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1

Atmospheric aerosol retrieval from thermal infrared nadir sounding - preliminary results  

NASA Astrophysics Data System (ADS)

To further the exploitation of the Infrared Atmospheric Sounding Interferometer (IASI) to be launched onboard METOP-1 in 2005, we have developed an algorithm to retrieve aerosol features from nadir-looking high-spectral resolution spectrometers operating in the thermal infrared. Occurrences of significant aerosol concentrations at low altitude such as Sahara dust or biomass burning affect nadir infrared radiance measurements while stratospheric aerosols don't, except in case of a high, fresh volcanic aerosol load. The sensitivity of the radiance measurements to low-altitude aerosols is highest in the atmospheric window and is dominated by the contrast between the surface temperature and the air temperature where the aerosols are located. The impact on the spectral radiances observed at the top of the atmosphere consists mainly of broadband absorption features. Our retrieval algorithm is based on the comparison between observed and synthetic spectral radiances in the 700--1400 cm-1 window, in cases where the above-mentioned temperature contrast is high enough. The synthetic radiances are calculated using the surface and atmospheric conditions corresponding to the observed radiances but in the absence of clouds and aerosol. The atmospheric molecular concentrations can be obtained from the observed spectra because the retrieval of gaseous species is based mainly on the shape of several narrow absorption lines and is therefore hardly sensitive to broadband features. In the selected window the significant absorptions are limited to O3, H2O and CO2. The surface and atmospheric temperatures are obtained from ancillary data. The algorithm has been verified using spectral radiances measured over sea by the IMG instrument onboard ADEOS, which has been operational between October'96 and June'97. For fast processing purposes, the clear-sky synthetic radiances are calculated with the MODTRAN band model, using surface temperatures and atmospheric profiles from ERA-40 (ECMWF). To assess the suitability of this procedure, some cases have been verified using atmospheric profiles obtained by inversion of the IMG spectral radiances themselves with the help of a line-by-line code. Preliminary results are presented and compared to aerosol optical thicknesses obtained at 865 nm as obtained by the POLDER instrument, also onboard the ADEOS payload.

Kruglanski, M.; de Mazière, M.; Vandaele, A.-C.; Hurtmans, D.

2

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

3

Sensitivity of off-nadir zenith angles to correlation between visible and near-infrared reflectance for use in remote sensing of aerosol over land  

Microsoft Academic Search

Cloud absorption radiometer (CAR) multispectral and multiangular data, collected during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) Experiment, was used to examine the ratio technique, the official method for remote sensing of aerosols over land from the moderate resolution imaging spectroradiometer (MODIS) data, for view angles from nadir to 650 off-nadir. The strategy used is to first select a pristine, low

Charles K. Gatebe; Michael D. King; Si-Chee Tsay; Q. Ji; G. Thomas Arnold; Jason Y. Li

2001-01-01

4

Boundary layer aerosol retrieval from thermal infrared nadir sounding Preliminary results  

NASA Astrophysics Data System (ADS)

A non-empirical algorithm is presented to retrieve the optical depth in the 750 1250 cm-1 spectral range, of aerosol located in the boundary layer over the ocean, from nadir high-resolution radiance spectra in the thermal infrared. The algorithm is based on a line-by-line radiative transfer forward model and used the Optimal Estimation Method for the retrieval. Its performance strongly depends on the quality of the a priori temperature and H2O atmospheric profiles. To demonstrate the relevance of the algorithm, distributions of maritime aerosol parameters have been retrieved from IMG/ADEOS data for December 1996, using the algorithm with the LBLRTM radiative transfer code, and ERA40 (ECMWF) a priori atmospheric profiles and surface conditions.

Kruglanski, M.; de Mazière, M.; Vandaele, A. C.; Hurtmans, D.

5

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

6

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

7

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

8

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

9

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

10

Angles  

NSDL National Science Digital Library

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

Clark, Mr

2012-10-31

11

Angles  

NSDL National Science Digital Library

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

Edkins, Jo

2007-01-01

12

Brook Trout Angling in Maine 2009 Survey Results  

E-print Network

Brook Trout Angling in Maine 2009 Survey Results Marc Edwards University of Maine Cooperative of Inland Fisheries and Wildlife's Wild Brook Trout Initiative for five fishing guides from the greater of Maine's unique wild brook trout fishery could more effectively be promoted to attract anglers seeking

Thomas, Andrew

13

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

Foundation, Shodor E.

2004-01-01

14

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.

2011-03-04

15

Results from the G0 forward angle measurement  

SciTech Connect

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

J. Liu

2006-07-01

16

Mars Odyssey: Off-nadir Imaging  

NASA Technical Reports Server (NTRS)

Science Objectives for off-nadir imaging: a) Daily observations of high activity and high interest targets in the Polar Regions; b) Daily imaging of regions of gas jetting through vents and the formation of dark spots and fans; c) Increases likelihood of observing these processes in an active phase; d) Stereo imaging for geographical analysis and landing site characterization; and e) Fill in existing gaps and gores.

Polanskey, Carol A.

2006-01-01

17

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

18

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

19

Angled Injection: Turbulent Flow Hybrid Bearings Comparison to Test Results  

NASA Technical Reports Server (NTRS)

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

SanAndres, Luis; Childs, Dara

1997-01-01

20

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

21

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

22

Nadir Observations of Lightning and TLEs by JEM-GLIMS  

NASA Astrophysics Data System (ADS)

JEM-GLIMS is a space mission to observe lightning and lightning-associated Transient Luminous Events (TLEs) from the Exposed Facility (EF) of the Japanese Experiment Module (JEM) at the International Space Station (ISS). The main purpose of this mission is to carry out the nadir observations of these phenomena and to identify temporal and spatial evolutions of lightning and TLEs and to clarify the occurrence conditions of TLEs and global occurrence locations and rates of TLEs. JEM-GLIMS consists of two optical instruments, two radio receivers, and one onboard computer. The optical instruments are two CMOS cameras (LSI-1, LSI-2) and six-channel spectrophotometers (PH1 - PH6). The FOV of LSI is 28.3 deg. x 28.3 deg., and LSI-1 (LSI-2) equips a 766-832 nm wide band filter (a 762+/-7 nm narrow band filter). Each PH channel equips the optical band-pass filter, and these photometers measure the N2 1P, N2 2P, N2 LBH, and N2+ 1N emissions of lightning and TLEs. The radio receivers consist of one VLF receiver (VLFR) and two sets of VHF receivers (VITF). In order to detect TLE-associated whistler waves, VLFR employs a nadir-directing monopole antenna and an electronics unit recording waveform data with a sampling frequency of 100 kHz with 14-bit resolution. VITF consists of two patch-type antennas separated by 1.5 m and an electronics unit, and VITF mainly observes VHF pulses in the frequency range of 70-100 MHz excited by lightning discharges with a sampling frequency of 200 MHz with 8-bit resolution. JEM-GIMS was successfully launched and transported to the ISS by the H-II Transfer Vehicle (HTV) No.3 cargo transporter at the end of July 2012, and was installed at JEM-EF on August 9. For the period from September 15 to November 12 we have carried out the initial checkout operation and confirmed that the functions of all the instruments are normal and that the performance of all the science instruments is identical with that before launch. Finally, we have started the continuous observations of lightning and TLEs from November 20, 2012. Up to the end of December 2012, JEM-GLIMS has triggered and recorded 221 transient optical events in total, where strong lightning signatures are confirmed in LSI and PH channels. For some of these events, transient signatures of N2 LBH are confirmed in the PH1 channel, which strongly implies the occurrence of TLEs. At the presentation we will report more detailed initial results derived from JEM-GLIMS data.

Sato, Mitsuteru; Ushio, Tomoo; Morimoto, Takeshi; Suzuki, Makoto; Yamazaki, Atsushi; Kikuchi, Masayuki; Takahashi, Yukihiro; Inan, Umran; Linscott, Ivan; Hobara, Yasuhide

2013-04-01

23

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

24

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

E-print Network

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; 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; Blecki, J; Blin-Bondil, S; Bluemer, 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; Cortes, 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; Fernandez-Gomez, I; Ferrarese, S; Franceschi, A; Fujimoto, J; Galeotti, P; Garipov, G; Geary, J; Giaccari, U G; Giraudo, G; Gonchar, M; Alvarado, C Gonzalez; Gorodetzky, P; Guarino, F; Guzman, A; Hachisu, Y; Harlov, B; Haungs, A; Carretero, J Hernandez; Higashide, K; Iguchi, T; Ikeda, H; Inoue, N; Inoue, S; Insolia, A; Isgrio, 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; Lopez, 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; Rios, J A Morales de los; 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; Orleanski, 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; Rodriguez, I; Frias, M D Rodriguez; Ronga, F; Rothkaehl, H; Roudil, G; Rusinov, I; Rybczynski, M; Sabau, M D; Cano, G Saez; Saito, A; Sakaki, N; Sakata, M; Salazar, H; Sanchez, S; Santangelo, A; Cruz, L Santiago; Palomino, M Sanz; 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, G; Lopez, H H Silva; Sledd, J; Slominska, 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; Valdes-Galicia, J F; Vallania, P; Valore, L; Vankova, G; Vigorito, C; Villasenor, 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; Wlodarczyk, Z; Yamamoto, T; Yamamoto, Y; Yang, J; Yano, H; Yashin, I V; Yonetoku, D; Yoshida, K; Yoshida, S; Young, R; Zamora, A; Marchi, A Zuccaro; 10.1016/j.astropartphys.2013.01.008

2013-01-01

25

Nadir looking airborne radar and possible applications to forestry  

Microsoft Academic Search

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

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

1987-01-01

26

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

27

Resonant scattering and resultant pitch angle evolution of relativistic electrons by plasmaspheric hiss  

NASA Astrophysics Data System (ADS)

Adopting several realistic models for the wave distribution and ambient plasmaspheric density, we perform a comprehensive analysis to evaluate hiss-induced scattering coefficients, the relative role of each resonant harmonic, and the overall effect of hiss scattering on the pitch angle evolution and associated decay (loss) processes of relativistic electrons. The results show that scattering by the equatorial, highly oblique component of the hiss emission is negligible. A quasi-parallel propagating wave model of hiss emissions provides a good approximation for evaluation of scattering rates of ? 2 MeV electrons. However, realistic wave propagation angles as a function of latitude along the field line must be taken into account to accurately quantify the rates of hiss scattering above 2 MeV. Ambient plasma density is also a critical parameter that can influence hiss scattering rates and resultant pitch angle evolution of electron flux. While the first order cyclotron and the Landau resonances are dominant for hiss-induced scattering of less than 2 MeV electrons, higher order resonances become important and even dominant at intermediate equatorial pitch angles for ultra-relativistic (? 3 MeV) electrons. Hiss induced electron pitch angle evolution consistently shows a relatively rapid initial transport of electrons from high to lower pitch angles, with a gradual approach towards an equilibrium shape, and a final state where the entire distribution decays exponentially with time. Although hiss scattering rates near the loss cone control the pitch angle evolution and the ultimate loss of ultra-relativistic electrons, the presence of a scattering bottleneck (a pronounced drop in diffusion rate at intermediate pitch angles) significantly affects the loss rate and leads to characteristic top hat shaped pitch angle distributions at energies below ~1 MeV. Decay timescales are determined to be on the order of a few days, tens of days, and > 100 days for 500 keV, 2 MeV, and 5 MeV electrons, respectively, which is consistent with recent observations from the Van Allen probes, and indicates that scattering by hiss emissions can realistically account for the long-term loss process and the pitch angle evolution of relativistic electrons in the plasmasphere following injection during storm conditions.

Ni, B.; Bortnik, J.; Thorne, R. M.; Ma, Q.; Chen, L.

2013-12-01

28

First-Day Newborn Weight Loss Predicts In-Hospital Weight Nadir for Breastfeeding Infants  

PubMed Central

Abstract Background Exclusive breastfeeding reduces infant infectious disease. Losing ?10% birth weight may lead to formula use. The predictive value of first-day weight loss for subsequent weight loss has not been studied. The objective of the present study was to evaluate the relationship between weight loss at <24 hours and subsequent in-hospital weight loss ?10%. Methods For 1,049 infants, we extracted gestational age, gender, delivery method, feeding type, and weights from medical records. Weight nadir was defined as the lowest weight recorded during birth hospitalization. We used multivariate logistic regression to assess the effect of first-day weight loss on subsequent in-hospital weight loss. Results Mean in-hospital weight nadir was 6.0?±?2.6%, and mean age at in-hospital weight nadir was 38.7?±?18.5 hours. While in the hospital 6.4% of infants lost ?10% of birth weight. Infants losing ?4.5% birth weight at <24 hours had greater risk of eventual in-hospital weight loss ?10% (adjusted odds ratio 3.57 [1.75, 7.28]). In this cohort, 798 (76.1%) infants did not have documented weight gain while in the hospital. Conclusions Early weight loss predicts higher risk of ?10% in-hospital weight loss. Infants with high first-day weight loss could be targeted for further research into improved interventions to promote breastfeeding. PMID:20113202

Bokser, Seth; Newman, Thomas B.

2010-01-01

29

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

30

HELIOS, a nadir-looking sea ice monitoring camera  

Microsoft Academic Search

We present the prototype of a simplified photogrammetric system (HELicopter-borne Ice Observation System, HELIOS) and demonstrate how it can be used to document ground-based and airborne sea ice surveys. The aerial unit consists of a nadir-looking digital camera mounted on a gimbal, a GPS receiver and a computer. It is of low-cost and weight and is designed such that it

Thomas Krumpen; Christian Haas; Stefan Hendricks; Jens A. Hölemann; Dirk Kalmbach; Rüdiger Gerdes

2011-01-01

31

Results of piloted simulator studies of fighter aircraft at high angles of attack  

NASA Technical Reports Server (NTRS)

The experience gained at the NASA Langley Research Center during the application of simulator techniques to high angle of attack flight conditions for several current fighters is discussed. The discussion includes (1) the simulator hardware, (2) requirements for static and dynamic aerodynamic data inputs, (3) evaluation procedures, (4) correlation with flight, and (5) the effects of dynamic stability parameters. Results obtained with the simulator technique have correlated well with flight test experience, resulting in early identification of potential problems, identification of critical flight conditions, and solutions to various deficiencies in stability and control characteristics. Dynamic stability parameters, results indicate that certain parameters can have a large influence on the flying qualities and tactical effectiveness of fighters at high angles of attack.

Chambers, J. R.; Gilbert, W. R.; Nguyen, L. T.

1978-01-01

32

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

33

Mjølnir Crater as a Result of Oblique Impact: Asymmetry Evidence Constrains Impact Direction and Angle  

Microsoft Academic Search

The 40-km-diameter Mjølnir crater is proposed to have resulted from an oblique impact from the south\\/southwest direction and\\u000a at a ~45° (possibly 30°–45°) angle from the horizontal. This is substantiated by several diagnostic structural and geophysical\\u000a signatures related to obliquity and revealed through detailed re-assessment of Mjølnir’s well-established structure, morphology,\\u000a and gravity and seismic velocity anomalies. The diagnostic signatures include:

Filippos Tsikalas

2005-01-01

34

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

35

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! ...

Smith, Miss

2011-03-23

36

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

37

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

38

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

39

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

2014-11-27

40

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

41

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

42

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

Atmospheric Science Data Center

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

2014-12-09

43

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

Atmospheric Science Data Center

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

2014-12-10

44

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

PubMed Central

Purpose To report surgical results of canaloplasty surgery for primary open-angle glaucoma (POAG) in Japanese patients. Methods Eleven eyes of 9 POAG patients underwent canalopasty surgery at Toyama University Hospital. Three eyes of 3 patients underwent canaloplasty alone and 8 eyes of 6 patients underwent canaloplasty combined with cataract surgery. Canaloplasty was performed with a 10-0 polypropylene tensioning suture and an iTrack™ 250A microcatheter. All patients were followed up for 12 months. Changes in intraocular pressure (IOP) and postoperative complications were examined. Results Mean preoperative IOP was 23.4 ± 5.5 mm Hg. Mean number of antiglaucoma drops was 2.8 ± 0.6 before canaloplasty and decreased to 1.2 ± 0.8 at 12 months after canaloplasty (p < 0.01). Mean IOP decreased postoperatively, being 13.7 ± 2.8 mm Hg at 1 month, 12.8 ± 3.5 mm Hg at 3 months, 14.0 ± 4.4 mm Hg at 6 months, and 15.0 ± 4.1 mm Hg at 12 months. The most frequent postoperative complication was mild hyphema (45.5%), which disappeared within 14 days after surgery. Conclusions Canaloplasty may be an alternative surgery for POAG patients to reduce IOP to a value of approximately 15 mm Hg. PMID:21475647

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

2011-01-01

45

Effects of Nadir CD4 Count and Duration of HIV Infection on Brain Volumes in the HAART Era  

PubMed Central

Background Cerebral atrophy is a well described, but poorly understood complication of HIV infection. Despite reduced prevalence of HIV-associated dementia in the HAART era, HIV continues to affect the brains of patients with chronic infection. In this study we examine patterns of brain volume loss in HIV infected patients on HAART, and demographic and clinical factors contributing to it. We hypothesized that nadir CD4+ lymphocyte count, duration of HIV infection and age would be associated with reduced cortical volumes. Methods Volumes of cortical and subcortical regions in 69 HIV-infected neuroasymptomatic (NA) individuals and 13 with at least mild AIDS dementia complex (ADC) were measured using voxel-based morphometry. Demographic and clinical factors (age, plasma HIV RNA level, current and nadir CD4 count, duration of infection, CNS penetration of antiretroviral regimen) along with their interactions were entered into a regression model selection algorithm to determine the final models that best described regional brain volumes. Results Relative to NA, individuals with ADC exhibited decreased total gray matter and parietal cortex volumes and increased total ventricular volumes. Final regression models showed overall cerebral volume, including gray and white matter volume and volumes of the parietal, temporal, and frontal lobes and the hippocampus, were most strongly associated with disease history factors (nadir CD4 and duration of infection). In contrast, basal ganglia volumes were related most strongly to current disease factors, most notably plasma HIV RNA. Conclusions These findings indicate that individuals with a history of chronic HIV infection with previous episodes of severely impaired immune function, as reflected by reduced nadir CD4 + lymphocyte count, may be at greatest risk for cerebral atrophy. The pattern of HIV-associated brain loss may be changing from a subcortical to a cortical disease among patients who are largely asymptomatic on HAART. PMID:20113183

Cohen, Ronald A.; Harezlak, Jaroslaw; Schifitto, Giovanni; Hana, George; Clark, Uraina; Gongvatana, Assawin; Paul, Robert; Taylor, Michael; Thompson, Paul; Algers, Jeffery; Brown, Mark; Zhong, Jianhui; Campbell, Thomas; Singer, Elyse; McMahon, Deborah; Tso, Yuen; Yiannoutsos, Constantin T; Navia, Bradford

2010-01-01

46

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

47

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

48

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

49

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

50

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

NASA Astrophysics Data System (ADS)

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

Ma, Xiaodong; Rudnicki, John; Haimson, Bezalel

2014-05-01

51

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

52

Nadir and Limb Viewing Observations of Polar Mesospheric Clouds from the Aeronomy of Ice in the Mesosphere (AIM) Explorer  

NASA Astrophysics Data System (ADS)

The Cloud Imaging and Particle Size (CIPS) instrument on the AIM spacecraft is a 4-camera nadir pointed imager with a bandpass centered at 265 nm and a field of view of 120 by 80 degrees. CIPS observes Polar Mesospheric Clouds (PMCs) against the sunlit Rayleigh-scattered background. At individual polar locations approximately 5km by 5km in area, CIPS observes the same volume of air multiple times over a range of scattering angles from about 35 to 150 degrees. These multi-angle observations allow the identification and extraction of the PMC scattered radiance from the Rayleigh-scattered background. From this is obtained the ice albedo and particle size. At the summer terminator on each orbit, the Solar Occultation For Ice Experiment (SOFIE) views a common cloud volume with CIPS. SOFIE uses solar occultation in 16 channels (.3 to 5 microns) to obtain ice properties including particle size mean radius and concentration in addition to temperature, water vapor abundance, and other environmental parameters. In this talk, we discuss comparisons of the CIPS and SOFIE observations. We show that CIPS reveals significant structure along the limb path observed by SOFIE. We use SOFIE retrieved cloud parameters to make predictions of CIPS common volume-average observations and compare those to the actual CIPS data. The data show excellent correlation, but some systematic differences. We present evidence that those systematic differences are related to commonly applied assumptions regarding the shape of the particle size distribution.

Bailey, S. M.; Randall, C. E.; Lumpe, J. D.; Hervig, M. E.; Thomas, G. E.; Russell, J. M.

2012-12-01

53

Development of a Model to Correct Multi-View Angle above Water Measurements for the Analysis of the Bidirectional Reflectance of Coral and Other Reef Substrates  

NASA Astrophysics Data System (ADS)

Spectral reflectance characteristics of substrates in a coral reef environment are often measured in the field by viewing a substrate at nadir. However, viewing a substrate from multiple angles would likely result in different spectral characteristics for most coral reef substrates and provide valuable information on structural properties. To understand the relationship between the morphology of a substrate and its spectral response it is necessary to correct the observed above-water radiance for the effects of atmosphere and water attenuation, at a number of view and azimuth angles. In this way the actual surface reflectance can be determined. This research examines the air-water surface interaction for two hypothetical atmospheric conditions (clear Rayleigh scattering and totally cloudcovered) and the global irradiance reaching the benthic surface. It accounts for both water scattering and absorption, with simplifications for shallow water conditions, as well as the additive effect of background reflectance being reflected at the water-air surface at angles greater than the critical refraction angle (~48°). A model was developed to correct measured above-water radiance along the refracted view angle for its decrease due to path attenuation and the "n squared law of radiance" and the additive surface reflectance. This allows bidirectional benthic surface reflectance and nadir-normalised reflectance to be determined. These theoretical models were adapted to incorporate above-water measures relative to a standard, diffuse, white reference panel. The derived spectral signatures of a number of coral and non-coral benthic surfaces compared well with other published results, and the signatures and nadir normalised reflectance of the corals and other benthic surface classes indicate good class separation.

Miller, I.; Forster, B. C.; Laffan, S. W.

2012-07-01

54

Interaction between oblique-angled incident shock wave and turbulent boundary layer on a heated wall. Experimental results  

NASA Astrophysics Data System (ADS)

The interaction resulting from the reflection of an incident oblique-angled shock wave on a turbulent boundary layer, developed on a heated wall, is investigated. The experiments are carried out in a 2-D plane device, with a Mach number equal to 2.4. Two different incident shock wave intensities are considered. The interactions are examined under adiabatic conditions and for a wall heating ratio of T sub p/T sub f=2. The observations were performed by means of temperature and pressure sounding techniques and laser anemometry.

Stalter, M.; Delery, J.

1989-03-01

55

Recent Results from the Wide Angle Search for Planets (WASP) Prototype  

NASA Astrophysics Data System (ADS)

WASP0 is a prototype for what is intended to become a collection of WASPs whose primary aim is to detect transiting extra-solar planets across the face of their parent star. We present some recent results from the WASP0 camera, including observations of the known transiting planet around HD 209458. The current status of the next generation camera (SuperWASP) located on La Palma is briefly outlined.

Kane, S. R.; Horne, K.; Lister, T.; Collier Cameron, A.; Street, R. A.; Pollacco, D. L.; James, D.; Tsapras, Y.

2004-12-01

56

Recent Results from the Wide Angle Search for Planets (WASP) Prototype  

NASA Astrophysics Data System (ADS)

WASP0 is a prototype for what is intended to become a collection of WASPs whose primary aim is to detect transiting extrasolar planets across the face of their parent star. The WASP0 instrument is a wide-field (9-degree) 6.3 cm aperture F/2.8 Apogee 10 CCD camera (2Kx2K chip, 16-arcsec pixels). The camera is mounted piggy-back on a commercial 10-inch Meade telescope. We present some recent results from the WASP camera, including observations from La Palma of the known transiting planet around HD 209458 and preliminary analysis of other stars located in the same field. We also outline further problems which restrict the ability to achieve photon limited precision with a wide-field commercial CCD.

Kane, S. R.; Horne, K.; Street, R. A.; Pollaco, D. L.; James, D.; Tsapras, Y.; Collier Cameron, A.

57

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

58

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

59

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

60

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

61

Aerosol Properties from Multi-angle Satellite Imaging  

Microsoft Academic Search

The MISR instrument, flying aboard the NASA Earth Observing System's Terra satellite, is pioneering the use of multi-angle imaging to monitor aerosols globally, from space. MISR obtains nine along-track images at view angles ranging from +70o through nadir to -70o, in each of four wavelengths, near-simultaneously. The instrument systematically covers air-mass-factors between one and three, and in mid-latitudes, samples scattering

R. A. Kahn; J. V. Martonchik; D. J. Diner; O. Kalashnikova

2004-01-01

62

Differing angles on angle  

Microsoft Academic Search

Values of plane angles are expressed with a choice of several units. Historically the quantity needed a unit because it was, and still is, used as a base quantity. ISO\\/TC 12 defines it as a derived, dimensionless quantity, and the International System of Units (SI) gives it the ‘dimensionless unit’ radian, which now means no more than ‘one’. This paper

W H Emerson

2005-01-01

63

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

64

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

65

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

66

Equivalent Biochemical Control and Improved Prostate-Specific Antigen Nadir After Permanent Prostate Seed Implant Brachytherapy Versus High-Dose Three-Dimensional Conformal Radiotherapy and High-Dose Conformal Proton Beam Radiotherapy Boost  

SciTech Connect

Purpose: Permanent prostate implant brachytherapy (PPI), three-dimensional conformal radiotherapy (3D-CRT), and conformal proton beam radiotherapy (CPBRT) are used in the treatment of localized prostate cancer, although no head-to-head trials have compared these modalities. We studied the biochemical control (biochemical no evidence of disease [bNED]) and prostate-specific antigen (PSA) nadir achieved with contemporary PPI, and evaluated it against 3D-CRT and CPBRT. Patients and Methods: A total of 249 patients were treated with PPI at the University of California, San Francisco, and the outcomes were compared with those from a 3D-CRT cohort and the published results of a high-dose CPBRT boost (CPBRTB) trial. For each comparison, subsets of the PPI cohort were selected with patient and disease criteria similar to those of the reference group. Results: With a median follow-up of 5.3 years, the bNED rate at 5 and 7 years achieved with PPI was 92% and 86%, respectively, using the American Society for Therapeutic Radiology and Oncology (ASTRO) definition, and 93% using the PSA nadir plus 2 ng/mL definition. Using the ASTRO definition, a 5-year bNED rate of 78% was achieved for the 3D-CRT patients compared with 94% for a comparable PPI subset and 93% vs. 92%, respectively, using the PSA nadir plus 2 ng/mL definition. The median PSA nadir for patients treated with PPI and 3D-CRT was 0.10 and 0.40 ng/mL, respectively (p < .0001). For the CPBRT comparison, the 5-year bNED rate after a CPBRTB was 91% using the ASTRO definition vs. 93% for a similar group of PPI patients. A greater proportion of PPI patients achieved a lower PSA nadir compared with those achieved in the CPBRTB trial (PSA nadir <=0.5 ng/mL, 91% vs. 59%, respectively). Conclusion: We have demonstrated excellent outcomes in low- to intermediate-risk patients treated with PPI, suggesting at least equivalent 5-year bNED rates and a greater proportion of men achieving lower PSA nadirs compared with 3D-CRT or CPBRTB.

Jabbari, Siavash [Department of Radiation Oncology, University of California San Francisco, School of Medicine, San Francisco, CA (United States); Weinberg, Vivian K. [Department of Urology, University of California San Francisco, School of Medicine, San Francisco, CA (United States); Shinohara, Katsuto [Department of Biostatistics Core, University of California San Francisco, School of Medicine, San Francisco, CA (United States); Speight, Joycelyn L. [Department of Radiation Oncology, University of California San Francisco, School of Medicine, San Francisco, CA (United States); Department of Biostatistics Core, University of California San Francisco, School of Medicine, San Francisco, CA (United States); Gottschalk, Alexander R.; Hsu, I.-C.; Pickett, Barby [Department of Radiation Oncology, University of California San Francisco, School of Medicine, San Francisco, CA (United States); McLaughlin, Patrick W.; Sandler, Howard M. [Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, MI (United States); Roach, Mack, E-mail: mroach@radonc.ucsf.ed [Department of Radiation Oncology, University of California San Francisco, School of Medicine, San Francisco, CA (United States); Department of Urology, University of California San Francisco, School of Medicine, San Francisco, CA (United States)

2010-01-15

67

First satellite ozone distributions retrieved from nadir high-resolution infrared spectra  

NASA Astrophysics Data System (ADS)

The Interferometric Monitor for Greenhouse Gases (IMG) on board the Japanese ADEOS platform provided the first high resolution atmospheric spectra allowing the simultaneous measurement of several IR absorbing species, including ozone. The paper describes the retrieval of total column ozone fields from nadir radiances, using an inversion algorithm developed for the Infrared Atmospheric Sounding Interferometer (IASI). The accuracy and sensitivity of the retrieved concentrations are assessed. The global distributions obtained from the available IMG/ADEOS Level 1C data are shown to be in good agreement with the TOMS/ADEOS (Total Ozone Mapping Spectrometer) Level 2 measurements.

