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1

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

2

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

3

Reflectance anisotropy for nadir observations of coniferous forest canopies  

SciTech Connect

Nadir-viewed reflectances from forest canopies in four spectral bands, centered at 485 nm, 654 nm, 841 nm, and 1,676 nm were measured at different sun angles. Reflectances were measured made from a helicopter ca. 10 km NE of Stockholm, Sweden, over mature and young stands of Scotch pine (Pinus sylvestris) and Norway spruce (Picea abies). The results show a significant increase in nadir reflectance with decreasing solar zenith angle. On the average, reflectance factors increased by 1--2% for each degree of decreasing solar zenith angle. Band ratios showed that there is a disproportional reflectance response in several of the spectral bands at varying zenith angles, differently expressed according to stand type and age. Within the solar zenith angle interval 30--70[degree], canopy reflectance was expressed as linear functions for each spectral band. These functions were used to calculate factors for reflectance standardization. Nomograms, containing reflectance correction factors for mature spruce stands, are presented. These can be directly applied in time-series analysis of multitemporal spectral data.

Syren, P. (Stockholm Univ. (Sweden). Lab. of Remote Sensing)

1994-07-01

4

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

5

Monitoring the Terra and Aqua MODIS RSB calibration using scattered light from the Nadir-port  

NASA Astrophysics Data System (ADS)

MODIS is currently onboard NASA's EOS Terra and Aqua spacecraft launched on December 18, 1999 and May 4, 2002, respectively. MODIS reflective solar bands (RSB) are calibrated on-orbit using solar illumination reflected from its onboard solar diffuser (SD). The solar diffuser stability monitor (SDSM) is designed to track the on-orbit degradation of the SD via alternate observations of the Sun and SD. A wavelength-dependent degradation pattern is observed for both MODIS instruments with a faster degradation rate observed at shorter wavelengths. The UV exposure of the SD to sunlight and the scattered light (the sunlight reflected from top of the atmosphere) through the instrument nadir port contributes to its reflectance degradation. The scatter off the diffuser onto the scan mirror is in the forward direction, whereas the scatter off the diffuser onto the SDSM scan mirror is in the backward direction. Since the outgoing angles (viewed by MODIS detectors) are the same as the scheduled SD calibration, the gain derived from scattering light facilitates monitoring the dependence on SD degradation on incident angles. A methodology is formulated to track the MODIS SD degradation using scattered light through the nadir-port and comparing the result with the SD degradation as measured by the SDSM. In this study, multiple orbits from a given day of each month are processed to obtain a SD response to the nadir-port illumination. Results show that a reasonable agreement is observed between the SD degradation estimates derived from both view-angles.

Angal, Amit; Xiong, Xiaoxiong; Geng, Xu; Sun, Junqiang

2014-09-01

6

Recent Results on the CKM Angle Alpha  

SciTech Connect

The method to measure the CKM angle {alpha} and the modes sensitive to it are discussed. It is shown that the B {yields} {rho}{rho} decays provide the most stringent constraint on {alpha}, which is found to be {alpha} = 96{sup o} {+-} 10{sup o}(stat) {+-} 4{sup o}(syst){+-} 13{sup o}(penguin).

Mihalyi, A.; /Wisconsin U., Madison

2005-10-18

7

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. ...

Mr Clark

2012-10-31

8

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. PMID:24773608

2014-01-01

9

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.

Jo Edkins

2007-01-01

10

Angles  

NSDL National Science Digital Library

This interactive Flash applet enables students, using estimation and measurement skills, to investigate angles. Teachers can use this page for demonstrating how to read a protractor, and the protractor can be hidden to give students practice in estimating angle measures. The size of the angle can be controlled or chosen randomly.

Dan Bunker

2011-01-01

11

Angles  

NSDL National Science Digital Library

This Java applet enables students to investigate acute, obtuse, and right angles. The student decides to work with one or two transversals and a pair of parallel lines. Angle measure is given for one angle. The student answers a short series of questions about the size of other angles, identifying relationships such as vertical and adjacent angles and alternate interior and alternate exterior angles. In addition to automatically checking the student's answers, the applet can keep score of correct answers. From the activity page, What, How, and Why buttons open pages that explain the activity's purpose, function, and how the mathematics fits into the curriculum. Supplemental resources include lesson plans and a handout with a grid for showing the relationship between all possible angles that occur when parallel lines are cut by a transversal. Copyright 2005 Eisenhower National Clearinghouse

Shodor Education Foundation

2004-01-01

12

Angles  

NSDL National Science Digital Library

This lesson is designed to introduce students to different types of angles including acute, obtuse, and right. The lesson also introduces ways to compare angles such as alternate interior, corresponding, and many others. This lesson provides links to discussions and activities related to angles as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2011-05-23

13

Angles  

NSDL National Science Digital Library

In this activity, students practice comparing angles when a transversal intersects two parallel lines. This activity allows students to explore the vocabulary used when comparing angles (e.g., alternate, same-side, interior, corresponding, etc.). This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

14

Review of weak mixing angle results at SLC and LEP  

SciTech Connect

In this paper, the authors review recent precise measurements of the weak mixing angle by the SLD experiment at SLC and by the ALEPH, DELPHI, L3, and OPAL experiments at LEP. If they assume that the Minimal Standard Model provides a complete description of the quark and lepton couplings to the Z boson, they find sin{sup 2} {theta}{sub W}{sup eff} = 0.23143 {+-} 0.00028. If this assumption is relaxed to apply to lepton couplings only, they find sin{sup 2}{theta}{sub W}{sup eff} = 0.23106 {+-} 0.00035. They compare these results with other precision electroweak tests.

Woods, M.

1995-10-01

15

Impact of Footprint Diameter and Off-Nadir Pointing on the Precision of Canopy Height Estimates from Spaceborne Lidar  

NASA Technical Reports Server (NTRS)

A spaceborne lidar mission could serve multiple scientific purposes including remote sensing of ecosystem structure, carbon storage, terrestrial topography and ice sheet monitoring. The measurement requirements of these different goals will require compromises in sensor design. Footprint diameters that would be larger than optimal for vegetation studies have been proposed. Some spaceborne lidar mission designs include the possibility that a lidar sensor would share a platform with another sensor, which might require off-nadir pointing at angles of up to 16 . To resolve multiple mission goals and sensor requirements, detailed knowledge of the sensitivity of sensor performance to these aspects of mission design is required. This research used a radiative transfer model to investigate the sensitivity of forest height estimates to footprint diameter, off-nadir pointing and their interaction over a range of forest canopy properties. An individual-based forest model was used to simulate stands of mixed conifer forest in the Tahoe National Forest (Northern California, USA) and stands of deciduous forests in the Bartlett Experimental Forest (New Hampshire, USA). Waveforms were simulated for stands generated by a forest succession model using footprint diameters of 20 m to 70 m. Off-nadir angles of 0 to 16 were considered for a 25 m diameter footprint diameter. Footprint diameters in the range of 25 m to 30 m were optimal for estimates of maximum forest height (R(sup 2) of 0.95 and RMSE of 3 m). As expected, the contribution of vegetation height to the vertical extent of the waveform decreased with larger footprints, while the contribution of terrain slope increased. Precision of estimates decreased with an increasing off-nadir pointing angle, but off-nadir pointing had less impact on height estimates in deciduous forests than in coniferous forests. When pointing off-nadir, the decrease in precision was dependent on local incidence angle (the angle between the off-nadir beam and a line normal to the terrain surface) which is dependent on the off-nadir pointing angle, terrain slope, and the difference between the laser pointing azimuth and terrain aspect; the effect was larger when the sensor was aligned with the terrain azimuth but when aspect and azimuth are opposed, there was virtually no effect on R2 or RMSE. A second effect of off-nadir pointing is that the laser beam will intersect individual crowns and the canopy as a whole from a different angle which had a distinct effect on the precision of lidar estimates of height, decreasing R2 and increasing RMSE, although the effect was most pronounced for coniferous crowns.

Pang, Yong; Lefskky, Michael; Sun, Guoqing; Ranson, Jon

2011-01-01

16

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.; Molinaro, M.

2014-05-01

17

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

18

Estimating spectral albedo and nadir reflectance through inversion of simple BRDF models with AVHRR/MODIS-like data  

NASA Astrophysics Data System (ADS)

In recent years, many computationally efficient bidirectional reflectance models have been developed to account for angular effects in land remote sensing data, particularly those from the NOAA advanced very high resolution radiometer (AVHRR), polarization and directionality of the Earth's reflectances (POLDER), and the planned EOS moderate-resolution imaging spectrometer (MODIS) and multi-angle imaging spectroradiometer (MISR) sensors. In this study, we assessed the relative ability of 10 such models to predict commonly used remote sensing products (nadir reflectance and albedo). Specifically, we inverted each model with ground-based data from the portable apparatus for rapid acquisition of bidirectional observations of the land and atmosphere (PARABOLA) arranged in subsets representative of satellite sampling geometries. We used data from nine land cover types, ranging from soil to grassland (First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE)) to forest (Boreal Ecosystem-Atmosphere Study (BOREAS)). Retrieved parameters were used in forward model runs to estimate nadir reflectance and spectral albedo over a wide range of solar angles. We rank the models by the accuracy of the estimated products and find results to be strongly dependent on the view azimuth angle range of the inversion data, and less dependent on the spectral band and land cover type. Overall, the nonlinear model of Rahman et al. [993] and the linear kernel-driven RossThickLiSparse model [Wanner et al., 1995] were most accurate. The latter was at least 25 times faster to invert than the former. Interestingly, we found these two models were not able to match the various bidirectional reflectance distribution function (BRDF) shapes as well as other models, suggesting their superior performance lies in their ability to be more reliably inverted with sparse data sets. These results should be useful to those interested in the computationally fast normalization of bidirectional reflectance data and the estimation of radiation flux parameters (albedo, absorbed radiation) over diverse land covers.

Privette, Jeffrey L.; Eck, Thomas F.; Deering, Donald W.

1997-12-01

19

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

20

Determination of Optimum Viewing Angles for the Angular Normalization of Land Surface Temperature over Vegetated Surface.  

PubMed

Multi-angular observation of land surface thermal radiation is considered to be a promising method of performing the angular normalization of land surface temperature (LST) retrieved from remote sensing data. This paper focuses on an investigation of the minimum requirements of viewing angles to perform such normalizations on LST. The normally kernel-driven bi-directional reflectance distribution function (BRDF) is first extended to the thermal infrared (TIR) domain as TIR-BRDF model, and its uncertainty is shown to be less than 0.3 K when used to fit the hemispheric directional thermal radiation. A local optimum three-angle combination is found and verified using the TIR-BRDF model based on two patterns: the single-point pattern and the linear-array pattern. The TIR-BRDF is applied to an airborne multi-angular dataset to retrieve LST at nadir (Te-nadir) from different viewing directions, and the results show that this model can obtain reliable Te-nadir from 3 to 4 directional observations with large angle intervals, thus corresponding to large temperature angular variations. The Te-nadir is generally larger than temperature of the slant direction, with a difference of approximately 0.5~2.0 K for vegetated pixels and up to several Kelvins for non-vegetated pixels. The findings of this paper will facilitate the future development of multi-angular thermal infrared sensors. PMID:25825975

Ren, Huazhong; Yan, Guangjian; Liu, Rongyuan; Li, Zhao-Liang; Qin, Qiming; Nerry, Françoise; Liu, Qiang

2015-01-01

21

PREDICTIVE VALUE OF PROSTATE SPECIFIC ANTIGEN NADIR AFTER SALVAGE CRYOTHERAPY  

Microsoft Academic Search

PurposeWe determined nadir prostate specific antigen (PSA) after salvage cyrotherapy to distinguish patients who are potentially cured from those at risk for subsequent biochemical and biopsy proved failure.

GRAHAM F. GREENE; LOUIS L. PISTERS; SHELLIE M. SCOTT; ANDREW C. VON ESCHENBACH

1998-01-01

22

Versatile Rigid-Fluid Coupling for Incompressible SPH Nadir Akinci  

E-print Network

Versatile Rigid-Fluid Coupling for Incompressible SPH Nadir Akinci University of Freiburg Markus Ihmsen University of Freiburg Gizem Akinci University of Freiburg Barbara Solenthaler ETH Zürich Matthias

Teschner, Matthias

23

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

24

Preliminary results from an airdata enhancement algorithm with application to high-angle-of-attack flight  

NASA Technical Reports Server (NTRS)

A technique was developed to improve the fidelity of airdata measurements during dynamic maneuvering. This technique is particularly useful for airdata measured during flight at high angular rates and high angles of attack. To support this research, flight tests using the F-18 high alpha research vehicle (HARV) were conducted at NASA Ames Research Center, Dryden Flight Research Facility. A Kalman filter was used to combine information from research airdata, linear accelerometers, angular rate gyros, and attitude gyros to determine better estimates of airdata quantities such as angle of attack, angle of sideslip, airspeed, and altitude. The state and observation equations used by the Kalman filter are briefly developed and it is shown how the state and measurement covariance matrices were determined from flight data. Flight data are used to show the results of the technique and these results are compared to an independent measurement source. This technique is applicable to both postflight and real-time processing of data.

Moes, Timothy R.; Whitmore, Stephen A.

1991-01-01

25

Hypofractionated SBRT versus conventionally fractionated EBRT for prostate cancer: comparison of PSA slope and nadir  

PubMed Central

Background Patients with early stage prostate cancer have a variety of curative radiotherapy options, including conventionally-fractionated external beam radiotherapy (CF-EBRT) and hypofractionated stereotactic body radiotherapy (SBRT). Although results of CF-EBRT are well known, the use of SBRT for prostate cancer is a more recent development, and long-term follow-up is not yet available. However, rapid post-treatment PSA decline and low PSA nadir have been linked to improved clinical outcomes. The purpose of this study was to compare the PSA kinetics between CF-EBRT and SBRT in newly diagnosed localized prostate cancer. Materials/methods 75 patients with low to low-intermediate risk prostate cancer (T1-T2; GS 3?+?3, PSA?70.2 Gy, <76 Gy) to the prostate only, were identified from a prospectively collected cohort of patients treated at the University of California, San Francisco (1997–2012). Patients were excluded if they failed therapy by the Phoenix definition or had less than 1 year of follow-up or <3 PSAs. 43 patients who were treated with SBRT to the prostate to 38 Gy in 4 daily fractions also met the same criteria. PSA nadir and rate of change in PSA over time (slope) were calculated from the completion of RT to 1, 2 and 3 years post-RT. Results The median PSA nadir and slope for CF-EBRT was 1.00, 0.72 and 0.60 ng/ml and -0.09, -0.04, -0.02 ng/ml/month, respectively, for durations of 1, 2 and 3 years post RT. Similarly, for SBRT, the median PSA nadirs and slopes were 0.70, 0.40, 0.24 ng and -0.09, -0.06, -0.05 ng/ml/month, respectively. The PSA slope for SBRT was greater than CF-EBRT (p?nadir was significantly lower for SBRT when compared to EBRT for years 2 and 3 (p?nadir and greater rate of decline in PSA 2 and 3 years following completion of RT than with CF-EBRT, consistent with delivery of a higher bioequivalent dose. Although follow-up for SBRT is limited, the improved PSA kinetics over CF-EBRT are promising for improved biochemical control. PMID:24484652

2014-01-01

26

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

27

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

28

An evaluation of the exposure in nadir observation of the JEM-EUSO mission  

NASA Astrophysics Data System (ADS)

We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme Universe Space Observatory, on-board the Japanese Experiment Module of the International Space Station. Designed as a mission to explore the extreme energy Universe from space, JEM-EUSO will monitor the Earth's nighttime atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by ultra-high energy cosmic rays. In the present work, we discuss the particularities of space-based observation and we compute the annual exposure in nadir observation. The results are based on studies of the expected trigger aperture and observational duty cycle, as well as, on the investigations of the effects of clouds and different types of background light. We show that the annual exposure is about one order of magnitude higher than those of the presently operating ground-based observatories.

Adams, J. H.; Ahmad, S.; Albert, J.-N.; Allard, D.; Ambrosio, M.; Anchordoqui, L.; Anzalone, A.; Arai, Y.; Aramo, C.; Asano, K.; Ave, M.; Barrillon, P.; Batsch, T.; Bayer, J.; Belenguer, T.; Bellotti, R.; Berlind, A. A.; Bertaina, M.; Biermann, P. L.; Biktemerova, S.; Blaksley, C.; B?eçki, J.; Blin-Bondil, S.; Blümer, J.; Bobik, P.; Bogomilov, M.; Bonamente, M.; Briggs, M. S.; Briz, S.; Bruno, A.; Cafagna, F.; Campana, D.; Capdevielle, J.-N.; Caruso, R.; Casolino, M.; Cassardo, C.; Castellini, G.; Catalano, O.; Cellino, A.; Chikawa, M.; Christl, M. J.; Connaughton, V.; Cortés, J. F.; Crawford, H. J.; Cremonini, R.; Csorna, S.; D'Olivo, J. C.; Dagoret-Campagne, S.; de Castro, A. J.; De Donato, C.; de la Taille, C.; del Peral, L.; Dell'Oro, A.; De Pascale, M. P.; Di Martino, M.; Distratis, G.; Dupieux, M.; Ebersoldt, A.; Ebisuzaki, T.; Engel, R.; Falk, S.; Fang, K.; Fenu, F.; Fernández-Gómez, I.; Ferrarese, S.; Franceschi, A.; Fujimoto, J.; Galeotti, P.; Garipov, G.; Geary, J.; Giaccari, U. G.; Giraudo, G.; Gonchar, M.; González Alvarado, C.; Gorodetzky, P.; Guarino, F.; Guzmán, A.; Hachisu, Y.; Harlov, B.; Haungs, A.; Hernández Carretero, J.; Higashide, K.; Iguchi, T.; Ikeda, H.; Inoue, N.; Inoue, S.; Insolia, A.; Isgrò, F.; Itow, Y.; Joven, E.; Judd, E. G.; Jung, A.; Kajino, F.; Kajino, T.; Kaneko, I.; Karadzhov, Y.; Karczmarczyk, J.; Katahira, K.; Kawai, K.; Kawasaki, Y.; Keilhauer, B.; Khrenov, B. A.; Kim, Jeong-Sook; Kim, Soon-Wook; Kim, Sug-Whan; Kleifges, M.; Klimov, P. A.; Ko, S. H.; Kolev, D.; Kreykenbohm, I.; Kudela, K.; Kurihara, Y.; Kuznetsov, E.; La Rosa, G.; Lee, J.; Licandro, J.; Lim, H.; López, F.; Maccarone, M. C.; Mannheim, K.; Marcelli, L.; Marini, A.; Martin-Chassard, G.; Martinez, O.; Masciantonio, G.; Mase, K.; Matev, R.; Maurissen, A.; Medina-Tanco, G.; Mernik, T.; Miyamoto, H.; Miyazaki, Y.; Mizumoto, Y.; Modestino, G.; Monnier-Ragaigne, D.; Morales de los Ríos, J. A.; Mot, B.; Murakami, T.; Nagano, M.; Nagata, M.; Nagataki, S.; Nakamura, T.; Nam, J. W.; Nam, S.; Nam, K.; Napolitano, T.; Naumov, D.; Neronov, A.; Nomoto, K.; Ogawa, T.; Ohmori, H.; Olinto, A. V.; Orlea?ski, P.; Osteria, G.; Pacheco, N.; Panasyuk, M. I.; Parizot, E.; Park, I. H.; Pastircak, B.; Patzak, T.; Paul, T.; Pennypacker, C.; Peter, T.; Picozza, P.; Pollini, A.; Prieto, H.; Reardon, P.; Reina, M.; Reyes, M.; Ricci, M.; Rodríguez, I.; Rodríguez Frías, M. D.; Ronga, F.; Rothkaehl, H.; Roudil, G.; Rusinov, I.; Rybczy?ski, M.; Sabau, M. D.; Sáez Cano, G.; Saito, A.; Sakaki, N.; Sakata, M.; Salazar, H.; Sánchez, S.; Santangelo, A.; Santiago Crúz, L.; Sanz Palomino, M.; Saprykin, O.; Sarazin, F.; Sato, H.; Sato, M.; Schanz, T.; Schieler, H.; Scotti, V.; Scuderi, M.; Segreto, A.; Selmane, S.; Semikoz, D.; Serra, M.; Sharakin, S.; Shibata, T.; Shimizu, H. M.; Shinozaki, K.; Shirahama, T.; Siemieniec-Ozieb?o, G.; Silva López, H. H.; Sledd, J.; S?omi?ska, K.; Sobey, A.; Sugiyama, T.; Supanitsky, D.; Suzuki, M.; Szabelska, B.; Szabelski, J.; Tajima, F.; Tajima, N.; Tajima, T.; Takahashi, Y.; Takami, H.; Takeda, M.; Takizawa, Y.; Tenzer, C.; Tibolla, O.; Tkachev, L.; Tomida, T.; Tone, N.; Trillaud, F.; Tsenov, R.; Tsuno, K.; Tymieniecka, T.; Uchihori, Y.; Vaduvescu, O.; Valdés-Galicia, J. F.; Vallania, P.; Valore, L.; Vankova, G.; Vigorito, C.; Villaseñor, L.; von Ballmoos, P.; Wada, S.; Watanabe, J.; Watanabe, S.; Watts, J.; Weber, M.; Weiler, T. J.; Wibig, T.; Wiencke, L.; Wille, M.; Wilms, J.; W?odarczyk, Z.; Yamamoto, T.; Yamamoto, Y.; Yang, J.; Yano, H.; Yashin, I. V.; Yonetoku, D.; Yoshida, K.; Yoshida, S.; Young, R.; Zamora, A.; Zuccaro Marchi, A.

2013-04-01

29

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

30

Reprinted from D. Scott Linthicum Nadir R. Farid  

E-print Network

Reprinted from D. Scott Linthicum Nadir R. Farid Editors Anti-Idiotypes, Receptors, and Molecular: A Speculation on the Structure of the Putative Idiotypic Network W. LOUIS CLEVELAND Introduction The clonal.e., idiotype-anti-idiotype (Id-anti-Id) interactions. On the basis of this ex pectation, Jerne constructed

Cleveland, William Louis

31

Piecewise linear car-following modeling Nadir Farhi  

E-print Network

Piecewise linear car-following modeling Nadir Farhi Universit´e Paris-Est, IFSTTAR, GRETTIA, F-93166 Noisy-le-Grand, France. Abstract We present a traffic model that extends the linear car-time car-dynamics describing the traffic on a 1-lane road without passing is interpreted as a dynamic

Boyer, Edmond

32

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

33

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

34

Angles, Angles and More Angles!  

NSDL National Science Digital Library

Test Your Angle Knowledge! Angles Telescope Star Gazing Help diget to fill up his scrapbook of stars by using his telescope and pointting at each planet during the night! But make sure you hurry before the sun comes up! Shoot The Space Ship Angles Game Try and figure out which angle you need to use to shoot down the aliens spaceship! ...

Miss Smith

2011-03-23

35

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

SciTech Connect

Based on atomistic molecular dynamics (MD) simulations, the small angle neutron scattering (SANS) intensity behavior of a single generation-4 (G4) polyelectrolyte polyamidoamine (PAMAM) 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 which provides a link between the neutron scattering experiment and MD computation. The simulations enable scattering calculations of not only the hydrocarbons, but also the contribution to the scattering length density fluctuations caused by structured, confined water within the dendrimer. Based on our computational results, we question the validity of using radius of gyration RG for microstructure characterization of a polyelectrolyte dendrimer from the scattering perspective.

Chen, Wei-Ren [ORNL; Do, Changwoo [ORNL; Hong, Kunlun [ORNL; Liu, Emily [Rensselaer Polytechnic Institute (RPI); Liu, Yun [National Institute of Standards and Technology (NIST); Porcar, L. [National Institute of Standards and Technology (NIST); Smith, Gregory Scott [ORNL; Wu, Bin [ORNL; Egami, T [University of Tennessee, Knoxville (UTK); Smith, Sean C [ORNL

2012-01-01

36

Early results of a posterolateral polyaxial angle-stable plate for tibiotalocalcaneal arthrodesis.  

PubMed

Tibiotalocalcaneal arthrodesis is still considered the reference standard therapy for salvage of severe osteoarthritic deformities of the ankle and hindfoot. Because of the unique anatomy and biomechanics of the ankle, even minor injuries can progress to end-stage osteoarthritis over time. This can be debilitating to patients' general health and physiologic ambulation. Arthrodesis aims to correct the misalignment and should comply with Glissan's principles (i.e., maintenance of permanent stability and sound compression between the fused elements). Several different surgical techniques have been described in the international medical literature. Intramedullary nails can create and maintain a stable condition but lack the necessary compression. Screw fixation can generate compression but might not yield enough stability until sound union has been achieved. In the present study, we report the early results of an innovative posterolateral polyaxial angle-stable plate that combines the features that address all the principles of arthrodesis in 1 device. PMID:25435007

Heck, Benedikt A; Schenk, Uwe; Benali, Youssef; Stahl, Jens-Peter

2015-01-01

37

PITCH-ANGLE SCATTERING: RESONANCE VERSUS NONRESONANCE, A BASIC TEST OF THE QUASILINEAR DIFFUSIVE RESULT  

SciTech Connect

Due to the very broad range of the scales available for the development of turbulence in space and astrophysical plasmas, the energy at the resonant scales of wave-particle interaction often constitutes only a tiny fraction of the total magnetic turbulent energy. Despite the high efficiency of resonant wave-particle interaction, one may therefore question whether resonant interaction really is the determining interaction process between particles and turbulent fields. By evaluating and comparing resonant and nonresonant effects in the frame of a quasilinear calculation, the dominance of resonance is here put to the test. By doing so, a basic test of the classical resonant quasilinear diffusive result for the pitch-angle scattering of charged energetic particles is also performed.

Ragot, B. R. [Helio Research, P.O. Box 1414, Nashua, NH 03061 (United States)

2012-01-01

38

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

39

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

40

CLINICAL RESULTS WITH THE TRABECTOME, A NOVEL SURGICAL DEVICE FOR TREATMENT OF OPEN-ANGLE GLAUCOMA  

PubMed Central

Purpose To describe treatment outcomes after Trabectome surgery in an initial series of 101 patients with open-angle glaucoma. Methods A 19-gauge microelectrosurgical device enabled ab interno removal of a strip of trabecular meshwork and inner wall of Schlemm’s canal under gonioscopic control with continual infusion and foot-pedal control of aspiration and electrosurgery. A smooth, pointed ceramic-coated insulating footplate was inserted into Schlemm’s canal to act as a guide within the canal and to protect adjacent structures from mechanical or heat injury during ablation of a 30- to 90-degree arc of angle tissue. Results Mean preoperative intraocular pressure (IOP) in the initial 101 patients was 27.6 ± 7.2 mm Hg. Thirty months postoperatively, mean IOP was 16.3 ± 3.3 mm Hg (n = 11). The mean percentage drop over the whole course of follow-up was 40%. At all times postoperatively, the absolute and percent decrease in IOP from preoperative levels were statistically significant (paired t test, P < .0001). Overall success (IOP ? 21 mm Hg with or without medications and no subsequent surgery) was 84%. Nine eyes subsequently underwent trabeculectomy, two others had IOP greater than 21 mm Hg in spite of resuming topical medications, and the rest of the patients either refused to resume medications or were still in the 1-month postoperative period without medications (total failure rate including trabeculectomies, 16/101 = 16%). Intraoperative reflux bleeding occurred in 100% of cases. Complications have been minimal and not vision-threatening. Conclusions The Trabectome facilitates minimally invasive and effective glaucoma surgery, which spares the conjunctiva and does not preclude subsequent standard filtering procedures. PMID:17471324

Minckler, Don; Baerveldt, George; Ramirez, Marina Alfaro; Mosaed, Sameh; Wilson, Richard; Shaarawy, Tarek; Zack, Barend; Dustin, Laurie; Francis, Brian

2006-01-01

41

Tropospheric column amount of ozone retrieved from SCIAMACHY limb-nadir-matching observations  

NASA Astrophysics Data System (ADS)

Tropospheric ozone (O3), has two main sources: transport from the stratosphere and photochemical production in the troposphere. It plays important roles in atmospheric chemistry and climate change. Its amount and destruction are being modified by anthropogenic activity. Global measurements are needed to test our understanding of its sources and sinks. In this paper, we describe the retrieval of tropospheric O3 columns (TOCs) from the combined limb and nadir observations (hereinafter referred to as limb-nadir-matching (LNM)) of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument, which flew as part of the payload onboard the European Space Agency (ESA) satellite Envisat (2002-2012). The LNM technique used in this study is a residual approach that subtracts stratospheric O3 columns (SOCs), retrieved from the limb observations, from the total O3 columns (TOZs), derived from the nadir observations. The technique requires accurate knowledge of the SOCs, TOZs, tropopause height, and their associated errors. The SOCs were determined from the stratospheric O3 profiles retrieved in the Hartley and Chappuis bands from SCIAMACHY limb scattering measurements. The TOZs were also derived from SCIAMACHY measurements, but in this case from the nadir viewing mode using the Weighting Function Differential Optical Absorption Spectroscopy (WFDOAS) technique in the Huggins band. Comparisons of the TOCs from SCIAMACHY and collocated measurements from ozonesondes in both hemispheres between January 2003 and December 2011 show agreement to within 2-5 DU (1 DU = 2.69 × 1016 molecules cm-2). TOC values from SCIAMACHY have also been compared to the results from the Tropospheric Emission Spectrometer (TES) and from the LNM technique exploiting Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) data (hereinafter referred to as OMI/MLS). All compared data sets agree within the given data product error range and exhibit similar seasonal variations, which, however, differ in amplitude. The spatial distributions of tropospheric O3 in the SCIAMACHY LNM TOC product show characteristic variations related to stratosphere-troposphere exchange (STE) processes, anthropogenic activities and biospheric emissions.

Ebojie, F.; von Savigny, C.; Ladstätter-Weißenmayer, A.; Rozanov, A.; Weber, M.; Eichmann, K.-U.; Bötel, S.; Rahpoe, N.; Bovensmann, H.; Burrows, J. P.

2014-07-01

42

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

43

Precipitation measurement using SIR-C: A feasibility study. Investigation at nadir  

NASA Technical Reports Server (NTRS)

The most significant limitation of the imaging SAR in rain measurements is the ground return coupled to the rain cell. Here we report a study of the possibility of using the X-SAR and the C-band channel of SIR-C for rain measurement. Earlier signal-to-clutter calculations rule out the use of X-SAR at steeper off-vertical angles of incidence (i.e., 20 less than theta less than 50). Only rain rates greater than 30 mm/hr at angles of incidence greater than 60 degrees showed good signal-to-clutter ratio (SCR). This study involved calculations at vertical incidence. There is adequate signal-to-noise ratio (SNR) at vertical incidence, but the presence of high-range side-lobe levels leads to small SCR for measurement over oceans at both X and C bands. For larger rain thickness (greater than two km), the SCR gets better and smaller rain rates (greater than 10 mm/hr) can be measured. However, rain measurements over forests seem to be feasible at nadir even for smaller rain thickness (less than two km). We conclude that X band may be usable over the forest at vertical incidence to measure rain rates greater than five mm/hr even for shallow rain thickness and over ocean for large rain thickness.

Ahamad, Atiq; Moore, Richard K.

1993-01-01

44

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

45

TES/Aura L2 Methanol (MTL) Nadir (TL2MTLN)  

Atmospheric Science Data Center

TES/Aura L2 Methanol (MTL) Nadir (TL2MTLN) News:  TES News ... 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 ...

2015-02-04

46

TES/Aura L2 Methanol (MTL) Lite Nadir (TL2MTLLN)  

Atmospheric Science Data Center

TES/Aura L2 Methanol (MTL) Lite Nadir (TL2MTLLN) News:  TES News ... Level:  L2 Instrument:  TES/Aura L2 Methanol Spatial Coverage:  5.3 km nadir Spatial ... OPeNDAP Access:  OPeNDAP Parameters:  Methanol Order Data:  Reverb:   Order Data ...

2015-03-11

47

TES/Aura L2 Methanol (MTL) Nadir (TL2MTLNS)  

Atmospheric Science Data Center

TES/Aura L2 Methanol (MTL) Nadir (TL2MTLNS) News:  TES News ... 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 ...

2015-02-04

48

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

Atmospheric Science Data Center

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

2015-01-30

49

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

Atmospheric Science Data Center

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

2015-01-30

50

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

51

Wide-angle high-resolution line-imager prototype flight test results.  

PubMed

A single-channel prototype pushbroom imager has been developed to the specifications required for forestry remote-sensing applications and for mapping. It is based on a commercially available 6000-element linear array for which a special wide-angle, high modulation transfer function lens was designed and fabricated. The test was flown aboard a twin-engine jet aircraft. The sensor has produced high-quality imagery with pixel sizes down to 25 cm. PMID:20725313

Neville, R A; Marois, R; Schwarz, J W; Till, S M

1992-06-20

52

Three-dimensional limited-angle microtomography of blood cells: experimental results  

Microsoft Academic Search

Tomographic measurements of the 3D refractive index spatial distribution within optically transparent phase samples with computerized interferometric microscopes are proposed. Phase shifting interferometric microtomography applications for the 3D image reconstruction of the blood cells are represented. The immersion 100x, N.A. equals 1.25 objective was used to increase the spatial resolution and observation angle range to 90 degree. ART, combined ART

Gennady G. Levin; Gennady N. Vishnyakov; Constantin S. Zakarian; Alexey V. Likhachov; Valery V. Pickalov; Gennady I. Kozinets; Julia K. Novoderzhkina; Elena A. Streletskaya

1998-01-01

53

Treatment of Distal Lower Leg Fractures: Results with Fixed-Angle Plate Osteosynthesis  

Microsoft Academic Search

\\u000a Abstract\\u000a   Twenty-five patients with closed distal tibial fractures were treated with a fixed-angle (locked) plate osteosynthesis. The\\u000a study period was from 1.1.06 to 31.12.07. According to AO classification, there were three A1, eight A2, nine A3, one B2,\\u000a two C1, and two C3 fractures. All patients had a follow up examination after an average of 16.6 months. Complications included\\u000a a

Maximilian Faschingbauer; Benjamin Kienast; Arndt P. Schulz; Rudolf Vukelic; Jan Meiners

2009-01-01

54

Line tension approaching a first-order wetting transition: Experimental results from contact angle measurements  

NASA Astrophysics Data System (ADS)

The line tension values of n-octane and 1-octene on a hexadecyltrichlorosilane coated silicon wafer, are determined by contact angle measurements at temperatures near a first-order wetting transition Tw. It is shown experimentally that the line tension changes sign as the temperature increases toward Tw in agreement with a number of theoretical predictions. A simple phenomenological model possessing a repulsive barrier at l0=5.1+/-0.2 nm and a scale factor of B=78+/-6 provides a quantitative description of the experiments.

Wang, J. Y.; Betelu, S.; Law, B. M.

2001-03-01

55

Backscattering enhancement for Marshall-Palmer distributed rains for a W-band nadir-pointing radar with a finite beam width  

NASA Technical Reports Server (NTRS)

In this paper, we expand the previous theory to be applied to a generic drop size distribution with spheroidal raindrops including spherical raindrops. Results will be used to discuss the multiple scattering effects on the backscatter measurements acquired by a W-band nadir-pointing radar.

Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood; Oguchi, Tomohiro

2005-01-01

56

Remote sounding of gravity waves with satellite limb and nadir techniques  

NASA Astrophysics Data System (ADS)

Gravity waves (GWs) have a profound impact on Earth's weather and climate. Generated mostly from flow over topography, convection and jet stream instability, these waves can break and produce substantial drag forces and turbulent mixing at various altitudes, processes which are unresolved yet and need to be represented in large-scale numerical models. However, observational guidance on these representations remains lacking, particularly from a global point of view. Recent improvements in satellite measurements have demonstrated great potential for mapping GWs globally. In this paper we study GWs resolved by passive microwave radiances acquired from limb and nadir sounding sensors: MLS (Microwave Limb Sounder) on NASA's UARS (Upper Atmosphere Research Satellite) and AMSU-A (Advanced Microwave Sounding Unit-A) on NOAA's operational satellites. In a case study for January 2003, we observe two strong mountain wave events in AMSU-A raw radiances, respectively, over southern Scandinavia on January 14-16 and over southern Greenland on January 31. Both events were forecast operationally by NRL's Mountain Wave Forecast Model during NASA's second SAGE III Ozone Loss and Validation Experiment (SOLVE2), and used to plan DC-8 flights on January 14 to measure wave-induced polar stratospheric clouds. In both events waves propagate from the tropopause to the upper stratosphere showing horizontal wavelengths of 400-500 km. These wave features are consistent with archived T511L60 forecast fields from the European Center for Medium Range Forecasts (ECMWF) and T239L54 hindcasts using a high-altitude research version of the Navy Operational Global Atmospheric Prediction System (NOGAPS-ALPHA). Our studies indicate that both MLS and AMSU-A techniques have detectable sensitivity to temperature perturbations induced by stratospheric GWs. For AMSU-A near-limb viewing angles, the climatology of GW variances is very similar to what was observed by MLS. AMSU-A has better horizontal resolution at nadir views, on one hand, which enables it to resolve short horizontal wavelength orographic GWs forced by topography as small as some sub-Antarctic islands. On the other hand, limb sounders like MLS can provide better sensitivity to tilted wave structures, which can be used to infer important information on wave propagation directions.

Wu, D. L.; Eckermann, S. D.; Coy, L.; Jiang, J. H.; Lawrence, B.

57

Publications Angling, Angling Records,  

E-print Network

Publications Angling, Angling Records, and Game Fish Conservation The 1982 edition of "World Record Game Fishes," published by the Inter- national Game Fish Association, 3000 East Las alas Boulevard, Fort Lauder- dale, FL 33316, continues to grow as an important reference work for the serious angler

58

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

59

NADIR: A prototype system for detecting network and file system abuse  

SciTech Connect

This paper describes the design of a prototype computer misuse detection system for the Los Alamos Notional Laboratory`s Integrated Computing Network (ICN). This automated expert system, the Network Anomaly Detection and Intrusion Reporter (NADIR), streamlines and supplements the manual audit record review traditionally performed by security auditors. NADIR compares network activity, as summarized in weekly profiles of individual users and the ICN as a whole, against expert rules that define security policy, improper or suspicious behavior, and normal user activity. NADIR reports suspicious behavior to security auditors and provides tools to aid in follow-up investigations. This paper describes analysis by NADIR of two types of ICN activity: user authentication and access control, and mass file storage. It highlights system design issues of data handling, exploiting existing auditing systems, and performing audit analysis at the network level.

Hochberg, J.G.; Jackson, K.A.; Stallings, C.A.; McClary, J.F.; DuBois, D.H.; Ford, J.R.

1992-10-01

60

NADIR: A prototype system for detecting network and file system abuse  

SciTech Connect

This paper describes the design of a prototype computer misuse detection system for the Los Alamos Notional Laboratory's Integrated Computing Network (ICN). This automated expert system, the Network Anomaly Detection and Intrusion Reporter (NADIR), streamlines and supplements the manual audit record review traditionally performed by security auditors. NADIR compares network activity, as summarized in weekly profiles of individual users and the ICN as a whole, against expert rules that define security policy, improper or suspicious behavior, and normal user activity. NADIR reports suspicious behavior to security auditors and provides tools to aid in follow-up investigations. This paper describes analysis by NADIR of two types of ICN activity: user authentication and access control, and mass file storage. It highlights system design issues of data handling, exploiting existing auditing systems, and performing audit analysis at the network level.

