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1

Ray-traced troposphere slant delays for precise point positioning  

NASA Astrophysics Data System (ADS)

Precise satellite orbits and clock information for global navigation satellite systems (GNSS) allow zero-difference position solutions, also known as precise point positioning (PPP) to be calculated. In recent years numerical weather models (NWM) have undergone an improvement of spatial and temporal resolution. This makes them not only useful for the computation of mapping functions but also allows slant troposphere delays from ray-tracing to be obtained. For this study, such ray-traced troposphere corrections have been applied to code and phase observations of 13 sites from the International GNSS Service (IGS) receiver network, which are located inside the boundaries of the Japanese Meteorological Agency (JMA) meso-scale weather model, covering a period of 4 months. The results from this approach are presented together with a comparison to standard PPP processing results. Moreover the advantages and caveats of the introduction of ray-traced slant delays for precise point positioning are discussed.

Hobiger, T.; Ichikawa, R.; Takasu, T.; Koyama, Y.; Kondo, T.

2008-05-01

2

Network based real-time precise point positioning  

NASA Astrophysics Data System (ADS)

Network based real-time precise point positioning system includes two stages, i.e. real-time estimation of satellite clocks based on a reference network and real-time precise point positioning thereafter. In this paper, a satellite- and epoch-differenced approach, adopted from what is introduced by Han et al. (2001), is presented for the determination of satellite clocks and for the precise point positioning. One important refinement of our approach is the implementation of the robust clock estimation. A prototype software system is developed, and data from the European Reference Frame Permanent Network on September 19, 2009 is used to evaluate the approach. Results show that our approach is 3 times and 90 times faster than the epoch-difference approach and the zero-difference approach, respectively, which demonstrates a significant improvement in the computation efficiency. The RMS of the estimated clocks is at the level of 0.1 ns (3 cm) compared to the IGS final clocks. The clocks estimates are then applied to the precise point positioning in both kinematic and static mode. In static mode, the 2-h estimated coordinates have a mean accuracy of 3.08, 5.79, 6.32 cm in the North, East and Up directions. In kinematic mode, the mean kinematic coordinates accuracy is of 4.63, 5.82, 9.20 cm.

Li, Haojun; Chen, Junping; Wang, Jiexian; Hu, Congwei; Liu, Zhiqiang

2010-11-01

3

Precise Point Positioning Based on BDS and GPS Observations  

NASA Astrophysics Data System (ADS)

BeiDou Navigation Satellite System (BDS) has obtained the ability applying initial navigation and precise point services for the Asian-Pacific regions at the end of 2012 with the constellation of 5 Geostationary Earth Orbit (GEO), 5 Inclined Geosynchronous Orbit (IGSO) and 4 Medium Earth Orbit (MEO). Till 2020, it will consist with 5 GEO, 3 IGSO and 27 MEO, and apply global navigation service similar to GPS and GLONASS. As we known, GPS precise point positioning (PPP) is a powerful tool for crustal deformation monitoring, GPS meteorology, orbit determination of low earth orbit satellites, high accuracy kinematic positioning et al. However, it accuracy and convergence time are influenced by the quality of pseudo-range observations and the observing geometry between user and Global navigation satellites system (GNSS) satellites. Usually, it takes more than 30 minutes even hours to obtain centimeter level position accuracy for PPP while using GPS dual-frequency observations only. In recent years, many researches have been done to solve this problem. One of the approaches is smooth pseudo-range by carrier-phase observations to improve pseudo-range accuracy. By which can improve PPP initial position accuracy and shorten PPP convergence time. Another sachems is to change position dilution of precision (PDOP) with multi-GNSS observations. Now, BDS has the ability to service whole Asian-Pacific regions, which make it possible to use GPS and BDS for precise positioning. In addition, according to researches on GNSS PDOP distribution, BDS can improve PDOP obviously. Therefore, it necessary to do some researches on PPP performance using both GPS observations and BDS observations, especially in Asian-Pacific regions currently. In this paper, we focus on the influences of BDS to GPS PPP mainly in three terms including BDS PPP accuracy, PDOP improvement and convergence time of PPP based on GPS and BDS observations. Here, the GPS and BDS two-constellation data are collected from BeiDou experimental tracking stations (BETS) built by Wuhan University. And BDS precise orbit and precise clock products are applied by GNSS center, Wuhan University. After an introduction about GPS+BDS PPP mathematical and the error correction modes, we analyze the influence of BDS to GPS PPP carefully with calculating results. The statistics results show that BDS PPP can reach centimeter level and BDS can improve PDOP obviously. Moreover, the convergence time and position stability of GPS+BDS PPP is better than that of GPS PPP.

Gao, ZhouZheng; Zhang, Hongping; Shen, Wenbin

2014-05-01

4

Assessing the Accuracy of the Precise Point Positioning Technique  

NASA Astrophysics Data System (ADS)

The Precise Point Positioning (PPP) GPS data processing technique has developed over the past 15 years to become a standard method for growing categories of positioning and navigation applications. The technique relies on single receiver point positioning combined with the use of precise satellite orbit and clock information and high-fidelity error modelling. The research presented here uniquely addresses the current accuracy of the technique, explains the limits of performance, and defines paths to improvements. For geodetic purposes, performance refers to daily static position accuracy. PPP processing of over 80 IGS stations over one week results in few millimetre positioning rms error in the north and east components and few centimetres in the vertical (all one sigma values). Larger error statistics for real-time and kinematic processing are also given. GPS PPP with ambiguity resolution processing is also carried out, producing slight improvements over the float solution results. These results are categorised into quality classes in order to analyse the root error causes of the resultant accuracies: "best", "worst", multipath, site displacement effects, satellite availability and geometry, etc. Also of interest in PPP performance is solution convergence period. Static, conventional solutions are slow to converge, with approximately 35 minutes required for 95% of solutions to reach the 20 cm or better horizontal accuracy. Ambiguity resolution can significantly reduce this period without biasing solutions. The definition of a PPP error budget is a complex task even with the resulting numerical assessment, as unlike the epoch-by-epoch processing in the Standard Position Service, PPP processing involving filtering. An attempt is made here to 1) define the magnitude of each error source in terms of range, 2) transform ranging error to position error via Dilution Of Precision (DOP), and 3) scale the DOP through the filtering process. The result is a deeper understanding of how PPP works, rather than just the performance of the technique determined from estimated station coordinates. From the above analysis, the limitations of PPP and the source of these limitations are isolated, including site displacement modelling, geometric measurement strength, pseudorange noise and multipath, etc. It is argued that new ambiguity resolution and multi-GNSS PPP processing will only partially address these limitations. Improved modelling is required for: site displacement effects, pseudorange noise and multipath, and code and phase biases. As well, more robust undifferenced-phase ambiguity validation and overall stochastic modelling is required.

Bisnath, S. B.; Collins, P.; Seepersad, G.

2012-12-01

5

Analysis of Current Position Determination Accuracy in Natural Resources Canada Precise Point Positioning Service  

NASA Astrophysics Data System (ADS)

Precise Point Positioning (PPP) is a technique used to determine highprecision position with a single GNSS receiver. Unlike DGPS or RTK, satellite observations conducted by the PPP technique are not differentiated, therefore they require that parameter models should be used in data processing, such as satellite clock and orbit corrections. Apart from explaining the theory of the PPP technique, this paper describes the available web-based online services used in the post-processing of observation results. The results obtained in the post-processing of satellite observations at three points, with different characteristics of environment conditions, using the CSRS-PPP service, will be presented as the results of the experiment. This study examines the effect of the duration of the measurement session on the results and compares the results obtained by working out observations made by the GPS system and the combined observations from GPS and GLONASS. It also presents the analysis of the position determination accuracy using one and two measurement frequencies

Krzan, Grzegorz; Dawidowicz, Karol; Krzysztof, ?wia?ek

2013-09-01

6

Development of a Real-Time Single-Frequency Precise Point Positioning System and Test Results  

Microsoft Academic Search

Precise Point Positioning (PPP) has received wide attention in the past several years as one of the next generation RTK technologies. PPP can offer great flexibility and cost-saving to field positioning work as it can eliminates the need to deploy base stations. Centimetre to decimetre accurate positioning accuracy has been widely demonstrated for PPP using a dual-frequency GPS receiver. The

Yang Gao; Yufeng Zhang; Kongzhe Chen

2006-01-01

7

Rapid re-convergences to ambiguity-fixed solutions in precise point positioning  

Microsoft Academic Search

Integer ambiguity resolution at a single receiver can be achieved if the fractional-cycle biases are separated from the ambiguity\\u000a estimates in precise point positioning (PPP). Despite the improved positioning accuracy by such integer resolution, the convergence\\u000a to an ambiguity-fixed solution normally requires a few tens of minutes. Even worse, these convergences can repeatedly occur\\u000a on the occasion of loss of

Jianghui Geng; Xiaolin Meng; Alan H. Dodson; Maorong Ge; Felix N. Teferle

2010-01-01

8

Precise Point Positioning for the Efficient and Robust Analysis of GPS Data from Large Networks  

NASA Technical Reports Server (NTRS)

Networks of dozens to hundreds of permanently operating precision Global Positioning System (GPS) receivers are emerging at spatial scales that range from 10(exp 0) to 10(exp 3) km. To keep the computational burden associated with the analysis of such data economically feasible, one approach is to first determine precise GPS satellite positions and clock corrections from a globally distributed network of GPS receivers. Their, data from the local network are analyzed by estimating receiver- specific parameters with receiver-specific data satellite parameters are held fixed at their values determined in the global solution. This "precise point positioning" allows analysis of data from hundreds to thousands of sites every (lay with 40-Mflop computers, with results comparable in quality to the simultaneous analysis of all data. The reference frames for the global and network solutions can be free of distortion imposed by erroneous fiducial constraints on any sites.

Zumberge, J. F.; Heflin, M. B.; Jefferson, D. C.; Watkins, M. M.; Webb, F. H.

1997-01-01

9

Precise Point Positioning for the Efficient and Robust Analysis of GPS Data From Large Networks  

NASA Technical Reports Server (NTRS)

Networks of dozens to hundreds of permanently operating precision Global Positioning System (GPS) receivers are emerging at spatial scales that range from 10(exp 0) to 10(exp 3) km. To keep the computational burden associated with the analysis of such data economically feasible, one approach is to first determine precise GPS satellite positions and clock corrections from a globally distributed network of GPS receivers. Then, data from the local network are analyzed by estimating receiver specific parameters with receiver-specific data; satellite parameters are held fixed at their values determined in the global solution. This "precise point positioning" allows analysis of data from hundreds to thousands of sites every day with 40 Mflop computers, with results comparable in quality to the simultaneous analysis of all data. The reference frames for the global and network solutions can be free of distortion imposed by erroneous fiducial constraints on any sites.

Zumberge, J. F.; Heflin, M. B.; Jefferson, D. C.; Watkins, M. M.; Webb, F. H.

1997-01-01

10

Incorporation of the GPS satellite ephemeris covariance matrix into the precise point positioning  

NASA Astrophysics Data System (ADS)

In GPS positioning, usually the satellite ephemeris are fixed in the observation equations using broadcast or published values. Therefore, to have a realistic covariance matrix for the observations one must incorporate a well-defined covariance matrix of the satellite ephemeris into the observations covariance matrix. Contributions so far have discussed only the variance and covariance of the observations. Precise Point Positioning (PPP) is a technique aimed at processing of measurements from a single (stand-alone) GPS receiver to compute high-accurate position. In this paper, the covariance matrix of the satellite ephemeris and its impact on the position estimates through the PPP are discussed.

Shirazian, Masoud

2013-09-01

11

Real-Time IGS products verification in the context of their use in Precise Point Positioning  

NASA Astrophysics Data System (ADS)

Precise Point Positioning (PPP) is a positioning technique of single GNSS receiver which applies high quality products from permanent GNSS observations to utilize the computational potential of global network analysis. Estimated satellite orbits and clocks corrections are introduced into equation system as known parameters. PPP requires the application of precise products, since their quality directly reflects the positioning accuracy. In June 2007 IGS Real-time Pilot Project has started in order to satisfy real-time users, which is especially important for Precise Point Positioning. Currently available streams including precise orbits, clocks and code biases are standardized on RTCM-SC 104 formats and may be used as a substitute for ultra-rapid products. The target combination product performances are 0.3ns for satellite clock accuracy and orbit accuracy at the level of the IGS Ultra predictions with maximum latency of 10s. This study presents the quality assessment of currently available Real-Time IGS products. Long-term test include comparisons of disseminated information with final and high-rate products, stability assessment over time, as well as latency validation of available RTCM streams.

Hadas, Tomasz; Bosy, Jaroslaw; Kaplon, Jan; Sierny, Jan

2013-04-01

12

Precise Point Positioning technique for short and long baselines time transfer  

NASA Astrophysics Data System (ADS)

In this work the clock parameters determination of several timing receivers TTS-4 (AOS), ASHTECH Z-XII3T (OP, ORB, PTB, USNO) and SEPTENTRIO POLARX4TR (ORB, since February 11, 2012) by use of the Precise Point Positioning (PPP) technique were presented. The clock parameters were determined for several time links based on the data delivered by time and frequency laboratories mentioned above. The computations cover the period from January 1 to December 31, 2012 and were performed in two modes with 7-day and one-month solution for all links. All RINEX data files which include phase and code GPS data were recorded in 30-second intervals. All calculations were performed by means of Natural Resource Canada's GPS Precise Point Positioning (GPS-PPP) software based on high-quality precise satellite coordinates and satellite clock delivered by IGS as the final products. The used independent PPP technique is a very powerful and simple method which allows for better control of antenna positions in AOS and a verification of other time transfer techniques like GPS CV, GLONASS CV and TWSTFT. The PPP technique is also a very good alternative for calibration of a glass fiber link PL-AOS realized at present by AOS. Currently PPP technique is one of the main time transfer methods used at AOS what considerably improve and strengthen the quality of the Polish time scales UTC(AOS), UTC(PL), and TA(PL). KEY-WORDS: Precise Point Positioning, time transfer, IGS products, GNSS, time scales.

Lejba, Pawel; Nawrocki, Jerzy; Lemanski, Dariusz; Foks-Ryznar, Anna; Nogas, Pawel; Dunst, Piotr

2013-04-01

13

The Study on Precise Positioning Method of Autonomous Mobile Robot Based on Three-Point Location Principle  

Microsoft Academic Search

According to the precise positioning needs of the autonomous mobile robot, a three-point precise location measurement method is presented for the mobile robot control. In this location method, the parameters measured on the ultrasonic sensors be re-demarcated and filtered by error threshold under local coordinate system, precise position of mobile robot can be achieved. The performance of three-point precise location

Guo Shuai; Li Guolin; He Yongyi; Li Xianhua

2009-01-01

14

An improved approach to model regional ionosphere and accelerate convergence for precise point positioning  

NASA Astrophysics Data System (ADS)

Given the severe effects of the ionosphere on global navigation satellite system (GNSS) signals, single-frequency (SF) precise point positioning (PPP) users can only achieve decimeter-level positioning results. Ionosphere-free combinations can eliminate the majority of ionospheric delay, but increase observation noise and slow down dual-frequency (DF) PPP convergence. In this paper, we develop a regional ionosphere modeling and rapid convergence approach to improve SF PPP (SFPPP) accuracy and accelerate DF PPP (DFPPP) convergence speed. Instead of area model, ionospheric delay is modeled for each satellite to be used as a priori correction. With the ionospheric, wide-lane uncalibrated phase delay (UPD) and residuals satellite DCBs product, the wide-lane observations for DF users change to be high-precision pseudorange observations. The validation of a continuously operating reference station (CORS) network was analyzed. The experimental results confirm that the approach considerably improves the accuracy of SFPPP. For DF users, convergence time is substantially reduced.

Yao, Yibin; Zhang, Rui; Song, Weiwei; Shi, Chuang; Lou, Yidong

2013-10-01

15

Effect of the 24 September 2011 solar radio burst on precise point positioning service  

NASA Astrophysics Data System (ADS)

intense solar radio burst occurred on 24 September 2011, which affected the tracking of Global Navigation Satellite Systems' (GNSS) signals by receivers located in the sunlit hemisphere of the Earth. This manuscript presents for the first time the impacts of this radio burst on the availability of Fugro's real-time precise point positioning service for GNSS receivers and on the quality of the L band data link used to broadcast this service. During the peak of the radio burst (12:50-13:20 UT), a reduction in the L band signal-to-noise ratio (SNR) is observed. For some receiver locations, a reset in the position filter is observed, which can be either due to the reduction in the L band SNR or the reduction in the number of tracked GNSS satellites. This reset in the position filter is accompanied by degradation in the positioning accuracy, which is also discussed herein.

Sreeja, V.; Aquino, M.; Jong, Kees; Visser, Hans

2014-03-01

16

Further characterization of the time transfer capabilities of precise point positioning (PPP): the Sliding Batch Procedure.  

PubMed

In recent years, many national timing laboratories have installed geodetic Global Positioning System receivers together with their traditional GPS/GLONASS Common View receivers and Two Way Satellite Time and Frequency Transfer equipment. Many of these geodetic receivers operate continuously within the International GNSS Service (IGS), and their data are regularly processed by IGS Analysis Centers. From its global network of over 350 stations and its Analysis Centers, the IGS generates precise combined GPS ephemeredes and station and satellite clock time series referred to the IGS Time Scale. A processing method called Precise Point Positioning (PPP) is in use in the geodetic community allowing precise recovery of GPS antenna position, clock phase, and atmospheric delays by taking advantage of these IGS precise products. Previous assessments, carried out at Istituto Nazionale di Ricerca Metrologica (INRiM; formerly IEN) with a PPP implementation developed at Natural Resources Canada (NRCan), showed PPP clock solutions have better stability over short/medium term than GPS CV and GPS P3 methods and significantly reduce the day-boundary discontinuities when used in multi-day continuous processing, allowing time-limited, campaign-style time-transfer experiments. This paper reports on follow-on work performed at INRiM and NRCan to further characterize and develop the PPP method for time transfer applications, using data from some of the National Metrology Institutes. We develop a processing procedure that takes advantage of the improved stability of the phase-connected multi-day PPP solutions while allowing the generation of continuous clock time series, more applicable to continuous operation/monitoring of timing equipment. PMID:19686979

Guyennon, Nicolas; Cerretto, Giancarlo; Tavella, Patrizia; Lahaye, François

2009-08-01

17

Impact of orbit, clock and EOP errors in GNSS Precise Point Positioning  

NASA Astrophysics Data System (ADS)

Precise point positioning (PPP; [1]) has gained ever-increasing usage in GNSS carrier-phase positioning, navigation and timing (PNT) since its inception in the late 1990s. In this technique, high-precision satellite clocks, satellite ephemerides and earth-orientation parameters (EOPs) are applied as fixed input by the user in order to estimate receiver/location-specific quantities such as antenna coordinates, troposphere delay and receiver-clock corrections. This is in contrast to "network" solutions, in which (typically) less-precise satellite clocks, satellite ephemerides and EOPs are used as input, and in which these parameters are estimated simultaneously with the receiver/location-specific parameters. The primary reason for increased PPP application is that it offers most of the benefits of a network solution with a smaller computing cost. In addition, the software required to do PPP positioning can be simpler than that required for network solutions. Finally, PPP permits high-precision positioning of single or sparsely spaced receivers that may have few or no GNSS satellites in common view. A drawback of PPP is that the accuracy of the results depend directly on the accuracy of the supplied orbits, clocks and EOPs, since these parameters are not adjusted during the processing. In this study, we will examine the impact of orbit, EOP and satellite clock estimates on PPP solutions. Our primary focus will be the impact of these errors on station coordinates; however the study may be extended to error propagation into receiver-clock corrections and/or troposphere estimates if time permits. Study motivation: the United States Naval Observatory (USNO) began testing PPP processing using its own predicted orbits, clocks and EOPs in Summer 2012 [2]. The results of such processing could be useful for real- or near-real-time applications should they meet accuracy/precision requirements. Understanding how errors in satellite clocks, satellite orbits and EOPs propagate into PPP positioning and timing results allows researchers to focus their improvement efforts in areas most in need of attention. The initial study will be conducted using the simulation capabilities of Bernese GPS Software and extended to using real data if time permits. [1] J.F. Zumberge, M.B. Heflin, D.C. Jefferson, M.M. Watkins and F.H. Webb, Precise point positioning for the efficient and robust analysis of GPS data from large networks, J. Geophys. Res., 102(B3), 5005-5017, doi:10.1029/96JB03860, 1997. [2] C. Hackman, S.M. Byram, V.J. Slabinski and J.C. Tracey, Near-real-time and other high-precision GNSS-based orbit/clock/earth-orientation/troposphere parameters available from USNO, Proc. 2012 ION Joint Navigation Conference, 15 pp., in press, 2012.

Hackman, C.

2012-12-01

18

Precise point positioning for the efficient and robust analysis of GPS data from large networks  

Microsoft Academic Search

Networks of dozens to hundreds of permanently operating precision Global Positioning System (GPS) receivers are emerging at spatial scales that range from 100 to 10  km. To keep the computational burden associated with the analysis of such data economically feasible, one approach is to first determine precise GPS satellite positions and clock corrections from a globally distributed network of

J. F. Zumberge; M. B. Heflin; D. C. Jefferson; M. M. Watkins; F. H. Webb

1997-01-01

19

Experience from combination of the GPS and GLONASS observations in the Precise Point Positioning algorithms  

NASA Astrophysics Data System (ADS)

The Precise Point Positioning (PPP) technique using the un-differenced GPS observations and the precise IGS orbits and satellite clock products is recently a frequently used approach for geocentric coordinate determination. Until now, only the GPS observations are used for PPP mainly due to fact, that for the other GNSS the precise satellite clocks were not generally available. Recently the ESOC GLONASS Data Analysis Centre besides the GLONASS orbits provides regularly also the satellite clocks estimates in 5-minute intervals. In the paper will be introduced the model for computing real-valued ambiguities form code and phase GPS and GLONASS un-differenced observations as well as the procedures for reduction of observed GPS and GLONASS ranges. The models for separate GPS and GLONASS coordinates, clocks and troposphere delays estimates are mutually compared. Finally, the combination of GLONASS and GPS un-differenced data will be demonstrated. The role of additional parameters which are necessary to be introduced for combined solution will be investigated. The results from PPP processing based on separated GNSS observations as well as from their combination in joint adjustment will be discussed. All the procedures mentioned are examined by using the software package ABSOLUTE which is developed for the PPP GNSS processing at the Slovak University of Technology in Bratislava.

Hefty, Jan; Gerhatova, Lubomira

2010-05-01

20

Flight Test Evaluation of Precise Point Positioning Techniques Using Optical Ranging  

NASA Astrophysics Data System (ADS)

This article reports on a flight test for the purpose of validating single-vehicle Global Positioning System (GPS) precise point positioning (PPP) of an aircraft using JPL's Global Navigation Satellite System (GNSS)-Inferred Positioning System (GIPSY) software and postprocessed satellite products. The article provides a comparison of a laser ranging device to GPS position estimates relative to a fixed ground station. The range data derived independently from the laser and GPS techniques agree to an average of 6.6 cm (RMS). The flight test was conducted on a Cessna aircraft circling the laser ranging device installed at Table Mountain in Wrightwood, California, at a range of approximately 6 km while the aircraft flew at an altitude of about 4.3 km. An error budget is presented based on the GPS, laser, meteorology, and inertial sensors employed. The survey of the locations of the instruments and associated error is presented. The range error of 6.6 cm RMS is consistent with the error in the instruments and survey.

Williamson, W.; Haines, B.; Wilson, K.; Kovalik, J.; Wright, M.; Meyer, R.; Bar-Sever, Y.

2012-11-01

21

Improving the estimation of fractional-cycle biases for ambiguity resolution in precise point positioning  

NASA Astrophysics Data System (ADS)

Ambiguity resolution dedicated to a single global positioning system (GPS) station can improve the accuracy of precise point positioning. In this process, the estimation accuracy of the narrow-lane fractional-cycle biases (FCBs), which destroy the integer nature of undifferenced ambiguities, is crucial to the ambiguity-fixed positioning accuracy. In this study, we hence propose the improved narrow-lane FCBs derived from an ambiguity-fixed GPS network solution, rather than the original (i.e. previously proposed) FCBs derived from an ambiguity-float network solution. The improved FCBs outperform the original FCBs by ensuring that the resulting ambiguity-fixed daily positions coincide in nature with the state-of-the-art positions generated by the International GNSS Service (IGS). To verify this improvement, 1 year of GPS measurements from about 350 globally distributed stations were processed. We find that the original FCBs differ more from the improved FCBs when fewer stations are involved in the FCB estimation, especially when the number of stations is less than 20. Moreover, when comparing the ambiguity-fixed daily positions with the IGS weekly positions for 248 stations through a Helmert transformation, for the East component, we find that on 359 days of the year the daily RMS of the transformed residuals based on the improved FCBs is smaller by up to 0.8 mm than those based on the original FCBs, and the mean RMS over the year falls evidently from 2.6 to 2.2 mm. Meanwhile, when using the improved rather than the original FCBs, the RMS of the transformed residuals for the East component of 239 stations (i.e. 96.4% of all 248 stations) is clearly reduced by up to 1.6 mm, especially for stations located within a sparse GPS network. Therefore, we suggest that narrow-lane FCBs should be determined with ambiguity-fixed, rather than ambiguity-float, GPS network solutions.

Geng, Jianghui; Shi, Chuang; Ge, Maorong; Dodson, Alan H.; Lou, Yidong; Zhao, Qile; Liu, Jingnan

2012-08-01

22

GPS Seismology: Using Precise Point Positioning for Resolving Surface Wave Displacements from Large Earthquakes  

NASA Astrophysics Data System (ADS)

High-rate continuous GPS data can provide direct, high-quality measurements of surface wave displacements generated by large earthquakes (Larson et al., 2003; Bock et al., 2004; Larson, 2009). To achieve high precision, differential positioning is often used in the GPS analysis strategy with distant reference stations held fixed. In this presentation, we examine the use of the Precise Point Positioning (PPP) technique to estimate epoch-by-epoch positions at single stations. Specifically, we use the PPP software developed by Natural Resources Canada (Heroux and Kouba, 2001) to analyze high-rate (5 Hz) GPS data collected at stations of the Plate Boundary Observatory (PBO) in southern California at the time of the M7.2 El Mayor-Cucapah Earthquake of April 4, 2010. The hypocenter for this earthquake was located in northern Baja California, approximately 50 km south of Mexicali on the US-Mexico border, at a depth of ~10 km. Large horizontal displacements were observed at a number of PBO GPS sites, with the largest peak-to-peak displacements exceeding 90 cm in the east-west component for 10-sec period waves observed at El Centro, CA (P496), located about 70 km northeast of the epicenter. The PPP technique clearly resolved surface waves with 1 to 2 cm amplitudes at sites more than 800 km away from the epicenter, illustrating that surface waves eventually reach even distant reference sites within the period of interest and can thereby introduce artifacts for differential GPS positioning. Fine-tuning of PPP methodology revealed the following: 1) Since the quality of a PPP solution will not be optimal until the carrier phase ambiguities have converged (tens of minutes), it is best to begin the analyses well before the arrival of seismic waves. To reduce computations, the data for this convergence period need not be high-rate; 2) The use of 5-second precise satellite clock sampling instead of the nominal 30-second clock sampling minimized clock interpolation errors and resulted in improved solutions; 3) Allowing some slow variation in the zenith tropospheric delay over periods of minutes appears to improve the vertical component solution. We conclude that high-rate (5 Hz) PPP can augment observations of ground displacements with periods of 1 s or longer at a resolution of 1 to 2 cm at single stations, both in the near and far fields, avoiding potential bias introduced by motions at a reference site. This makes high-rate PPP analysis of GPS data a useful technique for quantifying longer period ground motions of engineering interest.

Dragert, H.; Henton, J. A.; Lahaye, F.; Kouba, J.; Larson, K. M.; Rogers, G. C.

2010-12-01

23

Effects of non-modeled signal biases in multi-GNSS Precise Point Positioning  

NASA Astrophysics Data System (ADS)

Precise Point Positioning (PPP) which is based on processing of un-differenced GNSS phase and code observations using the precise satellites orbits and satellites clocks is suitable for autonomous high quality geocentric coordinate determination without necessity of terrestrial reference sites. Increase of number of broadcasted GNSS signals and the combination of more satellite systems in common adjustment model emphasize the importance of consideration of intra-system and inter-system biases. The complexity of proper bias modeling is underlined by the fact that their origins are both in satellites and receivers. Part of the GNSS signal delays (e.g. system-specific satellite clock offsets, differential code biases, etc.) which are included in global network solution products is modeling predominantly the satellite dependent biases. The multi-GNSS receiver's biases could be evaluated within the individual site processing of un-differenced code and phase observations by addition of set of parameters related to receiver dependent inter-system, inter-code and inter-channel biases. In the paper are presented results of PPP-based estimates of GPS, GLONASS and GIOVE-B inter-system and intra-system biases for several sites with different GNSS instrumentation. Besides the biases estimated as constant parameters during the processed sessions, also the time evolution of the receiver-related biases is considered. All the procedures are examined by using the software package ABSOLUTE developed for the PPP multi-GNSS processing at the Slovak University of Technology in Bratislava.

Hefty, J.; Gerhatova, L.

2012-04-01

24

Precise point positioning using dual-frequency GPS and GLONASS measurements  

NASA Astrophysics Data System (ADS)

This thesis presents a comprehensive study on Precise Point Positioning (PPP) using combined GPS/GLONASS dual frequency code and carrier phase observations. The existing PPP technique is implemented using only GPS measurements, which will be restricted from use in some situations such as in urban canyons and open-pit mine areas due to insufficient satellite number. In addition, the positioning accuracy and convergence time of PPP need to be further improved. A good strategy is to integrate GPS and GLONASS. In this research, a combined GPS/GLONASS traditional PPP model and a combined GPS/GLONASS U of C PPP model are developed, including their functional and stochastic models. The combined GPS and GLONASS PPP models have been implemented in a new version of the P3 software package. The performance of the combined GPS and GLONASS PPP is assessed using static data from IGS tracking network and kinematic data from an experiment. Numerical results indicate that the positioning accuracy and convergence time have a significant improvement after adding GLONASS observations. A further improvement can be expected when a full GLONASS constellation is completed in the near future. The stability of the GPS-GLONASS system time difference is investigated in the thesis. Recommendations for future work are also addressed.

Cai, Changsheng

25

Calibration of regional ionospheric delay with uncombined precise point positioning and accuracy assessment  

NASA Astrophysics Data System (ADS)

A new method for the calibration of regional ionospheric delay based on uncombined precise point positioning (U-PPP) is proposed in this study. The performance of the new method was comparatively validated in terms of its accuracy and robustness with respect to the phase-smoothed pseudorange (PSP) method through two short-baseline experiments. Accuracy of the PPP-derived ionospheric delays was further assessed by interpolating them to a user station to perform single-frequency simulated kinematic PPP. Two 24-hr period datasets of four continuous operation reference system (CORS) stations were analyzed, collected during calm and disturbed ionospheric conditions, respectively. The single-frequency GPS observables from a user station, that were a-priori corrected by the interpolated ionospheric delays, were utilized to implement single-frequency PPP (SF-PPP). The results show that interpolation accuracy is better than 1 dm and, with the proposed method, is less affected by the ionospheric activity; meanwhile, positioning accuracy of SF-PPP was 4~5 cm (horizontal) and better than 1 dm (vertical). For comparison, two reference SF-PPP solutions were also obtained, in which the ionospheric delays are eliminated either by forming semi-combination observations or by using global ionosphere maps (GIM) model values; in both cases the positioning accuracy was only 4~7 dm (horizontal) and 1 m (vertical). These results provide a further demonstration of the performance of PPP-based regional ionospheric calibration in the parameter domain.

Wei, Li; Pengfei, Cheng; Jinzhong, Bei; Hanjiang, Wen; Hua, Wang

2012-08-01

26

Satellite- and Epoch Differenced Precise Point Positioning Based on a Regional Augmentation Network  

PubMed Central

Precise Point Positioning (PPP) has been demonstrated as a simple and effective approach for user positioning. The key issue in PPP is how to shorten convergence time and improve positioning efficiency. Recent researches mainly focus on the ambiguity resolution by correcting residual phase errors at a single station. The success of this approach (referred to hereafter as NORM-PPP) is subject to how rapidly one can fix wide-lane and narrow-lane ambiguities to achieve the first ambiguity-fixed solution. The convergence time of NORM-PPP is receiver type dependent, and normally takes 15–20 min. Different from the general algorithm and theory by which the float ambiguities are estimated and the integer ambiguities are fixed, we concentrate on a differential PPP approach: the satellite- and epoch differenced (SDED) approach. In general, the SDED approach eliminates receiver clocks and ambiguity parameters and thus avoids the complicated residual phase modeling procedure. As a further development of the SDED approach, we use a regional augmentation network to derive tropospheric delay and remaining un-modeled errors at user sites. By adding these corrections and applying the Robust estimation, the weak mathematic properties due to the ED operation is much improved. Implementing this new approach, we need only two epochs of data to achieve PPP positioning converging to centimeter-positioning accuracy. Using seven days of GPS data at six CORS stations in Shanghai, we demonstrate the success rate, defined as the case when three directions converging to desired positioning accuracy of 10 cm, reaches 100% when the interval between the two epochs is longer than 15 min. Comparing the results of 15 min' interval to that of 10 min', it is observed that the position RMS improves from 2.47, 3.95, 5.78 cm to 2.21, 3.93, 4.90 cm in the North, East and Up directions, respectively. Combining the SDED coordinates at the starting point and the ED relative coordinates thereafter, we demonstrate the performance of RTK PPP with standard deviation of 0.80, 1.34, 0.97 cm in the North, East and Up directions.

Li, Haojun; Chen, Junping; Wang, Jiexian; Wu, Bin

2012-01-01

27

Integrity monitoring in real-time precise point positioning in the presence of ionospheric disturbances  

NASA Astrophysics Data System (ADS)

Ionospheric disturbances are characterized as fast and random variability in the ionosphere. Those phenomena are difficult to predict, detect and model. Occurrence of some strong ionospheric disturbances can cause, inter alia degradation and interruption of GNSS signals. Therefore they are especially harmful for real-time applications, as for example Precise Point Positioning (PPP) in real time, where one of the most important requirements is to ensure the high level of reliability. In such applications verification and confirmation of a high trust degree towards the estimated coordinates is a very critical issue. In one of the previous papers (K. Wezka, 2012 -Identification of system performance parameters and their usability) two sets of parameters have been proposed for enhance reliability of the PPP. The first one for data quality control (QC) of the raw GNSS observations and the second one for examination of the quality, robustness and performance of various processing approaches (strategies). To the second group the following parameters has been proposed: accuracy, precision, availability, integrity and convergence time. In consideration of perturbation of GNSS signal resulting from sudden ionospheric disturbances, one of the most important demands is effective autonomous integrity monitoring. The poster presents first preliminary results of the applicability of the proposed parameters in order to ensure the high level of reliability/integrity of GNSS observations and positioning results under the presence of strong ionospheric anomalies. The data-set from continuously operated GNSS station located at high latitude, where ionospheric disturbances occur more frequently, were used for the analysis. Various selected Receiver Autonomous Integrity Monitoring (RAIM) approaches for quality control of the GNSS observables are applied to the data sets recorded under different (low/quite and high) ionospheric activities. Based on those analyses the usability of the proposed parameters is verified.

Wezka, K.; Galas, R.

2013-12-01

28

Employing GPS L5 Carrier-Frequency in Precise Point Positioning  

NASA Astrophysics Data System (ADS)

Justine Spits and Marcelo C. Santos Dept. of Geodesy and Geomatics Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 Tel: (1-506) 453-4698, Email: msantos@unb.ca, jspits@unb.ca Precise Point Positioning (PPP) is a GNSS technique which, in most cases nowadays, makes use of Global Positioning System (GPS) dual-frequency signals. The increasing availability of the new GPS L5 signal brings about the question on how much can PPP benefit if it uses L5 in conjunction with the legacy L1 and L2 signals. This poster discusses this issue. It involves the study of the use of L5 in conjunction with the other GPS signals (L1 and L2) with emphasis on the potentialities associated with the various combinations, such as L1-L5, L2-L5 and L1-L2-L5. These combinations will bring benefits in different ways, for example, for ionospheric delay mitigation, ambiguity resolution, convergence time and accuracy. Simulated L5 data will be used to test the PPP algorithms. Performance will be compared against the current dual-frequency PPP methodology. Justine Spits: Ph.D. (Liège, Belgium); Post-Doctoral Fellow, University of New Brunswick Marcelo. C. Santos: Ph.D. (New Brunswick); Professor, University of New Brunswick

Spits, J.; Santos, M. C.

2012-12-01

29

Errors Analysis in GPS Precise Point Positioning: Impact of Ambiguity Fixing  

NASA Astrophysics Data System (ADS)

GNSS geodetic positioning using the classical double-difference approach may have some limitations. For example, fixing ambiguities can be challenging for long baselines, while processing short baseline only give the relative displacement between the two stations. In this context and thanks to the continuous improvement of IGS GNSS orbit and clock products, the Precise Point Positioning (PPP) technique appears in the literature as a powerful alternative. If all local Earth deformations are correctly taken into account, residuals of position time series may be used to assess the processing quality in terms of receiver performance and environment, constellation orbits and clocks error projection, and processing options pertinence. The main limitation of most of the current PPP processing strategies is that ambiguities can not be fixed to integer values. However, Mercier et al. (2008) demonstrated that GPS satellite “electronic” biases can be a priori identified in such a way that using a consistent set of GPS orbits, clocks and biases, phase ambiguities recover their integer nature. The CNES-CLS IGS Analysis Center is being providing such set of data since August 2010. This study evaluate the performance of PPP in front of the nowadays requirements of geodesy. We processed data from several IGS sites in order to compute coordinate series on a daily basis but also at higher frequencies (down to 30 second interval). We investigated both the impact of the processing batch duration from hours to several days and the cut-off elevation angle. Various spurious “non geophysical” signals (random, periodic, jumps...)appeared in our series. Especially artificial "midnight jumps" when adopting the usual 24-hours batch solutions (when satellite passes were cut at 0h). The impact of fixing ambiguities on PPP solutions has been investigated. We demonstrate that most of the artifacts affecting “floating” PPP solutions disappeared when ambiguities were fixed.

Perosanz, F.; Fund, F.; Mercier, F.; Loyer, S.; Capdeville, H.

2010-12-01

30

Triple-frequency GPS precise point positioning with rapid ambiguity resolution  

NASA Astrophysics Data System (ADS)

At present, reliable ambiguity resolution in real-time GPS precise point positioning (PPP) can only be achieved after an initial observation period of a few tens of minutes. In this study, we propose a method where the incoming triple-frequency GPS signals are exploited to enable rapid convergences to ambiguity-fixed solutions in real-time PPP. Specifically, extra-wide-lane ambiguity resolution can be first achieved almost instantaneously with the Melbourne-Wübbena combination observable on L2 and L5. Then the resultant unambiguous extra-wide-lane carrier-phase is combined with the wide-lane carrier-phase on L1 and L2 to form an ionosphere-free observable with a wavelength of about 3.4 m. Although the noise of this observable is around 100 times the raw carrier-phase noise, its wide-lane ambiguity can still be resolved very efficiently, and the resultant ambiguity-fixed observable can assist much better than pseudorange in speeding up succeeding narrow-lane ambiguity resolution. To validate this method, we use an advanced hardware simulator to generate triple-frequency signals and a high-grade receiver to collect 1-Hz data. When the carrier-phase precisions on L1, L2 and L5 are as poor as 1.5, 6.3 and 1.5 mm, respectively, wide-lane ambiguity resolution can still reach a correctness rate of over 99 % within 20 s. As a result, the correctness rate of narrow-lane ambiguity resolution achieves 99 % within 65 s, in contrast to only 64 % within 150 s in dual-frequency PPP. In addition, we also simulate a multipath-contaminated data set and introduce new ambiguities for all satellites every 120 s. We find that when multipath effects are strong, ambiguity-fixed solutions are achieved at 78 % of all epochs in triple-frequency PPP whilst almost no ambiguities are resolved in dual-frequency PPP. Therefore, we demonstrate that triple-frequency PPP has the potential to achieve ambiguity-fixed solutions within a few minutes, or even shorter if raw carrier-phase precisions are around 1 mm. In either case, we conclude that the efficiency of ambiguity resolution in triple-frequency PPP is much higher than that in dual-frequency PPP.