Turquety, Solène; Hadji-Lazaro, Juliette; Clerbaux, Cathy

2002-12-01

68

Results of a modified non-penetrating deep sclerectomy in the treatment of open angle glaucoma with or without cataract  

PubMed Central

Purpose: To present the technique of a modified deep sclerectomy, which we will call “reversed” deep sclerectomy (RDS) and the results and our observations of its use in patients with open angle glaucoma (OAG) and with or without cataract extraction (phacoemulsification). Materials and methods: This prospective study included 132 eyes which underwent RDS: 37 eyes (group A) with uncontrolled OAG and 95 eyes (group B) with OAG and visually significant cataract. Mean pressure preoperatively for group A was 24.48 ± 4.92 mmHg and for group B was 22.99 ± 3.00. The mean number of antiglaucoma drugs received was 2.97 ± 0.69 and 2.56 ± 0.73 for groups A and B respectively. The RDS was performed where the deep scleral stroma is prepared in 2 parts, folded and inserted under the lateral sides of the sclerectomy, and the Schlemm’s canal is opened prior to deep scleral stroma preparation. Cataract was extracted by phacoemulsification through the same scleral opening. The follow-up for group A was 22.23 ± 10.18 months and for group B, 25.36 ± 10.12 months. Results: Postoperative intraocular pressure (IOP) ? 21 mmHg was achieved for group A in 40.5% without antiglaucoma drugs and 94.6% with antiglaucoma drugs, and for group B in 66.3% and in 94.7% respectively. Mean IOP reduction was 7.02 ± 6.35 mmHg (28.67%, P < 0.05) for group A and 5.26 ± 3.72 mmHg (25.06%, P ? 0.05) for group B, while mean drug reduction was 1.97 ± 1.09 (P < 0.01) and 2.14 ± 0.95 (P ? 0.01) respectively. 5-Fluorouracil was used in 8 eyes of group A and in 5 eyes of group B. Conclusion: In the follow-up time during which the two groups were under study, the RDS was effective with a few complications, similar to the classic deep sclerectomy using implants or not, with the advantage, in our opinion, of a short learning curve. PMID:20689784

Kitsos, George; Aspiotis, Miltiades; Alamanos, Yannis; Psilas, Konstantinos

2010-01-01

69

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

70

Preliminary investigation of the reststrahlen phenomenology at low-grazing angles  

NASA Astrophysics Data System (ADS)

Detection of buried and flush buried landmines has been dangerous and time consuming for both military and humanitarian de-mining personnel throughout the world. In an effort to make the process safer, faster, and more reliable, scientists have successfully employed Ground Penetrating Radar (GPR) systems in nadir and near nadir viewing angles. Leveraging this successful technology, Forward-Looking Ground Penetrating Radar (FLGPR) technology, using low grazing angles, is being developed which promises to provide an increase in detection stand-off distance thereby increasing safety of personnel during land-based mine detection efforts. However, the application of GPR for the detection of buried plastic mines has been problematic, research has begun to exploit the comination of broadband and hyper-spectral passive electro-optical technologies with GPR technologies. One such embodiment is to use Forward Looking InfraRed (FLIR) technology with the intention to augment the capability of, and overcome limitations inherent to, current FLGPR technology. The emphasis in using FLIR is to understand and exploit specific spectral features which are complementary fo FLGPR and exhibited by buried metal and plastic mine targets. One spectral feature being investigated is the resstrahlen emission which results when soil is excavated or disturbed. This paper is a preliminary investigation of the performance of a vehicle based FLIR camera system for detecting resstrahlen emissions from disturbed soils. Specifically, this paper will examine the robustness of the resstrahlen feature in a forward-looking low grazing angle application. The data presented in this paper was collected at an eastern US Army testing site over targets deployed in soils which had been disturbed from one day before the start of the collection.

Harr, Richard; Polcha, Michael

2005-06-01

71

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)

Mathematics, Illuminations N.

2010-05-20

72

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

73

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

74

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 ...

Hume, Ms.

2012-11-02

75

Subduction processes off chile (SPOC) - results from The amphibious wide-angle seismic experiment across The chilean subduction zone  

NASA Astrophysics Data System (ADS)

One component of the onshore-offshore, active-passive seismic experiment SPOC (Krawczyk et al., Stiller et al., this vol.) was a 2-D wide-angle seismic experiment covering the Chilean subduction zone from the Nazca Plate to the Magmatic Arc in the main cordillera. Three W-E-profiles of 52 stations each and up to 240 km long were deployed between 36° and 39° S. These profiles recorded chemical shots at their ends and, in order to extend the onshore profiles, the airgun pulses from RV SONNE cruising simultaneously on offshore profiles. On the southernmost of the three profiles OBHs/OBSs were deployed offshore, thus providing continuous wide-angle seismic data from the Nazca Plate to the South-American continent. Data examples, correlations, and velocity models along the three transects will be presented. The Moho of the subducted oceanic crust can be constrained by PmP-reflections down to 45 km depth under the coastal cordillera. The P-wave velocity field of the crust of the upper plate is characterized by gradually increasing P-wave velocities from East to West. Low seismic velocities (Vp < ~5 km/s) indicate the location of a young accretionary complex at the western tip of the continent. The highest seismic velocities (Vp > ~6.5 km/s below 10 km depth) are observed at the eastern margin of the investigated area.

Lueth, S.; Spoc Resaerch Group

2003-04-01

76

Detection of Martian dust clouds by SPICAM UV nadir measurements during the October 2005 regional dust storm  

NASA Astrophysics Data System (ADS)

The SPICAM UV spectrometer onboard Mars Express observed two regional dust storms: on October 24, 2005, near Argyre Planitia and on July 9, 2005, in Hellas Planitia. The measurements were performed in nadir mode. The spectral domain 210-310 nm is considered. A comparison with a prior orbit which passed above almost the same path 6 days before the storm near Argyre Planitia has shown a significant decrease of the radiance factor. The difference grows at shorter wavelengths and shows significant dust absorption in the UV. The data have been used to retrieve the dust optical thickness ?, single scattering albedo w and asymmetry factor g. The fitting of the spectra by a radiative transfer code has revealed a set of solutions which could be constrained by Mie modeling of the parameters ?, w, and g for a gamma particle size distribution. The following estimates of the dust optical parameters are obtained: w = 0.64 ± 0.04 at ? = 300 nm and decreases to 0.6 ± 0.045 at 213 nm, g = 0.86 ± 0.03 at 300 nm and slightly grows to 0.88 ± 0.04 at 213 nm, ? = 2.5 ± 0.5 for the first dust event and ? = 2.0 ± 0.5 for the second one. The obtained values of single scattering albedo are consistent with the Hubble Space Telescope and Mariner 9 results.

Mateshvili, N.; Fussen, D.; Vanhellemont, F.; Bingen, C.; Dodion, J.; Montmessin, F.; Perrier, S.; Bertaux, J. L.

77

Retrieval of CO from nadir remote-sensing measurements in the infrared by use of four different inversion algorithms.  

PubMed

Four inversion schemes based on various retrieval approaches (digital gas correlation, nonlinear least squares, global fit adjustment, and neural networks) developed to retrieve CO from nadir radiances measured by such downward-looking satelliteborne instruments as the Measurement of Pollution in the Troposphere (MOPITT), the Tropospheric Emission Spectrometer (TES), and the Infrared Atmospheric Sounding Interferometer (IASI) instruments were compared both for simulated cases and for atmospheric spectra recorded by the Interferometric Monitor for Greenhouse Gases (IMG). The sensitivity of the retrieved CO total column amount to properties that may affect the inversion accuracy (noise, ancillary temperature profile, and water-vapor content) was investigated. The CO column amounts for the simulated radiance spectra agreed within 4%, whereas larger discrepancies were obtained when atmospheric spectra recorded by the IMG instrument were analyzed. The assumed vertical temperature profile is shown to be a critical parameter for accurate CO retrieval. The instrument's line shape was also identified as a possible cause of disagreement among the result provided by the groups of scientist who are participating in this study. PMID:12463254

Clerbaux, Cathy; Hadji-Lazaro, Juliette; Payan, Sébastien; Camy-Peyret, Claude; Wang, Jinxue; Edwards, David P; Luo, Ming

2002-11-20

78

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

79

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

80

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

81

Detection of Martian dust clouds by SPICAM UV nadir measurements during the October 2005 regional dust storm  

Microsoft Academic Search

The SPICAM UV spectrometer onboard Mars Express observed two regional dust storms: on October 24, 2005, near Argyre Planitia and on July 9, 2005, in Hellas Planitia. The measurements were performed in nadir mode. The spectral domain 210–310nm is considered. A comparison with a prior orbit which passed above almost the same path 6 days before the storm near Argyre

N. Mateshvili; D. Fussen; F. Vanhellemont; C. Bingen; J. Dodion; F. Montmessin; S. Perrier; J. L. Bertaux

2007-01-01

82

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

83

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

84

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

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

85

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

86

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

87

Remote sounding of atmospheric gravity waves with satellite limb and nadir techniques  

NASA Astrophysics Data System (ADS)

Recent advances in satellite techniques hold great potential for mapping global gravity wave (GW) processes at various altitudes. Poor understanding of small-scale GWs has been a major limitation to numerical climate and weather models for making reliable forecasts. Observations of short-scale features have important implication for validating and improving future high-resolution numerical models. This paper summarizes recent GW observations and sensitivities from several satellite instruments, including MLS, AMSU-A, AIRS, GPS, and CLAES. It is shown in an example that mountain waves with horizontal wavelengths as short as ˜30 km now can be observed by AIRS, reflecting the superior horizontal resolution in these modern satellite instruments. Our studies show that MLS, AMSU-A and AIRS observations reveal similar GW characteristics, with the observed variances correlated well with background winds. As a complementary technique, limb sounding instruments like CRISTA, CLAES, and GPS can detect GWs with better vertical but poorer horizontal resolutions. To resolve different parts of the broad GW spectrum, both satellite limb and nadir observing techniques are needed, and a better understanding of GW complexities requires joint analyses of these data and dedicated high-resolution model simulations.

Wu, Dong L.; Preusse, Peter; Eckermann, Stephen D.; Jiang, Jonathan H.; Juarez, Manuel De La Torre; Coy, Lawrence; Wang, Ding Y.

88

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

89

AcrySof phakic angle-supported intraocular lens for the correction of high to extremely high myopia: one-year follow-up results  

PubMed Central

AIM To assess the safety, efficacy and predictability of the AcrySof phakic angle-supported intraocular lens (IOL) (Alcon Inc., U.S.A.) for correction of high-to-extremely high myopia in adults. METHODS In this prospective study performed in Tianjin Medical University Eye Center & College of Optometry, Tianjin, China, 25 eyes of 13 patients were implanted with AcrySof phakic angle-supported IOLs and followed for 1 year postoperatively. Preoperative manifest refractive sphere was (-12.08±2.44) diopters (D) and cylinder was (-1.35±0.62)D. Visual acuity, predictability and stability of manifest refraction spherical equivalent (MRSE), adverse events, and endothelial cell density were analyzed during 1-year of follow-up. RESULTS After 1 year of follow-up, no eyes lost?1 line (best spectacle-corrected visual acuity)BSCVA; an uncorrected visual acuity (UCVA) of 20/20 or better was achieved in 60% of eyes; 100% had an UCVA of 20/40 or better; a BSCVA of 20/30 or better was achieved by 100% of eyes; 84% had a BSCVA of 20/20 or better. The overall mean percentage change in endothelial cell density 1 year after surgery was (-0.27±3.60)%. Two eyes (8%) had increased intraocular pressure (IOP) on the day of surgery. No pupil ovalization, pupillary block, or retinal detachment events were observed. CONCLUSION After 1 year of follow-up, the implantation of AcrySof phakic angle-supported IOL is proved to be safe, effective and predictable with minimal complications in patients with high-to-extremely high myopia. Due to the limitation of visiting time, long-term of clinical investigation is necessary to verify the safety and efficacy of this IOL. PMID:22773988

Yang, Rui-Bo; Zhao, Shao-Zhen

2012-01-01

90

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

91

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

92

A randomized control trial to evaluate the effect of adjuvant selective laser trabeculoplasty versus medication alone in primary open-angle glaucoma: preliminary results  

PubMed Central

Background The objective of this study was to investigate the effects of adjuvant selective laser trabeculoplasty (SLT) versus medication alone on intraocular pressure (IOP) control, medication use, and quality of life in patients with primary open-angle glaucoma. Methods This prospective, randomized control study recruited 41 consecutive primary open-angle glaucoma subjects with medically-controlled IOP ?21 mmHg. The SLT group (n=22) received a single 360-degree SLT treatment. The medication-only group (n=19) continued with their usual treatment regimen. In both groups, medication was titrated to maintain a target IOP defined as a 25% reduction from baseline IOP without medication, or <18 mmHg, whichever was lower. Outcomes, which were measured at baseline and at 6 months, included the Glaucoma Quality of Life-15 (GQL-15) and Comparison of Ophthalmic Medications for Tolerability (COMTOL) survey scores, IOP, and the number of antiglaucoma medicines. Results The baseline IOP was 15.8±2.7 mmHg and 14.5±2.5 mmHg in the SLT and medication-only groups, respectively (P=0.04). Both groups had a comparable number of baseline medication (P=0.2), GQL-15 (P=0.3) and COMTOL scores (P=0.7). At 6 months, the SLT group had a lower IOP (P=0.03) and required fewer medications compared with both baseline (P<0.0001) and with the medication-only group (P=0.02). There was no statistically significant difference in the 6-month GQL-15 or COMTOL score as compared to baseline (P?0.4) or between the two treatment groups (P?0.2). Conclusion A single session of adjuvant SLT provided further reductions in IOP and medication without substantial changes in quality of life or medication tolerability at 6 months. PMID:25284983

Lee, Jacky WY; Chan, Catherine WS; Wong, Mandy OM; Chan, Jonathan CH; Li, Qing; Lai, Jimmy SM

2014-01-01

93

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

94

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

95

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

96

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

97

Angle performance on optima MDxt  

NASA Astrophysics Data System (ADS)

Angle control on medium current implanters is important due to the high angle-sensitivity of typical medium current implants, such as halo implants. On the Optima MDxt, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through six narrow slits, and any angle adjustment is made by electrostatically steering the beam, while cross-wafer beam parallelism is adjusted by changing the focus of the electrostatic parallelizing lens (P-lens). In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen prior to implant. A variety of tests were run to measure the accuracy and repeatability of Optima MDxt's angle control. SIMS profiles of a high energy, channeling sensitive condition show both the cross-wafer angle uniformity, along with the small-angle resolution of the system. Angle repeatability was quantified by running a channeling sensitive implant as a regular monitor over a seven month period and measuring the sheet resistance-to-angle sensitivity. Even though crystal cut error was not controlled for in this case, when attributing all Rs variation to angle changes, the overall angle repeatability was measured as 0.16° (1?). A separate angle repeatability test involved running a series of V-curves tests over a four month period using low crystal cut wafers selected from the same boule. The results of this test showed the angle repeatability to be <0.1° (1?).

David, Jonathan; Kamenitsa, Dennis

2012-11-01

98

Angle performance on optima MDxt  

SciTech Connect

Angle control on medium current implanters is important due to the high angle-sensitivity of typical medium current implants, such as halo implants. On the Optima MDxt, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through six narrow slits, and any angle adjustment is made by electrostatically steering the beam, while cross-wafer beam parallelism is adjusted by changing the focus of the electrostatic parallelizing lens (P-lens). In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen prior to implant. A variety of tests were run to measure the accuracy and repeatability of Optima MDxt's angle control. SIMS profiles of a high energy, channeling sensitive condition show both the cross-wafer angle uniformity, along with the small-angle resolution of the system. Angle repeatability was quantified by running a channeling sensitive implant as a regular monitor over a seven month period and measuring the sheet resistance-to-angle sensitivity. Even though crystal cut error was not controlled for in this case, when attributing all Rs variation to angle changes, the overall angle repeatability was measured as 0.16 Degree-Sign (1{sigma}). A separate angle repeatability test involved running a series of V-curves tests over a four month period using low crystal cut wafers selected from the same boule. The results of this test showed the angle repeatability to be <0.1 Degree-Sign (1{sigma}).

David, Jonathan; Kamenitsa, Dennis [Axcelis Technologies, Inc., 108 Cherry Hill Dr, Beverly, MA 01915 (United States)

2012-11-06

99

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

100

Cenozoic tectonic evolution of the Ruby Mountains metamorphic core complex and adjacent basins: Results from normal-incidence and wide-angle multicomponent seismic data  

NASA Astrophysics Data System (ADS)

Seismic studies in the area of the Ruby Mountains metamorphic core complex and adjacent basins of northeast Nevada provide new evidence for Cenozoic tectonic evolution of the Ruby Mountains. Results from interpretation of industry seismic data show that (1) asymmetric basins flanking the Ruby Mountains were created by normal faults beginning in the late Eocene-early Oligocene; (2) the metamorphic core complex detachment fault system was cut by the normal fault system; and (3) total subsidences of Huntington and Lamoille basins, and Ruby basins are ˜4.5 and ˜5.0 km. Analysis of crustal-scale 3-component normal-incidence to wide-angle seismic data shows that (1) the crust along the eastern flank of the Ruby Mountains can be divided into three layers corresponding to the upper, middle and lower crust; (2) upper crustal rocks likely consist of metaquartzite, schist, granite gneiss, and granite-granodiorite with P-wave velocities (Vp) of 5.80-6.25 km/s, S-wave velocities (Vs) of 3.20-3.72 km/s, Poisson's ratios (sigma) of 0.22-0.25, and anisotropy of 0.6-2.5%; (3) possible middle crustal rocks are paragranulite, felsic granulite, felsic amphibolite gneiss, granite-granodiorite, and mica-quartz schist with Vp of 6.35-6.45 km/s, Vs of 3.70-3.75 km/s, and sigma of 0.24; (4) lower crustal rocks most likely consist of granulite- rather than amphibolite-facies rocks with Vp of 6.60-6.80 km/s, Vs of 3.85-3.92 km/s, sigma of 0.24-0.25, and anisotropy of less than 3%; (4) depth to the Moho varies irregularly between 30.5 and 33.5. Interpretation of these results suggests that (1) Cenozoic extension of the Ruby Mountains and adjacent basins began by late Eocene-early Oligocene; (2) depth to Moho does not reflect local surface relief on the eastern flank of the Ruby Mountains and adjacent basin; (3) fluid-filled fractures and mafic large-scale underplating are unlikely in the lower crust; (4) the present seismic velocities of highly extended core complex crust and normally extended Basin and Range crust are similar; and (5) orientations of fast shear waves near the surface and in the upper crust are parallel to sub-parallel to the regional maximum horizontal compressive stress in the Nevada part of the Basin and Range province.

Satarugsa, Peangta

101

Erratum: First Results from the Wide Angle Camera of the ROSETTA Mission [Mem.SAIt Suppl. 6, 28-33 (2005)  

NASA Astrophysics Data System (ADS)

The authors acknowledge that the paper fails to convey the correct information about the respective contributions and roles of the partners of the OSIRIS consortium. In particular, the hardware contributions of the Max-Planck Institut für Sonnensystemforschung, MPS, (Katlenburg Lindau, Germany, formerly MPAe), of the Instituto de Astrofisica de Andalucia (Granada, Spain), of the Department of Astronomy and Space Physics of Uppsala University (DASP), of ESA Research and Scientific Support Department (ESA/RSSD) to the Wide Angle Camera has not been mentioned or incorrectly expounded. The overall responsibility (PI ship) of MPS (MPAe) for OSIRIS and hence for the Wide Angle Camera is not correctly mentioned either. The correct information is given in the paper by Keller et al. (2006, Space Science Review, in press). The authors take this opportunity to acknowledge that the activity of the Italian team has been partly supported by the Italian Space Agency ASI through a contract to CISAS.

Barbieri, C.; Fornasier, S.; Bertini, I.; Angrilli, F.; Bianchini, G. A.; Debei, S.; de Cecco, M.; Parzianello, G.; Zaccariotto, M.; da Deppo, V.; Naletto, G.

102

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

103

Wide angle X-ray scattering (WAXS) study of "two-line" ferrihydrite structure: Effect of arsenate sorption and counterion variation and comparison with EXAFS results  

USGS Publications Warehouse

Wide angle X-ray scattering (WAXS) measurements have been made on a suite of "two-line" ferrihydrite (FHY2) samples containing varying amounts of coprecipitated arsenate. Samples prepared at pH 8 with counter ions chloride, nitrate, and a mixture of both also were examined. The raw WAXS scattering functions show that "two-line" ferrihydrite actually has a large number of non-Bragg (i.e., diffuse scattering) maxima up to our observation limit of 16 A??-1. The type of counter ion used during synthesis produces no significant change in this function. In unarsenated samples, Radial Distribution Functions (RDFs) produced from the scattering functions show a well-defined Fe-O peak at 2.02 A?? in excellent agreement with the mean distance of 2.01 A?? from extended X-ray absorption fine structure (EXAFS) analysis. The area under the Fe-O peak is consistent with only octahedral oxygen coordination about iron, and an iron coordination about oxygen of 2.2, in agreement with the EXAFS results, the sample composition, and XANES measurements. The second peak observed in the RDFs is clearly divided into two populations of correlations, at 3.07 and 3.52 A??, respectively. These distances are close to the EXAFS-derived Fe-Fe subshell distances of 3.02-3.05 and 3.43-3.46 A??, respectively, though this is misleading as the RDF peaks also include contributions from O-Fe and O-O correlations. Simulated RDFs of the FeOOH polymorphs indicate how the observed RDF structure relates to the EXAFS pair-correlation function, and allow comparisons with an ordered ferrihydrite structure. The effect of increasing arsenate content is dramatic, as the RDF peaks are progressively smeared out, indicating a wider range of interatomic distances even at moderate surface coverages, and a loss of longer range correlations. At an As/Fe ratio of 0.68, the surface saturation level of arsenate, the RDF shows little order beyond what would be expected from small pieces of dioctahedral Fe oxyhydroxyl chains or small "sheet" units. Analysis of the first RDF peak yields components due to As-O and Fe-O correlations. As the As-O component at 1.67 A?? increases in size, the Fe-O component decreases, reflecting a decrease in Fe coordination about the average oxygen. This reduction is consistent with a decrease in mean crystallite size as suggested by EXAFS studies. Analysis of the second RDF peak components shows the progressive decrease in Fe-Fe correlations, and the enhancement of As-Fe correlations, as arsenate level increases. Comparison of the experimental RDF from coprecipitated arsenate-saturated FHY2 with simulated RDFs of model iron oxyhydroxyl structures further constrains possible sizes and geometry for the precipitates, and is consistent with sorbed complexes of the bidentate binuclear (apical oxygen sharing) type.

Waychunas, G.A.; Fuller, C.C.; Rea, B.A.; Davis, J.A.

1996-01-01

104

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

105

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

106

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

NASA Astrophysics Data System (ADS)

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

107

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

108

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

109

Retrieving radius, concentration, optical depth, and mass of different types of aerosols from high-resolution infrared nadir spectra.  

PubMed

We present a sophisticated radiative transfer code for modeling outgoing IR radiation from planetary atmospheres and, conversely, for retrieving atmospheric properties from high-resolution nadir-observed spectra. The forward model is built around a doubling-adding routine and calculates, in a spherical refractive geometry, the outgoing radiation emitted by the Earth and the atmosphere containing one layer of aerosol. The inverse model uses an optimal estimation approach and can simultaneously retrieve atmospheric trace gases, aerosol effective radius, and concentration. It is different from existing codes, as most forward codes dealing with multiple scattering assume a plane-parallel atmosphere, and as for the retrieval, it does not rely on precalculated spectra, the use of microwindows, or two-step retrievals. The simultaneous retrieval on a broad spectral range exploits the full potential of current state-of-the-art hyperspectral IR sounders, such as AIRS and IASI, and should be particularly useful in studying major pollution events. We present five example retrievals of IASI spectra observed in the range from 800 to 1200 cm(-1) above dust, volcanic ash, sulfuric acid, ice particles, and biomass burning aerosols. PMID:20648137

Clarisse, Lieven; Hurtmans, Daniel; Prata, Alfred J; Karagulian, Federico; Clerbaux, Cathy; De Mazière, Martine; Coheur, Pierre-François

2010-07-01

110

Angles, scales and parametric renormalization  

E-print Network

We decompose renormalized Feynman rules according to the scale and angle dependence of amplitudes. We use parametric representations such that the resulting amplitudes can be studied in algebraic geometry.

Francis Brown; Dirk Kreimer

2011-12-06

111

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

112

Effects of nadir CD4 count and duration of human immunodeficiency virus infection on brain volumes in the highly active antiretroviral therapy era.  

PubMed

Cerebral atrophy is a well-described, but poorly understood complication of human immunodeficiency virus (HIV) infection. Despite reduced prevalence of HIV-associated dementia in the highly active antiretroviral therapy (HAART) era, HIV continues to affect the brains of patients with chronic infection. In this study we examine patterns of brain volume loss in HIV-infected patients on HAART, and demographic and clinical factors contributing to brain volume loss. We hypothesized that nadir CD4+ lymphocyte count, duration of HIV infection, and age would be associated with reduced cortical volumes. Volumes of cortical and subcortical regions in 69 HIV-infected neuroasymptomatic (NA) individuals and 13 with at least mild acquired immunodeficiency syndrome (AIDS) dementia complex (ADC) were measured using voxel-based morphometry. Demographic and clinical factors (age, plasma HIV RNA level, current and nadir CD4 counts, duration of infection, central nervous system [CNS] penetration of antiretroviral regimen) along with their interactions were entered into a regression model selection algorithm to determine the final models that best described regional brain volumes. Relative to NA, individuals with ADC exhibited decreased total gray matter and parietal cortex volumes and increased total ventricular volumes. Final regression models showed overall cerebral volume, including gray and white matter volume and volumes of the parietal, temporal, and frontal lobes and the hippocampus, were most strongly associated with disease history factors (nadir CD4 and duration of infection). In contrast, basal ganglia volumes were related most strongly to current disease factors, most notably plasma HIV RNA. These findings indicate that individuals with a history of chronic HIV infection with previous episodes of severely impaired immune function, as reflected by reduced nadir CD4+ lymphocyte count, may be at greatest risk for cerebral atrophy. The pattern of HIV-associated brain loss may be changing from a subcortical to a cortical disease among patients who are largely asymptomatic on HAART. PMID:20113183

Cohen, Ronald A; Harezlak, Jaroslaw; Schifitto, Giovanni; Hana, George; Clark, Uraina; Gongvatana, Assawin; Paul, Robert; Taylor, Michael; Thompson, Paul; Alger, Jeffery; Brown, Mark; Zhong, Jianhui; Campbell, Thomas; Singer, Elyse; Daar, Eric; McMahon, Deborah; Tso, Yuen; Yiannoutsos, Constantin T; Navia, Bradford

2010-02-01

113

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

114

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

115

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.

Davidson, Michael W.; Tchourioukanov, Kirill I.

2006-06-15

116

What's Your Angle?  

NSDL National Science Digital Library

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

2010-01-01

117

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

118

Angle-Resolved Photoelectron Spectrometry Studies of the Autoionization of the 2s{sup 2}2p {sup 2}P Triply Excited State of Atomic Lithium: Experimental Results and R -Matrix Calculations  

SciTech Connect

We have measured the angle-resolved energy dependence of the electrons emitted over the energy range of the triply excited 2s{sup 2}2p P{sup 2} lithium resonance using synchrotron radiation. We have also calculated the behavior of the angular distribution parameter {beta} using the R -matrix approximation. Experimental and theoretical results are in good agreement and show deep minima in the 1s2p P{sup 1,} {sup 3} ionic channels. The energy at which the minima occur does not coincide with the resonance energy, but is shifted towards higher energy. (c) 2000 The American Physical Society.

Diehl, S. [Laboratoire de Spectroscopie Atomique et Ionique, UMR 8624 du CNRS, Universite Paris-Sud, B. 350, 91405 Orsay, (France)] [Laboratoire de Spectroscopie Atomique et Ionique, UMR 8624 du CNRS, Universite Paris-Sud, B. 350, 91405 Orsay, (France); Cubaynes, D. [Laboratoire de Spectroscopie Atomique et Ionique, UMR 8624 du CNRS, Universite Paris-Sud, B. 350, 91405 Orsay, (France)] [Laboratoire de Spectroscopie Atomique et Ionique, UMR 8624 du CNRS, Universite Paris-Sud, B. 350, 91405 Orsay, (France); Zhou, H. L. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States)] [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); VoKy, L. [Observatoire de la Cote d'Azur, BP 229, 06304 Nice, (France)] [Observatoire de la Cote d'Azur, BP 229, 06304 Nice, (France); Wuilleumier, F. J. [Laboratoire de Spectroscopie Atomique et Ionique, UMR 8624 du CNRS, Universite Paris-Sud, B. 350, 91405 Orsay, (France)] [Laboratoire de Spectroscopie Atomique et Ionique, UMR 8624 du CNRS, Universite Paris-Sud, B. 350, 91405 Orsay, (France); Kennedy, E. T. [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, (Ireland)] [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, (Ireland); Bizau, J. M. [Laboratoire de Spectroscopie Atomique et Ionique, UMR 8624 du CNRS, Universite Paris-Sud, B. 350, 91405 Orsay, (France)] [Laboratoire de Spectroscopie Atomique et Ionique, UMR 8624 du CNRS, Universite Paris-Sud, B. 350, 91405 Orsay, (France); Manson, S. T. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States)] [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Morgan, T. J. [Wesleyan University, Department of Physics, Middletown, Connecticut 06459 (United States)] [Wesleyan University, Department of Physics, Middletown, Connecticut 06459 (United States); Blancard, C. [DPTA, Centre CEA-DAM, BP 12, 91680-Bruyeres-le-Chatel, (France)] (and others) [DPTA, Centre CEA-DAM, BP 12, 91680-Bruyeres-le-Chatel, (France)

2000-02-21

119

Aerosol Properties from Multi-angle Satellite Imaging  

NASA Astrophysics Data System (ADS)

The MISR instrument, flying aboard the NASA Earth Observing System's Terra satellite, is pioneering the use of multi-angle imaging to monitor aerosols globally, from space. MISR obtains nine along-track images at view angles ranging from +70o through nadir to -70o, in each of four wavelengths, near-simultaneously. The instrument systematically covers air-mass-factors between one and three, and in mid-latitudes, samples scattering angles extending from about 60o to 160o. These data contain information about particle size distribution, shape, composition, and amount. Large air-mass-factors provide sensitivity to optical depth even for very thin hazes. Provided the aerosol optical depth is of order 0.15 or larger, size- and shape-discrimination makes it possible to distinguish non-spherical mineral dust and thin cirrus from spherical pollution particles over dark water, and to obtain information about the single scattering albedo as well as the size distribution of pollution components. If discrete features are visible in aerosol plumes, the height of the aerosol itself is obtained via stereo-matching. Such information is of value for identifying aerosol sources and sinks, for assessing the direct radiative impact of aerosols on global climate, and for aerosol transport model validation. Having constraints on aerosol micro-physical properties also improves the accuracy of optical depth retrievals. This work is performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Kahn, R. A.; Martonchik, J. V.; Diner, D. J.; Kalashnikova, O.