Hochberg, J.G.; Jackson, K.A.; Stallings, C.A.; McClary, J.F.; DuBois, D.H.; Ford, J.R.

1992-01-01

61

Spatial and Temporal distribution of CO_{2} 4.3-mu m NLTE Emission from nadir VIRTIS-H/Venus Express observations  

NASA Astrophysics Data System (ADS)

Non-Local Thermodynamic Equilibrium (non-LTE) emissions are known to play a key role in the radiative heating and cooling of the Venus mesosphere and lower thermosphere (Dickinson, JAS, 1973; Roldan et al., Icarus, 2000). In the case of the Venusian atmosphere, CO2 vibrational-rotational emissions at 4.3 ?m and 2.7 ?m were predicted to give intense emissions, and since they are originated between 80 and 150 km, their observation might give information on the atmospheric parameters at those altitudes, depending on sensitivity and spectral resolution. The VIRTIS spectrometer on board Venus Express allows for the first time the systematic sounding of these bands in the Venus atmosphere, both in nadir and limb observing geometries. The limb data by VIRTIS has been recently studied by our team (Gilli et al., JGR, 2009; López-Valverde et al., 2010 submitted; Gilli et al., 2010 submitted), focusing on its vertical distribution and the validation of non-LTE models, but an exhaustive study of nadir observations has not been presented so far, except for the detection of gravity waves by García et al. (2008; 2009). In this work, we have used the nadir observations to study the horizontal distribution of the CO2 non-LTE emissions at 4.3 ?m, mainly originated at altitudes about ~110 km. The analyzed dataset comprises the whole nadir measurements with VIRTIS-H (the highest spectral resolution channel) obtained up to September 2009, covering nearly 900 days of observations and more than 140,000 spectra. Similarly to the case of limb data, it was found that the nadir radiance depends not only on the Solar Zenith Angle, but also on the Emission Angle, as predicted by our non-LTE model. After careful radiance averages, the small dispersion found in the mean emission of this band suggests that the Venus lower thermosphere is more stable than expected, with scarce episodes of significant variation during the studied period. Since the spectral resolution of VIRTIS-H allows separating different CO2 isotopic and hot bands, this dataset implies a valuable test for non-LTE models. Therefore, a revision of some key rate coefficients for collisional relaxation of CO2 vibrational energy levels is also carried out, by means of a systematic comparison between radiance ratios measured by VIRTIS-H and the ones obtained with our non-LTE radiative transfer model. Conclusions will be briefly discussed at the meeting.

Peralta, Javier; Ángel López-Valverde, Miguel; Gilli, Gabriella; Drossart, Pierre; Piccioni, Giuseppe

2010-05-01

62

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

63

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. PMID:24606842

2014-01-01

64

Towards 3D Matching of Point Clouds Derived from Oblique and Nadir Airborne Imagery  

NASA Astrophysics Data System (ADS)

Because of the low-expense high-efficient image collection process and the rich 3D and texture information presented in the images, a combined use of 2D airborne nadir and oblique images to reconstruct 3D geometric scene has a promising market for future commercial usage like urban planning or first responders. The methodology introduced in this thesis provides a feasible way towards fully automated 3D city modeling from oblique and nadir airborne imagery. In this thesis, the difficulty of matching 2D images with large disparity is avoided by grouping the images first and applying the 3D registration afterward. The procedure starts with the extraction of point clouds using a modified version of the RIT 3D Extraction Workflow. Then the point clouds are refined by noise removal and surface smoothing processes. Since the point clouds extracted from different image groups use independent coordinate systems, there are translation, rotation and scale differences existing. To figure out these differences, 3D keypoints and their features are extracted. For each pair of point clouds, an initial alignment and a more accurate registration are applied in succession. The final transform matrix presents the parameters describing the translation, rotation and scale requirements. The methodology presented in the thesis has been shown to behave well for test data. The robustness of this method is discussed by adding artificial noise to the test data. For Pictometry oblique aerial imagery, the initial alignment provides a rough alignment result, which contains a larger offset compared to that of test data because of the low quality of the point clouds themselves, but it can be further refined through the final optimization. The accuracy of the final registration result is evaluated by comparing it to the result obtained from manual selection of matched points. Using the method introduced, point clouds extracted from different image groups could be combined with each other to build a more complete point cloud, or be used as a complement to existing point clouds extracted from other sources. This research will both improve the state of the art of 3D city modeling and inspire new ideas in related fields.

Zhang, Ming

65

First results from the Isaac Newton Telescope Wide Angle Survey: The z>5 quasar survey  

E-print Network

We report the first results of an observational program designed to determine the luminosity density of high redshift quasars (z > 5 quasars) using deep multi-colour CCD data. We report the discovery and spectra of 3 i 4.4) quasars, including one with z > 5. At z=5.17, this is the fourth highest redshift quasar currently published. Using these preliminary results we derive an estimate of the M \\rm_B Isaac Newton Telescope as part of the Public Isaac Newton Group Wide Field Survey (WFS). This initial sample of objects is taken from two fields of effective area $\\sim 12.5deg ^2$ from the final $\\sim 100deg ^2$.

R. G. Sharp; R. G. McMahon; M. J. Irwin; S. T. Hodgkin

2001-09-24

66

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

67

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

68

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

69

Prostate-Specific Antigen Nadir Within 12 Months of Prostate Cancer Radiotherapy Predicts Metastasis and Death  

PubMed Central

BACKGROUND The nadir prostate-specific antigen (PSA) at 1 year (nPSA12) was investigated as an early estimate of biochemical and clinical outcome after radiotherapy (RT) alone for localized prostate cancer. METHODS From May 1989 to November 1999, 1000 men received 3D conformal RT alone (median, 76 Gy) with minimum and median follow-up periods of 26 and 58 months, respectively, from the end of treatment. The calculation of PSA doubling time (PSADT) was possible in 657 patients. Multivariate analyses (MVAs) via Cox proportional hazards regression were used to determine the association of nPSA12 to biochemical failure (BF; ASTRO definition), distant metastasis (DM), cause-specific mortality (CSM), and overall mortality (OM). Dichotomization of nPSA12 was optimized by evaluating the sequential model likelihood ratio and P-values. RESULTS In MVA, nPSA12 as a continuous variable was independent of RT dose, T-stage, Gleason score, pretreatment initial PSA, age, and PSADT in predicting for BF, DM, CSM, and OM. Dichotomized nPSA12 (?2 versus >2 ng/mL) was independently related to DM and CSM. Kaplan-Meier 10-year DM rates for nPSA12 ?2 versus >2 ng/mL were 4% versus 19% (P < .0001). CONCLUSIONS nPSA12 is a strong independent predictor of outcome after RTalone for prostate cancer and should be useful in identifying patients at high risk for progression to metastasis and death. PMID:17133416

Alcántara, Pino; Hanlon, Alexandra; Buyyounouski, Mark K.; Horwitz, Eric M.; Pollack, Alan

2007-01-01

70

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

71

Prolonged radiation time and low nadir hemoglobin during postoperative concurrent chemoradiotherapy are both poor prognostic factors with synergistic effect on locally advanced head and neck cancer patients  

PubMed Central

Background Anemia, a common complication of head and neck cancer treatment, is regarded as a poor prognostic factor. We evaluated the impact of low hemoglobin (Hb) levels, measured at different time points, on a consecutive cohort of patients with locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN) who underwent postoperative concurrent chemoradiotherapy (CCRT). Materials and methods From 2002 to 2009, 140 patients were enrolled and reviewed retrospectively. Preoperative (pre-op Hb), pre-CCRT Hb, and nadir Hb during CCRT were measured and recorded. The three Hb parameters were analyzed against several well-established pathologic risk factors and radiation-associated variables. Prognostic impacts were investigated with multivariate analysis by Cox proportional hazards model. Results On Cox regression analysis, significantly higher risk of death was associated with pre-op Hb ?13 g/dL (hazard ratio [HR] =1.8; 95% confidence interval [CI], 1.1–3.1; P=0.023), nadir Hb ?11 g/dL (HR =1.9; 95% CI, 1.1–3.3; P=0.020), radiation treatment time (RTT) >7 weeks (HR =1.9; 95% CI, 1.1–3.3; P=0.022), and multiple positive lymph nodes (HR =2.1; 95% CI, 1.2–3.7; P=0.010), after adjusting for primary tumor site and pathologic lymphovascular invasion. Patients with poor prognosticators including low nadir Hb ?11 g/dL and RTT >7 weeks had a higher risk of death (HR =4.0; 95% CI =1.6–10.2; P=0.004). Conclusion In the treatment setting of LA-SCCHN patients who underwent postoperative CCRT, coexistance of lower nadir Hb during CCRT and prolonged RTT resulted in reduced survival. PMID:25670907

Su, Nai-Wen; Liu, Chung-Ji; Leu, Yi-Shing; Lee, Jehn-Chuan; Chen, Yu-Jen; Chang, Yi-Fang

2015-01-01

72

View angle dependence of MODIS liquid water path retrievals in warm oceanic clouds  

PubMed Central

We investigated the view angle dependence of domain mean Moderate Resolution Imaging Spectroradiometer (MODIS) liquid water path (LWP) and that of corresponding cloud optical thickness, effective radius, and liquid cloud fraction as proxy for plane-parallel retrieval biases. Independent Advanced Microwave Scanning Radiometer–EOS LWP was used to corroborate that the observed variations with sun-view geometry were not severely affected by seasonal/latitudinal changes in cloud properties. Microwave retrievals showed generally small (<10%) cross-swath variations. The view angle (cross-swath) dependence of MODIS optical thickness was weaker in backscatter than forward scatter directions and transitioned from mild ? shape to stronger ? shape as heterogeneity, sun angle, or latitude increased. The 2.2 µm effective radius variations always had a ? shape, which became pronounced and asymmetric toward forward scatter in the most heterogeneous clouds and/or at the lowest sun. Cloud fraction had the strongest and always ?-shaped view angle dependence. As a result, in-cloud MODIS cloud liquid water path (CLWP) showed surprisingly good view angle (cross-swath) consistency, usually comparable to that of microwave retrievals, due to cancelation between optical thickness and effective radius biases. Larger (20–40%) nadir-relative increases were observed in the most extreme heterogeneity and sun angle bins, that is, typically in the polar regions, which, however, constituted only 3–8% of retrievals. The good consistency of MODIS in-cloud CLWP was lost for gridbox mean LWP, which was dominated by the strong cloud fraction increase with view angle. More worryingly, MODIS LWP exhibited significant and systematic absolute increases with heterogeneity and sun angle that is not present in microwave LWP. Key Points Microwave LWP shows small overall and cross-swath variations MODIS in-cloud LWP also shows good view angle consistency in most cases MODIS retrievals show strong overall increase with heterogeneity and sun angle

Horváth, Ákos; Seethala, Chellappan; Deneke, Hartwig

2014-01-01

73

An exact method for computing the nadir values in multiple objective linear programming  

Microsoft Academic Search

In this paper we propose a new method to determine the exact nadir (minimum) criterion values over the efficient set in multiple objective linear programming (MOLP). The basic idea of the method is to determine, for each criterion, the region of the weight space associated with the efficient solutions that have a value in that criterion below the minimum already

Maria João Alves; João Paulo Costa

2009-01-01

74

International Database on Human Capital Quality Nadir ALTINOK and Hatidje MURSELIa*  

E-print Network

International Database on Human Capital Quality Nadir ALTINOK and Hatidje MURSELIa* a IREDU. This allowed us to build indicators of comparable data concerning the quality of human capital in numerous. Keywords: Macroeconomic Data; Education Quality; Human Capital. J.E.L. Classification: C82; I2

Boyer, Edmond

75

ForPeerReview Influence of woody elements of a Norway spruce canopy on nadir reflectance  

E-print Network

ForPeerReview Only Influence of woody elements of a Norway spruce canopy on nadir reflectance) for a simulated Norway spruce canopy was performed at a very high spatial resolution (modelling resolution 0.2 m the Norway spruce canopy as being composed of i) leaves, ii) leaves, trunks and first order branches

Paris-Sud XI, Université de

76

SPOT Mirror and Incidence Angles Consider the Earth centered at E with radius r, a SPOT satellite S at  

E-print Network

SPOT Mirror and Incidence Angles Consider the Earth centered at E with radius r, a SPOT satellite S at altitude a, and a focus point on the Earth's surface F. The mirror angle, in the figure below, describes how far off-nadir the focus point is. For the SPOT HRV sensors it can range from -27 (west) to +27

Janée, Greg

77

Sun and view angle effects on NDVI determination of land cover types in the Brazilian Amazon region with hyperspectral data  

Microsoft Academic Search

Solar zenith and view angle effects on the normalized difference vegetation index (NDVI) of land cover types in the Brazilian Amazon region were analysed. Airborne Hyperspectral Mapper (HYMAP) data were collected in 126 narrow bands (450–2500?nm) with a field of view (FOV) of ±30° from nadir. Data collection was performed initially in two flight lines with solar zenith angles of

F. J. Ponzoni; J. C. N. Epiphanio; B. F. T. Rudorff; A. R. Formaggio

2004-01-01

78

Angle Sums  

NSDL National Science Digital Library

"Examine the angles in a triangle, quadrilateral, pentagon, hexagon, heptagon or octagon and find a relationship between the number of sides and the sum of the interior angles." (Source: 2000-2012 National Council of Teachers of Mathematics)

Illuminations National Council of Teachers of Mathematics

2010-05-20

79

Retrieval of atmospheric CO2 from satellite near-infrared nadir spectra: inter-comparison of different algorithms  

NASA Astrophysics Data System (ADS)

Carbon dioxide is the most important anthropogenic greenhouse gas. Its global increasing concentration in the Earth's atmosphere is the main driver for global warming. However, in spite of its importance, there are still large uncertainties on its global sources and sinks. Satellite measurements, if accurate and precise enough, have the potential to reduce these surface flux uncertainties. At present, there are only two satellite instruments orbiting the Earth which are able to measure the CO2 mixing ratio (XCO2) with large sensitivity also in the boundary layer. These are SCIAMACHY (launched in 2002) and GOSAT (launched in 2009). Worldwide, several teams of scientists are developing algorithms aiming to meet the challenging user requirements. The majority of these groups take part in ESA's climate change initiative (CCI) on greenhouse gases (GHG) where there algorithms stand into competition. Within the presentation, recent inter-comparison results will be shown focusing on global SCIAMACHY nadir observations.

Reuter, M.; Buchwitz, M.; Schneising, O.; Heymann, J.; Bovensmann, H.; Burrows, J. P.

2012-04-01

80

Extending the long-term record of volcanic SO2 emissions with the Ozone Mapping and Profiler Suite nadir mapper  

NASA Astrophysics Data System (ADS)

Uninterrupted, global space-based monitoring of volcanic sulfur dioxide (SO2) emissions is critical for climate modeling and aviation hazard mitigation. We report the first volcanic SO2 measurements using ultraviolet (UV) Ozone Mapping and Profiler Suite (OMPS) nadir mapper data. OMPS was launched on the Suomi National Polar-orbiting Partnership satellite in October 2011. We demonstrate the sensitivity of OMPS SO2 measurements by quantifying SO2 emissions from the modest eruption of Paluweh volcano (Indonesia) in February 2013 and tracking the dispersion of the volcanic SO2 cloud. The OMPS SO2 retrievals are validated using Ozone Monitoring Instrument and Atmospheric Infrared Sounder measurements. The results confirm the ability of OMPS to extend the long-term record of volcanic SO2 emissions based on UV satellite observations. We also show that the Paluweh volcanic SO2 reached the lower stratosphere, further demonstrating the impact of small tropical volcanic eruptions on stratospheric aerosol optical depth and climate.

Carn, S. A.; Yang, K.; Prata, A. J.; Krotkov, N. A.

2015-02-01

81

Versatile Surface Tension and Adhesion for SPH Fluids Nadir Akinci  

E-print Network

such as surface tension and adhesion emerge as a result of inter-molecular forces in a microscopic scale as a result of the impact of a water droplet into a filled container. Our surface tension force allows present a new surface tension force and a new adhesion force. Dif- ferent from the existing work, our

Teschner, Matthias

82

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

83

Angle Practice!  

NSDL National Science Digital Library

How well do you know your angles? Check out these games and put your knowledge to the test! They will stump you if you don't pay close attention to the different angles they give you! Alien Angles! - Use the protractor to guess where the alien has flown away to. If you pick the right spot, you can save all the aliens! Squirt the Dog! Angle practice - Move the hose using different measures of angles to try and squirt the dog. To what degree? - Think you're ready to challenge yourself? Check out ...

Ms. Hume

2012-11-02

84

Validation of Tropospheric Emission Spectrometer (TES) nadir ozone profiles using ozonesonde measurements  

Microsoft Academic Search

We compare Tropospheric Emission Spectrometer (TES) version 2 (V002) nadir ozone profiles with ozonesonde profiles from the Intercontinental Chemical Transport Experiment Ozonesonde Network Study, the World Ozone and Ultraviolet Data Center, the Global Monitoring Division of the Earth System Research Laboratory, and the Southern Hemisphere Additional Ozonesonde archives. Approximately 1600 coincidences spanning 72.5°S-80.3°N from October 2004 to October 2006 are

Ray Nassar; Jennifer A. Logan; Helen M. Worden; Inna A. Megretskaia; Kevin W. Bowman; Gregory B. Osterman; Anne M. Thompson; David W. Tarasick; Shermane Austin; Hans Claude; Manvendra K. Dubey; Wayne K. Hocking; Bryan J. Johnson; Everette Joseph; John Merrill; Gary A. Morris; Mike Newchurch; Samuel J. Oltmans; Françoise Posny; F. J. Schmidlin; Holger Vömel; David N. Whiteman; Jacquelyn C. Witte

2008-01-01

85

Increase in the maximum lift of an airplane wing due to a sudden increase in its effective angle of attack resulting from a gust  

NASA Technical Reports Server (NTRS)

Wind-tunnel tests are described, in which the angle of attack of a wing model was suddenly increased (producing the effect of a vertical gust) and the resulting forces were measured. It was found that the maximum lift coefficient increases in proportion to the rate of increase in the angle of attack. This fact is important for the determination of the gust stresses of airplanes with low wing loading. The results of the calculation of the corrective factor are given for a high-performance glider and a light sport plane of conventional type.

Kramer, Max

1932-01-01

86

Nadir Emissivity Radiative Transfer Model Sensitivity Studies With Applications to Martian Regolith Fine Fraction  

NASA Astrophysics Data System (ADS)

When particles are in near or close contact, they no longer scatter light like single particles. This is problematic for radiative transfer analyses of the photometric properties of surfaces such as the Martian regolith. Despite the community's best efforts, radiative transfer (RT) models are still inadequately predicting laboratory emissivity measurements at nadir, calling even the most fundamental of model assumptions into question [1]. To address these concerns from an empirical standpoint, we present a series of sensitivity studies performed to quantify the effects of single scattering albedo and asymmetry parameter (packed, unpacked cases) on emissivity in the thermal IR (TES, THEMIS, and mini-TES instrument wavenumber ranges) for micron-sized alpha quartz dust grains. By upgrading numerical algorithms from previous works [2, 3], we utilize hybrid solutions (Mie theory + discrete ordinates RT algorithm [4]) to calculate theoretical nadir emissivity values. We demonstrate that assumptions about the scatterer itself, rather than the machinery of the RT method used, constitute the most crucial aspect of modeling nadir emissivity values. This work is supported through NASA MDAP (MJW, KMP). [1] Piatek, J. L., et al. (2003) AAS-DPS #35, #05.04. [2] Moersch, J. E., & Christensen, P. R. (1995) JGR, 100, E4, 7465-7477. [3] Wald, A. E., & Salisbury, J. W. (1995) JGR, 100, B12, 24665-24675. [4] Stamnes, K., et al. (1988) Appl. Opt., 27, 2502-2509.

Pitman, K. M.; Wolff, M. J.; Clayton, G. C.

2004-11-01

87

VIRTIS-M-IR nadir and limb observations: variability of the O2(a1?) nightglow spots  

NASA Astrophysics Data System (ADS)

Individual nadir and limb VIRTIS-M-IR at 1.27 ?m show that the O2(a1 ?) nightglow emission is highly variable. This variability is observed spatially, but also in term of intensity and altitude of the emitting layer over time. Apparent wind velocities have been deduced from the nadir observations, as well as the efolding times. Limb observations show that an increase of the emitting layer altitude is observed near the cold collar region.

Soret, L.; Gérard, J.-C.; Piccioni, G.; Drossart, P.

2014-04-01

88

Angles (elementary)  

NSDL National Science Digital Library

This lesson is designed to introduce students to acute, obtuse, and right angles. This lesson provides links to discussions and activities related to angles as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2011-05-23

89

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

90

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

91

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.'

Paul Goldenberg

2011-06-09

92

SGR 0418+5729: A SMALL INCLINATION ANGLE RESULTING IN A NOT SO LOW DIPOLE MAGNETIC FIELD?  

SciTech Connect

The spin-down behaviors of SGR 0418+5729 are investigated. The pulsar spin-down model of Contopoulos and Spitkovsky is applied to SGR 0418+5729. It is shown that SGR 0418+5729 lies below the pulsar death line and its rotation-powered magnetospheric activities may therefore have stopped. The compact star is now spun down by the magnetic dipole moment perpendicular to its rotation axis. Our calculations show that under these assumptions there is the possibility of SGR 0418+5729 having a strong dipole magnetic field, if there is a small magnetic inclination angle. Its dipole magnetic field may be much higher than the characteristic magnetic field. Therefore, SGR 0418+5729 may be a normal magnetar instead of a low magnetic field magnetar.

Tong, H. [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011 (China); Xu, R. X. [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)

2012-09-20

93

Characterisation of a stratospheric sulphate plume from the Nabro volcano using a combination of passive satellite measurements in nadir and limb geometry  

NASA Astrophysics Data System (ADS)

The eruption of the Nabro volcano (Eritrea), which started on 12 June 2011, caused the introduction of large quantities of SO2 into the lower stratosphere. The subsequently formed sulphate aerosols could be detected for several months following the eruption. It is generally assumed that the formation of sulphate aerosols in the stratosphere takes about a month, but in plumes from explosive eruptions significant amounts of aerosols have been seen to form within a few hours. We show that sulphate aerosols were present in the lower stratosphere within hours of the onset of the eruption of Nabro. Evidence comes from nadir UV Aerosol Index (UVAI) and SO2 measurements by SCIAMACHY, GOME-2 and OMI, and limb aerosol measurements by SCIAMACHY. The sulphate plume displays negative UVAI in the western part of OMI's swath and positive UVAI in the eastern part - an effect that is due to the strong viewing angle dependence of UVAI and can only be caused by a high-altitude (>11 km), non-absorbing (single-scattering albedo >0.97) aerosol plume. For the retrieval of the aerosol profile from limb measurements, the horizontal dimensions and the position of the aerosol plume need to be taken into account, otherwise both extinction and layer height may be underestimated appreciably. By combining nadir SO2 column density and UVAI with limb aerosol profiles, a stratospheric plume from Nabro could be tracked from 13 to 17 June, before the plumes from later, lower-altitude explosions started interfering with the signal. Our findings are in agreement with ground-based lidar and sun-photometer data from an MPLNET/AERONET station in Israel and with data from the satellite-borne CALIOP lidar.

Penning de Vries, M. J. M.; Dörner, S.; Pu??te, J.; Hörmann, C.; Fromm, M. D.; Wagner, T.

2014-03-01

94

Characterisation of a stratospheric sulfate plume from the Nabro volcano using a combination of passive satellite measurements in nadir and limb geometry  

NASA Astrophysics Data System (ADS)

The eruption of the Nabro volcano (Eritrea), which started on 12 June 2011, caused the introduction of large quantities of SO2 into the lower stratosphere. The subsequently formed sulfate aerosols could be detected for several months following the eruption. It is generally assumed that the formation of sulfate aerosols in the stratosphere is a relatively slow process, but in plumes from explosive eruptions significant amounts of aerosols have been seen to form within a few hours. We show that sulfate aerosols were present in the lower stratosphere within hours of the onset of the eruption of Nabro. Evidence comes from nadir UV Aerosol Index (UVAI) and SO2 measurements by SCIAMACHY, GOME-2 and OMI, and limb aerosol measurements by SCIAMACHY. The sulfate plume displays negative UVAI in the western part of OMI's swath and positive UVAI in the eastern part - an effect that is due to the strong viewing angle dependence of UVAI and can only be caused by a high-altitude (>11 km), non-absorbing (single-scattering albedo >0.97) aerosol plume. For the retrieval of the aerosol profile from limb measurements, the horizontal dimensions and the position of the aerosol plume need to be taken into account, otherwise both extinction and layer height may be underestimated appreciably. By combining nadir SO2 column density and UVAI with limb aerosol profiles, a stratospheric plume from Nabro could be tracked from 13 to 17 June, before the plumes from later, lower-altitude explosions started interfering with the signal. Our findings are in agreement with ground-based lidar and sun-photometer data from an MPLNET/AERONET station in Israel and with data from the satellite-borne CALIOP lidar.

Penning de Vries, M. J. M.; Dörner, S.; Pu???te, J.; Hörmann, C.; Fromm, M. D.; Wagner, T.

2014-08-01

95

Ultrafast laser irradiation of spherical nanoparticles: molecular-dynamics results on fragmentation and small-angle scattering  

NASA Astrophysics Data System (ADS)

Using molecular dynamics simulation we study the response of a spherical nanoparticle to a sudden homogeneous energization, such as effected by ultrashort pulse laser irradiation. We consider a Lennard-Jones model system and two different values of the energization. For the smaller one, the sphere expands while a multitude of voids are created inside; the sphere develops finally into an external shell filled with gas and small clusters. For the higher energization, the sphere expands uniformly and no shell structure is formed. An analysis of the pressure generated confirms that in the latter case the pressure is compressive throughout the sphere expansion, while it is temporarily tensile for the lower energization leading to void formation. The final state of both systems shows the fragmentation of the sphere into a multitude of clusters. With increasing fragmentation the cluster distribution becomes shifted to smaller sizes. Simulated small-angle scattering functions of the exploding NP are presented. The distribution of minima allows for an easy determination of the particle size during expansion.

Fahdiran, Riser; Urbassek, Herbert M.

2015-02-01

96

Recent results in the study of heavy-ion elastic scattering at large angles. [180/sup 0/  

SciTech Connect

The observation, a few years ago, of unexpected large cross sections at backward angles in the elastic scattering of mass-asymmetric heavy ion systems gave us hope that we could learn something new and more precise on the properties of the average ion-ion potential. The subsequent observation of broad regular structures in the elastic and inelastic excitation functions near theta/sub cm/ = 180/sup 0/ were also very promising. Numerous models were proposed to explain some or all the observed features. These models can be divided mainly in two groups. Some try to modify directly the average optical potential whereas others associate the observed cross sections to a modification of specific partial waves outside the scope of the optical potential. This separation in two groups is not always clear since as demonstrated adding a Regge pole to a strongly absorbing potential is under some conditions perfectly equivalent to changing the shape of this potential. Similarly the resonances added to an S matrix can be understood as the manifestation of the potential resonances of a completely different optical potential. We describe recent calculations which have been carried on to try to understand the behavior of the data near the barrier.

Barrette, J.; Kahana, S.

1983-01-01

97

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.

98

In-flight Performance and Initial Results of Plasma Energy Angle and Composition Experiment (PACE) on SELENE (Kaguya)  

NASA Astrophysics Data System (ADS)

MAP-PACE (MAgnetic field and Plasma experiment—Plasma energy Angle and Composition Experiment) on SELENE (Kaguya) has completed its ˜1.5-year observation of low-energy charged particles around the Moon. MAP-PACE consists of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). ESA-S1 and S2 measured the distribution function of low-energy electrons in the energy range 6 eV-9 keV and 9 eV-16 keV, respectively. IMA and IEA measured the distribution function of low-energy ions in the energy ranges 7 eV/q-28 keV/q and 7 eV/q-29 keV/q. All the sensors performed quite well as expected from the laboratory experiment carried out before launch. Since each sensor has a hemispherical field of view, two electron sensors and two ion sensors installed on the spacecraft panels opposite each other could cover the full 3-dimensional phase space of low-energy electrons and ions. One of the ion sensors IMA is an energy mass spectrometer. IMA measured mass-specific ion energy spectra that have never before been obtained at a 100 km altitude polar orbit around the Moon. The newly observed data show characteristic ion populations around the Moon. Besides the solar wind, MAP-PACE-IMA found four clearly distinguishable ion populations on the dayside of the Moon: (1) Solar wind protons backscattered at the lunar surface, (2) Solar wind protons reflected by magnetic anomalies on the lunar surface, (3) Reflected/backscattered protons picked-up by the solar wind, and (4) Ions originating from the lunar surface/lunar exosphere.

Saito, Yoshifumi; Yokota, Shoichiro; Asamura, Kazushi; Tanaka, Takaaki; Nishino, Masaki N.; Yamamoto, Tadateru; Terakawa, Yuta; Fujimoto, Masaki; Hasegawa, Hiroshi; Hayakawa, Hajime; Hirahara, Masafumi; Hoshino, Masahiro; Machida, Shinobu; Mukai, Toshifumi; Nagai, Tsugunobu; Nagatsuma, Tsutomu; Nakagawa, Tomoko; Nakamura, Masato; Oyama, Koh-Ichiro; Sagawa, Eiichi; Sasaki, Susumu; Seki, Kanako; Shinohara, Iku; Terasawa, Toshio; Tsunakawa, Hideo; Shibuya, Hidetoshi; Matsushima, Masaki; Shimizu, Hisayoshi; Takahashi, Futoshi

2010-07-01

99

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

100

Ozone ProfilE Retrieval Algorithm 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 set-up 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 year 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) program of ESA. 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 timeseries 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.

2013-10-01

101

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

102

Laser angle sensor development  

NASA Technical Reports Server (NTRS)

Electrical and optical parameters were developed for a two axis (pitch/roll) laser angle sensor. The laser source and detector were mounted in the plenum above the model. Two axis optical distortion measurements of flow characteristics in a 0.3 transonic cryogenic tunnel were made with a shearing interferometer. The measurement results provide a basis for estimating the optical parameters of the laser angle sensor. Experimental and analytical information was generated on model windows to cover the reflector. A two axis breadboard was assembled to evaluate different measurement concepts. The measurement results were used to develop a preliminary design of a laser angle sensor. Schematics and expected performance specifications are included.

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

1980-01-01

103

Remote sensing of trace gases in the midinfrared spectral region from a nadir view.  

PubMed

High-resolution IR remote-sensing measurements from space by means of a nadir-viewing geometry are particularly suited to the detection of trace gases and yield high temporal and horizontal resolutions on a global scale. To identify the potential of such a technique, an extensive feasibility study has been performed. The column amount of some trace gases, namely H(2)O, CH(4), N(2)O, CO, and O(3), may be determined with accuracies of approximately 10%. In addition, some information on the vertical distribution of these species is also possible. Concerning CFC-12, an accuracy of 10%-20% may be expected. Furthermore, it is believed that column amounts can be derived with an accuracy of 20% for HNO(3), and 50% for species like NO(2), OCS, and CFC-11. PMID:20963142

Wetzel, G; Fischer, H; Oelha, H

1995-01-20

104

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

105

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

106

Rain rate estimation from nadir-looking TOPEX\\/POSEIDON microwave radiometer (TMR) for correction of radar altimetric measurements  

Microsoft Academic Search

Atmospheric liquid water, particularly in the form of rain, produces anomalies in the radar altimetric range measurements. Such features are observed as sudden large changes in radar backscatter as a means of identification. To quantify the rain that radar altimetric pulses encounter, the instantaneous rain estimation capability of the nadir looking multichannel microwave radiometer onboard the TOPEX\\/POSEIDON satellite is explored.

Atul Kumar Varma; Rakesh Mohan Gairola; C. M. Kishtawal; P. C. Pandey; K. P. Singh

1999-01-01

107

Satellite calibration using a collocated nadir observation technique: theoretical basis and application to the GMS-5 Pathfinder benchmark period  

Microsoft Academic Search

A collocated nadir observation technique has been used as part of the geostationary meteorological satellite (GMS) pathfinder project and is now employed at the Australian Bureau of Meteorology Research Centre to calibrate the visible infrared spin scan radiometer (VISSR) instrument used on GMS-5. It uses satellite-to-satellite cross calibration to bypass many of the problems inherent in the absolute calibration of

John F. Le Marshall; James J. Simpson; Zhonghai Jin

1999-01-01

108

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

109

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

110

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

111

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

112

Preliminary results for a large angle oblique jet impingement and flow and for the effect of initial conditions on the near field of an axisymmetric jet  

NASA Technical Reports Server (NTRS)

The structure of an axisymmetric jet in the near field is discussed for jet noise and for jet impingment schemes for STOL aircraft. It is inferred from previous studies, and the inference is supported by analysis, that the scale and intensity of the turbulence structure at the jet exit plane are the important boundary conditions which effect the development of the flow in the near field. The techniques to study these effects while maintaining a uniform mean flow and the results which document the range of the initial conditions are presented. The large angle, oblique jet impingment condition is of interest in terms of the jet/flap interaction. Detailed turbulence data can be obtained with the specially constructed facility. The development of the flow and instrumentation system and initial data from the new facility are presented.

Foss, J. F.; Kleis, S. J.

1973-01-01

113

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

114

Triangle Geometry: Angles  

NSDL National Science Digital Library

This interactive math site teaches students about angles and triangles. There are interactive activities for measuring angles, exploring types of angles, and adding angles. By using a Java applet and pictures, a proof of the Pythagorean Theorem is demonstrated.

Math Cove

2007-12-12

115

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.

116

On Orbit Measurement of Response vs. Scan Angle for the Infrared Bands on TRMM/VIRS  

NASA Technical Reports Server (NTRS)

The Visible and Infrared Scanner on the Tropical Rainfall Measuring Mission (TRMM/VIRS) is a whiskbroom imaging radiometer with two reflected solar bands and three emissive infrared bands. All five detectors are on a single cooled focal plane. This configuration necessitated the use of a paddlewheel scan mirror to avoid the effects of focal plane rotation that arise when using a scan mirror that is inclined to its axis of rotation. System radiometric requirements led to the need for protected silver as the mirror surface. Unfortunately, the SiO(x) coatings currently used to protect silver from oxidation introduce a change in reflectance with angle of incidence (AOI). This AOI dependence results in a modulation of system level response with scan angle. Measurement of system response vs. scan angle (RVS) was not difficult for the VIRS reflected solar bands, but attaining the required accuracy for the IR bands in the laboratory was not possible without a large vacuum chamber and a considerable amount of custom designed testing apparatus. Therefore, the decision was made to conduct the measurement on-orbit. On three separate occasions, the TRMM spacecraft was rotated about its pitch axis and, after the nadir view passed over the Earth's limb, the VIRS performed several thousand scans while viewing deep space. The resulting data has been analyzed and the RVS curves generated for the three IR bands are being used in the VIRS radiometric calibration algorithm. This, to our knowledge, the first time this measurement has been made on-orbit. Similar measurements are planned for the EOS-AM and EOS-PM MODIS sensors and are being considered for several systems under development. The VIRS on-orbit results will be compared to VIRS and MODIS system level laboratory measurements, MODIS scan mirror witness sample measurements and modeled data.

Barnes, William L.; Lyu, Cheng-Hsuan; Barnes, Robert A.

1999-01-01

117

Second-Generation Multi-Angle Imaging Spectroradiometer  

NASA Technical Reports Server (NTRS)

A report discusses an early phase in the development of the MISR-2 C, a second, improved version of the Multi-angle Imaging SpectroRadiometer (MISR), which has been in orbit around the Earth aboard NASA's Terra spacecraft since 1999. Like the MISR, the MISR-2 would contain a pushbroom array of nine charge-coupled- device (CCD) cameras one aimed at the nadir and the others aimed at different angles sideways from the nadir. The major improvements embodied in the MISR-2 would be the following: A new folded-reflective-optics design would render the MISR-2 only a third as massive as the MISR. Smaller filters and electronic circuits would enable a reduction in volume to a sixth of that of the MISR. The MISR-2 would generate images in two infrared spectral bands in addition to the blue, green, red, and near-infrared spectral bands of the MISR. Miniature polarization filters would be incorporated to add a polarization-sensing capability. Calibration would be performed nonintrusively by use of a gimbaled tenth camera. The main accomplishment thus far has been the construction of an extremely compact all-reflective-optics CCD camera to demonstrate feasibility.

Macenka, Steven; Hovland, Larry; Preston, Daniel; Zellers, Brian; Downing, Kevin

2004-01-01

118

Generalization of the Euler Angles  

NASA Technical Reports Server (NTRS)

It is shown that the Euler angles can be generalized to axes other than members of an orthonormal triad. As first shown by Davenport, the three generalized Euler axes, hereafter: Davenport axes, must still satisfy the constraint that the first two and the last two axes be mutually perpendicular if these axes are to define a universal set of attitude parameters. Expressions are given which relate the generalized Euler angles, hereafter: Davenport angles, to the 3-1-3 Euler angles of an associated direction-cosine matrix. The computation of the Davenport angles from the attitude matrix and their kinematic equation are presented. The present work offers a more direct development of the Davenport angles than Davenport's original publication and offers additional results.

Bauer, Frank H. (Technical Monitor); Shuster, Malcolm D.; Markley, F. Landis

2002-01-01

119

Refining the Concept of Combining Hyperspectral and Multi-Angle Sensors for Land Surface Applications  

NASA Astrophysics Data System (ADS)

Assessment of leaf and canopy chlorophyll content provides information on plant physiological status; it is related to nitrogen content and hence, photosynthesis process, net primary productivity and carbon budget. In this study, a method is developed for the retrieval of total chlorophyll content (Chlorophyll a+b) per unit leaf and per unit ground area based on improved vegetation structural parameters which are derived using multispectral multi-angle remote sensing data. Structural characteristics such as clumping and gaps within a canopy affect its solar radiation absorption and distribution and impact its reflected radiance acquired by a sensor. One of the main challenges for the remote sensing community is to accurately estimate vegetation structural parameters, which inevitably influence the retrieval of leaf chlorophyll content. Multi-angle optical measurements provide a means to characterize the anisotropy of surface reflectance, which has been shown to contain information on vegetation structural characteristics. Hyperspectral optical measurements, on the other hand, provide a fine spectral resolution at the red-edge, a narrow spectral range between the red and near infra-red spectra, which is particularly useful for retrieving chlorophyll content. This study explores a new refined measurement concept of combining multi-angle and hyperspectral remote sensing that employs hyperspectral signals only in the vertical (nadir) direction and multispectral measurements in two additional (off-nadir) directions within two spectral bands, red and near infra-red (NIR). The refinement has been proposed in order to reduce the redundancy of hyperspectral data at more than one angle and to better retrieve the three-dimensional vegetation structural information by choosing the two most useful angles of measurements. To illustrate that hyperspectral data acquired at multiple angles exhibit redundancy, a radiative transfer model was used to generate off-nadir hyperspectral reflectances. It has been successfully demonstrated that the off-nadir hyperspectral simulations could be closely reconstructed based on the nadir hyperspectral reflectance and off-nadir multi-spectral reflectance in the red and NIR bands. This is shown using the Compact High-resolution Imaging Spectrometer (CHRIS) and Compact Airborne Spectrographic Imager (CASI) data acquired over a forested area in the Sudbury region (Ontario, Canada). Through intensive validation using field data, it is demonstrated that the combination of reflectances at two angles, the hotspot and darkspot, through the Normalized Difference between Hotspot and Darkspot (NDHD) index has the strongest response to changes in vegetation clumping, an important structural component of canopy. Clumping index (O) and Leaf Area Index (LAI) maps are generated based on previous algorithms as well as empirical relationships developed in this study. To retrieve chlorophyll content, inversion of the 5-Scale model is performed by developing Look-Up Tables (LUTs) that are based on the improved structural characteristics developed using multi-angle data. The generated clumping index and LAI maps are used in the LUTs to estimate leaf reflectance. Inversion of the leaf reflectance model, PROSPECT, is further employed to estimate chlorophyll content per unit leaf area. The estimated leaf chlorophyll contents are in good agreement with field-measured values. The refined measurement concept of combining hyperspectral with multispectral multi-angle data provides the opportunity for simultaneous retrieval of vegetation structural and biochemical parameters.