Geng, Jianghui; Bock, Yehuda

2013-05-01

31

A Comparison of Real-Time Precise Point Positioning Zenith Total Delay Estimates  

NASA Astrophysics Data System (ADS)

The use of observations from Global Navigation Satellite Systems (GNSS) in operational meteorology is increasing worldwide due to the continuous evolution of GNSS. The assimilation of near real-time (NRT) GNSS-derived zenith total delay (ZTD) estimates into local, regional and global scale numerical weather prediction (NWP) models is now in operation at a number of meteorological institutions. The development of NWP models with high update cycles for now-casting and monitoring of extreme weather events in recent years, requires the estimation of ZTD with minimal latencies, i.e. from 5 to 10 minutes, while maintaining an adequate level of accuracy for these. The availability of real-time (RT) observations and products from the IGS RT service and associated analysis centers make it possible to compute precise point positioning (PPP) solutions in RT, which provide ZTD along with position estimates. This study presents a comparison of the RT ZTD estimates from three different PPP software packages (G-Nut/Tefnut, BNC2.7 and PPP-Wizard) to the state-of-the-art IGS Final Troposphere Product employing PPP in the Bernese GPS Software. Overall, the ZTD time series obtained by the software packages agree fairly well with the estimates following the variations of the other solutions, but showing various biases with the reference. After correction of these the RMS differences are at the order of 0.01 m. The application of PPP ambiguity resolution in one solution or the use of different RT product streams shows little impact on the ZTD estimates.

Ahmed, F.; Vaclavovic, P.; Dousa, J.; Teferle, F. N.; Laurichesse, D.; Bingley, R.

2013-12-01

32

Ambiguity resolution in precise point positioning with hourly data for global single receiver  

NASA Astrophysics Data System (ADS)

Integer ambiguity resolution (IAR) can improve precise point positioning (PPP) performance significantly. IAR for PPP became a highlight topic in global positioning system (GPS) community in recent years. More and more researchers focus on this issue. Progress has been made in the latest years. In this paper, we aim at investigating and demonstrating the performance of a global zero-differenced (ZD) PPP IAR service for GPS users by providing routine ZD uncalibrated fractional offsets (UFOs) for wide-lane and narrow-lane. Data sets from all IGS stations collected on DOY 1, 100, 200 and 300 of 2010 are used to validate and demonstrate this global service. Static experiment results show that an accuracy better than 1 cm in horizontal and 1-2 cm in vertical could be achieved in ambiguity-fixed PPP solution with only hourly data. Compared with PPP float solution, an average improvement reaches 58.2% in east, 28.3% in north and 23.8% in vertical for all tested stations. Results of kinematic experiments show that the RMS of kinematic PPP solutions can be improved from 21.6, 16.6 and 37.7 mm to 12.2, 13.3 and 34.3 mm for the fixed solutions in the east, north and vertical components, respectively. Both static and kinematic experiments show that wide-lane and narrow-lane UFO products of all satellites can be generated and provided in a routine way accompanying satellite orbit and clock products for the PPP user anywhere around the world, to obtain accurate and reliable ambiguity-fixed PPP solutions.

Zhang, Xiaohong; Li, Pan; Guo, Fei

2013-01-01

33

Real Time Precise Point Positioning: Preliminary Results for the Brazilian Region  

NASA Astrophysics Data System (ADS)

GNSS positioning can be carried out in relative or absolute approach. In the last years, more attention has been driven to the real time precise point positioning (PPP). To achieve centimeter accuracy with this method in real time it is necessary to have available the satellites precise coordinates as well as satellites clocks corrections. The coordinates can be used from the predicted IGU ephemeris, but the satellites clocks must be estimated in a real time. It can be made from a GNSS network as can be seen from EUREF Permanent Network. The infra-structure to realize the PPP in real time is being available in Brazil through the Brazilian Continuous Monitoring Network (RBMC) together with the Sao Paulo State GNSS network which are transmitting GNSS data using NTRIP (Networked Transport of RTCM via Internet Protocol) caster. Based on this information it was proposed a PhD thesis in the Univ. Estadual Paulista (UNESP) aiming to investigate and develop the methodology to estimate the satellites clocks and realize PPP in real time. Then, software is being developed to process GNSS data in the real time PPP mode. A preliminary version of the software was called PPP_RT and is able to process GNSS code and phase data using precise ephemeris and satellites clocks. The PPP processing can be accomplished considering the absolute satellite antenna Phase Center Variation (PCV), Ocean Tide Loading (OTL), Earth Body Tide, among others. The first order ionospheric effects can be eliminated or minimized by ion-free combination or parameterized in the receiver-satellite direction using a stochastic process, e.g. random walk or white noise. In the case of ionosphere estimation, a pseudo-observable is introduced in the mathematical model for each satellite and the initial value can be computed from Klobuchar model or from Global Ionospheric Map (GIM). The adjustment is realized in the recursive mode and the DIA (Detection Identification and Adaptation) is used for quality control. In this paper our proposition is to present the mathematical models implemented in the PPP_RT software and some proposal to accomplish the PPP in real time as for example using tropospheric model from Brazilian Numerical Weather Forecast Model (BNWFM) and estimating the ionosphere using stochastic process. GPS data sample from the Brazilian region was processed using the PPP_RT software considering periods under low and high ionospheric activities and the results estimating the ionosphere were compared with the ion-free combination. The PPP results also were analyzed considering the strategy of the troposphere estimation, Hopfield model or using the BNWFM. For the troposphere case, the values from BNWFM can reach similar results when estimating the troposphere. For the ionosphere case, the results have shown that ionosphere estimation can improve the time convergence of the PPP processing what is very important for PPP in real time.

Marques, Haroldo; Monico, João.; Hirokazu Shimabukuro, Milton; Aquino, Marcio

2010-05-01

34

Assessment of correct fixing rate for precise point positioning ambiguity resolution on a global scale  

NASA Astrophysics Data System (ADS)

Ambiguity resolution (AR) for a single receiver has been a popular topic in Global Positioning System (GPS) recently. Ambiguity-resolution methods for precise point positioning (PPP) have been well documented in recent years, demonstrating that it can improve the accuracy of PPP. However, users are often concerned about the reliability of ambiguity-fixed PPP solution in practical applications. If ambiguities are fixed to wrong integers, large errors would be introduced into position estimates. In this paper, we aim to assess the correct fixing rate (CFR), i.e., number of ambiguities correctly fixing to the total number of ambiguities correctly and incorrectly fixing, for PPP user ambiguity resolution on a global scale. A practical procedure is presented to evaluate the CFR of PPP user ambiguity resolution. GPS data of the first 3 days in each month of 2010 from about 390 IGS stations are used for experiments. Firstly, we use GPS data collected from about 320 IGS stations to estimate global single-differenced (SD) wide-lane and narrow-lane satellite uncalibrated phase delays (UPDs). The quality of UPDs is evaluated. We found that wide-lane UPD estimates have a rather small standard deviation (Std) between 0.003 and 0.004 cycles while most of Std of narrow-lane estimates are from 0.01 to 0.02 cycles. Secondly, many experiments have been conducted to investigate the CFR of integer ambiguity resolution we can achieve under different conditions, including reference station density, observation session length and the ionospheric activity. The results show that the CFR of PPP can exceed 98.0 % with only 1 h of observations for most user stations. No obvious correlation between the CFR and the reference station density is found. Therefore, nearly homogeneous CFR can be achieved in PPP AR for global users. At user end, higher CFR could be achieved with longer observations. The average CFR for 30-min, 1-h, 2-h and 4-h observation is 92.3, 98.2, 99.5 and 99.7 %, respectively. In order to get acceptable CFR, 1 h is a recommended minimum observation time. Furthermore, the CFR of PPP can be affected by diurnal variation and geomagnetic latitude variation in the ionosphere. During one day at the hours when rapid ionospheric variations occur or in low geomagnetic latitude regions where equatorial electron density irregularities are produced relatively frequently, a significant degradation of the CFR is demonstrated.

Zhang, Xiaohong; Li, Pan

2013-06-01

35

A closer look at the concept of regional clocks for Precise Point Positioning  

NASA Astrophysics Data System (ADS)

Under the precondition of at least two successfully tracked signals at different carrier frequencies we may obtain their ionosphere free linear combination. By introducing approximate values for geometric effects like orbits and tropospheric delay as well as an initial bias parameter N per individual satellite we can solve for the satellite clock with respect to the receiver clock. Noting, that residual effects like orbit errors, remaining tropospheric delays and a residual bias parameter map into these parameters, this procedure leaves us with a kind of virtual clock differences. These clocks cover regional effects and are therefore clearly correlated with clocks at nearby station. Therefore we call these clock differences, which are clearly different from clock solutions provided for instance by IGS, the "regional clocks". When introducing the regional clocks obtained from real-time data of a GNSS reference station network we are able to process the coordinates of a nearby isolated station via a PPP .In terms of PPP-convergence time which will be reduced down to 30 minutes or less, this procedure is clearly favorable. The accuracy is quite comparable with state of the art PPP procedures. Nevertheless, this approach cannot compete in fixing times with double-difference approaches but the correlation holds over hundreds of kilometers distance to our master station and the clock differences can easily by obtained, even in real-time. This presentation provides preliminary results of the project RA-PPP. RA-PPP is a research project financed by the Federal Ministry for Transport, Innovation and Technology, managed by the Austrian Research Promotion Agency (FFG) in the course of the 6th call of the Austrian Space Application Program (ASAP). RA-PPP stands for Rapid Precise Point Positioning, which denotes the wish for faster and more accurate algorithms for PPP. The concept of regional clocks which will be demonstrated in detail in this presentation is one out of 4 concepts to be evaluated in this project.

Weber, Robert; Karabatic, Ana; Thaler, Gottfried; Abart, Christoph; Huber, Katrin

2010-05-01

36

On the Convergence of Ionospheric Constrained Precise Point Positioning (IC-PPP) Based on Undifferential Uncombined Raw GNSS Observations  

PubMed Central

Precise Point Positioning (PPP) has become a very hot topic in GNSS research and applications. However, it usually takes about several tens of minutes in order to obtain positions with better than 10 cm accuracy. This prevents PPP from being widely used in real-time kinematic positioning services, therefore, a large effort has been made to tackle the convergence problem. One of the recent approaches is the ionospheric delay constrained precise point positioning (IC-PPP) that uses the spatial and temporal characteristics of ionospheric delays and also delays from an a priori model. In this paper, the impact of the quality of ionospheric models on the convergence of IC-PPP is evaluated using the IGS global ionospheric map (GIM) updated every two hours and a regional satellite-specific correction model. Furthermore, the effect of the receiver differential code bias (DCB) is investigated by comparing the convergence time for IC-PPP with and without estimation of the DCB parameter. From the result of processing a large amount of data, on the one hand, the quality of the a priori ionosphere delays plays a very important role in IC-PPP convergence. Generally, regional dense GNSS networks can provide more precise ionosphere delays than GIM and can consequently reduce the convergence time. On the other hand, ignoring the receiver DCB may considerably extend its convergence, and the larger the DCB, the longer the convergence time. Estimating receiver DCB in IC-PPP is a proper way to overcome this problem. Therefore, current IC-PPP should be enhanced by estimating receiver DCB and employing regional satellite-specific ionospheric correction models in order to speed up its convergence for more practical applications.

Zhang, Hongping; Gao, Zhouzheng; Ge, Maorong; Niu, Xiaoji; Huang, Ling; Tu, Rui; Li, Xingxing

2013-01-01

37

On the convergence of ionospheric constrained precise point positioning (IC-PPP) based on undifferential uncombined raw GNSS observations.  

PubMed

Precise Point Positioning (PPP) has become a very hot topic in GNSS research and applications. However, it usually takes about several tens of minutes in order to obtain positions with better than 10 cm accuracy. This prevents PPP from being widely used in real-time kinematic positioning services, therefore, a large effort has been made to tackle the convergence problem. One of the recent approaches is the ionospheric delay constrained precise point positioning (IC-PPP) that uses the spatial and temporal characteristics of ionospheric delays and also delays from an a priori model. In this paper, the impact of the quality of ionospheric models on the convergence of IC-PPP is evaluated using the IGS global ionospheric map (GIM) updated every two hours and a regional satellite-specific correction model. Furthermore, the effect of the receiver differential code bias (DCB) is investigated by comparing the convergence time for IC-PPP with and without estimation of the DCB parameter. From the result of processing a large amount of data, on the one hand, the quality of the a priori ionosphere delays plays a very important role in IC-PPP convergence. Generally, regional dense GNSS networks can provide more precise ionosphere delays than GIM and can consequently reduce the convergence time. On the other hand, ignoring the receiver DCB may considerably extend its convergence, and the larger the DCB, the longer the convergence time. Estimating receiver DCB in IC-PPP is a proper way to overcome this problem. Therefore, current IC-PPP should be enhanced by estimating receiver DCB and employing regional satellite-specific ionospheric correction models in order to speed up its convergence for more practical applications. PMID:24253190

Zhang, Hongping; Gao, Zhouzheng; Ge, Maorong; Niu, Xiaoji; Huang, Ling; Tu, Rui; Li, Xingxing

2013-01-01

38

Real-time GPS sensing of atmospheric water vapor: Precise point positioning with orbit, clock, and phase delay corrections  

NASA Astrophysics Data System (ADS)

recent development of the International Global Navigation Satellite Systems Service Real-Time Pilot Project and the enormous progress in precise point positioning (PPP) techniques provide a promising opportunity for real-time determination of Integrated Water Vapor (IWV) using GPS ground networks for various geodetic and meteorological applications. In this study, we develop a new real-time GPS water vapor processing system based on the PPP ambiguity fixing technique with real-time satellite orbit, clock, and phase delay corrections. We demonstrate the performance of the new real-time water vapor estimates using the currently operationally used near-real-time GPS atmospheric data and collocated microwave radiometer measurements as an independent reference. The results show that an accuracy of 1.0 ~ 2.0 mm is achievable for the new real-time GPS based IWV value. Data of such accuracy might be highly valuable for time-critical geodetic (positioning) and meteorological applications.

Li, Xingxing; Dick, Galina; Ge, Maorong; Heise, Stefan; Wickert, Jens; Bender, Michael

2014-05-01

39

Near real-time and real-time GNSS Precise Point Positioning with external a priori troposphere models  

NASA Astrophysics Data System (ADS)

Precise Point Positioning (PPP) is a positioning technique that uses a single GNSS (Global Navigation Satellite System) receiver that requires external information from analysis of global GNSS permanent network, in particular precise orbits and satellite clocks. This technique is commonly used in post-processing mode and gives results comparable to relative positioning. A shortcoming of this technique is the time required for the solution to converge, which is a main limitation for near real-time and real-time applications. The convergence time depends on the quality of GNSS data, on the accuracy of the a priori parameters and on fast ambiguity resolution. Until recently, near real-time and real-time users were limited in the sources of precise products, since only the predicted part of the ultra-rapid products were available. In 2012, the International GNSS Service (IGS) launched the Real-Time Service (RTS), making available a dedicated set of real-time products, known as IGS-RTS. Nevertheless, there is still no standard procedure for handling the troposphere delay. The a priori troposphere delay, as well as mapping functions, has to be derived from an external source and the adjustment model should account for the correction to an apriori value of the delay. Currently, a number of empirical troposphere state models and mapping functions are available for users in real-time. Near-real time model of troposphere delay can also be determined from the analysis of regional GNSS permanent network. In this paper, we make use of the IGS-RTS along with a number of a priori tropospheric models in order the assess how they influence convergence time and estimated position. For this purpose, we use GPS Analysis and Positioning Software (GAPS) for near-real time processing and GNSS-Wroclaw Algorithms for Real-time Positioning (GNSS-WARP) software for real-time processing of GPS only data together with IGS-RTS precise orbits and satellite clocks. As a priori troposphere model we used GPT together with the Saastamoinen formula, UNB3 model and regional near-real time troposphere model from the analysis of a network of permanent GNSS stations. We combine these models with Niell and VMF mapping functions to compute slant troposphere delays, including those of low-elevation satellites.

Hadas, Tomasz; Santos, Marcelo; Garcia, Alex; Bosy, Jaroslaw; Kaplon, Jan

2014-05-01

40

Estimation of precipitable water vapour using kinematic GNSS precise point positioning over an altitude range of 1 km  

NASA Astrophysics Data System (ADS)

The estimation of total precipitable water vapour (PWV) using kinematic GNSS has been investigated since around 2001, aiming to extend the use of static ground-based GNSS, from which PWV estimates are now operationally assimilated into numerical weather prediction models. To date, kinematic GNSS PWV studies suggest a PWV measurement agreement with radiosondes of 2-3 mm, almost commensurate with static GNSS measurement accuracy, but only shipborne experiments have so far been carried out. As a first step towards extending such sea level-based studies to platforms that operate at a range of altitudes, such as airplanes or land based vehicles, the kinematic GNSS estimation of PWV over an exactly repeated trajectory is considered. A data set was collected from a GNSS receiver and antenna mounted on a carriage of the Snowdon Mountain Railway, UK, which continually ascends and descends through 950 m of vertical relief. Static GNSS reference receivers were installed at the top and bottom of the altitude profile, and derived zenith wet delay (ZWD) was interpolated to the altitude of the train to provide reference values together with profile estimates from the 100 m resolution runs of the Met Office's Unified Model. We demonstrate similar GNSS accuracies as obtained from previous shipborne studies, namely a double difference relative kinematic GNSS ZWD accuracy within 14 mm, and a kinematic GNSS precise point positioning ZWD accuracy within 15 mm. The latter is a more typical airborne PWV estimation scenario i.e. without the reliance on ground-based GNSS reference stations. We show that the kinematic GPS-only precise point positioning ZWD estimation is enhanced by also incorporating GLONASS observations.

Webb, S. R.; Penna, N. T.; Clarke, P. J.; Webster, S.; Martin, I.

2013-12-01

41

Impact of mapping functions based on spherical, ellipsoidal, gradient, and 3d atmospheric structures on GPS Precise Point Positioning  

NASA Astrophysics Data System (ADS)

We evaluate the impact of mapping functions developed from different atmospheric structures on precise point positioning. In each case the atmospheric structure is derived from the same Numerical Weather Model (NWM). We compared five different structures -- from simpler to more realistic: spherical concentric, spherical osculating, ellipsoidal, gradient, and 3D -- and a state-of-art mapping function, Vienna Mapping Functions Site (VMF1). We used data from IGS station ALGO. Results correspond to comparisons with the IGS (non- cumulative) weekly solution. The spherical concentric model shows a large (cm-level) bias in the north component. The spherical osculating (and ellipsoidal) model shows an improvement in the up component, by almost one order of magnitude, over that of VMF1. The 3D atmosphere model reduces the horizontal bias to less than 1 mm, but there is no apparent improvement in the vertical position, which we attribute to unaccounted non-tidal atmospheric pressure loading. Finally, the gradient atmosphere shows biases with magnitude in between those of the spherical osculating and 3d models.

Nievinski, F. G.; Santos, M. C.

2008-12-01

42

Impact of ambiguity resolution and application of transformation parameters obtained by regional GNSS network in Precise Point Positioning  

NASA Astrophysics Data System (ADS)

Precise Point Positioning (PPP) is one of the possible approaches for GNSS data processing. As known this technique is faster and more flexible compared to the others which are based on a differenced approach and constitute a reliable methods for accurate positioning of remote GNSS stations, even in some remote area such as Antarctica. Until few years ago one of the major limits of the method was the impossibility to resolve the ambiguity as integer but nowadays many methods are available to resolve this aspect. The first software package permitting a PPP solution was the GIPSY OASIS realized, developed and maintained by JPL (NASA). JPL produce also orbits and files ready to be used with GIPSY. Recently, using these products came possible to resolve ambiguities improving the stability of solutions. PPP permit to estimate position into the reference frame of the orbits (IGS) and when coordinate in others reference frames, such al ITRF, are needed is necessary to apply a transformation. Within his products JPL offer, for each day, a global 7 parameter transformation that permit to locate the survey into the ITRF RF. In some cases it's also possible to create a costumed process and obtain analogous parameters using local/regional reference network of stations which coordinates are available also in the desired reference frame. In this work some tests on accuracy has been carried out comparing different PPP solutions obtained using the same software packages (GIPSY) but considering the ambiguity resolution, the global and regional transformation parameters. In particular two test area have been considered, first one located in Antarctica and the second one in Italy. Aim of the work is the evaluation of the impact of ambiguity resolution and the use of local/regional transformation parameter in the final solutions. Tests shown how the ambiguity resolution improve the precision, especially in the EAST component with a scattering reduction about 8%. And the use of global transformation parameter permit to improve the accuracy of about 59%, 63% and 29% in the three components N E U, but other tests shown how is possible to improve the accuracy of 67% 71% and 53% using regional transformation parameters. Example of the impact of global vs regional parameters transformation in a GPS time series

Gandolfi, S.; Poluzzi, L.; Tavasci, L.

2012-12-01

43

Ambiguity-fixed GPS precise point positioning for earthquake and tsunami early warning in Western North America  

NASA Astrophysics Data System (ADS)

The development of single-receiver integer ambiguity resolution in recent years has made the GPS precise point positioning (PPP) technique a valuable tool in measuring centimeter-level displacements epoch by epoch at a single station. A good application for this technique is identifying ground motions in an earthquake and tsunami early warning system. With a single receiver, PPP with ambiguity resolution can reproduce the positioning accuracy of conventional differential positioning techniques, but does not depend on any nearby reference stations which may also be displaced during an earthquake. As a result, the PPP data processing is more straightforward and efficient, suggesting that onsite displacement estimation can be carried out semi-autonomously at each GPS station and only a small amount of data, i.e. 3D displacements rather than raw measurements in the differential positioning, need to be transmitted to warning centers. Due to these merits and as part of a NASA-sponsored research effort, we have developed an operational real-time PPP system for Western North America, a vast region of tectonic deformation and significant seismic risk. A group of about 75 real-time GPS stations throughout North America and located far from western US coast (>300 km) is employed to estimate satellite-specific corrections (i.e. satellite clocks and fractional-cycle biases) with the predicted satellite orbits provided by the IGS (International GNSS Services). We note that our PPP implementation is challenged by geophysical constraints in North America and so all clients in the zone of deformation are outside the coverage of the reference network, and thus measurement errors originating in the atmosphere, satellite orbits and clocks are less correlated between the reference stations and the PPP clients. Despite this difficulty, the horizontal positioning accuracy at each PPP station is around 1 cm while the vertical better than 5 cm. This accuracy is sufficient to optimally combine the 1-Hz PPP-derived displacements with collocated (100 Hz) accelerometer data using a Kalman filter to estimate total displacement waveforms with millimeter-level accuracy. We also report on the testing of our approach in a simulated real-time environment for the 2006 Mw 6.0 Parkfield and 2010 Mw 7.2 El Mayor-Cucapah earthquakes.

Geng, J.; Bock, Y.; Fang, P.; Haase, J. S.

2012-12-01

44

Rapid earthquake magnitude from real-time GPS precise point positioning for earthquake early warning and emergency response  

NASA Astrophysics Data System (ADS)

For earthquake early warning (EEW) and emergency response, earthquake magnitude is the crucial parameter to be determined rapidly and correctly. However, a reliable and rapid measurement of the magnitude of an earthquake is a challenging problem, especially for large earthquakes (M>8). Here, the magnitude is determined based on the GPS displacement waveform derived from real-time precise point positioning (PPP). The real-time PPP results are evaluated with an accuracy of 1 cm in the horizontal components and 2-3 cm in the vertical components, indicating that the real-time PPP is capable of detecting seismic waves with amplitude of 1cm horizontally and 2-3cm vertically with a confidence level of 95%. In order to estimate the magnitude, the unique information provided by the GPS displacement waveform is the horizontal peak displacement amplitude. We show that the empirical relation of Gutenberg (1945) between peak displacement and magnitude holds up to nearly magnitude 9.0 when displacements are measured with GPS. We tested the proposed method for three large earthquakes. For the 2010 Mw 7.2 El Mayor-Cucapah earthquake, our method provides a magnitude of M7.18±0.18. For the 2011 Mw 9.0 Tohoku-oki earthquake the estimated magnitude is M8.74±0.06, and for the 2010 Mw 8.8 Maule earthquake the value is M8.7±0.1 after excluding some near-field stations. We therefore conclude that depending on the availability of high-rate GPS observations, a robust value of magnitude up to 9.0 for a point source earthquake can be estimated within 10s of seconds or a few minutes after an event using a few GPS stations close to the epicenter. The rapid magnitude could be as a pre-requisite for tsunami early warning, fast source inversion, and emergency response is feasible.

Fang, Rongxin; Shi, Chuang; Song, Weiwei; Wang, Guangxing; Liu, Jingnan

2014-05-01

45

A method for improving uncalibrated phase delay estimation and ambiguity-fixing in real-time precise point positioning  

NASA Astrophysics Data System (ADS)

In order to improve the performance of precise point positioning (PPP), this paper presents a new data processing scheme to shorten the convergence time and the observation time required for a reliable ambiguity-fixing. In the new scheme, L1 and L2 raw observations are used and the slant ionospheric delays are treated as unknown parameters. The empirical spatial and temporal constraints and the ionospheric delays derived from a real-time available ionospheric model are all considered as pseudo-observations into the estimation for strengthening the solution. Furthermore, we develop a real-time computational procedure for generating uncalibrated phase delays (UPDs) on L1 and L2 frequencies. The PPP solution is first carried out on all reference stations based on the proposed scheme, undifferenced float ambiguities on L1 and L2 frequencies can be directly obtained from the new scheme. The L1 and L2 UPDs are then generated and broadcasted to users in real-time. This data product and also the performance of the new PPP scheme are evaluated. Our results indicate that the new processing scheme considering ionospheric characteristics can reduce the convergence time by about 30 % for float kinematic solutions. The observation time for a reliable ambiguity-fixing is shortened by 25 % compared to that of the traditional ambiguity-fixed kinematic solution. When the new method is used for static reference stations, the observation time for ambiguity-fixing is about 10 min in static mode and only 5 min if the coordinates are fixed to well-known values.

Li, Xingxing; Ge, Maorong; Zhang, Hongping; Wickert, Jens

2013-05-01

46

GPS single frequency precise orbit determination of LEO satellites with the cm-level accuracy and comparison with the precise point positioning  

NASA Astrophysics Data System (ADS)

Using single frequency GPS measurements from the CHAMP satellite it was demonstrated before that during the solar maximum the LEO orbit can be determined with an accuracy below 10 cm RMS (1D). The first order ionosphere effect is removed by linear combination of pseudorange and carrier phase measurements using the so-called LP linear combination. The main limitation of this POD approach is the high noise of the pseudorange measurements. By forming the LP linear combination, noise in the pseudorange measurements is reduced by 50%, and by estimating half-cycle phase ambiguities an additional reduction can be expected in all systematic effects (e.g. multipath, group delay variations, etc.). Furthermore, thanks to the high quality GPS measurements from the GRACE mission, it was demonstrated that the orbit of a LEO satellite can be determined using single frequency measurements with an accuracy of 5 cm RMS (1D). This is very close to the cm-level accuracy of the LEO orbits based on dual-frequency carrier phase measurements. Here we show that based on the latest gravity field models short term perturbations can very accurately be modelled in the numerical integration, considerably reducing the number of empirical parameters. This allows to average errors in the pseudorange measurements over a longer period of time and further increase the accuracy of GRACE orbit down to 3 cm RMS (1D) and beyond. However, at this level of accuracy systematic errors in the code to carrier coherence play a crucial role, especially in terms of signal group delay variations of GPS satellite and LEO antenna. Here we demonstrate a novel approach in the code to carrier calibration based on a geometry and ionosphere free linear combination. We show that it is possible to separate the group delay variations of the GPS satellite antenna from the group delay variations of a LEO or a ground antenna. This leads to very accurate mean group delay maps of the GPS satellite antennas. Validation of the code to carrier coherence calibration is carried out with the independent measurements from a high-gain steerable ground antenna. Here we show how code to phase coherence calibration improves LEO orbit determination based on single frequency measurements and compare our results with the ground precise point positioning based on single-frequency GPS measurements. A typical performance curve relating convergence time and accuracy is derived for PPP, as well as POD of the GRACE satellites during the solar minimum and maximum.

Svehla, Drazen; Escobar, Diego A.; Dow, John M.

47

Ultra-precision positioning assembly  

DOEpatents

An apparatus and method is disclosed for ultra-precision positioning. A slide base provides a foundational support. A slide plate moves with respect to the slide base along a first geometric axis. Either a ball-screw or a piezoelectric actuator working separate or in conjunction displaces the slide plate with respect to the slide base along the first geometric axis. A linking device directs a primary force vector into a center-line of the ball-screw. The linking device consists of a first link which directs a first portion of the primary force vector to an apex point, located along the center-line of the ball-screw, and a second link for directing a second portion of the primary force vector to the apex point. A set of rails, oriented substantially parallel to the center-line of the ball-screw, direct movement of the slide plate with respect to the slide base along the first geometric axis and are positioned such that the apex point falls within a geometric plane formed by the rails. The slide base, the slide plate, the ball-screw, and the linking device together form a slide assembly. Multiple slide assemblies can be distributed about a platform. In such a configuration, the platform may be raised and lowered, or tipped and tilted by jointly or independently displacing the slide plates.

Montesanti, Richard C. (San Francisco, CA); Locke, Stanley F. (Livermore, CA); Thompson, Samuel L. (Pleasanton, CA)

2002-01-01

48

Real-time high-rate co-seismic displacement from ambiguity-fixed precise point positioning: Application to earthquake early warning  

NASA Astrophysics Data System (ADS)