2004-05-01

120

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.

121

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

122

Wide Angle Imaging Lidar (WAIL): Theory of Operation and Results from Cross-Platform Validation at the ARM Southern Great Plains Site  

NASA Astrophysics Data System (ADS)

WAIL was designed to determine physical and geometrical characteristics of optically thick clouds using the off-beam component of the lidar return that can be accurately modeled within the 3D photon diffusion approximation. The theory shows that the WAIL signal depends not only on the cloud optical characteristics (phase function, extinction and scattering coefficients) but also on the outer thickness of the cloud layer. This makes it possible to estimate the mean optical and geometrical thicknesses of the cloud. The comparison with Monte Carlo simulation demonstrates the high accuracy of the diffusion approximation for moderately to very dense clouds. During operation WAIL is able to collect a complete data set from a cloud every few minutes, with averaging over horizontal scale of a kilometer or so. In order to validate WAIL's ability to deliver cloud properties, the LANL instrument was deployed as a part of the THickness from Off-beam Returns (THOR) validation IOP. The goal was to probe clouds above the SGP CART site at night in March 2002 from below (WAIL and ARM instruments) and from NASA's P3 aircraft (carrying THOR, the GSFC counterpart of WAIL) flying above the clouds. The permanent cloud instruments we used to compare with the results obtained from WAIL were ARM's laser ceilometer, micro-pulse lidar (MPL), millimeter-wavelength cloud radar (MMCR), and micro-wave radiometer (MWR). The comparison shows that, in spite of an unusually low cloud ceiling, an unfavorable observation condition for WAIL's present configuration, cloud properties obtained from the new instrument are in good agreement with their counterparts obtained by other instruments. So WAIL can duplicate, at least for single-layer clouds, the cloud products of the MWR and MMCR together. But WAIL does this with green laser light, which is far more representative than microwaves of photon transport processes at work in the climate system.

Polonsky, I. N.; Davis, A. B.; Love, S. P.

2004-05-01

123

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

124

A novel angle-tuned thin film filter with low angle sensitivity  

NASA Astrophysics Data System (ADS)

An angle-tuned thin film narrowband filter is widely used in the dense wavelength division multiplexing (DWDM) system. With increase of incident angle of the thin film filter, the central wavelengths of both S-polarization and P-polarization will separate obviously and shift to short wavelength much faster, which will cause serious polarization sensitivity and angle sensitivity. In conventional angle-tuned thin film filters, the research works usually focus on the polarization sensitivity. However, their angle sensitivity is very high because the effective refractive indexes of their spacer are very low. Their precision of the angle controlling system is very rigorous (less than 0.005°) and their incident angles are usually less than 20°, which will limit their wavelength tuning range. In the present paper, we propose and fabricate a novel 100 GHz angle-tuned thin film filter stack with low angle sensitivity which uses the high refractive index material ? -Si as the spacer and its incident angle can be expanded to 32°. Using the polarization beam-splitters and the half wave plates, this angle-tuned thin film filter can also eliminate the polarization sensitivity. The simulation results and the experiments show that the angle-tuned thin film filter with low angle sensitivity has a effective tuning range of 40 nm, which can cover the whole C-band and its precision of the angle control is relatively easy (more than 0.05°).

Yu, Kan; Liu, Yuanyuan; Yin, Juanjuan; Bao, Jiaqi

2015-05-01

125

Solidifying the solid angle.  

PubMed

This paper evaluates the position of the solid angle in its application to modeling in electrocardiology. Particular attention is paid to the use of the solid angle for linking cardiac electric activity to the potentials observed on the body surface. In this application, the solid angle is a dominant factor in the expression of the sources during depolarization known as the uniform double layer. In the related equivalent double layer model, the contributions of the elementary sources are also expressed in terms of solid angles, their strength not being uniform. A recently developed theory allows the equivalent double layer to be applied to both depolarization and repolarization. PMID:12539116

van Oosterom, A

2002-01-01

126

DIP ANGLE MEASURING DEVICE  

E-print Network

tude of the angle between the true horizon and the visible horizon known as the angle .... chred within the bearing by a support member 38 which is screwed onto the ... and the bearing. 55 to prevent a metal to metal contact, and a steel spring.

Boris J. Gavrisheff

127

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

128

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

129

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

130

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

131

Analysis of View Angle Used in Speechreading Training of Sentences.  

ERIC Educational Resources Information Center

This study examined the effects of speechreading sentence perception across three speaker viewing angles: front view, quarter view, and side view. The performance of a female adult with postlingual hearing loss was measured at each angle. Results indicated that the side view angle was the most effective, though performance at the other angles was…

Bauman, Sara L.; Hambrecht, Georgia

1995-01-01

132

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,

133

Pre-launch characterization of aqua MODIS scan mirror response versus scan angle for thermal emissive bands  

NASA Astrophysics Data System (ADS)

The double-sided paddle wheel scan mirror is the key optical component of the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the NASA EOS Terra and Aqua satellites. At a constant rotating speed, the scan mirror continuously reflects the Earth's top-of-atmosphere radiances through the instrument nadir aperture door and onto four focal plane assemblies (FPA), which consist of 36 spectral bands. Of those 36 bands, 16 are thermal emissive bands (TEB) with wavelengths ranging from 3.7 to 14.4?m. While this cross-track scanning system provides the Earth scene observations over a range of +/-55° viewing angles from the nadir, the on-orbit calibration for TEB is performed by an On-Board Calibrator Blackbody (OBC BB) at a fixed viewing angle. The response versus scan angle (RVS) of the scan mirror is sensitive to the MODIS radiometric calibration. This paper describes how the pre-launch TEB RVS of the Aqua MODIS was characterized at the instrument system level by using ground support equipment, a Blackbody Calibration Source (BCS). The RVS test setup, test procedure, data analysis, derivation of RVS, and the fitting uncertainty are discussed in the paper. A separate paper that gives similar RVS analysis for the MODIS Reflective Solar Bands (RSB) is presented in this proceeding.

Chiang, Kwo-Fu; Xiong, Xiaoxiong

2007-09-01

134

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

135

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

136

'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

137

High angle of attack hypersonic aerodynamics  

NASA Technical Reports Server (NTRS)

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

Harloff, Gary J.

1987-01-01

138

Pitch Angle Survey of GOODS Spiral Galaxies  

NASA Astrophysics Data System (ADS)

This research looks at how the pitch angles of galaxies change over scales of cosmic time. We measure the pitch angle, or tightness of spiral winding, using a new code, Spirality. We then compare the results to those obtained from established software, 2DFFT (2 Dimensional Fast Fourier Transform). We investigate any correlation between pitch angle and redshift, or distance from Earth. Previous research indicates that the pitch angle of a galaxy correlates with its central bulge mass and the mass of its central black hole. Thus any evolution in the distribution of pitch angles could ultimately prove to be indicative of evolution in the supermassive black hole mass function. Galaxies from the Hubble GOODS (Great Observatories Origins Deep Survey) North and South were measured. We found that there was strong agreement between Spirality and 2DFFT measurements. Spirality measured the pitch angle of the GOODS galaxies with a lower error than 2DFFT on average. With both software a correlation between pitch angle and redshift was found. Spirality observed a 6.150 increase in pitch per unit redshift. The increase in pitch angle with redshift suggests that in the past galaxies had higher pitch angles, which could be indicative of lower central black hole masses (or, more directly, central bulge masses).

Boe, Benjamin; Kennefick, Daniel; Arkansas Galaxy Evolution Survey, Arkansas Center for Space; Planetary Sciences

2015-01-01

139

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

140

Large angle spin-echo imaging.  

PubMed

A study was undertaken to assess the use of excitation flip angles greater than 90 degrees for T1 weighted spin-echo (SE) imaging with a single 180 degrees refocusing pulse and short TR values. Theoretical predictions of signal intensity for SE images with excitation pulse angles of 90-180 degrees were calculated based on the Bloch equations and then measured experimentally from MR images of MnCl2 phantoms of various concentrations. Liver signal-to-noise ratios (SNR) and liver-spleen contrast-to-noise ratios (CNR) were measured from breathhold MR images of the upper abdomen in 16 patients using 90 and 110 degrees excitation flip angles. The theoretical predictions showed significant improvements in SNR with excitation flip angles > 90 degrees, which were more pronounced at small TR values. The phantom studies showed reasonably good agreement with the theoretical predictions in correlating the excitation pulse angle with signal intensity. In the human imaging studies, the 110 degrees excitation pulse angle resulted in a 7.4% (p < .01) increase in liver SNR and an 8.2% (p = .2) increase in liver-spleen CNR compared to the 90 degrees pulse angle at TR = 275 ms. Increased signal intensity resulting from the use of large flip angle excitation pulses with a single echo SE pulse sequence was predicted and confirmed experimentally in phantoms and humans. PMID:7898278

DiIorio, G; Brown, J J; Borrello, J A; Perman, W H; Shu, H H

1995-01-01

141

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

142

Taxicab Angles and Trigonometry  

E-print Network

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.

Thompson, Kevin

2011-01-01

143

Casting and Angling.  

ERIC Educational Resources Information Center

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

Smith, Julian W.

144

Reliable measurement of the receding contact angle.  

PubMed

Surface wettability is usually evaluated by the contact angle between the perimeter of a water drop and the surface. However, this single measurement is not enough for proper characterization, and the so-called advancing and receding contact angles also need to be measured. Measuring the receding contact angle can be challenging, especially for extremely hydrophobic surfaces. We demonstrate a reliable procedure by using the common needle-in-the-sessile-drop method. Generally, the contact line movement needs to be followed, and true receding movement has to be distinguished from "pseudo-movement" occurring before the receding angle is reached. Depending on the contact angle hysteresis, the initial size of the drop may need to be surprisingly large to achieve a reliable result. Although our motivation for this work was the characterization of superhydrophobic surfaces, we also show that this method works universally ranging from hydrophilic to superhydrophobic surfaces. PMID:23451825

Korhonen, Juuso T; Huhtamäki, Tommi; Ikkala, Olli; Ras, Robin H A

2013-03-26

145

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

146

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

147

Ejs Brewsterâs Angle Model  

NSDL National Science Digital Library

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

Aguirregabiria, Juan

2008-08-20

148

Trigger Angle Targeting for Orbital Rendezvous  

NASA Astrophysics Data System (ADS)

Orbital rendezvous missions often have a co-elliptic approach phase where a chaser vehicle approaches an object with a near-constant relative altitude and relative velocity. A well known orbital rendezvous technique is to trigger the Terminal Phase Initiation (TPI) maneuver when the apparent elevation of the target reaches some nominal angle. The best elevation trigger angle on which to initiate the final transfer maneuver must balance favorable performance characteristics and desirable operational simplicity. A detailed analysis is given deriving the best trigger angles and showing how these results correlate to past missions and how they could potentially influence future ones.

Woffinden, David C.; Ben Rose, M.; Geller, David K.

2008-12-01

149

40. CENTRAL PAVILION OF WEST FACADESLIGHTLY ANGLED, FRONTAL, NORMAL ANGLE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

40. CENTRAL PAVILION OF WEST FACADE--SLIGHTLY ANGLED, FRONTAL, NORMAL ANGLE Copy photograph of photogrammetric plate LC-HABS-FS13-B-1974-839R. - St. Mary's Seminary, 600 North Paca Street, Baltimore, Independent City, MD

150

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

151

The 30-degree angle revisited.  

PubMed

The standard surgical ellipse, with 30 degrees apical angles and a length-to-width ratio of 2 or 3 to 1, works optimally on a flat surface. The same pattern, when used for excisions on strongly convex or concave surfaces, leads to distortions which may require significant revisions. The reason for these discrepancies is explainable by the mathematical differences between flat Euclidian geometry and curved non-Euclidian geometry. Understanding these basic mathematical principles as applied to cutaneous surgery should lead to better preoperative planning, fewer intraoperative surprises, and more pleasing results. PMID:16243133

Klapper, Mitchell

2005-11-01

152

Large bistatic angle clutter depolarization study  

Microsoft Academic Search

A bistatic radar test bed has recently been developed to measure the depolarization behavior of clutter at large bistatic angles in Eastern Massachusetts. Results presented in this paper describe the co- and cross-polarized S-Band NRCS for low resolution (300m by 300m) forested clutter cells viewed at low grazing angles. We also describe the variation in mean scattered power versus linear

D. J. McLaughlin; E. Boltniew; J. Barclay; R. S. Raghavan; M. J. Sowa

1994-01-01

153

Angle only tracking with particle flow filters  

NASA Astrophysics Data System (ADS)

We show the results of numerical experiments for tracking ballistic missiles using only angle measurements. We compare the performance of an extended Kalman filter with a new nonlinear filter using particle flow to compute Bayes' rule. For certain difficult geometries, the particle flow filter is an order of magnitude more accurate than the EKF. Angle only tracking is of interest in several different sensors; for example, passive optics and radars in which range and Doppler data are spoiled by jamming.

Daum, Fred; Huang, Jim

2011-09-01

154

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

155

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

156

The costovertebral angle.  

PubMed

Because the anatomy of the costovertebral angle is complex and often unfamiliar to the operating thoracic surgeon, surgical procedures performed in that area must be performed by a surgical team rather than by individual surgeons, and such a team usually includes either an orthopedic surgeon or a neurosurgeon. This is the case, for example, of Pancoast's tumors invading the roots of the brachial plexus or the spine itself where the help of an orthopedic surgeon is invaluable not only to achieve a complete resection but also to prevent catastrophic complications. PMID:18271164

Vallières, Eric

2007-11-01

157

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

158

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

159

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

160

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

161

Wide angle reflections in OBC seismic physical model experiment  

NASA Astrophysics Data System (ADS)

Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention. In this paper, we discuss ocean bottom cable (OBC) seismic wide angle reflections on the basis of a layered model experiment. Some experiment results don't support theoretical conclusions. The main experimental conclusions are: 1. Wide angle reflection energies are stronger than non-wide-angle reflections (up to twice as strong) but there is a big difference between observations and theoretical calculations that suggest the wide angle reflection energies are 15 times the nonwide-angle reflection energy. The reflection energy increases gradually rather than sharply as the theoretical calculations suggest. 2. The reflection events remain hyperbolic when the offset increases. 3. Wide angle reflection dominant frequency is about 20-30% less than nonwide-angle reflections and decreases as the offset increases. The non-wide-angle reflection dominant frequency shows no obvious variation for small offsets. 4. There is no wave shape mutation or polarity reversal near the critical angle. 5. The reflection event group features are the same for both cases of incidence angle greater and less than the critical angle. 6. Direct arrivals, multiples, and water bottom refractions influence the wide angle reflections of the sea floor.

Yang, Zheng-Hua; Huang, Yi-Jian; Wu, Yong-Xin

2012-06-01

162

Inlets for high angles of attack  

NASA Technical Reports Server (NTRS)

Different inlet designs for high angle of attack STOL and VTOL applications were tested in a subsonic wind tunnel. Three removable entry lips having contraction ratios of 1.30, 1.34 and 1.38 were tested with a single diffuser. The internal contour of each entry lip was an ellipse with a major to minor axis of 2.0. Each lip and diffuser assembly was tested to determine its tolerance to angle of attack, first with a conventional centerbody and then with an extended centerbody. Results indicate that a large improvement in separation angle (determined as a function of lip contraction ratio and inlet flow) was obtained for the extended centerbody for all contraction ratios. Improved inlet tolerance to angle of attack was obtained by reducing the adverse pressure gradient downstream of the throat.

Miller, B. A.

1976-01-01

163

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

164

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

165

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

166

Sun angle calculator  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

167

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

168

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

169

The SPARC Data Initiative: Comparison of upper troposphere/lower stratosphere ozone climatologies from limb-viewing instruments and the nadir-viewing Tropospheric Emission Spectrometer  

NASA Astrophysics Data System (ADS)

present the first comprehensive intercomparison of currently available satellite ozone climatologies in the upper troposphere/lower stratosphere (UTLS) (300-70 hPa) as part of the Stratosphere-troposphere Processes and their Role in Climate (SPARC) Data Initiative. The Tropospheric Emission Spectrometer (TES) instrument is the only nadir-viewing instrument in this initiative, as well as the only instrument with a focus on tropospheric composition. We apply the TES observational operator to ozone climatologies from the more highly vertically resolved limb-viewing instruments. This minimizes the impact of differences in vertical resolution among the instruments and allows identification of systematic differences in the large-scale structure and variability of UTLS ozone. We find that the climatologies from most of the limb-viewing instruments show positive differences (ranging from 5 to 75%) with respect to TES in the tropical UTLS, and comparison to a "zonal mean" ozonesonde climatology indicates that these differences likely represent a positive bias for p ? 100 hPa. In the extratropics, there is good agreement among the climatologies regarding the timing and magnitude of the ozone seasonal cycle (differences in the peak-to-peak amplitude of <15%) when the TES observational operator is applied, as well as very consistent midlatitude interannual variability. The discrepancies in ozone temporal variability are larger in the tropics, with differences between the data sets of up to 55% in the seasonal cycle amplitude. However, the differences among the climatologies are everywhere much smaller than the range produced by current chemistry-climate models, indicating that the multiple-instrument ensemble is useful for quantitatively evaluating these models.

Neu, J. L.; Hegglin, M. I.; Tegtmeier, S.; Bourassa, A.; Degenstein, D.; Froidevaux, L.; Fuller, R.; Funke, B.; Gille, J.; Jones, A.; Rozanov, A.; Toohey, M.; Clarmann, T.; Walker, K. A.; Worden, J. R.

2014-06-01

170

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

171

Mechanisms in open-angle glaucoma.  

PubMed

One hundred and nineteen eyes from 68 patients with open-angle glaucoma were provoked by means of a pilocarpine phenylephrine provocative test. In 22% the response was the same as that seen in normal eyes. In 78% the response was the same as that seen in contralateral eyes at risk to the development of closed-angle glaucoma, which do not develop a positive provocative test. The 68 patients were randomised and 34 submitted to a "dummy" provocative test. No significant change in pressure or outflow occurred. Fifty-two of the 93 eyes with an abnormal provocative test were selected for a peripheral iridectomy and reprovoked at least 6 months after operation. The results were significantly different from those obtained before operation. It was concluded that partial-angle closure could be demonstrated in some eyes with apparent open-angle glaucoma. The mechanisms involved in the production of partial-angle closure in eyes with apparent open-angle glaucoma are discussed. PMID:656353

Mapstone, R

1978-05-01

172

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

173

A small-angle scatterometer  

Microsoft Academic Search

The design, analysis, and performance of a small-angle scatterometer are presented. A dye-cell Gaussian apodized aperture is utilized to reduce the small-angle diffraction background, so that the system scatter becomes the dominant noise in the instrument beam profile. The geometrical aberrations are graphically shown to have no significant effect on the higher-order diffraction rings of the beam profile. Small-angle scattered

Steven J. Wein; William L. Wolfe

1989-01-01

174

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...

175

Solar cell angle of incidence corrections  

NASA Astrophysics Data System (ADS)

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.

1995-10-01

176

Large bistatic angle clutter depolarization study  

NASA Astrophysics Data System (ADS)

A bistatic radar test bed has recently been developed to measure the depolarization behavior of clutter at large bistatic angles in Eastern Massachusetts. Results presented in this paper describe the co- and cross-polarized S-Band NRCS for low resolution (300m by 300m) forested clutter cells viewed at low grazing angles. We also describe the variation in mean scattered power versus linear receiver antenna orientation angle for both vertical and horizontal transmitted polarizations. Measurements of a 20 km by 20 km region of rolling hills show that vertical copolarized NRCS exceeds horizontal copolarized NRCS by an average of 8 dB over a range of bistatic angles from 100 degrees to 160 degrees. The average polarization ratio is minus 12 dB for vertical transmitter polarization and minus 5 dB for horizontal transmitter polarization. For both transmitter polarizations and variable linear receiver antenna polarization, maximum scatter power was observed when transmitter and receiver antennas were copolarized while minimum received power was observed when the antennas were crosspolarized. Power fluctuation statistical distributions are approximately exponential for all linear receiver antenna polarization angles.

McLaughlin, D. J.; Boltniew, E.; Barclay, J.; Raghavan, R. S.; Sowa, M. J.

1994-07-01

177

Geometric structures on moment-angle manifolds  

NASA Astrophysics Data System (ADS)

A moment-angle complex \\mathscr{Z}_{\\mathscr{K}} is a cell complex with a torus action constructed from a finite simplicial complex {\\mathscr{K}}. When this construction is applied to a triangulated sphere {\\mathscr{K}} or, in particular, to the boundary of a simplicial polytope, the result is a manifold. Moment-angle manifolds and complexes are central objects in toric topology, and currently are gaining much interest in homotopy theory and complex and symplectic geometry. The geometric aspects of the theory of moment-angle complexes are the main theme of this survey. Constructions of non-Kähler complex-analytic structures on moment-angle manifolds corresponding to polytopes and complete simplicial fans are reviewed, and invariants of these structures such as the Hodge numbers and Dolbeault cohomology rings are described. Symplectic and Lagrangian aspects of the theory are also of considerable interest. Moment-angle manifolds appear as level sets for quadratic Hamiltonians of torus actions, and can be used to construct new families of Hamiltonian-minimal Lagrangian submanifolds in a complex space, complex projective space, or toric varieties. Bibliography: 59 titles.

Panov, T. E.

2013-06-01

178

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

179

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

180

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

181

Comparison of gonial angle determination from cephalograms and orthopantomogram  

PubMed Central

Introduction: Gonial angle is an important parameter of the craniofacial complex giving an indication about the vertical parameters and symmetry of the facial skeleton. Both orthopantomogram (OPG) and lateral cephalograms can be used for the measurement of gonial angle. Because of the superimpositions seen on lateral cephalograms, reliable measurement of the gonial angle becomes difficult. The aim of the present study is to check the possible application and reliability of OPG for gonial angle determination by clarifying whether there is any significant difference between the determination of gonial angle from OPG and cephalogram. Materials and Methods: Gonial angle measurements were made on lateral cephalograms and orthopantomograms of 98 patients - 44 males (mean age 25.9 years) and 54 females (mean age 21.3 years), and compared using Statistical Package for Social Sciences. Results: One-way analysis of variance demonstrated no significant differences between the values of gonial angles determined by lateral cephalogram and panoramic radiography. Pearson correlation showed a high correlation between cephalometric and OPG gonial angle value. Conclusion: Panoramic radiography can be used to determine the gonial angle as accurately as a lateral cephalogram. For determination of the gonial angle, an OPG may be a better choice than a lateral cephalogram as there are no interferences due to superimposed images of anatomical structures as in a lateral cephalogram. Thus, the present study substantiates the possibility of enhancing the clinical versatility of the panoramic radiograph, which is an indispensable tool for dental diagnosis. PMID:25565740

Bhullar, Mandeep Kaur; Uppal, Amandeep Singh; Kochhar, Gulsheen Kaur; Chachra, Sanjay; Kochhar, Anuraj Singh

2014-01-01

182

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

183

Compression failure of angle-ply laminates  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

184

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

185

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.

Integrated Teaching And Learning Program

186

Capillary torque in a liquid bridge between two angled filaments  

NASA Astrophysics Data System (ADS)

Capillary torque is induced when a liquid bridge forms between two angle-positioned filaments. This paper aims to study the dependency of such capillary torque upon the filament orientation angle, filament spacing, contact angle, and liquid volume through detailed numerical simulation using a surface finite element scheme. Numerical results show that for hydrophilic liquid with contact angle below 90° and at given liquid volume as well as filament spacing, the surface energy of the system grows nonlinearly with increasing filament orientation angle from 0° (parallel filaments) to 90° (cross-positioned filaments). Accordingly, the capillary torque induced by the distorted liquid bridge increases from a torque-free state at 0° to the peak value and then decreases to the second torque-free state at 90°. At fixed filament orientation angle, the capillary torque grows with the liquid volume while decreases rapidly with increasing either contact angle or filament spacing. The peak value of capillary torque depends upon both the geometries and wetting property of the liquid bridge-filament system. A family of characteristic curves in terms of capillary torque with the filament orientation angle is determined at varying volume of liquid bridge, filament spacing ratio, and contact angle. The results and concepts developed in work are applicable for the study of wetting and spreading of liquids in fiber networks, microfluidics-based microstructural assembly, biological cell operation, etc.

Bedarkar, Amol; Wu, Xiang-Fa

2009-12-01

187

Analyzing the installation angle error of a SAW torque sensor  

NASA Astrophysics Data System (ADS)

When a torque is applied to a shaft, normal strain oriented at ±45° direction to the shaft axis is at its maximum, which requires two one-port SAW resonators to be bonded to the shaft at ±45° to the shaft axis. In order to make the SAW torque sensitivity high enough, the installation angle error of two SAW resonators must be confined within ±5° according to our design requirement. However, there are few studies devoted to the installation angle analysis of a SAW torque sensor presently and the angle error was usually obtained by a manual method. Hence, we propose an approximation method to analyze the angle error. First, according to the sensitive mechanism of the SAW device to torque, the SAW torque sensitivity is deduced based on the linear piezoelectric constitutive equation and the perturbation theory. Then, when a torque is applied to the tested shaft, the stress condition of two SAW resonators mounted with an angle deviating from ±45° to the shaft axis, is analyzed. The angle error is obtained by means of the torque sensitivities of two orthogonal SAW resonators. Finally, the torque measurement system is constructed and the loading and unloading experiments are performed twice. The torque sensitivities of two SAW resonators are obtained by applying average and least square method to the experimental results. Based on the derived angle error estimation function, the angle error is estimated about 3.447°, which is close to the actual angle error 2.915°. The difference between the estimated angle and the actual angle is discussed. The validity of the proposed angle error analysis method is testified to by the experimental results.

Fan, Yanping; Ji, Xiaojun; Cai, Ping

2014-09-01

188

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

189

Moment-angle manifolds and complexes. Lecture notes KAIST'2010  

Microsoft Academic Search

These are notes of the lectures given during the Toric Topology Workshop at the Korea Advanced Institute of Science and Technology in February 2010. We describe several approaches to moment-angle manifolds and complexes, including the intersections of quadrics, complements of subspace arrangements and level sets of moment maps. We overview the known results on the topology of moment-angle complexes, including

Taras Panov

2010-01-01

190

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

191

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

192

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

193

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

194

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

195

Measurement of the CKM angle \\(?\\) at LHCb  

E-print Network

In this proceeding I present the latest result by the LHCb collaboration in determining the CKM angle $\\gamma$ ($(73^{+9}_{-10})^{\\circ}$). The result is determined by combining several $B \\to Dh$ analyses, and the latest results from the decay time dependent $B_{s} \\to D_{s}K$ analysis. A few other decay channels interesting for determination of $\\gamma$ in the future is also discussed. These results were presented earlier as a poster at the 50 years of CP violation conference, London, UK.

Suvayu Ali; on the behalf of the LHCb Collaboration

2014-10-31

196

Directed Polymers with Constrained Winding Angle  

E-print Network

In this article we study from a non-perturbative point of view the entanglement of two directed polymers subjected to repulsive interactions given by a Dirac $\\delta-$function potential. An exact formula of the so-called second moment of the winding angle is derived. This result is used to provide a thorough analysis of entanglement phenomena in the classical system of two polymers subjected to repulsive interactions and related problems. No approximation is made in treating the constraint on the winding angle and the repulsive forces. In particular, we investigate how repulsive forces influence the entanglement degree of the two-polymer system. In the limit of ideal polymers, in which the interactions are switched off, we show that our results are in agreement with those of previous works.

Franco Ferrari; Vakhtang G. Rostiashvili; Thomas A. Vilgis

2004-12-16

197

Monte Carlo simulations for High Zenigh Angle  

NASA Astrophysics Data System (ADS)

With the advent of new generation Imaging Atmospheric Cherenkov Telescopes (IACTs), with improved sensitivity, it will be mandatory to extend observation to High Zenith Angles (HZA). This will allow us to extend by a large factor the observation time as well as the statistics for any gamma-ray source. Here we present some results obtained for several zenith angles and for different energies of the primary particle, obtained with a modification in the CORSIKA code, which will allow us to simulate and study the behavior of atmospheric Extensive Air Showers at HZA. In order to obtain more realistic results, the effect of the atmospheric attenuation, including Rayleigh scattering, Mie scattering and Ozone absorption, is included as well. .