Simic, Anita

120

P-wave velocity structure of the southern Ryukyu margin east of Taiwan: Results from the ACTS wide-angle seismic experiment  

E-print Network

.-S. Liu d , K. McIntosh e , T. Theunissen b a Dep. of Marine Geosciences, IFREMER, Centre de Brest, B Trench Marine seismics Wide-angle seismics Subduction processes An active seismic experiment has been reserved. 1. Introduction and previous work The Philippine Sea Plate (PSP) converges toward the Eurasia

Demouchy, Sylvie

121

Off-nadir antenna bias correction using Amazon rain forest sigma deg data. [Brazil  

NASA Technical Reports Server (NTRS)

The radar response from the Amazon rain forest was studied to determine the suitability of this region for use as a standard target to calibrate a scatterometer like that proposed for the National Ocean Satellite System (NOSS). Backscattering observations made by the SEASAT-1 scatterometer system show the Amazon rain forest to be a homogeneous, azimuthally-isotropic, radar target which is insensitive to polarization. The variation with angle of incidence may be adequately modeled as sigma deg (dB) = alpha theta + beta with typical values for the incidence-angle coefficient from 0.07 dB deg to 0.15 dB/deg. A small diurnal effect occurs, with measurements at sunrise being 0.5 dB to 1 dB higher than the rest of the day. Maximum likelihood estimation algorithms are presented which permit determination of relative bias and true pointing angle for each beam. Specific implementation of these algorithms for the proposed NOSS scatterometer system is also discussed.

Birrer, I. J.; Bracalente, E. M.; Dome, G. J.; Sweet, J.; Berthold, G.; Moore, R. K. (principal investigators)

1981-01-01

122

Off-nadir antenna bias correction using Amazon rain sigma(0) data  

NASA Technical Reports Server (NTRS)

The radar response from the Amazon rain forest was studied to determine the suitability of this region for use as a standard target to calibrate a scatterometer like that proposed for the National Oceanic Satellite System (NOSS). Backscattering observations made by the SEASAT Scatterometer System (SASS) showed the Amazon rain forest to be a homogeneous, azimuthally-isotropic, radar target which was insensitive to polarization. The variation with angle of incidence was adequately modeled as scattering coefficient (dB) = a theta b with typical values for the incidence-angle coefficient from 0.07 to 0.15 dB/deg. A small diurnal effect occurs, with measurements at sunrise being 0.5 dB to 1 dB higher than the rest of the day. Maximum-likelihood estimation algorithms presented here permit determination of relative bias and true pointing angle for each beam. Specific implementation of these algorithms for the proposed NOSS scatterometer system is also discussed.

Birrer, I. J.; Dome, G. J.; Sweet, J.; Berthold, G.; Moore, R. K.

1982-01-01

123

Round-robin evaluation of nadir ozone profile retrievals: methodology and application to MetOp-A GOME-2  

NASA Astrophysics Data System (ADS)

A methodology for the round-robin evaluation and geophysical validation of ozone profile data retrieved from nadir UV backscatter satellite measurements is detailed and discussed, consisting of dataset content studies, information content studies, co-location studies, and comparisons with reference measurements. Within ESA's Climate Change Initiative on ozone (Ozone_cci project), the proposed round-robin procedure is applied to two nadir ozone profile datasets retrieved at KNMI and RAL, using their respective OPERA v1.26 and RAL v2.1 optimal estimation algorithms, from MetOp-A GOME-2 measurements taken in 2008. The ground-based comparisons use ozonesonde and lidar profiles as reference data, acquired by the Network for the Detection of Atmospheric Composition Change (NDACC), Southern Hemisphere Additional Ozonesonde programme (SHADOZ), and other stations of WMO's Global Atmosphere Watch. This direct illustration highlights practical issues that inevitably emerge from discrepancies in e.g. profile representation and vertical smoothing, for which different recipes are investigated and discussed. Several approaches for information content quantification, vertical resolution estimation, and reference profile resampling are compared and applied as well. The paper concludes with compliance estimates of the two GOME-2 ozone profile datasets with user requirements from GCOS and from climate modellers.

Keppens, A.; Lambert, J.-C.; Granville, J.; Miles, G.; Siddans, R.; van Peet, J. C. A.; van der A, R. J.; Hubert, D.; Verhoelst, T.; Delcloo, A.; Godin-Beekmann, S.; Kivi, R.; Stübi, R.; Zehner, C.

2014-11-01

124

PSA Nadir of <0.5 ng/mL Following Brachytherapy for Early-Stage Prostate Adenocarcinoma is Associated With Freedom From Prostate-Specific Antigen Failure  

SciTech Connect

Purpose: Because limited information exists regarding whether the rate or magnitude of PSA decline following brachytherapy predicts long-term clinical outcomes, we evaluated whether achieving a prostate-specific antigen (PSA) nadir (nPSA) <0.5 ng/mL following brachytherapy is associated with decreased PSA failure and/or distant metastasis. Methods and Materials: We retrospectively analyzed our database of early-stage prostate adenocarcinoma patients who underwent brachytherapy, excluding those receiving androgen-deprivation therapy and those with <2 years follow-up. Median and mean pretreatment PSA were 6 ng/mL and 7.16 ng/mL, respectively. By clinical stage, 775 were low risk ({<=}T2a), 126 were intermediate risk (T2b), and 20 were high risk (>T2b). By Gleason score, 840 were low risk ({<=}6), 71 were intermediate risk (7), and 10 were high risk (>7). Patients were treated with brachytherapy only (I-125, n = 779, or Pd-103, n = 47), or brachytherapy + external-beam radiation therapy (n = 95). Median follow-up was 6.3 years. We noted whether nPSA <0.5 ng/mL was achieved and the time to achieve this nadir and tested for associations with pretreatment risk factors. We also determined whether this PSA endpoint was associated with decreased PSA failure or distant metastasis. Results: Absence of high-risk factors in clinical stage ({<=}T2b), Gleason score ({<=}7), and pretreatment PSA ({<=}20 ng/mL) was significantly associated with achieving nPSA <0.5 ng/mL. By Kaplan-Meier analysis, patients achieving nPSA <0.5 ng/mL had significantly higher long-term freedom from biochemical failure (FFBF) than nonresponders (5-year FFBF: 95.2 {+-} 0.8% vs. 71.5 {+-} 6.7%; p < 0.0005). Among responders, those who achieved nPSA <0.5 ng/mL in {<=}5 years had higher FFBF than those requiring >5 years (5-year FFBF: 96.7 {+-} 0.7% vs. 80.8 {+-} 4.6%; p < 0.0005). On multivariate analysis, patients who achieved nPSA <0.5 ng/mL in {<=}5 years had significantly higher FFBF than other patients. Conclusions: Pretreatment risk factors (clinical tumor stage, Gleason score, pretreatment PSA) strongly predict for patients achieving nPSA <0.5 ng/mL following brachytherapy, and this cohort had significantly higher long-term FFBF.

Ko, Eric C. [Department of Radiation Oncology, Mount Sinai Medical Center, New York, NY (United States); Stone, Nelson N. [Department of Radiation Oncology, Mount Sinai Medical Center, New York, NY (United States); Department of Urology, Mount Sinai Medical Center, New York, NY (United States); Stock, Richard G., E-mail: Richard.Stock@mountsinai.org [Department of Radiation Oncology, Mount Sinai Medical Center, New York, NY (United States)

2012-06-01

125

Mapping global seasonal forest background reflectivity with Multi-angle Imaging Spectroradiometer data  

NASA Astrophysics Data System (ADS)

Forest background reflectivities with seasonal and spatial variations are critically important in the estimation of canopy biophysical parameters of the forest canopy. In this paper, seasonal background reflectivity for global forested areas was mapped at 1.1 km resolution using four-scale model and Multi-angle Imaging Spectroradiometer data of the nadir and 45° forward directions. The largest seasonal variation of forest background reflectivities was observed in middle and high latitudes of Northern Hemisphere. The background reflectivity differs between deciduous broadleaf forest and coniferous forest in the near-infrared band and varies with increasing canopy leaf area index. The partial validation of forest background reflectivity with adjacent grassland in the Northern Hemisphere and the comparison of understory leaf area index on leaf appearance day for larch forest in North Asia both indicate the relative reliability of results. The nearly 70% spatial coverage of retrieval with high-quality flags makes it eligible for applications over global coniferous and deciduous broadleaf forest areas.

Jiao, Tong; Liu, Ronggao; Liu, Yang; Pisek, Jan; Chen, Jing M.

2014-06-01

126

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

127

Small Angle Neutron Scattering  

SciTech Connect

Small Angle Neutron Scattering (SANS) probes structural details at the nanometer scale in a non-destructive way. This article gives an introduction to scientists who have no prior small-angle scattering knowledge, but who seek a technique that allows elucidating structural information in challenging situations that thwart approaches by other methods. SANS is applicable to a wide variety of materials including metals and alloys, ceramics, concrete, glasses, polymers, composites and biological materials. Isotope and magnetic interactions provide unique methods for labeling and contrast variation to highlight specific structural features of interest. In situ studies of a material s responses to temperature, pressure, shear, magnetic and electric fields, etc., are feasible as a result of the high penetrating power of neutrons. SANS provides statistical information on significant structural features averaged over the probed sample volume, and one can use SANS to quantify with high precision the structural details that are observed, for example, in electron microscopy. Neutron scattering is non-destructive; there is no need to cut specimens into thin sections, and neutrons penetrate deeply, providing information on the bulk material, free from surface effects. The basic principles of a SANS experiment are fairly simple, but the measurement, analysis and interpretation of small angle scattering data involves theoretical concepts that are unique to the technique and that are not widely known. This article includes a concise description of the basics, as well as practical know-how that is essential for a successful SANS experiment.

Urban, Volker S [ORNL

2012-01-01

128

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

129

Angle closure in younger patients.  

PubMed Central

PURPOSE: Angle-closure glaucoma is rare in children and young adults. Only scattered cases associated with specific clinical entities have been reported. We evaluated the findings in patients in our database aged 40 or younger with angle closure. METHODS: Our database was searched for patients with angle closure who were 40 years old or younger. Data recorded included age at initial consultation; age at the time of diagnosis; gender; results of slit-lamp examination, gonioscopy, and ultrasound biomicroscopy (from 1993 onward); clinical diagnosis; and therapy. Patients with previous incisional surgery were excluded, as were patients with anterior chamber proliferative mechanisms leading to angle closure. RESULTS: Sixty-seven patients (49 females, 18 males) met entry criteria. Mean age (+/- SD) at the time of consultation was 34.4 +/- 9.4 years (range, 3-68 years). Diagnoses included plateau iris syndrome (35 patients), iridociliary cysts (8 patients), retinopathy of prematurity (7 patients), uveitis (5 patients), isolated nanophthalmos (3 patients), relative pupillary block (2 patients), Weill-Marchesani syndrome (3 patients), and 1 patient each with Marfan syndrome, miotic-induced angle closure, persistent hyperplastic primary vitreous, and idiopathic lens subluxation. CONCLUSION: The etiology of angle closure in young persons is different from that in the older population and is typically associated with structural or developmental ocular anomalies rather than relative pupillary block. Following laser iridotomy, these eyes should be monitored for recurrent angle closure and the need for additional laser or incisional surgical intervention. PMID:12545694

Chang, Brian M; Liebmann, Jeffrey M; Ritch, Robert

2002-01-01

130

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

131

Small angle spectrometers: Summary  

SciTech Connect

Aspects of experiments at small angles at the Superconducting Super Collider are considered. Topics summarized include a small angle spectrometer, a high contingency spectrometer, dipole and toroid spectrometers, and magnet choices. (LEW)

Courant, E.; Foley, K.J.; Schlein, P.E.; Rosner, J.; Slaughter, J.; Bromberg, C.; Jones, L.; Garren, A.; Groom, D.; Johnson, D.E.

1986-01-01

132

Angles of Reflection  

NSDL National Science Digital Library

This interactive simulation shows what happens to light when it hits a mirror. The simluation allows the user to change the angle of the incoming or incident light wave and see the corresponding reflected angle.

Michael W. Davidson

2006-06-15

133

Multi-Angle View of the Canary Islands  

NASA Technical Reports Server (NTRS)

A multi-angle view of the Canary Islands in a dust storm, 29 February 2000. At left is a true-color image taken by the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite. This image was captured by the MISR camera looking at a 70.5-degree angle to the surface, ahead of the spacecraft. The middle image was taken by the MISR downward-looking (nadir) camera, and the right image is from the aftward 70.5-degree camera. The images are reproduced using the same radiometric scale, so variations in brightness, color, and contrast represent true variations in surface and atmospheric reflectance with angle. Windblown dust from the Sahara Desert is apparent in all three images, and is much brighter in the oblique views. This illustrates how MISR's oblique imaging capability makes the instrument a sensitive detector of dust and other particles in the atmosphere. Data for all channels are presented in a Space Oblique Mercator map projection to facilitate their co-registration. The images are about 400 km (250 miles)wide, with a spatial resolution of about 1.1 kilometers (1,200 yards). North is toward the top. 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. JPL is a division of the California Institute of Technology.

2000-01-01

134

Retrieving atmospheric dust opacity on Mars by imaging spectroscopy at large angles  

NASA Astrophysics Data System (ADS)

We propose a new method to retrieve the optical depth of Martian aerosols (AOD) from OMEGA and CRISM hyperspectral imagery at a reference wavelength of 1 ?m. Our method works even if the underlying surface is completely made of minerals, corresponding to a low contrast between surface and atmospheric dust, while being observed at a fixed geometry. Minimizing the effect of the surface reflectance properties on the AOD retrieval is the second principal asset of our method. The method is based on the parametrization of the radiative coupling between particles and gas determining, with local altimetry, acquisition geometry, and the meteorological situation, the absorption band depth of gaseous CO2. Because the last three factors can be predicted to some extent, we can define a new parameter ? that expresses specifically the strength of the gas-aerosols coupling while directly depending on the AOD. Combining estimations of ? and top of the atmosphere radiance values extracted from the observed spectra within the CO2 gas band at 2 ?m, we evaluate the AOD and the surface reflectance by radiative transfer inversion. One should note that practically ? can be estimated for a large variety of mineral or icy surfaces with the exception of CO2 ice when its 2 ?m solid band is not sufficiently saturated. Validation of the proposed method shows that it is reliable if two conditions are fulfilled: (i) the observation conditions provide large incidence or/and emergence angles (ii) the aerosols are vertically well mixed in the atmosphere. Experiments conducted on OMEGA nadir looking observations as well as CRISM multi-angular acquisitions with incidence angles higher than 65° in the first case and 33° in the second case produce very satisfactory results. Finally in a companion paper the method is applied to monitoring atmospheric dust spring activity at high southern latitudes on Mars using OMEGA.

Douté, S.; Ceamanos, X.; Appéré, T.

2013-09-01

135

Angles All Around  

NSDL National Science Digital Library

Standard: Identify and measure right, obtuse, and acute angles. This is a two day activity. OBJECTIVE: We have learned about five different types of angles: right, acute, obtuse, straight, and reflex. We have also learned how to use a protractor to measure angles. With this lesson, you will practice what ...

Mrs. Bennett

2011-12-14

136

628 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 52, NO. 1, JANUARY 2014 Zenith/Nadir Pointing mm-Wave Radars  

E-print Network

for the CDR mode. The Simultaneous Transmission and Simultaneous Recep- tion mode (STSR mode or hybrid mode or ZDR mode) is also theoretically analyzed for the case of zenith/nadir pointing radars and, under the assumption of azimuthal symmetry, relations are given to compare measurements obtained at hybrid mode

Ohta, Shigemi

137

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 40, NO. 2, FEBRUARY 2002 515 The Dependence of Nadir Ocean Surface Emissivity on  

E-print Network

The Dependence of Nadir Ocean Surface Emissivity on Wind Vector as Measured With Microwave Radiometer Ngan Tran observations of TOPEX/Po- seidon microwave radiometer (TMR) at 18, 21, and 37 GHz have been col- located/Poseidon microwave radiometer (TMR). I. INTRODUCTION The TOPEX/Poseidon microwave radiometer (TMR) is a three

Ruf, Christopher

138

Multi-Angle Views of the Appalachian Mountains, 6 March 2000  

NASA Technical Reports Server (NTRS)

The true-color image at left is a downward-looking (nadir) view of the eastern United States, stretching from Lake Ontario to northern Georgia, and spanning the Appalachian Mountains. The three images to the right are also in true-color, taken by the forward 45.6-degree, 60.0-degree, and 70.5-degree cameras, respectively, of the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite. As the slant angle increases, the line-of-sight through the atmosphere grows longer, and a pall of haze over the Appalachians becomes progressively more apparent. You can see a similar effect by scanning from near-nadir to the horizon when standing on a mountain top or looking out an airplane window. MISR uses this multi-angle technique to monitor particulate pollution and to distinguish different types of haze. These observations reveal how airborne particles are interacting with sunlight, a measure of their impact on Earth's climate system. The images are about 400 km (250 miles) wide, and the spatial resolution is 1.1 kilometers (1,200 yards). North is toward the top. 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. JPL is a division of the California Institute of Technology.

2000-01-01

139

External Beam Radiotherapy for Clinically Localized Hormone-Refractory Prostate Cancer: Clinical Significance of Nadir Prostate-Specific Antigen Value Within 12 Months  

SciTech Connect

Purpose: To analyze retrospectively the results of external beam radiotherapy for clinically localized hormone-refractory prostate cancer and investigate the clinical significance of nadir prostate-specific antigen (PSA) value within 12 months (nPSA12) as an early estimate of clinical outcomes after radiotherapy. Methods and Materials: Eighty-four patients with localized hormone-refractory prostate cancer treated with external beam radiotherapy were retrospectively reviewed. The total radiation doses ranged from 30 to 76 Gy (median, 66 Gy), and the median follow-up period for all 84 patients was 26.9 months (range, 2.7-77.3 months). Results: The 3-year actuarial overall survival, progression-free survival (PFS), and local control rates in all 84 patients after radiotherapy were 67%, 61%, and 93%, respectively. Although distant metastases and/or regional lymph node metastases developed in 34 patients (40%) after radiotherapy, local progression was observed in only 5 patients (6%). Of all 84 patients, the median nPSA12 in patients with clinical failure and in patients without clinical failure was 3.1 ng/mL and 0.5 ng/mL, respectively. When dividing patients according to low (<0.5 ng/mL) and high ({>=}0.5 ng/mL) nPSA12 levels, the 3-year PFS rate in patients with low nPSA12 and in those with high nPSA12 was 96% and 44%, respectively (p < 0.0001). In univariate analysis, nPSA12 and pretreatment PSA value had a significant impact on PFS, and in multivariate analysis nPSA12 alone was an independent prognostic factor for PFS after radiotherapy. Conclusions: External beam radiotherapy had an excellent local control rate for clinically localized hormone-refractory prostate cancer, and nPSA12 was predictive of clinical outcomes after radiotherapy.

Ogawa, Kazuhiko [Department of Radiology, University of the Ryukyus, Okinawa, Osaka (Japan)], E-mail: kogawa@med.u-ryukyu.ac.jp; Nakamura, Katsumasa [Department of Clinical Radiology, Fukuoka University, Fukuoka (Japan); Sasaki, Tomonari [Department of Radiation Oncology, National Kyushu Center, Fukuoka (Japan); Onishi, Hiroshi [Department of Radiology, Yamanashi University, Yamanashi (Japan); Koizumi, Masahiko [Department of Radiation Oncology, Osaka University, Osaka (Japan); Shioyama, Yoshiyuki [Department of Clinical Radiology, Kyushu University, Fukuoka (Japan); Araya, Masayuki [Department of Radiology, Yamanashi University, Yamanashi (Japan); Mukumoto, Nobutaka M.S. [Department of Medical Physics and Engineering, Osaka University, Osaka (Japan); Mitsumori, Michihide [Department of Radiation Oncology and Image-Applied Therapy, Kyoto University, Kyoto (Japan); Teshima, Teruki [Department of Medical Physics and Engineering, Osaka University, Osaka (Japan)

2009-07-01

140

New results of laboratory experiments on the motion of rock avalanche: influence of the substratum, volume, slope angle and radius of curvature  

NASA Astrophysics Data System (ADS)

Rock avalanches are catastrophic events in which granular rock masses >106 m3 travel at velocities up to ten meters per second. The mobilized rock mass travel long distances, which in exceptional cases can reach up to tens of kilometers. Those highly destructive and uncontrollable events, give important insight to understand the interactions between the displaced masses and landscape conditions. However, as those events are not frequent, analogue modelling plays a fundamental role helping to the comprehension of their behaviour. The objective of the research is to explore the interaction among the rock mass and substratum conditions, slope angle and radius of curvature for long runout rock avalanches. For this work, an installation comprising three distinct parts was designed: a starting box where material is released (representing the detachment), a path along material spreads and the depositional surface. In order to have the best initial conditions, the starting box is quickly separated from the slope by means of a retractile jack which ensures a fast destabilisation of the mass. All the experiments are recorded with a high speed camera and in order to compare their shape and runout, the deposits are scanned with a mirco-Lidar Minolta. In a general way, the travel distance depends of the substratum. The Fahrböschung varies between 30° for the finer and 40° for the coarser but it can be considerably reduced by decreasing the basal friction. When aluminium is used as substratum, the Fahrböschung varies between 24° and 30°. The runout is greater with coarse material compare to finer one. The Fahrböschung got with finer grainsize is in average 3° higher than the one obtained with coarser grainsize. The travel increases with the volume.

Longchamp, Céline; Penna, Ivanna; Jaboyedoff, Michel

2013-04-01

141

The normalized magnetic helicity spectrum as a function of the angle between the local mean magnetic field and the flow direction of the solar wind: First results using high resolution magnetic field data from the Wind spacecraft  

NASA Astrophysics Data System (ADS)

This year, for the first time, the reduced normalized magnetic helicity spectrum has been analyzed as a function of the angle ? between the local mean magnetic field and the flow direction of the solar wind using wavelet techniques. In fast wind, at scales localized near k?p = 1 and kc/?pp = 1, where ?p is the thermal proton gyro-radius and c/?pp is the proton inertial length, the analysis reveals two distinct populations of fluctuations. There is a population of fluctuations at oblique angles, centered about an angle of 90 degrees, which are right hand polarized in the spacecraft frame and are believed to be associated with kinetic Alfven waves although the signal covers a wide range of oblique angles and a satisfactory interpretation of their spectrum through comparison with theory has not yet been obtained. A second population of fluctuations is found at angles near zero degrees which are left-hand polarized in the spacecraft frame. The data indicates that these are parallel propagating electromagnetic waves consisting either of left-hand polarized ion cyclotron waves propagating predominantly away from the sun or right-hand polarized whistler waves propagating predominantly toward the sun along the local mean magnetic field. As a consequence of the Doppler shift, both types of waves have the same polarization in the spacecraft frame. Unfortunately, the wave polarization in the plasma frame is difficult to determine using magnetic field data alone. Whether the observed waves are right- or left hand polarized in the plasma frame is a fundamental problem for future investigations. The analyses of spacecraft data performed so far have assumed that the solar wind velocity is directed radially outward from the sun. However, in the ecliptic plane at 1 AU, the flow direction typically deviates from the radial direction by a few degrees, sometimes more, and this adversely affects measurements of the angular helicity spectrum. To correct this, new measurements obtained using data from the Wind spacecraft use the scale dependent local mean solar wind velocity when computing the angle from the data. The first results from this study are presented here.

Podesta, J. J.

2011-12-01

142

Analysis of stratospheric NO2 trends above Jungfraujoch using ground-based UV-visible, FTIR, and satellite nadir observations  

NASA Astrophysics Data System (ADS)

The trend in stratospheric NO2 column at the NDACC (Network for the Detection of Atmospheric Composition Change) station of Jungfraujoch (46.5° N, 8.0° E) is assessed using ground-based FTIR and zenith-scattered visible sunlight SAOZ measurements over the period 1990 to 2009 as well as a composite satellite nadir data set constructed from ERS-2/GOME, ENVISAT/SCIAMACHY, and METOP-A/GOME-2 observations over the 1996-2009 period. To calculate the trends, a linear least squares regression model including explanatory variables for a linear trend, the mean annual cycle, the quasi-biennial oscillation (QBO), solar activity, and stratospheric aerosol loading is used. For the 1990-2009 period, statistically indistinguishable trends of -3.7 ± 1.1%/decade and -3.6 ± 0.9%/decade are derived for the SAOZ and FTIR NO2 column time series, respectively. SAOZ, FTIR, and satellite nadir data sets show a similar decrease over the 1996-2009 period, with trends of -2.4 ± 1.1%/decade, -4.3 ± 1.4%/decade, and -3.6 ± 2.2%/decade, respectively. The fact that these declines are opposite in sign to the globally observed +2.5%/decade trend in N2O, suggests that factors other than N2O are driving the evolution of stratospheric NO2 at northern mid-latitudes. Possible causes of the decrease in stratospheric NO2 columns have been investigated. The most likely cause is a change in the NO2/NO partitioning in favor of NO, due to a possible stratospheric cooling and a decrease in stratospheric chlorine content, the latter being further confirmed by the negative trend in the ClONO2 column derived from FTIR observations at Jungfraujoch. Decreasing ClO concentrations slows the NO + ClO ? NO2 + Cl reaction and a stratospheric cooling slows the NO + O3 ? NO2 + O2 reaction, leaving more NOx in the form of NO. The slightly positive trends in ozone estimated from ground- and satellite-based data sets are also consistent with the decrease of NO2 through the NO2 + O3 ? NO3 + O2 reaction. Finally, we cannot rule out the possibility that a strengthening of the Dobson-Brewer circulation, which reduces the time available for N2O photolysis in the stratosphere, could also contribute to the observed decline in stratospheric NO2 above Jungfraujoch.

Hendrick, F.; Mahieu, E.; Bodeker, G. E.; Boersma, K. F.; Chipperfield, M. P.; De Mazière, M.; De Smedt, I.; Demoulin, P.; Fayt, C.; Hermans, C.; Kreher, K.; Lejeune, B.; Pinardi, G.; Servais, C.; Stübi, R.; van der A, R.; Vernier, J.-P.; Van Roozendael, M.

2012-05-01

143

Analysis of stratospheric NO2 trends above Jungfraujoch using ground-based UV-visible, FTIR, and satellite nadir observations  

NASA Astrophysics Data System (ADS)

The trend in stratospheric NO2 column at the NDACC (Network for the Detection of Atmospheric Composition Change) station of Jungfraujoch (46.5° N, 8.0° E) is assessed using ground-based FTIR and zenith-scattered visible sunlight SAOZ measurements over the period 1990 to 2009 as well as a composite satellite nadir data set constructed from ERS-2/GOME, ENVISAT/SCIAMACHY, and METOP-A/GOME-2 observations over the 1996-2009 period. To calculate the trends, a linear least squares regression model including explanatory variables for a linear trend, the mean annual cycle, the quasi-biennial oscillation (QBO), solar activity, and stratospheric aerosol loading is used. For the 1990-2009 period, statistically indistinguishable trends of -3.7 ± 1.1% decade-1 and -3.6 ± 0.9% decade-1 are derived for the SAOZ and FTIR NO2 column time series, respectively. SAOZ, FTIR, and satellite nadir data sets show a similar decrease over the 1996-2009 period, with trends of -2.4 ± 1.1% decade-1, -4.3 ± 1.4% decade-1, and -3.6 ± 2.2% decade-1, respectively. The fact that these declines are opposite in sign to the globally observed +2.5% decade-1 trend in N2O, suggests that factors other than N2O are driving the evolution of stratospheric NO2 at northern mid-latitudes. Possible causes of the decrease in stratospheric NO2 columns have been investigated. The most likely cause is a change in the NO2/NO partitioning in favor of NO, due to a possible stratospheric cooling and a decrease in stratospheric chlorine content, the latter being further confirmed by the negative trend in the ClONO2 column derived from FTIR observations at Jungfraujoch. Decreasing ClO concentrations slows the NO + ClO ? NO2 + Cl reaction and a stratospheric cooling slows the NO + O3 ? NO2 + O2 reaction, leaving more NOx in the form of NO. The slightly positive trends in ozone estimated from ground- and satellite-based data sets are also consistent with the decrease of NO2 through the NO2 + O3 ? NO3 + O2 reaction. Finally, we cannot rule out the possibility that a strengthening of the Dobson-Brewer circulation, which reduces the time available for N2O photolysis in the stratosphere, could also contribute to the observed decline in stratospheric NO2 above Jungfraujoch.

Hendrick, F.; Mahieu, E.; Bodeker, G. E.; Boersma, K. F.; Chipperfield, M. P.; De Mazière, M.; De Smedt, I.; Demoulin, P.; Fayt, C.; Hermans, C.; Kreher, K.; Lejeune, B.; Pinardi, G.; Servais, C.; Stübi, R.; van der A, R.; Vernier, J.-P.; Van Roozendael, M.

2012-09-01

144

Extreme-Risk Prostate Adenocarcinoma Presenting With Prostate-Specific Antigen (PSA) >40 ng/ml: Prognostic Significance of the Preradiation PSA Nadir  

SciTech Connect

Purpose: To examine the impact of patient, disease, and treatment characteristics on survival outcomes in patients treated with neoadjuvant androgen deprivation therapy (ADT) and radical external-beam radiotherapy (RT) for clinically localized, extreme-risk prostate adenocarcinoma with a presenting prostate-specific antigen (PSA) concentration of >40 ng/ml. Methods and Materials: A retrospective chart review was conducted of 64 patients treated at a single institution between 1991 and 2000 with ADT and RT for prostate cancer with a presenting PSA level of >40 ng/ml. The effects of patient age, tumor (presenting PSA level, Gleason score, and T stage), and treatment (total ADT duration and pre-RT PSA level) characteristics on rates of biochemical disease-free survival (bDFS), prostate cancer-specific survival (PCSS), and overall survival (OS) were examined. Results: Median follow-up time was 6.45 years (range, 0.09-15.19 years). Actuarial bDFS, PCSS, and OS rates at 5 years were 39%, 87%, and 78%, respectively, and 17%, 64%, and 45%, respectively, at 10 years. On multivariate analysis, the pre-RT PSA level ({<=}0.1 versus >0.1 ng/ml) was the single most significant prognostic factor for bDFS (p = 0.033) and OS (p = 0.018) rates, whereas age, T stage, Gleason score, and ADT duration ({<=}6 versus >6 months) were not predictive of outcomes. Conclusion: In prostate cancer patients with high presenting PSA levels, >40 ng/ml, treated with combined modality, neoadjuvant ADT, and RT, the pre-RT PSA nadir, rather than ADT duration, was significantly associated with improved survival. This observation supports the use of neoadjuvant ADT to drive PSA levels to below 0.1 ng/ml before initiation of RT, to optimize outcomes for patients with extreme-risk disease.

Alexander, Abraham S. [British Columbia Cancer Agency, Vancouver Island Centre, Radiation Therapy Program, Victoria, British Columbia (Canada); University of British Columbia, Vancouver, British Columbia (Canada); Mydin, Aminudin; Jones, Stuart O.; Christie, Jennifer [British Columbia Cancer Agency, Vancouver Island Centre, Radiation Therapy Program, Victoria, British Columbia (Canada); Lim, Jan T.W. [British Columbia Cancer Agency, Vancouver Island Centre, Radiation Therapy Program, Victoria, British Columbia (Canada); University of British Columbia, Vancouver, British Columbia (Canada); Truong, Pauline T., E-mail: ptruong@bccancer.bc.ca [British Columbia Cancer Agency, Vancouver Island Centre, Radiation Therapy Program, Victoria, British Columbia (Canada); University of British Columbia, Vancouver, British Columbia (Canada); Ludgate, Charles M. [British Columbia Cancer Agency, Vancouver Island Centre, Radiation Therapy Program, Victoria, British Columbia (Canada); University of British Columbia, Vancouver, British Columbia (Canada)

2011-12-01

145

Influences of twilight on diurnal variation of core temperature, its nadir, and urinary 6-hydroxymelatonin sulfate during nocturnal sleep and morning drowsiness.  

PubMed

This study aimed at elucidating the physiological significance of dusk and dawn in the circadian rhythm of core temperature (T(core)) and urinary 6-hydroxymelatonin sulfate in humans during sleep and the waking sensation just after rising. Seven female and four male students served as participants. Participants retired at 2300 h and rose at 0700 h. They were requested to sit on a chair and spend time as quietly as possible during wakefulness, reading a book or listening to recorded light music. Two lighting conditions were provided for each participant: 1) Light-Dark (LD)-rectangular light change with abrupt decrease from 3,000 lx to 100 lx at 1800 h, abrupt increase from 0 lx to 3,000 lx at 0700 h. 2) LD-twilight light change with gradual decrease from 3,000 lx to 100 lx starting at 1700 h (twilight period about 2 h), with gradual increase from 0 lx to 3,000 lx starting at 0500 h (twilight period about 2 h). The periods of 0 lx at night were from 2300 h to 0700 h on the first day and from 2300 to 0500 h on the second day. Nadir time advanced significantly under the influence of the LD-twilight condition. The amount of 6-hydroxymelatonin sulfate in urine collected at 0200 h was significantly higher under LD-twilight in comparison with LD-rectangular light. Morning drowsiness tended to be lower under LD-twilight. Our results suggest that in architectural design of indoor illumination it is important to provide LD-twilight in the evening and early morning for sleep promotion in healthy normal people and/or light treatment in elderly patients with advanced dementia. PMID:19408625

Kondo, Masayuki; Tokura, Hiromi; Wakamura, Tomoko; Hyun, Ki-Ja; Tamotsu, Satoshi; Morita, Takeshi; Oishi, Tadashi

2009-03-01

146

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

147

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

148

Polygon Angle Applet  

NSDL National Science Digital Library

This interactive Java applet supports the investigation of the relationship between the number of vertices of a polygon and its interior angle sum. Learners choose and locate the vertices, the angle measures are displayed, and then the student can drag the measures into a circle to see them summed relative to 360 degrees.

Nicholas Exner

2000-05-31

149

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.

Barbara Henry

2012-04-16

150

Multi-angle Images of Hudson Bay and James Bay, Canada, 24 February 2000  

NASA Technical Reports Server (NTRS)

At left is a true-color image from the downward-looking (nadir)camera on the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite. The false-color image at right is a composite of red band data taken by the MISR forward 45.6-degree, nadir, and aftward 45.6-degree cameras, displayed in blue, green, and red colors, respectively. Color variations in the left image highlight spectral (true-color) differences, whereas those in the right image highlight differences in angular reflectance properties. The purple areas in the right image are low cloud, and light blue at the edge of the bay is due to increased forward scattering by the fast (smooth)ice. The orange areas are rougher ice, which scatters more light in the backward direction. This example illustrates how multi-angle viewing can distinguish physical structures and textures. Data for all channels are presented in a Space Oblique Mercator map projection to facilitate their co-registration. The images are about 400 km (250 miles) wide with a spatial resolution of about 275 meters (300 yards). North is toward the top. 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. JPL is a division of the California Institute of Technology.

2000-01-01

151

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

2010-10-01

152

Dynamic contact angle measurements on superhydrophobic surfaces  

NASA Astrophysics Data System (ADS)

In this paper, the dynamic advancing and receding contact angles of a series of aqueous solutions were measured on a number of hydrophobic and superhydrophobic surfaces using a modified Wilhelmy plate technique. Superhydrophobic surfaces are hydrophobic surfaces with micron or nanometer sized surface roughness. These surfaces have very large static advancing contact angles and little static contact angle hysteresis. In this study, the dynamic advancing and dynamic receding contact angles on superhydrophobic surfaces were measured as a function of plate velocity and capillary number. The dynamic contact angles measured on a smooth hydrophobic Teflon surface were found to obey the scaling with capillary number predicted by the Cox-Voinov-Tanner law, ?D3 ? Ca. The response of the dynamic contact angle on the superhydrophobic surfaces, however, did not follow the same scaling law. The advancing contact angle was found to remain constant at ?A = 160?, independent of capillary number. The dynamic receding contact angle measurements on superhydrophobic surfaces were found to decrease with increasing capillary number; however, the presence of slip on the superhydrophobic surface was found to result in a shift in the onset of dynamic contact angle variation to larger capillary numbers. In addition, a much weaker dependence of the dynamic contact angle on capillary number was observed for some of the superhydrophobic surfaces tested.

Kim, Jeong-Hyun; Kavehpour, H. Pirouz; Rothstein, Jonathan P.

2015-03-01

153

Later endogenous circadian temperature nadir relative to an earlier wake time in older people  

NASA Technical Reports Server (NTRS)

The contribution of the circadian timing system to the age-related advance of sleep-wake timing was investigated in two experiments. In a constant routine protocol, we found that the average wake time and endogenous circadian phase of 44 older subjects were earlier than that of 101 young men. However, the earlier circadian phase of the older subjects actually occurred later relative to their habitual wake time than it did in young men. These results indicate that an age-related advance of circadian phase cannot fully account for the high prevalence of early morning awakening in healthy older people. In a second study, 13 older subjects and 10 young men were scheduled to a 28-h day, such that they were scheduled to sleep at many circadian phases. Self-reported awakening from scheduled sleep episodes and cognitive throughput during the second half of the wake episode varied markedly as a function of circadian phase in both groups. The rising phase of both rhythms was advanced in the older subjects, suggesting an age-related change in the circadian regulation of sleep-wake propensity. We hypothesize that under entrained conditions, these age-related changes in the relationship between circadian phase and wake time are likely associated with self-selected light exposure at an earlier circadian phase. This earlier exposure to light could account for the earlier clock hour to which the endogenous circadian pacemaker is entrained in older people and thereby further increase their propensity to awaken at an even earlier time.

Duffy, J. F.; Dijk, D. J.; Klerman, E. B.; Czeisler, C. A.

