting from as a function of the flux in the finger and the grain size diameter.

Baver, Christine; Parlange, J.-Yves; Stoof, Cathelijne; DiCarlo, David; Wallach, Rony; Steenhuis, Tammo

2013-04-01

400

On the dip angle of subducting plates  

NASA Technical Reports Server (NTRS)

A new approximate analytic model is developed for the thermal structure of a subducting plate with a finite length. This model provides the capability of easily examining the thermal and mechanical structure of a subducting plate with different lengths and at different angles. Also, the torque balance of a descending plate can be examined, and effects such as the leading edge effect, the adiabatic compression effect, and the phase change effect can be incorporated. A comparison with observed data indicates that short slabs are likely under torque equilibrium at present, while long slabs are probably dominated by their gravitational torques such that their dip angles are transient, moving toward a steeper dip angle similar to that of the Mariana slab.

Hsui, Albert T.; Tang, Xiao-Ming; Toksoz, M. Nafi

1990-01-01

401

Fluctuating flow angles and anisotropic flow measurements  

NASA Astrophysics Data System (ADS)

Event-by-event fluctuations in the initial density distributions of the fireballs created in relativistic heavy-ion collisions lead to event-by-event fluctuations of the final anisotropic flow angles, and density inhomogeneities in the initial state cause these flow angles to vary with the transverse momentum of the emitted particles. It is shown that these effects lead to characteristically different transverse momentum dependencies for anisotropic flow coefficients extracted from different experimental methods. These differences can be used to experimentally constrain flow angle fluctuations in the final state of heavy-ion collisions which, in turn, are sensitive to the initial-state density fluctuations and the shear viscosity of the expanding fireball medium.

Heinz, Ulrich; Qiu, Zhi; Shen, Chun

2013-03-01

402

Small Angle X-Ray Scattering Detector  

DOEpatents

A detector for time-resolved small-angle x-ray scattering includes a nearly constant diameter, evacuated linear tube having an end plate detector with a first fluorescent screen and concentric rings of first fiber optic bundles for low angle scattering detection and an annular detector having a second fluorescent screen and second fiber optic bundles concentrically disposed about the tube for higher angle scattering detection. With the scattering source, i.e., the specimen under investigation, located outside of the evacuated tube on the tube's longitudinal axis, scattered x-rays are detected by the fiber optic bundles, to each of which is coupled a respective photodetector, to provide a measurement resolution, i.e., dq/q, where q is the momentum transferred from an incident x-ray to an x-ray scattering specimen, of 2% over two (2) orders of magnitude in reciprocal space, i.e., qmax/qmin approx=lO0.

Hessler, Jan P.

2004-06-15

403

Star tracker axis-to-sunlit earth horizon angle constraint evaluations for rendezvous operations  

NASA Technical Reports Server (NTRS)

The results are presented of a study initiated to evaluate the star tracker axis-to-sunlit earth horizon angle constraint with respect to limitations imposed on the passive target rendezvous capability. The data presented include considerations for dispersions and sensor pointing capabilities and generalizations with respect to the uncertainties associated with the angle constraint available in practice.

Hutchison, W. L.

1975-01-01

404

Contact-Angle Hysteresis Caused by a Random Distribution of Weak Heterogeneities on a Solid Surface  

Microsoft Academic Search

A model according to which contact-angle hysteresis arises as the result of a random distribution of irregularities on the solid surface is investigated on the basis of probability theory. An estimate is obtained of the mathematical expectation of the number of stable equilibria when the effective angle between the liquid–gas surface and the solid surface with which the liquid is

U. Öpik

2000-01-01

405

Tire cornering properties at large camber angles: mechanism of the moment around the vertical axis  

Microsoft Academic Search

In this paper a one-dimensional discrete brush model is described. The new model contains a twisting concept along a trajectory of tread base and explains the mechanism of moment around the vertical axis at large camber angles. Calculations are focused on tires for motorcycles, since motorcycles often use tires under the condition of large camber angles. The calculated results are

Takehiko Fujioka; Kenjiro Goda

1995-01-01

406

Exact quantum cross sections for a three dimensional angle dependent model for three body reactions.  

NASA Technical Reports Server (NTRS)

Exact quantum mechanical reactive cross sections are reported for a three dimensional angle dependent model surface. The surface simulates an atom-heteronuclear diatom system A + BC leading to AB + C where atom B is much heavier than A or C. The molecules BC and AB are taken to be rotating vibrators which can dissociate. Results for two angle dependent potentials are given.

Baer, M.; Kouri, D. J.

1971-01-01

407

Development and evaluation of the interferometric monitor for greenhouse gases: a high-throughput fourier-transform infrared radiometer for nadir earth observation.  