Ibarra, A.; González, J. C.; Cortina, J.; Barrio, J. A.; Fonseca, V.

2000-06-01

198

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

199

Directed polymers with constrained winding angle.  

PubMed

In this paper we study from a nonperturbative point of view the entanglement of two directed polymers subjected to repulsive interactions given by a Dirac delta-function potential. An exact formula of the so-called second moment of the winding angle is derived. This result is used to provide a thorough analysis of entanglement phenomena in the classical system of two polymers subjected to repulsive interactions and related problems. No approximation is made in treating the constraint on the winding angle and the repulsive forces. In particular, we investigate how repulsive forces influence the entanglement degree of the two-polymer system. In the limit of ideal polymers, in which the interactions are switched off, we show that our results are in agreement with those of previous works. PMID:16089756

Ferrari, Franco; Rostiashvili, Vakhtang G; Vilgis, Thomas A

2005-06-01

200

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

201

Measurement of ?( ?? ?? ?)\\/ ?( ?? ??) and the pseudoscalar mixing angle  

Microsoft Academic Search

We have measured the radiative decays ????, ????? selecting ?+????? final state in a sample of ?5×107?-mesons produced at the Frascati ?-factory DA?NE. We obtain ?(?????)\\/?(????)=(4.70±0.47±0.31)×10?3. From this result we derive new accurate values for the branching ratio BR(?????)=(6.10±0.61±0.43)×10?5 and the mixing angle of pseudoscalar mesons in the flavour basis ?P=(41.8+1.9?1.6)°.

A Aloisio; F Ambrosino; A Antonelli; M Antonelli; C Bacci; G Bencivenni; S Bertolucci; C Bini; C Bloise; V Bocci; F Bossi; P Branchini; S. A Bulychjov; G Cabibbo; R Caloi; P Campana; G Capon; G Carboni; M Casarsa; V Casavola; G Cataldi; F Ceradini; F Cervelli; F Cevenini; G Chiefari; P Ciambrone; S Conetti; S Dell'Agnello; A Denig; A Doria; M Dreucci; O Erriquez; A Farilla; G Felici; A Ferrari; M. L Ferrer; G Finocchiaro; C Forti; A Franceschi; P Franzini; C Gatti; P Gauzzi; S Giovannella; E Gorini; F Grancagnolo; E Graziani; S. W Han; M Incagli; L Ingrosso; W Kluge; C Kuo; V Kulikov; F Lacava; G Lanfranchi; J Lee-Franzini; D Leone; F Lu; M Martemianov; M Matsyuk; W Mei; L Merola; R Messi; S Miscetti; M Moulson; S Müller; F Murtas; M Napolitano; A Nedosekin; F Nguyen; M Palutan; L Paoluzi; E Pasqualucci; L Passalacqua; A Passeri; V Patera; E Petrolo; G Pirozzi; C Pistillo; L Pontecorvo; M Primavera; F Ruggieri; P Santangelo; E Santovetti; G Saracino; R. D Schamberger; B Sciascia; A Sciubba; F Scuri; I Sfiligoi; T Spadaro; E Spiriti; G. L Tong; L Tortora; E Valente; P Valente; B Valeriani; G Venanzoni; S Veneziano; A Ventura; Y Xu; Y Yu

2002-01-01

202

The CLAS Electromagnetic Calorimeter at Large Angles  

SciTech Connect

The study of the response of the two modules of the large-angle electromagnetic shower calorimeter (LAC) of the CLAS detector to charged and neutral particles is reported. The results agree very well with the Monte Carlo simulation. The procedures adopted for the energy and timing calibration are also discussed, proving that the module geometry allows for simple self-calibrating energy and timing algorithms.

Anghinolfi, Marco; Avagyan, Harutyun; Battaglieri, Marco; Bianchi, Nicola; Corvisiero, Pietro; De Vita, Raffaella; Golovatch, E.; Gyurjyan, Vardan; Mirazita, Marco; Mokeev, Viktor; Muccifora, Valeria; Osipenko, Mikhail; Polli, Ermanno; Ricco, Giovanni; Ripani, Marco; Ronchetti, Federico; Rossi, Patrizia; Sapunenko, Vladimir; Taiuti, Mauro

2004-09-01

203

High angle of attack: Aerodynamics  

NASA Technical Reports Server (NTRS)

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

Lamar, John E.

1992-01-01

204

Management of angle closure glaucoma  

PubMed Central

Primary angle closure glaucoma (PACG) is equally prevalent in Indian in Asian population as the primary open angle glaucoma. Eighty-six percent of people with PACG are in Asia, with approximately 48.0% in China, 23.9% in India and 14.1% in southeast Asia. To understand PACG, it is mandatory to understand its classification and type of presentation with the underlying pathophysiology. The treatment options are medical, laser and/or surgical. The present article provides an overview of PACG. PMID:21150039

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

2011-01-01

205

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

206

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

207

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

208

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

209

Paired-angle multiplicative compounding.  

PubMed

Ultrasound compounding is a method of combining multiple images from different angles in order to create a single image with improved resolution and reduced angular-dependent artifactual detail. Compounding methods traditionally calculate each pixel in the compound image as a simple functional relationship between pixel elements in the component image set. In order to achieve an even better resolution and further reduce angular-dependent artifacts, this paper investigates a new type of compounding we call paired angle multiplicative compounding (PAMC), in which compound images are produced by a summation of multiplied pairs of component images acquired at different angles. A PAMC image of a breast phantom demonstrates improved delineation ofmicrocalcifications in comparison to the mean operation. Images of the forearm are used to investigate larger angles of paired multiplication, the best improving contrast ratio (28%) and signal to noise ratio (24%) when compared to the mean method. The PAMC method is found to be similar to the MEM and median compounding operations, the largest difference being that it is better preserving contributions from normal incidence but at the expense of needing a larger angular range. PMID:18939612

Macione, James; Yang, Zhi; Fox, Martin

2008-04-01

210

High-angle gravel pack completion studies  

SciTech Connect

A two-part study was conducted to define optimum gravel pack procedures and completion design factors for high-angle wells. In the first part of the study, gravel slurries were pumped through an 1100 ft tubing string to simulate actual slurry transport conditions in high-angle wells. The tubing string had an inclination of 80/sup 0/ from vertical. Measurements were made to determine suitable viscosity and solids concentration for effective gravel transport. In the second part of the study a cased hole completion model was constructed at full scale. Gravel slurries that had satisfactory transport performance were tested for packing characteristics in the model wellbore (completion interval). Need for special completion interval geometric considerations to obtain satisfactory packs was investigated. Results of this study showed that high viscosity carrier fluids (600-700 cp) with high gravel concentrations (15 lbm/gal) provide good transport, but they are unsuitable for use in completion intervals in wells with angles of 80/sup 0/ from vertical. Satisfactory transport and improved packing were achieved with lower carrier viscosity and concentration (300-400 cp, 4 lbm/ gal). Special liner-tailpipe (washpipe) geometry considerations reported by previous investigators are required in conjunction with the optimum slurry properties defined in this study. Completion operations designed using results from this study have satisfactorily met general placement criteria. Field experience to date has been in wells with inclinations up to 70/sup 0/ from vertical.

Elson, T.D.; Darlington, R.M.; Mantooth, M.A.

1983-03-01

211

Head flexion angle while using a smartphone.  

PubMed

Repetitive or prolonged head flexion posture while using a smartphone is known as one of risk factors for pain symptoms in the neck. To quantitatively assess the amount and range of head flexion of smartphone users, head forward flexion angle was measured from 18 participants when they were conducing three common smartphone tasks (text messaging, web browsing, video watching) while sitting and standing in a laboratory setting. It was found that participants maintained head flexion of 33-45° (50th percentile angle) from vertical when using the smartphone. The head flexion angle was significantly larger (p < 0.05) for text messaging than for the other tasks, and significantly larger while sitting than while standing. Study results suggest that text messaging, which is one of the most frequently used app categories of smartphone, could be a main contributing factor to the occurrence of neck pain of heavy smartphone users. Practitioner Summary: In this laboratory study, the severity of head flexion of smartphone users was quantitatively evaluated when conducting text messaging, web browsing and video watching while sitting and standing. Study results indicate that text messaging while sitting caused the largest head flexion than that of other task conditions. PMID:25323467

Lee, Sojeong; Kang, Hwayeong; Shin, Gwanseob

2015-02-01

212

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

213

Stable Divergence Angles of a Magnetic Dipole Spiral Array  

NASA Astrophysics Data System (ADS)

An analytical model is introduced for the experiment of Douady and Couder [Phys. Rev. Lett. 68, 2098 (1992), where phyllotactic patterns appear as a dynamical result of the interaction between magnetic dipoles. The difference equation for the divergence angle (i.e. the angle between successive radial vectors) is obtained by solving the equations of motion with a second nearest neighbor (SNN) approximation. A one-dimensional map analysis as well as a comprehensive analytical proof shows that the divergence angle always converges to a single attractor regardless of the initial conditions. This attractor is approximately the Fibonacci angle(~ 138°) within variations due to a growth factor ? of the pattern. The system is proved to be stable with the SNN approximation. Further analysis with a third nearest neighbor approximation (TNN) shows extra linearly stable attractors may appear around the Lucas angle (~ 99.5°).

Fan, X. D.; Bursill, L. A.

214

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

215

Stabilization of the angle of entry of ultrasound  

SciTech Connect

Techniques for stabilizing the angle of entry of ultrasound against fluctuations of the ambient temperature and the temperature of the tested material and the contact fluid are discussed, along with the angle-beam transducer configurations for implementation of the proposed techniques. The results of tests of the newly designed transducers are given. The positive results of the experiments permit the given transducer configuration to be incorporated into a newly constructed portable laboratory for flaw detection in drill pipe.

Turko, F.I.; Karpash, O.M.; Migal, I.G.; Bazhaluk, Ya.M.

1989-02-01

216

Angle interferometer cross axis errors  

SciTech Connect

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

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

1994-01-01

217

Unilateral acute angle closure glaucoma.  

PubMed

A 52-year-old gentleman presented with 1-week history of severe right-sided headache associated with reduced vision in his right, amblyopic eye. Examination revealed raised intraocular pressure at 64 mm Hg. The anterior chamber (AC) was shallow and there was a dense cataract with no red reflex or fundal view. The contralateral eye had a deep anterior chamber with normal pressure and a clear lens. He was treated initially for acute angle closure glaucoma. The anterior chamber remained shallow and the intraocular pressure uncontrolled, despite maximum medical therapy. Owing to the absent fundal view and unilateral AC shallowing, further imaging was performed and a choroidal mass was found to be responsible for anterior displacement of the lens and shallowing of the angle. He went on to have an enucleation of the right eye, and histological examination confirmed the diagnosis of choroidal melanoma. PMID:23440984

Tan, Shi Zhuan; Sampat, Keerthika; Rasool, Sana; Nolan, Daniel

2013-01-01

218

Small angle scattering and asphaltenes  

NASA Astrophysics Data System (ADS)

Petroleum is a mixture of organic material consisting of a series of molecules with increasing molecular weight but with decreasing carbon to hydrogen ratios. This monotonic trend leads to distinctive properties of each class, cut by solvents. Asphaltenes are a class soluble in toluene but not in heptane. The importance of asphaltenes lies in their relevance to petroleum operations. Many properties of petroleum liquids are due to the interplay between asphaltenes and other co-existing components. These complex interactions impact on petroleum phases, and thus the operations. So-called petroleomics is a scheme to link the molecular structures of the most relevant components in the petroleum liquid to its overall properties, similar to the proteomics widely accepted in biological sciences. However, though the asphaltene molecular structure and compositions are relevant to the macroscopic properties of petroleum liquids, their aggregates on the colloidal length scale could be the most relevant elementary unit that dictates the properties of the petroleum mixtures. In this regard, it is legitimate to use small angle x-ray scattering (SAXS) and small angle neutron scattering (SANS) techniques to bridge the molecular structures of asphaltenes and the operational parameters that are commonly applied in the field. In this review, the linkages between asphaltene molecules and their aggregates and the asphaltene aggregates and the macroscopic properties are described. Applications of small angle x-ray and neutron scattering for characterizing asphaltene aggregates and asphaltene emulsions are also discussed.

Sheu, Eric Y.

2006-09-01

219

Gaia basic angle monitoring system  

NASA Astrophysics Data System (ADS)

The Gaia mission will create an extraordinarily precise three-dimensional map of more than one billion stars in our Galaxy. The Gaia spacecraft, 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’. This accuracy requires ultra-high stability, 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 system for this mission. The BAM measures 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 measure Optical Path Differences (OPD) as small as 1.5 picometer rms. Following a general introduction to the Gaia mission, the Payload Module (PLM) and the use of Silicon Carbide as base material, this presentation will address an overview of the challenges towards the key requirements, design, integration and testing (including space-level qualification) of the Gaia BAM.

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

2012-09-01

220

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

221

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

PubMed Central

To produce the greatest horizontal distance in a punt kick the ball must be projected at an appropriate angle. Here, we investigated the optimum projection angle that maximises the distance attained in a punt kick by a soccer goalkeeper. Two male players performed many maximum-effort kicks using projection angles of between 10° and 90°. The kicks were recorded by a video camera at 100 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity, projection angle, projection height, ball spin rate, and foot velocity at impact. The player’s optimum projection angle was calculated by substituting mathematical equations for the relationships between the projection variables into the equations for the aerodynamic flight of a soccer ball. The calculated optimum projection angles were in agreement with the player’s preferred projection angles (40° and 44°). In projectile sports even a small dependence of projection velocity on projection angle is sufficient to produce a substantial shift in the optimum projection angle away from 45°. In the punt kicks studied here, the optimum projection angle was close to 45° because the projection velocity of the ball remained almost constant across all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle and so the optimum projection angle is well below 45°. Key points The optimum projection angle that maximizes the distance of a punt kick by a soccer goalkeeper is about 45°. The optimum projection angle is close to 45° because the projection velocity of the ball is almost the same at all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the optimum projection angle is well below 45° because the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle. PMID:24149315

Linthorne, Nicholas P.; Patel, Dipesh S.

2011-01-01

222

X-29 at High Angle of Attack  

NASA Technical Reports Server (NTRS)

This photo shows the X-29 during a 1991 research flight. Smoke generators in the nose of the aircraft were used to help researchers see the behavior of the air flowing over the aircraft. The smoke here is demonstrating forebody vortex flow at a high angle of attack. Angle of attack, or high alpha, refers to the angle of an aircraft's body and wings relative to its actual flight path.. The tufts that can be seen in this photo attached to the fuselage and wings of the X-29 were also used to help researchers visualize the air flow over the plane. Two X-29 aircraft, featuring one of the most unusual designs in aviation history, flew at the Ames-Dryden Flight Research Facility (now the Dryden Flight Research Center, Edwards, California) from 1984 to 1992. The fighter-sized X-29 technology demonstrators explored several concepts and technologies including: the use of advanced composites in aircraft construction; variable-camber wing surfaces; a unique forward- swept wing and its thin supercritical airfoil; strakes; close-coupled canards; and a computerized fly-by-wire flight control system used to maintain control of the otherwise unstable aircraft. Research results showed that the configuration of forward-swept wings, coupled with movable canards, gave pilots excellent control response at angles of attack of up to 45 degrees. During its flight history, the X-29 aircraft flew 422 research missions and a total of 436 missions. Sixty of the research flights were part of the X-29 follow-on 'vortex control' phase. The forward-swept wing of the X-29 resulted in reverse airflow, toward the fuselage rather than away from it, as occurs on the usual aft-swept wing. Consequently, on the forward-swept wing, the ailerons remained unstalled at high angles of attack. This provided better airflow over the ailerons and prevented stalling (loss of lift) at high angles of attack. Introduction of composite materials in the 1970s opened a new field of aircraft construction. It also made possible the construction of the X-29's thin supercritical wing. State-of-the-art composites allowed aeroelastic tailoring which, in turn, allowed the wing some bending but limited twisting and eliminated structural divergence within the flight envelope (i.e. deformation of the wing or the wing breaking off in flight). Additionally, composite materials allowed the wing to be sufficiently rigid for safe flight without adding an unacceptable weight penalty. The X-29 project consisted of two phases plus the follow-on vortex-control phase. Phase 1 demonstrated that the forward sweep of the X-29 wings kept the wing tips unstalled at the moderate angles of attack flown in that phase (a maximum of 21 degrees). Phase I also demonstrated that the aeroelastic tailored wing prevented structural divergence of the wing within the flight envelope, and that the control laws and control-surface effectiveness were adequate to provide artificial stability for an otherwise unstable aircraft. Phase 1 further demonstrated that the X-29 configuration could fly safely and reliably, even in tight turns. During Phase 2 of the project, the X-29, flying at an angle of attack of up to 67 degrees, demonstrated much better control and maneuvering qualities than computational methods and simulation models had predicted . During 120 research flights in this phase, NASA, Air Force, and Grumman project pilots reported the X-29 aircraft had excellent control response to an angle of attack of 45 degrees and still had limited controllability at a 67-degree angle of attack. This controllability at high angles of attack can be attributed to the aircraft's unique forward-swept wing- canard design. The NASA/Air Force-designed high-gain flight control laws also contributed to the good flying qualities. During the Air Force-initiated vortex-control phase, the X-29 successfully demonstrated vortex flow control (VFC). This VFC was more effective than expected in generating yaw forces, especially in high angles of attack where the rudder is less effective. VFC was less effective in providing control when side

1991-01-01

223

Moment-angle manifolds and complexes. Lecture notes KAIST'2010  

E-print Network

These are notes of the lectures given during the Toric Topology Workshop at the Korea Advanced Institute of Science and Technology in February 2010. We describe several approaches to moment-angle manifolds and complexes, including the intersections of quadrics, complements of subspace arrangements and level sets of moment maps. We overview the known results on the topology of moment-angle complexes, including the description of their cohomology rings, as well as the homotopy and diffeomorphism types in some particular cases. We also discuss complex-analytic structures on moment-angle manifolds and methods for calculating invariants of these structures.

Panov, Taras

2010-01-01

224

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

225

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

226

Compression failure of angle-ply laminates  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

227

Wall Angle Effects on Nozzle Separation Stability  

NASA Astrophysics Data System (ADS)

The presence of asymmetric side loads due to unstable separation within over-expanded rocket nozzles is well documented. Although progress has been made in developing understanding of this phenomenon through numerical and experimental means, the causes of these side loads have yet to be fully explained. The hypothesis examined within this paper is that there is a relationship between nozzle wall angle at the point of separation, and the stability of the flow separation. This was achieved through an experimental investigation of a series of subscale over-expanded conical nozzles with half-angles of 8.3°, 10.4°, 12.6° and 14.8°. All had overall area ratios of 16:1, with separation occurring at approximately half the nozzle length (i.e. area ration of 4:1) under an overall pressure ratio of approximately 7:1 using air as the working fluid. The structure of exhaust flow was observed and analysed by use of an optimised Schlieren visualisation system, coupled with a high speed digital camera. The 12.6° and 14.8° nozzles exhaust flow were seen to be stable throughout the recorded test period of 10 seconds. However, a small number of large fluctuations in the jet angle were seen to be present within the flowfield of the 10.4° nozzle, occurring at apparently random intervals through the test period. The flowfield of the 8.3° nozzle demonstrated near continuous, large angle deviations in the jet, with flow patterns containing thickened shear layers and apparent reattachment to the wall, something not previously identified in conical nozzles. These results were used to design a truncated ideal contour with an exit angle of over 10 degrees, in order to assess the possibility of designing conventional nozzles that separate stably over a wide range of pressure ratios. These tests were successful, potentially providing a simpler, cheaper alternative to altitude compensating nozzle devices. However, more work determining the nature of the separation and its causes is required.

Aghababaie, A.; Taylor, N.

228

Angles, Scales and Parametric Renormalization  

NASA Astrophysics Data System (ADS)

We discuss the structure of renormalized Feynman rules. Regarding them as maps from the Hopf algebra of Feynman graphs to {{C}} originating from the evaluation of graphs by Feynman rules, they are elements of a group {G=Spec_{Feyn}(H)} . We study the kinematics of scale and angle-dependence to decompose G into subgroups {G_{{1-s}}} and {G_{fin}} . Using parametric representations of Feynman integrals, renormalizability and the renormalization group underlying the scale dependence of Feynman amplitudes are derived and proven in the context of algebraic geometry.

Brown, Francis; Kreimer, Dirk

2013-09-01

229

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.

230

Installation Design of Solar Panels with Seasonal Adjustment of Tilt-Angles  

Microsoft Academic Search

In this work, a mathematical procedure was developed for estimating the annual collectible radiation on solar panels with different mode of tilt-angle adjustment based on the monthly horizontal radiation. Calculation results show that, for solar panels with seasonal adjustment of tilt-angles, the optimum date of tilt-angle adjustment is 22 days from the equinoxes, and the optimum value of tilt-angle adjustment

Runsheng Tang; Xinyue Liu

2010-01-01

231

Reflective properties of randomly rough surfaces under large incidence angles.  

PubMed

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

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

2014-06-01

232

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.

2012-08-03

233

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.

234

Adaptive Control of a Vibratory Angle Measuring Gyroscope  

PubMed Central

This paper presents an adaptive control algorithm for realizing a vibratory angle measuring gyroscope so that rotation angle can be directly measured without integration of angular rate, thus eliminating the accumulation of numerical integration errors. The proposed control algorithm uses a trajectory following approach and the reference trajectory is generated by an ideal angle measuring gyroscope driven by the estimate of angular rate and the auxiliary sinusoidal input so that the persistent excitation condition is satisfied. The developed control algorithm can compensate for all types of fabrication imperfections such as coupled damping and stiffness, and mismatched stiffness and un-equal damping term in an on-line fashion. The simulation results show the feasibility and effectiveness of the developed control algorithm that is capable of directly measuring rotation angle without the integration of angular rate. PMID:22163667

Park, Sungsu

2010-01-01

235

Small-angle electron-positron scattering  

E-print Network

We consider small--angle electron--positron scattering in Quantum Electrodynamics. Leading logarithmic contributions to the cross--section are explicitly calculated to three loop. Next--to--leading terms are exactly computed to two loop. All the radiative corrections due to photons as well as pair production are taken into account. The impact of newly evaluated next-to-leading and higher order leading corrections is discussed and numerical results are explicitly given. The results obtained are generally valid for high and low energy e^+e^- colliders. At LEP and SLC these results can be used to reduce the uncertainty on the cross--section below the per mille level. PACS numbers 12.15.Lk, 12.20.--m, 12.20.Ds, 13.40.--f

Arbuzov, A B; Kuraev, E A; Lipatov, L N; Merenkov, N P; Trentadue, L G

1997-01-01

236

External measurement of dihedral right angles with cyclic optical configuration.  

PubMed

A new technique for external measurement of dihedral right angles is presented. An expanded, collimated, and linearly polarized He-Ne laser beam (632.8 nm) from a Fizeau interferometer is launched into a cyclic path optical configuration (CPOC) in which the counterpropagating p and s polarization components traverse the same optical path in opposite directions. A right-angled component (RAC), with its plane surfaces forming the right angle, is set to externally reflect the counterpropagating p and s components of the CPOC in nearly the same directions but with a lateral separation. In a plane normal to the right-angle edge of the RAC, the laterally separated collimated beams have angular separation, which is equal to twice the error in the dihedral right angle. Another CPOC setup is used to recombine the beams by reducing the lateral shear to zero. Error in right angle is calculated from the spacing of the resulting two-beam Fizeau fringes. Methods for overcoming the restriction of measurement accuracy due to beam aperture limitation and the effects of the positional tilt of the RAC have been discussed. Results of validation experiments are presented. PMID:19277094

Chatterjee, Sanjib; Kumar, Y Pavan

2009-03-10

237

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

238

Angle-dependent transmission in graphene heterojunctions  

NASA Astrophysics Data System (ADS)

We describe an experimental setup for measuring angle-dependent transmission due to Klein tunneling through quasi-ballistic graphene heterojunctions. Our devices consist of straight and angled leads, in which the barrier height is controlled by a shared gate electrode. Using a balancing technique and a differential measurement, we show how to isolate the angle-dependent contribution to the resistance from other angle-insensitive, gate-dependent, and device-dependent effects. We find that our baseline signal is dominated by mesoscopic conductance fluctuations, but that the increase in the fluctuation amplitude is due to angle-dependent transmission.

Rahman, Atikur; Guikema, Janice Wynn; Hassan, Nora M.; Markovi?, Nina

2015-01-01

239

Limbus Impact on Off-angle Iris Degradation  

SciTech Connect

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

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

2013-01-01

240

Effects of Attack Angle on Side Jet Interaction in Supersonic Flow  

NASA Astrophysics Data System (ADS)

The effects of attack angle on side jet aerodynamic interaction were experimentally investigated. Experiments were conducted by using the ISAS supersonic wind tunnel. A model used in this study is a 10deg half-angle blunt cone with a circular sonic jet injected at right angles to the body surface on the leeward side. Force and surface pressure measurements were performed as well as schlieren and oil flow visualizations. As a result, it is found that the aerodynamic interaction promotes the jet reaction force with increasing attack angle. Furthermore, the flowfields with aerodynamic interaction at high attack angles were clarified.

Kurita, Mitsuru; Okada, Takumi; Nakamura, Yoshiaki; Hongo, Motoyuki; Inatani, Yoshifumi

241

Angled Layers in Super Resolution  

NASA Technical Reports Server (NTRS)

Researchers used a special imaging technique with the panoramic camera on NASA's Mars Exploration Rover Opportunity to get as detailed a look as possible at a target region near eastern foot of 'Burns Cliff.' The intervening terrain was too difficult for driving the rover closer. The target is the boundary between two sections of layered rock. The layers in lower section (left) run at a marked angle to the layers in next higher section (right).

This view is the product of a technique called super resolution. It was generated from data acquired on sol 288 of Opportunity's mission (Nov. 14, 2004) from a position along the southeast wall of 'Endurance Crater.' Resolution slightly higher than normal for the panoramic camera was synthesized for this view by combining 17 separate images of this scene, each one 'dithered' or pointed slightly differently from the previous one. Computer manipulation of the individual images was then used to generate a new synthetic view of the scene in a process known mathematically as iterative deconvolution, but referred to informally as super resolution. Similar methods have been used to enhance the resolution of images from the Mars Pathfinder mission and the Hubble Space Telescope.

2004-01-01

242

Nanostructure surface design for broadband and angle-independent antireflection  

NASA Astrophysics Data System (ADS)

Three different antireflecting structures (ARS), namely, single-diameter nanorods, dual-diameter nanorods, and biomimetic nanotips (resembling moth-eye's submicrostructures) were compared to each other analytically for their reflectivities, using finite difference time domain calculations. Simulation results establish the biomimetic nanotips as better ARS than the others, in the visible and near-infrared wavelength zone and over a wider angle of incidence. The reflectance values in the nanotips are significantly lower compared to both types of nanorods and also the planar silicon below the Brewster angle (˜75 deg). The low antireflection translated to enhanced optical absorption in these subwavelength structures. A general antireflection design rule emerged from the simulation results.

Huang, Yi Fan; Chattopadhyay, Surojit

2013-01-01

243

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

244

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

245

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

246

Distinguishing features of shallow angle plunging jets  

NASA Astrophysics Data System (ADS)

Numerical simulations employing an algebraic volume-of-fluid methodology are used to study the air entrainment characteristics of a water jet plunging into a quiescent water pool at angles ranging from ? = 10° to ? = 90° measured from the horizontal. Our previous study of shallow angled jets [S. S. Deshpande, M. F. Trujillo, X. Wu, and G. L. Chahine, "Computational and experimental characterization of a liquid jet plunging into a quiescent pool at shallow inclination," Int. J. Heat Fluid Flow 34, 1-14 (2012)], 10.1016/j.ijheatfluidflow.2012.01.011 revealed the existence of a clearly discernible frequency of ingestion of large air cavities. This is in contrast with chaotic entrainment of small air pockets reported in the literature in case of steeper or vertically plunging jets. In the present work, the differences are addressed by first quantifying the cavity size and entrained air volumes for different impingement angles. The results support the expected trend - reduction in cavity size (D43) as ? is increased. Time histories of cavity volumes in the vicinity of the impingement region confirm the visual observations pertaining to a near-periodic ingestion of large air volumes for shallow jets (10°, 12°), and also show that such cavities are not formed for steep or vertical jets. Each large cavity (defined as Dc/Dj ? 3) exists in close association with a stagnation point flow. A local mass and momentum balance shows that the high stagnation pressure causes a radial redirection of the jet, resulting in a flow that resembles the initial impact of a jet on the pool. In fact, for these large cavities, their speed matches closely Uimpact/2, which coincides with initial cavity propagation for sufficiently high Froude numbers. Furthermore, it is shown that the approximate periodicity of air entrainment scales linearly with Froude number. This finding is confirmed by a number of simulations at ? = 12°. Qualitatively, for steeper jets, such large stagnation pressure region does not exist, and the deflection of the entire incoming jet is non-existent. In fact, for ? = 25°, 45°, 90°, the jet penetrates the pool nearly undisturbed and consequently large cavities are not formed.

Deshpande, Suraj S.; Trujillo, Mario F.

2013-08-01

247

Wide-angle energy-momentum spectroscopy.  