1998-01-01

154

Wetting and Contact Angle  

NSDL National Science Digital Library

Students are presented with the concepts of wetting and contact angle. They are also introduced to the distinction between hydrophobic and hydrophilic surfaces. Students observe how different surfaces are used to maintain visibility under different conditions.

NSF CAREER Award and RET Program, Mechanical Engineering and Material Science,

155

Signature extension for sun angle, volume 1  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Within a restricted zenith sun angle range of 35 - 50 degrees, it was empirically observed that canopy reflectance is mainly Lambertian. Reflectance changes with crop stage were simple shifts in scale in the sun angle range. It was noted that sun angle variations depend on canopy characteristics. Effects of the vegetative canopy were most pronounced at the larger solar zenith angles (20 %). The linear sun angle correction coefficients demonstrate a dependency on both crop stage (15-20 %) and crop type (10-20 %). The use of canopy reflectance modeling allowed for the generation of a simulated data set over an extremely broad envelope of sun angles.

Smith, J. A. (principal investigator); Berry, J. K.; Heimes, F.

1975-01-01

156

Simulation studies for the detection of changes in broadband albedo and shortwave nadir reflectance spectra under a climate change scenario  

NASA Astrophysics Data System (ADS)

Climate forcing by greenhouse gases and aerosols and climate feedbacks from snow, sea-ice, and clouds all significantly impact the future evolution of the climate system's shortwave energy budget. We examine prospects for tracking changes in these forcings and feedbacks using top-of-atmosphere measurements of shortwave reflected radiation. We quantify the extent to which spectral measurements may reduce the time required to detect changes in the climate the climate system with high statistical confidence relative to conventional broadband measurements. We have developed an Observing System Simulation Experiment (OSSE) based on the Community Climate System Model 3.0 for the NASA CLARREO mission and have analyzed forced and unforced simulations of the 21st Century from the Intergovernmental Panel on Climate Change assessments. We find that changes in the simulated nadir spectral reflectance measurements in the visible window and between near-infrared water-vapor overtone channels under clear-sky conditions are detectible faster than the corresponding changes in broadband albedo, with many trends detectible within a five-year satellite mission lifetime. Under all-sky conditions, the superposition of unforced cloud variability on the secular climate trends lengthens the times required for climate-change detection in both the spectral and broadband data. However, migration of the ITCZ and stratus regions can be detected after 16-18 years of observation while broadband albedo measurements require 33-61 years of observation. We find that measurement uncertainty and instrument drift significantly lengthen detection times for broadband albedo and spectral reflectances in window channels but do not have the same effect for spectral measurements in water vapor bands.

Feldman, Daniel R.; Algieri, Chris A.; Collins, William D.; Roberts, Yolanda L.; Pilewskie, Peter A.

2011-12-01

157

The measurement of boundary layers on a compressor blade in cascade at high positive incidence angle. 1: Experimental techniques and results  

NASA Technical Reports Server (NTRS)

Measurements of the mean velocity and turbulence intensity were made using a one-component laser Doppler velocimeter in the boundary layer and near wake about a double circular arc, compressor blade in cascade. The measurements were made at a chord Reynolds number of 500,000. Boundary layer measurements on the pressure surface indicate a transition region over the last 40% of the chord. A small separation bubble near the leading edge of the suction surface results in an immediate transition from laminar to turbulent flow. The non-equilibrium turbulent boundary layer separates near the trailing edge of the suction surface. Similarity of the outer region of the turbulent boundary layer ceases to exist in the separated region. Also, similarity does not hold in the near-wake region, a region which includes negative mean velocities because of the separation near the trailing edge on the suction surface.

Deutsch, S.; Zierke, W. C.

1986-01-01

158

Data Plots of Run I - III Results from SLAC E-158: A precision Measurement of the Weak Mixing Angle in Moller Scattering  

DOE Data Explorer

Three physics runs were made in 2002 and 2003 by E-158. As a result, the E-158 Collaboration announced that it had made "the first observation of Parity Violation in electron-electron (Moller) scattering). This precise Parity Violation measurement gives the best determination of the electron's weak charge at low energy (low momentum transfer between interacting particles). E158's measurement tests the predicted running (or evolution) of this weak charge with energy, and searches for new phenomena at TeV energy scales (one thousand times the proton-mass energy scale).[Copied from the experiment's public home page at http://www-project slac.stanford.edu/3158/Default.htm] See also the E158 page for collaborators at http://www.slac.stanford.edu/exp/e158/. Both websites provide data and detailed information.

159

'Magic Angle Precession'  

SciTech Connect

An advanced and exact geometric description of nonlinear precession dynamics modeling very accurately natural and artificial couplings showing Lorentz symmetry is derived. In the linear description it is usually ignored that the geometric phase of relativistic motion couples back to the orbital motion providing for a non-linear recursive precession dynamics. The high coupling strength in the nonlinear case is found to be a gravitomagnetic charge proportional to the precession angle and angular velocity generated by geometric phases, which are induced by high-speed relativistic rotations and are relevant to propulsion technologies but also to basic interactions. In the quantum range some magic precession angles indicating strong coupling in a phase-locked chaotic system are identified, emerging from a discrete time dynamical system known as the cosine map showing bifurcations at special precession angles relevant to heavy nuclei stability. The 'Magic Angle Precession' (MAP) dynamics can be simulated and visualized by cones rolling in or on each other, where the apex and precession angles are indexed by spin, charge or precession quantum numbers, and corresponding magic angles. The most extreme relativistic warping and twisting effect is given by the Dirac spinor half spin constellation with 'Hyperdiamond' MAP, which resembles quark confinement.

Binder, Bernd [Quanics.com, Germany, 88679 Salem, P.O. Box 1247 (United States)], E-mail: binder@quanics.com

2008-01-21

160

Detecting blind building façades from highly overlapping wide angle aerial imagery  

NASA Astrophysics Data System (ADS)

This paper deals with the identification of blind building façades, i.e. façades which have no openings, in wide angle aerial images with a decimeter pixel size, acquired by nadir looking cameras. This blindness characterization is in general crucial for real estate estimation and has, at least in France, a particular importance on the evaluation of legal permission of constructing on a parcel due to local urban planning schemes. We assume that we have at our disposal an aerial survey with a relatively high stereo overlap along-track and across-track and a 3D city model of LoD 1, that can have been generated with the input images. The 3D model is textured with the aerial imagery by taking into account the 3D occlusions and by selecting for each façade the best available resolution texture seeing the whole façade. We then parse all 3D façades textures by looking for evidence of openings (windows or doors). This evidence is characterized by a comprehensive set of basic radiometric and geometrical features. The blindness prognostic is then elaborated through an (SVM) supervised classification. Despite the relatively low resolution of the images, we reach a classification accuracy of around 85% on decimeter resolution imagery with 60×40% stereo overlap. On the one hand, we show that the results are very sensitive to the texturing resampling process and to vegetation presence on façade textures. On the other hand, the most relevant features for our classification framework are related to texture uniformity and horizontal aspect and to the maximal contrast of the opening detections. We conclude that standard aerial imagery used to build 3D city models can also be exploited to some extent and at no additional cost for facade blindness characterisation.

Burochin, Jean-Pascal; Vallet, Bruno; Brédif, Mathieu; Mallet, Clément; Brosset, Thomas; Paparoditis, Nicolas

2014-10-01

161

Quantum Critical Transport and the Hall Angle  

E-print Network

In this letter we study the Hall conductivity in holographic models where translational invariance is broken by a lattice. We show that generic holographic theories will display a different temperature dependence in the Hall angle as to the DC conductivity. Our results suggest a general mechanism for obtaining an anomalous scaling of the Hall angle in strongly interacting quantum critical systems.

Mike Blake; Aristomenis Donos

2015-03-02

162

Tree Branch Angle: Maximizing Effective Leaf Area  

Microsoft Academic Search

In a computer simulation of branching pattern and leaf cluster in Terminalia catappa, right and left branch angles were varied, and the effective leaf surface areas were calculated. Theoretical branch angles that result in maximum effective leaf area are close to the values observed in nature.

Hisao Honda; Jack B. Fisher

1978-01-01

163

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

164

Meridional distribution of CH3C2H and C4H2 in Saturn’s stratosphere from CIRS/Cassini limb and nadir observations  

NASA Astrophysics Data System (ADS)

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 (C 4H 2) and methylacetylene (CH 3C 2H) mixing ratios in Saturn's stratosphere, from 5 hPa up to 0.05 hPa and 80°S to 45°N. We find that the C 4H 2 and CH 3C 2H meridional distributions mimic that of acetylene (C 2H 2), 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°S, at 0.1 and 0.05 hPa, we find that the CH 3C 2H and C 4H 2 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 CH 3C 2H and C 4H 2 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 -10 for C 4H 2 and of (1.1 ± 0.3) × 10 -9 for CH 3C 2H are compatible with the analysis of global-average ISO observations performed by Moses et al. (Moses, J.I., Bézard, B., Lellouch, E., Gladstone, G.R., Feuchtgruber, H., Allen, M. [2000a]. Icarus 143, 244-298). Finally, we provide values for the ratios [CH 3C 2H]/[C 2H 2] and [C 4H 2]/[C 2H 2] that can constrain the coupled chemistry of these hydrocarbons.

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

2010-10-01

165

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, ...

Mrs. Neubert

2011-03-10

166

Isoplanatic angle in finite distance: experimental validation  

NASA Astrophysics Data System (ADS)

Through theoretical analysis, we have previously proposed a method to measure an isoplanatic angle over a finite distance using three receiver apertures and a synthetic point source. Here, we present the validation experiment for this method. Through careful experimental design, the atmospheric coherence length for spherical waves propagating in the opposite direction was measured and converted to an isoplanatic angle as the true value for comparison. In general, the direct measurement of an isoplanatic angle agrees well with the true value in clear-air periods. Experimental results confirm our method for measuring an isoplanatic angle over a finite distance. The experiment resulted in the first time-diagram of an isoplanatic angle in finite distance ever measured through spherical-wave scintillation.

Yu, Long-Kun; Hou, Zai-Hong; Zhang, Shou-Chuan; Jing, Xu; Wu, Yi

2015-02-01

167

Utilizing the US Lab Nadir Research Window for Remote Sensing Operations with The Window Observational Research Facility (WORF)  

NASA Technical Reports Server (NTRS)

The Window Observational Research Facility (WORF) is an ISPR-based rack facility designed to take advantage of the high optical quality US Lab Nadir research window. The WORF is based on the ISS Expedite the Processing of Experiments to Space Station (EXPRESS) rack mechanical structure and electronic systems. The WORF has a unique payload volume located at the center of the rack that provides access to the window. The interior dimensions of the payload volume are 34-in. (86.36 cm) wide by 33-in. (83.82 cm) high by 23-in. (58.42 cm) deep. This facility supports the deployment of payloads such as 9 in. aerial photography cameras and 12 in. diameter optical equipment. The WORF coupled with the optical quality of the United States Lab window support the deployment of various payload disciplines. The WORF provides payloads with power, data command and control, air cooling, water cooling, and video processing. The WORF's payload mounting surfaces and interfaces include the interior payload mounting shelf and the interior and exterior aircraft-like seat tracks. The payload mounting shelf is limited to a maximum mass of 136 kg (299 pounds). The WORF can accommodate large payloads such as the commonly used Leica-Heerbrug RC-30 aerial photography camera (whose dimensions are 53.3 cm (21-in.) wide by 50.8 cm (20-in.) deep by 76.2 cm (30-in.) long). The performance characteristics of the WORF allow it to support an array of payload disciplines. The WORF provides a maximum of 3 Kw at 28 Vdc and has a maximum data rate of 10 Mbps. The WORF's unique payload volume is designed to be light-tight, down to 2.8 x 10(exp -11) Watts/cm2/steradian, and have low-reflective surfaces. This specially designed WORF interior supports payload investigations that observe low-light-level phenomenon such as aurora. Although the WORF rack does not employ any active rack isolation (i.e., vibration dampening) technology, the rack provides a very stable environment for payload operations (on the order of X microradians). The facility's software is capable of being updated during its period of deployment. The WORF project also includes a Suitcase Simulator to allow for a payload developer to verify data interfaces at his development site, a trainer rack for astronauts to learn how to operate the WORF prior to flight, and the use of the EXPRESS Functional Checkout Units to allow for payload checkout at the KSC prior to launch.

Turner, Richard; Barley, Bryan; Gilbert, Paul A. (Technical Monitor)

2002-01-01

168

Divergent-ray projection method for measuring the flapping angle, lag angle, and torsional angle of a bumblebee wing  

NASA Astrophysics Data System (ADS)

A divergent-ray projection (DRP) method was developed for measuring the flapping angle, lag angle, and torsional angle of bumblebee wing during beating motion. This new method can measure the spatial coordinates of an insect wing by digitizing the images that are projected by two divergent laser rays from different directions. The advantage of the DRP method is its ability to measure those three angles simultaneously using only one high-speed camera. The resolution of the DRP method can be changed easily by adjusting system parameters to meet the needs of different types of objects. The measurement results for these angles of a bumblebee wing probe the effectiveness of the DRP method in studying the flight performance of insects.

Zeng, Lijiang; Matsumoto, Hirokazu; Kawachi, Keiji

1996-11-01

169

Fixed-combination brinzolamide 1%/brimonidine 0.2% vs monotherapy with brinzolamide or brimonidine in patients with open-angle glaucoma or ocular hypertension: results of a pooled analysis of two phase 3 studies  

PubMed Central

Purpose To describe pooled efficacy and safety data from two phase 3 studies comparing brinzolamide 1%/brimonidine 0.2% fixed combination (BBFC) with its component medications, brinzolamide and brimonidine, in patients with open-angle glaucoma or ocular hypertension. Methods Data were pooled from two nearly identical clinical trials comparing BBFC with its component medications, each given three times daily. The 3-month efficacy outcome was mean intraocular pressure (IOP) at 0800, 1000, 1500, and 1700 hours. Safety outcomes included adverse events (AEs), best-corrected visual acuity, examination of ocular structures, pachymetry, perimetry, and vital signs. Results A total of 1350 patients were enrolled and included in this analysis (BBFC, n=437; brinzolamide, n=458; brimonidine, n=455). Baseline mean IOP levels were similar among the three treatment groups. At 3 months, mean IOP of the BBFC group was significantly lower than that of either monotherapy group (P<0.0001) at all the four time points. A total of 272 patients (20.1%) experienced at least one treatment-related AE (BBFC, 24.6% brinzolamide, 18.7% brimonidine, 17.4%), the majority of which were ocular AEs. One serious AE, moderate intensity chest pain, was considered related to brinzolamide treatment and resulted in study discontinuation. Conclusions This analysis strengthens the conclusions drawn from the two individual phase 3 studies showing that, in patients with open-angle glaucoma or ocular hypertension, BBFC had significantly superior IOP-lowering activity compared with either brinzolamide or brimonidine alone and a safety profile consistent with that of its individual components. PMID:23640612

Realini, T; Nguyen, Q H; Katz, G; DuBiner, H

2013-01-01

170

Contact angle hysteresis on fluoropolymer surfaces.  

PubMed

Contact angle hysteresis of liquids with different molecular and geometrical properties on high quality films of four fluoropolymers was studied. A number of different causes are identified for hysteresis. With n-alkanes as probe liquids, contact angle hysteresis is found to be strongly related to the configuration of polymer chains. The largest hysteresis is obtained with amorphous polymers whereas the smallest hysteresis occurs for polymers with ordered molecular chains. This is explained in terms of sorption of liquid by the solid and penetration of liquid into the polymer film. Correlation of contact angle hysteresis with the size of n-alkane molecules supports this conclusion. On the films of two amorphous fluoropolymers with different molecular configurations, contact angle hysteresis of one and the same liquid with "bulky" molecules is shown to be quite different. On the surfaces of Teflon AF 1600, with stiff molecular chains, the receding angles of the probe liquids are independent of contact time between solid and liquid and similar hysteresis is obtained for all the liquids. Retention of liquid molecules on the solid surface is proposed as the most likely cause of hysteresis in these systems. On the other hand, with EGC-1700 films that consist of flexible chains, the receding angles are strongly time-dependent and the hysteresis is large. Contact angle hysteresis increases even further when liquids with strong dipolar intermolecular forces are used. In this case, major reorganization of EGC-1700 chains due to contact with the test liquids is suggested as the cause. The effect of rate of motion of the three-phase line on the advancing and receding contact angles, and therefore contact angle hysteresis, is investigated. For low viscous liquids, contact angles are independent of the drop front velocity up to approximately 10 mm/min. This agrees with the results of an earlier study that showed that the rate-dependence of the contact angles is an issue only for liquids with high viscosity. PMID:17537391

Tavana, H; Jehnichen, D; Grundke, K; Hair, M L; Neumann, A W

2007-10-31

171

Exact ligand cone angles.  

PubMed

Many properties of transition-metal complexes depend on the steric bulk of bound ligands, usually quantified by the Tolman (?) and solid (?) cone angles, which have proven utility but suffer from various limitations and coarse approximations. Here, we present an improved, mathematically rigorous method to determine an exact cone angle (?°) by solving for the most acute right circular cone that contains the entire ligand. The procedure is applicable to any ligand, planar or nonplanar, monodentate or polydentate, bound to any metal center in any environment, and it is ideal for analyzing structures from quantum chemical computations as well as X-ray crystallography experiments. Exact cone angles were evaluated for a wide array of phosphine and amine ligands bound to palladium, nickel, or platinum by optimizing structures using B3LYP/6-31G* density functional theory with effective core potentials for the transition metals. The mean absolute deviations of the standard ? and ? parameters from the exact cone angles were 15-25°, mostly caused by distortions from the assumed idealized structures. PMID:23408559

Bilbrey, Jenna A; Kazez, Arianna H; Locklin, Jason; Allen, Wesley D

2013-05-30

172

Casting and Angling.  

ERIC Educational Resources Information Center

The self-contained packet contains background information, lesson plans, 15 transparency and student handout masters, drills and games, 2 objective examinations, and references for teaching a 15-day unit on casting and angling to junior high and senior high school students, either as part of a regular physical education program or as a club…

Little, Mildred J.; Bunting, Camille

173

Taxicab Angles and Trigonometry  

Microsoft Academic Search

A natural analogue to angles and trigonometry is developed in taxicab geometry. This structure is then analyzed to see which, if any, congruent triangle relations hold. A nice application involving the use of parallax to determine the exact (taxicab) distance to an object is also discussed.

Kevin Thompson; Tevian Dray

2011-01-01

174

open-angle glaucoma  

E-print Network

Purpose: To investigate whether associations with the nitric oxide synthase gene (NOS3) variants and risk of primary open-angle glaucoma (POAG) depend on female reproductive factors. Methods: Two functional and two tagging single nucleotide polymorphisms (SNPs; T-786C: rs2070744, Glu298Asp: rs

Jae Hee Kang; Janey L. Wiggs; Jonathan Haines; Wael Abdrabou; Louis R. Pasquale

175

Association Between Baseline Angle Width and Induced Angle Opening Following Prophylactic Laser Peripheral Iridotomy  

PubMed Central

Purpose. To evaluate the association between baseline angle width and laser peripheral iridotomy (LPI)-induced opening of the anterior chamber angle. Methods. Anterior segment optical coherence tomography images captured before and after LPI were analyzed to determine the angle opening distance at 250 ?m (AOD250), 500 ?m (AOD500), and 750 ?m (AOD750) from the scleral spur; trabecular–iris space area at 500 ?m (TISA500) and 750 ?m (TISA750) from the scleral spur; angle recess area at 750 ?m (ARA750) from the scleral spur; and trabecular–iris angle (TIA). Differences in preoperative and postoperative measurements for the anterior chamber angle width parameters were compared by paired Student's t-tests. Univariate and linear mixed-effects regression models were used to examine the association between baseline and LPI-induced opening of anterior chamber angle width parameters. Results. Eighty-four eyes of 52 primary angle closure suspects were included in the analysis. AOD250, AOD500, AOD750, TISA500, TISA750, ARA750, and TIA significantly increased following LPI by paired Student's t-tests (all P < 0.0001). Lower baseline measurements were significantly associated with greater postoperative opening in all anterior chamber angle width parameters in both univariate and linear mixed-effects regression analyses (all P < 0.05). Conclusions. Our results showed significant opening of the anterior chamber angle width after LPI and demonstrated an inverse association between baseline and LPI-induced opening of the anterior chamber angle width, such that eyes with a more crowded anterior chamber angle undergoing LPI had a greater magnitude of increase in anterior chamber angle width after the procedure. PMID:23661374

Lee, Roland Y.; Kasuga, Toshimitsu; Cui, Qi N.; Huang, Guofu; He, Mingguang; Lin, Shan C.

2013-01-01

176

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

177

Meridional distribution of CH 3C 2H and C 4H 2 in Saturn’s stratosphere from CIRS\\/Cassini limb and nadir observations  

Microsoft Academic Search

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 5hPa up to 0.05hPa and 80°S to 45°N. We find that the C4H2 and CH3C2H meridional distributions mimic that of acetylene (C2H2), exhibiting small-scale variations

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

2010-01-01

178

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

179

Find Angle Measures in Polygons  

NSDL National Science Digital Library

This lesson will introduce you to polygons and their angle measures. Focus on the Interior angles and exterior angles and their properties. First, let's discuss diagonals. What is a diagonal in a polygon? Play with and take notes on the following web site: Diagonals of a Polygon Now you are ready to learn the Polygon Interior Angles Theorem. It involves finding the measure of all of the angles inside a polygon, no matter how big or little ...

Mrs. Neubert

2011-02-09

180

Perceptions of tilt angles of an agricultural tractor.  

PubMed

A tractor stability simulator has been developed to help study tractor operators' perceptions of angles when the simulator is tilted to the side. The simulator is a trailer-mounted tractor cab equipped with hydraulic lift that can tilt the tractor cabin up to 30 degrees. This paper summarizes data from 82 participants who sat in the simulator while it was tilted. Demographic variables, estimates of tilt angles, and measured tilt angles were collected. The effects of age, gender, tractor driving experience, and frequency of operation on the estimated and measured tilt angles were analyzed. The results showed that about 50% of the participants reported estimations of side tilt angles within ±5 degrees of the actual angles, and nearly the same percentage overestimated the actual side tilt angles. Only a small percentage underestimated the angles. Older, more experienced, and male participants set higher limits on the actual angle at which they felt uncomfortable and would not drive. PMID:24417527

Görücü, Serap; Cavallo, Eugenio; Murphy, Dennis

2014-01-01

181

Angle amplifier based on multiplexed volume holographic gratings  

NASA Astrophysics Data System (ADS)

Angle amplifier of laser beam scanner is a widely used device in optical systems. Volume holographic optical elements can be applied in the angle amplifier. Compared with the traditional angle amplifier, it has the advantages of high angle resolution, high diffraction efficiency, small size, and high angle magnification and flexible design. Bragg anglewavelength- compensating recording method is introduced. Because of the Bragg compensatory relation between angle and wavelength, this device could be recorded at another wavelength. The design of the angle amplifier recording at the wavelength of 514.2nm for the working wavelength of 632.8nm is described. An optical setup for recording the angle amplifier device is designed and discussed. Experimental results in the photorefractive crystal Fe:LiNbO 3 demonstrate the feasibility of the angle amplifier scheme.

Cao, Liangcai; Zhao, Yifei; He, Qingsheng; Jin, Guofan

2008-03-01

182

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

183

Ducted turbine theory with right angled ducts  

NASA Astrophysics Data System (ADS)

This paper describes the use of an inviscid approach to model a ducted turbine - also known as a diffuser augmented turbine - and a comparison of results with a particular one-dimensional theory. The aim of the investigation was to gain a better understanding of the relationship between a real duct and the ideal diffuser, which is a concept that is developed in the theory. A range of right angled ducts, which have a rim for a 90° exit angle, were modelled. As a result, the performance of right angled ducts has been characterised in inviscid flow. It was concluded that right angled ducts cannot match the performance of their associated ideal diffuser and that the optimum rotor loading for these turbines varies with the duct dimensions.

McLaren-Gow, S.; Jamieson, P.; Graham, J. M. R.

2014-06-01

184

Radiometric stability of the Multi-angle Imaging SpectroRadiometer (MISR) following 15 years on-orbit  

NASA Astrophysics Data System (ADS)

The Multi-angle Imaging SpectroRadiometer (MISR) has successfully operated on the EOS/ Terra spacecraft since 1999. It consists of nine cameras pointing from nadir to 70.5° view angle with four spectral channels per camera. Specifications call for a radiometric uncertainty of 3% absolute and 1% relative to the other cameras. To accomplish this, MISR utilizes an on-board calibrator (OBC) to measure camera response changes. Once every two months the two Spectralon panels are deployed to direct solar-light into the cameras. Six photodiode sets measure the illumination level that are compared to MISR raw digital numbers, thus determining the radiometric gain coefficients used in Level 1 data processing. Although panel stability is not required, there has been little detectable change in panel reflectance, attributed to careful preflight handling techniques. The cameras themselves have degraded in radiometric response by 10% since launch, but calibration updates using the detector-based scheme has compensated for these drifts and allowed the radiance products to meet accuracy requirements. Validation using Sahara desert observations show that there has been a drift of ~1% in the reported nadir-view radiance over a decade, common to all spectral bands.

Bruegge, Carol J.; Val, Sebastian; Diner, David J.; Jovanovic, Veljko; Gray, Ellyn; Di Girolamo, Larry; Zhao, Guangyu

2014-09-01

185

Junction angles in drainage networks  

NASA Astrophysics Data System (ADS)

A theoretical model relating the junction angle of a tributary in a drainage network to its own Shreve magnitude and the Shreve magnitude of the stream into which it flows is developed and verified using published data (including Landsat maps) on U.S. networks with different underlying rock types, relief, and basin lengths. Good agreement is found, and a tendency for the slopes of individual network links to evolve toward graded longitudinal profiles as the network approaches an equilibrium (graded') planimetric pattern is noted. The differences between the network patterns predicted by the model and those observed on Mars are indicated, confirming the results of Pieri (1979, 1980).

Pieri, D. C.

1984-08-01

186

An angle representation of QCD  

E-print Network

For the sake of eliminating gauge variant degrees of freedom we discuss the way to introduce angular variables in the hamiltonian formulation of QCD. On the basis of an analysis of Gauss' law constraints a particular choice is made for the variable transformation from gauge fields to angular field variables. The resulting formulation is analogous to the one of Bars in terms of corner variables and it is closely related to the hamiltonian lattice QCD formulation. Therefore the corner or angle formulation may constitute an useful starting point for the investigation of the low energy properties of QCD in terms of gauge invariant degrees of freedom.

Dieter Stoll

1994-09-12

187

MRI 'magic angle' imaging of finger tendons.  

PubMed

The value of using the technique of magic angle MR imaging to demonstrate finger tendons is explored. Images of fresh frozen cadaveric specimens are presented and the structures that can be visualized in the finger are described. The results suggest that magic angle MR imaging may be a useful non-invasive technique of visualizing the details of the tendons and their surrounds in the hand. PMID:16182418

Lambe, G; Coutts, G; McArthur, P; Dangerfield, P H

2006-04-01

188

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

189

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

190

FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Temperature Influence on Divergence Angles of Quartz Crystal Wollaston Prism  

Microsoft Academic Search

We propose a structural angle and main refractive indices as two key factors to understand the temperature influence on the divergence angles of the Wollaston prism. The temperature influence on the divergence angles of quartz crystal Wollaston prism is studied theoretically The results show that divergence angles decrease with increasing temperature, while the divergence angle of e-light decrease more quickly

Shuang Zhao; Fu-Quan Wu; Dong-Sheng Zhang; Xin Zhao; Jin-Xi Wang; Mei Xue; Wei-Gang Zhong

2008-01-01

191

Creation of the ? angle standard for the flat angle measurements  

NASA Astrophysics Data System (ADS)

Angle measurements are based mainly on multiangle prisms - polygons with autocollimators, rotary encoders fo high accuracy and circular scales as the standards of the flat angle. Traceability of angle measurements is based on the standard of the plane angle - prism (polygon) calibrated at an appropriate accuracy. Some metrological institutions have established their special test benches (comparators) equipped with circular scales or rotary encoders of high accuracy and polygons with autocollimators for angle calibration purposes. Nevertheless, the standard (etalon) of plane angle - polygon has many restrictions for the transfer of angle unit - radian (rad) and other units of angle. It depends on the number of angles formed by the flat sides of the polygon that is restricted by technological and metrological difficulties related to the production and accuracy determination of the polygon. A possibility to create the standard of the angle equal to ? rad or half the circle or the full angle is proposed. It can be created by the circular scale with the rotation axis of very high accuracy and two precision reading instruments, usually, photoelectric microscopes (PM), placed on the opposite sides of the circular scale using the special alignment steps. A great variety of angle units and values can be measured and its traceability ensured by applying the third PM on the scale. Calibration of the circular scale itself and other scale or rotary encoder as well is possible using the proposed method with an implementation of ? rad as the primary standard angle. The method proposed enables to assure a traceability of angle measurements at every laboratory having appropriate environment and reading instruments of appropriate accuracy together with a rotary table with the rotation axis of high accuracy - rotation trajectory (runout) being in the range of 0.05 ?m. Short information about the multipurpose angle measurement test bench developed is presented.

Giniotis, V.; Rybokas, M.

2010-07-01

192

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

193

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

194

Skylab S-193 radar altimeter experiment analyses and results  

NASA Technical Reports Server (NTRS)

The design of optimum filtering procedures for geoid recovery is discussed. Statistical error bounds are obtained for pointing angle estimates using average waveform data. A correlation of tracking loop bandwidth with magnitude of pointing error is established. The impact of ocean currents and precipitation on the received power are shown to be measurable effects. For large sea state conditions, measurements of sigma 0 deg indicate a distinct saturation level of about 8 dB. Near-nadir less than 15 deg values of sigma 0 deg are also presented and compared with theoretical models. Examination of Great Salt Lake Desert scattering data leads to rejection of a previously hypothesized specularly reflecting surface. Pulse-to-pulse correlation results are in agreement with quasi-monochromatic optics theoretical predictions and indicate a means for estimating direction of pointing error. Pulse compression techniques for and results of estimating significant waveheight from waveform data are presented and are also shown to be in good agreement with surface truth data. A number of results pertaining to system performance are presented.

Brown, G. S. (editor)

1977-01-01

195

Investigation of drop dynamic contact angle on copper surface  

NASA Astrophysics Data System (ADS)

This paper presents experimental results of the studying the effect of surface roughness, microstructure and flow rate on the dynamic contact angle at spreading of distilled non deaerate water drop on a solid horizontal substrates. Copper substrates with different roughness have been investigated. For each substrate static contact angles depending on volume flow rate have been obtained using shadow system. Increasing the volume flow rate resulted in an increase of the static contact angle. It was found that with increasing surface roughness dynamic contact angle arises. Also difference in formation of the equilibrium contact angle at low and high rates of drop growth has been detected.

Orlova, Evgenija; Feoktistov, Dmitriy; Kuznetsov, Geniy

2015-01-01

196

The impact of inlet angle and outlet angle of guide vane on pump in reversal based hydraulic turbine performance  

NASA Astrophysics Data System (ADS)

In this paper, in order to research the impact of inlet angle and outlet angle of guide vane on hydraulic turbine performance, a centrifugal pump in reversal is adopted as turbine. A numerical simulation method is adopted for researching outer performance and flow field of turbine. The results show: inlet angle has a crucial role to turbine, to the same flow, there is a noticeable decline for the efficiency and head of turbine with the inlet angle increases. At the best efficiency point(EFP),to a same inlet angle, when the inlet angle greater than inlet angle, velocity circulation in guide vane outlet decreases, which lead the efficiency of turbine to reduce, Contrarily, the efficiency rises. With the increase of inlet angle and outlet angle, the EFP moves to the big flow area and the uniformity of pressure distribution becomes worse. The paper indicates that the inlet angle and outlet angle have great impact on the turbine performance, and the best combination exists for the inlet angle and outlet angle of the guide vane.

Shi, F. X.; Yang, J. H.; Wang, X. H.; Zhang, R. H.; Li, C. E.

2012-11-01

197

Evaluation of Terra and Aqua MODIS thermal emissive band response versus scan angle  

NASA Astrophysics Data System (ADS)

Terra and Aqua MODIS have operated near-continuously for over 14 and 12 years, respectively, and are key instruments for NASA's Earth Observing System. Observations from the 16 thermal emissive bands (TEB), covering wavelengths from 3.5 to 14.4 ?m with a nadir spatial resolution of 1 km are used to regularly generate a variety of atmosphere, ocean and land science products. The TEB detectors are calibrated using scan-by-scan observations of an on-board blackbody (BB). The current response versus scan angle (RVS) of the scan mirror was derived using a spacecraft deep-space pitch maneuver for Terra MODIS and characterized during prelaunch for Aqua MODIS. Earth view (EV) data over the complete range of angles of incidence (AOI) can be used to evaluate the on-orbit performance of the TEB RVS over the mission lifetime. Three approaches for tracking the TEB RVS on-orbit using EV observations are formulated. The first approach uses the multiple daily observations of Dome C BT at different AOI and their trend relative to coincident measurements from a ground temperature sensor. The second approach uses brightness temperatures (BT) retrieved over the cloud-free ocean to derive the trends at 13 AOI over the mission lifetime. The third approach tracks the dn response (normalized to the BB AOI) across the full swath width for Antarctic granules with the Dome C site at nadir. The viability of the three approaches is assessed and the long-term stability of the TEB RVS for both MODIS instruments is determined.

Wenny, B. N.; Wu, A.; Madhavan, S.; Xiong, X.

2014-10-01

198

Heterodyne Interferometer Angle Metrology  

NASA Technical Reports Server (NTRS)

A compact, high-resolution angle measurement instrument has been developed that is based on a heterodyne interferometer. The common-path heterodyne interferometer metrology is used to measure displacements of a reflective target surface. In the interferometer setup, an optical mask is used to sample the measurement laser beam reflecting back from a target surface. Angular rotations, around two orthogonal axes in a plane perpendicular to the measurement- beam propagation direction, are determined simultaneously from the relative displacement measurement of the target surface. The device is used in a tracking telescope system where pitch and yaw measurements of a flat mirror were simultaneously performed with a sensitivity of 0.1 nrad, per second, and a measuring range of 0.15 mrad at a working distance of an order of a meter. The nonlinearity of the device is also measured less than one percent over the measurement range.

Hahn, Inseob; Weilert, Mark A.; Wang, Xu; Goullioud, Renaud

2010-01-01

199

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

200

A New Angle on PV Efficiency  

NSDL National Science Digital Library

Students examine how the orientation of a photovoltaic (PV) panel relative to the sun affects the efficiency of the panel. Using sunshine (or a lamp) and a small PV panel connected to a digital multimeter, students vary the angle of the solar panel, record the resulting current output on a worksheet, and plot their experimental results.

Integrated Teaching and Learning Program,

201

8.G Find the Angle  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: In triangle $\\Delta ABC$, point $M$ is the point of intersection of the bisectors of angles $\\angle BAC$, $\\angle ABC$, and $\\angle ACB$. The measure o...

202

Solar cell angle of incidence corrections  

NASA Technical Reports Server (NTRS)

Literature on solar array angle of incidence corrections was found to be sparse and contained no tabular data for support. This lack along with recent data on 27 GaAs/Ge 4 cm by 4 cm cells initiated the analysis presented in this paper. The literature cites seven possible contributors to angle of incidence effects: cosine, optical front surface, edge, shadowing, UV degradation, particulate soiling, and background color. Only the first three are covered in this paper due to lack of sufficient data. The cosine correction is commonly used but is not sufficient when the incident angle is large. Fresnel reflection calculations require knowledge of the index of refraction of the coverglass front surface. The absolute index of refraction for the coverglass front surface was not known nor was it measured due to lack of funds. However, a value for the index of refraction was obtained by examining how the prediction errors varied with different assumed indices and selecting the best fit to the set of measured values. Corrections using front surface Fresnel reflection along with the cosine correction give very good predictive results when compared to measured data, except there is a definite trend away from predicted values at the larger incident angles. This trend could be related to edge effects and is illustrated by a use of a box plot of the errors and by plotting the deviation of the mean against incidence angle. The trend is for larger deviations at larger incidence angles and there may be a fourth order effect involved in the trend. A chi-squared test was used to determine if the measurement errors were normally distributed. At 10 degrees the chi-squared test failed, probably due to the very small numbers involved or a bias from the measurement procedure. All other angles showed a good fit to the normal distribution with increasing goodness-of-fit as the angles increased which reinforces the very small numbers hypothesis. The contributed data only went to 65 degrees from normal which prevented any firm conclusions about extreme angle effects although a trend in the right direction was seen. Measurement errors were estimated and found to be consistent with the conclusions that were drawn. A controlled experiment using coverglasses and cells from the same lots and extending to larger incidence angles would probably lead to further insight into the subject area.

Burger, Dale R.; Mueller, Robert L.

1995-01-01

203

Contact angle hysteresis: study by dynamic cycling contact angle measurements and variable angle spectroscopic ellipsometry on polyimide.  

PubMed

The phenomenon of contact angle hysteresis was studied on smooth films of polyimide, a polymer type used in the microelectronic industry, by dynamic cycling contact angle measurements based on axisymmetric drop shape analysis-profile in combination with variable angle spectroscopic ellipsometry (VASE). It was found that both advancing and receding contact angles became smaller with increasing the number of cycles and are, therefore, not a property of the dry solid alone. The changes of the wetting behavior during these dynamic cycling contact angle measurements are attributed mainly to swelling and/or liquid retention. To reveal the water-induced changes of the polymer film, the polyimide surface was studied before and after the contact with a water droplet by VASE. Both the experimental ellipsometric spectrum for Delta and that for Psi as well as the corresponding simulations show characteristic shifts due to the contact with water. The so-called effective medium approximation was applied to recover information about the thickness and effective optical constants of the polymer layer from the ellipsometrically measured values of Delta and Psi. On the basis of these results, the swelling and retention behavior of the polyimide films in contact with water droplets were discussed. PMID:15274573

Hennig, A; Eichhorn, K-J; Staudinger, U; Sahre, K; Rogalli, M; Stamm, M; Neumann, A W; Grundke, K

2004-08-01

204

CONTRIBUTIONS Large angle pair production  

E-print Network

does not decrease with energy ; 4) total cross-section for muon pair production in electron Institute (USSR) Abstract. - Total cross sections for e* + e- -t e' + e- + Wf + W- processes are obtained of a pair of particles on an electron at large angles ; 3) photon emission at a large angle when the cross-section

Paris-Sud XI, Université de

205

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

206

Goniometer-rotation-angle recorder  

SciTech Connect

This paper describes a goniometer-rotation-angle recorder with a discrete drive. The rotation angle in a given plane is recorded by bidirectional sign counter of positive and negative drive-actuation numbers for rotations in positive and negative directions. The maximum capacity of the counter is + or - 9 decimal digits.

Shchagin, A.V.