PubMed

The interferometric monitor for greenhouse gases (IMG) was the precursor of the high-resolution Fourier-transform infrared radiometer (FTIR) onboard a satellite for observation of the Earth. The IMG endured the stress of a rocket launch, demonstrating that the high-resolution, high-throughput spectrometer is indeed feasible for use onboard a satellite. The IMG adopted a newly developed lubricant-free magnetic suspension mechanism and a dynamic alignment system for the moving mirror with a maximum traveling distance of 10 cm. We present the instrumentation of the IMG, characteristics of the movable mirror drive system, and the evaluation results of sensor specifications during space operation. PMID:18324219

Kobayashi, H; Shimota, A; Kondo, K; Okumura, E; Kameda, Y; Shimoda, H; Ogawa, T

1999-11-20

408

The hallux valgus angle of the margo medialis pedis as an alternative to the measurement of the metatarsophalangeal hallux valgus angle  

PubMed Central

Background Currently, the metatarsophalangeal angle (hallux valgus angle) is measured based on radiographic images. However, using X-ray examinations for epidemiological or screening purposes would be unethical, especially in children. For this reason it is discussed to measure the hallux valgus angle of the margo medialis pedis (medial border of the foot) documented on foot outline drawings or foot scans. As a first step on the way to prove the validity of those approaches this study assesses the hallux valgus angle measured on the margo medialis pedis based on the same x-ray pictures as the metatarsophalangeal hallux valgus. Methods Radiographic images of the foot were obtained from patients with symptomatic hallux valgus malformation. Twelve sets of contact copies of the 63 originals were made, and were marked and measured according to three different methods, each one performed by two observers and with two repeated measurements. Thus, data sets from 756 individual assessments were entered into the multifactorial statistical analysis. Comparisons were made between the angle of the margo medialis pedis and the metatarsophalangeal angle, which was determined by two different methods. To determine the inter- and intraobserver reliability of the different methods, each assessment was conducted by two independent experts and repeated after a period of several weeks. Results The correlations between the hallux valgus angles determined by the three different methods were all above r?=?0.89 (p?angle, however, were on average 4.8 degrees smaller than the metatarsophalangeal angles. No significant differences were found between the observers. No systematic deviations for any observer between repeated measurements were detected. Conclusions Measurements of the radiographic hallux angle of the margo medialis pedis are reliable and show high correlation with the metatarsophalangeal angle. Because the hallux valgus angles based on margo medialis pedis measurements were slightly but statistically significantly smaller, these measurements should be considered conservative estimates of the metatarsophalangeal angle. Significant differences between hallux valgus angles based on radiographic and non-radiographic material are unlikely. However this question has to be treated in a second stage in detail.

2014-01-01

409

Contact angle and stability of interfacial nanobubbles.  

PubMed

Small bubbles of gas are known to exist at the interface between hydrophobic solids and water. Two features of these bubbles are unexplained: the very low contact angle and the stability. A self-consistent explanation of both of these effects is that there is a film of contaminant at the air-water interface that decreases the surface tension and thus the contact angle, and also hinders diffusion of gases from the bubble, thereby increasing the lifetime. If, during the lifetime of the bubble, the surface tension increases faster than the area of the air-water decreases, the interfacial energy can lead to a stabilization of the bubbles. PMID:19624143

Ducker, William A

2009-08-18

410

Rapid emission angle selection for rotating-shield brachytherapy  

PubMed Central

Purpose: The authors present a rapid emission angle selection (REAS) method that enables the efficient selection of the azimuthal shield angle for rotating shield brachytherapy (RSBT). The REAS method produces a Pareto curve from which a potential RSBT user can select a treatment plan that balances the tradeoff between delivery time and tumor dose conformity. Methods: Two cervical cancer patients were considered as test cases for the REAS method. The RSBT source considered was a Xoft AxxentTM electronic brachytherapy source, partially shielded with 0.5 mm of tungsten, which traveled inside a tandem intrauterine applicator. Three anchor RSBT plans were generated for each case using dose-volume optimization, with azimuthal shield emission angles of 90°, 180°, and 270°. The REAS method converts the anchor plans to treatment plans for all possible emission angles by combining neighboring beamlets to form beamlets for larger emission angles. Treatment plans based on exhaustive dose-volume optimization (ERVO) and exhaustive surface optimization (ERSO) were also generated for both cases. Uniform dwell-time scaling was applied to all plans such that that high-risk clinical target volume D90 was maximized without violating the D2cc tolerances of the rectum, bladder, and sigmoid colon. Results: By choosing three azimuthal emission angles out of 32 potential angles, the REAS method performs about 10 times faster than the ERVO method. By setting D90 to 85–100 Gy10, the delivery times used by REAS generated plans are 21.0% and 19.5% less than exhaustive surface optimized plans used by the two clinical cases. By setting the delivery time budget to 5–25 and 10–30 min/fx, respectively, for two the cases, the D90 contributions for REAS are improved by 5.8% and 5.1% compared to the ERSO plans. The ranges used in this comparison were selected in order to keep both D90 and the delivery time within acceptable limits. Conclusions: The REAS method enables efficient RSBT treatment planning and delivery and provides treatment plans with comparable quality to those generated by exhaustive replanning with dose-volume optimization.