PubMed

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

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

2014-07-01

248

Correlation analysis of the beam angle dependence for elastography  

PubMed Central

Signal decorrelation is a major source of error in the displacements estimated using correlation techniques for elastographic imaging. Previous papers have addressed the variation in the correlation coefficient as a function of the applied compression for a finite window size and an insonification angle of zero degrees. The recent use of angular beam-steered radio-frequency echo signals for spatial angular compounding and shear strain estimation have demonstrated the need for understanding signal decorrelation artifacts for data acquired at different beam angles. In this paper, we provide both numerical and closed form theoretical solutions of the correlation between pre- and post-compression radio-frequency echo signals acquired at a specified beam angle. The expression for the correlation coefficient obtained is a function of the beam angle and the applied compression for a finite duration window. Accuracy of the theoretical results is verified using tissue-mimicking phantom experiments on a uniformly elastic phantom using beam-steered data acquisitions on a linear array transducer. The theory predicts a faster decorrelation with changes in the beam or insonification angle for longer radio-frequency echo signal segments and at deeper locations in the medium. Theoretical results provide useful information for improving angular compounding and shear strain estimation techniques for elastography. PMID:16838551

Rao, Min; Varghese, Tomy

2006-01-01

249

Wind-tunnel calibration and requirements for in-flight use of fixed hemispherical head angle-of-attack and angle-of-sideslip sensors  

NASA Technical Reports Server (NTRS)

Wind-tunnel tests were conducted with three different fixed pressure-measuring hemispherical head sensor configurations which were strut-mounted on a nose boom. The tests were performed at free-stream Mach numbers from 0.2 to 3.6. The boom-angle-of-attack range was -6 to 15 deg, and the angle-of-sideslip range was -6 to 6 deg. The test Reynolds numbers were from 3.28 million to 65.6 million per meter. The results were used to obtain angle-of-attack and angle-of-sideslip calibration curves for the configurations. Signal outputs from the hemispherical head sensor had to be specially processed to obtain accurate real-time angle-of-attack and angle-of-sideslip measurements for pilot displays or aircraft systems. Use of the fixed sensors in flight showed them to be rugged and reliable and suitable for use in a high temperature environment.

Montoya, E. J.

1973-01-01

250

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

251

Assessment of angle velocity in girls with adolescent idiopathic scoliosis  

PubMed Central

Background Although it has been demonstrated that the peak height velocity (PHV) is a predictive factor of progression in adolescent idiopathic scoliosis (AIS), little is known about the usefulness of angle progression in clinical practice. The purpose of this study was to establish a relationship between height and angle velocities, as well as to determine if peak angle velocity (PAV) occurs at the same time than PHV. Methods A retrospective study of a cohort of girls with idiopathic scoliotic curves greater than 10°. Data of 132 girls who participated in a previous retrospective study about growth in AIS were used to calculate height and angle velocities. Relationship between height and angle velocities was estimated by the use of a Linear Mixed Model. Results PHV and PAV take place simultaneously 1 year before menarche in progressive curves managed with a brace in AIS. Changes in angle velocity are influenced by changes in height growth velocity, in such a way that as from 6 months post-menarche, height growth velocity in this group of girls estimates curve progression velocity (?-coefficient -0.88, p = 0.04). Conclusion As from 6 months post-menarche, there is an inverse relationship between height velocity and curve progression in the group of AIS girls with progressive curves managed with a brace. Because height velocity is decreasing from 1 year before menarche, this finding corroborates that at the end of puberty, there is still a risk of progression in this group of girls despite bracing. The assessment of both height and angle velocity might be useful in clinical practice at the time of assessing brace effectiveness and how long bracing has to be indicated. PMID:19758424

Escalada, Ferran; Marco, Ester; Duarte, Esther; Ma Muniesa, Josep; Boza, Roser; Tejero, Marta; Cáceres, Enric

2009-01-01

252

Tracheo-bronchial angles in the human fetus – an anatomical, digital, and statistical study  

PubMed Central

Background Both the advancement of visual techniques and intensive progress in perinatal medicine result in performing airway management in the fetus and neonate affected by life-threatening malformations. This study aimed to examine the 3 tracheo-bronchial angles, including the right and left bronchial angles, and the interbronchial angle, in the fetus at various gestational ages. Material/Methods Using methods of anatomical dissection, digital image analysis with an adequate program (NIS-Elements BR 3.0, Nikon), and statistics, values of the two bronchial angles and their sum as the interbronchial angle were semi-automatically measured in 73 human fetuses at the age of 14–25 weeks, derived from spontaneous abortions and stillbirths. Results No male-female differences between the parameters studied were found. The 3 fetal tracheo-bronchial angles were found to be independent of age. The right bronchial angle ranged from 11.4° to 41.8°, and averaged 26.9±7.0° for the whole analyzed sample. The values of left bronchial angle varied from 24.8° to 64.8°, with the overall mean of 46.2±8.0°. As a consequence, the interbronchial angle totalled 36.2–96.6°, and averaged 73.1±12.7°. Conclusions The tracheo-bronchial angles change independently of sex and fetal age. The left bronchial angle is wider than the right one. Values of the 3 tracheo-bronchial angles are unpredictable since their regression curves of best fit with relation to fetal age cannot be modelled. Both of the 2 bronchial angles and the interbronchial angle are of great relevance in the location of inhaled foreign bodies, and in the diagnosis cardiac diseases and mediastinal abnormalities. PMID:23857411

Daroszewski, Marcin; Szpinda, Micha?; Wi?niewski, Marcin; Flisi?ski, Piotr; Szpinda, Anna; WoŸniak, Alina; Kosi?ski, Adam; Grzybiak, Marek; Mila-Kierzenkowska, Celestyna

2013-01-01

253

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

254

Simple technique for the fabrication of a penta prism with high accuracy right angle deviation.  

PubMed

What we believe to be a new technique for the fabrication of a penta prism (PP) with high accuracy right angle deviation of the incident beam is presented. We derive simple formulas relating to the error in right angle deviation with the errors in 45 degrees (beta) and 90 degrees (delta) angles of a PP, and we determine error in right angle deviation from the angle ((error in right angle deviation)r) between the plane wavefronts reflected from the right angled surfaces (external Fresnel reflection on the entrance surface and internal Fresnel reflection on the exit surface) of a PP and the angular error (delta) between the same surfaces. The error in right angle deviation is determined from the measurement of (error in right angle deviation)r using an autocollimator and a Fizeau interferometer, and error in right angle deviation is corrected to a high order of accuracy during the final stage of polishing one of the slanted surfaces of the PP. A new technique to determine the magnitude and direction of the small values of (error in right angle deviation)r is proposed and verified. The result for a PP is presented. PMID:17846645

Chatterjee, Sanjib; Pavan Kumar, Y

2007-09-10

255

A Climbing Class' Reinvention of Angles  

ERIC Educational Resources Information Center

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

Fyhn, Anne Birgitte

2008-01-01

256

Automatic star-horizon angle measurement system  

NASA Technical Reports Server (NTRS)

Automatic star horizontal angle measuring aid for general navigational use incorporates an Apollo type sextant. The eyepiece of the sextant is replaced with two light detectors and appropriate circuitry. The device automatically determines the angle between a navigational star and a unique point on the earths horizon as seen on a spacecraft.

Koerber, K.; Koso, D. A.; Nardella, P. C.

1969-01-01

257

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

258

Firing angle optimisation for chain cell converters  

Microsoft Academic Search

Firing angles for chain cell multi-level converters can be optimised to reduce waveform distortion. Optimisation techniques have previously been developed that calculate the required firing angles, but these techniques fall short of accurate optimisation due to over-simplification of the problem. Established optimisation routines often only work on a subset of possible converter modes, hence optimal solutions are not produced for

D. W. Sandells; T. C. Green

2001-01-01

259

Classification procedure in limited angle tomography system  

SciTech Connect

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

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

2011-06-23

260

Delta wing surface pressures for high angle of attack maneuvers  

NASA Technical Reports Server (NTRS)

A wind tunnel experiment was performed on a delta wing with a leading edge sweep of 70 deg. Unsteady pressures were measured on the suction surface of the wing as it was oscillated from 0-30 deg, and 2-60 deg angle-of-attack. Pressure coefficients were measured at different surface locations for two pitch rates. Static pressure measurements were also obtained for comparison with the dynamic results. The Reynolds number was fixed at 420,000, based on the centerline chord length. Pressure measurements were made from 35-90 percent of the chord, along a ray from the apex at 60 percent of the local semispan. Spanwise measurements were also made at a constant chord location, x/c = 75 percent from the apex. The unsteady pressure data over the 0-30 deg angle-of-attack range showed pressures fluctuating in phase with model motion, and little overshoot from the static values. The pressures for the large amplitude motion showed large overshoots from the static values. In addition, during the high angle-of-attack portion of the motion, the upstroke (angle of attack increasing) pressure coefficients were typically much lower than the downstroke values. For the lower pitch rate, there was little difference between upstroke and downstroke pressures at the low angles of attack.

Thompson, S. A.; Batill, S. M.; Nelson, R. C.

1990-01-01

261

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.

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

2015-01-01

262

Non-Contact Ultrasonic Characterization of Angled Surface Defects  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

263

Planar covariation of elevation angles in prosthetic gait.  

PubMed

In order to achieve efficacious walking, transfemoral amputees must adapt coordination within both the artificial and the sound lower limb. We analyzed kinematic strategies in amputees using the planar covariation of lower limb segments approach. When the elevation angles of the thigh, shank and foot are plotted one versus the others, they describe a regular loop which lies close to a plane in normal adults' gait. Orientation of this plane changes with increased speed, in relation to mechanical energetic saving. We used an opto-electronic device to record the elevation angles of both limbs' segments of novice and expert transfemoral amputees and compared them to those of control subjects. The statistical structure underlying the distribution of these angles was described by principal component analysis and Fourier transform. The typical elliptic loop was preserved in prosthetic walking, in both limbs in both novice and expert transfemoral amputees. This reflects a specific control over the thigh elevation angle taking into account knowledge of the other elevation angles throughout the gait cycle. The best-fitting plane of faster trials rotates around the long axis of the gait loop with respect to the plane of slower trials for control subjects, and even more for the sound limb of expert amputees. In contrast, plane rotation is very weak or absent for the prosthetic limb. We suggest that these results reveal a centrally commanded compensation strategy. PMID:22257927

Leurs, F; Bengoetxea, A; Cebolla, A M; De Saedeleer, C; Dan, B; Cheron, G

2012-04-01

264

Deflection angle of light in an Ellis wormhole geometry  

NASA Astrophysics Data System (ADS)

We reexamine the light deflection by an Ellis wormhole. The bending angle as a function of the ratio between the impact parameter and the throat radius of the wormhole is obtained in terms of a complete elliptic integral of the first kind. This result immediately yields asymptotic expressions in the weak field approximation. It is shown that an expression for the deflection angle derived (and used) in recent papers is valid at the leading order but it breaks down at the next order because of the nontrivial spacetime topology.

Nakajima, Koki; Asada, Hideki

2012-05-01

265

THz dichroic plates for use at high angles of incidence  

NASA Technical Reports Server (NTRS)

The design of a high frequency dichroic plate consisting of an electrically thick self supporting metallic mesh that can be used in a linearly polarized quasi-optical system at high angles of incidence is described. The measured and computed performance of a 2.5-inch aperture mesh is given. This mesh has a 3-dB cutoff frequency of 875 GHz and less than 0.75 dB of transmission loss from 950-1350 GHz at incidence angles of 0, 30, and 45 degrees. The results of a multimode waveguide analysis corroborate the measured data.

Siegel, Peter H.; Dengler, Robert J.; Chen, Jacqueline C.

1991-01-01

266

Development of Tibiofemoral Angle in Korean Children  

PubMed Central

This study was performed to identify the chronological changes of the knee angle or the tibiofemoral angles in normal healthy Korean children. Full-length anteroposterior view standing radiographs of 818 limbs of 452 Korean children were analyzed. The overall patterns of the chronological changes in the knee angle were similar to those described previously in western or Asian children, but the knee angle development was delayed, i.e., genu varum before 1 yr, neutral at 1.5 yr, increasing genu valgum with maximum a value of 7.8° at 4 yr, followed by a gradual decrease to approximately 5-6° of genu valgum of the adult level at 7 to 8 yr of age. These normative data on chronological changes of knee angles should be taken into consideration when evaluating lower limb alignment in children. PMID:18756063

Yoo, Jae Ho; Cho, Tae-Joon; Chung, Chin Youb; Yoo, Won Joon

2008-01-01

267

Acute bilateral angle closure glaucoma induced by methazolamide  

PubMed Central

Purpose To report a case of bilateral acute myopia and angle closure glaucoma after ingestion of methazolamide. Methods An interventional case report of a 70-year-old male who developed bilateral, acute myopia and angle closure glaucoma after ingesting methazolamide tablets for the treatment of normal tension glaucoma. Results Bilateral anterior chamber shallowing associated with ciliary body edema, supraciliary effusions, and shallow posterior choroidal effusions were documented with slit-lamp photography and high-frequency ultrasonography. Near complete resolution of these signs after discontinuation of methazolamide were also documented. Conclusion Methazolamide may be associated with secondary myopia and angle closure glaucoma. Discontinuation of methazolamide leads to resolution of this process, as documented by slit-lamp photography and high-frequency ultrasonography. PMID:23430961

Aref, Ahmad A; Sayyad, Fouad E; Ayres, Bernadete; Lee, Richard K

2013-01-01

268

Spectrogoniometer for measuring planetary surface materials at small phase angles  

NASA Technical Reports Server (NTRS)

This paper describes an instrument, termed spectrogoniometer, which was designed to measure the bidirectional reflectance properties of planetary surface analogs at very small phase angles. By using a pellicle beam splitter, a highly collimated laser light source, and a carefully aligned apparatus it was possible to measure the reflectance properties of geologic samples under any viewing geometry: the angles of incidence and emission ranging from 0 to 90 deg, and the azimuthal angle ranging from 0 to 360 deg. The results on the effect of porosity are demonstrated by comparing measurements on a compact sample (with a void space of 25 percent) and a fluffy sample (with a void space of 90 percent). The fluffy sample exhibited a 30-percent increase in intensity between 10 and 0 deg, whereas the compact sample exhibited only a 20-percent increase.

Buratti, Bonnie J.; Smythe, William D.; Nelson, Robert M.; Gharakhani, Vachik

1988-01-01

269

Adhesion of biologically inspired vertical and angled polymer microfiber arrays.  

PubMed

This paper proposes an approximate adhesion model for fibrillar adhesives for developing a fibrillar adhesive design methodology and compares numerical simulation adhesion results with macroscale adhesion data from polymer microfiber array experiments. A technique for fabricating microfibers with a controlled angle is described for the first time. Polyurethane microfibers with different hardnesses, angles, and aspect ratios are fabricated using optical lithography and polymer micromolding techniques and tested with a custom tensile adhesion measurement setup. Macroscale adhesion and overall work of adhesion of the microfiber arrays are measured and compared with the models to observe the effect of fiber geometry and preload. The adhesion strength and work of adhesion behavior of short and long vertical and long angled fiber arrays have similar trends with the numerical simulations. A scheme is also proposed to aid in optimized fiber adhesive design. PMID:17284057

Aksak, Burak; Murphy, Michael P; Sitti, Metin

2007-03-13

270

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

271

Analysis and design of wide-angle foveated optical systems  

NASA Astrophysics Data System (ADS)

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

Curatu, George

2009-12-01

272

Intrarater and Interrater Reliability of the Flexicurve Index, Flexicurve Angle, and Manual Inclinometer for the Measurement of Thoracic Kyphosis  

PubMed Central

Objective. This study aimed to describe the interrater and intrarater reliability of the flexicurve index, flexicurve angle, and manual inclinometer in swimmers. A secondary objective was to determine the level of agreement between the inclinometer angle and the flexicurve angle and to provide an equation to approximate one angle from the other. Methods. Thirty swimmers participated. Thoracic kyphosis was measured using the flexicurve and the manual inclinometer. Intraclass correlation coefficient, 95% confidence interval, and standard error of measurement were computed. Results. The flexicurve angle and index showed excellent intrarater (ICC = 0.94) and good interrater (ICC = 0.86) reliability. The inclinometer demonstrated excellent intrarater (ICC = 0.92) and interrater (ICC = 0.90) reliability. The flexicurve angle was systematically smaller and correlated poorly with the inclinometer angle (R2 = 0.384). The following equations can be used for approximate conversions: flexicurve angle = (0.275 × inclinometer angle) + 8.478; inclinometer angle = (1.396 × flexicurve angle) + 8.694. Conclusion. The inclinometer and flexicurve are both reliable instruments for thoracic kyphosis measurement in swimmers. Although the flexicurve and inclinometer angles are not directly comparable, the approximate conversion factors provided will permit translation of flexicurve angle to inclinometer angle and vice versa. PMID:24396603

Lewis, Jeremy

2013-01-01

273

Angular dependence of the electronic energy loss of 800-keV He ions along the Si{l_angle}100{r_angle} direction  

SciTech Connect

We present measurements of the stopping power of 800-keV {sup 4}He ions channeled along the Si{l_angle}100{r_angle} axis, as a function of the incidence angle. We compare the experimental results with theoretical calculations by using the impact-parameter-dependent energy loss obtained from the solution of the time-dependent Schr{umlt o}dinger equation through the coupled-channel method. This nonperturbative calculation provides reliable energy-loss results which are in good agreement with the experimental results. {copyright} {ital 1997} {ital The American Physical Society}

dos Santos, J.H.; Grande, P.L.; Behar, M.; Boudinov, H. [Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970, Porto Alegre (Brazil)] [Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970, Porto Alegre (Brazil); Schiwietz, G. [Bereich F, Hahn-Meitner-Institut Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany)] [Bereich F, Hahn-Meitner-Institut Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany)

1997-02-01

274

Angle sensing with ferromagnetic nanowire arrays  

NASA Astrophysics Data System (ADS)

Hysteresis loops and Ferromagnetic Resonance (FMR) linewidths of Nickel ferromagnetic nanowire arrays are measured versus angle ?H between the applied magnetic field angle and the common nanowire axis. Using Preisach analysis, we extract from the hysteresis loop an interaction parameter ?i that strongly depends on ?H. Extending the analysis to FMR lineshapes, we deduce a strong dependence of the FMR field linewidth ?H on ?H through the interaction parameter ?i. Existence of a link between static (hysteresis) and dynamic (FMR) cases through ?H might be exploited in contactless absolute angle sensing devices that could compete with inductive, Hall, and magnetoresistive devices.

Tannous, C.; Gieraltowski, J.

2014-01-01

275

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

276

Wide-angle vision for road views  

NASA Astrophysics Data System (ADS)

The field-of-view of a wide-angle image is greater than (say) 90 degrees, and so contains more information than available in a standard image. A wide field-of-view is more advantageous than standard input for understanding the geometry of 3D scenes, and for estimating the poses of panoramic sensors within such scenes. Thus, wide-angle imaging sensors and methodologies are commonly used in various road-safety, street surveillance, street virtual touring, or street 3D modelling applications. The paper reviews related wide-angle vision technologies by focusing on mathematical issues rather than on hardware.

Huang, F.; Fehrs, K.-K.; Hartmann, G.; Klette, R.

2013-03-01

277

Phase-angle controller for Stirling engines  

NASA Technical Reports Server (NTRS)

An actuator includes a restraint link adapted to be connected with a pivotal carrier arm for a force transfer gear interposed between the crankshaft for an expander portion of a Stirling engine and a crankshaft for the displacer portion of the engine. The restraint link is releasably trapped hydraulic fluid for selectively establishing a phase angle relationship between the crankshaft. A second embodiment incorporates a hydraulic coupler for use in varying the phase angle of gear-coupled crank fpr a Stirling engine whereby phase angle changes are obtainable.

Mcdougal, A. R. (inventor)

1980-01-01

278

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

279

A Control of the MMF Space Harmonic Parasitic Torques in the concentrated winding AC Machine Using Skew angle Optimization  

Microsoft Academic Search

In this study, the authors proposed a method of controlling harmonic parasitic torque in concentrated winding induction motor and validated its theory's practicality through the experiment. To control harmonic, the rotor was skewed at an angle and to determine optimum skew angle, three dimensional electromagnetic analysis was performed. The result of analysis demonstrated larger than 20 degree skew angle, which

Hyun Rok Cha; Cheol Ho Yun; Tae Uk Jung; Hyung Mo Kim; Jeong Cheol Kim; Seung Hun Baek; Kwang Heon Kim

2006-01-01

280

MRO Mars Color Imager (MARCI) Investigation Primary Mission Results  

NASA Astrophysics Data System (ADS)

The Mars Reconnaissance Orbiter (MRO) Mars Color Imager (MARCI) investigation was designed to recover the wide angle camera science objectives of the Mars Climate Orbiter MARCI which was destroyed upon arrival at Mars in 1999 and extend the daily meteorological coverage of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle investigation that was systematically conducted from March 1999 to October 2006. MARCI consists of two wide angle cameras, each with a 180° field of view. The first acquires data in 5 visible wavelength channels (420, 550, 600, 650, 720 nm), the second in 2 UV channels (260, 320 nm). Data have been acquired daily, except during spacecraft upsets, since 24 September 2006. From the MRO 250 to 315 km altitude orbit, inclined 93 degrees, visible wavelength images usually have a pixel scale of about 1 km at nadir and the UV data are at about 8 km per pixel. Data are obtained during every orbit on the day side of the planet from terminator to terminator. These provide a nearly continuous record of meteorological events and changes in surface frost and albedo patterns that span more than 1 martian year and extend the daily global record of such events documented by the MGS MOC. For a few weeks in September and October 2006, both camera systems operated simultaneously, providing views of weather events at about 1400 local time (MOC) and an hour later at about 1500 (MARCI). The continuous meteorological record, now spanning more than 5 Mars years, shows very repeatable weather from year to year with cloud and dust-raising events occurring in the same regions within about 2 weeks of their prior occurrence in previous years. This provides a measure of predictability ideal for assessing future landing sites, orbiter aerobraking plans, and conditions to be encountered by the current landed spacecraft on Mars. However, less predictable are planet-encircling dust events. MOC observed one in 2001, the next was observed by MARCI in 2007. These occurred at different times of year. While popularly known as global dust storms, the nomenclature is misleading, as in each case a storm did not raise dust nor saltate sand on a global basis. Instead, multiple regional storms created a dust haze which obscured much of the martian surface from viewpoints above the lower atmosphere, but in each case the dust opacity was never so high that one could not determine where dust was being raised and where it was not. Within weeks of the end of the 2001 and 2007 global dust events, martian weather returned to its normal, repeatable pattern, with one exception: occasionally thereafter, dust storms were observed in regions where dust-raising had not been seen in the previous years. In these cases, winds capable of raising dust likely occurred at that location every year, but only became visible following a planet-encircling dust event and deposition of dust on a surface that previously did not have sufficient dust to raise. Other MARCI results center on seasonal monitoring of water vapor in the atmosphere, particularly by taking advantage of the anti-correlation between ozone (observable using the UV channels) and water vapor. Owing to their higher spatial resolution than the MOC daily global coverage, details of seasonal polar cap retreat became more apparent, as with these data it is now possible to separate surface frost from ground-hugging fog which forms along the retreating cap edge. MARCI images and meteorological observations are posted weekly on the Internet for public consumption, and the data are archived every 6 months with the NASA Planetary Data System.

Edgett, K. S.; Cantor, B. A.; Malin, M. C.; Science; Operations Teams, M.

2008-12-01

281

Testing cosmic microwave background polarization data using position angles  

NASA Astrophysics Data System (ADS)

We consider a novel null test for contamination which can be applied to cosmic microwave background (CMB) polarization data that involves analysis of the statistics of the polarization position angles. Specifically, we will concentrate on using histograms of the measured position angles to illustrate the idea. Such a test has been used to identify systematics in the NRAO-VLA Sky Survey point source catalogue with an amplitude well below the noise level. We explore the statistical properties of polarization angles in CMB maps. If the polarization angle is not correlated between pixels, then the errors follow a simple ?{N_{pix}} law. However, this is typically not the case for CMB maps since these have correlations which result in an increase in the variance as the effective number of independent pixels is reduced. Then, we illustrate how certain classes of systematic errors can result in very obvious patterns in these histograms, and thus that these errors could possibly be identified using this method. We discuss how this idea might be applied in a realistic context, and make a preliminary analysis of the Wilkinson Microwave Anisotropy Probe 7 data, finding evidence of a systematic error in the Q- and W- band data, consistent with a constant offset in Q and U.

Preece, Michael; Battye, Richard A.

2014-10-01

282

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

283

Nanofluid surface wettability through asymptotic contact angle.  

PubMed

This investigation introduces the asymptotic contact angle as a criterion to quantify the surface wettability of nanofluids and determines the variation of solid surface tensions with nanofluid concentration and nanoparticle size. The asymptotic contact angle, which is only a function of gas-liquid-solid physical properties, is independent of droplet size for ideal surfaces and can be obtained by equating the normal component of interfacial force on an axisymmetric droplet to that of a spherical droplet. The technique is illustrated for a series of bismuth telluride nanofluids where the variation of surface wettability is measured and evaluated by asymptotic contact angles as a function of nanoparticle size, concentration, and substrate material. It is found that the variation of nanofluid concentration, nanoparticle size, and substrate modifies both the gas-liquid and solid surface tensions, which consequently affects the force balance at the triple line, the contact angle, and surface wettability. PMID:21338112

Vafaei, Saeid; Wen, Dongsheng; Borca-Tasciuc, Theodorian

2011-03-15

284

Brownian motion on a sphere: distribution of solid angles  

NASA Astrophysics Data System (ADS)

We study the diffusion of Brownian particles on the surface of a sphere and compute the distribution of solid angles enclosed by the diffusing particles. This function describes the distribution of geometric phases in two-state quantum systems (or polarized light) undergoing random evolution. Our results are also relevant to recent experiments which observe the Brownian motion of molecules on curved surfaces such as micelles and biological membranes. Our theoretical analysis agrees well with the results of computer experiments.

Krishna, M. M. G.; Samuel, Joseph; Sinha, Supurna

2000-09-01

285

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

NASA Astrophysics Data System (ADS)

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

Bryant, P. J.

286

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

SciTech Connect

A series of preliminary experiments has been completed to delineate the combinations of passive cyclic pitching conditions which are favorable. The conditions surveyed have included: upwind and downwind modes of operation; a wide range of delta/sub 3/ angle settings, from +70/sup 0/ to -70/sup 0/; rotor angular speeds from 300 to 750 rpm and the resulting ranges of teeter angles and yaw rates. Negative settings of the delta/sub 3/ angle and large positive delta/sub 3/ values caused pronounced instabilities for both upwind and downwind modes. With delta/sub 3/ angle settings from 0/sup 0/ to 45/sup 0/ the teetered rotor in the downwind mode ran at a continuous yaw angle to the free stream wind. Midrange delta/sub 3/ angle values for an upwind, tailvane stabilized, rotor were favorable.

Bryant, P.J.

1984-01-01

287

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

288

Contact angle hysteresis on superhydrophobic stripes  

NASA Astrophysics Data System (ADS)

We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, ?S. It is shown that the receding regime is determined by a longitudinal sliding motion of 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 ?S. To interpret this we develop a theoretical model, which shows that the value of the receding angle depends both on weak defects at smooth solid areas and on the strong defects due to the elastic energy of the deformed contact line, which scales as ? _S^2 ln ? _S. The advancing contact angle was found to be anisotropic, except in a dilute regime, and its value is shown to be determined by the rolling motion of the drop. The cosine of the longitudinal advancing angle depends linearly on ?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 ?S ? 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 caused by the adhesion of the drop on solid sectors and is proportional to ? _S^2. Finally, the contact angle hysteresis is found to be quite large and generally anisotropic, but it becomes isotropic when ?S ? 0.2.

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

2014-08-01

289

Contact angle hysteresis on superhydrophobic stripes.  

PubMed

We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, ?S. It is shown that the receding regime is determined by a longitudinal sliding motion of 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 ?S. To interpret this we develop a theoretical model, which shows that the value of the receding angle depends both on weak defects at smooth solid areas and on the strong defects due to the elastic energy of the deformed contact line, which scales as ?S(2)ln?S. The advancing contact angle was found to be anisotropic, except in a dilute regime, and its value is shown to be determined by the rolling motion of the drop. The cosine of the longitudinal advancing angle depends linearly on ?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 ?S ? 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 caused by the adhesion of the drop on solid sectors and is proportional to ?S(2). Finally, the contact angle hysteresis is found to be quite large and generally anisotropic, but it becomes isotropic when ?S ? 0.2. PMID:25149809

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

2014-08-21

290

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

291

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

292

Substorm onset location and dipole tilt angle  

NASA Astrophysics Data System (ADS)

From an initial data set of over 200 substorms we have studied a subset of 30 magnetospheric substorms close to magnetic midnight to investigate, in a statistical fashion, the source region of the auroral arc that brightens at the onset of expansive phase. This arc is usually identified as the ionospheric signature of the expansive phase onset that occurs in the magnetotail. All the substorm onsets were identified via ground-based magnetometer and photometer data from the CANOPUS array. Various Tsyganenko global magnetic field models were used to map magnetic field lines from the location of the onset arc out to its greatest radial distance in the magnetotail. The results appear to favour the current disruption model of substorms since the average onset location has an average of 14.1 Earth radii (RE) and is therefore more consistent with theories that place the onset location in the inner magnetotail. For the narrow range of tilts available our modeling indicates the parameter that appears to strongly influence the location of the substorm onset is the dipole tilt angle; as tilt becomes less negative onsets occur further downtail.

Wanliss, J.