1985-12-01

207

Spinning angle optical calibration apparatus  

DOEpatents

An optical calibration apparatus is provided for calibrating and reproducing spinning angles in cross-polarization, nuclear magnetic resonance spectroscopy. An illuminated magnifying apparatus enables optical setting an accurate reproducing of spinning "magic angles" in cross-polarization, nuclear magnetic resonance spectroscopy experiments. A reference mark scribed on an edge of a spinning angle test sample holder is illuminated by a light source and viewed through a magnifying scope. When the "magic angle" of a sample material used as a standard is attained by varying the angular position of the sample holder, the coordinate position of the reference mark relative to a graduation or graduations on a reticle in the magnifying scope is noted. Thereafter, the spinning "magic angle" of a test material having similar nuclear properties to the standard is attained by returning the sample holder back to the originally noted coordinate position.

Beer, Stephen K. (Morgantown, WV); Pratt, II, Harold R. (Morgantown, WV)

1991-01-01

208

Changes in angle of optic nerve and angle of ocular orbit with increasing age in Japanese children  

PubMed Central

Purpose To study changes in the opening angle of the optic nerve and the angle of the ocular orbit with increasing age in normal Japanese children. Methods We studied 147 normal children (aged 6?months to 18?years) who had undergone CT as a diagnostic procedure. Measurements were performed on axial CT images that included the entire optic nerve of both eyes. The opening angle of the optic nerve was defined as the angle formed by the intersection of a line running through the left optic nerve and a vertical line passing through the centre of the nose. The opening angle of the orbit was defined as the angle formed by the intersection of a line running tangentially along the deep lateral wall of the left orbit and a vertical line passing through the centre of the nose. The relationship between age and these opening angles was analysed by regression analysis. Results The correlation between age and opening angle of the optic nerve was not significant. In contrast, the opening angle of the orbit decreased relatively rapidly until about 2–3?years of age, and then it stabilised. The decrease in the opening angle of the orbit with increasing age was significant (p<0.001). The relationship between these two parameters was best fitted by a logarithmic regression curve. Conclusions Because the opening angle of the orbit decreased significantly with increasing age, this factor must be considered when diagnosing and treating strabismus in children. PMID:25147368

Tsukitome, Hideyuki; Hatsukawa, Yoshikazu; Morimitsu, Tomoko; Yagasaki, Teiji; Kondo, Mineo

2015-01-01

209

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

210

Flow angle effects in E region 398-MHz auroral backscatter at small aspect angle  

NASA Astrophysics Data System (ADS)

A study of flow angle effects on small aspect angle backscatter from the auroral E region has been made using data obtained in the 1970s with the 398-MHz radar at Homer, Alaska. Several findings differ from previous results obtained at 140 MHz with the Scandinavian Twin Auroral Radar Experiment and the Sweden and Britain Radar-Auroral Experiment radars: (1) backscatter power is virtually independent of flow angle; (2) there is much less difference between type 1 and type 2 echoes; (3) as found in previous UHF studies, Doppler velocities of type 2 (low Doppler velocity) echoes vary with flow angle more rapidly than predicted by the ``cosine law.'' These differences are considered in the light of the recent strong turbulence theory developed by Hamza and St-Maurice [1993a,b].

Moorcroft, D. R.

1996-06-01

211

Particle friction angles in steep mountain channels  

NASA Astrophysics Data System (ADS)

Sediment transport rates in steep mountain channels are typically an order of magnitude lower than predicted by models developed for lowland rivers. One hypothesis for this observation is that particles are more stable in mountain channels due to particle-particle interlocking or bridging across the channel width. This hypothesis has yet to be tested, however, because we lack direct measurements of particle friction angles in steep mountain channels. Here we address this data gap by directly measuring the minimum force required to dislodge sediment (pebbles to boulders) and the sediment weight in mountain channels using a handheld force gauge. At eight sites in California, with reach-averaged bed angles ranging from 0.5° to 23° and channel widths ranging from 2 m to 16 m, we show that friction angles in natural streams average 68° and are 16° larger than those typically measured in laboratory experiments, which is likely due to particle interlocking and burial. Results also show that larger grains are disproportionately more stable than predicted by existing models and that grains organized into steps are twice as stable as grains outside of steps. However, the mean particle friction angle does not vary systematically with bed slope. These results do not support systematic increases in friction angle in steeper and narrower channels to explain the observed low sediment transport rates in mountain channels. Instead, the spatial pattern and grain-size dependence of particle friction angles may indirectly lower transport rates in steep, narrow channels by stabilizing large clasts and channel-spanning steps, which act as momentum sinks due to form drag.

Prancevic, Jeff P.; Lamb, Michael P.

2015-02-01

212

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

213

Prospective case series on trabecular-iris angle status after an acute episode of phacomorphic angle closure  

PubMed Central

AIM To investigate the trabecular-iris angle with ultrasound biomicroscopy (UBM) post cataract extraction after an acute attack of phacomorphic angle closure. METHODS This prospective study involved 10 cases of phacomorphic angle closure that underwent cataract extraction and intraocular lens insertion after intraocular pressure (IOP) lowering. Apart from visual acuity and IOP, the trabecular-iris angle was measured by gonioscopy and UBM at 3 months post attack. RESULTS In 10 consecutive cases of acute phacomorphic angle closure from December 2009 to December 2010, gonioscopic findings showed peripheral anterior synechiae (PAS) ? 90° in 30% of phacomorphic patients and a mean Shaffer grading of (3.1±1.0). UBM showed a mean angle of (37.1°±4.5°) in the phacomorphic eye with the temporal quadrant being the most opened and (37.1°±8.0°) in the contralateral uninvolved eye. The mean time from consultation to cataract extraction was (1.4±0.7) days and the mean total duration of phacomorphic angle closure was (3.6±2.8) days but there was no correlation to the degree of angle closure on UBM (Spearman correlation P=0.7). The presenting mean IOP was (50.5±7.4) mmHg and the mean IOP at 3 months was (10.5±3.4) mmHg but there were no correlations with the degree of angle closure (Spearman correlations P=0.9). CONCLUSION An open trabecular-iris angle and normal IOP can be achieved after an acute attack of phacomorphic angle closure if cataract extraction is performed within 1 day - 2 days after IOP control. Gonioscopic findings were in agreement with UBM, which provided a more specific and object angle measurement. The superior angle is relatively more narrowed compared to the other quadrants. All contralateral eyes in this series had open angles. PMID:23549291

Lee, Jacky; Lai, Jimmy; Yick, Doris; Yuen, Can

2013-01-01

214

Emission angle distribution and flavor transformation of supernova neutrinos  

E-print Network

Using moment equations we analyze collective flavor transformation of supernova neutrinos. We study the convergence of moment equations and find that numerical results using a few moment converge quite fast. We study effects of emission angle distribution of neutrinos on neutrino sphere. We study scaling law of the amplitude of neutrino self-interaction Hamiltonian and find that it depends on model of emission angle distribution of neutrinos. Dependence of neutrino oscillation on different models of emission angle distribution is studied.

Wei Liao

2009-06-28

215

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

216

Positron Emission Mammography with Multiple Angle Acquisition  

SciTech Connect

Positron emission mammography (PEM) of F-18 fluorodeoxyglucose (FDG) uptake in breast tumors with dedicated detectors typically has been accomplished with two planar detectors in a fixed position with the breast under compression. The potential use of PEM imaging at two detector positions to guide stereotactic breast biopsy has motivated us to use PEM coincidence data acquired at two or more detector positions together in a single image reconstruction. Multiple angle PEM acquisition and iterative image reconstruction were investigated using point source and compressed breast phantom acquisitions with 5, 9, 12 and 15 mm diameter spheres and a simulated tumor:background activity concentration ratio of 6:1. Image reconstruction was performed with an iterative MLEM algorithm that used coincidence events between any two detector pixels on opposed detector heads at each detector position. This present study compared two acquisition protocols: 2 angle acquisition with detector angular positions of -15 and +15 degrees and 11 angle acquisition with detector positions spaced at 3 degree increments over the range -15 to +15 degrees. Three- dimensional image resolution was assessed for the point source acquisitions, and contrast and signal-to-noise metrics were evaluated for the compressed breast phantom with different simulated tumor sizes. Radial and tangential resolutions were similar for the two protocols, while normal resolution was better for the 2 angle acquisition. Analysis is complicated by the asymmetric point spread functions. Signal- to-noise vs. contrast tradeoffs were better for 11 angle acquisition for the smallest visible 9 mm sphere, while tradeoff results were mixed for the larger and more easily visible 12 mm and 15 mm diameter spheres. Additional study is needed to better understand the performance of limited angle tomography for PEM. PEM tomography experiments with complete angular sampling are planned.

Mark F. Smith; Stan Majewski; Raymond R. Raylman

2002-11-01

217

Positron Emission Mammography with Multiple Angle Acquisition  

SciTech Connect

Positron emission mammography (PEM) of F-18 fluorodeoxyglucose (FbG) uptake in breast tumors with dedicated detectors typically has been accomplished with two planar detectors in a fixed position with the breast under compression. The potential use of PEM imaging at two detector positions to guide stereotactic breast biopsy has motivated us to use PEM coincidence data acquired at two or more detector positions together in a single image reconstruction. Multiple angle PEM acquisition and iterative image reconstruction were investigated using point source and compressed breast phantom acquisitions with 5, 9, 12 and 15 mm diameter spheres and a simulated tumor:background activity concentration ratio of 6:1. Image reconstruction was performed with an iterative MLEM algorithm that used coincidence events between any two detector pixels on opposed detector heads at each detector position. This present study compared two acquisition protocols: 2 angle acquisition with detector angular positions of -15 and +15 degrees and 11 angle acquisition with detector positions spaced at 3 degree increments over the range -15 to +15 degrees. Three-dimensional image resolution was assessed for the point source acquisitions, and contrast and signal-to-noise metrics were evaluated for the compressed breast phantom with different simulated tumor sizes. Radial and tangential resolutions were similar for the two protocols, while normal resolution was better for the 2 angle acquisition. Analysis is complicated by the asymmetric point spread functions. Signal- to-noise vs. contrast tradeoffs were better for 11 angle acquisition for the smallest visible 9 mm sphere, while tradeoff results were mixed for the larger and more easily visible 12 mm and 15 mm diameter spheres. Additional study is needed to better understand the performance of limited angle tomography for PEM. PEM tomography experiments with complete angular sampling are planned.

Mark F. Smith; Stan Majewski; Raymond R. Raylman

2002-11-01

218

Relativistic Transformation of Solid Angle.  

ERIC Educational Resources Information Center

Rederives the relativistic transformations of light intensity from compact sources (stars) to show where and how the transformation of a solid angle contributes. Discusses astrophysical and other applications of the transformations. (Author/CS)

McKinley, John M.

1980-01-01

219

Two Comments on Bond Angles  

NASA Astrophysics Data System (ADS)

Tetrahedral Bond Angle from Elementary Trigonometry The alternative approach of using the scalar (or dot) product of vectors enables the determination of the bond angle in a tetrahedral molecule in a simple way. There is, of course, an even more straightforward derivation suitable for students who are unfamiliar with vectors, or products thereof, but who do know some elementary trigonometry. The starting point is the figure showing triangle OAB. The point O is the center of a cube, and A and B are at opposite corners of a face of that cube in which fits a regular tetrahedron. The required bond angle alpha = AÔB; and using Pythagoras' theorem, AB = 2(square root 2) is the diagonal of a face of the cube. Hence from right-angled triangle OEB, tan(alpha/2) = (square root 2) and therefore alpha = 2tan-1(square root 2) is approx. 109° 28' (see Fig. 1).

Glaister, P.

1997-09-01

220

Solar Angles and Tracking Systems  

NSDL National Science Digital Library

Students learn about the daily and annual cycles of solar angles used in power calculations to maximize photovoltaic power generation. They gain an overview of solar tracking systems that improve PV panel efficiency by following the sun through the sky.

2014-09-18

221

Measurements of integral muon intensity at large zenith angles  

E-print Network

High-statistics data on near-horizontal muons collected with Russian-Italian coordinate detector DECOR are analyzed. Precise measurements of muon angular distributions in zenith angle interval from 60 to 90 degrees have been performed. In total, more than 20 million muons are selected. Dependences of the absolute integral muon intensity on zenith angle for several threshold energies ranging from 1.7 GeV to 7.2 GeV are derived. Results for this region of zenith angles and threshold energies have been obtained for the first time. The dependence of integral intensity on zenith angle and threshold energy is well fitted by a simple analytical formula.

Dmitrieva, A N; Kokoulin, R P; Kompaniets, K G; Mannocchi, G; Petrukhin, A A; Saavedra, O; Shutenko, V V; Timashkov, D A; Trinchero, G; Yashin, I I

2006-01-01

222

Measurements of integral muon intensity at large zenith angles  

E-print Network

High-statistics data on near-horizontal muons collected with Russian-Italian coordinate detector DECOR are analyzed. Precise measurements of muon angular distributions in zenith angle interval from 60 to 90 degrees have been performed. In total, more than 20 million muons are selected. Dependences of the absolute integral muon intensity on zenith angle for several threshold energies ranging from 1.7 GeV to 7.2 GeV are derived. Results for this region of zenith angles and threshold energies have been obtained for the first time. The dependence of integral intensity on zenith angle and threshold energy is well fitted by a simple analytical formula.

A. N. Dmitrieva; D. V. Chernov; R. P. Kokoulin; K. G. Kompaniets; G. Mannocchi; A. A. Petrukhin; O. Saavedra; V. V. Shutenko; D. A. Timashkov; G. Trinchero; I. I. Yashin

2006-11-28

223

Improved eddy current angle probe  

SciTech Connect

Apparatus is described for detecting flaws in a tubular workpiece in a single scan. The coils of a dual coil bobbin eddy current inspection probe are wound at a 45/sup 0/ angle to the transverse axis of the probe, one coil having an angular position about the axis about 90/sup 0/ relative to the angular position of the other coil, and the angle of intersection of the planes containing the coils being about 60/sup 0/.

Nance, R.A.; Hartley, W.H.; Caffarel, A.J.

1982-02-11

224

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

PubMed Central

Objective 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 to a low carbohydrate/high fat meal. Design 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. Results 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. Conclusions 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

2014-01-01

225

A robust polynomial fitting approach for contact angle measurements.  

PubMed

Polynomial fitting to drop profile offers an alternative to well-established drop shape techniques for contact angle measurements from sessile drops without a need for liquid physical properties. Here, we evaluate the accuracy of contact angles resulting from fitting polynomials of various orders to drop profiles in a Cartesian coordinate system, over a wide range of contact angles. We develop a differentiator mask to automatically find a range of required number of pixels from a drop profile over which a stable contact angle is obtained. The polynomial order that results in the longest stable regime and returns the lowest standard error and the highest correlation coefficient is selected to determine drop contact angles. We find that, unlike previous reports, a single polynomial order cannot be used to accurately estimate a wide range of contact angles and that a larger order polynomial is needed for drops with larger contact angles. Our method returns contact angles with an accuracy of <0.4° for solid-liquid systems with ? < ~60°. This compares well with the axisymmetric drop shape analysis-profile (ADSA-P) methodology results. Above about 60°, we observe significant deviations from ADSA-P results, most likely because a polynomial cannot trace the profile of drops with close-to-vertical and vertical segments. To overcome this limitation, we implement a new polynomial fitting scheme by transforming drop profiles into polar coordinate system. This eliminates the well-known problem with high curvature drops and enables estimating contact angles in a wide range with a fourth-order polynomial. We show that this approach returns dynamic contact angles with less than 0.7° error as compared to ADSA-P, for the solid-liquid systems tested. This new approach is a powerful alternative to drop shape techniques for estimating contact angles of drops regardless of drop symmetry and without a need for liquid properties. PMID:23570502

Atefi, Ehsan; Mann, J Adin; Tavana, Hossein

2013-05-14

226

Quantum critical transport and the Hall angle in holographic models.  

PubMed

We study the Hall conductivity in holographic models where translational invariance is broken by a lattice. We show that generic holographic theories will display a different temperature dependence in the Hall angle as to the dc conductivity. Our results suggest a general mechanism for obtaining an anomalous scaling of the Hall angle in strongly interacting quantum critical systems. PMID:25635540

Blake, Mike; Donos, Aristomenis

2015-01-16

227

Quantum Critical Transport and the Hall Angle in Holographic Models  

NASA Astrophysics Data System (ADS)

We study the Hall conductivity in holographic models where translational invariance is broken by a lattice. We show that generic holographic theories will display a different temperature dependence in the Hall angle as to the dc conductivity. Our results suggest a general mechanism for obtaining an anomalous scaling of the Hall angle in strongly interacting quantum critical systems.

Blake, Mike; Donos, Aristomenis

2015-01-01

228

Maximum angle of horizontal strabismus consistent with true stereopsis  

Microsoft Academic Search

BackgroundWe prospectively evaluated the performance of three stereoacuity tests in patients with a wide range of strabismus angles to determine the maximum angle of horizontal strabismus consistent with true stereopsis as well as the extent of false-positive results.

David A. Leske; Jonathan M. Holmes

2004-01-01

229

Peripapillary Schisis in Glaucoma Patients With Narrow Angles and  

E-print Network

Peripapillary Schisis in Glaucoma Patients With Narrow Angles and Increased Intraocular Pressure cases of peripapillary retinal schisis in patients with glaucoma without evidence of optic nerve pits patient was followed over time. RESULTS: The first patient, diagnosed with narrow angle glaucoma

Srinivasan, Vivek J.

230

A modern view of wide-angle exclusive scattering  

E-print Network

The basic theoretical ideas of the handbag mechanism for wide-angle exclusive scattering reactions are discussed and, with regard to the present experimental program carried out at JLab, its application to Compton scattering is reviewed in some detail. Results for other wide-angle reactions such as two-photon annihilations into pairs of hadrons or virtual Compton scattering are presented as well.

P. Kroll

2003-02-19

231

Evaluation of Protein Dihedral Angle Prediction Methods  

PubMed Central

Tertiary structure prediction of a protein from its amino acid sequence is one of the major challenges in the field of bioinformatics. Hierarchical approach is one of the persuasive techniques used for predicting protein tertiary structure, especially in the absence of homologous protein structures. In hierarchical approach, intermediate states are predicted like secondary structure, dihedral angles, C?-C? distance bounds, etc. These intermediate states are used to restraint the protein backbone and assist its correct folding. In the recent years, several methods have been developed for predicting dihedral angles of a protein, but it is difficult to conclude which method is better than others. In this study, we benchmarked the performance of dihedral prediction methods ANGLOR and SPINE X on various datasets, including independent datasets. TANGLE dihedral prediction method was not benchmarked (due to unavailability of its standalone) and was compared with SPINE X and ANGLOR on only ANGLOR dataset on which TANGLE has reported its results. It was observed that SPINE X performed better than ANGLOR and TANGLE, especially in case of prediction of dihedral angles of glycine and proline residues. The analysis suggested that angle shifting was the foremost reason of better performance of SPINE X. We further evaluated the performance of the methods on independent ccPDB30 dataset and observed that SPINE X performed better than ANGLOR. PMID:25166857

Raghava, Gajendra P. S.

2014-01-01

232

Enhanced sensitivity growth hormone (GH) chemiluminescence assay reveals lower postglucose nadir GH concentrations in men than women  

Microsoft Academic Search

ABSTRACT Modifications,were,made,to a commercially,available,human,(h) GH chemiluminescence assay (Nichols Luma Tag hGH assay), which im- proved,its sensitivity,to,0.002 fig\\/L. The,results,of,this,assay,had,a high,correlation,with,those,of,the,Nichols,hGH,immunoradiometric assay,(IRMA; r = 0.91; P < 0.001). The,addition,of recombinant,hGH- binding,protein,(0.1-10 nmol\\/L),to,standards,and,serum,samples caused,a dose-responsive,reduction,in measured,GH in both,the,chemi- luminescence,assay,and,the,IRMA; at physiological,concentrations,of hGH-binding protein, a lo-20% reduction was observed. Fifteen nor- mal,young,adults,(nine,men,and,six,women),underwent,a standard 100-g oral glucose tolerance test, and plasma GH was measured from

I. M. Chapman; M. L. Hartman; M. Straume; M. L. Johnson; J. D. Veldhuisups

1994-01-01

233

30 CFR 57.19037 - Fleet angles.  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 2011-07-01 false Fleet angles. 57.19037 Section 57.19037 Mineral Resources...Hoisting Headframes and Sheaves § 57.19037 Fleet angles. Fleet angles on hoists installed after November 15, 1979,...

2011-07-01

234

30 CFR 56.19037 - Fleet angles.  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 2011-07-01 false Fleet angles. 56.19037 Section 56.19037 Mineral Resources...Hoisting Headframes and Sheaves § 56.19037 Fleet angles. Fleet angles on hoists installed after November 15, 1979,...

2011-07-01

235

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

236

Weak lensing using only galaxy position angles  

NASA Astrophysics Data System (ADS)

We develop a method for performing a weak lensing analysis using only measurements of galaxy position angles. By analysing the statistical properties of the galaxy orientations given a known intrinsic ellipticity distribution, we show that it is possible to obtain estimates of the shear by minimizing a ?2 statistic. The method is demonstrated using simulations where the components of the intrinsic ellipticity are taken to be Gaussian distributed. Uncertainties in the position angle measurements introduce a bias into the shear estimates which can be reduced to negligible levels by introducing a correction term into the formalism. We generalize our approach by developing an algorithm to obtain direct shear estimators given any azimuthally symmetric intrinsic ellipticity distribution. We introduce a method of measuring the position angles of the galaxies from noisy pixelized images, and propose a method to correct for biases which arise due to pixelization and correlations between measurement errors and galaxy ellipticities. We also develop a method to constrain the sample of galaxies used to obtain an estimate of the intrinsic ellipticity distribution such that fractional biases in the resulting shear estimates are below a given threshold value. We demonstrate the angle-only method by applying it to simulations where the ellipticities are taken to follow a lognormal distribution. We compare the performance of the position-angle-only method with the standard method based on full ellipticity measurements by reconstructing lensing convergence maps from both numerical simulations and from the Canada-France-Hawaii Lensing Survey data. We find that the difference between the convergence maps reconstructed using the two methods is consistent with noise.

Whittaker, Lee; Brown, Michael L.; Battye, Richard A.

2014-12-01

237

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

238

LINTRAN v2.0: A linearised vector radiative transfer model for efficient simulation of satellite-born nadir-viewing reflection measurements of cloudy atmospheres  

NASA Astrophysics Data System (ADS)

Radiance measurements of solar radiation that is backscattered by the Earth?s atmosphere or surface contain information about the atmospheric composition and the state of the Earth?s surface. Retrieving such information from satellite-based observations in nadir geometry employs a radiative transfer forward model. The forward model simulates the observed quantity, aiming to reproduce the observation. LINTRAN v2.0 is a linearised vector radiative transfer forward model, employing forward-adjoint theory, that is capable of modelling cloud contaminated satellite observations and their derivatives with respect to the state of the atmosphere and the Earth?s surface in a numerically efficient manner. A significant gain in efficiency with respect to its predecessor (LINTRAN v1.0) is achieved through a mathematical framework that combines an approximate iterative solving method using the forward-adjoint perturbation theory with separation of the first N orders of scattering from the diffuse intensity vector field. Contributions to the observable up to order of scattering N are recursively solved in an analytical manner. Contributions from higher orders of scattering are subsequently solved in a numerical manner, assuming that the intensity field varies linearly with the vertical coordinate within an optically homogeneous model layer. This method is implemented in LINTRAN v2.0, choosing N=2, within the general framework of forward-adjoint perturbation theory. This new approach allows us to decrease the number of model layers and the degree of angular quadrature within the numerical solver by a factor of 10 and 1.4 respectively, compared to the previous model version, assuming a homogeneous atmosphere loaded with scattering Mie particles (size parameter ??35). In this homogeneous atmosphere, the reduced discretisation sampling in turn reduces the numerical effort associated with the numerical matrix solver by a factor of 42 relative to the previous model version, without a loss in model accuracy.

Schepers, D.; aan de Brugh, J. M. J.; Hahne, Ph.; Butz, A.; Hasekamp, O. P.; Landgraf, J.

2014-12-01

239

Measuring scattering angles with neutron spin echo  

Microsoft Academic Search

We report results of experiments designed to test the use of thin magnetic films as elements of a neutron spin echo (NSE) apparatus for determining neutron scattering angles. We show that 10-?m thin films of Permalloy (Ni0.8 Fe0.2) electrodeposited on silicon wafers function well as ?\\/2 spin rotators. 30?m thick films of the same material used as precession fields in

Michael R Fitzsimmons; Helmut Fritzsche; Marita Gierlings; Janos Major; Roger Pynn

2004-01-01

240

Critical angle in electron capture  

NASA Astrophysics Data System (ADS)

The simultaneous single electron capture and production of doubley-charged He ions in single collisions between fast protons and He atoms has been studied experimentally as a function of scattering angle (0.3-3.2 mrad) and impact energy (200-500 keV). The angular dependences reveal a critical angle at which the probability for production of He++ simultaneously with electron capture peaks sharply. The peak itself as well as the energy dependence of the size and shape of it may be interpreted qualitatively in terms of a capture mechanism proposed already in 1927 by L. H. Thomas on the basis of classical mechanics.

Horsdal, Erik; Jensen, Bente; Nielsen, Karsten Omann

1986-09-01

241

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

242

Tilt angle control of nanocolumns grown by glancing angle sputtering at variable argon pressures  

SciTech Connect

We show that the tilt angle of nanostructures obtained by glancing angle sputtering is finely tuned by selecting the adequate argon pressure. At low pressures, a ballistic deposition regime dominates, yielding high directional atoms that form tilted nanocolumns. High pressures lead to a diffusive regime which gives rise to vertical columnar growth. Monte Carlo simulations reproduce the experimental results indicating that the loss of directionality of the sputtered particles in the gas phase, together with the self-shadowing mechanism at the surface, are the main processes responsible for the development of the columns.

Garcia-Martin, J. M.; Cebollada, A. [IMM-Instituto de Microelectronica de Madrid (CNM-CSIC), Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain); Alvarez, R.; Romero-Gomez, P.; Palmero, A. [Instituto de Ciencia de Materiales de Sevilla, (CSIC-Universidad de Sevilla), Americo Vespucio 49, 41092 Seville (Spain)

2010-10-25

243

ASYMPTOTIC OPENING ANGLES FOR COLLIDING-WIND BOW SHOCKS: THE CHARACTERISTIC-ANGLE APPROXIMATION  

SciTech Connect

By considering the advection and interaction of the vector momentum flux in highly supersonic spherically diverging winds, we derive a simple analytic description of the asymptotic opening angle of a wind-collision shock cone, in the approximation that the shocked gas is contained in a cone streaming out along a single characteristic opening angle. Both highly radiative and highly adiabatic limits are treated, and their comparison is the novel result. Analytic closed-form expressions are obtained for the inferred wind momentum ratios as a function of the observed shock opening angle, allowing the conspicuous shape of the asymptotic bow shock to be used as a preliminary constraint on more detailed modeling of the colliding winds. In the process, we explore from a general perspective the limitations in applying to the global shock geometry the so-called Dyson approximation, which asserts a local balance in the perpendicular ram pressure across the shock.

Gayley, Kenneth G. [University of Iowa, 203 Van Allen Hall, Iowa City, IA 52245 (United States)

2009-09-20

244

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

245

THE ANGLE IRON BAT GATE  

Microsoft Academic Search

This paper discusses the evolution of the American Cave Conservation Association (ACCA) angle iron gate types. Topics discussed include: air flow testing, materials, security, and advantages of these designs. Brief History of Gate Installation Many early gates installed in caves and mines caused more problems and damage to resources than they protected. Airflow disturbances changed temperature and humidity. Paints added

Roy D. Powers Jr

246

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

247

primary open-angle glaucoma  

E-print Network

Purpose: Alterations of the plasmin system have been suggested to participate in the multifactorial pathogenesis of primary open-angle glaucoma (POAG). The main physiological inhibitor of the plasmin system is plasminogen activator inhibitor-1 (PAI-1), which leads to decreased degradation of

Georg Mossböck; Martin Weger; Christoph Faschinger; Otto Schmut; Wilfried Renner

248

Angle interferometer cross axis errors  

Microsoft Academic Search

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

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

1994-01-01

249

The contact angle in inviscid fluid mechanics  

E-print Network

We show that in general, the specification of a contact angle condition at the contact line in inviscid fluid motions is incompatible with the classical field equations and boundary conditions generally applicable to them. The limited conditions under which such a specification is permissible are derived; however, these include cases where the static meniscus is not flat. In view of this situation, the status of the many `solutions' in the literature which prescribe a contact angle in potential flows comes into question. We suggest that these solutions which attempt to incorporate a phenomenological, but incompatible, condition are in some, imprecise sense `weak-type solutions'; they satisfy or are likely to satisfy, at least in the limit, the governing equations and boundary conditions everywhere except in the neighbourhood of the contact line. We discuss the implications of the result for the analysis of inviscid flows with free surfaces.

P N Shankar; R Kidambi

2005-08-17

250

The influence of channel intersection angle on droplets coalescence process  

NASA Astrophysics Data System (ADS)

The present study investigates the influence of channel intersection angle on the droplets coalescence process using high-speed microscope and micro-PIV system. "Spontaneous coalescence" and "delayed coalescence" occur when the droplets meet at low flow rate conditions. The film drainage time and critical capillary number are organized by recording the phenomena after droplets meet at channel junctions with different intersection angles. The microchannel junction structure details are taken for the in-depth understanding of droplets coalescence process. The experimental results show that the critical capillary number for droplets coalescence decreases with the increase of channel intersection angle, and increasing two-phase flow rates and intersection angle can reduce the film drainage time. It can be concluded that reducing the intersection angle may improve the coalescence efficiency.

Liu, Zhaomiao; Cao, Rentuo; Pang, Yan; Shen, Feng

2015-02-01

251

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. PMID:18215305

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

2008-01-01

252

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

253

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

254

Elevation angle dependence of the SMA antenna focus position  

E-print Network

We report the measurement results and compensation of the antenna elevation angle dependences of the Sub-millimeter Array (SMA) antenna characteristics. Without optimizing the subreflector (focus) positions as a function of the antenna elevation angle, antenna beam patterns show lopsided sidelobes, and antenna efficiencies show degradations. The sidelobe level increases and the antenna efficiencies decrease about 1% and a few %, respectively, for every 10 degrees change in the elevation angle at the measured frequency of 237 GHz. We therefore obtained the optimized subreflector positions for X (azimuth), Y (elevation), and Z (radio optics) focus axes at various elevation angles for all the eight SMA antennas. The X axis position does not depend on the elevation angle. The Y and Z axes positions depend on the elevation angles, and are well fitted with a simple function for each axis with including a gravity term (cosine and sine of elevation, respectively). In the optimized subreflector positions, the antenna beam patterns show low level symmetric sidelobe of at most a few %, and the antenna efficiencies stay constant at any antenna elevation angles. Using one set of fitted functions for all antennas, the SMA is now operating with real-time focusing, and showing constant antenna characteristics at any given elevation angle.

Satoki Matsushita; Masao Saito; Kazushi Sakamoto; Todd R. Hunter; Nimesh A. Patel; Tirupati K. Sridharan; Robert W. Wilson

2006-06-21

255

Assessing Mathematics--3. Concepts and Skills: Line Symmetry and Angle.  

ERIC Educational Resources Information Center

Results from an English assessment of achievement on two geometric topics, line symmetry and angles, are reported. Contrasts in the patterns of responses to related items, and to the same items by pupils aged 11 or 15, are highlighted. (MNS)

Foxman, Derek; Ruddock, Graham

1984-01-01

256

Investigating the angle or response and maximum stability of a cohesive granular pile  

E-print Network

In this thesis, I investigate the static and dynamic properties of a granular heap made cohesive by an interstitial fluid. I present the results of experimental work measuring the maximum angle of stability and the angle ...

Nowak, Sara Alice, 1982-

2004-01-01

257

Influences of the interplanetary magnetic field clock angle and cone angle on the field-aligned currents in the magnetotail  

NASA Astrophysics Data System (ADS)

The influences of the interplanetary magnetic field (IMF) cone angle ? and clock angle ? on the field-aligned currents (FACs) at the plasma sheet boundary layers (PSBLs) have been investigated using Cluster Data. The FAC occurrence increases monotonically with IMF cone angle and has two peaks at -90° and +110° clock angle, respectively. The peak at +110° is distinctly larger than that at -90°. Overall, there are more FACs between 0° < ? < 180°, indicating that FACs occurrence is closely associated with duskward IMF. More FACs occur when 90° < |?| < 180°, implying that FAC is closely associated with southward IMF. The large FAC densities occur when 60° < |?| < 120°. The density also has two peaks and the peak at +90° clock angle (duskward IMF) is larger than that at -90° (dawnward IMF). These results indicate that the IMF influence on the FACs is from all IMF components and not only from a single component.

Cheng, Z. W.; Shi, J. K.; Dunlop, M.; Liu, Z. X.

2013-10-01

258

Measurements of integral muon intensity at large zenith angles  

Microsoft Academic Search

Results of the analysis of near-horizontal muons integral intensity data for threshold energies 1.2 - 1.9 GeV measured by means of coordinate detector DECOR in zenith angle interval 61?- 90? are presented. Experimental results for these regions of zenith angles and threshold energies have been obtained for the first time. These data as well as data of other experiments with

A. N. Dmitrieva; D. V. Chernov; R. P. Kokoulin; K. G. Kompaniets; G. Mannocchi; A. A. Petrukhin; O. Saavedra; V. V. Shutenko; D. A. Timaschkov; G. Trinchero; I. I. Yashin

2005-01-01

259

Constraining CKM $\\gamma$ angle at LHCb  

E-print Network

The current combination of all available tree-level measurements of the CKM angle gamma at LHCb is reported. It includes results obtained from time independent analyses of B+ -> DK+ and of B0 -> DK?0 decays; and from a time-dependent analysis of Bs0 -> DsK decays. The results represent the world's best single-experiment determination of gamma. The first observation of the Bs->Ds*K decay and the first observation and amplitude analysis of B- -> D+K-pi- are also reported. In addition to these tree measurements, the estimation of gamma from charmless B meson decay, sensitive to loops contribution, is presented.

Vallier, Alexis Roger Louis

2015-01-01

260

Gaia basic angle monitoring system  

NASA Astrophysics Data System (ADS)

The Gaia mission1 will create an extraordinarily precise three-dimensional map of more than one billion stars in our Galaxy. The Gaia spacecraft2, built by EADS Astrium, is part of ESA's Cosmic Vision programme and scheduled for launch in 2013. Gaia measures the position, distance and motion of stars with an accuracy of 24 micro-arcsec using two telescopes at a fixed mutual angle of 106.5°, named the `Basic Angle', at an operational temperature of 100 K. This accuracy requires ultra-high stability at cryogenic conditions, which can only be achieved by using Silicon Carbide for both the optical bench and the telescopes. TNO has developed, built and space qualified the Silicon carbide Basic Angle Monitoring (BAM) on-board metrology system3 for this mission, measuring the relative motion of Gaia's telescopes with accuracies in the range of 0.5 micro-arcsec. This is achieved by a system of two laser interferometers able to detect Optical Path Differences (OPD) as small as 1.5 picometer rms. Following a general introduction on Gaia and the use of Silicon Carbide as base material this paper addresses the specific challenges towards the cryogenic application of the Gaia BAM including design, integration and verification/qualification by testing.

Gielesen, W.; de Bruijn, D.; van den Dool, T.; Kamphues, F.; Mekking, J.; Calvel, B.; Laborie, A.; Coatantiec, C.; Touzeau, S.; Erdmann, M.; Gare, P.; Monteiro, D.

2013-09-01

261

OPENING ANGLES OF COLLAPSAR JETS  

SciTech Connect

We investigate the jet propagation and breakout from the stellar progenitor for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic hydrodynamic simulations and analytical modeling. We find that the jet opening angle is given by ?{sub j} ? 1/5?{sub 0} and infer the initial Lorentz factor of the jet at the central engine, ?{sub 0}, is a few for existing observations of ?{sub j}. The jet keeps the Lorentz factor low inside the star by converging cylindrically via collimation shocks under the cocoon pressure and accelerates at jet breakout before the free expansion to a hollow-cone structure. In this new picture, the GRB duration is determined by the sound crossing time of the cocoon, after which the opening angle widens, reducing the apparent luminosity. Some bursts violating the maximum opening angle ?{sub j,{sub max}} ? 1/5 ? 12° imply the existence of a baryon-rich sheath or a long-acting jet. We can explain the slopes in both Amati and Yonetoku spectral relations using an off-centered photosphere model, if we make only one assumption that the total jet luminosity is proportional to the initial Lorentz factor of the jet. We also numerically calibrate the pre-breakout model (Bromberg et al.) for later use.

Mizuta, Akira; Ioka, Kunihito [Theory Center, Institute of Particle and Nuclear Studies, KEK, Tsukuba 305-0801 (Japan)

2013-11-10

262

Results and lessons from MODIS reflective solar bands calibration: pre-launch to on-orbit  

NASA Astrophysics Data System (ADS)

MODIS is a major instrument for NASA's EOS missions, currently operating aboard the EOS Terra and Aqua spacecraft launched in December 1999 and May 2002, respectively. It was designed to extend heritage sensor measurements and data records and to enable new research studies of the Earth's land, oceans, and atmosphere. MODIS has 36 spectral bands (0.41 - 14.4?m) located on four focal plane assemblies (FPA). It makes measurements at three nadir spatial resolutions: 0.25km, 0.5km, and 1km. Because of instrument design complexity and more stringent calibration requirements, extensive calibration and characterization activities were conducted pre-launch by the sensor vendor for both Terra and Aqua MODIS. For the 20 reflective solar bands (RSB) with wavelengths below 2.2?m, these activities include detector noise characterization, radiometric response at different instrument temperatures and at different scan angles, and relative spectral response. On-orbit RSB calibration is performed using a solar diffuser (SD) and a solar diffuser stability monitor (SDSM). In addition, regular lunar observations are made to track RSB radiometric stability. This paper provides a summary of Terra and Aqua MODIS RSB pre-launch and on-orbit calibration and characterization activities, methodologies, data analysis results, and lessons learned. It focuses on major issues that could impact MODIS RSB calibration and data product quality. Results presented in this paper include RSB detector noise characterization, response versus scan angle and instrument temperature, SD bi-directional reflectance factors characterization, and on orbit calibration stability. Similar discussions on MODIS thermal emissive bands (TEB) are presented in a separate paper in these proceedings (Xiong et. al).

Xiong, X.; Che, N.; Pan, C.; Xie, X.; Sun, J.; Barnes, W. L.; Guenther, B.

2006-08-01

263

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

264

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

265

Recent 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 the roll and pitch attitude based on the Earth Sensor Assembly (ESA) output. TRMM's nominal orbit altitude was 350 km, until raised to 402 km to prolong mission life. During the boost, the ESA experienced a decreasing signal to noise ratio, until sun interference at 393 km altitude made the ESA data unreliable for attitude determination. At that point, the backup attitude determination algorithm, an extended Kalman filter, was enabled. After the boost finished, TRMM reacquired its nadir-pointing attitude, and continued its mission. This paper will briefly discuss the boost and the decision to turn on the backup attitude determination algorithm. A description of the extended Kalman filter algorithm will be given. In addition, flight results from analyzing attitude data and the results of software changes made onboard TRMM will be discussed. Some lessons learned are presented.