Abstract<p label="1">Nowadays more and more high-rate real-time GPS data become available that provide a great opportunity to contribute to earthquake early warning (EEW) system in terms of capturing regional surface displacements, as an independent information source, useful for promptly estimating the magnitude of large destructive earthquake. In our study, we demonstrate the performance of the real-time ambiguity-fixed <span class="hlt">precise</span> <span class="hlt">point</span> <span class="hlt">positioning</span> (PPP) approach using 5 Hz GPS data collected during El Mayor-Cucapah earthquake (Mw 7.2, 4 April 2010). The PPP-based displacements show to agree with accelerometer-based displacement at centimeter level. The key for successfully obtaining high <span class="hlt">precision</span> displacements is the efficient ambiguity resolution. PPP with ambiguity fixing can result in correct permanent co-seismic offsets and correct recovery of moment magnitude and fault slip inversion at levels comparable to post-processing.</p> <div class="credits"> <p class="dwt_author">Li, Xingxing; Ge, Maorong; Zhang, Xiaohong; Zhang, Yong; Guo, Bofeng; Wang, Rongjiang; Klotz, Jürgen; Wickert, Jens</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">49</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1986SPIE..628..422D"> <span id="translatedtitle">A high <span class="hlt">precision</span> telescope <span class="hlt">pointing</span> system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A novel method of telescope <span class="hlt">pointing</span> has been developed based on He-Ne laser interferometric measurements of mirror <span class="hlt">position</span>. This technique has been applied to a Pfund-type telescope, which consists of a fixed parabolic mirror illuminated by a flat mirror which rotates in altitude and azimuth. If the parabolic mirror is stationary, the angle of <span class="hlt">pointing</span> depends only on the change of orientation of the flat mirror with respect to the parabolic mirror. The relative angles of mirrors with radius of 1 meter are measured to a <span class="hlt">precision</span> of about 0.05 arcsec. Fluctuations in the index of refraction of the atmosphere between the mirrors are the primary source of this limit; however, changes in <span class="hlt">pointing</span> <span class="hlt">position</span> involving only a gradient in the index of refraction perpendicular to the optic axis are largely compensated by this <span class="hlt">pointing</span> technique. Conversion of interference fringe counts to <span class="hlt">precise</span> angle of <span class="hlt">pointing</span> involves solutions of equations of modest complexity, but is easily handled by a small computer.</p> <div class="credits"> <p class="dwt_author">Danchi, W. C.; Arthur, A.; Fulton, R.; Peck, M.; Sadoulet, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">50</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012GeoRL..3912302W"> <span id="translatedtitle">Real-time, reliable magnitudes for large earthquakes from 1 Hz GPS <span class="hlt">precise</span> <span class="hlt">point</span> <span class="hlt">positioning</span>: The 2011 Tohoku-Oki (Japan) earthquake</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The early warning issued after the onset of the Mw 9.0 Tohoku-Oki earthquake significantly underestimated its magnitude, saturating, 120 seconds after the earthquake began, at Mw 8.1. Here we investigate whether real-time deformation data from Japan's dense network of continuously-recording Global <span class="hlt">Positioning</span> System (GPS) stations could have been used to provide a more reliable rapid estimate of the earthquake's magnitude, and ultimately a more robust tsunami forecast. We use <span class="hlt">precise</span> <span class="hlt">point</span> <span class="hlt">positioning</span> in real-time mode with broadcast clock and orbital corrections to give station <span class="hlt">positions</span> every 1 s. We then carry out a simple static inversion on a subset of stations to determine the portion of the fault that slipped and the earthquake magnitude. Unlike most previous methods, our method produces estimates of seismic moment before the earthquake rupture has completed. We find that the deformation data allow a robust magnitude estimate just ˜100 s after the earthquake onset. We also investigated the density of stations required for a robust moment magnitude estimate. Fewer than 1 station every 100 km are needed. We recommend that GPS data be incorporated into earthquake early warning systems for regions at threat from large magnitude earthquakes and tsunamis.</p> <div class="credits"> <p class="dwt_author">Wright, Tim J.; Houlié, Nicolas; Hildyard, Mark; Iwabuchi, Tetsuya</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">51</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22048044"> <span id="translatedtitle"><span class="hlt">PRECISION</span> <span class="hlt">POINTING</span> OF IBEX-Lo OBSERVATIONS</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Post-launch boresight of the IBEX-Lo instrument on board the Interstellar Boundary Explorer (IBEX) is determined based on IBEX-Lo Star Sensor observations. Accurate information on the boresight of the neutral gas camera is essential for <span class="hlt">precise</span> determination of interstellar gas flow parameters. Utilizing spin-phase information from the spacecraft attitude control system (ACS), <span class="hlt">positions</span> of stars observed by the Star Sensor during two years of IBEX measurements were analyzed and compared with <span class="hlt">positions</span> obtained from a star catalog. No statistically significant differences were observed beyond those expected from the pre-launch uncertainty in the Star Sensor mounting. Based on the star observations and their <span class="hlt">positions</span> in the spacecraft reference system, <span class="hlt">pointing</span> of the IBEX satellite spin axis was determined and compared with the <span class="hlt">pointing</span> obtained from the ACS. Again, no statistically significant deviations were observed. We conclude that no systematic correction for boresight geometry is needed in the analysis of IBEX-Lo observations to determine neutral interstellar gas flow properties. A stack-up of uncertainties in attitude knowledge shows that the instantaneous IBEX-Lo <span class="hlt">pointing</span> is determined to within {approx}0.{sup 0}1 in both spin angle and elevation using either the Star Sensor or the ACS. Further, the Star Sensor can be used to independently determine the spacecraft spin axis. Thus, Star Sensor data can be used reliably to correct the spin phase when the Star Tracker (used by the ACS) is disabled by bright objects in its field of view. The Star Sensor can also determine the spin axis during most orbits and thus provides redundancy for the Star Tracker.</p> <div class="credits"> <p class="dwt_author">Hlond, M.; Bzowski, M. [Space Research Centre of the Polish Academy of Sciences, 18A Bartycka, 00-716 Warsaw (Poland); Moebius, E.; Kucharek, H.; Heirtzler, D.; Schwadron, N. A.; Neill, M. E. O'; Clark, G. [Space Science Center and Department of Physics, University of New Hampshire, Morse Hall, 8 College Road, Durham, NH 03824 (United States); Crew, G. B. [Haystack Observatory, Massachusetts Institute of Technology, Route 40, Westford, MA 01886 (United States); Fuselier, S. [Lockheed Martin, Space Physics Lab, 3251 Hanover Street, Palo Alto, CA 94304 (United States); McComas, D. J., E-mail: mhlond@cbk.waw.pl, E-mail: eberhard.moebius@unh.edu, E-mail: gbc@haystack.mit.edu, E-mail: stephen.a.fuselier@linco.com, E-mail: DMcComas@swri.edu, E-mail: DMcComas@swri.edu [Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">52</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/363997"> <span id="translatedtitle">Algorithms for arbitrary <span class="hlt">precision</span> floating <span class="hlt">point</span> arithmetic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The author presents techniques for performing computations of very high accuracy using only straightforward floating-<span class="hlt">point</span> arithmetic operations of limited <span class="hlt">precision</span>. The validity of these techniques is proved under very general hypotheses satisfied by most implementations of floating-<span class="hlt">point</span> arithmetic. To illustrate the applications of these techniques, an algorithm is presented which computes the intersection of a line and a line segment.</p> <div class="credits"> <p class="dwt_author">Douglas M. Priest</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">53</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/20682246"> <span id="translatedtitle">Shaping a morphogen gradient for <span class="hlt">positional</span> <span class="hlt">precision</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Morphogen gradients, which provide <span class="hlt">positional</span> information to cells in a developing tissue, could in principle adopt any nonuniform profile. To our knowledge, how the profile of a morphogen gradient affects <span class="hlt">positional</span> <span class="hlt">precision</span> has not been well studied experimentally. Here, we compare the <span class="hlt">positional</span> <span class="hlt">precision</span> provided by the Drosophila morphogenetic protein Bicoid (Bcd) in wild-type (wt) embryos with embryos lacking an interacting cofactor. The Bcd gradient in the latter case exhibits decreased <span class="hlt">positional</span> <span class="hlt">precision</span> around mid-embryo compared with its wt counterpart. The domain boundary of Hunchback (Hb), a target activated by Bcd, becomes more variable in mutant embryos. By considering embryo-to-embryo, internal, and measurement fluctuations, we dissect mathematically the relevant sources of fluctuations that contribute to the error in <span class="hlt">positional</span> information. Using this approach, we show that the defect in Hb boundary <span class="hlt">positioning</span> in mutant embryos is directly reflective of an altered Bcd gradient profile with increasing flatness toward mid-embryo. Furthermore, we find that noise in the Bcd input signal is dominated by internal fluctuations but, due to time and spatial averaging, the spatial <span class="hlt">precision</span> of the Hb boundary is primarily affected by embryo-to-embryo variations. Our results demonstrate that the <span class="hlt">positional</span> information provided by the wt Bcd gradient profile is highly <span class="hlt">precise</span> and necessary for patterning <span class="hlt">precision</span>. PMID:20682246</p> <div class="credits"> <p class="dwt_author">He, Feng; Saunders, Timothy E; Wen, Ying; Cheung, David; Jiao, Renjie; ten Wolde, Pieter Rein; Howard, Martin; Ma, Jun</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">54</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50402596"> <span id="translatedtitle">High <span class="hlt">precision</span> <span class="hlt">positioning</span> with a sensor network</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We present an experimental high-<span class="hlt">precision</span> ultrasonic <span class="hlt">positioning</span> system based on a sensor network. The network can track an object moving along a straight line with an accuracy of 1 cm. The bulk of the <span class="hlt">position</span> calculation is distributed, with sensor nodes exchanging only the times-of-flight of the ultrasonic pulses, and state information.</p> <div class="credits"> <p class="dwt_author">Julio I. Concha; Jae-Hyuk Oh</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">55</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20060037304&hterms=piezo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dpiezo"> <span id="translatedtitle">Micro-<span class="hlt">Precision</span> Interferometer: <span class="hlt">Pointing</span> Control System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This paper describes the development of the wavefront tilt (<span class="hlt">pointing</span>) control system for the JPL Micro-<span class="hlt">Precision</span> Interferometer (MPI). This control system employs piezo-electric actuators and a digital imaging sensor with feedback compensation to reject errors in instrument <span class="hlt">pointing</span>. Stringent performance goals require large feedback, however, several characteristics of the plant tend to restrict the available bandwidth. A robust 7th-order wavefront tilt control system was successfully implemented on the MPI instrument, providing sufficient disturbance rejection performance to satisfy the established interference fringe visibility.</p> <div class="credits"> <p class="dwt_author">O'Brien, John</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">56</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/6282792"> <span id="translatedtitle"><span class="hlt">Precise</span> <span class="hlt">positioning</span> of patients for radiation therapy.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We have developed a number of immobilization schemes which permit <span class="hlt">precise</span> daily <span class="hlt">positioning</span> of patients for radiation therapy. Pretreatment and post-treatment radiographs have been taken with the patient in the treatment <span class="hlt">position</span> and analyzed to determine the amount of intratreatment movement. Studies of patients in the supine, seated and decubitus <span class="hlt">positions</span> indicate mean movements of less than 1 mm with a standard deviation of less than 1mm. Patients immobilized in the seated <span class="hlt">position</span> with a bite block and a mask have a mean movement of about 0.5 mm +/- 0.3 mm (s.d.), and patients immobilized in the supine <span class="hlt">position</span> with their necks hyperextended for submental therapy evidence a mean movement of about 1.4 mm +/- 0.9 mm (s.d.). With the exception of those used for the decubitus <span class="hlt">position</span>, the immobilization devices are simply fabricated out of thermoplastic casting materials readily available from orthopedic supply houses. A study of day-to-day reproducibility of patient <span class="hlt">position</span> using laser alignment and pretreatment radiographs for final verification of <span class="hlt">position</span> indicates that the initial laser alignment can be used to <span class="hlt">position</span> a patient within 2.2 mm +/- 1.4 mm (s.d.) of the intended <span class="hlt">position</span>. These results indicate that rigid immobilization devices can improve the <span class="hlt">precision</span> of radiotherapy, which would be advantageous with respect to both tumor and normal tissue coverage in certain situations. PMID:6282792</p> <div class="credits"> <p class="dwt_author">Verhey, L J; Goitein, M; McNulty, P; Munzenrider, J E; Suit, H D</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-02-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">57</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920000741&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle"><span class="hlt">Precise</span> Applications Of The Global <span class="hlt">Positioning</span> System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Report represents overview of Global <span class="hlt">Positioning</span> System (GPS). Emphasizes those aspects of theory, history, and status of GPS pertaining to potential utility for highly <span class="hlt">precise</span> scientific measurements. Current and anticipated applications include measurements of crustal motions in seismically active regions of Earth, measurements of rate of rotation of Earth and orientation of poles, tracking of non-GPS spacecraft in orbit around Earth, surveying, measurements of radio-signal-propagation delays, determinations of coordinates of ground stations, and transfer of <span class="hlt">precise</span> time signals worldwide.</p> <div class="credits"> <p class="dwt_author">Lichten, Stephen M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">58</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19990008610&hterms=positioning&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3D%2522positioning%2522"> <span id="translatedtitle">Inertial <span class="hlt">Pointing</span> and <span class="hlt">Positioning</span> System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">An inertial <span class="hlt">pointing</span> and control system and method for <span class="hlt">pointing</span> to a designated target with known coordinates from a platform to provide accurate <span class="hlt">position</span>, steering, and command information. The system continuously receives GPS signals and corrects Inertial Navigation System (INS) dead reckoning or drift errors. An INS is mounted directly on a <span class="hlt">pointing</span> instrument rather than in a remote location on the platform for-monitoring the terrestrial <span class="hlt">position</span> and instrument attitude. and for <span class="hlt">pointing</span> the instrument at designated celestial targets or ground based landmarks. As a result. the <span class="hlt">pointing</span> instrument and die INS move independently in inertial space from the platform since the INS is decoupled from the platform. Another important characteristic of the present system is that selected INS measurements are combined with predefined coordinate transformation equations and control logic algorithms under computer control in order to generate inertial <span class="hlt">pointing</span> commands to the <span class="hlt">pointing</span> instrument. More specifically. the computer calculates the desired instrument angles (Phi, Theta. Psi). which are then compared to the Euler angles measured by the instrument- mounted INS. and forms the <span class="hlt">pointing</span> command error angles as a result of the compared difference.</p> <div class="credits"> <p class="dwt_author">Yee, Robert (Inventor); Robbins, Fred (Inventor)</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">59</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.3740X"> <span id="translatedtitle">High-rate <span class="hlt">precise</span> <span class="hlt">point</span> <span class="hlt">positioning</span> (PPP) to measure seismic wave motions: An experimental comparison of GPS PPP with inertial measurement units</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">High-rate GPS has been widely used to construct displacement waveforms and to invert for source parameters of earthquakes. Almost all works on internal and external evaluation of high-rate GPS accuracy are based on GPS relative <span class="hlt">positioning</span>. We build an experimental platform to externally evaluate the accuracy of 50 Hz PPP displacement waveforms. Since the shake table allows motion in any of six degrees of freedom, we install an inertial measurement unit (IMU) to measure the attitude of the platform and transform the IMU displacements into the GPS coordinate system. The experimental results have shown that high-rate PPP can produce absolute horizontal displacement waveforms at the accuracy of 2 to 4 millimeters and absolute vertical displacement waveforms at the sub-centimeter level of accuracy within a short period of time. The significance of the experiments indicates that high-rate PPP is capable of detecting absolute seismic displacement waveforms at the same high accuracy as GPS relative <span class="hlt">positioning</span> techniques but requires no fixed datum station. We have also found a small scaling error of IMU and a small time offset of misalignment between high-rate PPP and IMU displacement waveforms by comparing the amplitudes of and cross-correlating both the displacement waveforms. For more details on this talk, one can now get access to the on-line-first version of our Journal of Geodesy paper: J Geod, DOI 10.1007/s00190-012-0606-z</p> <div class="credits"> <p class="dwt_author">Xu, Peiliang; Shi, Chuang; Fang, Rongxin; Liu, Jingnan; Niu, Xiaoji; Zhang, Quan; Yanagidani, Takashi</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">60</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/2197209"> <span id="translatedtitle">An Accelerator for Double <span class="hlt">Precision</span> Floating <span class="hlt">Point</span> Operations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We describe DPFPA (double <span class="hlt">precision</span> floating <span class="hlt">point</span> accelerator) an FPGA based coprocessor interfaced to the CPU through the PCI bus; it is conceived to accelerate the evaluation of double <span class="hlt">precision</span> floating <span class="hlt">point</span> operations. This coprocessor is based on two double <span class="hlt">precision</span> floating <span class="hlt">point</span> units: a pipelined adder and a pipelined multiplier. The work is part of a global project aimed</p> <div class="credits"> <p class="dwt_author">Giovanni Danese; Ivo De Lotto; Francesco Leporati; M. Scaricabarozzi; Alvaro Spelgatti</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_2");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a style="font-weight: bold;">3</a> <a onClick='return showDiv("page_4");' 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id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_3");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a style="font-weight: bold;">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_5");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">61</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFM.G33B0990M"> <span id="translatedtitle">Use of GNSS data for Hydrology: Applications of the method PPP (<span class="hlt">Precise</span> <span class="hlt">Point</span> <span class="hlt">Positioning</span>) with integer ambiguities fixing for hydrological studies in the Amazon basin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Applications of GNSS data is constantly being used in hydrology. One of the key applications is the characterization of river's longitudinal profiles, an information required to develop hydrological and hydrodynamic studies and to evaluate the quality of data obtained through space altimetry techniques. Some factors illustrate the challenge of establishing quality altimetry data from a GNSS receivers to obtain rivers profiles in Amazon Basin. GNSS reference network is sparse, the distance between survey <span class="hlt">points</span> and reference stations is large, rivers have an extension of several thousands of kilometers. All these factors contribute in limiting the efficiency of classical techniques of GNSS data processing like double difference. In the present work we use the Gins-PC software developed at CNES / GRGS. We discuss the capability of the PPP kinematic with integer ambiguities fixing strategy implemented in GINS-PC in processing GPS data to calculate river's longitudinal profiles in the Amazon Basin. The profiles will be processed using data obtained from GPS receivers on boarding boats along the rivers of Amazon Basin such as Negro river, Madeira river and Amazon/Solimões river. For this purpose, field campaings were conducted between 2005 and 2010 by ANA ( Brazilian National Water Agency), CPRM (Brazilian Geologic Survey), IRD (French Institute of Research by Development), Hybam ( Hydrology of Amazon Basin), PROSUL (Research project by CNPQ/UFRJ) and FOAM (From Ocean to inland waters Altimetry Monitoring) river section project. Under the proposed framework, these profiles will be then compared with profiles obtained by water level variation data using altimetry data from tracks of the Jason-2 and ENVISAT missions. The profiles will be also used to levelling some gauge stations in Amazon Basin and gauge data will be used to obtain a temporal variation of these profiles. However some gauges are strongly affected by charge effects, mainly caused by the hydrological cycle of the Amazon basin. These effects can produce a variation of about 10 cm in amplitude of vertical coordinates also obtained by GPS. Therefore, we use GRACE data to convert the hydrologic load into crustal displacements to remove these effects.</p> <div class="credits"> <p class="dwt_author">Moreira, D. M.; Calmant, S.; Perosanz, F.; Santos, A.; Santos Da Silva, J.; Seyler, F.; Ramillien, G. L.; Monteiro, A.; Rotunno, O.; Shum, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">62</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA304417"> <span id="translatedtitle"><span class="hlt">Precise</span> Absolute Navigation: An Evaluation of PPS <span class="hlt">Position</span> Management.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This report demonstrates a method whereby the <span class="hlt">Precise</span> <span class="hlt">Positioning</span> Service (PPS) solutions recorded in the field can be reprocessed at a later time with <span class="hlt">precise</span> ephemerides. The reprocessing with <span class="hlt">precise</span> ephemerides improves the quality of the navigation s...</p> <div class="credits"> <p class="dwt_author">B. R. Hermann B. S. Risinger</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">63</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/3x71nhcuenu84lhc.pdf"> <span id="translatedtitle">The <span class="hlt">precision</span> of proprioceptive <span class="hlt">position</span> sense</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The purpose of this study was to determine the <span class="hlt">precision</span> of proprioceptive localization of the hand in humans. We derived\\u000a spatial probability distributions which describe the <span class="hlt">precision</span> of localization on the basis of three different sources of\\u000a information: proprioceptive information about the left hand, proprioceptive information about the right hand, and visual information.\\u000a In the experiment subjects were seated at</p> <div class="credits"> <p class="dwt_author">Robert J. van Beers; Anne C. Sittig</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">64</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20000038224&hterms=FCM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DFCM"> <span id="translatedtitle">Design and Analysis of <span class="hlt">Precise</span> <span class="hlt">Pointing</span> Systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The mathematical models of Glovebox Integrated Microgravity Isolation Technology (g- LIMIT) dynamics/control system, which include six degrees of freedom (DOF) equations of motion, mathematical models of <span class="hlt">position</span> sensors, accelerometers and actuators, and acceleration and <span class="hlt">position</span> controller, were developed using MATLAB and TREETOPS simulations. Optimal control parameters of G-LIMIT control system were determined through sensitivity studies and its performance were evaluated with the TREETOPS model of G-LIMIT dynamics and control system. The functional operation and performance of the Tektronix DTM920 digital thermometer were studied and the inputs to the crew procedures and training of the DTM920 were documented.</p> <div class="credits"> <p class="dwt_author">Kim, Young K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">65</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50818124"> <span id="translatedtitle"><span class="hlt">Precise</span> Registration of <span class="hlt">Point</span> Clouds for Projected Fringe Image</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">An object has to be measured to recover its 3D shape in reverse engineering applications. The object surface is sampled <span class="hlt">point</span> by <span class="hlt">point</span> using a fringe projection to obtain <span class="hlt">point</span> clouds. Inheriting and optimizing algorithm is proposed to complete <span class="hlt">precise</span> registration of <span class="hlt">point</span> clouds. A mathematical model is established to obtain the required transformation parameters. The realizing procedure of the</p> <div class="credits"> <p class="dwt_author">Meng Fanwen; Wu Lushen; Luo Liping</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">66</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1277381"> <span id="translatedtitle">A floating-<span class="hlt">point</span> technique for extending the available <span class="hlt">precision</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A technique is described for expressing multilength floating-<span class="hlt">point</span> arithmetic in terms of singlelength floating <span class="hlt">point</span> arithmetic, i.e. the arithmetic for an available (say: single or double <span class="hlt">precision</span>) floating-<span class="hlt">point</span> number system. The basic algorithms are exact addition and multiplication of two singlelength floating-<span class="hlt">point</span> numbers, delivering the result as a doublelength floating-<span class="hlt">point</span> number. A straight-forward application of the technique yields a set</p> <div class="credits"> <p class="dwt_author">T. J. Dekker</p> <p class="dwt_publisher"></p> <p class="publishDate">1971-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">67</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50631994"> <span id="translatedtitle">A <span class="hlt">Precise</span> <span class="hlt">Pointing</span> Technique for Free Space Optical Networking</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In free space optical communication networks, <span class="hlt">pointing</span>, acquisition, and tracking (PAT) techniques are needed to establish and maintain optical links among the static or mobile nodes in the network. This paper describes a <span class="hlt">precise</span> <span class="hlt">pointing</span> technique to steer the local directional laser beam of an optical transceiver to a target optical transceiver at a remote transceiver node. The <span class="hlt">pointing</span> technique</p> <div class="credits"> <p class="dwt_author">Yohan Shim; Stuart D. Milner; Christopher C. Davis</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">68</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23669658"> <span id="translatedtitle"><span class="hlt">Precision</span> absolute <span class="hlt">positional</span> measurement of laser beams.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We describe an instrument which, coupled with a suitable coordinate measuring machine, facilitates the absolute measurement within the machine frame of the propagation direction of a millimeter-scale laser beam to an accuracy of around ±4 ?m in <span class="hlt">position</span> and ±20 ?rad in angle. PMID:23669658</p> <div class="credits"> <p class="dwt_author">Fitzsimons, Ewan D; Bogenstahl, Johanna; Hough, James; Killow, Christian J; Perreur-Lloyd, Michael; Robertson, David I; Ward, Henry</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-20</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">69</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50390123"> <span id="translatedtitle">Development of pneumatic high <span class="hlt">precise</span> <span class="hlt">position</span> controllable servo valve</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We developed a pneumatic high <span class="hlt">precise</span> <span class="hlt">position</span> controllable servo valve for a pneumatic <span class="hlt">precise</span> <span class="hlt">positioning</span> system. To improve the performance of a pneumatic, improvement of the servo valve characteristic is essential because the system performance is dominated by it. This valve is not affected by friction force because an air bearing is mounted on sliding surfaces of the valve. Furthermore,</p> <div class="credits"> <p class="dwt_author">Takashi Miyajima; Kazutoshi Sakaki; Takashi Shibukawa; T. Fujita; K. Kawashima; T. Kagawa</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">70</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55919980"> <span id="translatedtitle"><span class="hlt">Precise</span> <span class="hlt">Positioning</span> of Ships for Maritime Disasters Prevention Using GPS</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Most ships use the marine DGPS (Differential Global <span class="hlt">Positioning</span> System) service to know <span class="hlt">position</span> information in the sea. In Korea, the Ministry of Land Transport and Maritime Affairs (MLTM) provides the nationwide DGPS (NDGPS) service to users trying to secure the safety of traffic of ships. The <span class="hlt">precision</span> of ship <span class="hlt">position</span> information obtained by the MLTM NDGPS system is about</p> <div class="credits"> <p class="dwt_author">J. Ha; M. Heo; S. Chun; D. Cho</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">71</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26551421"> <span id="translatedtitle"><span class="hlt">Precision</span> <span class="hlt">position</span> control using combined piezo-VCM actuators</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper presents the control performance of a high-<span class="hlt">precision</span> <span class="hlt">positioning</span> table using the hybrid actuators composed of the piezoelectric (PZT) actuators and voice-coil motors (VCMs). The combined piezo-VCM actuator features two main characteristics, i.e., a large operation range due to the long stroke of VCM, and a high <span class="hlt">precision</span> and heavy load <span class="hlt">positioning</span> ability due to the actuation of PZT</p> <div class="credits"> <p class="dwt_author">Yung-Tien Liu; Rong-Fong Fung; Chun-Chao Wang</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">72</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19860007393&hterms=sonar+distance+accuracy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsonar%2Bdistance%2Baccuracy"> <span id="translatedtitle">Analysis of a method for <span class="hlt">precisely</span> relating a seafloor <span class="hlt">point</span> to a distant <span class="hlt">point</span> on land</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A study of the environmental constraints and engineering aspects of the acoustic portion of a system for making geodetic ties between undersea reference <span class="hlt">points</span> and others on land is described. Important areas in which to make such observations initially would be from the California mainland out to oceanic <span class="hlt">points</span> seaward of the San Andreas fault, and across the Aleutian Trench. The overall approach would be to operate a GPS receiver in a relative <span class="hlt">positioning</span> (interferometric) mode to provide the long range element of the baseline determination (10 to 1,000 km) and an array of <span class="hlt">precision</span> sea floor acoustic transponders to link the locally moving sea surface GPS antenna location to a fixed sea floor <span class="hlt">point</span>. Analyses of various environmental constrants (tides, waves, currents, sound velocity variations) lead to the conclusion that, if one uses a properly designed transponder having a remotely controllable <span class="hlt">precise</span> retransmission time delay, and is careful with regard to methods for installing these on the sea floor, one should, in many ocean locations, be able to achieve sub-decimeter overall system accuracy. Achievements of cm accuracy or better will require additional understanding of time and space scales of variation of sound velocity structure in the ocean at relevant locations.</p> <div class="credits"> <p class="dwt_author">Spiess, F. N.; Lowenstein, C. D.; Mcintyre, M. O.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">73</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54273512"> <span id="translatedtitle">A biaxial fast steering mirror for <span class="hlt">precision</span> optical <span class="hlt">pointing</span> systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The fast-steering mirrors often used to mitigate base motion jitter and enhance <span class="hlt">pointing</span> <span class="hlt">precision</span> are usually nonredundant mechanical devices having a flexurally suspended mirror that is capable of biaxial steering with a frequency response as high as 2000 Hz. Attention is presently given to the implementing hardware for two such mirrors' articulators; the first of these employs flexural suspension, while</p> <div class="credits"> <p class="dwt_author">J. G. Zaremba</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">74</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1482196"> <span id="translatedtitle">Magnetic levitated high <span class="hlt">precision</span> <span class="hlt">positioning</span> system based on antagonistic mechanism</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A six degree-of-freedom magnetically levitated high <span class="hlt">precision</span> micro <span class="hlt">positioning</span> system is designed to get rid of the friction which is one of the important factors limiting the resolution and accuracy of <span class="hlt">positioning</span> devices. Since magnetic levitation systems are inherently unstable, most of the emphasis is placed on a magnetic circuit design so as to increase the system dynamic stability. For</p> <div class="credits"> <p class="dwt_author">Kee-Bong Choi; Soo-Hyun Kim; Yoon Keun Kwak</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">75</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA549055"> <span id="translatedtitle">Airborne Supplemental Navigation Equipment Using The Global <span class="hlt">Positioning</span> System (GPS) <span class="hlt">Precise</span> <span class="hlt">Positioning</span> Service (PPS).</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This Military Standard Order (MSO) prescribes the minimum performance standard that airborne supplemental area navigation equipment using Global <span class="hlt">Positioning</span> System (GPS) / <span class="hlt">Precise</span> <span class="hlt">Positioning</span> Service (PPS) must meet in order to be identified with the appl...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">76</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA549056"> <span id="translatedtitle">Airborne Supplemental Navigation Equipment Using the Global <span class="hlt">Positioning</span> System (GPS)/<span class="hlt">Precise</span> <span class="hlt">Positioning</span> Service (PPS).</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This Military Standard Order (MSO) prescribes the minimum performance standard that airborne supplemental area navigation equipment using Global <span class="hlt">Positioning</span> System (GPS) / <span class="hlt">Precise</span> <span class="hlt">Positioning</span> Service (PPS) must meet in order to be identified with the appl...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">77</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://people.musc.edu/~elg26/talks/PointEstimation.ppt"> <span id="translatedtitle"><span class="hlt">Point</span> Estimation: Odds Ratios, Hazard Ratios, Risk Differences, <span class="hlt">Precision</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This site provides a Power<span class="hlt">Point</span> presentation, created by Dr. Elizabeth Garrett-Mayer of Johns Hopkins University, of a lesson and examples of <span class="hlt">point</span> estimation, odds ratios, hazard ratios, risk differences and <span class="hlt">precision</span>. The presentations is quite thorough. The author attempts to define, provide examples of, and then show the application of almost every concept. The presentation follows a easily followed and logical order. Mathematical formulas are intertwined within the slides. If further research is necessary, the author has provided a list of references and cites them during the presentation.</p> <div class="credits"> <p class="dwt_author">Garrett-Mayer, Elizabeth</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-02-11</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">78</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19970004991&hterms=pearlman+william&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpearlman%252C%2Bwilliam"> <span id="translatedtitle">Astrophysical Adaptation of <span class="hlt">Points</span>, the <span class="hlt">Precision</span> Optical Interferometer in Space</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary"><span class="hlt">POINTS</span> (<span class="hlt">Precision</span> Optical INTerferometer in Space) would perform microarcsecond optical astrometric measurements from space, yielding submicroarcsecond astrometric results from the mission. It comprises a pair of independent Michelson stellar interferometers and a laser metrology system that measures both the critical starlight paths and the angle between the baselines. The instrument has two baselines of 2 m, each with two subapertures of 35 cm; by articulating the angle between the baselines, it observes targets separated by 87 to 93 deg. <span class="hlt">POINTS</span> does global astrometry, i.e., it measures widely separated targets, which yields closure calibration, numerous bright reference stars, and absolute parallax. Simplicity, stability, and the mitigation of systematic error are the central design themes. The instrument has only three moving-part mechanisms, and only one of these must move with sub-milliradian <span class="hlt">precision</span>; the other two can tolerate a <span class="hlt">precision</span> of several tenths of a degree. Optical surfaces preceding the beamsplitter or its fold flat are interferometrically critical; on each side of the interferometer, there are only three such. Thus, light loss and wavefront distortion are minimized. <span class="hlt">POINTS</span> represents a minimalistic design developed ab initio for space. Since it is intended for astrometry, and therefore does not require the u-v-plane coverage of an imaging, instrument, each interferometer need have only two subapertures. The design relies on articulation of the angle between the interferometers and body <span class="hlt">pointing</span> to select targets; the observations are restricted to the 'instrument plane.' That plane, which is fixed in the <span class="hlt">pointed</span> instrument, is defined by the sensitive direction for the two interferometers. Thus, there is no need for siderostats and moving delay lines, which would have added many <span class="hlt">precision</span> mechanisms with rolling and sliding parts that would be required to function throughout the mission. Further, there is no need for a third interferometer, as is required when out-of-plane observations are made. An instrument for astrometry, unlike those for imaging, can be compact and yet scientifically productive. The <span class="hlt">POINTS</span> instrument is compact and therefore requires no deployment of <span class="hlt">precision</span> structures, has no low-frequency (i.e., under 100 Hz) vibration modes, and is relatively easy to control thermally. Because of its small size and mass, it is easily and quickly repointed between observations. Further, because of the low mass, it can be economically launched into high Earth orbit which, in conjunction with a solar shield, yields nearly unrestricted sky coverage and a stable thermal environment.</p> <div class="credits"> <p class="dwt_author">Reasenberg, Robert D.; Babcock, Robert W.; Murison, Marc A.; Noecker, M. Charles; Phillips, James D.; Schumaker, Bonny L.; Ulvestad, James S.; McKinley, William; Zielinski, Robert J.; Lillie, Charles F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">79</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/40191880"> <span id="translatedtitle">Higher order ionospheric effects in <span class="hlt">precise</span> GNSS <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">With the increasing number of <span class="hlt">precise</span> navigation and <span class="hlt">positioning</span> applications using Global Navigation Satellite Systems (GNSS)\\u000a such as the Global <span class="hlt">Positioning</span> System (GPS), higher order ionospheric effects and their correction become more and more important.\\u000a Whereas the first-order error can be completely eliminated by a linear combination of dual- frequency measurements, the second-\\u000a and third-order residual effects remain uncorrected in</p> <div class="credits"> <p class="dwt_author">M. Mainul Hoque; N. Jakowski</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">80</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50282481"> <span id="translatedtitle">A robust adaptive <span class="hlt">precision</span> <span class="hlt">position</span> control of PMSM</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A new control method for <span class="hlt">precision</span> robust <span class="hlt">position</span> control of a permanent magnet synchronous motor (PMSM) is presented. In direct drive motor systems, a load torque disturbances directly affects the motor shaft. The application of the load torque observer using a fixed gain to solve this problem was published by J.S. Ko et al. (see IEEE Trans. Ind. Electron., vol.40,</p> <div class="credits"> <p class="dwt_author">Jongsun Ko; Sungkoo Youn; Youngil Kim</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_3");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a 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onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_6");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">81</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24455466"> <span id="translatedtitle">Design of a reversible single <span class="hlt">precision</span> floating <span class="hlt">point</span> subtractor.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">In recent years, Reversible logic has emerged as a major area of research due to its ability to reduce the power dissipation which is the main requirement in the low power digital circuit design. It has wide applications like low power CMOS design, Nano-technology, Digital signal processing, Communication, DNA computing and Optical computing. Floating-<span class="hlt">point</span> operations are needed very frequently in nearly all computing disciplines, and studies have shown floating-<span class="hlt">point</span> addition/subtraction to be the most used floating-<span class="hlt">point</span> operation. However, few designs exist on efficient reversible BCD subtractors but no work on reversible floating <span class="hlt">point</span> subtractor. In this paper, it is proposed to present an efficient reversible single <span class="hlt">precision</span> floating-<span class="hlt">point</span> subtractor. The proposed design requires reversible designs of an 8-bit and a 24-bit comparator unit, an 8-bit and a 24-bit subtractor, and a normalization unit. For normalization, a 24-bit Reversible Leading Zero Detector and a 24-bit reversible shift register is implemented to shift the mantissas. To realize a reversible 1-bit comparator, in this paper, two new 3x3 reversible gates are proposed The proposed reversible 1-bit comparator is better and optimized in terms of the number of reversible gates used, the number of transistor count and the number of garbage outputs. The proposed work is analysed in terms of number of reversible gates, garbage outputs, constant inputs and quantum costs. Using these modules, an efficient design of a reversible single <span class="hlt">precision</span> floating <span class="hlt">point</span> subtractor is proposed. Proposed circuits have been simulated using Modelsim and synthesized using Xilinx Virtex5vlx30tff665-3. The total on-chip power consumed by the proposed 32-bit reversible floating <span class="hlt">point</span> subtractor is 0.410 W. PMID:24455466</p> <div class="credits"> <p class="dwt_author">Anantha Lakshmi, Av; Sudha, Gf</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">82</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014AAS...22412211B"> <span id="translatedtitle">High <span class="hlt">Precision</span> <span class="hlt">Pointing</span> Stability and Control for Exoplanet Missions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Exoplanet imaging and characterization space observatories require high <span class="hlt">precision</span> <span class="hlt">pointing</span> stability and stability. We have developed a toolbox of sensors, actuators and algorithms along with a systems approach to meet the demanding needs of these missions. Grown from developments and experience gained from high <span class="hlt">precision</span> Earth remote sensing missions such as the WorldView satellites, as well as high performance astrophysics missions such as Kepler and JWST, these capabilities are enabling for a wide range of future missions. The approaches take advantage of highly flexible software architectures; Enhanced ground simulation capabilities for system tuning and verification and validation; Testing capabilities to verify our modelling; High <span class="hlt">precision</span> sensors including sub-arc-second star trackers and fine guidance sensors; High bandwidth fast steering mirrors for optical path control; and high <span class="hlt">precision</span> reaction wheels and control moment gyros for overall observatory control. Many of these capabilities coupled with innovative thinking have been applied to the recent Kepler mission to enable the K2 extended mission concept.</p> <div class="credits"> <p class="dwt_author">Barnes, Arnold; Troeltzsch, John; Wiemer, Doug</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">83</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012MNRAS.419.1977P"> <span id="translatedtitle"><span class="hlt">Precise</span> CCD <span class="hlt">positions</span> of Galilean satellite-pairs</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In this paper, we present 526 <span class="hlt">precise</span> CCD <span class="hlt">positions</span> of Galilean satellite-pairs of Jupiter, which have been extracted from 441 CCD frames captured by a 1-m telescope at the Yunnan Observatory from 2002 to 2010. The four Galilean satellites (Io, Europa, Ganymede and Callisto) are used to calibrate the CCD field of view by comparing their pixel <span class="hlt">positions</span> with their theoretical <span class="hlt">positions</span> computed from two modern ephemerides of the Galilean satellites, L2 and JUP230, which have been developed by the Institut de Méchanique Céleste et de Calcul des Éphémérides and the Jet Propulsion Laboratory, respectively. In this paper, we focus on the relative <span class="hlt">position</span> of a pair of satellites with short separation (less than 85 arcsec) for good internal <span class="hlt">precision</span>. The mean (O - C) (observed minus computed) values of all these satellite-pairs in right ascension and declination are found to be no larger than 6 mas and 2 mas, respectively, for each ephemeris. The estimated <span class="hlt">precision</span> for one single observation is better than 30 mas in each direction.</p> <div class="credits"> <p class="dwt_author">Peng, Q. Y.; He, H. F.; Lainey, V.; Vienne, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">84</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50145044"> <span id="translatedtitle"><span class="hlt">Precise</span> 3-D Object <span class="hlt">Position</span> Tracking using FMCW Radar</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper presents a FMCW radar system for high <span class="hlt">precision</span> three-dimensional object <span class="hlt">position</span> tracking. Theoretical analyses of the 3-D triangulation concept and the accuracy limits are given. Three 2.45 GHz radar modules measure the distance from different spatial locations to an active reflector unit installed on the object to be localised. By modulating the radar signal in the active reflector</p> <div class="credits"> <p class="dwt_author">M. Vossiek; R. Roskosch; P. Heide</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">85</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/11797005"> <span id="translatedtitle"><span class="hlt">Precise</span> Measurement of the <span class="hlt">Positive</span> Muon Anomalous Magnetic Moment</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A <span class="hlt">precise</span> measurement of the anomalous g value, amu = \\\\(g-2\\\\)\\/2, for the <span class="hlt">positive</span> muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result amu+ = 11 659 202\\\\(14\\\\) \\\\(6\\\\)×10-10 (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard</p> <div class="credits"> <p class="dwt_author">H. N. Brown; G. Bunce; R. M. Carey; P. Cushman; G. T. Danby; P. T. Debevec; M. Deile; H. Deng; W. Deninger; S. K. Dhawan; V. P. Druzhinin; L. Duong; E. Efstathiadis; F. J. Farley; G. V. Fedotovich; S. Giron; F. Gray; D. Grigoriev; M. Grosse-Perdekamp; A. Grossmann; M. F. Hare; D. W. Hertzog; V. W. Hughes; M. Iwasaki; K. Jungmann; D. Kawall; M. Kawamura; B. I. Khazin; J. Kindem; F. Krienen; I. Kronkvist; R. Larsen; Y. Y. Lee; I. Logashenko; R. McNabb; W. Meng; J. Mi; J. P. Miller; W. M. Morse; D. Nikas; C. J. Onderwater; Y. Orlov; C. S. Özben; J. M. Paley; C. Polly; J. Pretz; R. Prigl; G. Zu Putlitz; S. I. Redin; O. Rind; B. L. Roberts; N. Ryskulov; S. Sedykh; Y. K. Semertzidis; Yu. M. Shatunov; E. P. Sichtermann; E. Solodov; M. Sossong; A. Steinmetz; L. R. Sulak; C. Timmermans; A. Trofimov; D. Urner; P. von Walter; D. Warburton; D. Winn; A. Yamamoto; D. Zimmerman</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">86</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://chemistry.ucsc.edu/~schen/NDPRW.pdf"> <span id="translatedtitle"><span class="hlt">Precise</span> <span class="hlt">Positioning</span> of Nanoparticles on Surfaces Using Scanning Probe Lithography</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Two new methods have been developed to <span class="hlt">precisely</span> <span class="hlt">position</span> gold nanoparticles on surfaces. The surface-active nanoparticles have a shell of a mixed monolayer comprised of alkanethiol and alkanedithiol molecules to anchor particles to gold surfaces via sulfur-gold chemisorption. In the first method, regions of an alkanethiol self-assembled monolayer (SAM) are shaved by the AFM tip under high force in a</p> <div class="credits"> <p class="dwt_author">Jayne C. Garno; Yiyun Yang; Nabil A. Amro; Sylvain Cruchon-Dupeyrat; Shaowei Chen; Gang-Yu Liu</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">87</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19830011846&hterms=vibration+rotating+machinery&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dvibration%2Brotating%2Bmachinery"> <span id="translatedtitle"><span class="hlt">Precision</span> optical angular <span class="hlt">position</span> marker system for rotating machinery</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">An optical system is described which generates one or more markers of the angular shaft <span class="hlt">position</span> of rotating machinery. The system consists of a light source, an optical cable, a machinery mounted lens assembly, a light detector, and a signal conditioner. Light reflected by targets on the rotor is converted to a digital output signal. The system is highly immune to extreme environments of vibration and temperature and achieved a 0.002 percent <span class="hlt">precision</span> under operational test conditions.