2006-03-01

293

Studies of the dynamic contact angle  

NASA Astrophysics Data System (ADS)

The factors affecting the contact or boundary angle (theta) between a gas-liquid interface and a solid vertical wall are investigated experimentally, with a focus on the dynamic case where a solid object is immersed in a liquid. The apparatus employs a high-precision five-phase step motor to immerse a glass plate or circular cylinder into ethylene glycol or glycerine at 20 C and then retract it, an He-Ne-laser/Xe-flashlamp illumination system, and an optical bench equipped with a microscope and camera. The results are presented in a graph, and the relationships between theta and the six parameters gravity, fluid density and dynamic viscosity, surface tension, characteristic length, and solid-body velocity are explored. Regression analysis gives the dependence equation theta = 175 x (Ca exp -0.81)(Fr exp 0.5)(M exp 0.23), where Ca is the capillarity (Weber number divided by Reynolds number), Fr is the Froude number, and M is the Morton number.

Siekmann, Julius; Zimmermann, Elisabeth

294

Effectiveness of Variable-Gain Kalman Filter Based on Angle Error Calculated from Acceleration Signals in Lower Limb Angle Measurement with Inertial Sensors  

PubMed Central

The wearable sensor system developed by our group, which measured lower limb angles using Kalman-filtering-based method, was suggested to be useful in evaluation of gait function for rehabilitation support. However, it was expected to reduce variations of measurement errors. In this paper, a variable-Kalman-gain method based on angle error that was calculated from acceleration signals was proposed to improve measurement accuracy. The proposed method was tested comparing to fixed-gain Kalman filter and a variable-Kalman-gain method that was based on acceleration magnitude used in previous studies. First, in angle measurement in treadmill walking, the proposed method measured lower limb angles with the highest measurement accuracy and improved significantly foot inclination angle measurement, while it improved slightly shank and thigh inclination angles. The variable-gain method based on acceleration magnitude was not effective for our Kalman filter system. Then, in angle measurement of a rigid body model, it was shown that the proposed method had measurement accuracy similar to or higher than results seen in other studies that used markers of camera-based motion measurement system fixing on a rigid plate together with a sensor or on the sensor directly. The proposed method was found to be effective in angle measurement with inertial sensors. PMID:24282442

Watanabe, Takashi

2013-01-01

295

Spirality: A Noval Way to Measure Spiral Arm Pitch Angle  

NASA Astrophysics Data System (ADS)

We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. For a given pitch angle template, the mean pixel value is found along each of typically 1000 spiral axes. The fitting function, which shows a local maximum at the best-fit pitch angle, is the variance of these means. Error bars are found by varying the inner radius of the measurement annulus and finding the standard deviation of the best-fit pitches. Computation time is typically on the order of 2 minutes per galaxy, assuming at least 8 GB of working memory. We tested the code using 128 synthetic spiral images of known pitch. These spirals varied in the number of spiral arms, pitch angle, degree of logarithmicity, radius, SNR, inclination angle, bar length, and bulge radius. A correct result is defined as a result that matches the true pitch within the error bars, with error bars no greater than ±7°. For the non-logarithmic spiral sample, the correct answer is similarly defined, with the mean pitch as function of radius in place of the true pitch. For all synthetic spirals, correct results were obtained so long as SNR > 0.25, the bar length was no more than 60% of the spiral's diameter (when the bar was included in the measurement), the input center of the spiral was no more than 6% of the spiral radius away from the true center, and the inclination angle was no more than 30°. The synthetic spirals were not deprojected prior to measurement. The code produced the correct result for all barred spirals when the measurement annulus was placed outside the bar. Additionally, we compared the code's results against 2DFFT results for 203 visually selected spiral galaxies in GOODS North and South. Among the entire sample, Spirality's error bars overlapped 2DFFT's error bars 64% of the time. For those galaxies in which Source code is available by email request from the primary author.

Shields, Douglas W.; Boe, Benjamin; Henderson, Casey L.; Hartley, Matthew; Davis, Benjamin L.; Pour Imani, Hamed; Kennefick, Daniel; Kennefick, Julia D.

2015-01-01

296

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

297

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

298

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

299

Quark and lepton mixing angles with a dodeca-symmetry  

NASA Astrophysics Data System (ADS)

The discrete symmetry D 12 at the electroweak scale is used to fix the quark and lepton mixing angles. At the leading order, the Cabbibo angle ? C is 15°, and the PMNS matrix is of a bi-dodeca-mixing form giving the Solar-neutrino angle ? sol = 30°. Thus, there results the relation ? sol + ? C ? 45°. Out of discrete vacua, a certain vacuum is chosen for this assignment to be consistent with the dodeca-symmetry. A shift of ? C from 15° to 13.14° might arise from a small breaking of the dodeca-symmetry. The spontaneous breaking leading to the required electroweak vacuum is made possible by realizing the electroweak dodeca-symmetry explicitly at a high energy scale. At the vacuum we chose Arg.Det. M q is nonzero, and hence a solution of the strong CP problem invites a very light axion at a high energy scale. We also comment how the next level corrections can fit the mixing angles to the observed values. An example realizing this idea needs a symmetry SU(3) c × SU(2) L × U(1) Y × D 12 × U(1)? × Z 3 × Z 2.

Kim, Jihn E.; Seo, Min-Seok

2011-02-01

300

Relating dynamic contact angle to wetting front instability  

NASA Astrophysics Data System (ADS)

Dynamic contact angles have been implied as a mechanism for initiating the instability of wetting fronts and the formation of gravity fingers/columns in porous media. To study those dynamic contact angles when gravity effects are present, rectangular capillary tubes are used to facilitate the observation of the complete interface without geometric distortion. Results show that the dynamic contact angle minus the static contact angle has a unique relationship with the capillary number which is function of the velocity of the slug, and surface tension and viscosity of the fluid. Using this relationship and making the assumption that the fluid velocity through the pores is related but not equal to the finger velocity, earlier findings of DiCarlo on the capillary overshoot at the wetting front can be reproduced well. This study confirms that dynamic contact plays a critical role in the formation of unstable finger flow. It also points a way to calculate the capillary pressure at the wetting from as a function of the flux in the finger and the grain size diameter.

Baver, Christine; Parlange, J.-Yves; Stoof, Cathelijne; DiCarlo, David; Wallach, Rony; Steenhuis, Tammo

2013-04-01

301

Contact angle hysteresis and pinning at periodic defects in statics.  

PubMed

This article deals with the theoretical prediction of the wetting hysteresis on nonideal solid surfaces in terms of the surface heterogeneity parameters. The spatially periodical chemical heterogeneity is considered. We propose precise definitions for both the advancing and the receding contact angles for the Wilhelmy plate geometry. It is well known that in such a system, a multitude of metastable states of the liquid meniscus occurs for each different relative position of the defect pattern on the plate with respect to the liquid level. As usual, the static advancing and receding angles are assumed to be a consequence of the preceding contact line motion in the respective direction. It is shown how to select the appropriate states among all metastable states. Their selection is discussed. The proposed definitions are applicable to both the static and the dynamic contact angles on heterogeneous surfaces. The static advancing and receding angles are calculated for two examples of periodic heterogeneity patterns with sharp borders: the horizontal alternating stripes of a different wettability (studied analytically) and the doubly periodic pattern of circular defects on a homogeneous base (studied numerically). The wetting hysteresis is determined as a function of the defect density and the spatial period. A comparison with the existing results is carried out. PMID:25122314

Iliev, Stanimir; Pesheva, Nina; Nikolayev, Vadim S

2014-07-01

302

Control considerations for CCV fighters at high angles of attack  

NASA Technical Reports Server (NTRS)

Wind tunnel and piloted simulation studies were conducted to investigate the potential high angle of attack control problems that are introduced by the use of the CCV concept of relaxed static pitch stability (RSS) on fighter aircraft. A conventional wing/aft tail design incorporating modest levels of static instability and a close-coupled canard/wing design exhibiting very high levels of instability was investigated. Two types of high angle of attack control problems can result from the use of RSS: pitch departures caused by coupling and deep stall trim. Avoidance of these problems requires that the airplane have sufficient nose-down pitch control at high angles of attack. The effectiveness of several pitch control configurations were investigated including conventional aft-mounted stabilators, wing-mounted elevators, canard-mounted flaps, and all-moveable canards. Varying the incidence of the canards was the most effective scheme; however, very large deflections may be required on highly unstable configurations to prevent pitch departure without sacrificing roll performance and to avoid deep stall trim. For situations where the high angle of attack pitch control requirement is not met, control laws were developed to inhibit the departure and to allow deep stall recovery. However, these schemes involve limiting airplane roll capability and therefore can potentially compromise maneuverability.

Nguyen, L. T.; Gilbert, W. P.; Grafton, S. B.

1979-01-01

303

Broadband "Infinite-Speed" Magic-Angle Spinning NMR Spectroscopy  

SciTech Connect

High-resolution magic-angle spinning NMR of high-Z spin- 1/2 nuclei such as {sup 125}Te, {sup 207}Pb, {sup 119}Sn, {sup 113}Cd, and {sup 195}Pt is often hampered by large (>1000 ppm) chemical-shift anisotropies, which result in strong spinning sidebands that can obscure the centerbands of interest. In various tellurides with applications as thermoelectrics and as phase-change materials for data storage, even 22-kHz magic-angle spinning cannot resolve the center- and sidebands broadened by chemical-shift dispersion, which precludes peak identification or quantification. For sideband suppression over the necessary wide spectral range (up to 200 kHz), radio frequency pulse sequences with few, short pulses are required. We have identified Gan's two-dimensional magic-angle-turning (MAT) experiment with five 90{sup o} pulses as a promising broadband technique for obtaining spectra without sidebands. We have adapted it to broad spectra and fast magic-angle spinning by accounting for long pulses (comparable to the dwell time in t{sub 1}) and short rotation periods. Spectral distortions are small and residual sidebands negligible even for spectra with signals covering a range of 1.5 {gamma}B{sub 1}, due to a favorable disposition of the narrow ranges containing the signals of interest in the spectral plane. The method is demonstrated on various technologically interesting tellurides with spectra spanning up to 170 kHz, at 22 kHz MAS.

Hu, Yan-Yan; Levin, E.M; Schmidt-Rohr, Klaus

2009-06-02

304

Contact angle hysteresis and pinning at periodic defects in statics  

NASA Astrophysics Data System (ADS)

This article deals with the theoretical prediction of the wetting hysteresis on nonideal solid surfaces in terms of the surface heterogeneity parameters. The spatially periodical chemical heterogeneity is considered. We propose precise definitions for both the advancing and the receding contact angles for the Wilhelmy plate geometry. It is well known that in such a system, a multitude of metastable states of the liquid meniscus occurs for each different relative position of the defect pattern on the plate with respect to the liquid level. As usual, the static advancing and receding angles are assumed to be a consequence of the preceding contact line motion in the respective direction. It is shown how to select the appropriate states among all metastable states. Their selection is discussed. The proposed definitions are applicable to both the static and the dynamic contact angles on heterogeneous surfaces. The static advancing and receding angles are calculated for two examples of periodic heterogeneity patterns with sharp borders: the horizontal alternating stripes of a different wettability (studied analytically) and the doubly periodic pattern of circular defects on a homogeneous base (studied numerically). The wetting hysteresis is determined as a function of the defect density and the spatial period. A comparison with the existing results is carried out.

Iliev, Stanimir; Pesheva, Nina; Nikolayev, Vadim S.

2014-07-01

305

Simulation and data analysis of infrared ocean clutter at grazing angles  

Microsoft Academic Search

Ocean clutter in infrared images at low grazing angles is of interest for both airborne and shipborne detection of low flying targets over the ocean. In this paper a 2-D simulation model for infrared cutter at low grazing angle and data analysis results of three IRAMMP ocean tests are presented. The data analyzed correspond to IRAMMP calibrated dual band (mid-wave

Philip J. Davis; Erik P. Krumrey; Robert Myers

1993-01-01

306

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

307

A numerical analysis applied to high angle of attack three-dimensional inlets  

NASA Technical Reports Server (NTRS)

The three-dimensional analytical methods used to analyze subsonic high angle of attack inlets are described. The methods are shown to be in good agreement with experimental results for various three-dimensional high angle of attack inlets. The methods are used to predict aerodynamic characteristics of scarf and slotted-lip inlets.

Hwang, D. P.

1986-01-01

308

Long-term evolution of nourished beaches under high angle wave conditions  

Microsoft Academic Search

A nonlinear numerical model for large-scale dynamics of shoreline and nearshore bathymetry under wave action is applied to investigate the long-term evolution of a rectilinear coast dominated by high angle wave incidence, which is perturbed by a nourishment or an offshore borrow pit. Previous studies show that a coastline can be unstable due to high angle wave instability, which results

Niels van den Berg; Albert Falqués; Francesca Ribas

2011-01-01

309

Effects of a Butterfly Scale Microstructure on the Iridescent Color Observed at Different Angles  

Microsoft Academic Search

Multilayer thin-film structures in butterfly wing scales produce a colorful iridescence from reflected sunlight. Because of optical phenomena, changes in the angle of incidence of light and the viewing angle of an observer result in shifts in the color of butterfly wings. Colors ranging from green to purple, which are due to nonplanar specular reflection, can be observed on Papilio

Haruna Tada; Seth E. Mann; Ioannis N. Miaoulis; Peter Y. Wong

1998-01-01

310

Effects of a butterfly scale microstructure on the iridescent color observed at different angles  

Microsoft Academic Search

Multilayer thin-film structures in butterfly wing scales produce a colorful iridescence from reflected sunlight. Because of optical phenomena, changes in the angle of incidence of light and the viewing angle of an observer result in shifts in the color of butterfly wings. Colors ranging from green to purple, which are due to nonplanar specular reflection, can be observed on Papilio

Haruna Tada; Seth E. Mann; Ioannis N. Miaoulis; Peter Y. Wong

1999-01-01

311

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

312

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

313

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

314

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

315

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

316

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

317

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

318

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

319

Calcified vestibular schwannoma in the cerebellopontine angle.  

PubMed

Although vestibular schwannoma is a common tumor in the cerebellopontine angle, calcified vestibular schwannoma is rare. A 59-year-old woman with sudden onset epileptic seizures, was referred to Hokkaido Neurosurgical Memorial Hospital. Neurological examination revealed left Bruns nystagmus, left deafness and left cerebellar ataxia. Brain MRI revealed a mass, about 3cm in diameter, in the left cerebellopontine angle. The mass showed heterogeneous intensity on T1- and T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. Hydrocephalus was seen. On CT scan, the tumor was calcified. Preoperatively, vestibular schwannoma, meningioma, cavernous hemangioma, or thrombosed giant aneurysm were considered as differential diagnoses. The pathological diagnosis was schwannoma. For a calcified mass in the cerebellopontine angle, vestibular schwannoma should be considered in the differential diagnosis to plan appropriate treatment strategies. PMID:17884507

Katoh, Masahito; Aida, Toshimitsu; Imamura, Hiroyuki; Aoki, Takeshi; Yoshino, Masami; Kashiwazaki, Daina; Takei, Hidetoshi

2007-12-01

320

What is the apparent angle of a Kelvin ship wave pattern?  

NASA Astrophysics Data System (ADS)

While the half-angle which encloses a Kelvin ship wave pattern is commonly accepted to be 19.47 degrees, recent observations and calculations for sufficiently fast-moving ships suggest that the apparent wake angle decreases with ship speed. One explanation for this decrease in angle relies on the assumption that a ship cannot generate wavelengths much greater than its hull length. An alternative interpretation is that the wave pattern that is observed in practice is defined by the location of the highest peaks; for wakes created by sufficiently fast-moving objects, these highest peaks no longer lie on the outermost divergent waves, resulting in a smaller apparent angle. In this paper, we focus on the problems of free surface flow past a single submerged point source and past a submerged source doublet. In the linear version of these problems, we measure the apparent wake angle formed by the highest peaks, and observe the following three regimes: a small Froude number pattern, in which the divergent waves are not visible; standard wave patterns for which the maximum peaks occur on the outermost divergent waves; and a third regime in which the highest peaks form a V-shape with an angle much less than the Kelvin angle. For nonlinear flows, we demonstrate that nonlinearity has the effect of increasing the apparent wake angle so that some highly nonlinear solutions have apparent wake angles that are greater than Kelvin's angle. For large Froude numbers, the effect on apparent wake angle can be more dramatic, with the possibility of strong nonlinearity shifting the wave pattern from the third regime to the second. We expect our nonlinear results will translate to other more complicated flow configurations, such as flow due to a steadily moving closed body such as a submarine.

Pethiyagoda, Ravindra; McCue, Scott W.; Moroney, Timothy J.

2014-11-01

321

Numerical Study of Flow Angles and Mach Number Measurement Using the Surface Pressure of a Supersonic Aircraft with Nose Cone  

NASA Astrophysics Data System (ADS)

Numerical simulation of the flow around an air data sensor (ADS), which measures flow angles and Mach numbers using surface pressures on a nose cone, was conducted in this study. Effects of the half-cone angle on the flow angle and Mach number measurements were investigated. Results show that a large half-cone angle achieves high sensitivity of flow angle measurements. Results further demonstrated that a small half-cone angle achieves high-sensitivity of Mach number measurements. To satisfy these conflicting requests, we proposed the use of bi-conic nose cones with two gradients. High sensitivity was achieved for both flow angle measurements and Mach number measurements using this bi-conic nose cone.

Fukiba, Katsuyoshi; Tsuboi, Nobuyuki; Kobayashi, Hiroaki

322

Quantitative kinetics and angle scanning surface plasmon resonance imaging  

NASA Astrophysics Data System (ADS)

Surface plasmon resonance (SPR) has been used extensively to monitor the kinetics of the adsorption of molecules at surfaces. We have quantitatively evaluated the accuracy of three different methods for measuring the kinetics of the adsorption of molecules using SPR by modeling the SPR response for an isotropic optical multilayer system. The SPR kinetic methods included the tracking of the minimum of the SPR reflected intensity and the tracking of the SPR reflected intensity at a fixed angle of incidence theta i, as well as a third novel method, the tracking of the inflection point of the SPR reflected intensity. SPR minimum tracking and SPR inflection point tracking were found to yield quantitatively accurate measures of the time constant tau of the kinetics, whereas the accuracy of the tau values determined using SPR fixed angle reflectivity tracking was found to vary significantly with the choice of fixed thetai. A method was developed to deconvolute the SPR curve shape from the SPR fixed angle reflectivity data resulting in a dramatic increase in the accuracy of the tau values. The SPR kinetic method modeling results were validated by designing and constructing an automated angle scanning SPR imaging instrument. The instrument incorporated a novel method to remove two imaging artifacts, beam walking and image compression, that severely impact the ability to track regions of interest (ROIs) within the image as thetai is varied. By using this novel method, we are able to define multiple ROIs for an arbitrary thetai and correctly track these ROIs at all other values of thetai. In agreement with our modeling results, we show experimentally that the accuracy of the tau values obtained from the SPR fixed angle reflectivity tracking method depends significantly on the choice of fixed theta i, and that the accuracy of the tau values improves dramatically by deconvoluting the SPR curve shape from the SPR fixed angle reflectivity data. We have also used our SPR imaging instrument to study the enzymatic degradation of cellulose fibers that have been heterogeneously distributed on a gold film coated with a thin layer of thioglucose.

Allen, Scott G.

323

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

324

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

325

Ship wakes: Kelvin or Mach angle?  

E-print Network

From the analysis of a set of airborne images of ship wakes, we show that the wake angles decrease as $U^{-1}$ at large velocities, in a way similar to the Mach cone for supersonic airplanes. This previously unnoticed Mach-like regime is in contradiction with the celebrated Kelvin prediction of a constant angle of $19.47\\degree$ independent of the ship's speed. We propose here a model, confirmed by numerical simulations, in which the finite size of the disturbance explains this transition between the Kelvin and Mach regimes at a Froude number $Fr = U/\\sqrt{gL} \\simeq 0.5$, where $L$ is the hull ship length.

Rabaud, Marc

2013-01-01

326

Pitch angles of distant spiral galaxies  

NASA Astrophysics Data System (ADS)

We have studied the pitch angles of spiral arms for 31 distant galaxies at z ˜ 0.7 from three Hubble Deep Fields (HDF-N, HDF-S, HUDF). Using the pitch angle-rotation velocity relation calibrated from nearby galaxies, we have estimated the rotation velocities of galaxies from the deep fields. These estimates have a low accuracy (˜50 km s-1), but they allow low-mass and giant galaxies to be distinguished. The Tully-Fisher relation constructed using our velocity estimates shows satisfactory agreement with the actually observed relations for distant galaxies and provides evidence for the luminosity evolution of spiral galaxies.

Savchenko, S. S.; Reshetnikov, V. P.

2011-12-01

327

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...

328

Photometric theory for wide-angle phenomena  

NASA Astrophysics Data System (ADS)

An examination is made of the problem posed by wide-angle photographic photometry, in order to extract a photometric-morphological history of Comet P/Halley. Photometric solutions are presently achieved over wide angles through a generalization of an assumption-free moment-sum method. Standard stars in the field allow a complete solution to be obtained for extinction, sky brightness, and the characteristic curve. After formulating Newton's method for the solution of the general nonlinear least-square problem, an implementation is undertaken for a canonical data set. Attention is given to the problem of random and systematic photometric errors.

Usher, P. D.

1990-07-01

329

MODIS pre-launch reflective solar band response vs. scan angle  

NASA Astrophysics Data System (ADS)

The MODIS scan mirror reflectance is a function of angle of incidence (AOI). For the MODIS solar reflective bands (RSB), it is specified that the calibrated response variation versus scan angle (RVS) should be less than 2% and the uncertainty of the RVS characterization should be less than 0.5% within the scan angle range of -45° ~ +45°. During MODIS pre-launch RVS calibration and characterization, a series of laboratory tests were performed to assess the relative response versus scans angle for all MODIS bands. Utilizing a Spherical Integrating Source, SIS, as an illumination source, the test data was collected at various angles of incidence. The characterization of the RVS included a measurement uncertainty assessment, repeatability analysis, RVS modeling and determination. The results show good repeatability on the order of less than 0.5% for all the near infrared (NIR) bands and the visible (VIS) bands. The detector response variation across scan angles for the majority of the NIR and VIS bands meets the instrument specification. The derived RVS model enabled appropriate implementation of on orbit calibration. This paper summarizes the methodologies and the algorithms used in the MODIS pre-launch RVS calibration for the RSB bands, illustrates detector response variation with scan mirror angle of incidence, and demonstrates instrument specification compliance within the scan angle coverage of +/-55 degree. As a result, the RVS model and the correction coefficients developed in the pre-launch calibration have been adopted during the MODIS on-orbit calibration.

Pan, Chunhui; Xiong, Jack; Che, Nianzeng

2007-09-01

330

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

331

The effect of large solid angles of collection on quantitative X-ray microanalysis in the AEM.  

PubMed

Increasing the solid angle of X-ray collection is a major factor in improving the analytical sensitivity of X-ray energy-dispersive spectrometry (XEDS) in the analytical electron microscope (AEM). A new scanning transmission electron microscope, the VG HB 603, is equipped with two XEDS detectors with the largest collection angles (0.30 and 0.17 sr) available in commercial AEMs. However, large collection angles result in a large range of take-off angles, from approximately 4 degrees to 36 degrees, and the low angles can cause strong X-ray absorption. In order to investigate possible detrimental effects of the low (and of the range of) take-off angles on quantitative microanalysis of specimens exhibiting significant absorption, a stoichiometric Ni3Al thin-film, in which the Al Kalpha line is significantly absorbed, was analysed. Furthermore, the effect of different values of the collection angle on X-ray intensities was theoretically evaluated by numerical calculations and spectral simulation. These theoretical approaches permitted correlation of changes in the X-ray take-off angle (and hence X-ray absorption) with changes in the collection angle. It is demonstrated that approximately 0.30 sr detectors, with minimum take-off angles as small as 4 degrees, only result in maximum errors of 4% in the quantification of Al in Ni3Al and, therefore, further increases in collection angle can be pursued while maintaining current levels of accuracy of quantification. PMID:10444300

Watanabe, M; Ackland, D W; Williams, D B

1999-07-01

332

Comparison of Factors Associated With Occludable Angle Between American Caucasians and Ethnic Chinese  

PubMed Central

Purpose. To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. Methods. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40–80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ?2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. Results. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Conclusions. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese. PMID:24168992

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-01-01

333

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

334

Tropospheric Scatter System Using Angle Diversity  

Microsoft Academic Search

This paper proposes an extension of the angle diversity technique as a means towards solution of several problems restricting use of over-the-horizon microwave communications. The paper suggests application of a microwave multibeam system as an attack on the problems of transmitter tube limitations, \\

J. H. Vogelman; J. L. Ryerson; M. H. Bickelhaupt

1959-01-01

335

Fizeau interferometer profiles at finite acceptance angles  

Microsoft Academic Search

Instrument profiles of the wedge or Fizeau interferometer are determined under practical conditions. The appearance of subsidiary maxima on the high order side of the central maxima is confirmed, and the behaviour of these is noted as the solid angle of acceptance is varied. From these calculations it is inferred that the acceptable range of use of the instrument could

T A Hall

1969-01-01

336

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

337

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

338

Marine Fisheries Marine recreational angling. Florida  

E-print Network

Marine Fisheries ~~WD~W Marine recreational angling. Florida News Bureau photo by Jack Fortune 1980 Jay D. Andrews 1 Social Considerations Associated With Marine Recreational Fishing Under FCMA/NMFS Developments Index, 1980 Papers in Marine Fisheries Review, 1980 Chad P. Dawson and Bruce T. Wilkins 12 Charles

339

Multi-angle facial image analysis  

Microsoft Academic Search

Fetal Alcohol Syndrome (FAS) is a developmental disorder caused by maternal drinking during pregnancy. Computerized imaging techniques have been applied to study human facial dysmorphology associated with FAS. This thesis mainly describes two new facial image analysis methods: the first method is based on a multi-angle image classification technique using micro-video images of mouse embryo, images taken from several different

Ying Liu

2009-01-01

340

Helical CT Reconstruction with Large Cone Angle  

Microsoft Academic Search

In this work we suggest ways to incorporate redundant data into reconstruction for a range of helical pitches from 1-PI to 3-PI. For evaluation we use simulated data and real 256-slice anthropomorphic phantom data. With large cone angle reconstruction is very sensitive to the exactness of the algorithm.

Alexander A. Zamyatin; Alexander Katsevich; Michael D. Silver; Satoru Nakanishi

2006-01-01

341

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

342

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

343

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

344

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

345

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

346

Studies on RHEED oscillations at low glancing angles  

NASA Astrophysics Data System (ADS)

A new approach for interpreting RHEED intensity oscillations is presented. Only low values of the glancing angle of the incident electron beam are considered. The intensity of the specularly reflected beam is calculated by solving the Schrödinger equation with a one-dimensional model of a scattering potential of a growing film. For low values of the glancing angle (less than 0.5° for an electron energy of 20 keV) such calculations may be expected to lead to similar results to those obtained assuming a three-dimensional model of the potential. In the present paper numerically determined shapes of the intensity oscillations are shown for different cases of deposition of atoms at surfaces of growing films.

Mitura, Z.; Daniluk, A.

1992-10-01

347

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

348

Complex Padé approximant operators for wide-angle beam propagation  

NASA Astrophysics Data System (ADS)

The conventional rational Hadley( m, n) approximant of wide-angle beam propagator based on real Padé approximant operators incorrectly propagates the evanescent modes. In order to overcome this problem, two complex Padé approximants of wide-angle beam propagator are presented in this paper. The complex propagators of the first approach are obtained by using the same recurrence formula from the scalar Helmholtz equation of the conventional approximant method with a different initial value while those of the second method derived from Hadley( m, n) approximant of a square-root operator that has been rotated in the complex plane. These resulting approaches allow more accurate approximations to the Helmholtz equation than the well-known real Padé approximant. Furthermore, our proposed complex Padé approximant operators give the evanescent modes the desired damping.

Le, Khai Q.

2009-04-01

349

Probe Without Moving Parts Measures Flow Angle  

NASA Technical Reports Server (NTRS)

The measurement of local flow angle is critical in many fluid-dynamic applications, including the aerodynamic flight testing of new aircraft and flight systems. Flight researchers at NASA Dryden Flight Research Center have recently developed, flight-tested, and patented the force-based flow-angle probe (FLAP), a novel, force-based instrument for the measurement of local flow direction. Containing no moving parts, the FLAP may provide greater simplicity, improved accuracy, and increased measurement access, relative to conventional moving vane-type flow-angle probes. Forces in the FLAP can be measured by various techniques, including those that involve conventional strain gauges (based on electrical resistance) and those that involve more advanced strain gauges (based on optical fibers). A correlation is used to convert force-measurement data to the local flow angle. The use of fiber optics will enable the construction of a miniature FLAP, leading to the possibility of flow measurement in very small or confined regions. This may also enable the tufting of a surface with miniature FLAPs, capable of quantitative flow-angle measurements, similar to attaching yarn tufts for qualitative measurements. The prototype FLAP was a small, aerodynamically shaped, low-aspect-ratio fin about 2 in. (approximately equal to 5 cm) long, 1 in. (approximately equal to 2.5 cm) wide, and 0.125 in. (approximately equal to 0.3 cm) thick (see Figure 1). The prototype FLAP included simple electrical-resistance strain gauges for measuring forces. Four strain gauges were mounted on the FLAP; two on the upper surface and two on the lower surface. The gauges were connected to form a full Wheatstone bridge, configured as a bending bridge. In preparation for a flight test, the prototype FLAP was mounted on the airdata boom of a flight-test fixture (FTF) on the NASA Dryden F-15B flight research airplane.