Andrews, Stephen F.; Bilanow, Stephen; Bauer, Frank (Technical Monitor)

2002-01-01

266

A reevaluation of Stogryn's apparent temperature theory over the sea surface  

NASA Technical Reports Server (NTRS)

The emission theory for the sea surface by Stogryn has been reevaluated. Results agree with Stogryn's paper except for small nadir angles where the apparent temperature versus wind speed behavior is in reverse of what was reported by Stogryn. By plotting the change in contributions by the sea surface emission and sky temperature scattered toward the radiometer as a function of nadir angle at two different wind speeds, it is found that the sky temperature effect is dominating at small nadir angles, while the change in surface emission becomes increasingly more important at larger nadir angles. It is also found that at nadir higher emission is associated with the polarization where E(arrow) field is aligned along the upwind direction than the one along the crosswind direction.

Fung, A. K.; Eom, H. J.

1984-01-01

267

Cardiopulmonary Responses at Various Angles of Cycle Backrest Inclination  

PubMed Central

The purpose of this study was to evaluate cardiopulmonary responses during submaximal cycle exercise at various angles of backrest inclination. Ten healthy Japanese men of mean age 25.9 yrs, height 170.6 cm, and body mass 66.1 kg, performed cycle exercises at a constant workload which reached the anaerobic threshold, at 20 degrees, 40 degrees, and 60 degrees of backrest inclination from the vertical plane, but the angle between the seat and back rest was kept at 110 degrees. The results were as follows: 1) Both cardiac output and stroke volume showed a higher value at the resting control state and during exercise as the backrest angle increased. 2) Oxygen consumption, carbon dioxide output, heart rate, gas exchange ratio, and oxygen pulse were not affected by the angle of backrest inclination. 3) Tidal volume at 20 degrees of backrest inclination was higher than at 60 degrees. 4) No significant differences were found in minute ventilation between each backrest angle. These findings suggest that changes in the backrest angle significantly alter cardiopulmonary parameters at rest and during exercise; in particular, an angle difference of 40 degrees may be enough to alter tidal volume, cardiac output and stroke volume, but not the minute ventilation.

Yamada, Sumio; Tanabe, Kazuhiko; Izawa, Kazuhiro; Itoh, Haruki; Murayama, Masahiro

1999-01-01

268

Autonomous flight test using angle of UAV’s velocity vector  

Microsoft Academic Search

This paper describes the result of the guidance using the heading angle from the magnetic heading vector and velocity vector when autonomous flight is performed by the point navigation guidance. The guidance logic makes difference between the line of sight angle and UAVpsilas heading angle as an error using PD controller. In fixed-wing, the accuracy of convergence is influenced by

Dong-in Han; Jong-hun Kim; Dae-woo Lee; Kyum-rae Cho; Sung-jin Cho

2008-01-01

269

Measurements of integrated muon intensity at large zenith angles  

Microsoft Academic Search

Data from the DECOR coordinate detector on the integrated intensity of muons that have a threshold energy of 1.2 to 2 GeV\\u000a are analyzed over the zenith-angle interval 60°–90°. Experimental results in these intervals of zenith angles and threshold\\u000a energies were obtained for the first time. In the interval ? ? 80°, the integrated intensity at E\\u000a min = 1.5

A. N. Dmitrieva; R. P. Kokoulin; K. G. Kompaniets; A. A. Petrukhin; O. Saavedra; D. A. Timashkov; D. V. Chernov; V. V. Shutenko; I. I. Yashin; G. Trinchero

2006-01-01

270

Measurements of the integrated muon intensity at large zenith angles  

Microsoft Academic Search

Precision measurements of the zenith-angle distributions of muons in the range 61°–89° are performed using the DECOR coordinate\\u000a detector. The total number of selected events is more than 20 million. The dependence of the integrated muon intensity on\\u000a the zenith angle is determined for several threshold energies in the range from 1.7 to 7.2. GeV. The experimental results\\u000a in these

A. N. Dmitrieva; R. P. Kokoulin; K. G. Kompaniets; G. Mannocchi; A. A. Petrukhin; O. Saavedra; D. A. Timashkov; G. Trinchero; D. V. Chernov; V. V. Shutenko; I. I. Yashin

2007-01-01

271

Modeling of 3-D Angle-Interlock Textile Structural Composites  

Microsoft Academic Search

A model is developed to predict the in-plane elastic properties of compos ites reinforced with 3-D angle-interlock textile preforms. Straight yarn segments and microcells are utilized in a lamination analogy to predict the in-plane elastic constants. Numerical results for angle-interlock preforms are compared to preliminary test data available in the literature. The effects of varying geometric parameters, namely crimp in

Thomas J. Whitney; Tsu-Wei Chou

1989-01-01

272

SU-E-I-56: Scan Angle Reduction for a Limited-Angle Intrafraction Verification (LIVE) System  

SciTech Connect

Purpose: To develop a novel adaptive reconstruction strategy to further reduce the scanning angle required by the limited-angle intrafraction verification (LIVE) system for intrafraction verification. Methods: LIVE acquires limited angle MV projections from the exit fluence of the arc treatment beam or during gantry rotation between static beams. Orthogonal limited-angle kV projections are also acquired simultaneously to provide additional information. LIVE considers the on-board 4D-CBCT images as a deformation of the prior 4D-CT images, and solves the deformation field based on deformation models and data fidelity constraint. LIVE reaches a checkpoint after a limited-angle scan, and reconstructs 4D-CBCT for intrafraction verification at the checkpoint. In adaptive reconstruction strategy, a larger scanning angle of 30° is used for the first checkpoint, and smaller scanning angles of 15° are used for subsequent checkpoints. The onboard images reconstructed at the previous adjacent checkpoint are used as the prior images for reconstruction at the current checkpoint. As the algorithm only needs to reconstruct the small deformation occurred between adjacent checkpoints, projections from a smaller scan angle provide enough information for the reconstruction. XCAT was used to simulate tumor motion baseline drift of 2mm along sup-inf direction at every subsequent checkpoint, which are 15° apart. Adaptive reconstruction strategy was used to reconstruct the images at each checkpoint using orthogonal 15° kV and MV projections. Results: Results showed that LIVE reconstructed the tumor volumes accurately using orthogonal 15° kV-MV projections. Volume percentage differences (VPDs) were within 5% and center of mass shifts (COMS) were within 1mm for reconstruction at all checkpoints. Conclusion: It's feasible to use an adaptive reconstruction strategy to further reduce the scan angle needed by LIVE to allow faster and more frequent intrafraction verification to minimize the treatment errors in lung cancer treatments. Grant from Varian Medical System.

Ren, L; Zhang, Y; Yin, F [Duke University Medical Center, Durham, NC (United States)

2014-06-01

273

Analysis of Ku-band cross section at low incidence angles  

NASA Technical Reports Server (NTRS)

This study is using airborne Ku-band data to address questions which have implications for both model function development and for advancing our physical understanding of the sea surface. Concurrent measurements of ocean directional spectra, significant wave height, and mean surface roughness are made using the capabilities of the radar ocean wave spectrometer (ROWS). The NASA/GSFC's ROWS is a 15 GHz pulse compressed radar which is a radar sensor designed to measure the direction of the long wave components using spectral analysis of the tilt induced reflectively modulation. The ROWS are modified to cycle at 50 Hz for the scanning spectrometer antenna and a wide beamwidth nadir altimeter mode. This change allows the sensor to simultaneously measure directional wave spectra, wave height, mean square slope parameter, and small scale surface roughness. The surface stress caused by the wind is widely believed to be the predominant quantity related to the Ku-band radar cross section for a wide range of incidence angles. The complete coverage in the quasi specular region provided by one sensor is essential to understand the uncertainties between the scattering model and what is happening on the surface. For this presentation, special attention is devoted to sort out some measurement of the anisotropy associated with the band of high frequencies. Using the other geophysical parameters, comparisons are then made with the classic spectral form currentlyused to describe the wind impact on the sea surface.

Chapron, B.; Vandemark, D.

1993-01-01

274

Incorporation of appropriate contact angles in textural characterization by mercury porosimetry  

Microsoft Academic Search

In this paper the application of the measured contact angle in textural characterization of porous solids by mercury intrusion porosimetry (MIP) has been investigated. The contact angle of mercury on various materials was measured by the advancing angle and static angle methods. Both methods led to very similar and reproducible results. Most oxidic materials, including Al2O3, SiO2, and TiO2, and

J. C. Groena; L. A. A. Peffer; J. Pérez-Ramírez

2002-01-01

275

Amplitude-versus-angle analysis and wide-angle-inversion of crosswell seismic data in a carbonate reservoir  

NASA Astrophysics Data System (ADS)

Crosswell data set contains a range of angles limited only by the geometry of the source and receiver configuration, the separation of the boreholes and the depth to the target. However, the wide angles reflections present in crosswell imaging result in amplitude-versus-angle (AVA) features not usually observed in surface data. These features include reflections from angles that are near critical and beyond critical for many of the interfaces; some of these reflections are visible only for a small range of angles, presumably near their critical angle. High-resolution crosswell seismic surveys were conducted over a Silurian (Niagaran) reef at two fields in northern Michigan, Springdale and Coldspring. The Springdale wells extended to much greater depths than the reef, and imaging was conducted from above and from beneath the reef. Combining the results from images obtained from above with those from beneath provides additional information, by exhibiting ranges of angles that are different for the two images, especially for reflectors at shallow depths, and second, by providing additional constraints on the solutions for Zoeppritz equations. Inversion of seismic data for impedance has become a standard part of the workflow for quantitative reservoir characterization. Inversion of crosswell data using either deterministic or geostatistical methods can lead to poor results with phase change beyond the critical angle, however, the simultaneous pre-stack inversion of partial angle stacks may be best conducted with restrictions to angles less than critical. Deterministic inversion is designed to yield only a single model of elastic properties (best-fit), while the geostatistical inversion produces multiple models (realizations) of elastic properties, lithology and reservoir properties. Geostatistical inversion produces results with far more detail than deterministic inversion. The magnitude of difference in details between both types of inversion becomes increasingly pronounced for thinner reservoirs, particularly those beyond the vertical resolution of the seismic. For any interface imaged from above and from beneath, the results AVA characters must result from identical contrasts in elastic properties in the two sets of images, albeit in reverse order. An inversion approach to handle both datasets simultaneously, at pre-critical angles, is demonstrated in this work. The main exploration problem for carbonate reefs is determining the porosity distribution. Images of elastic properties, obtained from deterministic and geostatistical simultaneous inversion of a high-resolution crosswell seismic survey were used to obtain the internal structure and reservoir properties (porosity) of Niagaran Michigan reef. The images obtained are the best of any Niagaran pinnacle reef to date.

Ibrahim, Mohamed S.

276

[Statistical evaluation of the "measure of concordance" between Angle classifications and the ANB angle].  

PubMed

In a sample of 177 subjects 6 to 15 years of age, with various types and degrees of malocclusions, the A.A. measured, with statistical methods, the agreement between Angle and Ballard classifications. The result was a disagreement between the two classifications for Class I and Class II malocclusion and some agreement between the two classifications for Class III malocclusion. The applied discriminant function was not able to classify observations in a better way. PMID:2637407

Antonini, A; Marchi, M; Di Tante, M; Zanobetti, A

1989-01-01

277

The Complex Angle in Normed Spaces  

NASA Astrophysics Data System (ADS)

We consider a generalized angle in complex normed vector spaces. Its definition corresponds to the definition of the well known Euclidean angle in real inner product spaces. Not surprisingly it yields complex values as 'angles'. This 'angle' has some simple properties, which are known from the usual angle in real inner product spaces. But to do ordinary Euclidean geometry real angles are necessary. We show that even in a complex normed space there are many pure real valued 'angles'. The situation improves yet in inner product spaces. There we can use the known theory of orthogonal systems to find many pairs of vectors with real angles, and to do geometry which is based on the Greeks 2000 years ago.

Thürey, Volker

2014-03-01

278

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

279

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.

280

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

281

Neptune high-latitude emission: Dependence of angle on frequency  

NASA Technical Reports Server (NTRS)

Smooth broadband radio emission reached a maximum and then cut off as Voyager approached the north magnetic pole of Neptune. The time of each event depends on frequency, yielding information on radio source location, and emission angle. In a preliminary analysis L-shell and magnetic longitude define radio-source locations in a dipole field. The emission angle at each frequency is identified with the angle between the magnetic-field direction at the source and the line of sight to Voyager 2 at the time of emission maximum. At each value of L in the range 6 less than L less than 9, there is one source longitude for which emission angle varies smoothly from greater or equal to 90 deg at 40 kHz to as low as 20 deg at 462 kHz. A more complex magnetic-field model can give a qualitatively different result.

Sawyer, Constance

1993-01-01

282

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

283

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.

284

Compositive effects of orientation and contact angle on critical heat flux in pool boiling of water  

NASA Astrophysics Data System (ADS)

An experimental study was carried out to investigate the effects of heat transfer surface orientation and the solid-liquid contact angle on the boiling heat transfer and critical heat flux (CHF) in water pool boiling using a smooth heat-transfer surface under atmospheric pressure. The orientation angle was ranged from 0° (up-facing horizontal position) to 180° (down-facing horizontal position) with a pace of 45°. The three kinds of heat transfer surfaces having different solid-liquid contact angles were the normal surface with a contact angle of 55°, the hydrophilic surface with a contact angle of 30° and the superhydrophilic surface with a contact angle of 0°. The experimental results indicate that orientation and contact angle have complex, coupling effects on heat transfer and CHF. A predicting correlation for the CHF which takes the effects of both orientation and contact angle into account is established. The predicting correlation agrees reasonably well with the experimental data.

Liao, Liang; Bao, Ran; Liu, Zhenhua

2008-10-01

285

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

286

Creation of the pi angle standard for the flat angle measurements  

Microsoft Academic Search

Angle measurements are based mainly on multiangle prisms - polygons with autocollimators, rotary encoders fo high accuracy and circular scales as the standards of the flat angle. Traceability of angle measurements is based on the standard of the plane angle - prism (polygon) calibrated at an appropriate accuracy. Some metrological institutions have established their special test benches (comparators) equipped with

V. Giniotis; M. Rybokas

2010-01-01

287

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

288

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

289

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

290

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

291

Measured and calculated effects of angle of attack on the transonic flutter of a supercritical wing  

NASA Technical Reports Server (NTRS)

The effects of angle of attack between 0 and 4 degrees were studied. The results indicate that increasing angle of attack from zero can produce substantial changes in the transonic flutter characteristics that are favorable or unfavorable depending on Mach number and angle of attack. The bottom of the transonic flutter-boundary 'bucket' is shown to occur at lower Mach number as angle of attack increases. These flutter results correlate well with the effects of Mach number and angle of attack on aerodynamic behavior, especially on the development of transonic flow phenomena. The calculated flutter characteristics are in good agreement with the experimental data at zero angle of attack, but at nonzero angles of attack the experiments show sharply declining and backward-turning transonic flutter boundaries that are not indicated by the calculations. These may be caused by variations in static aeroelastic deformation.

Yates, E. C., Jr.; Wynne, E. C.; Farmer, M. G.

1982-01-01

292

Survival probability of a Brownian motion in a planar wedge of arbitrary angle  

NASA Astrophysics Data System (ADS)

We study the survival probability and the first-passage time distribution for a Brownian motion in a planar wedge with infinite absorbing edges. We generalize existing results obtained for wedge angles of the form ? /n with n a positive integer to arbitrary angles, which in particular cover the case of obtuse angles. We give explicit and simple expressions of the survival probability and the first-passage time distribution in which the difference between an arbitrary angle and a submultiple of ? is contained in three additional terms. As an application, we obtain the short-time development of the survival probability in a wedge of arbitrary angle.

Chupeau, Marie; Bénichou, Olivier; Majumdar, Satya N.

2015-03-01

293

Submillimetre polarimetric observations of S140 and GL 2591: investigating the role of viewing angle on observed polarization position angles.  

NASA Astrophysics Data System (ADS)

We have measured the 800?m polarization at three positions towards S140 and at the flux peak towards GL 2591. For both sources the implied magnetic field direction is neither parallel nor perpendicular to the outflow axis, implying an "in-between" situation. A review of published submillimetre polarimetric observations of outflow sources implies this scenario is common. Whilst beamsize effects are not thought to be critical, comparison of these observations with the results from a recent theoretical model (Bonifacio & Emerson 1995, ASP Conf. Ser., 97, 363) imply that the "in-between" situations may actually be due to the effect of viewing angle on the observed polarization position angle. If the local magnetic field is uniform and perpendicular to the outflow axis the observed position angle of polarization for dichroic emission of aligned grains is highly dependent on the viewing angle. The surprising agreement between mid-infrared and submillimetre emissive polarization position angles for W3-IRS5, NGC 7538-IRS1 and OMC1-IRc2, and their non-orthogonality to the mid-IR absorptive polarization position angles, has implications for the magnetic field configuration around these outflow sources. In particular, an hour-glass magnetic field geometry may be applicable.

Minchin, N. R.; Bonifacio, V. H. R.; Murray, A. G.

1996-11-01

294

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

295

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

296

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

297

A superconducting large-angle magnetic suspension  

NASA Astrophysics Data System (ADS)

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.

1992-12-01

298

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

299

Algorithms For Limited-Angle Computed Tomography  

NASA Astrophysics Data System (ADS)

Limited-angle computed tomography was studied in a project to develop algorithms for a limited-angle scanner. Both the ART algorithm and an orthogonal function algorithm were investigated. The artifact produced by the different methods was very similar. A method is presented for producing model limited-angle artifact in phantom images. Filters are investigated for reducing the artifact, and it is shown that substantial improvement in subjective quality of images can be obtained. This method can be incorporated into limited-angle convolution back-projection algorithms.

Rowan, William H.; Boyd, Douglas P.; Couch, John L.; Ortendahl, Douglas

1982-11-01

300

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

301

Dynamical deformed Airy beams with arbitrary angles between two wings.  

PubMed

We study both numerically and experimentally the acceleration and propagation dynamics of 2D Airy beams with arbitrary initial angles between their "two wings." Our results show that the acceleration of these generalized 2D Airy beams strongly depends on the initial angles and cannot be simply described by the vector superposition principle (except for the normal case of a 90° angle). However, as a result of the "Hyperbolic umbilic" catastrophe (a two-layer caustic), the main lobes of these 2D Airy beams still propagate along parabolic trajectories even though they become highly deformed. Under such conditions, the peak intensity (leading energy flow) of the 2D Airy beams cannot be confined along the main lobe, in contrast to the normal 90° case. Instead, it is found that there are two parabolic trajectories describing the beam propagation: one for the main lobe, and the other for the peak intensity. Both trajectories can be readily controlled by varying the initial wing angle. Due to their self-healing property, these beams tend to evolve into the well-known 1D or 2D Airy patterns after a certain propagation distance. The theoretical analysis corroborates our experimental observations, and explains clearly why the acceleration of deformed Airy beams increases with the opening of the initial wing angle. PMID:25121433

Liang, Yi; Hu, Yi; Ye, Zhuoyi; Song, Daohong; Lou, Cibo; Zhang, Xinzheng; Xu, Jingjun; Morandotti, Roberto; Chen, Zhigang

2014-07-01

302

Angle effect in laser nanopatterning with particle-mask  

NASA Astrophysics Data System (ADS)

Parallel nanostructuring of substrate surface with particle-mask is a promising technology that may significantly improve the patterning speed under single laser pulse irradiation. In this paper, the influence of the incidence wave angle on the pattern structures is investigated. Polystyrene spherical particles were deposited on the surface in a monolayer form by self-assembly. The sample was then irradiated with 248nm KrF laser at different incidence angles ?. It is found that nanostructures can be formed at different positions with different incidence angles. Both round-shape and comet-shape nanostructures can be produced. By varying the incidence angles, the depth of the nanostructures can also be controlled. To explain the different nanostructures produced at different angles, the intensity field distributions under the particle were calculated according to an exact model for light scattering by a sphere on the substrate (P. A. Bobbert and J. Vlieger, Physica A 137A, 209 1986). The main equation in the original model was reformed for the ease of numerical simulation. A method was proposed to calculate the total electric and magnetic field as an extension to the model. The theoretical results are in good agreement with the experimental results.

Wang, Z. B.; Hong, M. H.; Luk'yanchuk, B. S.; Lin, Y.; Wang, Q. F.; Chong, T. C.

2004-12-01

303

Real-Time Aerodynamic Parameter Estimation without Air Flow Angle Measurements  

NASA Technical Reports Server (NTRS)

A technique for estimating aerodynamic parameters in real time from flight data without air flow angle measurements is described and demonstrated. The method is applied to simulated F-16 data, and to flight data from a subscale jet transport aircraft. Modeling results obtained with the new approach using flight data without air flow angle measurements were compared to modeling results computed conventionally using flight data that included air flow angle measurements. Comparisons demonstrated that the new technique can provide accurate aerodynamic modeling results without air flow angle measurements, which are often difficult and expensive to obtain. Implications for efficient flight testing and flight safety are discussed.

Morelli, Eugene A.

2010-01-01

304

Determination of the position angle of stellar spin axes  

NASA Astrophysics Data System (ADS)

Context. Measuring the stellar position angle provides valuable information on binary stellar formation or stellar spin axis evolution. Aims: We aim to develop a method for determining the absolute stellar position angle using spectro-astrometric analysis of high resolution long-slit spectra. The method has been designed in particular for slowly rotating stars. We investigate its applicability to existing dispersive long-slit spectrographs, identified here by their plate scale, and the size of the resulting stellar sample. Methods: The stellar rotation induces a tilt in the stellar lines whose angle depends on the stellar position angle and the orientation of the slit. We developed a rotation model to calculate and reproduce the effects of stellar rotation on unreduced high resolution stellar spectra. Then we retrieved the tilt amplitude using a spectro-astrometric extraction of the position of the photocentre of the spectrum. Finally we present two methods for analysing the position spectrum using either direct measurement of the tilt or a cross-correlation analysis. Results: For stars with large apparent diameter and using a spectrograph with a small plate scale, we show that it is possible to determine the stellar position angle directly within 10° with a signal-to-noise ratio of the order of 6. Under less favourable conditions, i.e. larger plate scale or smaller stellar diameter, the cross-correlation method yields comparable results. Conclusions: We show that with the currently existing instruments, it is possible to determine the stellar position angle of at least 50 stars precisely, mostly K-type giants with apparent diameter down to 5 milliarcseconds. If we consider errors of around 10° still acceptable, we may include stars with apparent diameter down to 2 mas in the sample that then comprises also some main sequence stars.

Lesage, A.-L.; Wiedemann, G.

2014-03-01

305

for Chronic Open Angle Glaucoma by UK  

E-print Network

Myint, Joy (2013). A study of case finding for chronic open angle glaucoma by UK community optometrists. (Unpublished Doctoral thesis, City University London) City Research Online Original citation: Myint, Joy (2013). A study of case finding for chronic open angle glaucoma by UK community

Community Optometrists; Joy Myint

306

Vision only Presented angle (Visual / Body)  

E-print Network

Vision only Presented angle (Visual / Body) 45º / 30º 60º / 40º 75º / 50º Reproductedrotationangle rotation Vision + Body (same gain) Presented angle (Visual / Body) 45º / 30º 60º / 40º 75º / 50º Reproductedrotationangle(º) 0 10 20 30 40 50 60 70 80 Visual rotation Body rotation Vision + Body (different gain

307

Let's Do It! Using Geostrips and "Angle-Fixers" to Develop Ideas About Shapes and Angles  

ERIC Educational Resources Information Center

Homemade geostrips, "angle-fixers" (cardboard circular sectors) and brass fasteners can be used by students to explore properties of angles, triangles and other polygons. Several games and other activities are suggested. (SD)

Bruni, James V.; Silverman, Helene

1975-01-01

308

Contact angle measurements with liquids consisting of bulky molecules.  

PubMed

Well-measured contact angles with different solid-liquid systems fall approximately on smooth patterns when plotted versus liquid surface tension. However, there are deviations of 1 degrees -3 degrees , which are outside the error limits. It is the purpose of this paper to elucidate the reasons for such deviations. Two types of liquids were selected for advancing contact angle measurements on Teflon AF 1600 coated surfaces: a series of n-alkanes ranging from n-hexane to n-hexadecane and five liquids consisting of bulky molecules, octamethylcyclotetrasiloxane (OMCTS), methyl salicylate, tetralin, cis-decalin, and octamethyltrisiloxane (OMTS). It was found that contact angles of the liquids with bulky molecules fall on a perfectly smooth curve corresponding to a solid surface tension of 13.64 +/- 0.1 mJ/m2. However, contact angles of n-alkanes deviated from this curve by up to 3 degrees in a complicated fashion. The observed trend suggests that more than one mechanism is responsible for the deviations. Substrate-induced rearrangement of liquid molecules in the close vicinity of the surface in the case of long-chain n-alkanes and adsorption of vapor onto the solid surface in the case of short-chain n-alkanes are the most likely explanations. The results suggest that liquids with bulky molecules appear to be suitable for contact angle measurements to characterize energetics of polymeric surfaces. PMID:15464816

Tavana, H; Lam, C N C; Grundke, K; Friedel, P; Kwok, D Y; Hair, M L; Neumann, A W

2004-11-15

309

Use of angle kappa in myopic photorefractive keratectomy  

PubMed Central

Purpose To explore utilization of the coaxially sighted corneal light reflex (CSCLR) for centration during myopic photorefractive keratectomy (PRK) for patients with relatively high angle kappa (?) values. Methods Patients were stratified into two groups preoperatively, on the basis of angle ? values. Group A was composed of 166 eyes with an angle ? value <5°. Group B consisted of 182 eyes with an angle ? value >5°. Intraoperative centering of ablation was performed within group A by utilizing the pupillary center, and within group B by using the CSCLR. Visual acuities were evaluated and compared at 6 months and 12 months postoperatively between groups. Results Mean uncorrected visual acuities (UCVA) for all patients at 6 months and 12 months were ?0.073 logMAR and ?0.080 logMAR, respectively. A total of 98.9% of patients had a UCVA of 0.00 logMAR (?20/20 Snellen) 12 months postoperatively. There was not a significant between-group difference in regard to residual refractive error at 6 months or 12 months (P=0.53 and P=0.97), or in UCVA at 6 months and 12 months (P=0.76 and P=0.17). There were no subjective complaints of monocular diplopia, glare, or haloes within either group at any time during follow-up. Conclusion Availing use of the CSCLR for centration of ablation within myopic patients with high angle ? values may aid in providing better refractive outcomes after performance of PRK. PMID:25678767

Khakshoor, Hamid; McCaughey, Michael V; Vejdani, Amir Hossein; Daneshvar, Ramin; Moshirfar, Majid

2015-01-01

310

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

311

Angle of Arrival Detection with Fifth Order Phase Operators  

E-print Network

In this paper, a fifth order propagator operators are proposed for estimating the Angles Of Arrival (AOA) of narrowband electromagnetic waves impinging on antenna array when its number of sensors is larger than the number of radiating sources. The array response matrix is partitioned into five linearly dependent phases to construct the noise projector using five different propagators from non diagonal blocks of the spectral matrice of the received data; hence, five different estimators are proposed to estimate the angles of the sources. The simulation results proved the performance of the proposed estimators in the presence of white noise comparatively to high resolution eigen based spectra.

Khmou, Youssef

2015-01-01

312

Magic angles and cross-hatching instability in hydrogel fracture.  

PubMed

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. PMID:18518345

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

2008-05-01

313

Magic angles and cross-hatching instability in hydrogel fracture  

E-print Network

The full 2D analysis of roughness profiles of fracture surfaces resulting from quasi-static crack propagation in gelatin gels reveals an original behavior characterized by (i) strong anisotropy with maximum roughness at $V$-independent symmetry-preserving angles, (ii) a sub-critical 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 that low strain moduli.

Tristan Baumberger; Christiane Caroli; David Martina; Olivier Ronsin

2008-02-29

314

Design the diffractive optical element with large diffraction angle  

NASA Astrophysics Data System (ADS)

In this paper, a quite effective method is proposed for designing the diffractive optical element (DOE) to generate a pattern with large diffraction angle. Through analyze the difference between the non-paraxial Rayleigh Sommerfeld integral and the paraxial Fraunhofer diffraction integral, we modify the desired output intensity distribution with coordinate transformation and intensity adjustment. Then the paraxial Fraunhofer diffraction integral can be used to design the DOE, which adopts the fast-Fourier-transform (FFT) algorithm to accelerate the computation. To verify our method, the simulation and the experiments are taken. And the result shows that our method can effectively rectify the pillow distortion and can achieve the exact diffraction angle.

Pang, Hui; Yin, Shaoyun; Zheng, Guoxing; Deng, Qiling; Shi, Lifang; Du, Chunlei

2014-11-01

315

Angle resolved color of bulk scattering media.  

PubMed

The angle resolved reflectance factor of matte samples is measured with a goniophotometer and simulated using radiative transfer theory. Both measurements and simulations display the same characteristic dependence of the reflectance factor on the observation angle. The angle resolved reflectance spectra are translated to CIELAB color coordinates and the angular color differences are found to be surprisingly large. A chromatic adaptation that is dependent on the observation angle is suggested, in which a nonabsorbing opaque medium is used as the reference white, and the angular color differences are then reduced. Furthermore, the use of an undyed paper as the reference white is evaluated. The angular lightness differences are then reduced further, but the angular differences in chroma are still large. It is suggested that smaller variations in perceived color could be explained by angle dependent chromatic adaptation and a limited sensitivity of the human visual system to changes in chroma. PMID:22193184

Neuman, Magnus; Coppel, Ludovic G; Edström, Per

2011-12-20

316

Guidance law against maneuvering targets with intercept angle constraint.  

PubMed

This study explores the guidance law against maneuvering targets with the intercept angle constraint. The limitation of the traditional guidance law, which simply treats the unknown target acceleration as zero, has been analyzed. To reduce this limitation, a linear extended state observer is constructed to estimate the acceleration of the maneuvering target to enhance the tracking performance of the desired intercept angle. Furthermore, a nonsingular terminal sliding mode control scheme is adopted to design the sliding surface, which is able to avoid the singularity in the terminal phase of guidance. Simulation results have demonstrated that the proposed guidance law outperforms the traditional guidance law in the sense that more accurate intercept angle can be achieved. PMID:24773919

Xiong, Shaofeng; Wang, Weihong; Liu, Xiaodong; Wang, Sen; Chen, Zengqiang

2014-07-01

317

Measurements of integrated muon intensity at large zenith angles  

SciTech Connect

Data from the DECOR coordinate detector on the integrated intensity of muons that have a threshold energy of 1.2 to 2 GeV are analyzed over the zenith-angle interval 60{sup o}-90{sup o}. Experimental results in these intervals of zenith angles and threshold energies were obtained for the first time. In the interval {theta} {<=} 80{sup o}, the integrated intensity at E{sub min} = 1.5 GeV as a function of the cosine of the zenith angle is described by a power-law function characterized by an exponent value of n = 1.884 {+-} 0.005, which is close to the value obtained in earlier experiments.

Dmitrieva, A. N., E-mail: ANDmitrieva@mephi.ru; Kokoulin, R. P.; Kompaniets, K. G.; Petrukhin, A. A. [Moscow Engineering Physics Institute (State University) (Russian Federation); Saavedra, O. [Dipartimento di Fisica Generale dell'Universita di Torino (Italy); Timashkov, D. A.; Chernov, D. V.; Shutenko, V. V.; Yashin, I. I. [Moscow Engineering Physics Institute (State University) (Russian Federation)

2006-05-15

318

Correlating lepton mixing angles and mixing maxtrix with Wolfenstein parameters  

NASA Astrophysics Data System (ADS)

Inspired by a new relation ?13PMNS=?C/2 observed from the relatively large ?13PMNS, we find that the combination of this relation with the quark-lepton complementarity and the self-complementarity results in correlations of the lepton mixing angles with the quark mixing angles. We find that the three mixing angles in the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix are all related to the Wolfenstein parameter ? in the quark mixing, so they are also correlated. Consequently, the PMNS matrix can be parameterized by ?, A, and a Dirac CP-violating phase ?. Such parametrizations for the PMNS matrix have the same explicitly hierarchical structure as the Wolfenstein parametrization for the Cabibbo-Kobayashi-Maskawa matrix in the quark mixing, and the bimaximal mixing pattern is deduced at the leading order. We also discuss implications of these phenomenological relations in parametrizations.

Zhang, Xinyi; Ma, Bo-Qiang

2012-11-01

319

Measurements of CKM Angle Beta from BaBar  

SciTech Connect

We present recent results of hadronic B meson decays related to the CKM angle beta. The data used were collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider operating at the Upsilon(4S) resonance located at the Stanford Linear Accelerator Center.

Ulmer, Keith A.; /Colorado U.

2007-05-23

320

Measurements of the angle alpha (phi2) at B factories  

E-print Network

The measurements of the angle alpha (phi2) of the unitarity triangle at the B factories are reviewed. The value of alpha determined by combining the results obtained in the B to pi pi, B to rho pi, and B to rho rho modes by both the BABAR and Belle experiments is (87.5 +6.2 -5.3) degrees.

G. Vasseur

2008-10-02

321

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

322

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

323

Uncertainty incorporated beam angle optimization for IMPT treatment planning  

PubMed Central

Purpose: Beam angle optimization (BAO) by far remains an important and challenging problem in external beam radiation therapy treatment planning. Conventional BAO algorithms discussed in previous studies all focused on photon-based therapies. Impact of BAO on proton therapy is important while proton therapy increasingly receives great interests. This study focuses on potential benefits of BAO on intensity-modulated proton therapy (IMPT) that recently began available to clinical cancer treatment. Methods: The authors have developed a novel uncertainty incorporated BAO algorithm for IMPT treatment planning in that IMPT plan quality is highly sensitive to uncertainties such as proton range and setup errors. A linear programming was used to optimize robust intensity maps to scenario-based uncertainties for an incident beam angle configuration. Unlike conventional intensity-modulated radiation therapy with photons (IMXT), the search space for IMPT treatment beam angles may be relatively small but optimizing an IMPT plan may require higher computational costs due to larger data size. Therefore, a deterministic local neighborhood search algorithm that only needs a very limited number of plan objective evaluations was used to optimize beam angles in IMPT treatment planning. Results: Three prostate cancer cases and two skull base chordoma cases were studied to demonstrate the dosimetric advantages and robustness of optimized beam angles from the proposed BAO algorithm. Two- to four-beam plans were optimized for prostate cases, and two- and three-beam plans were optimized for skull base cases. By comparing plans with conventional two parallel-opposed angles, all plans with optimized angles consistently improved sparing at organs at risks, i.e., rectum and femoral heads for prostate, brainstem for skull base, in either nominal dose distribution or uncertainty-based dose distributions. The efficiency of the BAO algorithm was demonstrated by comparing it with alternative methods including simulated annealing and genetic algorithm. The numbers of IMPT plan objective evaluations required were reduced by up to a factor of 5 while the same optimal angle plans were converged in selected comparisons. Conclusions: Uncertainty incorporated BAO may introduce pronounced improvement of IMPT plan quality including dosimetric benefits and robustness over uncertainties, based on the five clinical studies in this paper. In addition, local search algorithms may be more efficient in finding optimal beam angles than global optimization approaches for IMPT BAO. PMID:22894449

Cao, Wenhua; Lim, Gino J.; Lee, Andrew; Li, Yupeng; Liu, Wei; Ronald Zhu, X.; Zhang, Xiaodong

2012-01-01

324

An innovative method of calculating target angle based on laser echo in laser imaging system  

NASA Astrophysics Data System (ADS)

Nowadays, lots of studies show the potential value of laser echo intensity in three-dimensional reconstruction of laser detection system. However, raw intensity information could not be used without correcting, since target geometry could also influence laser echo greatly. Target angle that is the angle between laser axis and target normal is important geometry information in intensity correcting. This paper studies the method to calculate target angle, which, as a result, could have great benefits in laser intensity correcting and further in three-dimensional reconstruction. The target angle could be calculated from the mathematical model between the target angle, distance and pulse width based on the laser space translation model presented. Simulation and experimental results show that, the method proposed can calculate the target angle effectively, which have great contribution in laser intensity correction and further in three-dimensional reconstruction.

Sun, He; Luo, Qiang; Yang, Yunyi; Cao, Jie; Hao, Qun

2013-12-01

325

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

326

THE VIEWING ANGLES OF BROAD ABSORPTION LINE VERSUS UNABSORBED QUASARS  

SciTech Connect

It was recently shown that there is a significant difference in the radio spectral index distributions of broad absorption line (BAL) quasars and unabsorbed quasars, with an overabundance of BAL quasars with steeper radio spectra. This result suggests that source orientation does play into the presence or absence of BAL features. In this paper, we provide more quantitative analysis of this result based on Monte Carlo simulations. While the relationship between viewing angle and spectral index does indeed contain a lot of scatter, the spectral index distributions are different enough to overcome that intrinsic variation. Utilizing two different models of the relationship between spectral index and viewing angle, the simulations indicate that the difference in spectral index distributions can be explained by allowing BAL quasar viewing angles to extend about 10 Degree-Sign farther from the radio jet axis than non-BAL sources, though both can be seen at small angles. These results show that orientation cannot be the only factor determining whether BAL features are present, but it does play a role.

DiPompeo, M. A.; Brotherton, M. S. [Department of Physics and Astronomy 3905, University of Wyoming, 1000 E. University, Laramie, WY 82071 (United States); De Breuck, C. [European Southern Observatory, Karl Schwarzschild Strasse 2, 85748 Garching bei Muenchen (Germany)

2012-06-10

327

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

328

Rubbing angle effect on in?plane switching liquid crystal displays  

Microsoft Academic Search

The rubbing angle effect on transmissive in?plane switching liquid crystal displays is analysed by the Jones matrix method. Simulation results show that the optimum rubbing angle is around 30°–40°; the cell gap\\/birefringence product (d?n) is about 0.33 µm. Increasing the rubbing angle can shorten the rise time and enlarge the grey scale voltage intervals. The optical characteristics are similar in two

2006-01-01

329

Multiband propagation experiment for narrowband characterisation of high elevation angle land mobile-satellite channels  

NASA Astrophysics Data System (ADS)

Results of a recent multiband propagation measurement campaign for the high elevation angle land mobile satellite channel are reported. Simultaneous narrowband sounding of the channel has been carried out in suburban, wooded and open areas of the UK using a helicopter-mounted platform to simulate the satellite signal at various elevation angles. Propagation related link degradations in the land mobile-satellite channel have been observed to be less severe when the path elevation angle is increased or radio frequency decreases.

Butt, G.; Evans, B. G.; Richharia, M.