</p> <div class="credits"> <p class="dwt_author">Barranger, J. P.</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">88</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850060311&hterms=dahlgren&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2522dahlgren%2522"> <span id="translatedtitle">A comparison of four <span class="hlt">precise</span> global <span class="hlt">positioning</span> system geodetic receivers</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Four <span class="hlt">precise</span> global <span class="hlt">positioning</span> system (GPS) geodetic receivers were operated simultaneously in January and February 1984 over ten baselines ranging in distance from 13 to 1304 km. Several of the baselines had been previously measured using very long baseline interferometry and, therefore, provide very good standards to which the satellite results can be compared. Results of these experiments are presented along with a brief description of each receiver and the associated analysis techniques.</p> <div class="credits"> <p class="dwt_author">Goad, C. C.; Sims, M. L.; Young, L. E.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">89</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19940009484&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle">Helicopter <span class="hlt">precision</span> approach capability using the Global <span class="hlt">Positioning</span> System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The period between 1 July and 31 December, 1992, was spent developing a research plan as well as a navigation system document and flight test plan to investigate helicopter <span class="hlt">precision</span> approach capability using the Global <span class="hlt">Positioning</span> System (GPS). In addition, all hardware and software required for the research was acquired, developed, installed, and verified on both the test aircraft and the ground-based reference station.</p> <div class="credits"> <p class="dwt_author">Kaufmann, David N.</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">90</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19830058720&hterms=external+environment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2522external%2Benvironment%2522"> <span id="translatedtitle">A system for load isolation and <span class="hlt">precision</span> <span class="hlt">pointing</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A system capable of satisfying the accuracy and stability requirements dictated by Shuttle-borne payloads utilizing large optics has been under joint NASA/Sperry development. This device, denoted the Annular Suspension and <span class="hlt">Pointing</span> System, employs a unique combination of conventional gimbals and magnetic bearing actuators, thereby providing for the complete isolation of the payload from its external environment, as well as for extremely accurate and stable <span class="hlt">pointing</span> (equal to about 0.01 arcsec). This effort has been pursued through the fabrication and laboratory evaluation of engineering model hardware. Results from these tests have been instrumental in generating high fidelity computer simulations of this load isolation and <span class="hlt">precision</span> <span class="hlt">pointing</span> system, and in permitting confident predictions of the system's on-orbit performance. The applicability of this system to the Solar Optical Telescope mission has been examined using the computer simulation. The worst case <span class="hlt">pointing</span> error predicted for this payload while subjected to vernier reaction control system thruster firings and crew motions aboard the Shuttle was approximately 0.006 arcsec.</p> <div class="credits"> <p class="dwt_author">Keckler, C. R.; Hamilton, B. J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">91</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19880047932&hterms=dynamic+positioning&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddynamic%2Bpositioning"> <span id="translatedtitle"><span class="hlt">Precision</span> <span class="hlt">positioning</span> of earth orbiting remote sensing systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Decimeter tracking accuracy is sought for a number of <span class="hlt">precise</span> earth sensing satellites to be flown in the 1990's. This accuracy can be achieved with techniques which use the Global <span class="hlt">Positioning</span> System (GPS) in a differential mode. A <span class="hlt">precisely</span> located global network of GPS ground receivers and a receiver aboard the user satellite are needed, and all techniques simultaneously estimate the user and GPS satellite states. Three basic navigation approaches include classical dynamic, wholly nondynamic, and reduced dynamic or hybrid formulations. The first two are simply special cases of the third, which promises to deliver subdecimeter accuracy for dynamically unpredictable vehicles down to the lowest orbit altitudes. The potential of these techniques for tracking and gravity field recovery will be demonstrated on NASA's Topex satellite beginning in 1991. Applications to the Shuttle, Space Station, and dedicated remote sensing platforms are being pursued.</p> <div class="credits"> <p class="dwt_author">Melbourne, William G.; Yunck, T. P.; Wu, S. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">92</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002SPIE.4757.....G"> <span id="translatedtitle">Integrated modeling and analysis methodology for <span class="hlt">precision</span> <span class="hlt">pointing</span> applications</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Space-based optical systems that perform tasks such as laser communications, Earth imaging, and astronomical observations require <span class="hlt">precise</span> line-of-sight (LOS) <span class="hlt">pointing</span>. A general approach is described for integrated modeling and analysis of these types of systems within the MATLAB/Simulink environment. The approach can be applied during all stages of program development, from early conceptual design studies to hardware implementation phases. The main objective is to predict the dynamic <span class="hlt">pointing</span> performance subject to anticipated disturbances and noise sources. Secondary objectives include assessing the control stability, levying subsystem requirements, supporting <span class="hlt">pointing</span> error budgets, and performing trade studies. The integrated model resides in Simulink, and several MATLAB graphical user interfaces (GUI"s) allow the user to configure the model, select analysis options, run analyses, and process the results. A convenient parameter naming and storage scheme, as well as model conditioning and reduction tools and run-time enhancements, are incorporated into the framework. This enables the proposed architecture to accommodate models of realistic complexity.</p> <div class="credits"> <p class="dwt_author">Gutierrez, Homero L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">93</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010SPIE.7733E..33P"> <span id="translatedtitle">High-<span class="hlt">precision</span> <span class="hlt">pointing</span> with the Sardinia Radio Telescope</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present here the systems aimed to measure and minimize the <span class="hlt">pointing</span> errors for the Sardinia Radio Telescope: they consist of an optical telescope to measure errors due to the mechanical structure deformations and a lasers system for the errors due to the subreflector displacement. We show here the results of the tests that we have done on the Medicina 32 meters VLBI radio telescope. The measurements demonstrate we can measure the <span class="hlt">pointing</span> errors of the mechanical structure, with an accuracy of about ~1 arcsec. Moreover, we show the technique to measure the displacement of the subreflector, placed in the SRT at 22 meters from the main mirror, within +/-0.1 mm from its optimal <span class="hlt">position</span>. These measurements show that we can obtain the needed accuracy to correct also the non repeatable <span class="hlt">pointing</span> errors, which arise on time scale varying from seconds to minutes.</p> <div class="credits"> <p class="dwt_author">Poppi, Sergio; Pernechele, Claudio; Pisanu, Tonino; Morsiani, Marco</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">94</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://dx.doi.org/10.1007/s00267-004-0270-z"> <span id="translatedtitle">Mapping stream habitats with a global <span class="hlt">positioning</span> system: Accuracy, <span class="hlt">precision</span>, and comparison with traditional methods</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">We tested the <span class="hlt">precision</span> and accuracy of the Trimble GeoXT??? global <span class="hlt">positioning</span> system (GPS) handheld receiver on <span class="hlt">point</span> and area features and compared estimates of stream habitat dimensions (e.g., lengths and areas of riffles and pools) that were made in three different Oklahoma streams using the GPS receiver and a tape measure. The <span class="hlt">precision</span> of differentially corrected GPS (DGPS) <span class="hlt">points</span> was not affected by the number of GPS <span class="hlt">position</span> fixes (i.e., geographic location estimates) averaged per DGPS <span class="hlt">point</span>. Horizontal error of <span class="hlt">points</span> ranged from 0.03 to 2.77 m and did not differ with the number of <span class="hlt">position</span> fixes per <span class="hlt">point</span>. The error of area measurements ranged from 0.1% to 110.1% but decreased as the area increased. Again, error was independent of the number of <span class="hlt">position</span> fixes averaged per polygon corner. The estimates of habitat lengths, widths, and areas did not differ when measured using two methods of data collection (GPS and a tape measure), nor did the differences among methods change at three stream sites with contrasting morphologies. Measuring features with a GPS receiver was up to 3.3 times faster on average than using a tape measure, although signal interference from high streambanks or overhanging vegetation occasionally limited satellite signal availability and prolonged measurements with a GPS receiver. There were also no differences in <span class="hlt">precision</span> of habitat dimensions when mapped using a continuous versus a <span class="hlt">position</span> fix average GPS data collection method. Despite there being some disadvantages to using the GPS in stream habitat studies, measuring stream habitats with a GPS resulted in spatially referenced data that allowed the assessment of relative habitat <span class="hlt">position</span> and changes in habitats over time, and was often faster than using a tape measure. For most spatial scales of interest, the <span class="hlt">precision</span> and accuracy of DGPS data are adequate and have logistical advantages when compared to traditional methods of measurement. ?? 2006 Springer Science+Business Media, Inc.</p> <div class="credits"> <p class="dwt_author">Dauwalter, D. C.; Fisher, W. L.; Belt, K. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">95</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008SPIE.6624E..18G"> <span id="translatedtitle">Closed loop high <span class="hlt">precision</span> <span class="hlt">position</span> control system with optical scale</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">With the developments of science of art, there are more and more demands on the high resolution control of <span class="hlt">position</span> of object to be controlled, such as lathe, product line, elements in the optical resonant cavity, telescope, and so on. As one device with high resolution, the optical scale has more and more utility within the industrial and civil applications. With one optical scale and small DC servo motor, one closed loop high resolution <span class="hlt">position</span> control system is constructed. This apparatus is used to control the <span class="hlt">position</span> of the elements of optical system. The optical scale is attached on the object or reference guide way. The object <span class="hlt">position</span> is sampled by a readhead of non-contact optical encoder. Control system processes the <span class="hlt">position</span> information and control the <span class="hlt">position</span> of object through the motion control of servo DC motor. The DC motor is controlled by one controller which is connected to an industrial computer. And the micro frictionless slide table does support the smooth motion of object to be controlled. The control algorithm of system is PID (Proportional-Integral-Differential) methods. The PID control methods have well ROBUST. The needed data to control are <span class="hlt">position</span>, velocity and acceleration of the object. These three parameters correspond to the PID characters respectively. After the accomplishments of hardware, GUI (Graphical user interface), that is, the software of control system is also programmed. The whole system is assembled by specialized worker. Through calibration experiments, the coefficients of PID are obtained respectively. And then the <span class="hlt">precision</span> of <span class="hlt">position</span> control of the system is about 0.1?m.</p> <div class="credits"> <p class="dwt_author">Ge, Cheng-liang; Liao, Yuan; He, Zhong-wu; Luo, Zhong-xiang; Huang, Zhi-wei; Wan, Min; Hu, Xiao-yang; Fan, Guo-bin; Liang, Zheng</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">96</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1850380"> <span id="translatedtitle">Electrostatic Microactuators for <span class="hlt">Precise</span> <span class="hlt">Positioning</span> of Neural Microelectrodes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Microelectrode arrays used for monitoring single and multineuronal action potentials often fail to record from the same population of neurons over a period of time likely due to micromotion of neurons away from the microelectrode, gliosis around the recording site and also brain movement due to behavior. We report here novel electrostatic microactuated microelectrodes that will enable <span class="hlt">precise</span> repositioning of the microelectrodes within the brain tissue. Electrostatic comb-drive microactuators and associated microelectrodes are fabricated using the SUMMiT V™ (Sandia's Ultraplanar Multilevel MEMS Technology) process, a five-layer polysilicon micromachining technology of the Sandia National labs, NM. The microfabricated microactuators enable <span class="hlt">precise</span> bidirectional <span class="hlt">positioning</span> of the microelectrodes in the brain with accuracy in the order of 1 ?m. The microactuators allow for a linear translation of the microelectrodes of up to 5 mm in either direction making it suitable for <span class="hlt">positioning</span> microelectrodes in deep structures of a rodent brain. The overall translation was reduced to approximately 2 mm after insulation of the microelectrodes with epoxy for monitoring multiunit activity. The microactuators are capable of driving the microelectrodes in the brain tissue with forces in the order of several micro-Newtons. Single unit recordings were obtained from the somatosensory cortex of adult rats in acute experiments demonstrating the feasibility of this technology. Further optimization of the insulation, packaging and interconnect issues will be necessary before this technology can be validated in long-term experiments.</p> <div class="credits"> <p class="dwt_author">Muthuswamy, Jit; Okandan, Murat; Jain, Tilak; Gilletti, Aaron</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">97</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AN....333.1092S"> <span id="translatedtitle">High <span class="hlt">precision</span> <span class="hlt">pointing</span> with a multiline spectrometer at the VTT</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We are investigating the <span class="hlt">pointing</span> quality of the VTT, Tenerife under the aspect of suitability for long-term heliosesimological observations. Tests have shown that thermal and mechanical loads within the telescope may create spurious image drifts with shift rates of up to 5 arcsec per hour. During daylong recordings this will reduce significantly the effective size of the field-of-view and may infer artificial lateral movements into the data. The underlying problem that not all image <span class="hlt">position</span> offsets developing during a measurement may be compensated for is common to most high-resolution solar telescopes independently of the type of <span class="hlt">pointing</span> system used. We are developing new approaches to address this problem which are to be tested in the near future at the VTT. The simulations established so far show that the problem may be reduced by more than 90 %.</p> <div class="credits"> <p class="dwt_author">Staiger, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">98</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19930054242&hterms=chong&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dchong"> <span id="translatedtitle">An optimal GPS data processing technique for <span class="hlt">precise</span> <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A mathematical formula to optimally combine dual-frequency GPS pseudorange and carrier phase (integrated Doppler) data streams into a single data stream is derived in closed form. The data combination reduces the data volume and computing time in the filtering process for parameter estimation by a factor of 4 while preserving the full data strength for <span class="hlt">precise</span> <span class="hlt">positioning</span>. The resulting single data stream is that of carrier phase measurements with both data noise and bias uncertainty strictly defined. With this mathematical formula the single stream of optimally combined GPS measurements can be efficiently formed by simple numerical calculations. Carrier phase ambiguity resolution, when feasible, is strengthened due to the preserved full data strength with the optimally combined data and the resulting longer wavelength for the ambiguity to be resolved.</p> <div class="credits"> <p class="dwt_author">Wu, Sien-Chong; Melbourne, William G.</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">99</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002PCE....27..391K"> <span id="translatedtitle">Influence of the northern ionosphere on <span class="hlt">positioning</span> <span class="hlt">precision</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The results of the analyses of the influence of the northern ionosphere on <span class="hlt">positioning</span> <span class="hlt">precision</span> are presented. The analyses rely on studying the repeatability of vectors' coordinates. These vectors were investigated during the ionospheric storms. The GPS permanent observations from the three periods of the ionospheric storms of 1999 were used: 11-16 September, 27-30 September and 10-15 October. The permanent observations from the following IGS/EUREF stations were analyzed: Onsala, Hoefn, Thule, Kiruna, Ny-Alesund, Reykjavik, Tromso and Metsahovi. Their latitude range varies from 57°N to 80°N. Software Bernese ver.4.2 was used for the analysis of the GPS observational data considering 8, 12 and 24 h sessions.</p> <div class="credits"> <p class="dwt_author">Krankowski, A.; Baran, L. W.; Shagimuratov, I. I.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">100</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70110624"> <span id="translatedtitle">An approach for filtering hyperbolically <span class="hlt">positioned</span> underwater acoustic telemetry data with <span class="hlt">position</span> <span class="hlt">precision</span> estimates</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">The use of <span class="hlt">position</span> <span class="hlt">precision</span> estimates that reflect the confidence in the <span class="hlt">positioning</span> process should be considered prior to the use of biological filters that rely on a priori expectations of the subject’s movement capacities and tendencies. <span class="hlt">Position</span> confidence goals should be determined based upon the needs of the research questions and analysis requirements versus arbitrary selection, in which filters of previous studies are adopted. Data filtering with this approach ensures that data quality is sufficient for the selected analyses and presents the opportunity to adjust or identify a different analysis in the event that the requisite <span class="hlt">precision</span> was not attained. Ignoring these steps puts a practitioner at risk of reporting errant findings.</p> <div class="credits"> <p class="dwt_author">Meckley, Trevor D.; Holbrook, Christopher M.; Wagner, C. Michael; Binder, Thomas R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_4");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return 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onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_7");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">101</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51892626"> <span id="translatedtitle"><span class="hlt">Precision</span> attitude and <span class="hlt">position</span> determination for the Advanced Land Observing Satellite (ALOS)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Advanced Land Observing Satellite (ALOS) is required to achieve stringent attitude determination accuracy (3.0×10-4deg on-board and 1.4×10-4deg ground-based), <span class="hlt">position</span> determination accuracy (1m ground-based), and attitude stability (3.9 × 10-4deg\\/5sec) in order to provide <span class="hlt">precise</span> geometric accuracy for high-resolution images without ground control <span class="hlt">points</span>. It is designed to yield the geolocation determination accuracy of 6m from attitude and <span class="hlt">position</span> estimates</p> <div class="credits"> <p class="dwt_author">Takanori Iwata</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">102</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50990037"> <span id="translatedtitle">UWB, Multi-sensors and Wifi-Mesh based <span class="hlt">precision</span> <span class="hlt">positioning</span> for urban rail traffic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Precision</span> <span class="hlt">positioning</span> for moving targets is the key issue in urban rail traffic safety assurance and operational energy saving. <span class="hlt">Precision</span> vehicle <span class="hlt">positioning</span> can improve transportation capacity. Meanwhile, personnel tracking can enhance daily operations as well as rescue capabilities in the event an accident or emergency. This paper discusses the development of <span class="hlt">precision</span> <span class="hlt">positioning</span> solution based on UWB, Multi-sensors and Wi-Fi</p> <div class="credits"> <p class="dwt_author">Lin Hui; Ye Lei; Wang Yuanfei</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">103</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005PhDT........38R"> <span id="translatedtitle">Model, control and performance of a six degree-of-freedom <span class="hlt">precision</span> <span class="hlt">pointing</span> and tracking system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In this dissertation, a six degree-of-freedom (6-DOF) <span class="hlt">precision</span> <span class="hlt">pointing</span> and tracking system is integrated to demonstrate its laser <span class="hlt">pointing</span> and tracking capability in ambient laboratory environment. Such a demonstration is intended for potential high accuracy <span class="hlt">pointing</span> and smooth angular slewing applications in space, such as free-space laser communications among satellites. The key technology adopted is the slotless permanent magnet (PM) self-bearing motor (SBM), which is first utilized to fully provide radial bearing and motoring functionality simultaneously in a novel 6-DOF magnetic actuator. The <span class="hlt">precision</span> actuator incorporates two SBMs and one active magnetic bearing (AMB), and thus allows for a complete electromagnetic suspension and <span class="hlt">precision</span> non-contact <span class="hlt">pointing</span>. The sensing scheme is critical to the feedback control of the open loop unstable magnetic actuator. Among various sensors used, the unique linear tape encoding strategy uses the same concept as in the SBM and provides high resolution and non-contact measurement for radial and angular displacements simultaneously. To accurately characterize current and negative stiffness gains in the linearized force-current-displacement relation of the large-scale SBM, the analytical force and torque expressions are derived using the Maxwell stress tensor method. A general two-dimensional (2-D) magnetic field analysis in the large effective air gap is conducted and the field components due to thick windings and PMs are formulated in explicit forms. All analytical solutions are validated by the electromagnetic finite element analyses (FEA). An analytical representation of the overall dynamic system is presented for linear controller design. Six decoupled proportional-integral-derivative (PID) controllers are designed and a real-time digital feedback control system is implemented. Intensive experiments are carried out to evaluate the closed loop performance. The actuator is capable of smooth angular slewing while maintaining good stabilization. Enhanced by a switching algorithm for smooth switches between encoder and <span class="hlt">position</span> sensing device (PSD) feedback loops, the overall system demonstrates successful acquisition and reacquisition as well as <span class="hlt">precision</span> <span class="hlt">pointing</span> and tracking capability of the laser beam. This 6-DOF <span class="hlt">precision</span> <span class="hlt">pointing</span> and tracking system achieves a <span class="hlt">pointing</span> and tracking accuracy below 1 murad with an angular resolution of 754 nrad over a large azimuth range of +/-45° using a single actuator.</p> <div class="credits"> <p class="dwt_author">Ren, Zhaohui</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">104</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890000826&hterms=schumacher&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dschumacher"> <span id="translatedtitle">Antenna <span class="hlt">pointing</span> compensation based on <span class="hlt">precision</span> optical measurement techniques</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The <span class="hlt">pointing</span> control loops of the Deep Space Network 70 meter antennas extend only to the Intermediate Reference Structure (IRS). Thus, distortion of the structure forward of the IRS due to unpredictable environmental loads can result in uncompensated boresight shifts which degrade blind <span class="hlt">pointing</span> accuracy. A system is described which can provide real time bias commands to the <span class="hlt">pointing</span> control system to compensate for environmental effects on blind <span class="hlt">pointing</span> performance. The bias commands are computed in real time based on optical ranging measurements of the structure from the IRS to a number of selected <span class="hlt">points</span> on the primary and secondary reflectors.</p> <div class="credits"> <p class="dwt_author">Schumacher, L. L.; Vivian, H. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">105</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3561985"> <span id="translatedtitle"><span class="hlt">PreCisIon</span>: PREdiction of CIS-regulatory elements improved by gene's <span class="hlt">positION</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Conventional approaches to predict transcriptional regulatory interactions usually rely on the definition of a shared motif sequence on the target genes of a transcription factor (TF). These efforts have been frustrated by the limited availability and accuracy of TF binding site motifs, usually represented as <span class="hlt">position</span>-specific scoring matrices, which may match large numbers of sites and produce an unreliable list of target genes. To improve the prediction of binding sites, we propose to additionally use the unrelated knowledge of the genome layout. Indeed, it has been shown that co-regulated genes tend to be either neighbors or periodically spaced along the whole chromosome. This study demonstrates that respective gene <span class="hlt">positioning</span> carries significant information. This novel type of information is combined with traditional sequence information by a machine learning algorithm called <span class="hlt">PreCisIon</span>. To optimize this combination, <span class="hlt">PreCisIon</span> builds a strong gene target classifier by adaptively combining weak classifiers based on either local binding sequence or global gene <span class="hlt">position</span>. This strategy generically paves the way to the optimized incorporation of any future advances in gene target prediction based on local sequence, genome layout or on novel criteria. With the current state of the art, <span class="hlt">PreCisIon</span> consistently improves methods based on sequence information only. This is shown by implementing a cross-validation analysis of the 20 major TFs from two phylogenetically remote model organisms. For Bacillus subtilis and Escherichia coli, respectively, <span class="hlt">PreCisIon</span> achieves on average an area under the receiver operating characteristic curve of 70 and 60%, a sensitivity of 80 and 70% and a specificity of 60 and 56%. The newly predicted gene targets are demonstrated to be functionally consistent with previously known targets, as assessed by analysis of Gene Ontology enrichment or of the relevant literature and databases.</p> <div class="credits"> <p class="dwt_author">Elati, Mohamed; Nicolle, Remy; Junier, Ivan; Fernandez, David; Fekih, Rim; Font, Julio; Kepes, Francois</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">106</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/752899"> <span id="translatedtitle">Robot <span class="hlt">positioning</span> based on <span class="hlt">point-to-point</span> motion capability</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This paper presents an optimal search method for determining the base location of a robot manipulator so that the robot can have a designated <span class="hlt">point-to-point</span> (PTP) motion capabilities. Based on the topological characterization of the manipulator workspace and the definitions of various p-connectivity, a computational method is developed for enumerating various PTP motion capabilities into quantitative cost functions. Then an unconstrained search by minimizing the cost function yields the task feasible location of the robot base. This methodology is useful for placement of mobile manipulators and robotic workcell layout design.</p> <div class="credits"> <p class="dwt_author">Park, Y. S.; Cho, H. S.; Koh, K. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-03-20</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">107</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/58797279"> <span id="translatedtitle">Dynamic <span class="hlt">Positioning</span> in Single-<span class="hlt">Point</span> Moorings</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper deals with the concept of and a system for complete control of the slowly varying bow motion of a bow-moored ship using dynamic <span class="hlt">positioning</span>. System performance is shown by simulated case studies with an offshore loading tanker. Significant improvements of motion behaviour and mooring force performance are demonstrated. A complete <span class="hlt">positioning</span> system is presently running successfully onboard a</p> <div class="credits"> <p class="dwt_author">Hans Srheim; Steinar Gregersen; N. A. Jenssen</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">108</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://search.asee.org/search/fetch?url=file%3A%2F%2Flocalhost%2FE%3A%2Fsearch%2Fconference%2F14%2FAC%25202007Full2861.pdf&index=conference_papers&space=129746797203605791716676178&type=application%2Fpdf&charset="> <span id="translatedtitle"><span class="hlt">Precision</span> <span class="hlt">Positioning</span> and Vibration Measurement Using Intelligent Instrumentation and Simulation Tools</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The objective of this research is to detail the development of a simple and unique instrumentation for <span class="hlt">precise</span> micro-measurement as well as vibration measurement in an integrated manufacturing set up that can be demonstrated in a student laboratory. Based on this we propose new research for a smaller embedded measurement unit. All machines have some amount of forced vibration. However, in some cases, this vibration may cause damage to the machinery. Understanding vibration in aerospace applications is critical for any system that will be exposed to vibrating motion. Previously, strain gauges and piezoelectric accelerometers have been adequate for measuring vibration. However due to the increased requirements in performance, these methods are slowly being replaced by laser-based <span class="hlt">precision</span> instruments. One of the main reasons for this transition is the fact that the equipment in these methods must be mounted on the surface of the object being measured which can result in increasing the mass and altering the frequency, mode shape of the vibrating object. Laser technology is a non-contact measuring method and provides the resolution needed to satisfy the changing requirements. In order to demonstrate <span class="hlt">precise</span> <span class="hlt">positioning</span> and motion control for creating and detecting vibrational movements, an experimental test bed was constructed. Software based simulation tools were used to control the <span class="hlt">positioning</span> system. For vibration monitoring, the vibrating surface was discretely sampled by individual laser pulses and recorded by the <span class="hlt">position</span> sensitive detector by the generation of pulses whose magnitudes are proportional to the instantaneous surface displacements. With a sufficiently high sampling rate, reconstruction of the vibration wave form is achieved by conducting peak detection of the resultant series of pulses. Vibration sensing by <span class="hlt">position</span> sensing detector and vibration sensing by interferometry were the two techniques that were experimented with the new micro-<span class="hlt">positioning</span> system. Three methods of micro-<span class="hlt">positioning</span> and measurement were experimented; a <span class="hlt">precision</span> encoder, an optical interferometer and an integrated vision system. Data was collected at successive <span class="hlt">points</span> along the translation stages. The results showed that the optical interferometer and the encoder produced the most accurate results. It was also observed that significantly higher peak optical power levels of the probe laser pulses lead to proportional enhancement in the <span class="hlt">position</span> sensitive detector response and remarkable improvement in detection sensitivity. >/br>This paper also outlines the results of the new approach in micro-<span class="hlt">positioning</span>, displacement creation and vibration sampling in high <span class="hlt">precision</span> machine tools. Additional results with the prediction of break-through detection in laser drilling manufacturing process has also been documented.</p> <div class="credits"> <p class="dwt_author">Eppes, Tom; Hill, Jonathan; Shetty, Devdas</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-10-29</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">109</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009cxo..prop.2805L"> <span id="translatedtitle"><span class="hlt">Precise</span> <span class="hlt">Positions</span> of Historically Bright X-ray Binaries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We propose to obtain brief observations of historically bright sources which are or may be X-ray binaries in order to obtain <span class="hlt">precise</span> X-ray locations. The sources are the HMXBs XTE J1543-568, 4U1901+03, and GS0834-430, the LMXB GS 0836-429, and the unclassified sources SAX J1428.6-5422, XTE J1837+037, and IGR J21117+3427. <span class="hlt">Precise</span> locations are needed for the identification of optical/IR counterparts to five of these and for the confirmation of previously proposed optical/IR identifications of two of the sources. <span class="hlt">Precise</span> locations are also used in the analysis of data from X-ray sky monitors. None of these sources is currently bright enough to be clearly detected by the RXTE ASM, but each could be sufficiently bright to be unambiguously detected in a Chandra/ACIS image.</p> <div class="credits"> <p class="dwt_author">Levine, Alan</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">110</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55397672"> <span id="translatedtitle">High-<span class="hlt">precision</span> <span class="hlt">pointing</span> with the Sardinia Radio Telescope</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We present here the systems aimed to measure and minimize the <span class="hlt">pointing</span> errors for the Sardinia Radio Telescope: they consist of an optical telescope to measure errors due to the mechanical structure deformations and a lasers system for the errors due to the subreflector displacement. We show here the results of the tests that we have done on the Medicina</p> <div class="credits"> <p class="dwt_author">Sergio Poppi; Claudio Pernechele; Tonino Pisanu; Marco Morsiani</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">111</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/772047"> <span id="translatedtitle"><span class="hlt">Pointing</span> Control System for a High <span class="hlt">Precision</span> Flight Telescope</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A <span class="hlt">pointing</span> control system is developed and tested for a flying gimbaled telescope. The two-axis <span class="hlt">pointing</span> system is capable of sub-microradian <span class="hlt">pointing</span> stability and high accuracy in the presence of large host vehicle jitter. The telescope also has high agility--it is capable of a 50-degree retarget (in both axes simultaneously) in less than 2 seconds. To achieve the design specifications, high-accuracy, high-resolution, two-speed resolvers were used, resulting in gimbal-angle measurements stable to 1.5 microradians. In addition, on-axis inertial angle displacement sensors were mounted on the telescope to provide host-vehicle jitter cancellation. The inertial angle sensors are accurate to about 100 nanoradians, but do not measure low frequency displacements below 2 Hz. The gimbal command signal includes host-vehicle attitude information, which is band-limited. This provides jitter data below 20 Hz, but includes a variable latency between 15 and 25 milliseconds. One of the most challenging aspects of this design was to combine the inertial-angle-sensor data with the less perfect information in the command signal to achieve maximum jitter reduction. The optimum blending of these two signals, along with the feedback compensation were designed using Quantitative Feedback Theory.</p> <div class="credits"> <p class="dwt_author">BENTLEY,ANTHONY E.; WILCOXEN,JEFFREY LEE</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">112</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50226310"> <span id="translatedtitle">A study on the feedback system of ultra <span class="hlt">precision</span> <span class="hlt">positioning</span> apparatus using laser interferometer</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We make a study of <span class="hlt">precision</span> apparatus that is used in various industrial machines. The study was carried out to develop a <span class="hlt">precision</span> <span class="hlt">positioning</span> apparatus, consisting of servo motor and piezoelectric actuator. This system is composed of fine and coarse apparatus, measurement system and control system. A piezoelectric actuator is designed for fine <span class="hlt">positioning</span>. Coarse <span class="hlt">positioning</span> using a lead screw</p> <div class="credits"> <p class="dwt_author">Jae-Yeol Kim; Ill-Soo Kim; Haeng-Nam Lee; Lee-Ku Kwac; Dong-Hyun Kim</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">113</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012SPIE.8458E..0HK"> <span id="translatedtitle">Power spectral density integration analysis and its application to large bandwidth, high <span class="hlt">precision</span> <span class="hlt">position</span> measurements</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">High <span class="hlt">precision</span> <span class="hlt">position</span> measurements often involve the detection of a laser beam that interacts with various components of an experimental setup. In order to achieve the highest <span class="hlt">precision</span>, instabilities that contribute to a decrease in <span class="hlt">precision</span> must be identified and quantified. Instabilities include fluctuations in the laser power, fluctuations in the laser <span class="hlt">pointing</span> and fluctuations in the phase, as well as vibrating mechanical components that are susceptible to excitations and drift. Instabilities lead to unwanted resonances and band structures in the power spectral density of the detector signals. Typically, the most important instabilities are identified by the magnitude and location of resonances or bands in the power spectral density. However, power spectral density plots can be misleading if the width or shape of a resonance or a band are not correctly accounted for. This is especially true for measurements that span a large bandwidth. Here, we discuss Power Spectral Density Integration Analysis as a more intuitive and accurate method for identifying and quantifying instabilities. Resonances and bands are readily identified as step-like features with heights that correctly represent their contribution to the error in the <span class="hlt">position</span> measurement.</p> <div class="credits"> <p class="dwt_author">Kochanczyk, Martin D.; Bartsch, Tobias F.; Taute, Katja M.; Florin, Ernst-Ludwig</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">114</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19880062984&hterms=celeste&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dceleste"> <span id="translatedtitle">A <span class="hlt">precision</span> <span class="hlt">pointing</span> system for space telescope class optical trackers</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This paper reports on the results of a study effort whose main objective was to develop a conceptual design for a space based, large-payload (3000 kg) <span class="hlt">pointing</span> system capable of both rapid slew maneuvers (0.35 rad/sec-squared) and very stable tracking (1 microrad, 1 sigma, each axis). The key features of the resulting solution are: (1) cross elevation over elevation gimbal system, (2) closed cross elevation gimbal ring, (3) graphite-epoxy structure, (4) two-motor reactionless joint torquers, (5) payload mounted vernier reaction wheel, and (6) gyrostabilized model following control system.</p> <div class="credits"> <p class="dwt_author">Sevaston, George E.; Schier, J. Alan; Iskenderian, Theodore C.; Lin, Yu-Hwan; Satter, Celeste M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">115</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890044098&hterms=servo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dservo"> <span id="translatedtitle">Control-structure interaction in <span class="hlt">precision</span> <span class="hlt">pointing</span> servo loops</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The control-structure interaction problem is addressed via stability analysis of a generic linear servo loop model. With the plant described by the rigid body mode and a single elastic mode, structural flexibility is categorized into one of three types: (1) appendage, (2) in-the-loop minimum phase, and (3) in-the-loop nonminimum phase. Closing the loop with proportional-derivative (PD) control action and introducing sensor roll-off dynamics in the feedback path, stability conditions are obtained. Trade studies are conducted with modal frequency, modal participation, modal damping, loop bandwidth, and sensor bandwidth treated as free parameters. Results indicate that appendage modes are most likely to produce instability if they are near the sensor rolloff, whereas in-the-loop modes are most dangerous near the loop bandwidth. The main goal of this paper is to provide a fundamental understanding of the control-structure interaction problem so that it may benefit the design of complex spacecraft and <span class="hlt">pointing</span> system servo loops. In this framework, the JPL Pathfinder gimbal pointer is considered as an example.</p> <div class="credits"> <p class="dwt_author">Spanos, John T.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">116</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50407559"> <span id="translatedtitle">Using low <span class="hlt">precision</span> floating <span class="hlt">point</span> numbers to reduce memory cost for MP3 decoding</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The purpose of our work has been to evaluate the practicality of using a 16-bit floating <span class="hlt">point</span> representation to store the intermediate sample values and other data in memory during the decoding of MP3 bit streams. A floating <span class="hlt">point</span> number representation offers a better trade-off between dynamic range and <span class="hlt">precision</span> than a fixed <span class="hlt">point</span> representation for a given word length.</p> <div class="credits"> <p class="dwt_author">Johan Eilert; Andreas Ehliar; Dake Liu</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">117</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.informatik.uni-trier.de/Reports/TR-08-2004/rnc6_10_hack.pdf"> <span id="translatedtitle">On Intermediate <span class="hlt">Precision</span> Required for Correctly-Rounding Decimal-to-Binary Floating-<span class="hlt">Point</span> Conversion</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The algorithms developed ten years ago in preparation for IBM's support of IEEE Floating-<span class="hlt">Point</span> on its mainframe S\\/390 processors use an overly conservative inter- mediate <span class="hlt">precision</span> to guarantee correctly-rounded results across the entire exponent range. Here we study the minimal requirement for both bounded and unbounded <span class="hlt">precision</span> on the decimal side (converting to machine <span class="hlt">precision</span> on the binary side). An</p> <div class="credits"> <p class="dwt_author">Michel Hack</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">118</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50169574"> <span id="translatedtitle">A study on adaptive load torque observer for robust <span class="hlt">precision</span> <span class="hlt">position</span> control of BLDC motor</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A new control method for <span class="hlt">precision</span> robust <span class="hlt">position</span> control of a brushless DC (BLDC) motor using asymptotically stable adaptive load torque observer is presented in the paper. <span class="hlt">Precision</span> <span class="hlt">position</span> control is obtained for the BLDC motor system approximately linearized using the field-orientation method. Many of these drive systems use BLDC motors to avoid backlash. However, the disadvantages of the motor</p> <div class="credits"> <p class="dwt_author">Jong Sun Ko; Sung Koo Youn; Bimal K. Bose</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">119</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54208984"> <span id="translatedtitle">Orbit accuracy requirement of GPS for <span class="hlt">precise</span> <span class="hlt">positioning</span> and orbit determination within local area</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Global <span class="hlt">Positioning</span> System (GPS) provides a new possibility for solving some problems relating to geodesy and geodynamics. As one powerful approach, the interferometric technique can be used for <span class="hlt">precise</span> <span class="hlt">positioning</span> without any knowledge of the <span class="hlt">precise</span> code. As a matter of fact, it is difficult to get the ephemeris with a suitable accuracy, which is necessary for data processing.</p> <div class="credits"> <p class="dwt_author">Qifeng Xu</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">120</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54865176"> <span id="translatedtitle">The <span class="hlt">precise</span> <span class="hlt">positions</span> and proper motions of 92 stars of Chinese Astronomical Almanac</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper gives the <span class="hlt">precise</span> <span class="hlt">positions</span> and proper motions of 92 stars of the Chinese Astronomical Almanac, which are not contained in FK5. Their <span class="hlt">precisions</span> are no longer satisfied. So the <span class="hlt">positions</span> and proper motions of those 92 stars were determined by using 39 catalogues in FK5 system. The accuracies of the final results are evaluated. The mean standard errors</p> <div class="credits"> <p class="dwt_author">Zhenxing Li; Haiyan Yao; Chunlin Lu</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_5");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> 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src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">121</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.jfps.jp/proceedings/tukuba2005/pdf/100132.pdf"> <span id="translatedtitle"><span class="hlt">Precise</span> <span class="hlt">Position</span> Control of Pneumatic Servo System Considered Dynamic Characteristics of Servo Valve</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Precise</span> <span class="hlt">positioning</span> system is required in the fields of semi-conductor manufacturing process. A pneumatic servo table system is one of a <span class="hlt">precise</span> <span class="hlt">positioning</span> system. The features of the table are little friction force and little heat generation. Generally, the controller of this system is designed by neglecting the characteristics of servo valves. However, in high frequency band, the response of</p> <div class="credits"> <p class="dwt_author">Takashi MIYAJIMA; Hidekuni IIDA; Toshinori FUJITA; Kenji KAWASHIMA; Toshiharu KAGAWA</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">122</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70015072"> <span id="translatedtitle">Global <span class="hlt">positioning</span> system measurements for crustal deformation: <span class="hlt">Precision</span> and accuracy</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Analysis of 27 repeated observations of Global <span class="hlt">Positioning</span> System (GPS) <span class="hlt">position</span>-difference vectors, up to 11 kilometers in length, indicates that the standard deviation of the measurements is 4 millimeters for the north component, 6 millimeters for the east component, and 10 to 20 millimeters for the vertical component. The uncertainty grows slowly with increasing vector length. At 225 kilometers, the standard deviation of the measurement is 6, 11, and 40 millimeters for the north, east, and up components, respectively. Measurements with GPS and Geodolite, an electromagnetic distance-measuring system, over distances of 10 to 40 kilometers agree within 0.2 part per million. Measurements with GPS and very long baseline interferometry of the 225-kilometer vector agree within 0.05 part per million.</p> <div class="credits"> <p class="dwt_author">Prescott, W. H.; Davis, J. L.; Svarc, J. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">123</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010SPIE.7739E..2PZ"> <span id="translatedtitle">An improved method of the spatial <span class="hlt">point</span>'s <span class="hlt">position</span> detection</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">During the experimental process of the spatial <span class="hlt">point</span>'s <span class="hlt">position</span> detection, we analyze the advantages and disadvantages of the classical method, and propose an improved method. First, we interpolate the <span class="hlt">point</span>'s data to increase the size of the image. Then use the Zernike moment to detect the edge of the <span class="hlt">point</span>. Finally, we obtain a coordinate of the center of the <span class="hlt">point</span> by using the ellipse fitting algorithm, and take this coordinate as the <span class="hlt">position</span> of the spatial <span class="hlt">point</span>. Experimental results in laboratory show that, the proposed detection method on sub-pixel level is realized to detect the spatial <span class="hlt">point</span>'s <span class="hlt">position</span> with high-accuracy. And experimental results of relative measurement with 100 meters outdoor show that, the repeatable accuracy of this method can reach 0.12 pixel during the day and 0.05 pixel at night.</p> <div class="credits"> <p class="dwt_author">Zhang, Yu; Li, Xiaofeng; Zhu, Lichun; Jin, Jing; Li, Weimin</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">124</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gmat.unsw.edu.au/snap/publications/wang_etal2001a.pdf"> <span id="translatedtitle">Stochastic Assessment of GPS Carrier Phase Measurements for <span class="hlt">Precise</span> Static Relative <span class="hlt">Positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Abstract Global <span class="hlt">Positioning</span> System (GPS) carrier phase measurements,are used in all <span class="hlt">precise</span> static relative <span class="hlt">positioning</span> applications. The GPS carrier phase measurements are generally processed using the least-squares method, for which,both functional and stochastic models,need to be carefully defined. Whilst the functional model,for <span class="hlt">precise</span> GPS <span class="hlt">positioning</span> is well documented in the literature, realistic stochastic modelling for the GPS carrier phase measurements,is</p> <div class="credits"> <p class="dwt_author">Jinling Wang; Chalermchon Satirapod; Chris Rizos</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">125</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/40191566"> <span id="translatedtitle">Stochastic assessment of GPS carrier phase measurements for <span class="hlt">precise</span> static relative <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">.  ?Global <span class="hlt">positioning</span> system (GPS) carrier phase measurements are used in all <span class="hlt">precise</span> static relative <span class="hlt">positioning</span> applications.\\u000a The GPS carrier phase measurements are generally processed using the least-squares method, for which both functional and stochastic\\u000a models need to be carefully defined. Whilst the functional model for <span class="hlt">precise</span> GPS <span class="hlt">positioning</span> is well documented in the literature,\\u000a realistic stochastic modelling for the GPS</p> <div class="credits"> <p class="dwt_author">J. Wang; C. Satirapod; C. Rizos</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">126</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/4013n8qm595fc367.pdf"> <span id="translatedtitle">Impact of temporal correlations on GPS-derived relative <span class="hlt">point</span> <span class="hlt">positions</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">.   Due to the steady progress in global <span class="hlt">positioning</span> system (GPS) technology and methods of data evaluation, it is possible to\\u000a obtain highly <span class="hlt">precise</span> relative <span class="hlt">point</span> <span class="hlt">positions</span> also for extensive geodetic networks. However, some limiting influences such\\u000a as temporal correlations of observational data are neglected in most of the GPS processing programs. Therefore, it is necessary\\u000a to consider the impact</p> <div class="credits"> <p class="dwt_author">J. Howind; H. Kutterer; B. Heck</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">127</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19950029651&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle"><span class="hlt">Precise</span> mean sea level measurements using the Global <span class="hlt">Positioning</span> System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This paper describes the results of a sea level measurement test conducted off La Jolla, California, in November of 1991. The purpose of this test was to determine accurate sea level measurements using a Global <span class="hlt">Positioning</span> System (GPS) equipped buoy. These measurements were intended to be used as the sea level component for calibration of the ERS 1 satellite altimeter. Measurements were collected on November 25 and 28 when the ERS 1 satellite overflew the calibration area. Two different types of buoys were used. A waverider design was used on November 25 and a spar design on November 28. This provided the opportunity to examine how dynamic effects of the measurement platform might affect the sea level accuracy. The two buoys were deployed at locations approximately 1.2 km apart and about 15 km west of a reference GPS receiver located on the rooftop of the Institute of Geophysics and Planetary Physics at the Scripps Institute of Oceanography. GPS solutions were computed for 45 minutes on each day and used to produce two sea level time series. An estimate of the mean sea level at both locations was computed by subtracting tide gage data collected at the Scripps Pier from the GPS-determined sea level measurements and then filtering out the high-frequency components due to waves and buoy dynamics. In both cases the GPS estimate differed from Rapp's mean altimetric surface by 0.06 m. Thus, the gradient in the GPS measurements matched the gradient in Rapp's surface. These results suggest that accurate sea level can be determined using GPS on widely differing platforms as long as care is taken to determine the height of the GPS antenna phase center above water level. Application areas include measurement of absolute sea level, of temporal variations in sea level, and of sea level gradients (dominantly the geoid). Specific applications would include ocean altimeter calibration, monitoring of sea level in remote regions, and regional experiments requiring spatial and temporal resolution higher than that available from altimeter data.</p> <div class="credits"> <p class="dwt_author">Kelecy, Thomas M.; Born, George H.; Parke, Michael E.; Rocken, Christian</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">128</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014SPIE.9158E..08X"> <span id="translatedtitle">High-<span class="hlt">precision</span> DEM reconstruction based on airborne LiDAR <span class="hlt">point</span> clouds</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Airborne LiDAR <span class="hlt">point</span> clouds have become important data sources for DEM generation recently; however the problem of low <span class="hlt">precision</span> and low efficiency in DEM production still exists. This paper proposes a new technical scheme for high-<span class="hlt">precision</span> DEM production based on airborne LiDAR <span class="hlt">point</span> clouds systematically. Firstly, an elevation and density analysis method is applied to filter out outliers. Secondly, ground <span class="hlt">points</span> are detected by an improved filter algorithm based on the hierarchical smoothing method. Finally, feature lines are extracted by the planar surface fitting and intersecting method, and a simple data structure of feature lines preserved DEM is proposed to achieve reconstructing high accuracy DEM, combing feature lines with ground <span class="hlt">points</span>. Experimental results show that the proposed scheme is able to compensate for deficiencies of existing DEM reconstruction techniques and can meet the needs of high <span class="hlt">precision</span> DEM production based on LiDAR data.</p> <div class="credits"> <p class="dwt_author">Xu, Jingzhong; Kou, Yuan; Wang, Jun</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">129</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007SPIE.6722E..15X"> <span id="translatedtitle">Research on key techniques of nanometer scale macro-micro dual-drive <span class="hlt">precision</span> <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">With the development of science and technology, high <span class="hlt">precision</span> of <span class="hlt">positioning</span> platform is needed in many areas, for example, cell fusing in biology and <span class="hlt">precision</span> surgery in medical area. In such areas, both high efficiency and high <span class="hlt">precision</span> are needed in some cases, for example, semiconductor processing equipment, super <span class="hlt">precision</span> lathe etc. In a word, <span class="hlt">precision</span> <span class="hlt">positioning</span> platform becomes an important tool in exploring microscope world. <span class="hlt">Precision</span> <span class="hlt">positioning</span> platform is a key element in microscope operation. Macro/micro dual-drive <span class="hlt">precision</span> <span class="hlt">positioning</span> is a key technique in high-efficiency high-<span class="hlt">precision</span> area. By such techniques, large distance and high <span class="hlt">precision</span> can get. In order to realize nanometer scale macro/micro dual-drive <span class="hlt">precision</span> <span class="hlt">positioning</span> there are some key problems. First, system structure of macro/micro combination <span class="hlt">precision</span> <span class="hlt">positioning</span> platform is worthy to work on. Another key work is realization method of micrometer scale macroscope motion and nanometer scale microscope motion. The third is mechanics, drive, detection and control techniques in nanometer scale <span class="hlt">positioning</span> of piezoelectric ceramics drive, in which realization of nanometer scale microscope <span class="hlt">positioning</span> and micro drive is important by solving hysteresis, creep deformation and non-linearity in piezoelectric ceramics driving. To solve hysteresis problem, instead of traditional Preisach algorithm, a new type hysteresis model with simple computation and identification is needed. The inverse model is also easily to get. So we can present new control method to solve hysteresis and creep deformation problem based on this inverse model. Another way, hysteresis and creep deformation problem exist in traditional voltage-feedback power source for piezoelectric ceramics. To solve this problem, a new type current feedback power source for piezoelectric ceramics is presented. In the end, a macro-micro dual-drive super <span class="hlt">precision</span> <span class="hlt">positioning</span> mechanism is presented. Combining macro with micro actuator, a system with large workspace and high resolution of motion is presented. The linear direct-drive motor is used in the macroscope motion and high frequency PZT-driven microscope stage is embedded in the motor and compensates the <span class="hlt">position</span> error. A high-resolution linear encoder is integrated into the closed-loop feedback, which is used to measure the <span class="hlt">position</span> of the end-effect in microscope scale.</p> <div class="credits"> <p class="dwt_author">Xie, Xiaohui; Du, Ruxu</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">130</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50041329"> <span id="translatedtitle">Evaluation of GPS <span class="hlt">precise</span> <span class="hlt">positioning</span> service autonomous integrity monitoring performance for military applications</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The majority of research regarding Global <span class="hlt">Positioning</span> System (GPS) integrity has focused on receiver autonomous integrity monitoring (RAIM) for commercial aircraft navigation, and is, consequently, restricted to measurements obtained from the standard <span class="hlt">positioning</span> service (SPS). This paper examines the integrity issue from a military applications perspective. Analysis is conducted using GPS measurements from the <span class="hlt">precise</span> <span class="hlt">positioning</span> service (PPS) which provides</p> <div class="credits"> <p class="dwt_author">Barbara J. Kozel; Michael A. Cardoza</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">131</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/728082"> <span id="translatedtitle">Adaptive <span class="hlt">Precision</span> Floating-<span class="hlt">Point</span> Arithmetic and Fast Robust Geometric Predicates</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">.    Exact computer arithmetic has a variety of uses, including the robust implementation of geometric algorithms. This article\\u000a has three purposes. The first is to offer fast software-level algorithms for exact addition and multiplication of arbitrary\\u000a <span class="hlt">precision</span> floating-<span class="hlt">point</span> values. The second is to propose a technique for adaptive <span class="hlt">precision</span> arithmetic that can often speed\\u000a these algorithms when they are</p> <div class="credits"> <p class="dwt_author">Jonathan Richard Shewchuk</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">132</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55785986"> <span id="translatedtitle">Relative <span class="hlt">positioning</span> <span class="hlt">precision</span> of the wide-angle airborne laser ranging system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The <span class="hlt">positioning</span> <span class="hlt">precision</span> of ground-based targets is studied as a function of instrument and experiment parameters of the wide-angle airborne laser ranging system (WA-ALRS). The models for range measurements, validated in previous ground-based experiments, are used for simulating aircraft measurements. It is shown that the <span class="hlt">positioning</span> <span class="hlt">precision</span>, evaluated from the a posteriori covariance matrix, can be optimized with respect to</p> <div class="credits"> <p class="dwt_author">Olivier Bock</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">133</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19730022872&hterms=hardware+ERP&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhardware%2BERP"> <span id="translatedtitle">Study of <span class="hlt">precise</span> <span class="hlt">positioning</span> at L-band using communications satellites</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The L-band <span class="hlt">positioning</span> experiment is reported which encompassed experiment design, experimentation, and data reduction and analysis. In the experiment the ATS-5 synchronous satellite L-band transponder was used in conjunction with the modified ALPHA 2 navigation receivers to demonstrate the technical capability of <span class="hlt">precision</span> <span class="hlt">position</span> fixing for oceanographic purposes. The feasibility of using relative ranging techniques implemented by two identical receiving systems, properly calibrated, to determine a line of <span class="hlt">position</span> accurately on the surface of the earth was shown. The program demonstrated the level of resolution, repeatibility, <span class="hlt">precision</span>, and accuracy of existing modest-cost effective navigation equipment. The experiment configuration and data reduction techniques were developed in parallel with the hardware modification tasks. Test results verify the ability of a satellite-based system to satisfy the requirements of <span class="hlt">precision</span> <span class="hlt">position</span> fixing.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1971-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">134</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.1741A"> <span id="translatedtitle">Employing Tropospheric Numerical Weather Prediction Model for High-<span class="hlt">Precision</span> GNSS <span class="hlt">Positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In the past few years is increasing the necessity of realizing high accuracy <span class="hlt">positioning</span>. In this sense, the spatial technologies have being widely used. The GNSS (Global Navigation Satellite System) has revolutionized the geodetic <span class="hlt">positioning</span> activities. Among the existent methods one can emphasize the <span class="hlt">Precise</span> <span class="hlt">Point</span> <span class="hlt">Positioning</span> (PPP) and network-based <span class="hlt">positioning</span>. But, to get high accuracy employing these methods, mainly in real time, is indispensable to realize the atmospheric modeling (ionosphere and troposphere) accordingly. Related to troposphere, there are the empirical models (for example Saastamoinen and Hopfield). But when highly accuracy results (error of few centimeters) are desired, maybe these models are not appropriated to the Brazilian reality. In order to minimize this limitation arises the NWP (Numerical Weather Prediction) models. In Brazil the CPTEC/INPE (Center for Weather Prediction and Climate Studies / Brazilian Institute for Spatial Researches) provides a regional NWP model, currently used to produce Zenithal Tropospheric Delay (ZTD) predictions (http://satelite.cptec.inpe.br/zenital/). The actual version, called eta15km model, has a spatial resolution of 15 km and temporal resolution of 3 hours. In this paper the main goal is to accomplish experiments and analysis concerning the use of troposphere NWP model (eta15km model) in PPP and network-based <span class="hlt">positioning</span>. Concerning PPP it was used data from dozens of stations over the Brazilian territory, including Amazon forest. The results obtained with NWP model were compared with Hopfield one. NWP model presented the best results in all experiments. Related to network-based <span class="hlt">positioning</span> it was used data from GNSS/SP Network in São Paulo State, Brazil. This network presents the best configuration in the country to realize this kind of <span class="hlt">positioning</span>. Actually the network is composed by twenty stations (http://www.fct.unesp.br/#!/pesquisa/grupos-de-estudo-e-pesquisa/gege//gnss-sp-network2789/). The results obtained employing NWP model also were compared to Hopfield one, and the results were very interesting. The theoretical concepts, experiments, results and analysis will be presented in this paper.</p> <div class="credits"> <p class="dwt_author">Alves, Daniele; Gouveia, Tayna; Abreu, Pedro; Magário, Jackes</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">135</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/16185235"> <span id="translatedtitle">A note on efficient regression estimators with <span class="hlt">positive</span> breakdown <span class="hlt">point</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In this note we prove that for certain types of regression estimators with <span class="hlt">positive</span> breakdown <span class="hlt">point</span>, the finite sample efficiencies can be arbitrarily low when the design is unfavorable. In particular, the estimator proposed by Yohai and Zamar (1988), which is asymptotically efficient when the errors are normal, falls in this category.</p> <div class="credits"> <p class="dwt_author">S. Morgenthaler</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">136</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51025973"> <span id="translatedtitle">Theoretical Research on Adjacent Multistation <span class="hlt">Point</span> Cloud Data <span class="hlt">Precision</span> Combination in 3D Laser Scanning</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Adjacent multi-station rotational scanning the target band with the 3D laser scanner ( Leica ScanStation II ) .acquires the 3D <span class="hlt">point</span> cloud models of every rotational <span class="hlt">position</span>. Adjacent multi-station <span class="hlt">point</span> seriate cloud models have been registered, acquires the correspondent <span class="hlt">points</span>. Then combines <span class="hlt">point</span> cloud models with the theory of single strip aerial triangulation, acquires coordinates of cloud models in the</p> <div class="credits"> <p class="dwt_author">Tianzi Li; Youfeng Zou</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">137</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920034312&hterms=chong&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dchong"> <span id="translatedtitle">GPS-based orbit determination and <span class="hlt">point</span> <span class="hlt">positioning</span> under selective availability</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Selective availability (SA) degrades the <span class="hlt">positioning</span> accuracy for nondifferential users of the GPS Standard <span class="hlt">Positioning</span> Service (SPS). The often quoted SPS accuracy available under normal conditions is 100 m 2DRMS. In the absence of more specific information, many prospective SPS users adopt the 100 m value in their planning, which exaggerates the error in many cases. SA error is examined for <span class="hlt">point</span> <span class="hlt">positioning</span> and dynamic orbit determination for an orbiting user. To minimize SA error, nondifferential users have several options: expand their field of view; observe as many GPS satellites as possible; smooth the error over time; and employ <span class="hlt">precise</span> GPS ephemerides computed independently, as by NASA and the NGS, rather than the broadcast ephemeris. Simulations show that 3D <span class="hlt">point</span> <span class="hlt">position</span> error can be kept to 30 m, and this can be smoothed to 3 m in a few hours.</p> <div class="credits"> <p class="dwt_author">Bar-Sever, Yoaz E.; Yunck, Thomas P.; Wu, Sien-Chong</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">138</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014OptLE..62...31L"> <span id="translatedtitle">A novel orientation and <span class="hlt">position</span> measuring system for large & medium scale <span class="hlt">precision</span> assembly</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In the field of <span class="hlt">precision</span> assembly of large & medium scale, the orientation and <span class="hlt">position</span> measurement system is quite demanding. In this paper a novel measuring system, consisting of four motorized stages, a laser rangefinder, an autocollimator and a camera is proposed to assist <span class="hlt">precision</span> assembly. Through the design of coaxial optical system, the autocollimator is integrated with a laser rangefinder into a collimation rangefinder, which is used for measuring orientation and <span class="hlt">position</span> synchronously. The laser spot is adopted to guide autocollimation over a large space and assist the camera in finding collimated measurand. The mathematical models and practical calibration methods for measurement are elaborated. The preliminary experimental results agree with the methods currently being used for orientation and <span class="hlt">position</span> measurement. The measuring method provides an alternative choice for the metrology in <span class="hlt">precision</span> assembly.</p> <div class="credits"> <p class="dwt_author">Li, Yuhe; Qiu, Yongrong; Chen, Yanxiang; Guan, Kaisen</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">139</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1996PPMtO..15...18L"> <span id="translatedtitle">The <span class="hlt">precise</span> <span class="hlt">positions</span> and proper motions of 92 stars of Chinese Astronomical Almanac.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This paper gives the <span class="hlt">precise</span> <span class="hlt">positions</span> and proper motions of 92 stars of the Chinese Astronomical Almanac, which are not contained in FK5. Their <span class="hlt">precisions</span> are no longer satisfied. So the <span class="hlt">positions</span> and proper motions of those 92 stars were determined by using 39 catalogues in FK5 system. The accuracies of the final results are evaluated. The mean standard errors of 92 stars are 0?066 and 0?067 for right ascension and declination at mean epoch, 0?215 and 0?218 per century for proper motion respectively.</p> <div class="credits"> <p class="dwt_author">Li, Zhenxing; Yao, Haiyan; Lu, Chunlin</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">140</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/1651308"> <span id="translatedtitle">Importance of <span class="hlt">precise</span> <span class="hlt">positioning</span> for proton beam therapy in the base of skull and cervical spine.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Using proton beam therapy, high doses have been delivered to chordomas and chondrosarcomas of the base of skull and cervical spine. Dose inhomogeneity to the tumors has been accepted in order to maintain normal tissue tolerances, and detailed attention to patient immobilization and to <span class="hlt">precise</span> <span class="hlt">positioning</span> has minimized the margins necessary to ensure these dose constraints. This study examined the contribution of <span class="hlt">precise</span> <span class="hlt">positioning</span> to the better dose localization achieved in these treatments. Three patients whose tumors represented different anatomic geometries were studied. Treatment plans were developed which treated as much of the tumor as possible to 74 Cobalt-Gray-Equivalent (CGE) while maintaining the central brain stem and central spinal cord at less than or equal to 48 CGE, the surface of the brain stem, surface of the spinal cord, and optic structures at less than or equal to 60 CGE, and the temporal lobes at less than or equal to 5% likelihood of complication using a biophysical model of normal tissue complication probability. Two <span class="hlt">positioning</span> accuracies were assumed: 3 mm and 10 mm. Both proton beam plans and 10 MV X ray beam plans were developed with these assumptions and dose constraints. In all cases with the same <span class="hlt">positioning</span> uncertainties, the proton beam plans delivered more dose to a larger percentage of the tumor volume and the estimated tumor control probability was higher than with the X ray plans. However, without <span class="hlt">precise</span> <span class="hlt">positioning</span> both the proton plans and the X ray plans deteriorated, with a 12% to 25% decrease in estimated tumor control probability. In all but one case, the difference between protons with good <span class="hlt">positioning</span> and poor <span class="hlt">positioning</span> was greater than the difference between protons and X rays, both with good <span class="hlt">positioning</span>. Hence in treating these tumors, which are in close proximity to critical normal tissues, attention to immobilization and <span class="hlt">precise</span> <span class="hlt">positioning</span> is essential. With good <span class="hlt">positioning</span>, proton beam therapy permits higher doses to significantly more of the tumor in these sites than do X rays. PMID:1651308</p> <div class="credits"> <p class="dwt_author">Tatsuzaki, H; Urie, M M</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-08-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_6");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return 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src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">141</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013JGeod..87..825S"> <span id="translatedtitle">Improvement of GPS/acoustic seafloor <span class="hlt">positioning</span> <span class="hlt">precision</span> through controlling the ship's track line</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">precision</span> of GPS/acoustic seafloor <span class="hlt">positioning</span> was improved by introducing a hull-mounted onboard system in March 2008, which allows us to conduct acoustic ranging measurements with the vessel sailing along the pre-determined track lines, while the early system before 2008 could only adopt the uncontrollable drifting observation. The continuity of the <span class="hlt">positioning</span> results due to the transition was first confirmed through the comparison between results from sailing and drifting observations conducted in parallel. Using the data acquired for about 3 years since 2008, the repeatability of the determined <span class="hlt">position</span> for the sailing observation was evaluated to be about 2 cm in root mean squares in the horizontal component, significantly better than that for the early drifting observation. The improvement of <span class="hlt">positioning</span> <span class="hlt">precision</span> probably resulted from the improvement of geometric distribution of acoustic ranging data by controlling the track lines. It was also shown that the sailing observation allows to obtain reliable results with a smaller amount of data. Comparison between the results in different sea regions suggests that <span class="hlt">positioning</span> <span class="hlt">precision</span> is better in the region along the Nankai Trough than in the region along the Japan Trench, probably because of the complicated acoustic velocity structure of seawater often observed in the latter. Furthermore, the <span class="hlt">precision</span> of height determination was also improved, which leads us to expect that vertical crustal movement will be detectable in the future through accumulation of data as well as further technology development.</p> <div class="credits"> <p class="dwt_author">Sato, M.; Fujita, M.; Matsumoto, Y.; Saito, H.; Ishikawa, T.; Asakura, T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">142</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/860342"> <span id="translatedtitle">High-<span class="hlt">Precision</span> Floating-<span class="hlt">Point</span> Arithmetic in ScientificComputation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">At the present time, IEEE 64-bit floating-<span class="hlt">point</span> arithmetic is sufficiently accurate for most scientific applications. However, for a rapidly growing body of important scientific computing applications, a higher level of numeric <span class="hlt">precision</span> is required: some of these applications require roughly twice this level; others require four times; while still others require hundreds or more digits to obtain numerically meaningful results. Such calculations have been facilitated by new high-<span class="hlt">precision</span> software packages that include high-level language translation modules to minimize the conversion effort. These activities have yielded a number of interesting new scientific results in fields as diverse as quantum theory, climate modeling and experimental mathematics, a few of which are described in this article. Such developments suggest that in the future, the numeric <span class="hlt">precision</span> used for a scientific computation may be as important to the program design as are the algorithms and data structures.</p> <div class="credits"> <p class="dwt_author">Bailey, David H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-12-31</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">143</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013SPIE.8580E..19J"> <span id="translatedtitle">A device to improve the SNR of the measurement of the <span class="hlt">positional</span> floating reference <span class="hlt">point</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Previous studies have preliminarily validated the floating reference method and shown that it has the potential to improve the accuracy of non-invasive blood glucose sensing by Near-Infrared Spectroscopy. In order to make this method practical, it is necessary to <span class="hlt">precisely</span> verify and measure the existence and variation features of the <span class="hlt">positional</span> floating reference <span class="hlt">point</span>. In this talk, a device which can <span class="hlt">precisely</span> verify and measure the <span class="hlt">positional</span> floating reference <span class="hlt">point</span> is built. Since the light intensity of diffuse reflectance from the tested sample is very weak, a multipath detecting fibers system was built to improve signal-to-noise ratio. In this system, the fibers encircle the light source fiber which is regarded as the reference center of detecting fibers while they are moving. In addition, the <span class="hlt">position</span> of each fiber is accurately controlled by manual translation stage to keep all detecting fibers always in the same radius around light source fiber. This ensures that received signal is coming from the same radial distance of light source. The variation of signal-to-noise ratio along with the different radial distance was investigated based on experiments. Results show that the application of this device could improve signal-to-noise ratio, and provide a new experimental method for the further study of <span class="hlt">positional</span> floating reference <span class="hlt">point</span>.</p> <div class="credits"> <p class="dwt_author">Jiang, Jingying; Rong, Xuzheng; Zhang, Hao; Xu, Kexin</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">144</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3348824"> <span id="translatedtitle">Compact Integration of a GSM-19 Magnetic Sensor with High-<span class="hlt">Precision</span> <span class="hlt">Positioning</span> using VRS GNSS Technology</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Magnetic data consists of a sequence of collected <span class="hlt">points</span> with spatial coordinates and magnetic information. The spatial location of these <span class="hlt">points</span> needs to be as exact as possible in order to develop a <span class="hlt">precise</span> interpretation of magnetic anomalies. GPS is a valuable tool for accomplishing this objective, especially if the RTK approach is used. In this paper the VRS (Virtual Reference Station) technique is introduced as a new approach for real-time <span class="hlt">positioning</span> of magnetic sensors. The main advantages of the VRS approach are, firstly, that only a single GPS receiver is needed (no base station is necessary), reducing field work and equipment costs. Secondly, VRS can operate at distances separated 50–70 km from the reference stations without degrading accuracy. A compact integration of a GSM-19 magnetometer sensor with a geodetic GPS antenna is presented; this integration does not diminish the operational flexibility of the original magnetometer and can work with the VRS approach. The coupled devices were tested in marshlands around Gandia, a city located approximately 100 km South of Valencia (Spain), thought to be the site of a Roman cemetery. The results obtained show adequate geometry and high-<span class="hlt">precision</span> <span class="hlt">positioning</span> for the structures to be studied (a comparison with the original low <span class="hlt">precision</span> GPS of the magnetometer is presented). Finally, the results of the magnetic survey are of great interest for archaeological purposes.</p> <div class="credits"> <p class="dwt_author">Martin, Angel; Padin, Jorge; Anquela, Ana Belen; Sanchez, Juan; Belda, Santiago</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">145</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/35644010"> <span id="translatedtitle">Clinical <span class="hlt">precision</span> of myofascial trigger <span class="hlt">point</span> location in the trapezius muscle</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Myofascial trigger <span class="hlt">points</span> (TrPs) have been clinically described as discrete areas of muscle tenderness presenting in taut bands of skeletal muscle. Using well-defined clinical criteria, prior investigations have demonstrated interrater reliability in the diagnosis of TrPs within a given muscle. No reports exist, however, with respect to the <span class="hlt">precision</span> with which experienced clinicians can determine the anatomic locations of TrPs</p> <div class="credits"> <p class="dwt_author">Veronica M Sciotti; Veronica L Mittak; Lisa DiMarco; Lillian M Ford; Julie Plezbert; Eileen Santipadri; Janet Wigglesworth; Kevin Ball</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">146</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012Nanot..23v5303R"> <span id="translatedtitle">Single crystal silicon nanopillars, nanoneedles and nanoblades with <span class="hlt">precise</span> <span class="hlt">positioning</span> for massively parallel nanoscale device integration</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Arrays of <span class="hlt">precisely</span> <span class="hlt">positioned</span> single crystal silicon nanopillars, nanoneedles, and nanoblades with minimum feature sizes as small as 30 nm are fabricated using entirely scalable top-down fabrication techniques. Using the same scalable technologies, devices consisting of electrically connected silicon nanopillars with multiple addressable electrodes for each nanostructure are realized. The arrays of nanopillars, nanoneedles, and nanoblades are shown to exhibit Raman signal enhancement on 1,2-benzenedithiol monolayers, opening a path to nanodevices that manipulate, <span class="hlt">position</span>, detect and analyze molecules.</p> <div class="credits"> <p class="dwt_author">Roper, Christopher S.; Gutés, Albert; Carraro, Carlo; Howe, Roger T.; Maboudian, Roya</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">147</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54737020"> <span id="translatedtitle">Etching of deep grooves for the <span class="hlt">precise</span> <span class="hlt">positioning</span> of cleaves in semiconductor lasers</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Photoelectrochemical etching of InP is used to etch deep (80 ..mu..m), narrow (20 ..mu..m) grooves. The grooves are used to <span class="hlt">precisely</span> <span class="hlt">position</span> cleaves in semiconductor lasers and to demonstrate the first wafer processing of long\\/short cleaved-coupled-cavity (C³) lasers. Large numbers of low threshold C³ lasers wth very similar cavity lengths were obtained.</p> <div class="credits"> <p class="dwt_author">J. E. Bowers; B. R. Hemenway; D. P. Wilt</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">148</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56788002"> <span id="translatedtitle">Etching of deep grooves for the <span class="hlt">precise</span> <span class="hlt">positioning</span> of cleaves in semiconductor lasers</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Photoelectrochemical etching of InP is used to etch deep (80 ?m), narrow (20 ?m) grooves. The grooves are used to <span class="hlt">precisely</span> <span class="hlt">position</span> cleaves in semiconductor lasers and to demonstrate the first wafer processing of long\\/short cleaved-coupled-cavity (C3) lasers. Large numbers of low threshold C3 lasers wth very similar cavity lengths were obtained.</p> <div class="credits"> <p class="dwt_author">J. E. Bowers; B. R. Hemenway; D. P. Wilt</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">149</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26551304"> <span id="translatedtitle"><span class="hlt">Precision</span> <span class="hlt">positioning</span> of a DC-motor-driven aerostatic slide system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper deals with <span class="hlt">precision</span> <span class="hlt">positioning</span> in the presence of friction. The object studied is an aerostatic slide system driven by a DC motor with brushes that introduce friction to the system. For such systems, models that do not account for friction can only be used to describe the macrodynamic behavior. The microdynamic behavior is significantly different. Instead of designing</p> <div class="credits"> <p class="dwt_author">Junhong Mao; Hiroyuki Tachikawa; Akira Shimokohbe</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">150</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1464643"> <span id="translatedtitle"><span class="hlt">Precise</span> tracking of remote sensing satellites with the Global <span class="hlt">Positioning</span> System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Global <span class="hlt">Positioning</span> System (GPS) can be applied in a number of ways to track remote sensing satellites at altitudes below 3000 km with accuracies of better than 10 cm. All techniques use a <span class="hlt">precise</span> global network of GPS ground receivers operating in concert with a receiver aboard the user satellite, and all estimate the user orbit, GPS orbits, and</p> <div class="credits"> <p class="dwt_author">THOMAS P. YUNCK; SIEN-CHONG WU; JIUN-TSONG WU; CATHERINE L. THORNTON</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">151</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/49229973"> <span id="translatedtitle">MRPC-PET: A new technique for high <span class="hlt">precision</span> time and <span class="hlt">position</span> measurements</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The purpose of this paper is to consider a new technology for medical diagnosis: the MRPC-PET. This technology allows excellent time resolution together with 2-D <span class="hlt">position</span> information thus providing a fundamental step in this field. The principle of this method is based on the Multigap Resistive Plate Chamber (MRPC) capable of high <span class="hlt">precision</span> time measurements. We have previously found that</p> <div class="credits"> <p class="dwt_author">K. Doroud; D. Hatzifotiadou; S. Li; M. C. S. Williams; A. Zichichi; R. Zuyeuski</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">152</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26349444"> <span id="translatedtitle">Ultra <span class="hlt">precision</span> <span class="hlt">positioning</span> system for servo motor–piezo actuator using the dual servo loop and digital filter implementation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The ultra <span class="hlt">precision</span> <span class="hlt">positioning</span> technique has become one of the important parts in the development of <span class="hlt">precision</span> machines. For <span class="hlt">positioning</span> systems having a long stroke with ultra <span class="hlt">precision</span>, a combined system including a global stage (coarse stage) and a micro stage (fine stage) is designed in this paper. A ball screw based servo motor is used as the global stage</p> <div class="credits"> <p class="dwt_author">Heui Jae Pahk; Dong Sung Lee; Jong Ho Park</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">153</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20070036657&hterms=dynamic+positioning&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ddynamic%2Bpositioning"> <span id="translatedtitle">Dilution of <span class="hlt">Precision</span>-Based Lunar Navigation Assessment for Dynamic <span class="hlt">Position</span> Fixing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The NASA Vision for Space Exploration is focused on the return of astronauts to the Moon. While navigation systems have already been proven in the Apollo missions to the moon, the current exploration campaign will involve more extensive and extended missions requiring new concepts for lunar navigation. In contrast to Apollo missions, which were limited to the near-side equatorial region of the moon, missions under the Exploration Systems Initiative will require navigation on the moon's limb and far-side. As these regions have poor Earth visibility, a navigation system comprised solely of Earth-based tracking stations will not provide adequate navigation solutions in these areas. In this paper, a Dilution of <span class="hlt">Precision</span> (DoP) based analysis of the performance of a network of Moon orbiting satellites is provided. The analysis extends previous analysis of a Lunar Network (LN) of navigation satellites by providing an assessment of the capability associated with a variety of assumptions. These assumptions are with regard to the navigation receiver and satellite visibility. The assessment is accomplished by making appropriately formed estimates of DoP. Different adaptations of DoP (i.e. GDoP, PDoP, etc.) are associated with a different set of assumptions regarding augmentations to the navigation receiver or transceiver. A significant innovation described in this paper is the "Generalized" Dilution of <span class="hlt">Precision</span>. In the same sense that the various versions of DoP can be represented as a functional of the observability grammian, Generalized DoP is defined as a functional of the sum of observability grammians associated with a batch of radiometric measurements. Generalized DoP extends the DoP concept to cases in which radiometric range and range-rate measurements are integrated over time to develop an estimate of user <span class="hlt">position</span> (referred to here as a 'dynamic' solution.) Generalized DoP allows for the inclusion of cases in which the receiver location is underdetermined when assessed in the usual 'kinematic' sense. The Generalized DoP concept is thereby a method to assess the navigation capability associated with constellations with sparse coverage. This alleviates the burden of performing a full "covariance analysis" for each <span class="hlt">point</span> on the surface of the Moon.</p> <div class="credits"> <p class="dwt_author">Sands, Obed S.; Connolly, Joseph W.; Welch, Bryan W.; Carpenter, James R.; Ely, Todd A.; Berry, Kevin</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">154</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007SPIE.6423E.147L"> <span id="translatedtitle">Development of stewart platforms for active vibration isolation and <span class="hlt">precision</span> <span class="hlt">pointing</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Vibration isolation and extreme <span class="hlt">precision</span> <span class="hlt">pointing</span> is needed for future space telescopes, imaging sensors, laser communication, space-borne optical interferometer, and other sensitive payloads which have increased performance, depending on sustained sub-microradian <span class="hlt">pointing</span> accuracy and stability. However, the vibration sources are increased due to the large flexible structures, truss-type structures and motion devices. The spatial Stewart platform (hexapod), built by smart materials and smart structures, is a promising way to address these issues, especially for the six degree-of-freedom control purpose, since the platform offers several advantages over the serial counterparts and other methods. Jet Propulsion Laboratory (JPL), Air Force Research Laboratory (AFRL), Naval Postgraduate School (NPS), University of Washington, the Hexapod Research Group of University of Wyoming, CSA Engineering Inc, Honeywell Satellite Systems Operation and other groups have done a lot of research, this paper provides a representative look at the state-of-the-art technology and research in active vibration isolation and <span class="hlt">precision</span> <span class="hlt">pointing</span> applied in space.</p> <div class="credits"> <p class="dwt_author">Liu, Lei; Wang, Benli</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">155</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22778582"> <span id="translatedtitle">A high <span class="hlt">precision</span> <span class="hlt">position</span> sensor design and its signal processing algorithm for a maglev train.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">High <span class="hlt">precision</span> <span class="hlt">positioning</span> technology for a kind of high speed maglev train with an electromagnetic suspension (EMS) system is studied. At first, the basic structure and functions of the <span class="hlt">position</span> sensor are introduced and some key techniques to enhance the <span class="hlt">positioning</span> <span class="hlt">precision</span> are designed. Then, in order to further improve the <span class="hlt">positioning</span> signal quality and the fault-tolerant ability of the sensor, a new kind of discrete-time tracking differentiator (TD) is proposed based on nonlinear optimal control theory. This new TD has good filtering and differentiating performances and a small calculation load. It is suitable for real-time signal processing. The stability, convergence property and frequency characteristics of the TD are studied and analyzed thoroughly. The delay constant of the TD is figured out and an effective time delay compensation algorithm is proposed. Based on the TD technology, a filtering process is introduced in to improve the <span class="hlt">positioning</span> signal waveform when the sensor is under bad working conditions, and a two-sensor switching algorithm is designed to eliminate the <span class="hlt">positioning</span> errors caused by the joint gaps of the long stator. The effectiveness and stability of the sensor and its signal processing algorithms are proved by the experiments on a test train during a long-term test run. PMID:22778582</p> <div class="credits"> <p class="dwt_author">Xue, Song; Long, Zhiqiang; He, Ning; Chang, Wensen</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">156</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890000817&hterms=dynamic+positioning&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Ddynamic%2Bpositioning"> <span id="translatedtitle"><span class="hlt">Precise</span> orbit determination for NASA's earth observing system using GPS (Global <span class="hlt">Positioning</span> System)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">An application of a <span class="hlt">precision</span> orbit determination technique for NASA's Earth Observing System (EOS) using the Global <span class="hlt">Positioning</span> System (GPS) is described. This technique allows the geometric information from measurements of GPS carrier phase and P-code pseudo-range to be exploited while minimizing requirements for <span class="hlt">precision</span> dynamical modeling. The method combines geometric and dynamic information to determine the spacecraft trajectory; the weight on the dynamic information is controlled by adjusting fictitious spacecraft accelerations in three dimensions which are treated as first order exponentially time correlated stochastic processes. By varying the time correlation and uncertainty of the stochastic accelerations, the technique can range from purely geometric to purely dynamic. Performance estimates for this technique as applied to the orbit geometry planned for the EOS platforms indicate that decimeter accuracies for EOS orbit <span class="hlt">position</span> may be obtainable. The sensitivity of the predicted orbit uncertainties to model errors for station locations, nongravitational platform accelerations, and Earth gravity is also presented.</p> <div class="credits"> <p class="dwt_author">Williams, B. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">157</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1616331Z"> <span id="translatedtitle">Preliminary assessment of the basic navigation and <span class="hlt">precise</span> <span class="hlt">positioning</span> performance of BDS</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Following the general guideline of starting with regional services and then expanding to global services, the BeiDou Navigation Satellite System(BDS) is steadily accelerating the construction. By the end of 2012, the BDS already consists of fourteen networking satellites, including five GEO satellites, five IGSO satellites, and four MEO satellites, and owns full operational capability for China and its surrounding areas. Both basic navigation and <span class="hlt">precise</span> <span class="hlt">positioning</span> performance of current BDS (with 5GEO+5IGSO+4MEO satellites) during January to December of 2013 are evaluated in this presentation. In China and its surrounding area, the <span class="hlt">positioning</span> accuracy using BDS opening service is about 10 meters in both horizontal and vertical direction. Users can get high <span class="hlt">precise</span> service using BDS only, and both BDS and GPS users can be benefitted from combination of the two systems.</p> <div class="credits"> <p class="dwt_author">Zhao, Qile; Hu, Zhigang; Li, Min; Guo, Jing; Shi, Chuang; Liu, Jingnan</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">158</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/10136166"> <span id="translatedtitle">Input shaping for three-dimensional slew maneuvers of a <span class="hlt">precision</span> <span class="hlt">pointing</span> flexible spacecraft</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A method is presented for input torque shaping for three-dimensional slew maneuvers of a <span class="hlt">precision</span> <span class="hlt">pointing</span> flexible spacecraft. The method determines the torque profiles for fixed-time, rest-to-rest maneuvers which minimizes a specified performance index. Spacecraft dynamics are formulated in such a manner that the rigid body and flexible motions are decoupled. Furthermore, assembly by making use of finite element analysis results. Input torque profiles are determined by solving an associated optimization problem using dynamic programming. Three example problems are provided to demonstrate the application of the method.</p> <div class="credits"> <p class="dwt_author">Dohrmann, C.R.; Robinett, R.D.</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">159</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5892457"> <span id="translatedtitle">Etching of deep grooves for the <span class="hlt">precise</span> <span class="hlt">positioning</span> of cleaves in semiconductor lasers</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Photoelectrochemical etching of InP is used to etch deep (80 ..mu..m), narrow (20 ..mu..m) grooves. The grooves are used to <span class="hlt">precisely</span> <span class="hlt">position</span> cleaves in semiconductor lasers and to demonstrate the first wafer processing of long/short cleaved-coupled-cavity (C/sup 3/) lasers. Large numbers of low threshold C/sup 3/ lasers wth very similar cavity lengths were obtained.</p> <div class="credits"> <p class="dwt_author">Bowers, J.E.; Hemenway, B.R.; Wilt, D.P.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">160</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51119250"> <span id="translatedtitle">Trajectory planning and control for <span class="hlt">precision</span> <span class="hlt">positioning</span> table driven by a PMSM</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In this paper, we propose a novel trajectory planning method for a <span class="hlt">precision</span> <span class="hlt">positioning</span> table driven by a permanent magnet synchronous motor (PMSM). To generate the mechatronic trajectory we develop a real-coded genetic algorithm (RGA) to search for the optimal trajectory for the motion. In this method, we design a high-degree polynomial to compute minimum-energy trajectories, and consider the problem</p> <div class="credits"> <p class="dwt_author">Yi-Lung Hsu; Ming-Shyan Huang; Rong-Fong Fung</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_7");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a 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showDiv("page_10");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">161</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/39928631"> <span id="translatedtitle">Airborne vector gravimetry using <span class="hlt">precise</span>, <span class="hlt">position</span>-aided inertial measurement units</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Vector gravimetry using a <span class="hlt">precise</span> inertial navigation system continually updated with external <span class="hlt">position</span> data, for example\\u000a using GPS, is studied with respect to two problems. The first concerns the attitude accuracy requirement for horizontal gravity\\u000a component estimation. With covariance analyses in the space and frequency domains it is argued that with relatively stable\\u000a uncompensated gyro drift, the short-wavelength gravity vector</p> <div class="credits"> <p class="dwt_author">Christopher Jekeli</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">162</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/11711687"> <span id="translatedtitle">Accuracy, <span class="hlt">precision</span>, and quality control for <span class="hlt">point</span>-of-care testing of oral anticoagulation.