Corda, Stephen; Vachon, M. Jake

2003-01-01

350

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

351

Effect of chorus normal angle on dynamic evolution of radiation belt energetic electrons  

NASA Astrophysics Data System (ADS)

Gyroresonance between chorus waves and radiation belt electrons is usually evaluated by using the Gaussian wave normal angle ( X=tan ?) distribution. In this study, we examine the influence of peak wave normal angle ( X m =tan ? m ) on chorus-electron interaction in the heart of radiation belts L=4.5. By varying X m =0,2,4,6, we calculate the bounce-averaged diffusion coefficients, and then simulate the phase space density (PSD) evolution of radiation belt energetic electrons induced by both dayside and nightside chorus waves. Numerical simulations show that diffusion coefficients move to the low pitch angle region and drop rapidly by a factor of ˜10 as X m increases by 2 each time, consequently leading to the smaller amplitude and narrower pitch angle region in electron PSD evolution. The current results demonstrate that chorus-electron interaction in the outer radiation belt is largely dependent on peak wave normal angles.

Zhang, Lewei; He, Yihua; Liu, Si; Yang, Chang; Zhou, Qinghua; Xiao, Fuliang

2014-12-01

352

Numerical investigation of cone angle effect on the flow field and separation efficiency of deoiling hydrocyclones  

NASA Astrophysics Data System (ADS)

In this study, the effect of cone angle on the flow field and separation efficiency of deoiling hydrocyclones is investigated taking advantage of large eddy simulation. The dynamic Smagorinsky is employed to determine the residual stress tensor of the continuous phase. The method of Lagrangian particle tracking with an optimized search algorithm (closest cell) is applied to evaluate the separation efficiency of deoiling hydrocyclone. Simulations are performed on a 35-mm deoiling hydrocyclone with the three different cone angles of 6, 10 and 20 degree. The numerical results revealed that the changes in the cone angle would affect the velocity and pressure distribution inside hydrocyclone, and lead to changes in the separation efficiency. However, the large cone angle increases the tangential velocity and pressure gradient inside the hydrocyclone, but reduces the separation efficiency. The reasons behind the decrease in the separation efficiency are the flow structure and reduction of oil droplets residence time in hydrocyclones with large cone angles.

Saidi, Maysam; Maddahian, Reza; Farhanieh, Bijan

2013-02-01

353

Distortion-free wide-angle 3D imaging and visualization using off-axially distributed image sensing.  

PubMed

We propose a new off-axially distributed image sensing (ODIS) using a wide-angle lens for reconstructing distortion-free wide-angle slice images computationally. In the proposed system, the wide-angle image sensor captures a wide-angle 3D scene, and thus the collected information of the 3D objects is severely distorted. To correct this distortion, we introduce a new correction process involving a wide-angle lens to the computational reconstruction in ODIS. This enables us to reconstruct distortion-free, wide-angle slice images for visualization of 3D objects. Experimental results are carried out to verify the proposed method. To the best of our knowledge, this is the first time the use of a wide-angle lens in a multiple-perspective 3D imaging system is described. PMID:25121689

Zhang, Miao; Piao, Yongri; Kim, Nam-Woo; Kim, Eun-Soo

2014-07-15

354

Numerical Study on Flow Angles and Mach Number Measurement Using the Surface Pressure of a Supersonic Aircraft with Nosecone  

NASA Astrophysics Data System (ADS)

Numerical simulation on the Air Data Sensor System (ADS), which measures the flow angles and Mach number using the surface pressures on a nose cone, was conducted in this study. The effect of the half cone angle on the flow angle and Mach number measurement was investigated. As a result, we found that a large half cone angle achieves a high sensitivity at the flow angle measurement. It was also found that a small half cone angle achieves a high sensitivity at the Mach number measurement. To satisfy these conflicting requests, we proposed a new shape nose cone which has two different gradients. The high sensitivity was achieved at both the flow angle measurement and Mach number measurement by this new shape nose cone.

??, ??; ??, ??; ??, ??

355

Estimation of radio refractivity using a multiple angle clutter model  

E-print Network

is a conse- quence of neglecting the effect of a variable grazing angle on the clutter power at low angles the SPANDAR 1998 data set is provided, using single and multiple grazing angle clutter models]. [5] Most previous RFC studies have considered a grazing angle-independent clutter model. This model

Gerstoft, Peter

356

Intraoral multistage mandibular angle ostectomy: 10 years' experience in mandibular contouring in Asians.  

PubMed

In Asia, a round face rather is more acceptable than a square face. Intraoral mandibular angle ostectomy is a common aesthetic procedure for correcting a prominent mandibular angle. However, an operation of sheer straight-lined prominent mandibular angle resection would sometimes create extramandibular angles or palpable bone steps in the margin of mandibular body and produce unnatural lower one-third facial appearance, especially for a square and disproportional mandibular angle even extending to the middle mandibular body. This article describes the method of multistage mandibular angle ostectomy to produce a natural lower one-third facial contour. This method mainly focused on the posterior area of mandibular ostectomy by intraoral approach, although it has modifications. Mandibular contouring is realized first through bone cutting from antegonial notch posteriorly upperward, reaching to the middle ramus of the mandible near the earlobe; second ostectomy followed along mandible lower part is to get rid of extramandibular angle according to the preoperative design; sometimes necessarily, third ostectomy creates a smooth mandibular contour. From January 2000 to January 2010, 379 patients were operated on, and satisfactory results were achieved. Thus, this procedure could avoid excessive bone cutting, extramandibular angles, unnatural appearance, and palpable bone steps. PMID:21233762

Ying, Binbin; Wu, Sufan; Yan, Sheng; Hu, Jing

2011-01-01

357

Age-related Changes in Maximum Pelvic Anteversion and Retroversion Angles Measured in the Sitting Position  

PubMed Central

[Purpose] The purpose of this study was to investigate the relationship between age and the maximum pelvic anteversion and retroversion angles, as well as the associated pelvic range of motion, measured in a sitting position with free knee movement. [Subjects] A total of 132 healthy volunteers (74 women, 58 men; age range, 20–79 years) were divided into six groups based on age (20–29, 30–39, 40–49, 50–59, 60–69, and 70–79 years). [Methods] The maximum pelvic anteversion and retroversion angles were measured manually five times by a goniometer in a sitting position that allowed free movement of the knee joints. [Results] There was a significant effect of age group on the maximum pelvic anteversion and retroversion angles and pelvic range of motion (the difference between these angles). There was a significant correlation between age and the maximum pelvic anteversion angle, maximum pelvic retroversion angle, and pelvic range of motion. [Conclusion] The maximum pelvic anteversion and retroversion angles and pelvic range of motion were significantly correlated with age. The maximum pelvic anteversion angle and pelvic range of motion were most affected by age. PMID:25540507

Asai, Hitoshi; Tsuchiyama, Hiroyuki; Hatakeyama, Tomoyuki; Inaoka, Pleiades Tiharu; Murata, Kanichirou

2014-01-01

358

Simulations of Seasonal and Latitudinal Variations in Leaf Inclination Angle Distribution: Implications for Remote Sensing  

NASA Technical Reports Server (NTRS)

The leaf inclination angle distribution (LAD) is an important characteristic of vegetation canopy structure affecting light interception within the canopy. However, LADs are difficult and time consuming to measure. To examine possible global patterns of LAD and their implications in remote sensing, a model was developed to predict leaf angles within canopies. Canopies were simulated using the SAIL radiative transfer model combined with a simple photosynthesis model. This model calculated leaf inclination angles for horizontal layers of leaves within the canopy by choosing the leaf inclination angle that maximized production over a day in each layer. LADs were calculated for five latitude bands for spring and summer solar declinations. Three distinct LAD types emerged: tropical, boreal, and an intermediate temperate distribution. In tropical LAD, the upper layers have a leaf angle around 35 with the lower layers having horizontal inclination angles. While the boreal LAD has vertical leaf inclination angles throughout the canopy. The latitude bands where each LAD type occurred changed with the seasons. The different LADs affected the fraction of absorbed photosynthetically active radiation (fAPAR) and Normalized Difference Vegetation Index (NDVI) with similar relationships between fAPAR and leaf area index (LAI), but different relationships between NDVI and LAI for the different LAD types. These differences resulted in significantly different relationships between NDVI and fAPAR for each LAD type. Since leaf inclination angles affect light interception, variations in LAD also affect the estimation of leaf area based on transmittance of light or lidar returns.

Huemmrich, Karl F.

2013-01-01

359

Kinematics of Gait: New Method for Angle Estimation Based on Accelerometers  

PubMed Central

A new method for estimation of angles of leg segments and joints, which uses accelerometer arrays attached to body segments, is described. An array consists of two accelerometers mounted on a rigid rod. The absolute angle of each body segment was determined by band pass filtering of the differences between signals from parallel axes from two accelerometers mounted on the same rod. Joint angles were evaluated by subtracting absolute angles of the neighboring segments. This method eliminates the need for double integration as well as the drift typical for double integration. The efficiency of the algorithm is illustrated by experimental results involving healthy subjects who walked on a treadmill at various speeds, ranging between 0.15 m/s and 2.0 m/s. The validation was performed by comparing the estimated joint angles with the joint angles measured with flexible goniometers. The discrepancies were assessed by the differences between the two sets of data (obtained to be below 6 degrees) and by the Pearson correlation coefficient (greater than 0.97 for the knee angle and greater than 0.85 for the ankle angle). PMID:22346659

Djuri?-Jovi?i?, Milica D.; Jovi?i?, Nenad S.; Popovi?, Dejan B.

2011-01-01

360

An algorithm for selecting the most accurate protocol for contact angle measurement by drop shape analysis.  

PubMed

In this study, an error analysis is performed to study real water drop images and the corresponding numerically generated water drop profiles for three widely used static contact angle algorithms: the circle- and ellipse-fitting algorithms and the axisymmetric drop shape analysis-profile (ADSA-P) algorithm. The results demonstrate the accuracy of the numerically generated drop profiles based on the Laplace equation. A significant number of water drop profiles with different volumes, contact angles, and noise levels are generated, and the influences of the three factors on the accuracies of the three algorithms are systematically investigated. The results reveal that the above-mentioned three algorithms are complementary. In fact, the circle- and ellipse-fitting algorithms show low errors and are highly resistant to noise for water drops with small/medium volumes and contact angles, while for water drop with large volumes and contact angles just the ADSA-P algorithm can meet accuracy requirement. However, this algorithm introduces significant errors in the case of small volumes and contact angles because of its high sensitivity to noise. The critical water drop volumes of the circle- and ellipse-fitting algorithms corresponding to a certain contact angle error are obtained through a significant amount of computation. To improve the precision of the static contact angle measurement, a more accurate algorithm based on a combination of the three algorithms is proposed. Following a systematic investigation, the algorithm selection rule is described in detail, while maintaining the advantages of the three algorithms and overcoming their deficiencies. In general, static contact angles over the entire hydrophobicity range can be accurately evaluated using the proposed algorithm. The ease of erroneous judgment in static contact angle measurements is avoided. The proposed algorithm is validated by a static contact angle evaluation of real and numerically generated water drop images with different hydrophobicity values and volumes. PMID:25554326

Xu, Z N

2014-12-01

361

Gantry-angle resolved VMAT pretreatment verification using EPID image prediction  

SciTech Connect

Purpose: Pretreatment verification of volumetric modulated arc therapy (VMAT) dose delivery with electronic portal imaging device (EPID) uses images integrated over the entire delivery or over large subarcs. This work aims to develop a new method for gantry-angle-resolved verification of VMAT dose delivery using EPID.Methods: An EPID dose prediction model was used to calculate EPID images as a function of gantry angle for eight prostate patient deliveries. EPID image frames at 7.5 frames per second were acquired during delivery via a frame-grabber system. The gantry angle for each image was encoded in kV frames which were synchronized to the MV frames. Gamma analysis results as a function of gantry angle were assessed by integrating the frames over 2° subarcs with an angle-to-agreement tolerance of 0.5° about the measured image angle.Results: The model agreed with EPID images integrated over the entire delivery with average Gamma pass-rates at 2%, 2 mm of 99.7% (10% threshold). The accuracy of the kV derived gantry angle for each image was found to be 0.1° (1 SD) using a phantom test. For the gantry-resolved analysis all Gamma pass-rates were greater than 90% at 3%, 3 mm criteria (with only two exceptions), and more than 90% had a 95% pass-rate, with an average of 97.3%. The measured gantry angle lagged behind the predicted angle by a mean of 0.3°± 0.3°, with a maximum lag of 1.3°.Conclusions: The method provides a comprehensive and highly efficient pretreatment verification of VMAT delivery using EPID. Dose delivery accuracy is assessed as a function of gantry angle to ensure accurate treatment.

Woodruff, Henry C.; Rowshanfarzad, Pejman [School of Mathematical and Physical Sciences, The University of Newcastle, NSW 2308 (Australia)] [School of Mathematical and Physical Sciences, The University of Newcastle, NSW 2308 (Australia); Fuangrod, Todsaporn [School of Electrical Engineering and Computer Science, The University of Newcastle, NSW 2308 (Australia)] [School of Electrical Engineering and Computer Science, The University of Newcastle, NSW 2308 (Australia); McCurdy, Boyd M. C. [Division of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada) [Division of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Department of Radiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Greer, Peter B. [School of Mathematical and Physical Sciences, The University of Newcastle, NSW 2308, Australia and Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Locked Bag 7, Hunter region Mail Centre, Newcastle, NSW 2310 (Australia)] [School of Mathematical and Physical Sciences, The University of Newcastle, NSW 2308, Australia and Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Locked Bag 7, Hunter region Mail Centre, Newcastle, NSW 2310 (Australia)

2013-08-15

362

An algorithm for selecting the most accurate protocol for contact angle measurement by drop shape analysis  

NASA Astrophysics Data System (ADS)

In this study, an error analysis is performed to study real water drop images and the corresponding numerically generated water drop profiles for three widely used static contact angle algorithms: the circle- and ellipse-fitting algorithms and the axisymmetric drop shape analysis-profile (ADSA-P) algorithm. The results demonstrate the accuracy of the numerically generated drop profiles based on the Laplace equation. A significant number of water drop profiles with different volumes, contact angles, and noise levels are generated, and the influences of the three factors on the accuracies of the three algorithms are systematically investigated. The results reveal that the above-mentioned three algorithms are complementary. In fact, the circle- and ellipse-fitting algorithms show low errors and are highly resistant to noise for water drops with small/medium volumes and contact angles, while for water drop with large volumes and contact angles just the ADSA-P algorithm can meet accuracy requirement. However, this algorithm introduces significant errors in the case of small volumes and contact angles because of its high sensitivity to noise. The critical water drop volumes of the circle- and ellipse-fitting algorithms corresponding to a certain contact angle error are obtained through a significant amount of computation. To improve the precision of the static contact angle measurement, a more accurate algorithm based on a combination of the three algorithms is proposed. Following a systematic investigation, the algorithm selection rule is described in detail, while maintaining the advantages of the three algorithms and overcoming their deficiencies. In general, static contact angles over the entire hydrophobicity range can be accurately evaluated using the proposed algorithm. The ease of erroneous judgment in static contact angle measurements is avoided. The proposed algorithm is validated by a static contact angle evaluation of real and numerically generated water drop images with different hydrophobicity values and volumes.

Xu, Z. N.

2014-12-01

363

An Application of Ptolemy's Theorem:Integral triangles with a 120 degree angle and the bisector(of the 120degree angle)also of integral length  

E-print Network

In one of the three 2010/2011 issues of the journal 'MathematicalSpectrum', this author gave a three-parameter description of the entire set of integral triangles(i.e. triangles with integer side lengths)and with a 120 degree angle.This entire set expressed as a union of four families, see reference[5]. In this work we describe, in terms of three parameters again, the set of all integral with a 120 degree angle, and whose bisectors of their 120 degree angles; is also of integral length. To do so, we use the well known historic theorem of Ptolemy for cyclic quadrilaterals, in conjunction with the general positive integer solution of the equation, 1/z=1/x +1/y; and of course in combination with the parametric description of the set of integral triangles with a 120 degree angle mentioned above,The final results of this paper are found in section8.

Konstantine Zelator

2012-03-12

364

An Application of Ptolemy's Theorem:Integral triangles with a 120 degree angle and the bisector(of the 120degree angle)also of integral length  

E-print Network

In one of the three 2010/2011 issues of the journal 'MathematicalSpectrum', this author gave a three-parameter description of the entire set of integral triangles(i.e. triangles with integer side lengths)and with a 120 degree angle.This entire set expressed as a union of four families, see reference[5]. In this work we describe, in terms of three parameters again, the set of all integral with a 120 degree angle, and whose bisectors of their 120 degree angles; is also of integral length. To do so, we use the well known historic theorem of Ptolemy for cyclic quadrilaterals, in conjunction with the general positive integer solution of the equation, 1/z=1/x +1/y; and of course in combination with the parametric description of the set of integral triangles with a 120 degree angle mentioned above,The final results of this paper are found in section8.

Zelator, Konstantine

2012-01-01

365

Joint angles of the ankle, knee, and hip and loading conditions during split squats.  

PubMed

The aim of this study was to quantify how step length and the front tibia angle influence joint angles and loading conditions during the split squat exercise. Eleven subjects performed split squats with an additional load of 25% body weight applied using a barbell. Each subject's movements were recorded using a motion capture system, and the ground reaction force was measured under each foot. The joint angles and loading conditions were calculated using a cluster-based kinematic approach and inverse dynamics modeling respectively. Increases in the tibia angle resulted in a smaller range of motion (ROM) of the front knee and a larger ROM of the rear knee and hip. The external flexion moment in the front knee/hip and the external extension moment in the rear hip decreased as the tibia angle increased. The flexion moment in the rear knee increased as the tibia angle increased. The load distribution between the legs changed < 25% when split squat execution was varied. Our results describing the changes in joint angles and the resulting differences in the moments of the knee and hip will allow coaches and therapists to adapt the split squat exercise to the individual motion and load demands of athletes. PMID:24345718

Schütz, Pascal; List, Renate; Zemp, Roland; Schellenberg, Florian; Taylor, William R; Lorenzetti, Silvio

2014-06-01

366

Bi-anisotropy of multiple-layer fishnet negative-index metamaterials due to angled sidewalls.  

PubMed

Simulation results of near infrared (100- to 200-THz) fishnet-structure negative-index metamaterials (NIMs) with single and multiple functional layers exhibit bi-anisotropy - inhomogeneous asymmetry - due to the presence of a sidewall-angle. The influence of sidewall-angle resulting from realistic fabrication processes is investigated through the retrieved effective parameters by both a three-dimensional finite-difference time-domain (FDTD) method and a rigorous coupled wave analysis (RCWA). PMID:19365507

Ku, Zahyun; Zhang, Jingyu; Brueck, S R J

2009-04-13

367

Material loss angles from direct measurements of broadband thermal noise  

NASA Astrophysics Data System (ADS)

We estimate the loss angles of the materials currently used in the highly reflective test-mass coatings of interferometric detectors of gravitational waves, namely Silica, Tantala, and Ti-doped Tantala, from direct measurement of coating thermal noise in an optical interferometer testbench, the Caltech TNI. We also present a simple predictive theory for the material properties of amorphous glassy oxide mixtures, which gives results in good agreement with our measurements on Ti-doped Tantala. Alternative measurement methods and results are reviewed, and some critical issues are discussed.

Principe, Maria; Pinto, Innocenzo M.; Pierro, Vincenzo; DeSalvo, Riccardo; Taurasi, Ilaria; Villar, Akira E.; Black, Eric D.; Libbrecht, Kenneth G.; Michel, Christophe; Morgado, Nazario; Pinard, Laurent

2015-01-01

368

Material loss angles from direct measurements of broadband thermal noise  

E-print Network

We estimate the loss angles of the materials currently used in the highly reflective test-mass coatings of interferometric detectors of gravitational waves, namely Silica, Tantala, and Ti-dop ed Tantala, from direct measurement of coating thermal noise in an optical interferometer testbench, the Caltech TNI. We also present a simple predictive theory for the material properties of amorphous glassy oxide mixtures, which gives results in good agreement with our measurements on Ti-doped Tantala. Alternative measure ment methods and results are reviewed, and some critical issues are discussed.

Principe, Maria; Pierro, Vincenzo; DeSalvo, Riccardo; Taurasi, Ilaria; Villar, Akira E; Black, Eric D; Libbrecht, Kenneth G; Michel, Christophe; Morgado, Nazario; Pinard, Laurent

2015-01-01

369

Shuttle Program. Euler angles, quaternions, and transformation matrices working relationships  

NASA Technical Reports Server (NTRS)

A brief mathematical development of the relationship between the Euler angles and the transformation matrix, the quaternion and the transformation matrix, and the Euler angles and the quaternion is presented. The analysis and equations presented apply directly to current space shuttle problems. The twelve three-axis Euler transformation matrices are given as functions of the Euler angles, the equations for the quaternion as a funtion of the Euler angles, and the Euler angles as a function of the transformation matrix elements.

Henderson, D. M.

1977-01-01

370

Development of the femoral bicondylar angle in hominid bipedalism  

Microsoft Academic Search

The bicondylar angle is the angle between the diaphysis of the femur and a line perpendicular to the infracondylar plane. The presence of a femoral bicondylar angle in Australopithecus afarensis indicates that these 3.5-million-year-old hominids were bipedal. Many studies have linked the formation of the femoral bicondylar angle with bipedality, but the mechanism for the formation of the angle is

S. J. Shefelbine; C. Tardieu; D. R. Carter

2002-01-01

371

Scatter balance: an angle-based supervised dimensionality reduction.  

PubMed

Subspace selection is widely applied in data classification, clustering, and visualization. The samples projected into subspace can be processed efficiently. In this paper, we research the linear discriminant analysis (LDA) and maximum margin criterion (MMC) algorithms intensively and analyze the effects of scatters to subspace selection. Meanwhile, we point out the boundaries of scatters in LDA and MMC algorithms to illustrate the differences and similarities of subspace selection in different circumstances. Besides, the effects of outlier classes on subspace selection are also analyzed. According to the above analysis, we propose a new subspace selection method called angle linear discriminant embedding (ALDE) on the basis of angle measurement. ALDE utilizes the cosine of the angle to get new within-class and between-class scatter matrices and avoids the small sample size problem simultaneously. To deal with high-dimensional data, we extend ALDE to a two-stage ALDE (TS-ALDE). The synthetic data experiments indicate that ALDE can balance the within-class and between-class scatters and be robust to outlier classes. The experimental results based on UCI machine-learning repository and image databases show that TS-ALDE has a lower time complexity than ALDE while processing high-dimensional data. PMID:25608290

Liu, Shenglan; Feng, Lin; Qiao, Hong

2015-02-01

372

High-angle gravel-pack completion studies  

SciTech Connect

A two-part study was conducted to define optimal gravel-pack procedures for some high-angle well completions in an area operated by Chevron U.S.A. Inc. In the first part of the study, gravel slurries were pumped through a 1,080-ft (329-m) tubing string to simulate actual slurry transport conditions in high-angle wells. The tubing string had an inclination of 80/sup 0/ (1.4 rad) from vertical. Measurements were made to determine suitable viscosity and solids concentration for effective gravel transport. In the second part of the study, a full-scale cased-hole completion model was constructed. Gravel slurries that had satisfactory transport performance were tested for packing characteristics in the model wellbore (completion interval). The need for special completioninterval geometry to obtain satisfactory packs was investigated. Results showed that high-viscosity carrier fluids (600 to 700 cp (0.6 to 0.7 PaXs)) with high gravel concentrations (15 lbm/gal (1797 g/dm/sup 3/)) provide good transport, but they are unsuitable for use in completion intervals in wells with angles of 80/sup 0/ (1.4 rad) from vertical.

Elson, T.D.; Darlington, R.H.; Mantooth, M.A.

1984-01-01

373

Influence of substrate temperature on glancing angle deposited Ag nanorods  

SciTech Connect

When Ag sculptured thin films were grown with glancing angle deposition by ion beam sputtering at either room temperature or elevated substrate temperatures T{sub S}, a large morphological difference was observed. The incident particle flux reached the silicon substrate at a glancing angle {beta}{>=}80 deg. as measured to the substrate normal. A slit aperture was used in order to reduce the particle beam divergence. At room temperature, columnar structures were formed, irrespective of the presence of the slit aperture. At elevated temperatures (573 and 623 K) and collimated particle flux in the presence of the slit aperture, however, enhanced surface diffusion causes the growth of crystalline nanorod- and nanowirelike structures. In the absence of the slit aperture, the flux beam divergence is higher, resulting in island- and mountainlike crystalline structures. The density of the nanorods and nanowires was observed to be higher on the planar Si substrates in comparison to honeycomblike prepatterned substrates with different pattern periods. On the patterned substrates, the nanorods are not necessarily found to be evolving on the seed points but can rather be also observed in-between the artificial seeds. The glancing angle deposited films at high temperatures were observed to be polycrystalline, where the (111) crystal orientation of the film is dominant, while the presence of the less intense (200) reflection was noticed from the x-ray diffraction measurements. In contrast, compact thin films deposited with {beta}{approx_equal}0 deg. at high temperatures were found to be epitaxial with (200) orientation.

Khare, C.; Patzig, C.; Gerlach, J. W.; Rauschenbach, B.; Fuhrmann, B. [Leibniz Institute of Surface Modification, Permoserstrasse 15, 04318 Leipzig (Germany); Interdisciplinary Centre of Materials Science, Martin-Luther-University Halle, Heinrich-Damerow-Strasse 4, 06120 Halle (Germany)

2010-07-15

374

Influence of inflow angle on flexible flap aerodynamic performance  

NASA Astrophysics Data System (ADS)

Large scale wind turbines have larger blade lengths and weights, which creates new challenges for blade design. This paper selects NREL S809 airfoil, and uses the parameterized technology to realize the flexible trailing edge deformation, researches the dynamic aerodynamic characteristics in the process of continuous flexible deformation, analyses the influence of inflow angle on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With inflow angle increases, dynamic lift-drag coefficient hysteresis loop shape deviation occurs, even turns into different shapes. Appropriate swing angle can improve the flap lift coefficient, but may cause early separation of flow. To improve the overall performance of wind turbine blades, different angular control should be used at different cross sections, in order to achieve the best performance.

Y Zhao, H.; Ye, Z.; Li, Z. M.; Li, C.

2013-12-01

375

Elastic impedance variation with angle inversion for elastic parameters  

NASA Astrophysics Data System (ADS)

Elastic impedance (EI) and amplitude variation with offset or angle (AVO/AVA) inversion are two cardinal methods to estimate elastic parameters underground with reflection seismic data. Conventional EI inversion as a kind of pre-stack and post-stack joint inversion method has been widely applied in the industry because of its high efficiency and high stability of wavelet extraction; however, the robustness of extracting elastic parameters in conventional EI inversion is still controversial. The robustness of three-term AVO inversion has improved a lot; however, it is still challenging to extract reasonable space variant wavelets for each offset or incident angle. In this paper, a robust three-parameter estimation method, named elastic impedance variation with angle (EVA) inversion, is proposed in the Bayesian framework, which can estimate elastic parameters directly from EI. This method supposes that the parameters to be inverted are Cauchy distributed and it is implemented based on a normalized EI equation in a logarithmic domain which can reduce the nonlinearity of inversion. Application of a covariance matrix to decorrelate the parameters and constraint of well log curves introduced in an objective function enhances the robustness of EVA inversion. A model test shows that the proposed EVA inversion method enables one to estimate reasonable elastic parameters with extremely smooth initial models and moderate Gaussian noise. A real data example shows that the inverted P-wave velocity, S-wave velocity and density are identical to well log interpretation results, which shows the validity of the proposed method.

Zong, Zhaoyun; Yin, Xingyao; Wu, Guochen

2012-06-01

376

Orbit Propagation Strategies with Angle-Only Observations  

NASA Astrophysics Data System (ADS)

Precise orbit determination and prediction plays an increasingly important role the more dense the population of resident space objects becomes. In this paper different strategies are dis-cussed how to propagate an orbit with angle-only observations. Different orbital regimes are investigated as well as the influence of the temporal spacing of observations. The focus is on objects which do not perform manoeuvres to clearly separate the effects of, probably unavail-able and/or inaccurate, manoeuvre data from modeling the natural forces. Orbit determination and propagation is performed with an enhanced version of the CelMech tool (Beutler, Meth-ods of Celestrical Mechanics, Springer 2001). The ephemerides of the propagated orbits are compared to observations of the same object, which were not used for orbit determination. These additional angle-only observations serve as a ground truth. The data is analyzed with respect to predicted and actually observed covariances. As a reference two line element data (TLEs) of the US Strategic Command (USSTRATCOM) catalogue are propagated with the SDP4 propagator and the resulting ephemerides are compared to the angle-only observations.