1992-07-01

330

Fatigue of rubber-rubber joints and the effect of joint angle  

Microsoft Academic Search

Results of our investigation of the fatigue-to-failure of rubber-rubber joints are presented. Two different types of composites-type I with the angle tip of the stiffer matrix embedded in the softer matrix at an angle, and type II having the reverse configuration-were prepared for the study. The joint angle was varied from 30° to 180°, and it was observed that the

Amalendu Sarkar; Anil K. Bhowmick

1991-01-01

331

Impact angle control of interplanetary shock geoeffectiveness  

NASA Astrophysics Data System (ADS)

We use Open Geospace General Circulation Model global MHD simulations to study the nightside magnetospheric, magnetotail, and ionospheric responses to interplanetary (IP) fast forward shocks. Three cases are presented in this study: two inclined oblique shocks, hereafter IOS-1 and IOS-2, where the latter has a Mach number twice stronger than the former. Both shocks have impact angles of 30° in relation to the Sun-Earth line. Lastly, we choose a frontal perpendicular shock, FPS, whose shock normal is along the Sun-Earth line, with the same Mach number as IOS-1. We find that, in the IOS-1 case, due to the north-south asymmetry, the magnetotail is deflected southward, leading to a mild compression. The geomagnetic activity observed in the nightside ionosphere is then weak. On the other hand, in the head-on case, the FPS compresses the magnetotail from both sides symmetrically. This compression triggers a substorm allowing a larger amount of stored energy in the magnetotail to be released to the nightside ionosphere, resulting in stronger geomagnetic activity. By comparing IOS-2 and FPS, we find that, despite the IOS-2 having a larger Mach number, the FPS leads to a larger geomagnetic response in the nightside ionosphere. As a result, we conclude that IP shocks with similar upstream conditions, such as magnetic field, speed, density, and Mach number, can have different geoeffectiveness, depending on their shock normal orientation.

Oliveira, D. M.; Raeder, J.

2014-10-01

332

Orientation Angles of a Pulsar's Polarization Vector  

E-print Network

A statistical model of the polarization of pulsar radio emission is used to derive the general statistics of a polarization vector's orientation angles. The theoretical distributions are compared with orientation angle histograms computed from single-pulse, polarization observations of PSR B2020+28. The favorable agreement between the theoretical and measured distributions lends support to the underlying assumptions of the statistical model, and demonstrates, like recent work on other pulsars, that the handedness of circular polarization is associated with the radiation's orthogonally polarized modes. Comprehensive directional statistics of the vector's orientation angles are also derived, and are shown to follow the Watson bipolar and Fisher distributions in its limiting forms.

Mark M. McKinnon

2006-03-17

333

Bond Angles around a Tetravalent Central Atom  

NASA Astrophysics Data System (ADS)

There are several practical algorithms for building molecular geometries based on bond lengths, bond angles, and torsional angles. There seem to be few discussions of the effect changing one angle has on the remaining bond angles depending upon local symmetry. For example, in methane, CH4, the H-C-H bond angles are all tetrahedral, i.e., ? = 109.4712206... deg. If one considers CH3F, a molecule with C3v symmetry, how are the H-C-F bond angles related to the H-C-H bond angles? This study derives the bond angle relationships for a 4-bonded central atom such as a saturated C atom. For a 4-bonded central atom (6 bond angles) the possible local point group symmetries are Td(0), D2d(1), C3v(1), C2v(1), D2(2), C2(3), Cs(3), and C1(4). The numbers in parentheses are the degrees of freedom, i.e., the number of angles which can be assigned arbitrary values with the remaining angles fixed by symmetry. Analytical formulas relating the bond angles for each of the eight possible symmetries are derived. Also, formulas have been derived for the five possible symmetries of a planar 4-bonded atom, D4h(0), D2h(1), C2v(pendant, 1), C2v(trapezoid, 2), and Cs(3); the three possible structures of planar 3-bonded atoms, (D3h(0), C2v (1), and Cs(2); the three possible symmetries of pyramidal 3-bonded atoms, C3v(1), Cs(2), and C1 (3); and the trivial case of 2-bonded atoms, D{?h}(0) and C2v(bent 1). There are also six distinct 4-bonded central atom structures with all the bonds directed into a hemisphere, C4v(1), C2v(2), C2(3), Cs(trapezoid 3), Cs(pendant 3), and C1(4), geometries rarely seen in molecules.

Bohn, Robert Karl

2014-06-01

334

Reliability of Beta angle in assessing true anteroposterior apical base discrepancy in different growth patterns  

PubMed Central

Introduction: Beta angle as a skeletal anteroposterior dysplasia indicator is known to be useful in evaluating normodivergent growth patterns. Hence, we compared and verified the accuracy of Beta angle in predicting sagittal jaw discrepancy among subjects with hyperdivergent, hypodivergent and normodivergent growth patterns. Materials and Methods: Lateral cephalometric radiographs of 179 patients belonging to skeletal Classes I, II, and III were further divided into normodivergent, hyperdivergent, and hypodivergent groups based on their vertical growth patterns. Sagittal dysplasia indicators - angle ANB, Wits appraisal, and Beta angle values were measured and tabulated. The perpendicular point of intersection on line CB (Condylion-Point B) in Beta angle was designated as ‘X’ and linear dimension XB was evaluated. Results: Statistically significant increase was observed in the mean values of Beta angle and XB distance in the vertical growth pattern groups of both skeletal Class I and Class II patients thus pushing them toward Class III and Class I, respectively. Conclusions: Beta angle is a reliable indicator of sagittal dysplasia in normal and horizontal patterns of growth. However, vertical growth patterns significantly increased Beta angle values, thus affecting their reliability as a sagittal discrepancy assessment tool. Hence, Beta angle may not be a valid tool for assessment of sagittal jaw discrepancy in patients exhibiting vertical growth patterns with skeletal Class I and Class II malocclusions. Nevertheless, Class III malocclusions having the highest Beta angle values were unaffected. PMID:25810649

Sundareswaran, Shobha; Kumar, Vinay

2015-01-01

335

High Prevalence of Narrow Angles among Chinese-American Glaucoma and Glaucoma Suspect Patients  

PubMed Central

Purpose To evaluate the prevalence of gonioscopically narrow angles in a Chinese-American population with glaucoma or glaucoma suspicion. Patients and Methods Charts from all Chinese-American patients seen in a comprehensive ophthalmology clinic in the Chinatown district of San Francisco in 2002 were reviewed. One eye from each patient with glaucoma or glaucoma suspicion that met inclusion criteria was included (n=108). Data was collected for gender, age, race (self-declared), refraction (spherical equivalent), intraocular pressure (IOP), gonioscopy and vertical cup-to-disk ratio (CDR). Results Sixty percent (n=65) of Chinese-American eyes with glaucoma or glaucoma suspicion had gonioscopically narrow angles (Shaffer grade ?2 in three or more quadrants). Those with narrow angles were significantly older (P=0.004) than their open angle counterparts, but the two groups did not differ in terms of gender, refraction, IOP or CDR (all, P?0.071). In a multivariate model including age, gender and refraction as predictors of angle grade (open or narrow), only age was a significant predictor of angle grade (P=0.004). Conclusions A large proportion of Chinese-Americans in our study population with glaucoma or glaucoma suspicion had gonioscopically narrow angles. In multivariate analysis, patients with narrow angles were older than those with open angles but did not differ from them in terms of gender or refraction. Continued evaluation of angle closure glaucoma risk among Chinese-Americans is needed. PMID:19826385

Seider, Michael I; Pekmezci, Melike; Han, Ying; Sandhu, Simi; Kwok, Shiu Y; Lee, Roland Y; Lin, Shan C

2009-01-01

336

Contact Angles and Surface Tension of Germanium-Silicon Melts  

NASA Technical Reports Server (NTRS)

Precise knowledge of material parameters is more and more important for improving crystal growth processes. Two important parameters are the contact (wetting) angle and the surface tension, determining meniscus shapes and surface-tension driven flows in a variety of methods (Czochralski, EFG, floating-zone, detached Bridgman growth). The sessile drop technique allows the measurement of both parameters simultaneously and has been used to measure the contact angles and the surface tension of Ge(1-x)Si(x) (0 less than or equal to x less than or equal to 1.3) alloys on various substrate materials. Fused quartz, Sapphire, glassy carbon, graphite, SiC, carbon-based aerogel, pyrolytic boron nitride (pBN), AIN, Si3N4, and polycrystalline CVD diamond were used as substrate materials. In addition, the effect of different cleaning procedures and surface treatments on the wetting behavior were investigated. Measurements were performed both under dynamic vacuum and gas atmospheres (argon or forming gas), with temperatures up to 1100 C. In some experiments, the sample was processed for longer times, up to a week, to investigate any changes of the contact angle and/or surface tension due to slow reactions with the substrate. For pure Ge, stable contact angles were found for carbon-based substrates and for pBN, for Ge(1-x)Si(x) only for pBN. The highest wetting angles were found for pBN substrates with angles around 170deg. For the surface tension of Ge, the most reliable values resulted in gamma(T) = (591- 0.077 (T-T(sub m)) 10(exp -3)N/m. The temperature dependence of the surface tension showed similar values for Ge(1-x)Si(x), around -0.08 x 10(exp -3)N/m K, and a compositional dependence of 2.2 x 10(exp -3)N/m at%Si.

Croell, A.; Kaiser, N.; Cobb, S.; Szofran, F. R.; Volz, M.; Rose, M. Franklin (Technical Monitor)

2001-01-01

337

Effect of Load Phase Angle on Wind Turbine Blade Fatigue Damage: Preprint  

SciTech Connect

This paper examines the importance of phase angle variations with respect to fatigue damage. The operating loads on a generic conventional three-bladed upwind 1.5-MW wind turbine blade were analyzed over a range of operating conditions, and an aggregate probability distribution for the actual phase angles between the in-plane (lead-lag) and out-of-plane (flap) loads was determined. Using a finite element model of a generic blade and Miner's Rule, the accumulated theoretical damage (based on axial strains) resulting from a fatigue test with variable phase angles was compared to the damage resulting from a fatigue test with a constant phase angle. The nodal damage distribution at specific blade cross-sections are compared for the constant and variable phase angle cases. The sequence effects of various phase angle progressions were also considered. For this analysis, the finite element results were processed using the nonlinear Marco-Starkey damage accumulation model. Each phase angle sequence was constrained to have the same overall phase angle distribution and the same total number of cycles but the order in which the phase angles were applied was varied.

White, D. L.; Musial, W. D.

2003-11-01

338

A Distance and Angle Similarity Measure Method.  

ERIC Educational Resources Information Center

Discusses similarity measures that are used in information retrieval to improve precision and recall ratios and presents a combined vector-based distance and angle measure to make similarity measurement more scientific and accurate. Suggests directions for future research. (LRW)

Zhang, Jin; Korfhage, Robert R.

1999-01-01

339

Spherical Trigonometry of the Projected Baseline Angle  

E-print Network

The basic geometry of a stellar interferometer with two telescopes consists of a baseline vector and a direction to a star. Two derived vectors are the delay vector, and the projected baseline vector in the plane of the wavefronts of the stellar light. The manuscript deals with the trigonometry of projecting the baseline further outwards onto the celestial sphere. The position angle of the projected baseline is defined, measured in a plane tangential to the celestial sphere, tangent point at the position of the star. This angle represents two orthogonal directions on the sky, differential star positions which are aligned with or orthogonal to the gradient of the delay recorded in the u-v plane. The North Celestial Pole is chosen as the reference direction of the projected baseline angle, adapted to the common definition of the "parallactic" angle.

Mathar, R J

2006-01-01

340

Spherical Trigonometry of the Projected Baseline Angle  

E-print Network

The basic geometry of a stellar interferometer with two telescopes consists of a baseline vector and a direction to a star. Two derived vectors are the delay vector, and the projected baseline vector in the plane of the wavefronts of the stellar light. The manuscript deals with the trigonometry of projecting the baseline further outwards onto the celestial sphere. The position angle of the projected baseline is defined, measured in a plane tangential to the celestial sphere, tangent point at the position of the star. This angle represents two orthogonal directions on the sky, differential star positions which are aligned with or orthogonal to the gradient of the delay recorded in the u-v plane. The North Celestial Pole is chosen as the reference direction of the projected baseline angle, adapted to the common definition of the "parallactic" angle.

Richard J. Mathar

2009-05-02

341

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

342

Estimation of deviation angle for axial-flow compressor blade sections using inviscid-flow solutions  

NASA Technical Reports Server (NTRS)

Development of a method of estimating deviation angles by analytical procedures was begun. Solutions for inviscid, irrotational flow in the blade-to-blade plane were obtained with a finite-difference calculation method. Deviation angles for a plane cascade with a rounded trailing edge were estimated by using the inviscid-flow solutions and three trailing-edge hypotheses. The estimated deviation angles were compared with existing experimental data over a range of incidence angles at inlet flow angles of 30 deg and 60 deg. The results indicate that deviation angles can be estimated accurately (within 1 deg) by using one of the three trailing-edge hypotheses, but only when pressure losses are low. A new trailing-edge hypotheses is presented which is suitable (for the cascade considered) for both low- and high-loss operating points.

Miller, M. J.

1974-01-01

343

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, Toshimichi; Kunimori, Hiroo; Noda, Hirotomo; Hanada, Hideo; Araki, Hiroshi; Katayama, Masato

2011-08-01

344

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

345

Thermal conductivity in nanostructured materials and analysis of local angle between heat fluxes  

NASA Astrophysics Data System (ADS)

The phonon Boltzmann transport equation with the frequency-dependent model is solved numerically to study the thermal conductivity in nanoporous thin film and nanocomposite. Local angle between heat fluxes, defined as the angle between the directions of heat flux component qx and the local heat flux q, is introduced. At a fixed porosity or interface area, the thermal conductivity, local angle distribution, and the average angle of the two-dimensional nanoporous thin films with circular, hexagonal, square, and triangular pores are reported, and the thermal conductivity decreases with the increase in the interface area or porosity. Furthermore, the relationship between the thermal conductivity and average angle is also discussed for the three-dimensional nanoporous thin films with aligned or staggered pores, and silicon-germanium embedded and compacted nanocomposites. All the results show that the nanostructured material with a larger average angle between heat fluxes has a lower thermal conductivity.

Fu, B.; Tang, G. H.; Bi, C.

2014-09-01

346

Results and Lessons from MODIS Reflective Solar Bands Calibration: Pre-launch to On-orbit  

NASA Technical Reports Server (NTRS)

MODIS is a major instrument for the NASA EOS Terra (1aunched in December 1999) and Aqua (launched in May 2002) missions. It was designed and built to enhance and extend its heritage sensors' measurements and data records with applications covering a wide range of studies of the Earth's land, oceans, and atmosphere. MODIS has 36 spectral bands (0.41 - 14.4 micrometers) located on four focal plane assemblies (FPAs). It makes measurements at three nadir spatial resolutions: 250m (bands 1-2), 500m (bands 3-7), and lkm (bands 8-36). Because of instrument design complexity and stringent calibration requirements, extensive calibration and characterization activities were conducted pre-launch by the sensor vendor (Raytheon / Santa Barbara Remote Sensing) for both Tesa and Aqua MODIS. For the 20 reflective solar bands (RSB), these activities include measurements for the detectors noise characterization and radiometric performance, system level response versus scan-angle (RVS), polarization sensitivity, and relative spectral response (RSR). Key radiometric performance was evaluated using thermal vacuum observations. On-orbit MODIS RSB calibration is performed using a solar diffuser (SD) and solar diffuser stability monitor (SDSM) system. The SD bi-directional reflectance factor (BRF) was characterized pre-launch by the sensor vendor with reference samples traceable to NIST reflectance standards. This paper provides a summary of Terra and Aqua MODIS RSB pre-launch and on-orbit calibration and characterization activities and results with focus on the detectors' noise characterization and radiometric performance. Challenging and concerning issues and lessons learned from RSB pre-launch calibration and their impact on post launch performance are also presented. A similar summary for MODIS thermal emissive bands (TEB) is reported in a separate paper in these proceedings.

Xiong, X.; Che, N.; Barnes, W. L.; Guenther, B.

2006-01-01

347

Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching  

SciTech Connect

We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

2012-11-30

348

Droplet contact angle behavior on a hybrid surface with hydrophobic and hydrophilic properties  

NASA Astrophysics Data System (ADS)

A hybrid surface consisting of an array of hydrophobic and hydrophilic sites was designed and fabricated in an effort to better understand the effects of microscale surface features and chemistry on wettability. A model based on energy minimization was developed to design and predict the wettability of hybrid surfaces. Measured advancing, receding, and equilibrium contact angles fit the proposed model well. Experiments show that a higher degree of hydrophobicity results in higher contact angles and that contact angle hysteresis increases with decreasing micropillar spacing (b/a). Moreover, measured roll-off angle as an indicator of droplet shedding, decreases with b/a.

Yao, C. W.; Garvin, T. P.; Alvarado, J. L.; Jacobi, A. M.; Jones, B. G.; Marsh, C. P.

2012-09-01

349

Contact Angle Hysteresis on Superhydrophobic Stripes  

E-print Network

We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, $\\phi_S$. It is shown that the receding regime is determined by a longitudinal sliding motion the deformed contact line. Despite an anisotropy of the texture the receding contact angle remains isotropic, i.e. is practically the same in the longitudinal and transverse directions. The cosine of the receding angle grows nonlinearly with $\\phi_S$, in contrast to predictions of the Cassie equation. To interpret this we develop a simple theoretical model, which shows that the value of the receding angle depends both on weak defects at smooth solid areas and on the elastic energy of strong defects at the borders of stripes, which scales as $\\phi_S^2 \\ln \\phi_S$. The advancing contact angle was found to be anisotropic, except as in a dilute regime, and its value is determined by the rolling motion of the drop. The cosine of the longitudinal advancing angle depends linearly on $\\phi_S$, but a satisfactory fit to the data can only be provided if we generalize the Cassie equation to account for weak defects. The cosine of the transverse advancing angle is much smaller and is maximized at $\\phi_S\\simeq 0.5$. An explanation of its value can be obtained if we invoke an additional energy due to strong defects in this direction, which is shown to be proportional to $\\phi_S^2$. Finally, the contact angle hysteresis is found to be quite large and generally anisotropic, but it becomes isotropic when $\\phi_S\\leq 0.2$.

Alexander L. Dubov; Ahmed Mourran; Martin Möller; Olga I. Vinogradova

2014-07-21

350

Estimation of Surface Energies from Contact Angles  

Microsoft Academic Search

A RECENT communication by Gray1 illustrates a possible pitfall in the use of the theories of Fowkes2-5 and Good and Girifalco6,7 to estimate surface energies, and the various components of surface energy, from contact angles. This source of error is the incorrect identification of the surface tension terms, and the equating of the contact angle in a contaminated, experimental system

R. J. Good

1966-01-01

351

Classifying Triangles By Sides and Angles  

NSDL National Science Digital Library

You will learn to classify triangles by either their side lengths or their angle measures. There are two ways to classify triangles: by its sides, and by its angles. Let's see how to classify a triangle by its sides : A S calene Triangle has no congruent sides (no sides the same measure). An Isoceles Triangle has at least 2 congruent sides (2 sides of the same measure). ...

Mrs. Neubert

2010-10-05

352

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

353

Modelling PTB's spatial angle autocollimator calibrator  

NASA Astrophysics Data System (ADS)

The accurate and traceable form measurement of optical surfaces has been greatly advanced by a new generation of surface profilometers which are based on the reflection of light at the surface and the measurement of the reflection angle. For this application, high-resolution electronic autocollimators provide accurate and traceable angle metrology. In recent years, great progress has been made at the Physikalisch-Technische Bundesanstalt (PTB) in autocollimator calibration. For an advanced autocollimator characterisation, a novel calibration device has been built up at PTB: the Spatial Angle Autocollimator Calibrator (SAAC). The system makes use of an innovative Cartesian arrangement of three autocollimators (two reference autocollimators and the autocollimator to be calibrated), which allows a precise measurement of the angular orientation of a reflector cube. Each reference autocollimator is sensitive primarily to changes in one of the two relevant tilt angles, whereas the autocollimator to be calibrated is sensitive to both. The distance between the reflector cube and the autocollimator to be calibrated can be varied flexibly. In this contribution, we present the SAAC and aspects of the mathematical modelling of the system for deriving analytical expressions for the autocollimators' angle responses. These efforts will allow advancing the form measurement substantially with autocollimator-based profilometers and approaching fundamental measurement limits. Additionally, they will help manufacturers of autocollimators to improve their instruments and will provide improved angle measurement methods for precision engineering.

Kranz, Oliver; Geckeler, Ralf D.; Just, Andreas; Krause, Michael

2013-05-01

354

Angle Resolved Photoemission Studies of Silver -  

NASA Astrophysics Data System (ADS)

In this work, polarized synchrotron radiation is used to obtain both angle resolved photoemission data and angle integrated photoemission data on randomly oriented thick films of metallic silver, thin films of randomly oriented polycrystalline AgBr and AgBrI, and epitaxially grown AgBr on an Ag (111) single crystal. The experiments on the randomly oriented samples were concerned with obtaining the correct sample preparation methods--evaporation of AgBr or AgBrI onto Ag which was evaporated onto an Au plated glass disc; the correct temperature conditions--sample temperature must be kept below 140K, preferably close to 77K, in order to stop sample photolysis and decrease electron-phonon interactions. Asymmetry parameters as well as relative cross sections were determined for the valence bands of Ag and AgBr from 55eV through the Ag 4d Cooper minimum at 140eV. Comparison of asymmetry parameters with atomic data indicates that the valence bands derived from the Ag 4d levels in these systems are remarkably atomic-like. In AgBr, only the uppermost valence bands show a greatly reduced excursion of beta -value through the Cooper minimum. The total and partial valence band density of states (DOS and PDOS) for AgBr and AgBrI were experimentally obtained. The Ag 4d PDOS was nearly identical for both compounds. The halogen derived PDOS's differed in that the AgBrI halogen PDOS extended 0.2eV closer to the vacuum level than its AgBr counterpart. Experiments on AgBr epitaxially grown on Ag (111) single crystals demonstrated a definite surface core level shift (SCS) towards lower binding energy by 0.8eV for the Br 3d subshell. Unfortunately, these results do not conclusively state which ion terminates the surface. The general belief is that an AgBr (111) surface is bromide terminated. Preliminary band mapping experiments were performed on epitaxially grown AgBr on an AgBr (111) single crystal from Gamma to L in the first Brillouin zone which experimentally located the valence band maximum at L. Comparing the experimentally obtained band structure with speculative ones shows that the experimental ones are flatter than their speculative counterparts.

Kwawer, Gary Neil

355

Multi-angle Imaging SpectroRadiometer  

NASA Technical Reports Server (NTRS)

MISR views the sunlit Earth simultaneously at nine widely spaced angles and provides ongoing global coverage with high spatial detail. Its imagery is carefully calibrated to provide accurate measures of the brightness, contrast, and color of reflected sunlight. MISR provides new types of information for scientists studying Earth's climate, such as the regional and global distribution of different types of atmospheric particles and aerosols. The change in reflection at different view angles provides the means to distinguish aerosol types, cloud forms, and land surface cover. Combined with stereoscopic techniques, this enables construction of 3-D cloud models and estimation of the total amount of sunlight reflected by Earth's diverse environments. MISR was built for NASA by the Jet Propulsion Laboratory (JPL) in Pasadena, California. It is part of NASA's first Earth Observing System (EOS) spacecraft, the Terra spacecraft, which was launched into polar orbit from Vandenberg Air Force Base on December 18, 1999. MISR has been continuously providing data since February 24, 2000. [Mission Objectives] The MISR instrument acquires systematic multi-angle measurements for global monitoring of top-of-atmosphere and surface albedos and for measuring the shortwave radiative properties of aerosols, clouds, and surface scenes in order to characterize their impact on the Earth's climate. The Earth's climate is constantly changing -- as a consequence of both natural processes and human activities. Scientists care a great deal about even small changes in Earth's climate, since they can affect our comfort and well-being, and possibly our survival. A few years of below-average rainfall, an unusually cold winter, or a change in emissions from a coal-burning power plant, can influence the quality of life of people, plants, and animals in the region involved. The goal of NASA's Earth Observing System (EOS) is to increase our understanding of the climate changes that are occurring on our planet, and the reasons for these changes, so we are better equipped to anticipate and prepare for the future. The MISR instrument is a part of EOS. Its role is to measure the amount of sunlight scattered in different directions under natural conditions. These measurements will help quantify the amount of solar energy that heats the Earth's surface and atmosphere, and the changes that occur in them over the lifetime of the MISR instrument. From the MISR observations, we are also learning more about those components of the Earth's environment that scatter sunlight: particles in the atmosphere, the planet's surface, and clouds. MISR monitors changes in surface reflection properties, in atmospheric aerosol content and composition, and in cloudiness. Scientists use these data to study land use changes, air pollution, volcanic eruptions, as well as processes such as desertification, deforestation, and soil erosion. As part of the EOS program, computer models that predict future climate will be improved by the results of these studies. [Temporal_Coverage: Start_Date=2000-02-24; Stop_Date=] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180].

Diner, David J. (Principal Investigator)

356

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

357

A highly accurate dynamic contact angle algorithm for drops on inclined surface based on ellipse-fitting  

NASA Astrophysics Data System (ADS)

To improve the accuracy in the calculation of dynamic contact angle for drops on the inclined surface, a significant number of numerical drop profiles on the inclined surface with different inclination angles, drop volumes, and contact angles are generated based on the finite difference method, a least-squares ellipse-fitting algorithm is used to calculate the dynamic contact angle. The influences of the above three factors are systematically investigated. The results reveal that the dynamic contact angle errors, including the errors of the left and right contact angles, evaluated by the ellipse-fitting algorithm tend to increase with inclination angle/drop volume/contact angle. If the drop volume and the solid substrate are fixed, the errors of the left and right contact angles increase with inclination angle. After performing a tremendous amount of computation, the critical dimensionless drop volumes corresponding to the critical contact angle error are obtained. Based on the values of the critical volumes, a highly accurate dynamic contact angle algorithm is proposed and fully validated. Within nearly the whole hydrophobicity range, it can decrease the dynamic contact angle error in the inclined plane method to less than a certain value even for different types of liquids.

Xu, Z. N.; Wang, S. Y.

2015-02-01

358

On the formation of {l_angle}010{r_angle}-dislocations in the {gamma}{prime}-phase of superalloy single crystals during high temperature low stress creep  

SciTech Connect

The cutting of {gamma}{prime}-particles by dislocations during shear creep deformation of CMSX 6 superalloy single crystals loaded on the macroscopic crystallographic shear system {l_angle}110{r_angle}{l_brace}111{r_brace} at T = 1,025 C and {tau} = 85 MPa is analyzed using transmission electron microscopy (TEM). The formation of a {l_angle}010{r_angle}-dislocation in the {gamma}{prime}-phase was observed and investigated by means of stereo microscopy, line trace and g{center_dot}b-analysis. Two {gamma}-matrix channel dislocations with different Burgers vectors (b) of type a{sub 0}/2<110> jointly shear the {gamma}{prime}-particle where they form a superdislocation with a total Burgers vector of a{sub 0}{l_angle}010{r_angle}. The present paper provides microstructural evidence for this high temperature cutting process. The results are discussed in relation to the evolution of the dislocation structure in the {gamma}-channels during primary creep. Peach-Koehler forces were calculated to explain the formation of the {l_angle}010{r_angle}-dislocation.

Eggeler, G. [Ruhr-Univ. Bochum (Germany). Inst. fuer Werkstoffe-Werkstoffwissenschaft] [Ruhr-Univ. Bochum (Germany). Inst. fuer Werkstoffe-Werkstoffwissenschaft; Dlouhy, A. [Academy of Sciences, Brno (Czech Republic). Inst. of Physics and Materials] [Academy of Sciences, Brno (Czech Republic). Inst. of Physics and Materials

1997-10-01

359

KEY COMPARISON: Final report on CCL-K3: Calibration of angle standards  

NASA Astrophysics Data System (ADS)

This report is prepared by the Discussion Group 3 (DG3) for angle standards under the CCL Working Group on Dimensional Metrology (WGDM). It describes the results of Key Comparison CCL-K3 concerning measurements of a chrome carbide twelve-sided optical polygon with nominal angles of 30° and four angle blocks with nominal angles of 5 arc seconds, 5 minutes, 30 minutes and 5 degrees respectively. The majority of the thirteen participants (all from national metrology institutes) used a Moore or Heidenhain index table to position the test object (polygon/angle blocks) to the nominal angle. A few laboratories used other devices such as a ring laser or a measurement system designed in-house. To measure the deviation from the nominal angles, most laboratories used autocollimators, and only two laboratories used laser interferometers. The reported uncertainties for the polygon ranged from 8 msec to 100 msec (k = 1). For the angle blocks the uncertainties ranged from 11.5 msec to 735 msec (k = 1). The key comparison reference value (KCRV) for the polygon was determined using all 156 measurements reported by the thirteen participants. For the four angle blocks, a total of 51 angle measurements were reported. The KCRVs were calculated from only 47 measurement results due to the omission of four measurements that showed En values larger than one. The results of the polygon are consistent to a very high degree of accuracy. The angle blocks, with the exception of the four results that were omitted, were consistent although not to the same degree of accuracy as for the polygon. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Kruger, O. A.

2009-01-01

360

Transmembrane helix uniformity examined by spectral mapping of torsion angles.  

PubMed

The environment and unique balance of molecular forces within lipid bilayers has a profound impact upon the structure, dynamics, and function of membrane proteins. We describe the biophysical foundations for the remarkable uniformity of many transmembrane helices that result from the molecular interactions within lipid bilayers. In fact, the characteristic uniformity of transmembrane helices leads to unique spectroscopic opportunities allowing for phi,psi torsion angles to be mapped directly onto solid state nuclear magnetic resonance (NMR) PISEMA spectra. Results from spectral simulations, the solid state NMR-derived structure of the influenza A M2 proton channel transmembrane domain, and high-resolution crystal structures of 27 integral membrane proteins demonstrate that transmembrane helices tend to be more uniform than previously thought. The results are discussed through the definition of a preferred range of backbone varphi,psi torsion angles for transmembrane alpha helices and are presented with respect to improving biophysical characterizations of integral membrane proteins. PMID:18462683

Page, Richard C; Kim, Sanguk; Cross, Timothy A

2008-05-01

361

Acquisition and analysis of angle-beam wavefield data  

SciTech Connect

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. [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0250 (United States)

2014-02-18

362

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

363

Intermittent acute angle closure glaucoma and chronic angle closure following topiramate use with plateau iris configuration  

PubMed Central

This is a case report describing recurrent intermittent acute angle closure episodes in the setting of topiramate use in a female suffering from migraines. Despite laser peripheral iridotomy placement for the pupillary block component, and the discontinuation of topiramate, the acute angle closure did not resolve in the left eye with chronic angle closure and the patient required urgent trabeculectomy. The right eye responded to laser peripheral iridotomy immediately and further improved after the cessation of topiramate. While secondary angle closure glaucoma due to topiramate use has been widely reported, its effects in patients with underlying primary angle closure glaucoma have not been discussed. Our report highlights the importance of recognizing the often multifactorial etiology of angle closure glaucoma to help guide clinical management. PMID:25114497

Rajjoub, Lamise Z; Chadha, Nisha; Belyea, David A

2014-01-01

364

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. PMID:23633776

James, Johnson R.; Arun, K. V.; Talwar, Avaneendra; Kumar, T. S. S.

2013-01-01

365

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°. PMID:24743160

Seel, Thomas; Raisch, Jorg; Schauer, Thomas

2014-01-01

366

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

367

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

368

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. PMID:24751201

2014-01-01

369

On Navigation Systems for Motorcycles: The Influence and Estimation of Roll Angle  

NASA Astrophysics Data System (ADS)

Vehicle navigation systems use various sensors and the global positioning system (GPS) to locate a vehicle. This location is then matched to a map database to provide navigation information. Between GPS updates, the vehicle's heading angle and forward speed are used to “dead reckon” its position. Heading angle is often measured by integrating the output of a rate gyroscope. For this measurement to be equal to the vehicle's heading angle, the vehicle should not experience any rotation about its roll or pitch axes. For an automobile, the roll and pitch angles are small and may be neglected for the purposes of navigation. This article demonstrates that this same assumption is not true for a motorcycle. Through simulation, it is shown that for a motorcycle, obtaining a meaningful heading angle from a single angular rate measurement requires accounting for the motorcycle's roll angle. Methods to estimate roll angle and heading angle from available navigation measurements are presented, and two possible sensor configurations are compared. A motorcycle navigation scheme based on these roll angle estimation methods is shown to produce exceptional results in a simulation environment.

Coaplen, Joshua P.; Kessler, Patrick; O'Reilly, Oliver M.; Stevens, Dan M.; Hedrick, J. Karl

2005-09-01

370

Time-optimal rendezvous transfer trajectory for restricted cone-angle range solar sails  

NASA Astrophysics Data System (ADS)

The advantage of solar sails in deep space exploration is that no fuel consumption is required. The heliocentric distance is one factor influencing the solar radiation pressure force exerted on solar sails. In addition, the solar radiation pressure force is also related to the solar sail orientation with respect to the sunlight direction. For an ideal flat solar sail, the cone angle between the sail normal and the sunlight direction determines the magnitude and direction of solar radiation pressure force. In general, the cone angle can change from 0° to 90°. However, in practical applications, a large cone angle may reduce the efficiency of solar radiation pressure force and there is a strict requirement on the attitude control. Usually, the cone angle range is restricted less more than an acute angle (for example, not more than 40°) in engineering practice. In this paper, the time-optimal transfer trajectory is designed over a restricted range of the cone angle, and an indirect method is used to solve the two point boundary value problem associated to the optimal control problem. Relevant numerical examples are provided to compare with the case of an unrestricted case, and the effects of different maximum restricted cone angles are discussed. The results indicate that (1) for the condition of a restricted cone-angle range the transfer time is longer than that for the unrestricted case and (2) the optimal transfer time increases as the maximum restricted cone angle decreases.

He, Jing; Gong, Sheng-Ping; Jiang, Fang-Hua; Li, Jun-Feng

2014-10-01

371

Anterior Chamber Angle Shape Analysis and Classification of Glaucoma in SS-OCT Images  

PubMed Central

Optical coherence tomography is a high resolution, rapid, and noninvasive diagnostic tool for angle closure glaucoma. In this paper, we present a new strategy for the classification of the angle closure glaucoma using morphological shape analysis of the iridocorneal angle. The angle structure configuration is quantified by the following six features: (1) mean of the continuous measurement of the angle opening distance; (2) area of the trapezoidal profile of the iridocorneal angle centered at Schwalbe's line; (3) mean of the iris curvature from the extracted iris image; (4) complex shape descriptor, fractal dimension, to quantify the complexity, or changes of iridocorneal angle; (5) ellipticity moment shape descriptor; and (6) triangularity moment shape descriptor. Then, the fuzzy k nearest neighbor (fkNN) classifier is utilized for classification of angle closure glaucoma. Two hundred and sixty-four swept source optical coherence tomography (SS-OCT) images from 148 patients were analyzed in this study. From the experimental results, the fkNN reveals the best classification accuracy (99.11 ± 0.76%) and AUC (0.98 ± 0.012) with the combination of fractal dimension and biometric parameters. It showed that the proposed approach has promising potential to become a computer aided diagnostic tool for angle closure glaucoma (ACG) disease. PMID:25197561

Ni Ni, Soe; Tian, J.; Marziliano, Pina; Wong, Hong-Tym

2014-01-01

372

Neural network cloud screening algorithm, Part I: A synthetic case over land using micro-windows in O2 and CO2 near infrared absorption bands with nadir viewing  

NASA Astrophysics Data System (ADS)

A neural network is presented for estimating cloud water and ice paths, effective scattering heights of cloud water and ice, and column water vapor. The cloud water and ice are then used to classify scenes as either clear or cloudy using a simple threshold test of 2 gm-2 for water and 10 gm-2 for ice. Training of the neural networks was performed using high resolution spectra in micro-windows of O2 and CO2 near infrared absorption bands generated from an ensemble of analyzed meteorological fields from ECMWF and surface properties from MODIS. An independent test data set was generated using the same radiative transfermodel, but coupled with atmospheric profiles derived from CloudSat and Calipso data. Analysis indicates that the algorithmprovides approximately 75-90% accuracy with a 95-99% confidence level for classifying scenes as either cloudy or clear over land surfaces in nadir viewing geometry. These estimates are shown to be robust, in the sense that they are insensitive to realistic instrumental errors, errors in the meteorological analyses and surface properties, and errors in the simulations used for training.

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

2009-09-01

373

Flight test of the X-29A at high angle of attack: Flight dynamics and controls  

NASA Technical Reports Server (NTRS)

The NASA Dryden Flight Research Center has flight tested two X-29A aircraft at low and high angles of attack. The high-angle-of-attack tests evaluate the feasibility of integrated X-29A technologies. More specific objectives focus on evaluating the high-angle-of-attack flying qualities, defining multiaxis controllability limits, and determining the maximum pitch-pointing capability. A pilot-selectable gain system allows examination of tradeoffs in airplane stability and maneuverability. Basic fighter maneuvers provide qualitative evaluation. Bank angle captures permit qualitative data analysis. This paper discusses the design goals and approach for high-angle-of-attack control laws and provides results from the envelope expansion and handling qualities testing at intermediate angles of attack. Comparisons of the flight test results to the predictions are made where appropriate. The pitch rate command structure of the longitudinal control system is shown to be a valid design for high-angle-of-attack control laws. Flight test results show that wing rock amplitude was overpredicted and aileron and rudder effectiveness were underpredicted. Flight tests show the X-29A airplane to be a good aircraft up to 40 deg angle of attack.

Bauer, Jeffrey E.; Clarke, Robert; Burken, John J.

1995-01-01

374

Roll angle measurement based on common path compensation principle  

NASA Astrophysics Data System (ADS)

We propose a novel and compact roll angle displacement measurement method based on collimated laser position measurement and the common path compensation principle. The principles of the roll angle displacement measurement and the common path compensation are analyzed. The feasibility of the measurement method is verified, and the experimental results revealed a linear correlation coefficient of 0.99995 between the relative displacement of the measuring beam spot and the angular displacement. Furthermore, the theoretical measurement resolution is 0.013 arcsec. To test the performance of the compensation, a series of experiments, including one system stability experiment and two different environmental interference experiments, were performed. The experimental results indicated that the standard deviations of the measuring beam spot's angular drift were improved by 82.6-87.2%. Thus, the stability of the system and the measurement resolution were improved.

Zhu, Yiwei; Liu, Shaocong; Kuang, Cuifang; Li, Shuai; Liu, Xu

2015-04-01

375

Low back pain and lumbar angles in Turkish coal miners  

SciTech Connect

This study was designed to assess the incidence of low back pain among Turkish coal miners and to investigate the relationship between angles of the lumbar spine and low back pain in coal miners. Fifty underground workers (Group I) and 38 age-matched surface workers (Group II) were included in the study. All the subjects were asked about low back pain in the past 5 years. The prevalence of low back pain was higher in Group I than in Group II (78.0%, 32.4%, respectively, P {lt} 0.001). The results of the study showed that low back pain occurred in 78.0% of Turkish coal miners. Although the nature of the occupation may have influenced coal miners' lumbar spinal curvature, lumbar angles are not a determinant for low back pain in this population. Further extensive studies involving ergonomic measurements are needed to validate our results for Turkish coal mining industry.