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Oral anticoagulant (OAC) therapy is usually monitored by noting changes in a tissue factor-induced coagulation time ("prothrombin time") test on whole blood or plasma and expressed as an International Normalized Ratio (INR). Current <span class="hlt">point</span>-of-care (POC) instruments for monitoring OAC therapy display both the calculated prothrombin time (PT) and the INR. Although many attempts have been made to improve the accuracy and <span class="hlt">precision</span> of INR determinations in daily practice, it is impossible to eliminate all uncertainty because the PT test is sensitive to multiple factors in the patient's blood specimen. The accuracy of the average INR determined with a POC instrument depends on its calibration against reference methods. Quality control (QC) materials for POC devices are different from patients' samples and may not exactly reflect the real clinical situation. Nevertheless, internal and external QC schemes for POC devices are valuable to investigate their performance in daily practice. Calibration can be improved by direct comparison of a POC system against an established international reference preparation method. In general, the <span class="hlt">precision</span> of the INR measured with a POC device is slightly lower than the <span class="hlt">precision</span> achieved with available automated laboratory instruments. The greater imprecision should be weighed against the clinical advantages of a POC testing device. PMID:11711687</p> <div class="credits"> <p class="dwt_author">van den Besselaar, A M</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">163</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003AIPC..680.1138K"> <span id="translatedtitle">The Use of Industrial Robot Arms for High <span class="hlt">Precision</span> Patient <span class="hlt">Positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Indiana University Cyclotron Facility (IUCF) is in the process of designing and building the Midwest Proton Radiation Institute (MPRI) [1]. The design process includes the development of several patient treatment systems. This paper discusses the use of two such systems that provide for the high <span class="hlt">precision</span> <span class="hlt">positioning</span> of a patient. They are the Patient Positioner System and the X-ray system. The Patient Positioner System <span class="hlt">positions</span> an immobilized patient on a support device to a treatment <span class="hlt">position</span> based on a prescribed Treatment Plan. The X-ray system uses an industrial robot arm to <span class="hlt">position</span> a Digital Radiography Panel to acquire an X-ray image to verify the location of the prescribed treatment volume in a patient by comparing the acquired images with reference images obtained from the patient's Treatment plan.</p> <div class="credits"> <p class="dwt_author">Katuin, J. E.; Schreuder, A. N.; Starks, W. M.; Doskow, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">164</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013SPIE.9046E..1FW"> <span id="translatedtitle">Optimized laser beam widths meter calibration system: <span class="hlt">precisely</span> <span class="hlt">positioning</span> of detector measurement plane</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The direct substitution method is used in the laser beam widths meter (usually the laser beam profiler) calibration. The laser beam widths measurement results of device under test (DUT) are compared with those made by the laboratory standard. For most laser beam widths meter, the detector measurement plane is installed inside detector head, so it is difficult to accurately <span class="hlt">position</span> the measurement plane for both standard and DUT. Depending on the ocular estimation, the difference of measurement plane between standard and DUT is usually controlled within 5mm. For 2.5mrad divergence angle of laser beam, 5mm tolerance will cause an uncertainty of 12.5?m in the beam widths measurement. In the optimized calibration system, a wedge prism placed in the beam path produces a <span class="hlt">precise</span> beam deflection, which results in the laser spot displacement on the measurement plane. Depending on the measurable displacement of beam centroid <span class="hlt">position</span> and the beam deflection angle, the distance from the wedge prism to the detector measurement plane is determined. The experimental results show that using the measurement plane <span class="hlt">positioning</span> method, the difference of measurement plane between standard and DUT is close to 80?m, only contributing an uncertainty of 0.125?m in final result with the same 2.5mrad beam divergence angle. In additional, some factors affecting <span class="hlt">precisely</span> <span class="hlt">positioning</span> of measurement plane are analyzed in this paper.</p> <div class="credits"> <p class="dwt_author">Wang, Yanping; Wang, Qianqian; Ma, Chong</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">165</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19910008996&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle">Demonstration of <span class="hlt">precise</span> estimation of polar motion parameters with the global <span class="hlt">positioning</span> system: Initial results</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Data from the Global <span class="hlt">Positioning</span> System (GPS) were used to determine <span class="hlt">precise</span> polar motion estimates. Conservatively calculated formal errors of the GPS least squares solution are approx. 10 cm. The GPS estimates agree with independently determined polar motion values from very long baseline interferometry (VLBI) at the 5 cm level. The data were obtained from a partial constellation of GPS satellites and from a sparse worldwide distribution of ground stations. The accuracy of the GPS estimates should continue to improve as more satellites and ground receivers become operational, and eventually a near real time GPS capability should be available. Because the GPS data are obtained and processed independently from the large radio antennas at the Deep Space Network (DSN), GPS estimation could provide very <span class="hlt">precise</span> measurements of Earth orientation for calibration of deep space tracking data and could significantly relieve the ever growing burden on the DSN radio telescopes to provide Earth platform calibrations.</p> <div class="credits"> <p class="dwt_author">Lichten, S. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">166</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005SPIE.5899...13D"> <span id="translatedtitle"><span class="hlt">Precision</span> telescope <span class="hlt">pointing</span> and spacecraft vibration isolation for the Terrestrial Planet Finder Coronagraph</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Terrestrial Planet Finder Coronagraph is a visible-light coronagraph to detect planets that are orbiting within the Habitable Zone of stars. The coronagraph instrument must achieve a contrast ratio stability of 2e-11 in order to achieve planet detection. This places stringent requirements on several spacecraft subsystems, such as <span class="hlt">pointing</span> stability and structural vibration of the instrument in the presence of mechanical disturbance: for example, telescope <span class="hlt">pointing</span> must be accurate to within 4 milli-arcseconds, and the jitter of optics must be less than 5 nm. This paper communicates the architecture and predicted performance of a <span class="hlt">precision</span> <span class="hlt">pointing</span> and vibration isolation approach for TPF-C called Disturbance Free Payload (DFP)* . In this architecture, the spacecraft and payload fly in close-proximity, and interact with forces and torques through a set of non-contact interface sensors and actuators. In contrast to other active vibration isolation approaches, this architecture allows for isolation down to zero frequency, and the performance of the isolation system is not limited by sensor characteristics. This paper describes the DFP architecture, interface hardware and technical maturity of the technology. In addition, an integrated model of TPF-C Flight Baseline 1 (FB1) is described that allows for explicit computation of performance metrics from system disturbance sources. Using this model, it is shown that the DFP <span class="hlt">pointing</span> and isolation architecture meets all <span class="hlt">pointing</span> and jitter stability requirements with substantial margin. This performance relative to requirements is presented, and several fruitful avenues for utilizing performance margin for system design simplification are identified.</p> <div class="credits"> <p class="dwt_author">Dewell, Larry; Pedreiro, Nelson; Blaurock, Carl; Liu, Kuo-Chia; Alexander, James; Levine, Marie</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">167</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AdSpR..52..466C"> <span id="translatedtitle">DORIS-based <span class="hlt">point</span> mascons for the long term stability of <span class="hlt">precise</span> orbit solutions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In recent years non-tidal Time Varying Gravity (TVG) has emerged as the most important contributor in the error budget of <span class="hlt">Precision</span> Orbit Determination (POD) solutions for altimeter satellites' orbits. The Gravity Recovery And Climate Experiment (GRACE) mission has provided POD analysts with static and time-varying gravity models that are very accurate over the 2002-2012 time interval, but whose linear rates cannot be safely extrapolated before and after the GRACE lifespan. One such model based on a combination of data from GRACE and Lageos from 2002-2010, is used in the dynamic POD solutions developed for the Geophysical Data Records (GDRs) of the Jason series of altimeter missions and the equivalent products from lower altitude missions such as Envisat, Cryosat-2, and HY-2A. In order to accommodate long-term time-variable gravity variations not included in the background geopotential model, we assess the feasibility of using DORIS data to observe local mass variations using <span class="hlt">point</span> mascons. In particular, we show that the <span class="hlt">point</span>-mascon approach can stabilize the geographically correlated orbit errors which are of fundamental interest for the analysis of regional Mean Sea Level trends based on altimeter data, and can therefore provide an interim solution in the event of GRACE data loss. The time series of <span class="hlt">point</span>-mass solutions for Greenland and Antarctica show good agreement with independent series derived from GRACE data, indicating a mass loss at rate of 210 Gt/year and 110 Gt/year respectively.</p> <div class="credits"> <p class="dwt_author">Cerri, L.; Lemoine, J. M.; Mercier, F.; Zelensky, N. P.; Lemoine, F. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">168</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013ISPAr.XL1b.113E"> <span id="translatedtitle">A <span class="hlt">Precise</span> <span class="hlt">Position</span> and Attitude Determination System for Lightweight Unmanned Aerial Vehicles</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In many unmanned aerial vehicle (UAV) applications a direct georeferencing is required. The reason can be that the UAV flies autonomous and must be navigated <span class="hlt">precisely</span>, or that the UAV performs a remote sensing operation, where the <span class="hlt">position</span> of the camera has to be known at the moment of the recording. In our application, a project called Mapping on Demand, we are motivated by both of these reasons. The goal of this project is to develop a lightweight autonomously flying UAV that is able to identify and measure inaccessible three-dimensional objects by use of visual information. Due to payload and space limitations, <span class="hlt">precise</span> <span class="hlt">position</span> and attitude determination of micro- and mini-sized UAVs is very challenging. The limitations do not only affect the onboard computing capacity, but they are also noticeable when choosing the georeferencing sensors. In this article, we will present a new developed onboard direct georeferencing system which is real-time capable, applicable for lightweight UAVs and provides very <span class="hlt">precise</span> results (<span class="hlt">position</span> accuracy ? < 5 cm and attitude accuracy ? < 0.5 deg). In this system GPS, inertial sensors, magnetic field sensors, a barometer as well as stereo video cameras are used as georeferencing sensors. We will describe the hardware development and will go into details of the implemented software. In this context especially the RTK-GPS software and the concept of the attitude determination by use of inertial sensors, magnetic field sensors as well as an onboard GPS baseline will be highlighted. Finally, results of first field tests as well as an outlook on further developments will conclude this contribution.</p> <div class="credits"> <p class="dwt_author">Eling, C.; Klingbeil, L.; Wieland, M.; Kuhlmann, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">169</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19940009898&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle">Improved treatment of global <span class="hlt">positioning</span> system force parameters in <span class="hlt">precise</span> orbit determination applications</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Data collected from a worldwide 1992 experiment were processed at JPL to determine <span class="hlt">precise</span> orbits for the satellites of the Global <span class="hlt">Positioning</span> System (GPS). A filtering technique was tested to improve modeling of solar-radiation pressure force parameters for GPS satellites. The new approach improves orbit quality for eclipsing satellites by a factor of two, with typical results in the 25- to 50-cm range. The resultant GPS-based estimates for geocentric coordinates of the tracking sites, which include the three DSN sites, are accurate to 2 to 8 cm, roughly equivalent to 3 to 10 nrad of angular measure.</p> <div class="credits"> <p class="dwt_author">Vigue, Y.; Lichten, S. M.; Muellerschoen, R. J.; Blewitt, G.; Heflin, M. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">170</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010SPIE.7731E..54P"> <span id="translatedtitle">Achieving high-<span class="hlt">precision</span> <span class="hlt">pointing</span> on ExoplanetSat: initial feasibility analysis</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">ExoplanetSat is a proposed three-unit CubeSat designed to detect down to Earth-sized exoplanets in an orbit out to the habitable zone of Sun-like stars via the transit method. To achieve the required photometric <span class="hlt">precision</span> to make these measurements, the target star must remain within the same fraction of a pixel, which is equivalent to controlling the <span class="hlt">pointing</span> of the satellite to the arcsecond level. The satellite will use a two-stage control system: coarse control will be performed by a set of reaction wheels, desaturated by magnetic torque coils, and fine control will be performed by a piezoelectric translation stage. Since no satellite of this size has previously demonstrated this high level of <span class="hlt">pointing</span> <span class="hlt">precision</span>, a simulation has been developed to prove the feasibility of realizing such a system. The current baseline simulation has demonstrated the ability to hold the target star to within 0.05 pixels or 1.8 arcseconds (with an 85 mm lens and 15 ?m pixels), in the presence of large reaction wheel disturbances as well as external environmental disturbances. This meets the current requirement of holding the target star to 0.14 pixels or 5.0 arcseconds. Other high-risk aspects of the design have been analyzed such as the effect of changing the guide star centroiding error, changing the CMOS sampling frequency, and reaction wheel selection on the slew performance of the satellite. While these results are promising as an initial feasibility analysis, further model improvements and hardware-in-the-loop tests are currently underway.</p> <div class="credits"> <p class="dwt_author">Pong, Christopher M.; Lim, Sungyung; Smith, Matthew W.; Miller, David W.; Villaseñor, Jesus S.; Seager, Sara</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">171</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20060008640&hterms=source+level&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsource%2Blevel"> <span id="translatedtitle">Track-Level-Compensation Look-Up Table Improves Antenna <span class="hlt">Pointing</span> <span class="hlt">Precision</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This article presents the improvement of the beam-waveguide antenna <span class="hlt">pointing</span> accuracy due to the implementation of the track-level-compensation look-up table. It presents the development of the table, from the measurements of the inclinometer tilts to the processing of the measurement data and the determination of the threeaxis alidade rotations. The table consists of three axis rotations of the alidade as a function of the azimuth <span class="hlt">position</span>. The article also presents the equations to determine the elevation and cross-elevation errors of the antenna as a function of the alidade rotations and the antenna azimuth and elevation <span class="hlt">positions</span>. The table performance was verified using radio beam <span class="hlt">pointing</span> data. The <span class="hlt">pointing</span> error decreased from 4.5 mdeg to 1.4 mdeg in elevation and from 14.5 mdeg to 3.1 mdeg in cross-elevation. I. Introduction The Deep Space Station 25 (DSS 25) antenna shown in Fig. 1 is one of NASA s Deep Space Network beam-waveguide (BWG) antennas. At 34 GHz (Ka-band) operation, it is necessary to be able to track with a <span class="hlt">pointing</span> accuracy of 2-mdeg root-mean-square (rms). Repeatable <span class="hlt">pointing</span> errors of several millidegrees of magnitude have been observed during the BWG antenna calibration measurements. The systematic errors of order 4 and lower are eliminated using the antenna <span class="hlt">pointing</span> model. However, repeatable <span class="hlt">pointing</span> errors of higher order are out of reach of the model. The most prominent high-order systematic errors are the ones caused by the uneven azimuth track. The track is shown in Fig. 2. Manufacturing and installation tolerances, as well as gaps between the segments of the track, are the sources of the <span class="hlt">pointing</span> errors that reach over 14-mdeg peak-to-peak magnitude, as reported in [1,2]. This article presents a continuation of the investigations and measurements of the <span class="hlt">pointing</span> errors caused by the azimuth-track-level unevenness that were presented in [1] and [2], and it presents the implementation results. Track-level-compensation (TLC) look-up tables were created for the DSS 25, DSS 26, DSS 34, and DSS 55 antennas. To date, the most complete and detailed results were obtained for the DSS 25 and DSS 55 antennas. In this article, for brevity of presentation, we present the DSS 25 antenna results only. 1 Communications Ground Systems Section. The research described in this publication was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.</p> <div class="credits"> <p class="dwt_author">Gawronski, W.; Baher, F.; Gama, E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">172</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AdSpR..51.1065R"> <span id="translatedtitle">Libration <span class="hlt">point</span> orbits for lunar global <span class="hlt">positioning</span> systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">With the development of lunar exploration, a lunar global <span class="hlt">positioning</span> system (LGPS) is demanded for both on-ground and in-flight lunar exploration missions. The traditional configuration of constellation requires at least eighteen satellites to cover the whole lunar surface continuously. In this paper, the configurations of the libration <span class="hlt">point</span> orbits (LPOs) constellations are investigated. By using the constellations on the Earth-Moon L1 and L2 LPOs, the basic functions of the LGPS can be realized by using eight to fourteen satellites. First, the LPO and the combinations of LPOs, which can be used in the constellations of the LGPS, are investigated. The criteria and procedures of the configuration design are introduced. Second, the configurations of LPOs constellations are investigated in the Earth-Moon circular-restricted three-body problem (CR3BP). The size of the LPOs and the distribution of the satellites on these LPOs are determined by using an exhaustive algorithm and a global optimization method, respectively. The key performance parameters of these constellations are computed. Third, the constellations with good performance in the CR3BP are redesigned in the more accurate Earth-Moon based Sun-perturbed bicircular four-body problem (B4BP). Moreover, in order to avoid the ground coverage problem caused by the perturbation of the Sun, some modifications are implemented, and the configuration of the no blind area LGPS in the B4BP is obtained.</p> <div class="credits"> <p class="dwt_author">Ren, Yuan; Shan, Jinjun</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">173</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012SPIE.8412E..16A"> <span id="translatedtitle">High <span class="hlt">precision</span> analysis of variations in self image quality and <span class="hlt">position</span> with Multimode Interference (MMI) device width</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Multimode Interference (MMI) device is a useful optical component for optical power splitter/combiner and router applications. In this paper we present high <span class="hlt">precision</span> calculation results on the optimum <span class="hlt">position</span> of self-images in an MMI and their variation due to wavelengths, for WDM applications. We show that the commonly used MMI self-image <span class="hlt">position</span> calculation methods, using the beat length of two lowest order modes or effective MMI width approximation, lead to significant deviations from the optimum self-image <span class="hlt">position</span>. We calculate the optimum <span class="hlt">position</span> of the self-image by finding the maximum value of overlap integral of total MMI field, comprised of all MMI modes, with the total field at the input of the MMI device. In addition, for the optimum output power coupling distance for MMI, we calculate the overlap integral of the total MMI field with the output waveguide field. Both these methods give approximately the same optimum length. We obtain up to 60 um difference in optimum self-image <span class="hlt">position</span> for a Si MMI (width =15 ~ 30 um), and refractive index difference of 0.02 between core and cladding, from the approximations based methods. We also calculate the variation of this image <span class="hlt">position</span> in 1.50 um to 1.60 um wavelength region. We show that the optimum image <span class="hlt">position</span> is strongly dependent on wavelength, with up to 100 um variations in this wavelength range. In addition, we show that there is a significant variation in this self image <span class="hlt">position</span> with MMI widths, at <span class="hlt">points</span> where a new power carrying mode is added.</p> <div class="credits"> <p class="dwt_author">Azfar, Talal; Amin, Sundas; Malik, Beena</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">174</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22163417"> <span id="translatedtitle">An integration of GPS with INS sensors for <span class="hlt">precise</span> long-baseline kinematic <span class="hlt">positioning</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Integrating the <span class="hlt">precise</span> GPS carrier phases and INS sensor technologies is a methodology that has been applied indispensably in those application fields requiring accurate and reliable <span class="hlt">position</span>, velocity, and attitude information. However, conventional integration approaches with a single GPS reference station may not fulfil the demanding performance requirements, especially in the <span class="hlt">position</span> component, when the baseline length between the reference station and mobile user's GPS receiver is greater than a few tens of kilometres. This is because their <span class="hlt">positioning</span> performance is primarily dependent on the common mode of errors of GPS measurements. To address this constraint, a novel GPS/INS integration scheme using multiple GPS reference stations is proposed here that can improve its <span class="hlt">positioning</span> accuracy by modelling the baseline-dependent errors. In this paper, the technical issues concerned with implementing the proposed scheme are described, including the GPS network correction modelling and integrated GPS/INS filtering. In addition, the results from the processing of the simulated measurements are presented to characterise the system performance. As a result, it has been established that the integration of GPS/INS with multiple reference stations would make it possible to ensure centimetre-level <span class="hlt">positioning</span> accuracy, even if the baseline length reaches about 100 km. PMID:22163417</p> <div class="credits"> <p class="dwt_author">Lee, Hungkyu</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">175</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/12425"> <span id="translatedtitle">Vibratory response modeling and verification of a high <span class="hlt">precision</span> optical <span class="hlt">positioning</span> system.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A generic vibratory-response modeling program has been developed as a tool for designing high-<span class="hlt">precision</span> optical <span class="hlt">positioning</span> systems. Based on multibody dynamics theory, the system is modeled as rigid-body structures connected by linear elastic elements, such as complex actuators and bearings. The full dynamic properties of each element are determined experimentally or theoretically, then integrated into the program as inertial and stiffness matrices. Utilizing this program, the theoretical and experimental verification of the vibratory behavior of a double-multilayer monochromator support and <span class="hlt">positioning</span> system is presented. Results of parametric design studies that investigate the influence of support floor dynamics and highlight important design issues are also presented. Overall, good matches between theory and experiment demonstrate the effectiveness of the program as a dynamic modeling tool.</p> <div class="credits"> <p class="dwt_author">Barraza, J.; Kuzay, T.; Royston, T. J.; Shu, D.</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-06-18</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">176</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013RScI...84i3303E"> <span id="translatedtitle">A free jet (supersonic), molecular beam source with automatized, 50 nm <span class="hlt">precision</span> nozzle-skimmer <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Low energy (thermal) free jet (supersonic) molecular beams are used in a range of applications from surface science and surface deposition to quantum coherence and gas kinetics experiments. A free jet molecular beam is created by a gas expansion from a high pressure reservoir through a small aperture (nozzle). The nozzle typically has a diameter of 2-20 ?m. The central part of the beam is selected using a skimmer, typically up to 500 ?m in diameter. Recent years have seen the introduction of highly spatially confined beam sources based on micrometer skimmers and micrometer or even sub-micrometer nozzles. Such sources have been applied, for example, in the investigation of superfluidity and in neutral helium microscopy. However, up till now no source design allowing the <span class="hlt">precise</span> <span class="hlt">positioning</span> of the micro-skimmer relative to the nozzle has been available. This is an important issue because the relative <span class="hlt">position</span> of skimmer and nozzle can influence the beam properties considerably. Here we present the design and implementation of a new molecular beam source, which allows an automatized, 50 nm <span class="hlt">precision</span> <span class="hlt">positioning</span> of the skimmer relative to the nozzle. The source is liquid nitrogen cooled and the temperature can be controlled between 110 K and 350 K with a temperature fluctuation of less than +/-0.1 K over several hours. Beam intensity measurements using a 5 ?m nozzle and a skimmer 5 ?m in diameter are presented for stagnation pressures po in the range 3-180 bars. A 2D beam profile scan, using a 9.5 ?m skimmer and a 5 ?m nozzle is presented as a further documentation of the versatility of the new design and as an illustration of the influence of the relative skimmer-nozzle <span class="hlt">position</span> on the beam properties.</p> <div class="credits"> <p class="dwt_author">Eder, S. D.; Samelin, B.; Bracco, G.; Ansperger, K.; Holst, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">177</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24089819"> <span id="translatedtitle">A free jet (supersonic), molecular beam source with automatized, 50 nm <span class="hlt">precision</span> nozzle-skimmer <span class="hlt">positioning</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Low energy (thermal) free jet (supersonic) molecular beams are used in a range of applications from surface science and surface deposition to quantum coherence and gas kinetics experiments. A free jet molecular beam is created by a gas expansion from a high pressure reservoir through a small aperture (nozzle). The nozzle typically has a diameter of 2-20 ?m. The central part of the beam is selected using a skimmer, typically up to 500 ?m in diameter. Recent years have seen the introduction of highly spatially confined beam sources based on micrometer skimmers and micrometer or even sub-micrometer nozzles. Such sources have been applied, for example, in the investigation of superfluidity and in neutral helium microscopy. However, up till now no source design allowing the <span class="hlt">precise</span> <span class="hlt">positioning</span> of the micro-skimmer relative to the nozzle has been available. This is an important issue because the relative <span class="hlt">position</span> of skimmer and nozzle can influence the beam properties considerably. Here we present the design and implementation of a new molecular beam source, which allows an automatized, 50 nm <span class="hlt">precision</span> <span class="hlt">positioning</span> of the skimmer relative to the nozzle. The source is liquid nitrogen cooled and the temperature can be controlled between 110 K and 350 K with a temperature fluctuation of less than ±0.1 K over several hours. Beam intensity measurements using a 5 ?m nozzle and a skimmer 5 ?m in diameter are presented for stagnation pressures po in the range 3-180 bars. A 2D beam profile scan, using a 9.5 ?m skimmer and a 5 ?m nozzle is presented as a further documentation of the versatility of the new design and as an illustration of the influence of the relative skimmer-nozzle <span class="hlt">position</span> on the beam properties. PMID:24089819</p> <div class="credits"> <p class="dwt_author">Eder, S D; Samelin, B; Bracco, G; Ansperger, K; Holst, B</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">178</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3444124"> <span id="translatedtitle">Design and Analysis of a Compact <span class="hlt">Precision</span> <span class="hlt">Positioning</span> Platform Integrating Strain Gauges and the Piezoactuator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Miniaturization <span class="hlt">precision</span> <span class="hlt">positioning</span> platforms are needed for in situ nanomechanical test applications. This paper proposes a compact <span class="hlt">precision</span> <span class="hlt">positioning</span> platform integrating strain gauges and the piezoactuator. Effects of geometric parameters of two parallel plates on Von Mises stress distribution as well as static and dynamic characteristics of the platform were studied by the finite element method. Results of the calibration experiment indicate that the strain gauge sensor has good linearity and its sensitivity is about 0.0468 mV/?m. A closed-loop control system was established to solve the problem of nonlinearity of the platform. Experimental results demonstrate that for the displacement control process, both the displacement increasing portion and the decreasing portion have good linearity, verifying that the control system is available. The developed platform has a compact structure but can realize displacement measurement with the embedded strain gauges, which is useful for the closed-loop control and structure miniaturization of piezo devices. It has potential applications in nanoindentation and nanoscratch tests, especially in the field of in situ nanomechanical testing which requires compact structures.</p> <div class="credits"> <p class="dwt_author">Huang, Hu; Zhao, Hongwei; Yang, Zhaojun; Fan, Zunqiang; Wan, Shunguang; Shi, Chengli; Ma, Zhichao</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">179</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.7119S"> <span id="translatedtitle">Influence of the TEC fluctuations in the polar region on <span class="hlt">precise</span> GPS <span class="hlt">positioning</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The ionospheric delay is an atmoshperic effect influencing on Global Navigation Satellite System signals. On the one hand it is a factor limiting the accuracy of the GNSS <span class="hlt">positioning</span>, and on the other it makes satellite observations a very good source of the information on the ionospheric conditions. The degradation of the relative <span class="hlt">positioning</span> accuracy and reliability can be connected with high gradients of the total electron content or with the TEC fluctuations. The latter of these effects mainly occurs in the equatorial and polar regions. The ionosphere near the geomagnetic poles is characterized by relatively small TEC values in comparison to the other regions. However, the connection between the magnetosphere and ionosphere systems in the polar regions allows particle precipitation and leads to very strong ionospheric dynamics. In this work, performance of the GNSS <span class="hlt">precise</span> relative <span class="hlt">positioning</span> under disturbed ionospheric conditions in the northern polar region is studied. The test results are based on processing 24-hour data sets from the selected permanent GPS stations located in Greenland. The studies cover several days of high and low solar activity, and also periods of a geomagnetic storm characterized by intensive TEC fluctuations. The data processing was carried out in static and kinematic modes. The GINPOS software developed at the University of Warmia and Mazury in Olsztyn was used for <span class="hlt">positioning</span> tests. The study confirms and presents the influence of the ionospheric and geomagnetic activity in the polar region on the results in coordinate and ambiguity domains.</p> <div class="credits"> <p class="dwt_author">Sieradzki, Rafal; Paziewski, Jacek; Wielgosz, Pawel</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">180</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53126134"> <span id="translatedtitle">A <span class="hlt">precise</span> <span class="hlt">pointing</span> technique for free space optical links and networks using kinematic GPS and local sensors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In free space optical (FSO) communication networks, <span class="hlt">pointing</span>, acquisition, and tracking (PAT) techniques are needed to establish and maintain optical links among the static or mobile nodes in the network. First, this paper describes a <span class="hlt">precise</span> <span class="hlt">pointing</span> technique to steer the local directional laser beam of an optical transceiver to a target optical transceiver at a remote transceiver node. The</p> <div class="credits"> <p class="dwt_author">Yohan Shim; Stuart D. Milner; Christopher C. Davis</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_8");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">181</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011SCPMA..54.1059Z"> <span id="translatedtitle">Global modeling 2nd-order ionospheric delay and its effects on GNSS <span class="hlt">precise</span> <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Ionospheric delay is one of the major error sources in GNSS navigation and <span class="hlt">positioning</span>. Nowadays, the dual-frequency technique is the most widely used in ionospheric refraction correction. However, dual-frequency measurements can only eliminate the first-order term of ionospheric delay, while the effect of the second-order term on GNSS observations may be several centimeters. In this paper, two models, the International Reference Ionosphere (IRI) 2007 and International Geomagnetic Reference Field (IGRF) 11 are used to estimate the second-order term through the integral calculation method. Besides, the simplified single layer ionosphere model in a dipole moment approximation for the earth magnetic field is used. Since the traditional integral calculation method requires large calculation load and takes much time, it is not convenient for practical use. Additionally, although the simplified single layer ionosphere model is simple to implement, it results in larger errors. In this study, second-order term ionospheric correction formula proposed by Hoque (2007) is improved for estimating the second-order term at a global scale. Thus, it is more practicable to estimate the second-order term. More importantly, its results have a higher <span class="hlt">precision</span> of the sub-millimeter level for a global scale in normal conditions. Compared with Hoque's original regional correction model, which calculates coefficients through polynomial fitting of elevation and latitudes, this study proposes a piece-wise look-up table and interpolation technique to modify Hoque model. Through utilizing a table file, the modified Hoque model can be conveniently implemented in an engineering software package, like as PANDA in this study. Through applying the proposed scheme for the second-order ionospheric correction into GNSS <span class="hlt">precise</span> <span class="hlt">positioning</span> in both PPP daily and epoch solutions, the results have shown south-shift characteristics in daily solution at a global scale and periodic change with VTEC daily variation in epoch <span class="hlt">positioning</span> solution.</p> <div class="credits"> <p class="dwt_author">Zhang, Hongping; Lv, Haixia; Li, Min; Shi, Chuang</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">182</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/6096135"> <span id="translatedtitle">A 145-base pair DNA sequence that <span class="hlt">positions</span> itself <span class="hlt">precisely</span> and asymmetrically on the nucleosome core.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">A 145-bp DNA sequence, cloned from Escherichia coli, was reconstituted into nucleosome core particles by a number of methods. The behaviour of the resulting complex upon sucrose gradient sedimentation and nucleoprotein gel electrophoresis closely resembled that of control bulk nucleosome core particles. DNase I digestion of the 32P-end-labelled complex revealed the 10-bp periodicity of cleavages expected for DNA bound on a histone surface. The narrow cleavage sites observed (1 bp wide) imply that the sequence occupies a single preferred <span class="hlt">position</span> on the nucleosome core, accurate to the level of single base pairs. By relating the digestion pattern observed to the pattern of site protection found for random sequence nucleosomes, the DNA <span class="hlt">position</span> was found to be offset by 17 bp from that in the normal core particle. A number of experiments argue against the involvement of length or end effects and suggest that it is some feature of the DNA sequence itself that determines this <span class="hlt">precise</span> <span class="hlt">positioning</span> of DNA on the nucleosome. PMID:6096135</p> <div class="credits"> <p class="dwt_author">Ramsay, N; Felsenfeld, G; Rushton, B M; McGhee, J D</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">183</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19900039594&hterms=chong&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dchong"> <span id="translatedtitle"><span class="hlt">Precise</span> tracking of remote sensing satellites with the Global <span class="hlt">Positioning</span> System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The Global <span class="hlt">Positioning</span> System (GPS) can be applied in a number of ways to track remote sensing satellites at altitudes below 3000 km with accuracies of better than 10 cm. All techniques use a <span class="hlt">precise</span> global network of GPS ground receivers operating in concert with a receiver aboard the user satellite, and all estimate the user orbit, GPS orbits, and selected ground locations simultaneously. The GPS orbit solutions are always dynamic, relying on the laws of motion, while the user orbit solution can range from purely dynamic to purely kinematic (geometric). Two variations show considerable promise. The first one features an optimal synthesis of dynamics and kinematics in the user solution, while the second introduces a novel gravity model adjustment technique to exploit data from repeat ground tracks. These techniques, to be demonstrated on the Topex/Poseidon mission in 1992, will offer subdecimeter tracking accuracy for dynamically unpredictable satellites down to the lowest orbital altitudes.</p> <div class="credits"> <p class="dwt_author">Yunck, Thomas P.; Wu, Sien-Chong; Wu, Jiun-Tsong; Thornton, Catherine L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">184</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012NuPhS.225..232T"> <span id="translatedtitle"><span class="hlt">Precision</span> measurement of the <span class="hlt">positive</span> muon lifetime by the MuLan collaboration</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We report the result of a measurement of the <span class="hlt">positive</span> muon lifetime ?? to one part-per-million (ppm) by the MuLan collaboration using a low-energy pulsed muon beam and a segmented array of plastic scintillators to record over 2×1012 decay positrons. Two different in-vacuum muon-stopping targets were used in separate data-taking periods. The combined result gives ? (MuLan)=2196980.3(2.2) ps (1 ppm). This measurement of the muon lifetime provides the most <span class="hlt">precise</span> determination of the Fermi constant, GF (MuLan)=1.1663788(7)×10-5 GeV(0.6 ppm), and will be used to extract the capture rates of the negative muon on the proton and the deuteron in the ongoing MuCap and MuSun experiments.</p> <div class="credits"> <p class="dwt_author">Tishchenko, V.; MuLan Collaboration</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">185</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ArtSa..49...21O"> <span id="translatedtitle">GNSS <span class="hlt">positioning</span> algorithms using methods of reference <span class="hlt">point</span> indicators</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The GNSS standard <span class="hlt">positioning</span> solution determines the coordinates of the GNSS receiver and the receiver clock offset from measurements of at least four pseudoranges. For GNSS <span class="hlt">positioning</span>, a direct solution was derived for five and ten observed satellites without linearisation of the observation equations and application of the least squares method. The article presents the basic principles of methods for solving the <span class="hlt">positioning</span> problem, the formulas and their derivation. The numerical examples with simulated pseudorange data confirm the correct performance of the proposed algorithm. The presented algorithms should be further tested with real measurements in other domains of <span class="hlt">positioning</span> and navigation as well.</p> <div class="credits"> <p class="dwt_author">Oszczak, Bartlomiej</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">186</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19760004131&hterms=frusca&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2522frusca%2522"> <span id="translatedtitle">A study of attitude control concepts for <span class="hlt">precision-pointing</span> non-rigid spacecraft</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Attitude control concepts for use onboard structurally nonrigid spacecraft that must be <span class="hlt">pointed</span> with great <span class="hlt">precision</span> are examined. The task of determining the eigenproperties of a system of linear time-invariant equations (in terms of hybrid coordinates) representing the attitude motion of a flexible spacecraft is discussed. Literal characteristics are developed for the associated eigenvalues and eigenvectors of the system. A method is presented for determining the poles and zeros of the transfer function describing the attitude dynamics of a flexible spacecraft characterized by hybrid coordinate equations. Alterations are made to linear regulator and observer theory to accommodate modeling errors. The results show that a model error vector, which evolves from an error system, can be added to a reduced system model, estimated by an observer, and used by the control law to render the system less sensitive to uncertain magnitudes and phase relations of truncated modes and external disturbance effects. A hybrid coordinate formulation using the provided assumed mode shapes, rather than incorporating the usual finite element approach is provided.</p> <div class="credits"> <p class="dwt_author">Likins, P. W.</p> <p class="dwt_publisher"></p> <p class="publishDate">1975-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">187</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1993GeoRL..20.2635W"> <span id="translatedtitle"><span class="hlt">Pointed</span> water vapor radiometer corrections for accurate global <span class="hlt">positioning</span> system surveying</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Delay of the Global <span class="hlt">Positioning</span> System (GPS) signal due to atmospheric water vapor is a major source of error in GPS surveying. Improved vertical accuracy is important for sea level and polar isostasy measurements, geodesy, normal fault motion, subsidence, earthquake studies, air and ground-based gravimetry, ice dynamics, and volcanology. We conducted a GPS survey using water vapor radiometers (WVRs) <span class="hlt">pointed</span> toward GPS satellites to correct for azimuthal variations in water vapor. We report 2.6 mm vertical <span class="hlt">precision</span> on a 50-km baseline for 19 solution days. Kalman filter or least-square corrections to the same data do not account for azimuthal distribution of water vapor and are degraded by 70%.</p> <div class="credits"> <p class="dwt_author">Ware, Randolph; Rocken, Christian; Solheim, Fredrick; Van Hove, Teresa; Alber, Chris; Johnson, James</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">188</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013GeoRL..40.5677L"> <span id="translatedtitle">Temporal <span class="hlt">point</span> <span class="hlt">positioning</span> approach for real-time GNSS seismology using a single receiver</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">High-rate Global Navigation Satellite Systems (GNSS) has an increasing number of applications in geohazard monitoring. GNSS-derived displacements can provide important information for magnitude estimation and fault slip inversion, which is critical for seismic and tsunamigenic hazard mitigation. In this paper, we propose a new approach to quickly capture coseismic displacements with a single GNSS receiver in real time. The new approach can overcome the convergence problem of <span class="hlt">precise</span> <span class="hlt">point</span> <span class="hlt">positioning</span>, and also avoids the integration process of the variometric approach. Using the results of the 2011 Tohoku-Oki earthquake, it is demonstrated that the proposed method can provide accurate displacement waveforms and permanent coseismic offsets at an accuracy of few centimeters, and can also reliably recover the moment magnitude and fault slip distribution.</p> <div class="credits"> <p class="dwt_author">Li, Xingxing; Ge, Maorong; Guo, Bofeng; Wickert, Jens; Schuh, Harald</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">189</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/11024277"> <span id="translatedtitle"><span class="hlt">Precisely</span> <span class="hlt">positioned</span> nucleosomes are not essential for c-fos gene regulation in vivo.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Chromatin architecture plays a decisive role in many aspects of transcription regulation. We have tested the role of specific chromatin structures in c-fos gene regulation, using a gene transfer system based on episomes derived from the Epstein-Barr virus (EBV). This system reproduces in several respects the chromatin structure and regulation of the chromosomal c-fos gene. Using this approach, we first demonstrate that the pausing of RNA polymerase II downstream of the transcriptional start site does not require <span class="hlt">precisely</span> <span class="hlt">positioned</span> nucleosomes. Indeed, changing the pattern of MNase hypersensitive sites along the transcribed sequence does not perturb RNA polymerase II pausing or the regulation of the c-fos gene. Next, we show that a putative nucleosome <span class="hlt">positioned</span> between the SIE/SRE elements (-300) and the CRE/TATA elements (-36) is not necessary for activation by a variety of inducers. Accordingly, total or partial deletion of the putative nucleosome sequence does not disturb c-fos regulation while the two regulatory sites flanking the nucleosome sequence remain hypersensitive to MNase. As described in this paper, EBV episomes are useful vectors to critically examine the role of the chromatin structure in gene transcription for human cells. PMID:11024277</p> <div class="credits"> <p class="dwt_author">Fivaz, J; Bassi, M C; Price, M; Pinaud, S; Mirkovitch, J</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-09-19</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">190</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AcAau..77..126S"> <span id="translatedtitle">The clock-aided RAIM method and it's application in improving the <span class="hlt">positioning</span> <span class="hlt">precision</span> of GPS receiver</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The prediction <span class="hlt">precision</span> of receiver clock bias (RCB) is an important factor in influencing the receiver autonomous integrity monitoring (RAIM) method augmented with it and improving GPS receiver <span class="hlt">positioning</span> <span class="hlt">precision</span>. According to the characters of the RCB series, a new prediction model in discrete grey form is presented in this paper, and then the initial value of the model is determined by establishing unconstrained optimised formula. The prediction model is utilised to augment RAIM method in order to identify faulty satellite and improve the <span class="hlt">positioning</span> <span class="hlt">precision</span> of GPS receiver. Experimental results show that the prediction model is fit for predicting the RCB series, and the RAIM method aided by it is feasible. The auxiliary RAIM method can not only enhance the efficiency of identifying faulty satellite, but also improve the <span class="hlt">positioning</span> <span class="hlt">precision</span> of GPS receiver obviously.</p> <div class="credits"> <p class="dwt_author">Shi, Yibing; Teng, Yunlong</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">191</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003ASPC..295..156H"> <span id="translatedtitle">The Digital Zenith Camera TZK2-D - A Modern High-<span class="hlt">Precision</span> Geodetic Instrument for Automatic Geographic <span class="hlt">Positioning</span> in Real-Time</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The digital zenith camera TZK2-D is a geodetic state-of-the-art instrument for determining geographic longitude and latitude fully automatically. Using CCD technology for imaging stars and a GPS-receiver for <span class="hlt">precise</span> time measurement, this instrument allows real-time geographic <span class="hlt">positioning</span> with an accuracy of 0.2 seconds of arc. The digital zenith camera is used for fast and high-<span class="hlt">precision</span> determination of the plumb line and its vertical deflection applied for the local gravity field determination in geodesy. In astronomy, high-<span class="hlt">precision</span> <span class="hlt">pointing</span> of large telescopes can be supported by the knowledge of the plumb line and its vertical deflection provided by the digital zenith camera in combination with a GPS receiver.</p> <div class="credits"> <p class="dwt_author">Hirt, C.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">192</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005APS..MARL33006C"> <span id="translatedtitle"><span class="hlt">Precise</span> equation of state measurements of ^4He near the ?-<span class="hlt">point</span>, using dual-mode Superconducting Cavity Stabilized Oscillators</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We report on progress towards <span class="hlt">precise</span> equation of state measurements of ^4He saturated vapor near the ?-<span class="hlt">point</span> using a Superconducting Cavity Stabilized Oscillator (SCSO) system. By operating the SCSO in a dual-mode phase-locked loop configuration we will be able to measure the dielectric constant of ^4He to parts in 10^15 <span class="hlt">precision</span> and comparable accuracy. The dielectric constant in turn implies a value of the density to parts in 10^10. Other measured parameters include the temperature to sub-nK <span class="hlt">precision</span> using paramagnetic salt high-resolution thermometry (HRT) and pressure to parts in 10^9 using a Straty-Adams type diaphragm gauge. These substantially improved resolutions relative to existing data are expected to provide new insights into the interactions of helium atoms near Bose-Einstein condensation. Numerous error reduction techniques will be discussed, along with other applications of SCSO to <span class="hlt">precision</span> metrology.