Früh, Carolin; Schildknecht, Thomas

377

Sparse Representation Based SAR Vehicle Recognition along with Aspect Angle  

PubMed Central

As a method of representing the test sample with few training samples from an overcomplete dictionary, sparse representation classification (SRC) has attracted much attention in synthetic aperture radar (SAR) automatic target recognition (ATR) recently. In this paper, we develop a novel SAR vehicle recognition method based on sparse representation classification along with aspect information (SRCA), in which the correlation between the vehicle's aspect angle and the sparse representation vector is exploited. The detailed procedure presented in this paper can be summarized as follows. Initially, the sparse representation vector of a test sample is solved by sparse representation algorithm with a principle component analysis (PCA) feature-based dictionary. Then, the coefficient vector is projected onto a sparser one within a certain range of the vehicle's aspect angle. Finally, the vehicle is classified into a certain category that minimizes the reconstruction error with the novel sparse representation vector. Extensive experiments are conducted on the moving and stationary target acquisition and recognition (MSTAR) dataset and the results demonstrate that the proposed method performs robustly under the variations of depression angle and target configurations, as well as incomplete observation. PMID:25161398

Ji, Kefeng; Zou, Huanxin; Sun, Jixiang

2014-01-01

378

Unified Parametrization for Quark and Lepton Mixing Angles  

E-print Network

We propose a new parametrization for the quark and lepton mixing matrices: the two 12-mixing angles (the Cabibbo angle and the angle responsible for solar neutrino oscillations) are at zeroth order pi/12 and pi/5, respectively. The resulting 12-elements in the CKM and PMNS matrices, V_{us} and U_{e2}, are in this order irrational but simple algebraic numbers. We note that the cosine of pi/5 is the golden ratio divided by two. The difference between pi/5 and the observed best-fit value of solar neutrino mixing is of the same order as the difference between the observed value and the one for tri-bimaximal mixing. In order to reproduce the central values of current fits, corrections to the zeroth order expressions are necessary. They are small and of the same order and sign for quarks and leptons. We parametrize the perturbations to the CKM and PMNS matrices in a 'triminimal' way, i.e., with three small rotations in an order corresponding to the order of the rotations in the PDG-description of mixing matrices.

Werner Rodejohann

2008-12-09

379

Low-angle X-ray scattering from spices  

NASA Astrophysics Data System (ADS)

Low-angle scattering of X-rays is characterized by the presence of one or more peaks in the forward direction of scattering. These peaks are due to the interference of photons coherently scattered from the molecules of the medium. Thus these patterns are closely linked to the molecular structure of the investigated medium. In this work, low-angle X-ray scattering (LAXS) profiles of five spices; pimpinella anisum (anise), coriandrum sativum (coriander), cuminum cyminum (cumin), foenculum vulgare (fennel) and nigella sativa (nigella or black cumin) are presented after extensive measurements. It is found that all spices exhibit one characteristic peak at a scattering angle around 10°. This is equivalent to a value x=0.0565 Å -1, where x=sin( ??2)? ?. The full width at half maximum (FWHM) of this peak is found to be characteristic for each type of the investigated spices. The possibility to detect the irradiation of these spices from their LAXS profiles is also examined after 10, 20, 30 and 40 kGy doses of gamma radiation. Except for anise, coriander and cumin at 40 kGy, there are no detectable deviations from the control samples in the scattering profiles of irradiated samples. These results comply with the recommendations of the FDA (US Food and Drug Administration) which defines 30 kGy as the maximum dose for irradiation of spices. The present technique could be used to detect over-irradiation, which causes damage to the molecular structure of some spices.

Desouky, Omar S.; Ashour, Ahmed H.; Abdullah, Mohamed I.; Elshemey, Wael M.

2002-07-01

380

Factors that control the angle of shear bands in geodynamic numerical models of brittle deformation  

NASA Astrophysics Data System (ADS)

Numerical models of brittle deformation on geological timescales typically use a pressure-dependent (Mohr-Coulomb or Drucker-Prager) plastic flow law to simulate plastic failure. Despite its widespread usage in geodynamic models of lithospheric deformation, however, certain aspects of such plasticity models remain poorly understood. One of the most prominent questions in this respect is: what are the factors that control the angle of the resulting shear bands? Recent theoretical work suggest that both Roscoe (45°), Coulomb angles (45 +/- ?/2, where ? is the angle of internal friction) and Arthur angles (45° +/- ( ? + ?/4) where ? is the dilation angle), as well as all intermediate angles are possible. Published numerical models, however, show a large range of shear band angles with some codes favoring Arthur angles, whereas others yield Coulomb angles. In order to understand what causes the differences between the various numerical models, here I perform systematic numerical simulations of shear localization around an inclusion of given length scale. Both numerical (element type), geometrical and rheological (viscoplastic versus viscoelastoplastic) effects are studied. Results indicate that the main factor, controlling shear band angle, is the non-dimensional ratio between the length scale of the heterogeneity d and the size of the numerical mesh ?x. Coulomb angles are observed only in cases where the inclusion is resolved well ( d/ ?x > 5-10), and in which it is located sufficiently far from the boundary of the box. In most other cases, either Arthur or Roscoe orientations are observed. If heterogeneities are one element in size, Coulomb angles are thus unlikely to develop irrespective of the employed numerical resolution. Whereas differences in element types and rheology do have consequences for the maximum obtainable strain rates inside the shear bands, they only have a minor effect on shear band angles. Shear bands, initiated from random noise or from interactions of shear bands with model boundaries or other shear bands, result in stress heterogeneities with dimensionless length scales d/?x ~ 1-2. Such shear bands are thus expected to form Roscoe or Arthur orientations, consistent with the findings in previous numerical models.

Kaus, Boris J. P.

2010-03-01

381

Laser Tracker Calibration - Testing the Angle Measurement System -  

SciTech Connect

Physics experiments at the SLAC National Accelerator Laboratory (SLAC) usually require high accuracy positioning, e. g. 100 {micro}m over a distance of 150 m or 25 {micro}m in a 10 x 10 x 3 meter volume. Laser tracker measurement systems have become one of the most important tools for achieving these accuracies when mapping components. The accuracy of these measurements is related to the manufacturing tolerances of various individual components, the resolutions of measurement systems, the overall precision of the assembly, and how well imperfections can be modeled. As with theodolites and total stations, one can remove the effects of most assembly and calibration errors by measuring targets in both direct and reverse positions and computing the mean to obtain the result. However, this approach does not compensate for errors originating from the encoder system. In order to improve and gain a better understanding of laser tracker angle measurement tolerances we extended our laboratory's capabilities with the addition of a horizontal angle calibration test stand. This setup is based on the use of a high precision rotary table providing an angular accuracy of better than 0.2 arcsec. Presently, our setup permits only tests of the horizontal angle measurement system. A test stand for vertical angle calibration is under construction. Distance measurements (LECOCQ & FUSS, 2000) are compared to an interferometer bench for distances of up to 32 m. Together both tests provide a better understanding of the instrument and how it should be operated. The observations also provide a reasonable estimate of covariance information of the measurements according to their actual performance for network adjustments.

Gassner, Georg; Ruland, Robert; /SLAC

2008-12-05

382

Circular clustering of protein dihedral angles by Minimum Message Length.  

PubMed

Early work on proteins identified the existence of helices and extended sheets in protein secondary structures, a high-level classification which remains popular today. Using the Snob program for information-theoretic Minimum Message Length (MML) classification, we are able to take the protein dihedral angles as determined by X-ray crystallography, and cluster sets of dihedral angles into groups. Previous work by Hunter and States has applied a similar Bayesian classification method, AutoClass, to protein data with site position represented by 3 Cartesian co-ordinates for each of the alpha-Carbon, beta-Carbon and Nitrogen, totalling 9 co-ordinates. By using the von Mises circular distribution in the Snob program, we are instead able to represent local site properties by the two dihedral angles, phi and psi. Since each site can be modelled as having 2 degrees of freedom, this orientation-invariant dihedral angle representation of the data is more compact than that of nine highly-correlated Cartesian co-ordinates. Using the information-theoretic message length concepts discussed in the paper, such a more concise model is more likely to represent the underlying generating process from which the data came. We report on the results of our classification, plotting the classes in (phi, psi) space; and introducing a symmetric information-theoretic distance measure to build a minimum spanning tree between the classes. We also give a transition matrix between the classes and note the existence of three classes in the region phi approximately -1.09 rad and psi approximately -0.75 rad which are close on the spanning tree and have high inter-transition probabilities. This gives rise to a tight, abundant and self-perpetuating structure. PMID:9390236

Dowe, D L; Allison, L; Dix, T I; Hunter, L; Wallace, C S; Edgoose, T

1996-01-01

383

Sun angle, view angle, and background effects on spectral response of simulated balsam fir canopies  

NASA Technical Reports Server (NTRS)

An experiment is described that examines the effects of solar zenith angle and background reflectance on the composite scene reflectance of small balsam fir (Abies balsamea (L.) Mill.) arranged in different densities. In this study, the shape, density, and, consequently, the needle area index and phytomass of the canopies, as well as the background reflectance, were controlled. The effects of sun angle, view angle, and background reflectance on the multispectral response of small balsam fir trees were significant. Regression models relating spectral vegetation indices (i.e., normalized difference (ND) and greenness (GR) to phytomass) showed very poor relationships for balsam fir canopies with a grass background. However, strong linear relationships were found for ND and GR with phytomass for a background that simulated the reflectance of snow. Changing solar zenith angle significantly affected the models relating ND to phytomass for the snow background, but was not significant in the model relating GR to phytomass for the snow background

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

1986-01-01

384

Pitch angle diffusion in the Jovian magnetodisc  

NASA Astrophysics Data System (ADS)

Using a linear approximation to the field variation and a mathematical technique for distorting the orbit integration into the complex gyrophase plane, a formula is derived for the nonadiabatic change in magnetic moment. This change varies as the cosine of the particle gyrophase at the equator, so that if a particle traverses the equator several times with different values of this gyrophase, it suffers randomly correlated values for the nonadiabatic change in magnetic moment. The algebraic formula for this nonadiabatic change is found to be in excellent agreement with previous numerical computations. The phase space density, averaged over several bounce periods, is found to satisfy a diffusion equation in pitch angle. The diffusion coefficient is dependent on particle energy, pitch angle, and the field line along which the particles are moving.

Birmingham, T. J.

1984-05-01

385

Choroid plexus papilloma of the cerebellopontine angle.  

PubMed

The cerebellopontine angle is an extremely rare site for the growth of a choroid plexus papilloma. The clinicoradiological diagnosis of this tumor in the cerebellopontine angle is difficult because of its rarity in addition to a nonspecific clinical presentation and radiological features. Herein, we report the case of a 49-year-old woman with complaints of headache and features of raised intracranial pressure, whose computerized tomography (CT) and magnetic resonance imaging (MRI) were suggestive of acoustic neuroma or meningioma with hydrocephalus. Histology revealed multiple arborizing papillae with a central fibrovascular core, lined by cubo-columnar cells. The cells showed diffuse immunoreactivity for pancytokeratin, S100 protein, synaptophysin, and vimentin, as well as focal expression of glial fibrillary acidic protein, epithelial membrane antigen, and cytokeratin 7. English medical literature is also reviewed. PMID:21039014

Khoddami, Maliheh; Gholampour Shahaboddini, Roohollah

2010-11-01

386

Flow separation in inlets at incidence angles  

NASA Technical Reports Server (NTRS)

Wind-tunnel pressure data and flow pictures obtained for two two-dimensional inlet models have been examined to study the internal flow structure and separation at large incidence angles. The inlet models were 12-in. high (diffuser exit height) and had internal contraction ratio of 1.21 and 1.17. They were tested at low forward speeds over a wide range of throat Mach numbers (inlet mass flow rates) and angles of incidence. Characteristic features of the internal flow such as a drastic change of pressure gradient near the highlight, local separation bubbles and shock/boundary-layer interactions have been indicated and discussed. For a few specific cases, the experimental surface pressure distributions have been compared with theoretical predictions.

Jakubowski, A. K.; Luidens, R. W.

1981-01-01

387

Repellency of the lotus leaf: contact angles, drop retention, and sliding angles.  

PubMed

Much of the modeling done on repellency and super hydrophobicity has focused on surfaces with rectilinear geometries, but their wetting behavior is simpler and can be quite different from that of repellent surfaces with curved features. In this study, we model the contact angles and sliding angles exhibited by the lotus leaf, accounting for the influence of curvature and pinning. Our estimates agree reasonably well with experimental observations. PMID:25029189

Extrand, C W; Moon, Sung In

2014-07-29

388

Measurement of the angle alpha at BABAR  

SciTech Connect

The authors present recent measurements of the CKM angle {alpha} using data collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory, operating at the {Upsilon}(4S) resonance. They present constraints on {alpha} from B {yields} {pi}{pi}, B {yields} {rho}{rho} and B {yields} {rho}{pi} decays.

Perez, A.; /Orsay, LAL

2009-06-25

389

Experimental Aspects Concerning Self-locking Angle  

Microsoft Academic Search

\\u000a Self-locking is a phenomenon that occurs both in lower pairs and higher pairs, being quantified by the self-locking angle;\\u000a it occurs due to friction forces, depending directly on normal forces from mechanism pairs. The paper presents some preliminary\\u000a experimental aspects regarding the influence of different parameters (bushing geometry and material, shaft heat treating,\\u000a gap dimension and friction type, rolling\\/sliding for

S. Alaci; F. C. Ciornei; L. Irimescu; D. Amarandei

390

The Large Angle Spectroscopic Coronagraph (LASCO)  

Microsoft Academic Search

The Large Angle Spectroscopic Coronagraph (LASCO) is a three coronagraph package which has been jointly developed for the Solar and Heliospheric Observatory (SOHO) mission by the Naval Research Laboratory (USA), the Laboratoire d'Astronomie Spatiale (France), the Max-Planck-Institut für Aeronomie (Germany), and the University of Birmingham (UK). LASCO comprises three coronagraphs, C1, C2, and C3, that together image the solar corona

G. E. Brueckner; R. A. Howard; M. J. Koomen; C. M. Korendyke; D. J. Michels; J. D. Moses; D. G. Socker; K. P. Dere; P. L. Lamy; A. Llebaria; M. V. Bout; R. Schwenn; G. M. Simnett; D. K. Bedford; C. J. Eyles

1995-01-01

391

Drop rebound after impact: the role of the receding contact angle.  

PubMed

Data from the literature suggest that the rebound of a drop from a surface can be achieved when the wettability is low, i.e., when contact angles, measured at the triple line (solid-liquid-air), are high. However, no clear criterion exists to predict when a drop will rebound from a surface and which is the key wetting parameter to govern drop rebound (e.g., the "equilibrium" contact angle, ?eq, the advancing and the receding contact angles, ?A and ?R, respectively, the contact angle hysteresis, ??, or any combination of these parameters). To clarify the conditions for drop rebound, we conducted experimental tests on different dry solid surfaces with variable wettability, from hydrophobic to superhydrophobic surfaces, with advancing contact angles 108° < ?A < 169° and receding contact angles 89° < ?R < 161°. It was found that the receding contact angle is the key wetting parameter that influences drop rebound, along with surface hydrophobicity: for the investigated impact conditions (drop diameter 2.4 < D0 < 2.6 mm, impact speed 0.8 < V < 4.1 m/s, Weber number 25 < We < 585), rebound was observed only on surfaces with receding contact angles higher than 100°. Also, the drop rebound time decreased by increasing the receding contact angle. It was also shown that in general care must be taken when using statically defined wetting parameters (such as advancing and receding contact angles) to predict the dynamic behavior of a liquid on a solid surface because the dynamics of the phenomenon may affect surface wetting close to the impact point (e.g., as a result of the transition from the Cassie-Baxter to Wenzel state in the case of the so-called superhydrophobic surfaces) and thus affect the drop rebound. PMID:24028086

Antonini, C; Villa, F; Bernagozzi, I; Amirfazli, A; Marengo, M

2013-12-31

392

Applicability of Washburn capillary rise for determining contact angles of powders/porous materials.  

PubMed

The Washburn capillary rise (WCR) technique has been widely utilized for determining contact angles of powders or porous materials; however, there are concerns regarding powder size and powder packing, especially for materials that exhibit large contact angle hysteresis. In this paper, some of these concerns were addressed. Due to the large water contact angle hysteresis on flat nylon 6/6 films, these films were ground into powders of different sizes and then used as model packing materials. The powders were packed in glass tubes to result in various packing structures that affected the penetration (i.e. advancing) rate of the test liquids. While all advancing contact angles obtained from WCR were found to be overestimated, more reasonable values were resulted when relatively large powders (e.g. 500-2000 ?m) were used to pack the tubes. With larger powders, the packing contained bigger voids and consequently lead to slower penetration rates of the liquids, hence a relatively smaller advancing contact angle. The smaller advancing contact angle obtained from the slower advancing rate was also observed by using the sessile drop method. To verify the applicability of using large powders (500-2000 ?m) for contact angle determination by using WCR, the advancing water contact angles of a bacterial cellulose/alginate composite sponge (BCA) with and without UV/ozone treatment were measured. The results showed that by using relatively large powders, WCR could be applied to obtain a reasonable advancing contact angle and assess the wettability change of complex porous materials. PMID:23484765

Kirdponpattara, Suchata; Phisalaphong, Muenduen; Newby, Bi-min Zhang

2013-05-01

393

The Change in Knee Angle during the Gait by Applying Elastic Tape to the Skin  

PubMed Central

[Purpose] The aim of this study was to verify how the application of elastic tape to the anterior surface of the thigh changes the knee angle pattern during gait. [Subjects] The subjects were 10 people who showed an abnormal knee angle change pattern during usual walking. They did not show the so-called double knee action. [Methods] Subjects were asked to walk as usual, and then to walk with elastic tape attached to the anterior surface of the thigh. The knee angle was measured during gait with an electronic goniometer. We graphed the temporal changes of the knee angle and compared them with the normal gait pattern. [Results] The knee angle gait pattern of six of the 10 subjects improved after application of the tape and became like a normal gait pattern. The changes in the knee angle resulted from a stimulus via the skin, rather than voluntary muscular adjustment, suggesting that the changes may have originated due to differences in reflexive tensile strength. [Conclusion] In normal speed gait, it is suggested that the knee angle was altered such that it exhibited a normal pattern by applying elastic tape to the anterior surface of the thigh. We suspect that application of the elastic tape may change the muscle tonus. PMID:25140100

Yamamoto, Hiroyuki

2014-01-01

394

Does the Panoramic Radiography Have the Power to Identify the Gonial Angle in Orthodontics?  

PubMed Central

Purpose. The objective of this study was to assess gonial angle under the angle classification by comparing panoramic radiograph and lateral cephalometric radiograph. Materials and Methods. 49 patients (25 males, 24 females) with an age range of 12–29 years participated in the present study. Subjects were retrospectively selected among those categorised as skeletal and dental Class I, II, and III malocclusion group. Using lateral cephalometric radiograph, mandibular and ramal planes were drawn and based on these planes. Gonial angle was determined from two tangents which were drawn from the inferior border of the mandible and posterior borders of the condyle and ramus of both sides in the panoramic radiographs. Multiple comparison tests (ANOVA) were used to determine differences between the three angle groups. Results. There were no significant differences between Class I, II, and III malocclusion group values of gonial angles determined by lateral cephalometric radiograph and panoramic radiographs (P > 0.05). Conclusion. Panoramic radiograph results were shown to be as reliable as lateral cephalometric radiograph in all angle classifications. Panoramic radiography can be used as an alternative radiographic technique to detect gonial angle in orthodontic patients. PMID:23365514

Ok?ayan, R?dvan; Aktan, Ali Murat; Sökücü, Oral; Ha?tar, Esin; Ciftci, Mehmet Ertu?rul

2012-01-01

395

Effect of anastomosis angle on hemodynamic of side-to-end radiocephalic arteriovenous fistula (RCAVF)  

NASA Astrophysics Data System (ADS)

Radiocephalic arteriovenous fistula (RCAVF) at wrist is the chosen access for hemodialysis. Most studies describe access complications without considering the effect of the anastomosis angle. In the present investigation, eighteen three-dimensional, simplified models of RCAVF were used to analyze the hemodynamic effect of anastomosis angle under fixed flow rate of 900 ml/min, corresponding to Reynolds number 950. EFD. Lab software was used in the flow simulation with steady flow conditions. The results show that high pressure drop was observed for RCAVF with smaller anastomosis angle. However, for cases with anastomosis angle larger than 45°, pressure drop became relatively constant. The results also show that large vortices appeared in cases with angle smaller than 30°. For cases with angle larger than 60°, low flow zone appeared at the inner wall that may lead to promotion of intimal thickening and formation of stenosis. Overall, for average flowrate, it is recommended that anastomosis angle should be maintained between 45° and 60° to minimize adverse effects.

Hassan, Wan Anuar Wan; Osman, Kahar; Kadir, Mohammed Rafiq Abdul; Abdullah, Wan Ahmad Kamil Wan; Haron, Juhara; Ngali, Mohd Zamani

2012-06-01

396

Measuring the distribution of cellulose microfibril angles in primary cell walls by small angle X-ray scattering  

PubMed Central

Background X-ray scattering is a well-established method for measuring cellulose microfibril angles in secondary cell walls. However, little data is available on the much thinner primary cell walls. Here, we show that microfibril orientation distributions can be determined by small angle X-ray scattering (SAXS) even in primary cell walls. The technique offers a number of advantages: samples can be analyzed in the native hydrated state without any preparation which minimizes the risk of artifacts and allows for fast data acquisition. The method provides data averaged over a specimen region, determined by the size of the used X-ray beam and, thus, yields the microfibril orientation distribution within this region. Results Cellulose microfibril orientation distributions were obtained for single cells of the alga Chara corallina, as well as for the multicellular hypocotyl of Arabidopsis thaliana. In both, Chara and Arabidopsis, distributions with a broad scattering around mean microfibril angles of approximately 0° and 90° towards the longitudinal axis of the cells were found. Conclusions With SAXS, the structure of primary cell walls can be analysed in their native state and new insights into the cellulose microfibril orientation of primary cell walls can be gained. The data shows that SAXS can serve as a valuable tool for the analysis of cellulose microfibril orientation in primary cell walls and, in consequence, add to the understanding of its mechanical behaviour and the intriguing mechanisms behind cell growth. PMID:25170343

2014-01-01

397

The Use of Accelerometers and Gyroscopes to Estimate Hip and Knee Angles on Gait Analysis  

PubMed Central

In this paper the performance of a sensor system, which has been developed to estimate hip and knee angles and the beginning of the gait phase, have been investigated. The sensor system consists of accelerometers and gyroscopes. A new algorithm was developed in order to avoid the error accumulation due to the gyroscopes drift and vibrations due to the ground contact at the beginning of the stance phase. The proposed algorithm have been tested and compared to some existing algorithms on over-ground walking trials with a commercial device for assisted gait. The results have shown the good accuracy of the angles estimation, also in high angle rate movement. PMID:24828578

Alonge, Francesco; Cucco, Elisa; D'Ippolito, Filippo; Pulizzotto, Alessio

2014-01-01

398

On the determination of diffusion lengths by means of angle-lapped p-n junctions  

NASA Technical Reports Server (NTRS)

A standard procedure for determining the minority carrier diffusion length by means of SEM consists of scanning an angle-lapped surface of a p-n junction and measuring the resulting short circuit current as a function of beam position. The present paper points out that the usual expression linking the short circuit current induced by the electron beam to the angle between the semiconductor surface and the junction plane is incorrect. The correct expression is discussed and it is noted that, for angles less than 10 deg, the new and the old expression are practically indistinguishable.

Von Roos, O.

1979-01-01

399

The D.V.L. Gliding-angle Control : W. Hubner Design  

NASA Technical Reports Server (NTRS)

This report describes a device for arbitrary enlargement of the gliding angle of airplanes, especially of such with flat gliding angle and difficult landing characteristics. The D.V.L. gliding angle control (design, Hubner) permits a local interruption of the lift distribution along the span and consequently an increased induced drag. The mechanism comprises two wing rudders operated by lever from the pilot's cockpit. Said rudders are fitted on the top side of the wing near the leading edge. The displacement of these rudders results in a separation of the air flow on the top side of the wing.

Hubner, Walter; Pleines, Wilhelm

1933-01-01

400

Optical search limit and preferred position angles of galaxies in 35 clusters  

NASA Astrophysics Data System (ADS)

We worked on POSSII and ESO films and measured the diameters and position angles of 6244 galaxies in 35 clusters using a 25-fold magnification microscope. The optical search limit has been estimated for these clusters. The position angle distributions of galaxies in the clusters have been studied. For this, chi-square, auto-correlation and the Fourier tests have been carried out. A dependence has been noticed between the optical search limit and the mean radial velocity of the cluster. The preferred position angle distribution of galaxies in the cluster has been found to be independent of the mean radial velocity of the cluster. Possible explanations of the result are discussed.

Aryal, B.; Bachchan, R. K.; Saurer, W.

2010-12-01

401

Performance analysis of first iteration koch curve fractal log periodic antenna of varying flare angles  

NASA Astrophysics Data System (ADS)

Miniaturization has always been a crucial challenge in the field of antenna engineering. In the recent past a number of researchers have shown that fractal geometry have potential to design smaller, broad band and multi band antennas. In this proposed work performances of log periodic fractal antennas of different flare angles have been investigated. Simulation results show that fractal log periodic antenna gives better performance in terms of gain, return loss and directivity. Performance of log periodic fractal antenna has also been investigated for flare angles 30°, 45°, 60°, 70° and 80°. In this proposed work fractal antenna gives best performance with 60° flare angle.

Singh, Ashutosh K.; Kabeer, Reneez A.; Ali, Z.; Singh, V. K.; Shukla, M.

2013-03-01

402

Viewing-angle enhanced computer-generated holographic display system combined with integral imaging  

NASA Astrophysics Data System (ADS)

For large viewing-angle enhancement in three-dimensional (3D) display, a dynamic computer-generated holographic display system combined with integral imaging is proposed and implemented using a single phase-type spatial light modulator and an elemental lens array. For viewing-angle enhanced colorized 3D integral image display the computer-generated holograms have been synthesized and scaled for minimizing the color dispersion error in the hologram plane. Using the integral imaging and synthetic phase holography, we can get 3D images with full parallax and continuously varying viewing-angle range of +/-6 degree. Finally we show some experimental results that verify our concept.

Choi, Kyongsik; Choi, Heejin; Kim, Hwi; Hahn, Joonku; Lim, Yongjun; Kim, Joohwan; Lee, Byoungho

2005-11-01

403

View angle effects in the radiometric measurement of plant canopy temperatures  

NASA Technical Reports Server (NTRS)

The thermal infrared sensor response from a wheat canopy was extremely non-Lambertian because of spatial variations in energy flow processes; the effective radiant temperature of the sensor varied as much as 13 C with changing view angle. This variation of sensor response was accurately quantified (root-mean-square of deviations between theoretical and measured responses reduced to 1.1 C) as a function of vegetation canopy geometry, vertical temperature distribution of canopy components, and sensor view angle. The results have important implications for optimizing sensor view angles for remote sensing missions.

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

1980-01-01

404

Effect of posture on hip angles and moments during gait.  

PubMed

Anterior hip pain is common in young, active adults. Clinically, we have noted that patients with anterior hip pain often walk in a swayback posture, and that their pain is reduced when the posture is corrected. The purpose of this study was to investigate a potential mechanism for the reduction in pain by testing the effect of posture on movement patterns and internal moments during gait in healthy subjects. Fifteen subjects were instructed to walk while maintaining three postures: 1) natural, 2) swayback, and 3) forward flexed. Kinematic and force data were collected using a motion capture system and a force plate. Walking in the swayback posture resulted in a higher peak hip extension angle, hip flexor moment and hip flexion angular impulse compared to natural posture. In contrast, walking in a forward flexed posture resulted in a decreased hip extension angle and decreased hip flexion angular impulse. Based on these results, walking in a swayback posture may result in increased forces required of the anterior hip structures, potentially contributing to anterior hip pain. This study provides a potential biomechanical mechanism for clinical observations that posture correction in patients with hip pain is beneficial. PMID:25262565

Lewis, Cara L; Sahrmann, Shirley A

2015-02-01

405

An improved method for calibrating the gantry angles of linear accelerators.  

PubMed

Linear particle accelerators (linacs) are widely used in radiotherapy procedures; therefore, accurate calibrations of gantry angles must be performed to prevent the exposure of healthy tissue to excessive radiation. One of the common methods for calibrating these angles is the spirit level method. In this study, a new technique for calibrating the gantry angle of a linear accelerator was examined. A cubic phantom was constructed of Styrofoam with small lead balls, embedded at specific locations in this foam block. Several x-ray images were taken of this phantom at various gantry angles using an electronic portal imaging device on the linac. The deviation of the gantry angles were determined by analyzing the images using a customized computer program written in ImageJ (National Institutes of Health). Gantry angles of 0, 90, 180, and 270 degrees were chosen and the results of both calibration methods were compared for each of these angles. The results revealed that the image method was more precise than the spirit level method. For the image method, the average of the measured values for the selected angles of 0, 90, 180, and 270 degrees were found to be -0.086 ± 0.011, 90.018 ± 0.011, 180.178 ± 0.015, and 269.972 ± 0.006 degrees, respectively. The corresponding average values using the spirit level method were 0.2 ± 0.03, 90.2 ± 0.04, 180.1 ± 0.01, and 269.9 ± 0.05 degrees, respectively. Based on these findings, the new method was shown to be a reliable technique for calibrating the gantry angle. PMID:24077078

Higgins, Kyle; Treas, Jared; Jones, Andrew; Fallahian, Naz Afarin; Simpson, David

2013-11-01

406

Long-term evolution of nourished beaches under high angle wave conditions  

NASA Astrophysics Data System (ADS)

A nonlinear numerical model for large-scale dynamics of shoreline and nearshore bathymetry under wave action is applied to investigate the long-term evolution of a rectilinear coast dominated by high angle wave incidence, which is perturbed by a nourishment or an offshore borrow pit. Previous studies show that a coastline can be unstable due to high angle wave instability, which results from the feedback between shoreline changes and the wave field. In contrast to traditional one-line shoreline models, which always predict a diffusional behaviour, this instability can lead to the growth of shoreline perturbations. Model results suggest that due to high angle wave insta