Sarikaya, S.; Ozdolap, S.; Gumustas, S.; Koc, U. [Zonguldak Karaelmas University, Zonguldak (Turkey). Faculty of Medicine

2007-02-15

376

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. PMID:23635268

Liu, Yunlong; Flynn, Ryan T.; Yang, Wenjun; Kim, Yusung; Bhatia, Sudershan K.; Sun, Wenqing; Wu, Xiaodong

2013-01-01

377

Rapid emission angle selection for rotating-shield brachytherapy  

SciTech Connect

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 Axxent{sup TM} 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 Degree-Sign , 180 Degree-Sign , and 270 Degree-Sign . 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 D{sub 90} was maximized without violating the D{sub 2cc} 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 D{sub 90} to 85-100 Gy{sub 10}, 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 D{sub 90} 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 D{sub 90} 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 [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 (United States); Flynn, Ryan T.; Kim, Yusung; Bhatia, Sudershan K.; Sun, Wenqing [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Yang Wenjun [Department of Biomedical Engineering, University of Iowa, 1402 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242 (United States); Wu Xiaodong [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)

2013-05-15

378

High brightness angled cavity quantum cascade lasers  

NASA Astrophysics Data System (ADS)

A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 ?m, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 ?m. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm-2 sr-1 is obtained, which marks the brightest QCL to date.

Heydari, D.; Bai, Y.; Bandyopadhyay, N.; Slivken, S.; Razeghi, M.

2015-03-01

379

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

380

Effects of incidence angle on observations of equilibrium crater diameter  

NASA Astrophysics Data System (ADS)

Determining the equilibrium crater diameter for a crater population is important in lunar regolith depth estimates as the equilibrium diameter represents the steady-state between the formation of new craters and the removal of older craters [1]. [2] hypothesized that the number of craters identified in an image is dependent on the incidence angle and showed that for three different young mare regions, fewer craters are visible at lower incidence angles, affecting reliable estimates of the equilibrium diameter of the counted crater population. [3] disputed this hypothesis and the presence of an equilibrium crater population in the data from [2]. Testing the hypothesis from [2], we chose four Apollo Metric images of the same area with different incidence angles to examine the effects of resolution on apparent equilibrium diameter estimates. We selected a 100 km2 area centered at 27.3°N, 18.2°W in Mare Imbrium east of Lambert crater with data at 87°, 82°, 71°, and 50° incidence angles, and scan resolutions of 6.6 to 7.6 m/pixel. To compare the craters visible at different illuminations, we resampled the images to 10 m/pixel and employed three individuals to count craters. The cumulative histograms for the four Apollo Metric frames exhibit the effects of different incidence angles on reliably counting craters. Current results show that the crater counts for the 82° incidence angle image are the most consistent between different observers, finding a production function slope of -4.1 and an apparent equilibrium diameter of 200 m. Deviation from the small crater trends (equilibrium population?) and the production function slope observed at 82° incidence is found at the higher (87°) and lower (71°, 50°) incidence angles. We attribute some of this deviation to the effects of incidence angle on crater detection; at crater diameters >~300 m, we find similar production functions, an observation consistent with our identification of these large craters in all four illuminations. However, the small crater trends vary significantly among observations at different illuminations. An important question is whether the small crater slope and rollover we observe are representative of the equilibrium crater population or whether these observations are due to resolution limits of the images, a too-small count area, or shadow effects (e.g., loss of small craters in the shadows of larger craters). To test if the observed rollover in the cumulative histograms is due to resolution effects or to the observation of the equilibrium crater population, we will use substantially higher resolution images. Images from the Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (resolution increasing during the nominal mission from ~1.5 to ~0.5 m/pixel) at incidence angles ranging from 50° to 87°, focusing on higher incidences (70° to 87°), will be used to maximize the identification of small craters. [1] L. A. Soderblom (1970) JGR, 75, 2655. [2] B. B. Wilcox et al. (2005) Meteoritics & Plan. Sci., 40, 695. [3] V. R. Oberbeck (2008) Meteoritics & Plan. Sci., 43, 815.

Ostrach, L. R.; Denevi, B. W.; Hastings, A.; Koeber, S.; Robinson, M. S.; Thomas, P. C.; Tran, T. N.

2009-12-01

381

Angles of the CKM Unitarity Triangle Measured at Belle  

E-print Network

The Belle experiment has used several methods to measure or constrain the angles phi_1, phi_2, and phi_3 (or beta, alpha, and gamma) of the CKM unitarity triangle. The results are sin(2phi_1) = 0.728 \\pm 0.056 (stat) \\pm 0.023 (syst) or phi_1= (23.4 +2.7 -2.4) degrees from B0 -> J/psi K0 decays (140 fb-1); phi_2 = 0-19 degrees or 71-180 degrees at 95.4% CL from B0 -> pi+pi- decays (253 fb-1); and phi_3 = [68 +14 -15 (stat) \\pm 13 (syst) \\pm 11 (model)] degrees from B+ -> (D0, D0bar) K+, (D0,D0bar) -> K0_S pi+ pi- decays (253 fb-1). These values satisfy the triangle relation phi_1 + phi_2 + phi_3 = 180 degrees within their uncertainties. The angle phi_1 is also determined from several b -> s qbar q penguin-dominated decay modes; the value obtained by taking a weighted average of the individual results differs from the B0 -> J/psi K0 result by more than two standard deviations. The angle phi_2 is constrained by measuring a CP asymmetry in the decay time distribution; the asymmetry observed is large, and the difference in the yields of B0,B0bar -> pi+ pi- decays constitutes the first evidence for direct CP violation in the B system.

A. J. Schwartz

2005-08-15

382

Angle-resolved effective potentials for disk-shaped molecules  

E-print Network

We present an approach for calculating coarse-grained angle-resolved effective pair potentials for uniaxial molecules. For integrating out the intramolecular degrees of freedom we apply umbrella sampling and steered dynamics techniques in atomistically-resolved molecular dynamics (MD) computer simulations. Throughout this study we focus on disk-like molecules such as coronene. To develop the methods we focus on integrating out the van-der-Waals and intramolecular interactions, while electrostatic charge contributions are neglected. The resulting coarse-grained pair potential reveals a strong temperature and angle dependence. In the next step we fit the numerical data with various Gay-Berne-like potentials to be used in more efficient simulations on larger scales. The quality of the resulting coarse-grained results is evaluated by comparing their pair and many-body structure as well as some thermodynamic quantities self-consistently to the outcome of atomistic MD simulations of many particle systems. We find that angle-resolved potentials are essential not only to accurately describe crystal structures but also for fluid systems where simple isotropic potentials start to fail already for low to moderate packing fractions. Further, in describing these states it is crucial to take into account the pronounced temperature dependence arising in selected pair configurations due to bending fluctuations.

Thomas Heinemann; Karol Palczynski; Joachim Dzubiella; Sabine H. L. Klapp

2014-10-22

383

Angle-resolved effective potentials for disk-shaped molecules.  

PubMed

We present an approach for calculating coarse-grained angle-resolved effective pair potentials for uniaxial molecules. For integrating out the intramolecular degrees of freedom we apply umbrella sampling and steered dynamics techniques in atomistically-resolved molecular dynamics (MD) computer simulations. Throughout this study we focus on disk-like molecules such as coronene. To develop the methods we focus on integrating out the van der Waals and intramolecular interactions, while electrostatic charge contributions are neglected. The resulting coarse-grained pair potential reveals a strong temperature and angle dependence. In the next step we fit the numerical data with various Gay-Berne-like potentials to be used in more efficient simulations on larger scales. The quality of the resulting coarse-grained results is evaluated by comparing their pair and many-body structure as well as some thermodynamic quantities self-consistently to the outcome of atomistic MD simulations of many-particle systems. We find that angle-resolved potentials are essential not only to accurately describe crystal structures but also for fluid systems where simple isotropic potentials start to fail already for low to moderate packing fractions. Further, in describing these states it is crucial to take into account the pronounced temperature dependence arising in selected pair configurations due to bending fluctuations. PMID:25481132

Heinemann, Thomas; Palczynski, Karol; Dzubiella, Joachim; Klapp, Sabine H L

2014-12-01

384

Angle-resolved effective potentials for disk-shaped molecules  

NASA Astrophysics Data System (ADS)

We present an approach for calculating coarse-grained angle-resolved effective pair potentials for uniaxial molecules. For integrating out the intramolecular degrees of freedom we apply umbrella sampling and steered dynamics techniques in atomistically-resolved molecular dynamics (MD) computer simulations. Throughout this study we focus on disk-like molecules such as coronene. To develop the methods we focus on integrating out the van der Waals and intramolecular interactions, while electrostatic charge contributions are neglected. The resulting coarse-grained pair potential reveals a strong temperature and angle dependence. In the next step we fit the numerical data with various Gay-Berne-like potentials to be used in more efficient simulations on larger scales. The quality of the resulting coarse-grained results is evaluated by comparing their pair and many-body structure as well as some thermodynamic quantities self-consistently to the outcome of atomistic MD simulations of many-particle systems. We find that angle-resolved potentials are essential not only to accurately describe crystal structures but also for fluid systems where simple isotropic potentials start to fail already for low to moderate packing fractions. Further, in describing these states it is crucial to take into account the pronounced temperature dependence arising in selected pair configurations due to bending fluctuations.

Heinemann, Thomas; Palczynski, Karol; Dzubiella, Joachim; Klapp, Sabine H. L.

2014-12-01

385

4.MD,G Measuring Angles  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Draw an angle that measures 60 degrees like the one shown here: Draw another angle that measures 25 degrees. It should have the same vertex and share s...

2013-09-08

386

The Effects of Laser Reflection Angle on Radiometric Correction of the Airborne LIDAR Intensity Data  

NASA Astrophysics Data System (ADS)

Radiometric correction (RC) of the airborne Light Detection And Ranging (LiDAR) intensity data has been studied in the last few years. The physical model of the RC relies on the use of the laser range equation to convert the intensity values into the spectral reflectance of the reflected objects. A number of recent studies investigated the effects of the LiDAR system parameters (i.e. range, incidence angle, beam divergence, aperture size, automatic gain control, etc.) on the results of the RC process. Nevertheless, the condition of the object surface (slope and aspect) plays a crucial role in modelling the recorded intensity data. The variation of the object surface slope and aspect affects the direction as well as the magnitude of the reflected laser pulse which makes significant influence on the bidirectional reflectance distribution function. In this paper, the effects of the angle of reflection, which is the angle between the surface normal and the incidence laser pulse, on the RC results of the airborne LiDAR intensity data is investigated. A practical approach is proposed to compute the angle of reflection using the digital surface model (DSM) derived from the LiDAR data. Then, a comparison between the results of the intensity data after RC using the scan angle and RC using the angle of reflection is carried out. The comparison is done by converting the intensity data into equivalent image data and evaluating the classification results of the intensity image data. Preliminary findings show that: 1) the variance-to-mean ratio of the land cover features are significantly reduced while using the angle of reflection in the RC process; 2) 4% of accuracy improvement can be achieved using the intensity data corrected with the scan angle. The accuracy improvement increases to 8% when using the intensity data corrected with the angle of reflection. The research work practically justifies the use of the reflection angle in the RC process of airborne LiDAR intensity data.

Shaker, A.; Yan, W. Y.; El-Ashmawy, N.

2011-09-01

387

Joint angles and angular velocities and relevance of eigenvectors during prehension in the monkey.  

PubMed

Hand shaping during prehension involves intricate coordination of a complex system of bones, joints, and muscles. It is widely hypothesized that the motor system uses strategies to reduce the degrees of independent control. Both biomechanical constraints that result in coupling of the fingers and joints and neural synergies act to simplify the control problem. Synergies in hand shaping are typically defined using principal component-like analyses to define orthogonal patterns of movement. Although much less examined, joint angle velocities are also important parameters governing prehension. The primary goal of this study was to evaluate joint angles and joint angle velocities during prehension in monkeys. Fourteen joint angles and angular velocities were measured as monkeys reached to and grasped a set of objects designed to systematically vary hand shapes. Hand shaping patterns in joint angles and velocities were examined using singular value decomposition (SVD). Highly correlated patterns of movements were observed in both joint angles and joint angle velocities, but there was little correlation between the two, suggesting that velocities are controlled separately. Joint angles and velocities can be defined by a small number of eigenvectors by SVD. The unresolved question of the functional relevance of higher-order eigenvectors was also evaluated. Results support that higher-order components are not easily distinguished from noise and are likely not of physiological significance. PMID:25326080

Prosise, Jodi F; Hendrix, Claudia M; Ebner, Timothy J

2015-02-01

388

What's my angle? : do people with big hands have larger angles between their fingers?  

NSDL National Science Digital Library

This activity challenges students to think about angles as geometric shapes and to find the sizes of the angles between their fingers. It is part of the Figure This! collection of 80 online mathematical challenges emphasizing real world uses of mathematics. For this challenge, the students trace a hand stretched to form an L-shape with the thumb and sketches angles of 90 degrees and 45 degrees between the thumb and index finger. They use the sketches to estimate the angles between their other fingers. Questions extend the challenge to finding the distance a bike wheel travels in one rotation, the headings of compass directions, and the number of degrees between the hands of a clock. Also included are directions for making a protractor by folding a circle of paper and a question about the meaning of negative angles. Copyright 2005 Eisenhower National Clearinghouse

National Action Council for Minorities in Engineering

2002-01-01

389

Optimization of Wind Farm Performance Based on Yaw Angle Control  

NASA Astrophysics Data System (ADS)

Inside wind farms, the wakes of upwind turbines result in a significant reduction in power production. Yawing upwind turbines can be used to deflect the wakes away from turbines. Even though this reduces the power production of upwind turbines, it can potentially result in increasing the power production of the whole wind farm. The present work aims to investigate the possibility of improving the performance of wind farms by controlling the yaw angle of turbines. In this regard, wind-tunnel experiments were carried out to study the wake interactions of model turbines and their performance at different yaw angles and different layout configurations. First, it is observed that the power production of the two model turbines, located in a line parallel to the wind, is not considerably improved by yawing the first one. Next, the effect of yaw angle on the performance of a row of ten model turbines parallel to the wind flow, leading to full-wake conditions, was studied. Two configurations were considered: (a) turbines are yawed to the same direction with respect to the wind flow, and (b) each two consecutive turbines are yawed to different directions. The first configuration is found to have a better performance in terms of power production, whereas fatigue loads are lower in the second one. In the first configuration, the best power production is observed when the first turbine has a large yaw angle, and it progressively decreases for the next turbines. Yaw angle control was also considered for the case that turbines are located in partial-wake conditions. These conditions, which commonly occur in real-scale wind farms, are achieved in the wind tunnel by shifting the downwind turbines laterally with respect to the first turbine. In this case, not only can yawing upwind turbines potentially increase the power production of wind farms, but also it can decrease the fatigue loads on downwind turbines by totally deflecting the wake away from them. In general, it is found that the control of the yaw angle in this situation can significantly improve the power even for just two turbines, unlike the case in which the wind flow is exactly parallel to the row of turbines.

Bastankhah, Majid; Porté-Agel, Fernando; Dios Romero, Isabel

2014-05-01

390

Decoding low dihedral angles in gabbroic layered intrusions  

NASA Astrophysics Data System (ADS)

Texturally equilibrated rocks are granular with a unimodal grain size, smoothly curved grain boundaries, and angles at three-grain junctions of 110-140°. Gabbros are not texturally equilibrated: primocrysts commonly have planar faces whereas later-formed phases fill in the interstitial spaces. Augite-plagioclase-plagioclase dihedral angles (?cpp) rarely attain the equilibrium value in gabbros and the population of disequilibrium angles preserves otherwise inaccessible information about rock history. The ?cpp population varies significantly between different basaltic bodies. In a rapidly cooled dolerite ?cpp has a low median (60-70°) and a high standard deviation (20-25°). The plagioclase-augite grain boundaries are generally planar. In more slowly cooled gabbros in layered intrusions, the angle populations have a higher median (80-110°) with a low standard deviation (10-15°). The plagioclase-augite grain boundaries are generally planar far from the triple junction, but curve within 10 microns of the junction. This curvature is commonly asymmetric. The angle population in solidified gabbros infiltrated by low-temperature melts is similar to that in dolerites, although the low angles are associated with cuspate interstitial grains. The dihedral angle is a function of both the original solidification process and subsequent high-temperature (melt-absent) grain boundary migration. Infilling of a melt pocket by overgrowth of the bounding solid phases necessitates supersaturation, and this is easier to attain for planar faces, resulting in inhibition of augite growth into pores bounded by planar plagioclase grains and an asymmetry of the initial augite-plag-plag junction. If the solidified gabbro is kept sufficiently hot these initial junction geometries can change during textural equilibration. In the Skaergaard, Rum and Bushveld intrusions, the median ?cpp varies with liquidus assemblage, increasing step-wise on the addition of a new liquidus phase. Locally, these steps are offset relative to the arrival of the new phase, inconsistent with a compositional control. It is more likely that the control is due to step-wise changes in the fractional latent heat. During solidification the temperature of the liquid-bearing parts of a fractionating intrusion is partially buffered by crystallisation. An increase in the fractional latent heat associated with a new liquidus phase decreases the rate at which the magma temperature drops. Although the step-wise changes in ?cpp may be a result of changes in the extent of sub-solidus textural equilibration, it is also possible that the different angle populations are an original feature formed during solidification, via a control by cooling rate on the supersaturation required to overgrow the pore walls. The dihedral angle, combined with other textural features such as grain boundary curvature, is a useful indicator of magma chamber processes. It can be used to detect changes in liquidus assemblage in fractionating gabbros when more conventional indicators (e.g. grain shape or modal assemblage) don’t provide conclusive answers, and to constrain the spatial extent of late-stage infiltration when traditional chemical traces are absent.

Holness, M. B.; Humphreys, M.; Veksler, I. V.

2010-12-01

391

Characterizing the combinatorial beam angle selection problem  

NASA Astrophysics Data System (ADS)

The beam angle selection (BAS) problem in intensity-modulated radiation therapy is often interpreted as a combinatorial optimization problem, i.e. finding the best combination of ? beams in a discrete set of candidate beams. It is well established that the combinatorial BAS problem may be solved efficiently with metaheuristics such as simulated annealing or genetic algorithms. However, the underlying parameters of the optimization process, such as the inclusion of non-coplanar candidate beams, the angular resolution in the space of candidate beams, and the number of evaluated beam ensembles as well as the relative performance of different metaheuristics have not yet been systematically investigated. We study these open questions in a meta-analysis of four strategies for combinatorial optimization in order to provide a reference for future research related to the BAS problem in intensity-modulated radiation therapy treatment planning. We introduce a high-performance inverse planning engine for BAS. It performs a full fluence optimization for ?3600 treatment plans per hour while handling up to 50?GB of dose influence data (?1400 candidate beams). For three head and neck patients, we compare the relative performance of a genetic, a cross-entropy, a simulated annealing and a naive iterative algorithm. The selection of ensembles with 5, 7, 9 and 11 beams considering either only coplanar or all feasible candidate beams is studied for an angular resolution of 5°, 10°, 15° and 20° in the space of candidate beams. The impact of different convergence criteria is investigated in comparison to a fixed termination after the evaluation of 10?000 beam ensembles. In total, our simulations comprise a full fluence optimization for about 3000?000 treatment plans. All four combinatorial BAS strategies yield significant improvements of the objective function value and of the corresponding dose distributions compared to standard beam configurations with equi-spaced coplanar beams. The genetic and the cross-entropy algorithms showed faster convergence in the very beginning of the optimization but the simulated annealing algorithm eventually arrived at almost the same objective function values. These three strategies typically yield clinically equivalent treatment plans. The iterative algorithm showed the worst convergence properties. The choice of the termination criterion had a stronger influence on the performance of the simulated annealing algorithm than on the performance of the genetic and the cross-entropy algorithms. We advocate to terminate the optimization process after the evaluation of 1000 beam combinations without objective function decrease. For our simulations, this resulted in an average deviation of the objective function from the reference value after 10?000 evaluated beam ensembles of 0.5% for all metaheuristics. On average, there was only a minor improvement when increasing the angular resolution in the space of candidate beam angles from 20° to 5°. However, we observed significant improvements when considering non-coplanar candidate beams for challenging head and neck cases.

Bangert, Mark; Ziegenhein, Peter; Oelfke, Uwe

2012-10-01

392

Sunspot group tilt angles and the strength of the solar cycle  

NASA Astrophysics Data System (ADS)

Context. It is well known that the tilt angles of active regions increase with their latitude (Joy's law). It has never been checked before, however, whether the average tilt angles change from one cycle to the next. Flux transport models show the importance of tilt angles for the reversal and build up of magnetic flux at the poles, which is in turn correlated to the strength of the next cycle. Aims: Here we analyse time series of tilt angle measurements and look for a possible relationship of the tilt angles with other solar cycle parameters, in order to glean information on the solar dynamo and to estimate their potential for predicting solar activity. Methods: We employed tilt angle data from Mount Wilson and Kodaikanal observatories covering solar cycles 15 to 21. We analyse the latitudinal distribution of the tilt angles (Joy's law), their variation from cycle to cycle, and their relationship to other solar cycle parameters, such as the strength (or total area covered by sunspots in a cycle), amplitude, and length. Results: The two main results of our analysis follow. 1. We find an anti-correlation between the mean normalised tilt angle of a given cycle and the strength (or amplitude) of that cycle, with a correlation coefficient of rc = -0.95 (99.9% confidence level) and rc = -0.93 (99.76% confidence level) for Mount Wilson and Kodaikanal data, respectively. 2. The product of the cycle's averaged tilt angle and the strength of the same cycle displays a significant correlation with the strength of the next cycle (rc = 0.65 at 89% confidence level and rc = 0.70 at 92% confidence level for Mount Wilson and Kodaikanal data, respectively). An even better correlation is obtained between the source term of the poloidal flux in Babcock-Leighton-type dynamos (which contains the tilt angle) and the amplitude of the next cycle. Further we confirm the linear relationship (Joy's law) between the tilt angle and latitude with slopes of 0.26 and 0.28 for Mount Wilson and Kodaikanal data, respectively. In addition, we obtain good positive correlations between the normalised-area-weighted tilt angle and the length of the following cycle, whereas the strength or the amplitude of the next cycle does not appear to be correlated to the tilt angles of the current cycle alone. Conclusions: The results of this study indicate that, in combination with the cycle strength, the active region tilt angles play an important role in building up the polar fields at cycle minimum.

Dasi-Espuig, M.; Solanki, S. K.; Krivova, N. A.; Cameron, R.; Peñuela, T.

2010-07-01

393

Incidence angle normalization of radar backscatter data  

Technology Transfer Automated Retrieval System (TEKTRAN)

NASA’s Soil Moisture Passive Active (SMAP) satellite (~2014) will include a radar system that will provide L-band multi-polarization backscatter at a constant incidence angle of 40º. During the pre-launch phase of the project there is a need for observations that will support the radar-based soil mo...

394

1. INTRODUCTION Angle-Independent Doppler  

E-print Network

= -R(') / cos o.(1 In applications such as police radars or muzzle veloc- ity radars, a priori the target heading and the range vector is not known a priori, a Doppler velocity radar must estimate them knowledge of 0 is obtained by preset- ting a narrow beam radar at a predetermined angle relative to a known

Levanon, Nadav

395

Determining surface wave arrival angle anomalies  

Microsoft Academic Search

A new method for measuring arrival angles of teleseismic Love and Rayleigh waves is developed. The new method utilizes estimates of surface wave dispersion to create a phase-matched filter to isolate the Love or Rayleigh wave in three-component recordings. The polarization of the filtered wave group is determined in the time domain by application of a variation of the complex

Erik W. F. Larson; Göran Ekström

2002-01-01

396

Limited View Angle Iterative CT Reconstruction  

E-print Network

Detection Inc., Newark, CA, USA 3Astrophysics Inc., City of Industry, CA, USA #12;Introduction: Security vs-views and limited-angle data in divergent-beam CT by E. Y. Sidky, CM Kao, and X. Pan (2006) Few-View Projection

397

Looking at Faces from a New Angle.  

ERIC Educational Resources Information Center

Describes a fifth grade art activity inspired by a restaurant logo that consisted of angled faces fragmented down the middle, with geometric profiles, in bold colors. Explains the process of creating the abstract split faces, from the initial drawing to adding colors. (CMK)

Mulkey, Mary McNamara; Malm, Susanne

2000-01-01

398

Partitioning Pythagorean Triangles Using Pythagorean Angles  

ERIC Educational Resources Information Center

Inside any Pythagorean right triangle, it is possible to find a point M so that drawing segments from M to each vertex of the triangle yields angles whose sines and cosines are all rational. This article describes an algorithm that generates an infinite number of such points.

Swenson, Carl E.; Yandl, Andre L.

2012-01-01

399

Sensor Tracks the Sun From Any Angle  

NASA Technical Reports Server (NTRS)

Sensor system locates Sun from any angle and generates error signals to point object toward Sun and follow its motion. Sun-sensor system includes three photodetectors, each with separate field of view defined by set of apertures. As equipment rotates about axis, detectors put out time-varying signals processed by external electronics to determine rotation rate and direction to Sun.

Birnbaum, M., M.; Bunker, R. L.

1986-01-01

400

Instrument accurately measures weld angle and offset  

NASA Technical Reports Server (NTRS)

Weld angle is measured to the nearest arc minute and offset to one thousandth of an inch by an instrument designed to use a reference plane at two locations on a test coupon. A special table for computation has been prepared for use with the instrument.

Boyd, W. G.

1967-01-01

401

primary open angle glaucoma and exfoliation syndrome  

E-print Network

Purpose: To assess whether lysyl oxidase-like 1 (LOXL1) polymorphisms are associated with primary open-angle glaucoma (POAG) and exfoliation syndrome (XFS). Methods: Japanese patients with POAG (n=213) or XFS (n=89) and 191 control subjects were analyzed for LOXL1 polymorphisms (rs1048661: 758G

Fumihiko Mabuchi; Yoichi Sakurada; Kenji Kashiwagi; Zentaro Yamagata; Hiroyuki Iijima

402

Prevalence of Open-Angle Glaucoma and  

E-print Network

Objective: To estimate age- and gender-specific prevalences of ocular hypertension and open-angle glaucoma (OAG) in adult Latinos. Design: Population-based, cross-sectional study. Participants: Six thousand three hundred fifty-seven Latinos 40 years and older from 6 census tracts in Los Angeles

Ocular Hypertension In Latinos; The Los; Angeles Latino; Eye Study; Jennifer Deneen; M. Roy Wilson; Stanley P. Azen; Los Angeles Latino

403

Points, Lines, and Angles, Oh My!  

NSDL National Science Digital Library

In this lesson, students work to identify points, lines, line segments, rays, angles and perpendicular and parallel lines. Students create webs of yarn and analyze the web for geometric properties listed above. Students also work with pattern blocks to gain experience.

victoria pease

2012-08-02

404

Flare angles measured with ball gage  

NASA Technical Reports Server (NTRS)

Precision tungsten carbide balls measure the internal angle of flared joints. Measurements from small and large balls in the flare throat to an external reference point are made. The difference in distances and diameters determine the average slope of the flare between the points of ball contact.

Cleghorn, D.; Wall, W. A.

1968-01-01

405

High resolution maps from wide angle sonar  

Microsoft Academic Search

We describe the use of multiple wide-angle sonar range measurements to map the surroundings of an autonomous mobile robot. A sonar range reading provides information concerning empty and occupied volumes in a cone (subtending 30 degrees in our case) in front of the sensor. The reading is modelled as probability profiles projected onto a rasterized map, where somewhere occupied and

H. Moravec; A. Elfes

1985-01-01

406

Contact Angle Changes Induced by Immunocomplex Formation†  

PubMed Central

Immunoassays analyzing interactions between antigens and antibodies can be affected by capillary action together with binding affinity. This paper studies contact-angle changes of bacterial suspensions on antibody immobilized surfaces. The capillary action and the dried pattern of the cell suspensions are analyzed and correlated with specific- and nonspecific bindings between bacteria and antibodies. PMID:24482797

Kim, Jong-Hoon; Shen, Amy Q.; Lee, Kyong-Hoon; Cangelosi, Gerard A.; Chung, Jae-Hyun

2014-01-01

407

Scaled high angle research vehicle SHARV) program  

Microsoft Academic Search

A flight test research program employing a remotely piloted vehicle (RPV) within high angle of attack range has commenced at the Faculty of Power and Aeronautical Engineering of Warsaw University of Technology, Poland. The initial flights of the scaled model of the “Bielik” aircraft were made with the aim to correlate RPV and full?scale flight stall and departure and spin

M. Szender

2004-01-01

408

Source-specular-reflector-sensor solid angles  

NASA Technical Reports Server (NTRS)

A formula is derived that describes the size of the solid angle within which must be the normal to a flat specular reflector, if such a reflector is to redirect light from a small but finite extended source to a small but finite extended detector. The formula assumes the rules of geometrical optics and does not account for the effects of diffraction.

Vanderbilt, V. C.

1987-01-01

409

LUBRICATION APPROXIMATION WITH PRESCRIBED NONZERO CONTACT ANGLE  

E-print Network

LUBRICATION APPROXIMATION WITH PRESCRIBED NONZERO CONTACT ANGLE Felix Otto Department--time existence for a weak solution s(t; x) â?? 0 of the lubrication approximation @ t s + @ x (s @ 3 x s) = 0 in fs will later motivate the way we construct approximate solutions for the lubrication approximation we are going

Otto, Felix

410

Factors controlling hole angle and direction  

SciTech Connect

An understanding of the factors controlling hole angle and direction will contribute to hitting the drilling target more frequently. As the bottomhole assembly (BHA) behavior and the bit/formation interactions become better understood, less expensive and safer holes can be drilled.

Walker, B.H.

1986-11-01

411

Polarization azimuth angle in daylight scenes  

Microsoft Academic Search

Lord Rayleigh derived the degree of polarization for singular molecular scattering phenomena in the atmosphere as a function of the relative angular orientations of the source, scattering center, and observer. This paper extends the Rayleigh model by giving the azimuth angle for the linearly polarized scattered radiation detected by the observer. Together these two parameters give a complete Stokes vector

Roy M. Matchko; Grant R. Gerhart

2005-01-01

412

XFEL OSCILLATOR SIMULATION INCLUDING ANGLE-DEPENDENT CRYSTAL REFLECTIVITY  

SciTech Connect

The oscillator package within the GINGER FEL simulation code has now been extended to include angle-dependent reflectivity properties of Bragg crystals. Previously, the package was modified to include frequencydependent reflectivity in order to model x-ray FEL oscillators from start-up from shot noise through to saturation. We present a summary of the algorithms used for modeling the crystal reflectivity and radiation propagation outside the undulator, discussing various numerical issues relevant to the domain of high Fresnel number and efficient Hankel transforms. We give some sample XFEL-O simulation results obtained with the angle-dependent reflectivity model, with particular attention directed to the longitudinal and transverse coherence of the radiation output.

Fawley, William; Lindberg, Ryan; Kim, K-J; Shvyd'ko, Yuri

2010-08-23

413

The Turbulent Flow in Diffusers of Small Divergence Angle  

NASA Technical Reports Server (NTRS)

The turbulent flow in a conical diffuser represents the type of turbulent boundary layer with positive longitudinal pressure gradient. In contrast to the boundary layer problem, however, it is not necessary that the pressure distribution along the limits of the boundary layer(along the axis of the diffuser) be given, since this distribution can be obtained from the computation. This circumstance, together with the greater simplicity of the problem as a whole, provides a useful basis for the study of the extension of the results of semiempirical theories to the case of motion with a positive pressure gradient. In the first part of the paper,formulas are derived for the computation of the velocity and.pressure distributions in the turbulent flow along, and at right angles to, the axis of a diffuser of small cone angle. The problem is solved.

Gourzhienko, G. A.

1947-01-01

414

Detection Angle Calibration of Pressure-Sensitive Paints  

NASA Technical Reports Server (NTRS)

Uses of the pressure-sensitive paint (PSP) techniques in areas other than external aerodynamics continue to expand. The NASA Glenn Research Center has become a leader in the application of the global technique to non-conventional aeropropulsion applications including turbomachinery testing. The use of the global PSP technique in turbomachinery applications often requires detection of the luminescent paint in confined areas. With the limited viewing usually available, highly oblique illumination and detection angles are common in the confined areas in these applications. This paper will describe the results of pressure, viewing and excitation angle dependence calibrations using three popular PSP formulations to get a better understanding of the errors associated with these non-traditional views.

Bencic, Timothy J.

2000-01-01

415

Compact multilayer film structure for angle insensitive color filtering.  

PubMed

Here we report a compact multilayer film structure for angle robust color filtering, which is verified by theoretical calculations and experiment results. The introduction of the amorphous silicon in the proposed unsymmetrical resonant cavity greatly reduces the angular sensitivity of the filters, which is confirmed by the analysis of the phase shift within the structure. The temperature of the substrate during the deposition is expressly investigated to obtain the best optical performance with high peak reflectance and good angle insensitive color filtering by compromising the refractive index of dielectric layer and the surface roughness of the multilayer film. And the outlayer of the structure, worked as the anti-reflection layer, have an enormous impact on the filtering performance. This method, described in this paper, can have enormous potential for diverse applications in display, colorful decoration, anti-counterfeiting and so forth. PMID:25788330

Yang, Chenying; Shen, Weidong; Zhang, Yueguang; Li, Kan; Fang, Xu; Zhang, Xing; Liu, Xu

2015-01-01

416

Lorentz Angle Measurement for CO2/Isobutane Gas Mixtures  

E-print Network

We have developed a Lorentz angle measurement system for cool gas mixtures in the course of our R&D for a proposed JLC central drift chamber (JLC-CDC). The measurement system is characterized by the use of two laser beams to produce primary electrons and flash ADCs to read their signals simultaneously. With this new system, we have measured Lorentz angles for CO2/isobutane gas mixtures with different proportions (95:5, 90:10, and 85:15), varying drift field from 0.6 to 2.0 kV/cm and magnetic field up to 1.5 T. The results of the measurement are in good agreement with GARFIELD/MAGBOLTZ simulations.

Hoshina, K; Khalatyan, N S; Nitoh, O; Okuno, H; Kato, Y; Kobayashi, M; Kurihara, Y; Kuroiwa, H; Nakamura, Y; Sakieda, K; Suzuki, Y; Watanabe, T

2002-01-01

417

Interference-induced angle-independent acoustical transparency  

NASA Astrophysics Data System (ADS)

It is revealed that the Fano-like interference leads to the extraordinary acoustic transmission through a slab metamaterial of thickness much smaller than the wavelength, with each unit cell consisting of a Helmholtz resonator and a narrow subwavelength slit. More importantly, both the theoretical analysis and experimental measurement show that the angle-independent acoustical transparency can be realized by grafting a Helmholtz resonator and a quarter-wave resonator to the wall of a narrow subwavelength slit in each unit cell of a slit array. The observed phenomenon results from the interferences between the waves propagating in the slit, those re-radiated by the Helmholtz resonator, and those re-radiated by the quarter-wave resonator. The proposed design may find its applications in designing angle-independent acoustical filters and controlling the phase of the transmitted waves.

Qi, Lehua; Yu, Gaokun; Wang, Xinlong; Wang, Guibo; Wang, Ning

2014-12-01

418

View Angle Effects on MODIS Snow Mapping in Forests  

NASA Technical Reports Server (NTRS)

Binary snow maps and fractional snow cover data are provided routinely from MODIS (Moderate Resolution Imaging Spectroradiometer). This paper investigates how the wide observation angles of MODIS influence the current snow mapping algorithm in forested areas. Theoretical modeling results indicate that large view zenith angles (VZA) can lead to underestimation of fractional snow cover (FSC) by reducing the amount of the ground surface that is viewable through forest canopies, and by increasing uncertainties during the gridding of MODIS data. At the end of the MODIS scan line, the total modeled error can be as much as 50% for FSC. Empirical analysis of MODIS/Terra snow products in four forest sites shows high fluctuation in FSC estimates on consecutive days. In addition, the normalized difference snow index (NDSI) values, which are the primary input to the MODIS snow mapping algorithms, decrease as VZA increases at the site level. At the pixel level, NDSI values have higher variances, and are correlated with the normalized difference vegetation index (NDVI) in snow covered forests. These findings are consistent with our modeled results, and imply that consideration of view angle effects could improve MODIS snow monitoring in forested areas.

Xin, Qinchuan; Woodcock, Curtis E.; Liu, Jicheng; Tan, Bin; Melloh, Rae A.; Davis, Robert E.

2012-01-01

419

Wide-angle breast tomosynthesis: initial comparative evaluation  

NASA Astrophysics Data System (ADS)

Conventional mammography is largely limited by superimposed anatomy which is alleviated by breast tomosynthesis and CT. Limited acquisition in tomosynthesis can result in significant out of plane artifacts while large angular acquisition span in CT can limit the imaging coverage of the chest wall near the breast. We propose a new breast imaging modality, wide-angle breast tomosynthesis (WBT), aimed to provide a practical compromise between 3D sampling and chest-wall coverage. This study compares lesion detection between conventional digital breast tomosynthesis, WBT, and breast CT (44°, 99°, and 198° total angle range, respectively) under equal patient dose conditions. A Monte Carlo (MC) code based on the Penelope package modeled a virtual flat-panel breast tomosynthesis system. The modalities were simulated at four breast compression levels. Glandular dose to the breast was estimated and the radiation flux was subsequently adjusted to achieve a constant mean glandular dose level of 1.5 mGy, independent of the breast thickness and acquisition geometry. Reconstructed volumes were generated using iterative reconstruction methods. Lesion detectability was estimated using contrast-to-noise-ratio. Results showed improved detection with increased angular span and compression. Evaluations also showed improved performance of WBT over DBT at lower compression levels, therefore highlighting potential for reduced breast compression when using a larger acquisition angle.

Thompson, John; Chen, Baiyu; Richard, Samuel; Bowsher, James; Samei, Ehsan

2010-04-01

420

High-speed angle-resolved imaging of a single gold nanorod with microsecond temporal resolution and one-degree angle precision.  

PubMed

We developed two types of high-speed angle-resolved imaging methods for single gold nanorods (SAuNRs) using objective-type vertical illumination dark-field microscopy and a high-speed CMOS camera to achieve microsecond temporal and one-degree angle resolution. These methods are based on: (i) an intensity analysis of focused images of SAuNR split into two orthogonally polarized components and (ii) the analysis of defocused SAuNR images. We determined the angle precision (statistical error) and accuracy (systematic error) of the resultant SAuNR (80 nm × 40 nm) images projected onto a substrate surface (azimuthal angle) in both methods. Although both methods showed a similar precision of ?1° for the azimuthal angle at a 10 ?s temporal resolution, the defocused image analysis showed a superior angle accuracy of ?5°. In addition, the polar angle was also determined from the defocused SAuNR images with a precision of ?1°, by fitting with simulated images. By taking advantage of the defocused image method's full revolution measurement range in the azimuthal angle, the rotation of the rotary molecular motor, F1-ATPase, was measured with 3.3 ?s temporal resolution. The time constants of the pauses waiting for the elementary steps of the ATP hydrolysis reaction and the torque generated in the mechanical steps have been successfully estimated. The high-speed angle-resolved SAuNR imaging methods will be applicable to the monitoring of the fast conformational changes of many biological molecular machines. PMID:25647635

Enoki, Sawako; Iino, Ryota; Niitani, Yamato; Minagawa, Yoshihiro; Tomishige, Michio; Noji, Hiroyuki

2015-02-17