</p> <div class="credits"> <p class="dwt_author">Corcovilos, T. A.; Strayer, D. M.; Asplund, N. N.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">193</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4013112"> <span id="translatedtitle">The double-helix <span class="hlt">point</span> spread function enables <span class="hlt">precise</span> and accurate measurement of 3D single-molecule localization and orientation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Single-molecule-based super-resolution fluorescence microscopy has recently been developed to surpass the diffraction limit by roughly an order of magnitude. These methods depend on the ability to <span class="hlt">precisely</span> and accurately measure the <span class="hlt">position</span> of a single-molecule emitter, typically by fitting its emission pattern to a symmetric estimator (e.g. centroid or 2D Gaussian). However, single-molecule emission patterns are not isotropic, and depend highly on the orientation of the molecule’s transition dipole moment, as well as its z-<span class="hlt">position</span>. Failure to account for this fact can result in localization errors on the order of tens of nm for in-focus images, and ~50–200 nm for molecules at modest defocus. The latter range becomes especially important for three-dimensional (3D) single-molecule super-resolution techniques, which typically employ depths-of-field of up to ~2 ?m. To address this issue we report the simultaneous measurement of <span class="hlt">precise</span> and accurate 3D single-molecule <span class="hlt">position</span> and 3D dipole orientation using the Double-Helix <span class="hlt">Point</span> Spread Function (DH-PSF) microscope. We are thus able to significantly improve dipole-induced <span class="hlt">position</span> errors, reducing standard deviations in lateral localization from ~2x worse than photon-limited <span class="hlt">precision</span> (48 nm vs. 25 nm) to within 5 nm of photon-limited <span class="hlt">precision</span>. Furthermore, by averaging many estimations of orientation we are able to improve from a lateral standard deviation of 116 nm (~4x worse than the <span class="hlt">precision</span>, 28 nm) to 34 nm (within 6 nm).</p> <div class="credits"> <p class="dwt_author">Backlund, Mikael P.; Lew, Matthew D.; Backer, Adam S.; Sahl, Steffen J.; Grover, Ginni; Agrawal, Anurag; Piestun, Rafael; Moerner, W. E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">194</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1994BGeod..69....1J"> <span id="translatedtitle">Airborne vector gravimetry using <span class="hlt">precise</span>, <span class="hlt">position</span>-aided inertial measurement units</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Vector gravimetry using a <span class="hlt">precise</span> inertial navigation system continually updated with external <span class="hlt">position</span> data, for example using GPS, is studied with respect to two problems. The first concerns the attitude accuracy requirement for horizontal gravity component estimation. With covariance analyses in the space and frequency domains it is argued that with relatively stable uncompensated gyro drift, the short-wavelength gravity vector can be estimated without the aid of external attitude updates. The second problem concerns the state-space estimation of the gravity signal where considerable approximations must be assumed in the gravity model in order to take advantage of the ensemble error estimation afforded by the Kalman filter technique. Gauss-Markov models for the gravity field are specially designed to reflect the attenuation of the signal at a specific altitude and the omission of the long-wavelength components from the estimation. With medium accuracy INS/GPS systems, the horizontal components of gravity with wavelengths shorter than 250 km should be estimable to an accuracy of 4-6 mgal (µg); while high accuracy systems should yield an improvement to 1-2 mgal.</p> <div class="credits"> <p class="dwt_author">Jekeli, Christopher</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">195</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/19160076"> <span id="translatedtitle">A new <span class="hlt">positive</span>/negative selection scheme for <span class="hlt">precise</span> BAC recombineering.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Recombineering technology allows the modification of large DNA constructs without using restriction enzymes, enabling the use of bacterial artificial chromosomes (BACs) in genetic engineering of animals and plants as well as in the studies of structures and functions of chromosomal elements in DNA replication and transcription. Here, we report a new selection scheme of BAC recombineering. A dual kanamycin and streptomycin selection marker was constructed using the kanamycin resistance gene and bacterial rpsL (+) gene. Recombination cassettes generated using this dual marker was used to make <span class="hlt">precise</span> modifications in BAC constructs in a two-step procedure without leaving behind any unwanted sequences. The dual marker was first inserted into the site of modifications by <span class="hlt">positive</span> selection of kanamycin resistance. In the second step, the counter-selection of streptomycin sensitivity resulted in the replacement of the dual marker with intended modified sequences. This method of BAC modification worked as efficiently as the previously reported galK method and provided a faster and more cost-effective alternative to the galK method. PMID:19160076</p> <div class="credits"> <p class="dwt_author">Wang, Shuwen; Zhao, Yuanjun; Leiby, Melanie; Zhu, Jiyue</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">196</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.G13B0944C"> <span id="translatedtitle"><span class="hlt">Precise</span> Gravity Measurements for Lunar Laser Ranging at Apache <span class="hlt">Point</span> Observatory</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Lunar Laser Ranging (LLR) at Apache <span class="hlt">Point</span> Observatory began in 2006 under the APOLLO project using a 3.5 m telescope on a 2780 m summit in New Mexico. Recent improvements in the technical operations are producing uncertainties at the few-mm level in the 1.5 x 10^13 cm separation of the solar orbits of the Earth and Moon. This level of sensitivity permits a number of important aspects of gravitational theory to be tested. Among these is the Equivalence Principle that determines the universality of free fall, tests of the time variation of the Gravitational Constant G, deviations from the inverse square law, and preferred frame effects. In 2009 APOLLO installed a superconducting gravimeter (SG) on the concrete pier under the main telescope to further constrain the deformation of the site as part of an initiative to improve all aspects of the modeling process. We have analyzed more than 3 years of high quality SG data that provides unmatched accuracy in determining the local tidal gravimetric factors for the solid Earth and ocean tide loading. With on-site gravity we have direct measurements of signals such as polar motion, and can compute global atmospheric and hydrological loading for the site using GLDAS and local hydrology models that are compared with the SG observations. We also compare the SG residuals with satellite estimates of seasonal ground gravity variations from the GRACE mission. Apache <span class="hlt">Point</span> is visited regularly by a team from the National Geospatial-Intelligence Agency to provide absolute gravity values for the calibration of the SG and to determine secular gravity changes. Nearby GPS location P027 provides continuous <span class="hlt">position</span> information from the Plate Boundary Observatory of Earthscope that is used to correlate gravity/height variations at the site. Unusual aspects of the data processing include corrections for the telescope azimuth that appear as small offsets at the 1 ?Gal level and can be removed by correlating the azimuth data with the SG residuals.</p> <div class="credits"> <p class="dwt_author">Crossley, D. J.; Murphy, T.; Boy, J.; De Linage, C.; Wheeler, R. D.; Krauterbluth, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">197</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008SPIE.7145E..94P"> <span id="translatedtitle">Accuracy analysis on C/A code and P(Y) code pseudo-range of GPS dual frequency receiver and application in <span class="hlt">point</span> <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">When the Anti-Spoofing (A-S) is active, the civilian users have some difficulties in using the P(Y) code for <span class="hlt">precise</span> navigation and <span class="hlt">positioning</span>. Z-tracking technique is one of the effective methods to acquire the P(Y) code. In this paper, the accuracy of pseudoranges from C/A code and P(Y) code for dual frequency GPS receiver is discussed. The principle of measuring the encrypted P(Y) code is described firstly, then a large data set from IGS tracking stations is utilized for analysis and verification with the help of a <span class="hlt">precise</span> <span class="hlt">point</span> <span class="hlt">positioning</span> software developed by authors. Especially, P(Y) code pseudoranges of civilian GPS receivers allow eliminating/reducing the effect of ionospheric delay and improve the <span class="hlt">precision</span> of <span class="hlt">positioning</span>. The <span class="hlt">point</span> <span class="hlt">positioning</span> experiments for this are made in the end.</p> <div class="credits"> <p class="dwt_author">Peng, Xiuying; Fan, Shijie; Guo, Jiming</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">198</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3871121"> <span id="translatedtitle">A Kalman Filter Implementation for <span class="hlt">Precision</span> Improvement in Low-Cost GPS <span class="hlt">Positioning</span> of Tractors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Low-cost GPS receivers provide geodetic <span class="hlt">positioning</span> information using the NMEA protocol, usually with eight digits for latitude and nine digits for longitude. When these geodetic coordinates are converted into Cartesian coordinates, the <span class="hlt">positions</span> fit in a quantization grid of some decimeters in size, the dimensions of which vary depending on the <span class="hlt">point</span> of the terrestrial surface. The aim of this study is to reduce the quantization errors of some low-cost GPS receivers by using a Kalman filter. Kinematic tractor model equations were employed to particularize the filter, which was tuned by applying Monte Carlo techniques to eighteen straight trajectories, to select the covariance matrices that produced the lowest Root Mean Square Error in these trajectories. Filter performance was tested by using straight tractor paths, which were either simulated or real trajectories acquired by a GPS receiver. The results show that the filter can reduce the quantization error in distance by around 43%. Moreover, it reduces the standard deviation of the heading by 75%. Data suggest that the proposed filter can satisfactorily preprocess the low-cost GPS receiver data when used in an assistance guidance GPS system for tractors. It could also be useful to smooth tractor GPS trajectories that are sharpened when the tractor moves over rough terrain.</p> <div class="credits"> <p class="dwt_author">Gomez-Gil, Jaime; Ruiz-Gonzalez, Ruben; Alonso-Garcia, Sergio; Gomez-Gil, Francisco Javier</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">199</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50759275"> <span id="translatedtitle">Neural-tuned PID controller for <span class="hlt">Point-to-point</span> (PTP) <span class="hlt">positioning</span> system: Model reference approach</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Point-to-point</span> (PTP) motion control systems play an important role in industrial engineering applications such as advanced manufacturing systems, semiconductor manufacturing systems and robot systems. Until know, PID (proportional-integral-derivative) controllers are still the most popular controller used in industrial control systems including PTP motion control systems due to their simplicity and also satisfactory performances. However, since the PID controller is developed</p> <div class="credits"> <p class="dwt_author">Wali Ahmad; M. M. Htut</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">200</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/4770096"> <span id="translatedtitle">FPC: A High-Speed Compressor for Double-<span class="hlt">Precision</span> Floating-<span class="hlt">Point</span> Data</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Many scientific programs exchange large quantities of double-<span class="hlt">precision</span> data between processing nodes and with mass storage devices. Data compression can reduce the number of bytes that need to be transferred and stored. However, data compression is only likely to be employed in high-end computing environments if it does not impede the throughput. This paper describes and evaluates FPC, a fast</p> <div class="credits"> <p class="dwt_author">Martin Burtscher; Paruj Ratanaworabhan</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_9");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return 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title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">201</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1989guco.proc..325G"> <span id="translatedtitle"><span class="hlt">Precision</span> <span class="hlt">pointing</span> and inertial line-of-sight stabilization using fine-steering mirror, and strap-down inertial sensors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In many space-based <span class="hlt">pointing</span> and tracking applications, the <span class="hlt">pointing</span> system must be stabilized using inertial references and the optical feedback signal is either unavailable or too low bandwidth, due to uncooperative targets or background clutter, to provide <span class="hlt">position</span> reference to the <span class="hlt">pointing</span> system. This paper presents results of the analyses and simulations for a <span class="hlt">pointing</span> system configuration based on the body-fixed telescope concept to show that microradian-<span class="hlt">pointing</span>, jitter system can be designed using inertial references from star trackers, accelerometers, and gyros for directed-energy weapons, surveillance, optical seekers, and laser communication.</p> <div class="credits"> <p class="dwt_author">Gupta, Avanindra A.; Germann, Lawrence M.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">202</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/21405320"> <span id="translatedtitle">Measurement of the <span class="hlt">positive</span> muon lifetime and determination of the Fermi constant to part-per-million <span class="hlt">precision</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We report a measurement of the <span class="hlt">positive</span> muon lifetime to a <span class="hlt">precision</span> of 1.0 ppm; it is the most <span class="hlt">precise</span> particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2×10(12) decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give ?(?(+)) (MuLan)=2?196?980.3(2.2)??ps, more than 15 times as <span class="hlt">precise</span> as any previous experiment. The muon lifetime gives the most <span class="hlt">precise</span> value for the Fermi constant: G(F) (MuLan)=1.166?378?8(7)×10(-5)??GeV(-2) (0.6 ppm). It is also used to extract the ?(-)p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling g(P). PMID:21405320</p> <div class="credits"> <p class="dwt_author">Webber, D M; Tishchenko, V; Peng, Q; Battu, S; Carey, R M; Chitwood, D B; Crnkovic, J; Debevec, P T; Dhamija, S; Earle, W; Gafarov, A; Giovanetti, K; Gorringe, T P; Gray, F E; Hartwig, Z; Hertzog, D W; Johnson, B; Kammel, P; Kiburg, B; Kizilgul, S; Kunkle, J; Lauss, B; Logashenko, I; Lynch, K R; McNabb, R; Miller, J P; Mulhauser, F; Onderwater, C J G; Phillips, J; Rath, S; Roberts, B L; Winter, P; Wolfe, B</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-28</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">203</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21532259"> <span id="translatedtitle">Measurement of the <span class="hlt">Positive</span> Muon Lifetime and Determination of the Fermi Constant to Part-per-Million <span class="hlt">Precision</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We report a measurement of the <span class="hlt">positive</span> muon lifetime to a <span class="hlt">precision</span> of 1.0 ppm; it is the most <span class="hlt">precise</span> particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2x10{sup 12} decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give {tau}{sub {mu}}{sup +}(MuLan)=2 196 980.3(2.2) ps, more than 15 times as <span class="hlt">precise</span> as any previous experiment. The muon lifetime gives the most <span class="hlt">precise</span> value for the Fermi constant: G{sub F}(MuLan)=1.166 378 8(7)x10{sup -5} GeV{sup -2} (0.6 ppm). It is also used to extract the {mu}{sup -}p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling g{sub P}.</p> <div class="credits"> <p class="dwt_author">Webber, D. M.; Chitwood, D. B.; Crnkovic, J.; Debevec, P. T.; Hertzog, D. W.; Kammel, P.; Kiburg, B.; Kizilgul, S.; Kunkle, J.; McNabb, R.; Winter, P.; Wolfe, B. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Tishchenko, V.; Battu, S.; Dhamija, S.; Gorringe, T. P.; Rath, S. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States); Peng, Q.; Carey, R. M.; Earle, W. [Department of Physics, Boston University, Boston, Massachusetts 02215 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-28</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">204</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890018511&hterms=parabolic+reflectors+levy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dparabolic%2Breflectors%2Blevy"> <span id="translatedtitle"><span class="hlt">Precision</span> <span class="hlt">pointing</span> compensation for DSN antennas with optical distance measuring sensors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The <span class="hlt">pointing</span> control loops of Deep Space Network (DSN) antennas do not account for unmodeled deflections of the primary and secondary reflectors. As a result, structural distortions due to unpredictable environmental loads can result in uncompensated boresight shifts which degrade <span class="hlt">pointing</span> accuracy. The design proposed here can provide real-time bias commands to the <span class="hlt">pointing</span> control system to compensate for environmental effects on <span class="hlt">pointing</span> performance. The bias commands can be computed in real time from optically measured deflections at a number of <span class="hlt">points</span> on the primary and secondary reflectors. Computer simulations with a reduced-order finite-element model of a DSN antenna validate the concept and lead to a proposed design by which a ten-to-one reduction in <span class="hlt">pointing</span> uncertainty can be achieved under nominal uncertainty conditions.</p> <div class="credits"> <p class="dwt_author">Scheid, R. E.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">205</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA385449"> <span id="translatedtitle">Real Time, Autonomous, <span class="hlt">Precise</span> Orbit Determination Using the Global <span class="hlt">Positioning</span> System.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">In an effort to estimate <span class="hlt">precise</span> satellite ephemeris in real-time on board a satellite, the Goddard Space Flight Center (GSFC) created the GPS enhanced Orbit Determination Experiment (GEODE) flight navigation software. This dissertation offers alternative...</p> <div class="credits"> <p class="dwt_author">D. B. Goldstein</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">206</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/19579736"> <span id="translatedtitle">Multilateration with the Wide-Angle Airborne Laser Ranging System: <span class="hlt">Positioning</span> <span class="hlt">Precision</span> and Atmospheric Effects</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Numerical simulations based on previously validated models for the wide-angle airborne laser ranging system are used here for assessing the <span class="hlt">precision</span> in coordinate estimates of ground-based cube-corner retroreflectors (CCR s). It is shown that the <span class="hlt">precision</span> can be optimized to first order as a function of instrument performance, number of laser shots (LS s), and network size. Laser beam divergence,</p> <div class="credits"> <p class="dwt_author">Olivier Bock</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">207</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890018512&hterms=workers+compensation&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dworkers%2Bcompensation"> <span id="translatedtitle">The effects of atmospheric turbulence on <span class="hlt">precision</span> optical measurements used for antenna-<span class="hlt">pointing</span> compensation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Blind <span class="hlt">pointing</span> of the Deep Space Network (DSN) 70-meter antennas can be improved if distortions of the antenna structure caused by unpredictable environmental loads can be measured in real-time, and the resulting boresight shifts evaluated and incorporated into the <span class="hlt">pointing</span> control loops. The measurement configuration of a proposed <span class="hlt">pointing</span> compensation system includes an optical range sensor that measures distances to selected <span class="hlt">points</span> on the antenna surface. The effect of atmospheric turbulence on the accuracy of optical distance measurements and a method to make in-situ determinations of turbulence-induced measurement errors are discussed.</p> <div class="credits"> <p class="dwt_author">Nerheim, N.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">208</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20060041208&hterms=positioning&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3D%2522positioning%2522"> <span id="translatedtitle"><span class="hlt">Precise</span> GPS/Acoustic <span class="hlt">Positioning</span> of Seafloor Reference <span class="hlt">Points</span> for Tectonic Studies</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Global networks for crustal strain measurement provide important constraints for studies of tectonic plate motion and deformation. To date, crustal strain measurements have been possible only in terrestrial settings: on continental plates and island sites within oceanic plates.</p> <div class="credits"> <p class="dwt_author">Spiess, F. N.; Chadwell, C.; Hildebrand, J. A.; Young, L. E.; Purcell, G. H., Jr.; Dragert, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">209</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/19274863"> <span id="translatedtitle">Application of the nonlinear, double-dynamic taguchi method to the <span class="hlt">precision</span> <span class="hlt">positioning</span> device using combined piezo-vcm actuator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In this research, the nonlinear, double-dynamic Taguchi method was used as design and analysis methods for a high-<span class="hlt">precision</span> <span class="hlt">positioning</span> device using the combined piezo-voice-coil motor (VCM) actuator. An experimental investigation into the effects of two input signals and three control factors were carried out to determine the optimum parametric configuration of the <span class="hlt">positioning</span> device. The double-dynamic Taguchi method, which permits</p> <div class="credits"> <p class="dwt_author">Yung-Tien Liu; Rong-Fong Fung; Chun-Chao Wang</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">210</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50883890"> <span id="translatedtitle">3D <span class="hlt">point</span> clouds processing and <span class="hlt">precise</span> surface reconstruction of the face</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Sinusoidal fringe is projected to the face by a double fringe 3D scanner, and it is modulated by the face profile. Two separated <span class="hlt">point</span> clouds of the face are obtained by the conversion of fringe image with demodulation and unwrapping processing. The system is calibrated by the calibration block. Automatic registration of two <span class="hlt">point</span> clouds of the face is conducted</p> <div class="credits"> <p class="dwt_author">Meng Fanwen; Wu Lushen; Luo Liping</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">211</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53067749"> <span id="translatedtitle">LDPC decoder with a limited-<span class="hlt">precision</span> FPGA-based floating-<span class="hlt">point</span> multiplication coprocessor</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Implementing the sum-product algorithm, in an FPGA with an embedded processor, invites us to consider a tradeoff between computational <span class="hlt">precision</span> and computational speed. The algorithm, known outside of the signal processing community as Pearl's belief propagation, is used for iterative soft-decision decoding of LDPC codes. We determined the feasibility of a coprocessor that will perform product computations. Our FPGA-based coprocessor</p> <div class="credits"> <p class="dwt_author">Raymond Moberly; Michael O'Sullivan; Khurram Waheed</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">212</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/3427576"> <span id="translatedtitle">Multiple <span class="hlt">positive</span> fixed <span class="hlt">points</span> of nonlinear operators on ordered Banach spaces</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The existence of multiple <span class="hlt">positive</span> fixed <span class="hlt">points</span> of completely continuous nonlinear operators defined on the cone of an ordered Banach space is considered. The main results give sufficient conditions for such an operator to have two, and in some cases three, <span class="hlt">positive</span> fixed <span class="hlt">points</span>. (RWR)</p> <div class="credits"> <p class="dwt_author">R. W. Leggett; L. R. Williams</p> <p class="dwt_publisher"></p> <p class="publishDate">1979-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">213</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50295665"> <span id="translatedtitle">Dynamic <span class="hlt">positioning</span> and way-<span class="hlt">point</span> tracking of underactuated AUVs in the presence of ocean currents</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper addresses the problem of dynamic <span class="hlt">positioning</span> and way-<span class="hlt">point</span> tracking of underactuated autonomous underwater vehicles (AUVs) in the presence of constant unknown ocean currents and parametric model uncertainty. A nonlinear adaptive controller is proposed that steers an AUV so as to track a sequence of <span class="hlt">points</span> consisting of desired <span class="hlt">positions</span> (x, y) in an inertial reference frame, followed by</p> <div class="credits"> <p class="dwt_author">A. P. Aguiar; A. M. Pascoal</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">214</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24735503"> <span id="translatedtitle">The effect of patient <span class="hlt">positioning</span> on the <span class="hlt">precision</span> of model-based radiostereometric analysis.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">A repeatable method for in vivo and in vitro measurement of polyethylene wear in total knee replacement (TKA) is needed. This research examines the model-based radiostereometric analysis' (MBRSA) in vitro <span class="hlt">precision</span> under different patient-radiograph orientations and flexion angles of the knee using a TKA phantom. Anterior-posterior and medial-lateral imaging orientations showed the highest <span class="hlt">precision</span>; better than 0.036mm (3-dimensional translation) and 0.089° (3-dimensional rotation). Flexion of the knee did not affect MBRSA <span class="hlt">precision</span>. Medial-lateral imaging is advantageous as it allows for flexion of the knee joint during an RSA examination, thus providing greater information for wear measurement. PMID:24735503</p> <div class="credits"> <p class="dwt_author">Gascoyne, Trevor C; Morrison, Jason B; Turgeon, Thomas R</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">215</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ias.ac.in/sadhana/Pdf2004Apr/Pe1162.pdf"> <span id="translatedtitle"><span class="hlt">Precision</span> <span class="hlt">pointing</span> of imaging spacecraft using gyro-based attitude reference with horizon sensor updates</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Remote sensing satellites are required to meet stringent <span class="hlt">pointing</span> and drift rate requirements for imaging operations. For\\u000a achieving these <span class="hlt">pointing</span> and stability requirements, continuous and accurate three-axis attitude information is required.\\u000a Inertial sensors like gyros provide continuous attitude information with better short-term stability and less random errors.\\u000a However, gyro measurements are affected by drifts. Hence over time, attitudes based on</p> <div class="credits"> <p class="dwt_author">N. Venkateswaran; P. S. Goel; M. S. Siva; P. Natarajan; E. Krishnakumar; N. K. Philip</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">216</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1280741"> <span id="translatedtitle">A methodology for evaluating the <span class="hlt">precision</span> of fixed-<span class="hlt">point</span> systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The minimization of cost, power consumption and time-to-market of DSP applications requires the development of methodologies for the automatic implementation of floating-<span class="hlt">point</span> algorithms in fixed-<span class="hlt">point</span> architectures. In this paper, a new methodology for evaluating the quality of an implementation through the automatic determination of the Signal to Quantization Noise Ratio (SQNR) is presented. The modelization of the system at the</p> <div class="credits"> <p class="dwt_author">Daniel Menard; Olivier Sentieys</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">217</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/4711379"> <span id="translatedtitle">Double <span class="hlt">Precision</span> Hybrid-Mode Floating-<span class="hlt">Point</span> FPGA CORDIC Coprocessor</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">FPGA chips have become a promising option for accelerating scientific applications, which involve many floating-<span class="hlt">point</span> transcendental functions, such as sin, log, exp, sqrt and etc. In this paper, we present a 64-bit ANSI\\/IEEE floating-<span class="hlt">point</span> CORDIC co-processor on FPGA, providing all known CORDIC functions. And there is no 64-bit CORDIC implementation on FPGA known to us. We propose a hybrid-mode CORDIC</p> <div class="credits"> <p class="dwt_author">Jie Zhou; Yong Dou; Yuanwu Lei; Jinbo Xu; Yazhuo Dong</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">218</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://users.isr.ist.utl.pt/~pedro/publications/cdc2002auvtrack.pdf"> <span id="translatedtitle">Dynamic <span class="hlt">positioning</span> and way-<span class="hlt">point</span> tracking of underactuated AUVs in the presence of ocean currents</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper addresses the problem of dynamic <span class="hlt">positioning</span> and way-<span class="hlt">point</span> tracking of underactuated autonomous underwater vehicles (AUVs) in the presence of constant unknown ocean currents and parametric modelling uncertainty. A non-linear adaptive controller is proposed that steers an AUV along a sequence of way-<span class="hlt">points</span> consisting of desired <span class="hlt">positions</span> (x, y) in a inertial reference frame, followed by vehicle <span class="hlt">positioning</span> at</p> <div class="credits"> <p class="dwt_author">A. PEDRO AGUIAR; A. M. Pascoal</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">219</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27059572"> <span id="translatedtitle">Sensorless Maximum Power <span class="hlt">Point</span> Tracking of Wind by DFIG Using Rotor <span class="hlt">Position</span> Phase Lock Loop (PLL)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper presents an invention, the rotor <span class="hlt">position</span> phase lock loop (PLL), which enables maximum power <span class="hlt">point</span> (MPPT) tracking of wind by doubly-fed induction generators without needing a tachometer, an absolute <span class="hlt">position</span> encoder, or an anemometer. The rotor <span class="hlt">position</span> PLL is parameter variation insensitive, requiring only an estimate of the magnetization inductance for it to operate. It is also insensitive</p> <div class="credits"> <p class="dwt_author">Baike Shen; Bakari Mwinyiwiwa; Yongzheng Zhang; Boon-Teck Ooi</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">220</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.nt.ntnu.no/users/skoge/prost/proceedings/ifac2005/Fullpapers/02338.pdf"> <span id="translatedtitle"><span class="hlt">Precise</span> <span class="hlt">positioning</span> of piezo-actuated stages using hysteresis-observer based control</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The piezo-actuated stages are composed of the piezoelectric actuator and the <span class="hlt">positioning</span> mechanism. The <span class="hlt">positioning</span> accuracy of the piezo-actuated stage is limited due to hysteretic nonlinearity of the PEA and friction behaviour of the <span class="hlt">positioning</span> mechanism. To compensate this nonlinearity of piezoelectric actuator, a PI feedback control associated with feedforward compensating based on the hysteresis observer is proposed in this</p> <div class="credits"> <p class="dwt_author">Chih-Jer Lin; Sheng-Ren Yang</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_10");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span 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</span> </span> <a id="NextPageLink" onclick='return showDiv("page_13");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">221</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/42033686"> <span id="translatedtitle">Measuring <span class="hlt">precise</span> sea level from a buoy using the global <span class="hlt">positioning</span> system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">High-accuracy sea surface <span class="hlt">positioning</span> is required for sea floor geodesy, satellite altimeter verification, and the study of sea level. An experiment to study the feasibility of using the Global <span class="hlt">Positioning</span> System (GPS) for accurate sea surface <span class="hlt">positioning</span> was conducted. A GPS-equipped buoy (floater) was deployed off the Scripps pier at La Jolla, California during December 13-15, 1989. Two reference GPS</p> <div class="credits"> <p class="dwt_author">Christian Rocken; Thomas M. Kelecy; George H. Born; Larry E. Young; George H. Purcell; Susan Kornreich Wolf</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">222</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gmat.unsw.edu.au/snap/publications/wang_etal2001c.pdf"> <span id="translatedtitle">Integration of GNSS and Pseudo-Satellites: New Concepts for <span class="hlt">Precise</span> <span class="hlt">Positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Current Global Navigation Satellite Systems (GNSS), such as the GPS and Glonass systems, have been widely used in surveying and geodesy. It is well known that for such spaceborne satellite <span class="hlt">positioning</span> systems the accuracy, availability and reliability of the <span class="hlt">positioning</span> results is very dependent on both the number and geometric distribution of satellites being tracked. However, under some harsh observing</p> <div class="credits"> <p class="dwt_author">J. Wang; C. Rizos; L. Dai; T. Tsujii; J. Barnes; D. Grejner-Brzezinska; C. K. Toth</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">223</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22291537"> <span id="translatedtitle">Sensor for high speed, high <span class="hlt">precision</span> measurement of 2-d <span class="hlt">positions</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">A sensor system to measure the 2-D <span class="hlt">position</span> of an object that intercepts a plane in space is presented in this paper. This sensor system was developed with the aim of measuring the height and lateral <span class="hlt">position</span> of contact wires supplying power to electric locomotives. The sensor comprises two line-scans focused on the zone to be measured and <span class="hlt">positioned</span> in such a way that their viewing planes are on the same plane. The report includes a mathematical model of the sensor system, and details the method used for calibrating the sensor system. The procedure used for high speed measurement of object <span class="hlt">position</span> in space is also described, where measurement acquisition time was less than 0.7 ms. Finally, <span class="hlt">position</span> measurement results verifying system performance in real time are given. PMID:22291537</p> <div class="credits"> <p class="dwt_author">Luna, Carlos A; Lázaro, José L; Mazo, Manuel; Cano, Angel</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">224</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19730001650&hterms=laser+triangulation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dlaser%2Btriangulation"> <span id="translatedtitle">Improvement of a geodetic triangulation through control <span class="hlt">points</span> established by means of satellite or <span class="hlt">precision</span> traversing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Whether any significant increment to accuracy could be transferred from a super-control continental net (continental satellite net or super-transcontinental traverse) to the fundamental geodetic net (first-order triangulation) is discussed. This objective was accomplished by evaluating the <span class="hlt">positional</span> accuracy improvement for a triangulation station, which is near the middle of the investigated geodetic triangulation net, by using various station constraints over its geodetic <span class="hlt">position</span>. This investigation on a 1858 kilometer long triangulation chain shows that the super-control net can provide a useful constraint to the investigated geodetic triangulation net, and thus can improve it only when the accuracy of super-control net is at least 1 part in 500,000.</p> <div class="credits"> <p class="dwt_author">Saxena, N. K.</p> <p class="dwt_publisher"></p> <p class="publishDate">1972-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">225</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=N8812477"> <span id="translatedtitle">GPS (Global <span class="hlt">Position</span> System) Vertical Axis Performance Enhancement for Helicopter <span class="hlt">Precision</span> Landing Approach.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">Several areas were investigated for improving vertical accuracy for a rotorcraft using the differential Global <span class="hlt">Positioning</span> System (GPS) during a landing approach. Continuous deltaranging was studied and the potential improvement achieved by estimating acc...</p> <div class="credits"> <p class="dwt_author">R. P. Denaro J. Beser</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">226</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/7878212"> <span id="translatedtitle">Patient <span class="hlt">positioning</span> for fractionated <span class="hlt">precision</span> radiation treatment of targets in the head using fiducial markers.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">When irradiating targets in the brain, an accurately localised dose is often needed. One crucial moment to achieve this is the <span class="hlt">positioning</span> of the patient. We have developed a <span class="hlt">positioning</span> method where the patient is immobilised with a bite block and a head mould, and where the <span class="hlt">position</span> of the target is determined by X-ray imaging of fiducial markers that are placed in the patient's skull. A method for computing the transformation needed to move the target from the observed to the prescribed <span class="hlt">position</span> and orientation is described. This method uses the information from two orthogonal X-ray images and takes measurement errors and data from three or more markers into account. Results from using the method clinically in proton beam therapy are given. PMID:7878212</p> <div class="credits"> <p class="dwt_author">Grusell, E; Montelius, A; Russell, K R; Blomquist, E; Pellettieri, L; Lilja, A; Moström, U; Jakobsson, P</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">227</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013QuEle..43.1159M"> <span id="translatedtitle">High-<span class="hlt">precision</span> method for determining the <span class="hlt">position</span> of laser beam focal plane</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The method of wavefront doubled-frequency spherical modulation for determining the laser beam waist <span class="hlt">position</span> has been simulated and experimentally studied. The error in determining the focal plane <span class="hlt">position</span> is less than 10-5 D. The amplitude of the control doubled-frequency electric signal is experimentally found to correspond to 12% of the total radiation power. Reported at the 'Laser Optics' Conference (St. Petersburg, Russia, June 2012).</p> <div class="credits"> <p class="dwt_author">Malashko, Ya I.; Kleimenov, A. N.; Potemkin, I. B.; Khabibulin, V. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">228</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020011676&hterms=size+universe&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsize%2Buniverse"> <span id="translatedtitle">Measurement of <span class="hlt">Precision</span> Geometric Distances to Three Anchor <span class="hlt">Points</span> in the Local Universe</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We proposed a program to measure distances directly with accuracies of 5% to three anchor <span class="hlt">points</span> in the Local Universe. We planned to accomplish this by conducting Very Long Baseline Interferometry (VLBI) observations of NGC 4258, M 33, and Sgr A*. These distance estimates should have a minimum of systematic uncertainty and can be used to re-calibrate several 'standard candles,' such as Cepheid and RR Lyrae variables. This will place the Galactic and extragalactic distance scales on much firmer ground. The primary contribution of our program will be to provide crucial independent checks and calibrations of extragalactic distance measurements. This will contribute to the ultimate success and impact of the HST Key Project on Extragalactic Distances and the Full-Sky Astrometric Mapping Explorer (FAME). Additionally, since distances are fundamental to astrophysics, our results will affect a large number of general projects on NASA facilities such as the Hubble Space Telescope, Chandra X-ray Observatory, and Next Generation Space Telescope.</p> <div class="credits"> <p class="dwt_author">Reid, Mark J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">229</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920007593&hterms=WO3&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DWO3"> <span id="translatedtitle">Apparatus for <span class="hlt">precision</span> focussing and <span class="hlt">positioning</span> of a beam waist on a target</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The invention relates to optical focussing apparatus and, more particularly, to optical apparatus for focussing a highly collimated Gaussian beam which provides independent and fine control over the focus waist diameter, the focus <span class="hlt">position</span> both along the beam axis and transverse to the beam, and the focus angle. A beam focussing and <span class="hlt">positioning</span> apparatus provides focussing and <span class="hlt">positioning</span> for the waist of a waisted beam at a desired location on a target such as an optical fiber. The apparatus includes a first lens, having a focal plane f sub 1, disposed in the path of an incoming beam and a second lens, having a focal plane f sub 2 and being spaced downstream from the first lens by a distance at least equal to f sub 1 + 10 f sub 2, which cooperates with the first lens to focus the waist of the beam on the target. A rotatable optical device, disposed upstream of the first lens, adjusts the angular orientation of the beam waist. The transverse <span class="hlt">position</span> of the first lens relative to the axis of the beam is varied to control the transverse <span class="hlt">position</span> of the beam waist relative to the target (a fiber optic as shown) while the relative axial <span class="hlt">positions</span> of the lenses are varied to control the diameter of the beam waist and to control the axial <span class="hlt">position</span> of the beam waist. Mechanical controllers C sub 1, C sub 2, C sub 3, C sub 4, and C sub 5 control the elements of the optical system. How seven adjustments can be made to correctly couple a laser beam into an optical fiber is illustrated. Prior art systems employing optical techniques to couple a laser beam into an optical fiber or other target simply do not provide the seven necessary adjustments. The closest known prior art, a Newport coupler, provides only two of the seven required adjustments.</p> <div class="credits"> <p class="dwt_author">Lynch, Dana H. (inventor); Gunter, William D. (inventor); Mcalister, Kenneth W. (inventor)</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">230</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AdSpR..49.1088S"> <span id="translatedtitle">Towards accurate atmospheric mass density determination Using <span class="hlt">precise</span> <span class="hlt">positional</span> information of space objects</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This paper presents a new method of deriving atmospheric mass densities with a high temporal resolution from <span class="hlt">precise</span> orbit data of low earth orbiting (LEO) space objects. This method is based on the drag perturbation equation of the semi-major axis of the orbit of LEO space objects which relates the change rate of the semi-major axis to the atmospheric mass density. The effectiveness of the new method is evaluated using the GFZ-ISDC GPS rapid science orbit (RSO) products of the CHAMP satellite over a time period of 3 months. The densities derived using this new method and obtained from accelerometer data are compared and good agreements are achieved. An example of using the derived density to generate good orbit prediction for CHAMP is presented.</p> <div class="credits"> <p class="dwt_author">Sang, J.; Smith, C.; Zhang, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">231</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5598882"> <span id="translatedtitle">Measuring <span class="hlt">precise</span> sea level from a buoy using the global <span class="hlt">positioning</span> system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">High-accuracy sea surface <span class="hlt">positioning</span> is required for sea floor geodesy, satellite altimeter verification, and the study of sea level. An experiment to study the feasibility of using the Global <span class="hlt">Positioning</span> System (GPS) for accurate sea surface <span class="hlt">positioning</span> was conducted. A GPS-equipped buoy (floater) was deployed off the Scripps pier at La Jolla, California during December 13-15, 1989. Two reference GPS receivers were placed on land, one within {approximately}100 m of the floater, and the other about 80 km inland at the laser ranging site on Monument Peak. The <span class="hlt">position</span> of the floater was determined relative to the land-fixed receivers using: (a) kinematic GPS processing software developed at the National Geodetic Survey (NGS), and (b) the Jet Propulsion Laboratory's GIPSY (GPS Inferred <span class="hlt">Positioning</span> SYstem) software. Sea level and ocean wave spectra were calculated from GPPS measurements. These results were compared to measurements made with a NOAA tide gauge and a Paros{trademark} pressure transducer (PPT). GPS sea level for the short 100-m baseline agrees with the PPT sea level at the 1-cm level and has an rms variation of 5 mm over a period of 4 hours. Agreement between results with the two independent GPS analyses is on the order of a few millimeters. Processing of the longer Monument Peak - floater baseline is in progress and will require orbit adjustments and tropospheric modeling to obtain results comparable to the short baseline.</p> <div class="credits"> <p class="dwt_author">Rocken, C.; Kelecy, T.M.; Born, G.H. (Univ. of Colorado, Boulder (USA)); Young, L.E.; Purcell, G.H. Jr.; Wolf, S.K. (California Inst. of Tech., Pasadena (USA))</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">232</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20030000577&hterms=size+universe&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsize%2Buniverse"> <span id="translatedtitle">Measurement of <span class="hlt">Precision</span> Geometric Distances to Three Anchor <span class="hlt">Points</span> in the Local Universe</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Our program, funded by a NASA/SARA 3-yr grant, is designed to measure distances directly with accuracies of 5% to three anchor <span class="hlt">points</span> in the Local Universe. We are attacking this problem on three fronts, using Very Long Baseline Interferometry (VLBI) observations of NGC 4258, M 33, and Sgr A*. We plan to provide distance estimates, with a minimum of systematic uncertainty, that can be used to re-calibrate several 'standard candles,' such as Cepheid and RR Lyrae variables. This will place the Galactic and extragalactic distance scales on much firmer ground. The program will provide crucial, independent checks and calibrations of extragalactic distance measurements, and will contribute to the ultimate success and impact of the HST Key Project on Extragalactic Distances, the Full-Sky Astrometric Mapping Explorer (FAME), and any future NASA astrometric missions. Additionally, since distances are fundamental to astrophysics, our results will affect a large number of general projects on NASA facilities such as the HST (Hubble Space Telescope), CXO (Chandra X-Ray Observatory), and NGST (Next Generation Space Telescope).</p> <div class="credits"> <p class="dwt_author">Reid, Mark J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">233</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19780017105&hterms=Data+type+match&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DData%2Btype%2Bmatch"> <span id="translatedtitle"><span class="hlt">Precision</span> <span class="hlt">Positional</span> Data of General Aviation Air Traffic in Terminal Air Space</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Three dimensional radar tracks of general aviation air traffic at three uncontrolled airports are considered. Contained are data which describe the <span class="hlt">position</span>-time histories, other derived parameters, and reference data for the approximately 1200 tracks. All information was correlated such that the date, time, flight number, and runway number match the pattern type, aircraft type, wind, visibility, and cloud conditions.</p> <div class="credits"> <p class="dwt_author">Melson, W. E., Jr.; Parker, L. C.; Northam, A. M.; Singh, R. P.</p> <p class="dwt_publisher"></p> <p class="publishDate">1978-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">234</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.nbmg.unr.edu/staff/pdfs/Vigue_92GL01575.pdf"> <span id="translatedtitle"><span class="hlt">Precise</span> determination of Earth's center of mass using measurements from the global <span class="hlt">positioning</span> system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Global <span class="hlt">Positioning</span> System (GPS) data from a worldwide geodetic experiment were collected during a 3 week period early in 1991. We estimated geocentric station coordinates using the GPS data, thus defining a dynamically determined reference frame origin which should coincide with the Earth center of mass, or geocenter. The 3-week GPS av- erage geocenter estimates agree to 7-13 cm with</p> <div class="credits"> <p class="dwt_author">Yvonne Vigue; Stephen M. Lichten; Geoffrey Blewitt; Michael B. Heflin; Rajendra P. Malla</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">235</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/526823"> <span id="translatedtitle"><span class="hlt">Position</span> and collision <span class="hlt">point</span> measurement system for Fermilab{close_quote}s interaction regions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A higher resolution beam <span class="hlt">position</span> monitor (BPM) system has been developed at FNAL to measure the transverse <span class="hlt">position</span> of the beam at opposite ends of the Collision Hall. A secondary function is to measure the longitudinal location of the collision <span class="hlt">point</span>. This system is called the Collision <span class="hlt">Point</span> Monitor (CPM). The transverse <span class="hlt">positions</span> are determined by software rectification and integration of a BPM signal obtained from a sampling oscilloscope. A difference over sum calculation of the A and B signals yields the <span class="hlt">position</span>. The longitudinal location is obtained by measuring the difference in time between the proton and antiproton bunches at both ends of the Collision Hall. The downstream difference is then subtracted from the upstream difference and the result is multiplied by half the speed of light to yield the collision <span class="hlt">point</span> error. {copyright} {ital 1997 American Institute of Physics.