Liu, Yunlong; Flynn, Ryan T.; Yang, Wenjun; Kim, Yusung; Bhatia, Sudershan K.; Sun, Wenqing; Wu, Xiaodong

2013-01-01

411

Everything SAXS: small-angle scattering pattern collection and correction  

NASA Astrophysics Data System (ADS)

For obtaining reliable nanostructural details of large amounts of sample—and if it is applicable—small-angle scattering (SAS) is a prime technique to use. It promises to obtain bulk-scale, statistically sound information on the morphological details of the nanostructure, and has thus led to many a researcher investing their time in it over the last eight decades of development. Due to pressure from scientists requesting more details on increasingly complex nanostructures, as well as the ever improving instrumentation leaving less margin for ambiguity, small-angle scattering methodologies have been evolving at a high pace over the past few decades. As the quality of any results can only be as good as the data that go into these methodologies, the improvements in data collection and all imaginable data correction steps are reviewed here. This work is intended to provide a comprehensive overview of all data corrections, to aid the small-angle scatterer to decide which are relevant for their measurement and how these corrections are performed. Clear mathematical descriptions of the corrections are provided where feasible. Furthermore, as no quality data exist without a decent estimate of their precision, the error estimation and propagation through all these steps are provided alongside the corrections. With these data corrections, the collected small-angle scattering pattern can be made of the highest standard, allowing for authoritative nanostructural characterization through its analysis. A brief background of small-angle scattering, the instrumentation developments over the years, and pitfalls that may be encountered upon data interpretation are provided as well.

Pauw, Brian Richard

2013-09-01

412

The Effects of Approach Angle on Penalty Kicking Accuracy and Kick Kinematics with Recreational Soccer Players  

PubMed Central

Kicking accuracy is an important component of successful penalty kicks, which may be influenced by the approach angle. The purpose of this study was to examine the effects of approach angle on kicking accuracy and three-dimensional kinematics of penalty kicks. Seven male amateur recreational soccer players aged (mean ± s) 26 ± 3 years, body mass 74.0 ± 6.8 kg, stature 1.74 ± 0.06 m, who were right foot dominant, kicked penalties at a 0.6 x 0.6 m target in a full size goal from their self-selected approach angle, 30°, 45° and 60° (direction of the kick was 0°). Kicking accuracy and three-dimensional kinematics were recorded. Results revealed that there was no significant difference in kicking accuracy (p = 0.27) or ball velocity (p = 0.59) between the approach angles. Pelvic rotation was significantly greater under the 45° and the 60° approach angles than during the self-selected approach angle (p < 0.05). Thigh abduction of the kicking leg at impact using the 60° approach angle was significantly greater than during the self- selected approach (p = 0.01) and the 30° approach (p = 0.04). It was concluded that altering an individual’s self-selected approach angle at recreational level did not improve kicking accuracy or ball velocity, despite altering aspects of underlying technique. Key points Penalty kicking accuracy and ball velocity were not improved by altering recreational soccer players’ natural approach angle. However, widening the approach angle produced greater pelvic rotation and thigh abduction. Wider approach angles increased the range of motion of the pelvis, opening up the hips before ball contact, creating a greater arc of movement during the backswing and the follow-through. Wider approach angles also led to an increase in thigh abduction at impact, enabling the kicking foot to be placed further under the ball, which may improve ball contact.

Scurr, Joanna; Hall, Ben

2009-01-01

413

The relationship between bioelectrical impedance phase angle and subjective global assessment in advanced colorectal cancer  

PubMed Central

Background Bioelectrical Impedance (BIA) derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA) is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. Methods We evaluated a case series of 73 stages III and IV colorectal cancer patients. Patients were classified as either well-nourished or malnourished using the SGA. BIA was conducted on all patients and phase angle was calculated. The correlation between phase angle and SGA was studied using Spearman correlation coefficient. Receiver Operating Characteristic curves were estimated using the non-parametric method to determine the optimal cut-off levels of phase angle. Results Well-nourished patients had a statistically significantly higher (p = 0.005) median phase angle score (6.12) as compared to those who were malnourished (5.18). The Spearman rank correlation coefficient between phase angle and SGA was found to be 0.33 (p = 0.004), suggesting better nutritional status with higher phase angle scores. A phase angle cut-off of 5.2 was 51.7% sensitive and 79.5% specific whereas a cut-off of 6.0 was 82.8% sensitive and 54.5% specific in detecting malnutrition. Interestingly, a phase angle cut-off of 5.9 demonstrated high diagnostic accuracy in males who had failed primary treatment for advanced colorectal cancer. Conclusion Our study suggests that bioimpedance phase angle is a potential nutritional indicator in advanced colorectal cancer. Further research is needed to elucidate the optimal cut-off levels of phase angle that can be incorporated into the oncology clinic for better nutritional evaluation and management.

Gupta, Digant; Lis, Christopher G; Dahlk, Sadie L; King, Jessica; Vashi, Pankaj G; Grutsch, James F; Lammersfeld, Carolyn A

2008-01-01

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