}</p> <div class="credits"> <p class="dwt_author">Olson, M.; Hahn, A.A. [Fermi National Accelerator Laboratory, Box 500, Batavia , Illinois 60510 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">236</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20060017049&hterms=helping+poor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhelping%2Bpoor"> <span id="translatedtitle">Dilution of <span class="hlt">Precision</span>-Based Lunar Navigation Assessment for Dynamic <span class="hlt">Position</span> Fixing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The NASA Vision for Space Exploration is focused on the return of astronauts to the Moon. While navigation systems have already been proven in the Apollo missions to the moon, the current exploration campaign will involve more extensive and extended missions requiring new concepts for lunar navigation. In contrast to Apollo missions, which were limited to the near-side equatorial region of the moon, missions under the Exploration Systems Initiative will require navigation on the moon's limb and far-side. As these regions have poor Earth visibility, a navigation system comprised solely of Earth-based tracking stations will not provide adequate navigation solutions in these areas. In this paper, a Dilution of <span class="hlt">Precision</span> (DoP) based analysis of the performance of a network of Moon orbiting satellites is provided. The analysis extends previous analysis of a Lunar Network (LN) of navigation satellites by providing an assessment of the capability associated with a variety of assumptions. These assumptions are with regard to the navigation receiver and satellite visibility. The assessment is accomplished by making appropriately formed estimates of DoP. Different adaptations of DoP (i.e., GDoP, PDoP, etc.) are associated with a different set of assumptions regarding augmentations to the navigation receiver or transceiver.</p> <div class="credits"> <p class="dwt_author">Sands, Obed S.; Connolly, Joseph W.; Welch, Bryan W.; Carpenter, James R.; Ely, Todd A.; Berry, Kevin</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">237</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/877442"> <span id="translatedtitle">High-<span class="hlt">Precision</span> Resonant Cavity Beam <span class="hlt">Position</span>, Emittance And Third-Moment Monitors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Linear colliders and FEL facilities need fast, nondestructive beam <span class="hlt">position</span> and profile monitors to facilitate machine tune-up, and for use with feedback control. FAR-TECH, Inc., in collaboration with SLAC, is developing a resonant cavity diagnostic to simultaneously measure the dipole, quadrupole and sextupole moments of the beam distribution. Measurements of dipole and quadrupole moments at multiple locations yield information about beam orbit and emittance. The sextupole moment can reveal information about beam asymmetry which is useful in diagnosing beam tail deflections caused by short-range dipole wakefields. In addition to the resonance enhancement of a single-cell cavity, use of a multi-cell standing-wave structure further enhances signal strength and improves the resolution of the device. An estimated resolution is better than 1 {micro}m in rms beam size and better than 1 nm in beam <span class="hlt">position</span>.</p> <div class="credits"> <p class="dwt_author">Barov, N.; Kim, J.S.; Weidemann, A.W.; /FARTECH, San Diego; Miller, R.H.; Nantista, C.D.; /SLAC</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-03-14</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">238</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27076701"> <span id="translatedtitle">Mutual Inductance of a <span class="hlt">Precise</span> Rogowski Coil in Dependence of the <span class="hlt">Position</span> of Primary Conductor</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Rogowski coil is a well-known current-to-voltage transducer. To use it for the high-accuracy measurement of AC current (at power supply frequency), all influencing quantities and their contribution should be recognized and analyzed. Thus, the partial influence due to the deviation from the central <span class="hlt">position</span> of the primary conductor for a real sensor, with the nonhomogeneous density of secondary turns,</p> <div class="credits"> <p class="dwt_author">Luka Ferkovic; Damir IliMember; Roman Malaric</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">239</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003ATel..205....1M"> <span id="translatedtitle"><span class="hlt">Precise</span> X-ray <span class="hlt">position</span> of A1744-36 (=XTE J1748-361?)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Ariel-5 X-ray transient A1744-36 and the newly-discovered transient XTE J1748-361 may be identical (ATEL #204). Based on a 16 ks Chandra ACIS-S observation of A1744-36 made on 2003 May 28, the <span class="hlt">position</span> of this source is RA(J2000) = 17:48:19.22, Dec(J2000) = -36:07:16.6 (uncertainty < 1").</p> <div class="credits"> <p class="dwt_author">McClintock, J.; Murray, S.; Garcia, M.; Jonker, P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">240</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26551209"> <span id="translatedtitle">Model reference adaptive control of air-lubricated capstan drive for <span class="hlt">precision</span> <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Because friction-induced nonlinearities in <span class="hlt">positioning</span> systems are generally range of motion-dependent, dual-model or dual-stage strategies are often adopted to deal with the inconsistencies encountered when a system moves from submicrometer steps (micro mode) to larger scale strokes (macro mode). Although good performance is usually obtained when each model\\/stage operates in its designed range of motion, a system frequently performs less</p> <div class="credits"> <p class="dwt_author">C. L Chao; J Neou</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_11");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">241</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JGeod.tmp...25P"> <span id="translatedtitle"><span class="hlt">Precise</span> station <span class="hlt">positions</span> from VLBI observations to satellites: a simulation study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Very long baseline interferometry (VLBI) tracking of satellites is a topic of increasing interest for the establishment of space ties. This shall strengthen the connection of the various space geodetic techniques that contribute to the International Terrestrial Reference Frame. The concept of observing near-Earth satellites demands research on possible observing strategies. In this paper, we introduce this concept and discuss its possible benefits for improving future realizations of the International Terrestrial Reference System. Using simulated observations, we develop possible observing strategies that allow the determination of radio telescope <span class="hlt">positions</span> in the satellite system on Earth with accuracies of a few millimeters up to 1-2 cm for weekly station coordinates. This is shown for satellites with orbital heights between 2,000 and 6,000 km, observed by dense regional as well as by global VLBI-networks. The number of observations, as mainly determined by the satellite orbit and the observation interval, is identified as the most critical parameter that affects the expected accuracies. For observations of global <span class="hlt">positioning</span> system satellites, we propose the combination with classical VLBI to radio sources or a multi-satellite strategy. Both approaches allow station <span class="hlt">position</span> repeatabilities of a few millimeters for weekly solutions.</p> <div class="credits"> <p class="dwt_author">Plank, Lucia; Böhm, Johannes; Schuh, Harald</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">242</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JGeod..88..659P"> <span id="translatedtitle"><span class="hlt">Precise</span> station <span class="hlt">positions</span> from VLBI observations to satellites: a simulation study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Very long baseline interferometry (VLBI) tracking of satellites is a topic of increasing interest for the establishment of space ties. This shall strengthen the connection of the various space geodetic techniques that contribute to the International Terrestrial Reference Frame. The concept of observing near-Earth satellites demands research on possible observing strategies. In this paper, we introduce this concept and discuss its possible benefits for improving future realizations of the International Terrestrial Reference System. Using simulated observations, we develop possible observing strategies that allow the determination of radio telescope <span class="hlt">positions</span> in the satellite system on Earth with accuracies of a few millimeters up to 1-2 cm for weekly station coordinates. This is shown for satellites with orbital heights between 2,000 and 6,000 km, observed by dense regional as well as by global VLBI-networks. The number of observations, as mainly determined by the satellite orbit and the observation interval, is identified as the most critical parameter that affects the expected accuracies. For observations of global <span class="hlt">positioning</span> system satellites, we propose the combination with classical VLBI to radio sources or a multi-satellite strategy. Both approaches allow station <span class="hlt">position</span> repeatabilities of a few millimeters for weekly solutions.</p> <div class="credits"> <p class="dwt_author">Plank, Lucia; Böhm, Johannes; Schuh, Harald</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">243</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920068544&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle"><span class="hlt">Precise</span> determination of earth's center of mass using measurements from the Global <span class="hlt">Positioning</span> System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Global <span class="hlt">Positioning</span> System (GPS) data from a worldwide geodetic experiment were collected during a 3-week period early in 1991. Geocentric station coordinates were estimated using the GPS data, thus defining a dynamically determined reference frame origin which should coincide with the earth center of mass, or geocenter. The 3-week GPS average geocenter estimates agree to 7-13 cm with geocenter estimates determined from satellite laser ranging, a well-established technique. The RMS of daily GPS geocenter estimates were 4 cm for x and y, and 30 cm for z.</p> <div class="credits"> <p class="dwt_author">Vigue, Yvonne; Lichten, Stephen M.; Blewitt, Geoffrey; Heflin, Michael B.; Malla, Rajendra P.</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">244</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890059905&hterms=dynamic+positioning&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Ddynamic%2Bpositioning"> <span id="translatedtitle">The dynamics of global <span class="hlt">positioning</span> system orbits and the determination of <span class="hlt">precise</span> ephemerides</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The suggestion made on the basis of the analytical orbit perturbation theory that the errors in the ephemerides of the GPS satellites are due mostly to resonant effects that can be corrected by adjusting a few parameters in a empirical acceleration formula is tested using simulations and actual data analysis. Data from the Spring 1985 Experiment were used to calculate improved ephemerides, and these ephemerides were used in the estimation of the coordinates of GPS stations within the continental United States, previously <span class="hlt">positioned</span> with VLBI. The results of this test support the idea that the errors are mostly of a resonant nature and can be corrected.</p> <div class="credits"> <p class="dwt_author">Colombo, Oscar L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">245</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=112146"> <span id="translatedtitle">Poliovirus Requires a <span class="hlt">Precise</span> 5? End for Efficient <span class="hlt">Positive</span>-Strand RNA Synthesis</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Poliovirus infectious RNA can be synthesized in vitro using phage DNA-dependent RNA-polymerases. These synthetic transcripts contain several extra nucleotides at the 5? end, which are deleted during replication to generate authentic viral genomes. We removed those 5?-end extra nucleotides utilizing a hammerhead ribozyme to produce transcripts with accurate 5? ends. These transcripts replicate substantially more rapidly in cell culture, demonstrating no lag before replication; they also replicate more efficiently in Xenopus laevis oocytes and in in vitro translation-replication cell extracts. In both systems, an exact 5? end is necessary for synthesis of <span class="hlt">positive</span>-strand RNA but not negative-strand RNA.</p> <div class="credits"> <p class="dwt_author">Herold, Jens; Andino, Raul</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">246</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010JAMDS...4..187Y"> <span id="translatedtitle"><span class="hlt">Precise</span> <span class="hlt">Positioning</span> Method for Logistics Tracking Systems Using Personal Handy-Phone System Based on Mahalanobis Distance</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Focusing on the Personal Handy-phone System (PHS) <span class="hlt">positioning</span> service used in physical distribution logistics, a <span class="hlt">positioning</span> error offset method for improving <span class="hlt">positioning</span> accuracy is invented. A disadvantage of PHS <span class="hlt">positioning</span> is that measurement errors caused by the fluctuation of radio waves due to buildings around the terminal are large, ranging from several tens to several hundreds of meters. In this study, an error offset method is developed, which learns patterns of <span class="hlt">positioning</span> results (latitude and longitude) containing errors and the highest signal strength at major logistic <span class="hlt">points</span> in advance, and matches them with new data measured in actual distribution processes according to the Mahalanobis distance. Then the matching resolution is improved to 1/40 that of the conventional error offset method.</p> <div class="credits"> <p class="dwt_author">Yokoi, Naoaki; Kawahara, Yasuhiro; Hosaka, Hiroshi; Sakata, Kenji</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">247</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920018554&hterms=Compliance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DCompliance"> <span id="translatedtitle"><span class="hlt">Precise</span> <span class="hlt">positioning</span> and compliance synthesis for automatic assembly using Lorentz levitation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Many manufacturing assembly tasks require fine compliant motion and fast, accurate <span class="hlt">positioning</span>. Conventional robots perform poorly in these tasks because of their large mass, friction and backlash in gears, cogging in drive motors and other deleterious effects. Even robots equipped with special control systems enabling compliant operation offer only partial solutions. It is difficult or impossible to automate many product assemblies requiring fine, compliant motion. This problem can be greatly alleviated by dividing the manipulation system into coarse and fine domains. In this scenario, a standard industrial robot can serve as a coarse positioner which in turn carries a six degrees of freedom fine motion wrist. Thus the robot can access a workspace measured in meters at low bandwidth and low resolution while the wrist can move over millimeters at high bandwidth and high resolution during the final phase of the assembly operation. Work indicates that fine motion wrists using Lorentz levitation can greatly augment the accuracy and dexterity of robots because they are frictionless, have high bandwidths and have a single back drivable moving part. Also, since there is no contact between the moving and stationary parts, wear and contamination can be eliminated. The use of six Lorentz force actuators in combination with real time <span class="hlt">position</span> and orientation sensing offers several important advantages over magnetic bearing approaches.</p> <div class="credits"> <p class="dwt_author">Hollis, R. L.; Salcudean, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">248</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014PhRvA..89e2516W"> <span id="translatedtitle">Kr-collision shift of the Rb D1 transition: The isoclinic <span class="hlt">point</span> and <span class="hlt">precision</span> optical spectroscopy</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Measuring the energy dependence of optical-transition collision shifts has proven extremely difficult, in part because of Doppler broadening and the manifold of overlapping hyperfine components that must be disentangled in the spectra. Here, we demonstrate an approach to these measurements based on spectroscopic isoclinic <span class="hlt">points</span>. To illustrate the approach's efficacy, we investigated the Kr collision shift of the Rb D1 transition at 795 nm. For the expected Rb-Kr van der Waals interaction, the collision shift should scale like (T/To)?, where To is a reference temperature and ?theo = 0.31. Exemplifying the difficulty of ? determinations, previous alkali-metal-noble-gas experimental measurements of ? have varied widely, sometimes in striking disagreement with theory (i.e., factor of 2 larger). In the present work, we not only demonstrate a measurement <span class="hlt">precision</span> better than 10-10/°C, but with our technique we validate the theoretical scaling constant, finding ?expt = 0.36 ± 0.06.</p> <div class="credits"> <p class="dwt_author">Wells, N. P.; Driskell, T. U.; Camparo, J. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">249</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22062236"> <span id="translatedtitle">Influence of a high vacuum on the <span class="hlt">precise</span> <span class="hlt">positioning</span> using an ultrasonic linear motor</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This paper presents an investigation of the ultrasonic linear motor stage for use in a high vacuum environment. The slider table is driven by the hybrid bolt-clamped Langevin-type ultrasonic linear motor, which is excited with its different modes of natural frequencies in both lateral and longitudinal directions. In general, the friction behavior in a vacuum environment becomes different from that in an environment of atmospheric pressure and this difference significantly affects the performance of the ultrasonic linear motor. In this paper, to consistently provide stable and high power of output in a high vacuum, frequency matching was conducted. Moreover, to achieve the fine control performance in the vacuum environment, a modified nominal characteristic trajectory following control method was adopted. Finally, the stage was operated under high vacuum condition, and the operating performances were investigated compared with that of a conventional PI compensator. As a result, robustness of <span class="hlt">positioning</span> was accomplished in a high vacuum condition with nanometer-level accuracy.</p> <div class="credits"> <p class="dwt_author">Kim, Wan-Soo; Lee, Dong-Jin; Lee, Sun-Kyu [School of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of)</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-15</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">250</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19840017025&hterms=etalon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Detalon"> <span id="translatedtitle">Design of a <span class="hlt">precision</span> etalon <span class="hlt">position</span> control system for a cryogenic spectrometer</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The Upper Atmosphere Research Satellite (UARS) will be launched in 1988 to study the distribution of a series of trace elements in the upper atmosphere and to study atmospheric dynamics. The UARS carries on board a cryogenically cooled infrared spectrometer to measure the concentration of a series of chemical species that are important for understanding the ozone layer in the stratosphere. This device, known as the Cryogenic Limb Array Etalon Spectrometer (CLAES), uses a multiposition filter wheel combined with tilt-scanned Fabry Perot etalons to obtain the high resolution required for these experiments. The CLAES optical system is sealed in a dewar where it is maintained at cryogenic temperatures by a supply of solid hydrogen. Operating temperatures for CLAES range from 130 K at the entrance aperture to 13 K at the focal plane. The design and test of a special control system using a unique actuator concept to provide <span class="hlt">position</span> and can control for the CLAES etalon are described. Results of performance tests at cryogenic temperatures simulating the CLAES on-orbit environment are discussed.</p> <div class="credits"> <p class="dwt_author">Aubrun, J. N.; Lorell, K. R.; Zacharie, D. F.; Thatcher, J. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">251</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1612829M"> <span id="translatedtitle">A new sensor system for accurate and <span class="hlt">precise</span> determination of sediment dynamics and <span class="hlt">position</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Sediment transport processes control many significant geomorphological changes. Consequently, sediment transport dynamics are studied across a wide range of scales leading to application of a variety of conceptually different mathematical descriptions (models) and data acquisition techniques (sensing). For river sediment transport processes both Eulerian and Lagrangian formulations are used. Data are gathered using a very wide range of sensing techniques that are not always compatible with the conceptual formulation applied. We are concerned with small to medium sediment grain-scale motion in gravel-bed rivers, and other coarse-grained environments, and: a) are developing a customised environmental sensor capable of providing coherent data that reliably record the motion; and, b) provide a mathematical framework in which these data can be analysed and interpreted, this being compatible with current stochastic approaches to sediment transport theory. Here we present results from three different aspects of the above developmental process. Firstly, we present a requirement analysis for the sensor based on the state of the art of the existing technologies. We focus on the factors that enhance data coherence and representativeness, extending the common practice for optimization which is based exclusively on electronics/computing related criteria. This analysis leads to formalization of a method that permits accurate control on the physical properties of the sensor using contemporary rapid prototyping techniques [Maniatis et al. 2013]. Secondly the first results are presented from a series of entrainment experiments in a 5 x 0.8 m flume in which a prototype sensor was deployed to monitor entrainment dynamics under increasing flow conditions (0.037 m3.s-1). The sensor was enclosed in an idealized spherical case (111 mm diameter) and placed on a constructed bed of hemispheres of the same diameter. We measured 3-axial inertial acceleration (as a measure of flow stress), with sampling frequency 4 to 10Hz, for two different initial <span class="hlt">positions</span> over a range of slopes (from 0.026 to 0.57). The results reveal forces during the pre-entrainment phase and show the effect of slope on the temporal characteristics of the process. Finally we present results from the simulations using a mathematical framework developed to integrate the inertial-dynamics data (corresponding to the above experimental procedure and sensing conceptualization) [Abeywardana et al. 2012] with the mathematical techniques used in contemporary localization applications [Zanella et al. 2012]. We specifically assess different signal filtering techniques in terms of: a) how informative they are regarding the complexity of sediment movement; and, b) how possible it is to reduce rapidly accumulating errors that occur during sensing and increase <span class="hlt">positional</span> accuracy. References Maniatis, G.; Hoey, T.; Sventek, J. Sensor Enclosures: Example Application and Implications for Data Coherence. J. Sens. Actuator Netw. 2013, 2, 761-779. Abeywardana, D. K., A. P. Hu, and N. Kularatna. "IPT charged wireless sensor module for river sedimentation detection." Sensors Applications Symposium (SAS), 2012 IEEE. IEEE, 2012. Zannella, Fillipo, and Angelo Cenedese. "Multi-agent tracking in wireless sensor networks: implementation." WSEAS Int. Conf. on Information Technology and Computer Networks (ITCN). 2012.</p> <div class="credits"> <p class="dwt_author">Maniatis, Georgios; Hoey, Trevor; Sventek, Joseph; Hodge, Rebecca</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">252</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22328430"> <span id="translatedtitle">Using recombineering to generate <span class="hlt">point</span> mutations:galK-based <span class="hlt">positive</span>-negative selection method.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Recombineering is a recombination-based highly efficient method of genetic engineering. It can be used to manipulate the bacterial chromosomal DNA as well as any episomal DNA. Recombineering can be used to insert selectable or nonselectable DNA fragments and subclone DNA fragments without the use of restriction enzymes and also to make <span class="hlt">precise</span> alterations including single nucleotide changes in the DNA. Here we describe a galactokinase (galK)-based two-step method to generate <span class="hlt">point</span> mutations in the bacterial artificial chromosome (BAC) insert using the recombineering technology. It takes advantage of the ability to select and also counterselect for the presence of galK. PMID:22328430</p> <div class="credits"> <p class="dwt_author">Biswas, Kajal; Stauffer, Stacey; Sharan, Shyam K</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">253</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/48923838"> <span id="translatedtitle"><span class="hlt">Pointed</span> water vapor radiometer corrections for accurate global <span class="hlt">positioning</span> system surveying</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Delay of the Global <span class="hlt">Positioning</span> System (GPS) signal due to atmospheric water vapor is a major source of error in GPS surveying. Improved vertical accuracy is important for sea level and polar isostasy measurements, geodesy, normal fault motion, subsidence, earthquake studies, air and ground-based gravimetry, ice dynamics, and volcanology. We conducted a GPS survey using water vapor radiometers (WVRs) <span class="hlt">pointed</span></p> <div class="credits"> <p class="dwt_author">Randolph Ware; Christian Rocken; Fredrick Solheim; Teresa Van Hove; Chris Alber; James Johnson</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">254</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.cosmic.ucar.edu/related_papers/Ware352.pdf"> <span id="translatedtitle"><span class="hlt">Pointed</span> water vapor radiometer corrections for accurate Global <span class="hlt">Positioning</span> System surveying</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Delay of the Global <span class="hlt">Positioning</span> System (GPS) signal due to atmospheric water vapor is a major source of error in GPS surveying. Improved vertical accuracy is important for sea level and polar isostasy measurements, geodesy, normal fault motion, subsidence, earthquake studies, air and ground-based gravimetry, ice dynamics, and volcanology. We conducted a GPS survey using water vapor radiometers (WVRs) <span class="hlt">pointed</span></p> <div class="credits"> <p class="dwt_author">Randolph Ware; Christian Rocken; Fredrick Solheim; Teresa Van Hove; Chris Alber; James Johnson</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">255</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010Metro..47..583Z"> <span id="translatedtitle">Adjustment of the measurement <span class="hlt">point</span>'s <span class="hlt">position</span> in a double-disc instrument for measuring an involute</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In all indexes of the accuracy of gears, the measurement of the error of an involute tooth profile is a difficult technical problem. A double-disc instrument for measuring an involute is introduced, the measuring principle of which is the same as the 'rolling artefact method' developed by PTB. In this paper, the measurement error caused by deviation of the measurement <span class="hlt">point</span> is analysed. In order to increase the <span class="hlt">position</span> accuracy of the measurement <span class="hlt">point</span>, a novel method called the 'error compensation method' is introduced, which searches for the best <span class="hlt">position</span> of the stylus by tentatively compensating the measurement error caused by deviation of the measurement <span class="hlt">point</span>. According to analysis and experiment, the stylus's adjustment deviation by the 'error compensation method' is 8 µm.</p> <div class="credits"> <p class="dwt_author">Zhifeng, Lou; Liding, Wang</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">256</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/14710830"> <span id="translatedtitle">High-<span class="hlt">precision</span> <span class="hlt">position</span>-specific isotope analysis of 13C/12C in leucine and methionine analogues.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We report an automated method for high-<span class="hlt">precision</span> <span class="hlt">position</span>-specific isotope analysis (PSIA) of carbon in amino acid analogues. Carbon isotope ratios are measured for gas-phase pyrolysis fragments from multiple sources of 3-methylthiopropylamine (3MTP) and isoamylamine (IAA), the decarboxylated analogues of methionine and leucine, using a home-built gas chromatography (GC)-pyrolysis-GC preparation system coupled to a combustion-isotope ratio mass spectrometry system. Over a temperature range of 620-900 degrees C, the characteristic pyrolysis products for 3MTP were CH4, C2H6, HCN, and CH3CN and for IAA products were propylene, isobutylene, HCN, and CH3CN. Fragment origin was confirmed by 13C-labeling, and fragments used for isotope analysis were generated from unique moieties with > 95% structural fidelity. Isotope ratios for the fragments were determined with an average <span class="hlt">precision</span> of SD(delta13C) < 0.3% per thousand, and relative isotope ratios of fragments from different sources were determined with an average <span class="hlt">precision</span> of SD(delta(delta)13C) < 0.5% per thousand. Delta(delta)13C values of fragments were invariant over a range of pyrolysis temperatures. The delta(delta)13C of complementary fragments in IAA was within 0.8% per thousand of the delta(delta)13C of the parent compounds, indicating that pyrolysis-induced isotopic fractionation is effectively taken into account with this calibration procedure. Using delta(delta)13C values of fragments, delta(delta)13C values were determined for all four carbon <span class="hlt">positions</span> of 3MTP and for C1, C2, and the propyl moiety of IAA, either directly or indirectly by mass balance. Large variations in <span class="hlt">position</span>-specific isotope ratios were observed in samples from different commercial sources. Most dramatically, two 3MTP sources differed by 16.30% per thousand at C1, 48.33% per thousand at C2, 0.37% per thousand at C3, and 5.36% per thousand at C(methyl). These PSIA techniques are suitable for studying subtle changes in intramolecular isotope ratios due to natural processes. PMID:14710830</p> <div class="credits"> <p class="dwt_author">Sacks, Gavin L; Brenna, J Thomas</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-10-15</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">257</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/9307103"> <span id="translatedtitle">Arm <span class="hlt">position</span> constraints during <span class="hlt">pointing</span> and reaching in 3-D space.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Arm movements in 3-D space were studied to investigate the reduction in the number of rotational degrees of freedom in the shoulder and elbow during <span class="hlt">pointing</span> movements with the fully extended arm and during <span class="hlt">pointing</span> movements to targets in various directions and at various distances relative to the shoulder, requiring flexion/extension in the elbow. The postures of both the upper arm and forearm can be described by rotation vectors, which represent these postures as a rotation from a reference <span class="hlt">position</span> to the current <span class="hlt">position</span>. The rotation vectors describing the posture of the upper arm and forearm were found to lie in a 2-D (curved) surface both for <span class="hlt">pointing</span> with the fully extended arm and for <span class="hlt">pointing</span> with elbow flexion. This result generalizes on previous results on the reduction of the number of degrees of freedom from three to two in the shoulder for the fully extended arm to a similar reduction in the number of degrees of freedom for the upper arm and forearm for normal arm movements involving also elbow flexion and extension. The orientation of the 2-D surface fitted to the rotation vectors describing the <span class="hlt">position</span> of the upper arm and forearm was the same for <span class="hlt">pointing</span> with the extended arm and for movements with flexion/extension of the elbow. The scatter in torsion of the rotation vectors describing the <span class="hlt">position</span> of the upper arm and forearm relative to the 2-D surface was typically 3-4 degrees, which is small considering the range of approximately 180 and 360 degrees for torsional rotations of the upper arm and the forearm, respectively. Donders' law states that arm posture for <span class="hlt">pointing</span> to a target does not depend on previous <span class="hlt">positions</span> of the arm. The results of our experiments demonstrate that the upper arm violates Donders' law. However, the variations in torsion of the upper arm are small, typically a few degrees. These deviations from Donders' law have been overlooked in previous studies, presumably because the variations are relatively small. These variations may explain the larger scatter of the rotation vectors for arm movements (3-4 degrees) than reported for the eye (1 degree). Unlike for saccadic eye movements, joint rotations in the shoulder during aiming movements were not all single-axis rotations. On the contrary, the direction of the angular velocity vector varied during the movement in a consistent and reproducible way, depending on amplitude, direction, and starting <span class="hlt">position</span> of the movement. These results reveal several differences between arm movements during <span class="hlt">pointing</span> and saccadic eye movements. The implications for our understanding of the coordination of eye and arm movements and for the planning of 3-D arm movements are discussed. PMID:9307103</p> <div class="credits"> <p class="dwt_author">Gielen, C C; Vrijenhoek, E J; Flash, T; Neggers, S F</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">258</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007PASP..119.1403J"> <span id="translatedtitle">Principal Component Analysis of the Time- and <span class="hlt">Position</span>-dependent <span class="hlt">Point</span>-Spread Function of the Advanced Camera for Surveys</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We describe the time- and <span class="hlt">position</span>-dependent <span class="hlt">point</span>-spread function (PSF) variation of the wide-field channel (WFC) of the Advanced Camera for Surveys (ACS) with the principal component analysis (PCA) technique. The time-dependent change is caused by the temporal variation of the HST focus, whereas the <span class="hlt">position</span>-dependent PSF variation in ACS WFC at a given focus is mainly the result of changes in aberrations and charge diffusion across the detector, which appear as <span class="hlt">position</span>-dependent changes in the elongation of the astigmatic core and blurring of the PSF, respectively. Using ˜ 20 ) of principal components or "eigen-PSFs" per exposure can robustly reproduce the observed variation of the ellipticity and size of the PSF. Our primary interest in this investigation is the application of this PSF library to <span class="hlt">precision</span> weak-lensing analyses, where accurate knowledge of the instrument's PSF is crucial. However, the high fidelity of the model judged from the nice agreement with observed PSFs suggests that the model is potentially also useful in other applications, such as crowded field stellar photometry, galaxy profile fitting, AGN studies, etc., which similarly demand a fair knowledge of the PSFs at objects' locations. Our PSF models, applicable to any WFC image rectified with the Lanczos3 kernel, are publicly available.</p> <div class="credits"> <p class="dwt_author">Jee, M. J.; Blakeslee, J. P.; Sirianni, M.; Martel, A. R.; White, R. L.; Ford, H. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">259</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AdRS...11..297G"> <span id="translatedtitle">Single-element based ultra-wideband antenna array concepts for wireless high-<span class="hlt">precision</span> 2-D local <span class="hlt">positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We generally categorize the approaches for ultra-wideband antenna array design, and consequently propose simplified concepts for antenna arrays for a high-<span class="hlt">precision</span>, ultra-wideband FMCW radar 2-D local <span class="hlt">positioning</span> system to obtain robustness against multi path interference, perform angle of arrival analysis, as well as instantaneous heading estimation. We focus on low-cost and mechanical robust, industrial-application ready antennas. The antenna arrays are optimized for operation in the 5 GHz to 8 GHz frequency range and are designed towards supporting full omnidirectional 360° as well as partial half-plane direction of arrival estimation. Two different concepts for vehicle- as well as wall-mounted antenna array systems are proposed and discussed. We propose a wideband unidirectional bow-tie antenna array element having 97% impedance and 37% pattern bandwidth and a robust vehicle mounted omnidirectional antenna element having more than 85% impedance and pattern bandwidth.</p> <div class="credits"> <p class="dwt_author">Gardill, M.; Fischer, G.; Weigel, R.; Koelpin, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">260</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006AGUFMGC23B1343K"> <span id="translatedtitle">Quantifying Uncertainty When no <span class="hlt">Precise</span> Probabilities are Available: The Example of Tipping <span class="hlt">Points</span> in the Earth System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Assessments of climate change often aim to capture the uncertainty about the findings in terms of probabilities. However, a variety of gaps in the available information can hamper the specification of <span class="hlt">precise</span> probabilities. Examples are (1) missing data for determining the likelihood function of pertinent climate system parameters, (2) disagreement about plausible prior probabilities for such parameters, and (3) uncertainty about the correlation between parameters in a multivariate problem. In these cases, imprecise probability theory may offer a remedy as it relaxes the informational requirements on the problem formulation and provides methods to work with large sets of prior probabilities and likelihood functions simultaneously. As an example, we consider the estimation of the (imprecise) probability of triggering tipping <span class="hlt">points</span> in the earth system under various greenhouse gas stabilization scenarios. The problem can be separated into two logical steps: (1) estimating the probability of climate change (in terms of global mean temperature (GMT) increase) for given stabilization scenarios, and (2) estimating the probability of triggering a tipping <span class="hlt">point</span> for given GMT increases. In the first step, we used a model-based approach to project uncertainties about climate sensitivity and ocean heat uptake onto future GMT increase, while relying on an expert elicitation for the second step. We use imprecise probability concepts to relax the requirements on a quantitative treatment of the information by (1) assuming a large set of probability distributions for climate sensitivity simultaneously, (2) assuming ignorance about the probability distribution for ocean heat diffusivity within bounds, (3) assuming ignorance about the correlation between the two climate parameters, (4) encouraging experts to express their imprecision about the probability of triggering, and (5) aggregating conflicting expert estimates in various ways. As a consequence, the number of contentious assumptions in the analysis is significantly reduced, but only intervals for the probability of triggering tipping <span class="hlt">points</span> under given stabilization scenarios can be obtained. We identify those sources of imprecision which have the strongest effect on the overall imprecision about the probability of triggering tipping <span class="hlt">points</span> in the earth system.</p> <div class="credits"> <p class="dwt_author">Kriegler, E.; Hall, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-12-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_12");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" 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showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_15");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">261</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.1252L"> <span id="translatedtitle">Regional gravity field modeling by the free-<span class="hlt">positioned</span> <span class="hlt">point</span> mass method</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The remove-compute-restore technique can be regarded as a state-of-the-art procedure for regional gravity field modeling, in which the long and short wavelength contributions from a spherical harmonic model and a DTM are first removed from the observations, then gravity field modeling techniques are applied to the residuals, and finally the corresponding long and short wavelength contributions are restored back. In this contribution the emphasis is on the second step, i.e., the compute or modeling step. Besides the classical integral and least-squares collocation (LSC) methods, the estimation based on radial basis functions is another interesting approach for regional gravity field modeling. The <span class="hlt">point</span> mass method belongs to the latter category, where the basis functions with respect to the disturbing potential are the reciprocal distances between the function and observation locations. The choice of the <span class="hlt">positions</span> and number of the <span class="hlt">point</span> masses plays a crucial role in this method, and even in other related estimation methods. In order to solve this problem, the concept of the free-<span class="hlt">positioned</span> <span class="hlt">point</span> masses proposed by Barthelmes (1986) seems to be a good choice, in which the <span class="hlt">point</span> masses are searched stepwise with simultaneous determination of the corresponding <span class="hlt">point</span> mass <span class="hlt">positions</span> and magnitudes within an iterative nonlinear least-squares approach. In this study, four different nonlinear iterative algorithms (Levenberg-Marquardt, L-BFGS, L-BFGS-B, and NLCG) have been implemented for regional gravity field modeling. The applicability and performance of each algorithm is demonstrated by two numerical tests with simulated and real data, respectively. In each test, different aspects (e.g., the use of original or reduced basis functions, the use of 2 or 4 parameters for each <span class="hlt">point</span> mass), affecting the quality of the solutions, are discussed. Furthermore, the results are compared to the classical LSC solutions.</p> <div class="credits"> <p class="dwt_author">Lin, Miao; Denker, Heiner; Müller, Jürgen</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">262</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51708102"> <span id="translatedtitle">Variable and fixed-<span class="hlt">point</span> blackbody sources developed at VNIIOFI for <span class="hlt">precision</span> measurements in radiometry and thermometry within 100K-3500K temperature range</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The demands of modern radiation thermometry and radiometry are being satisfied by a large variety of high-<span class="hlt">precision</span> unique BB sources (both fixed-<span class="hlt">point</span> and variable temperature) designed for a wide range of temperature from 100 K to 3500 K. The paper contains a detailed review of low-, medium- and high-temperature <span class="hlt">precision</span> blackbodies developed at VNIIOFI as the basis of the spectral</p> <div class="credits"> <p class="dwt_author">V. I. Sapritsky; B. B. Khlevnoy; S. A. Ogarev; V. E. Privalsky; M. L. Samoylov; M. K. Sakharov; A. A. Bourdakin; A. S. Panfilov</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">263</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008IJTP...47.1471T"> <span id="translatedtitle">PT-Symmetric Solutions of Schrödinger Equation with <span class="hlt">Position</span>-Dependent Mass via <span class="hlt">Point</span> Canonical Transformation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">PT-symmetric solutions of Schrödinger equation are obtained for the Scarf and generalized harmonic oscillator potentials with the <span class="hlt">position</span>-dependent mass. A general <span class="hlt">point</span> canonical transformation is applied by using a free parameter. Three different forms of mass distributions are used. A set of the energy eigenvalues of the bound states and corresponding wave functions for target potentials are obtained as a function of the free parameter.</p> <div class="credits"> <p class="dwt_author">Tezcan, Cevdet; Sever, Ramazan</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">264</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/15009755"> <span id="translatedtitle"><span class="hlt">Position</span> Estimation of Access <span class="hlt">Points</span> in 802.11 Wireless Networks</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We developed a technique to locate wireless network nodes using multiple time-of-flight range measurements in a <span class="hlt">position</span> estimate. When used with communication methods that allow propagation through walls, such as Ultra-Wideband and 802.11, we can locate network nodes in buildings and in caves where GPS is unavailable. This paper details the implementation on an 802.11a network where we demonstrated the ability to locate a network access <span class="hlt">point</span> to within 20 feet.</p> <div class="credits"> <p class="dwt_author">Kent, C A; Dowla, F U; Atwal, P K; Lennon, W J</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-12-05</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">265</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21544739"> <span id="translatedtitle">Tunable band gap near the Dirac <span class="hlt">point</span> in nonlinear negative-zero-<span class="hlt">positive</span> index metamaterial waveguide</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We make theoretical investigations of the nonlinear guided modes near the Dirac <span class="hlt">point</span> (DP) in nonlinear negative-zero-<span class="hlt">positive</span> index metamaterial (NZPIM) waveguide. When the nonlinearity is self-focusing, an asymmetric forbidden band exists near the DP that can be modulated by the strength of the nonlinearity. However, the self-defocusing nonlinearity can completely eliminate the asymmetric band gap. We also study the nonlinear surface waves in such nonlinear NZPIM waveguide. These results may predict analogous phenomena in nonlinear graphene.</p> <div class="credits"> <p class="dwt_author">Shen Ming; Ruan Linxu; Shi Jielong; Wang Qi [Department of Physics, Shanghai University, Shanghai 200444 (China); Wang Xinglin [Department of Applied Mathematics and Physics, Anhui Normal University, Wuhu 241000 (China)</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-04-15</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">266</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/11006399"> <span id="translatedtitle">High-<span class="hlt">precision</span> satellite <span class="hlt">positioning</span> system as a new tool to study the biomechanics of human locomotion.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">New Global <span class="hlt">Positioning</span> System (GPS) receivers allow now to measure a location on earth at high frequency (5Hz) with a centimetric <span class="hlt">precision</span> using phase differential <span class="hlt">positioning</span> method. We studied whether such technique was accurate enough to retrieve basic parameters of human locomotion. Eight subjects walked on an athletics track at four different imposed step frequencies (70-130steps/min) plus a run at free pace. Differential carrier phase localization between a fixed base station and the mobile antenna mounted on the walking person was calculated. In parallel, a triaxial accelerometer, attached to the low back, recorded body accelerations. The different parameters were averaged for 150 consecutive steps of each run for each subject (total of 6000 steps analyzed). We observed a perfect correlation between average step duration measured by accelerometer and by GPS (r=0.9998, N=40). Two important parameters for the calculation of the external work of walking were also analyzed, namely the vertical lift of the trunk and the velocity variation per step. For an average walking speed of 4.0km/h, average vertical lift and velocity variation were, respectively, 4.8cm and 0.60km/h. The average intra-individual step-to-step variability at a constant speed, which includes GPS errors and the biological gait style variation, were found to be 24. 5% (coefficient of variation) for vertical lift and 44.5% for velocity variation. It is concluded that GPS technique can provide useful biomechanical parameters for the analysis of an unlimited number of strides in an unconstrained free-living environment. PMID:11006399</p> <div class="credits"> <p class="dwt_author">Terrier, P; Ladetto, Q; Merminod, B; Schutz, Y</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">267</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1987PhRvA..35.4576B"> <span id="translatedtitle"><span class="hlt">Positions</span> of zeros in the bound-bound multipole matrix elements of the <span class="hlt">point</span> Coulomb field</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Minima in cross sections (Cooper minima) are known to occur for all types of transitions in atoms. These minima are caused by zeros in the transition matrix elements which are the result of a zero value for the radial integral of a particular energy. These minima can occur in both the bound-bound and bound-free transition matrix elements. In this paper the approximate <span class="hlt">position</span> (energy) of the zeros in the bound-bound quadrupole and octupole matrix elements of the <span class="hlt">point</span> Coulomb field are presented. The <span class="hlt">positions</span> are found to change in the same manner as those found in the continuum, even to the extent that a zero first occurring in a bound-bound matrix element will move into the corresponding bound-free matrix element.</p> <div class="credits"> <p class="dwt_author">Bronson, P. Fazio</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">268</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24977815"> <span id="translatedtitle">Paraxial analysis of three-component zoom lens with fixed distance between object and image <span class="hlt">points</span> and fixed <span class="hlt">position</span> of image-space focal <span class="hlt">point</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">This work performs an analysis of basic optical properties of zoom lenses with a fixed distance between object and image <span class="hlt">points</span> and a fixed <span class="hlt">position</span> of the image-space focal <span class="hlt">point</span>. Formulas for the calculation of paraxial parameters of such optical systems are derived and the calculation is presented on examples. PMID:24977815</p> <div class="credits"> <p class="dwt_author">Miks, Antonin; Novak, Jiri</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-30</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">269</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..12.6702W"> <span id="translatedtitle">Performance assessment of the COAMPS numerical weather prediction model in <span class="hlt">precise</span> GPS <span class="hlt">positioning</span>: EUPOS network case study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) represents a complete three-dimensional data assimilation system comprised of data quality control, analysis, initialization, and forecast model components. COAMPS has been developed by the Marine Meteorology Division (MMD) of the Naval Research Laboratory (NRL). The U.S. Navy uses the system for short-term numerical weather predictions for various regions of the world. Currently COAMPS ver.3.1 is also operated and tested at the Department of Civil Engineering and Geodesy of the Military University of Technology, Warsaw, Poland (MUT). It is primarily used for military applications, but also a new module has been developed to provide tropospheric zenith total delays (ZTD) for stations of the Polish part of the European <span class="hlt">Position</span> Determination System (EUPOS). ZTDs can be obtained in both near-real time and several hours ahead. In the highest-<span class="hlt">precision</span> GPS applications tropospheric delays are usually estimated from satellite observables. When processing long baselines the common practice is to derive the hydrostatic component from any troposphere model and use it as a priori information. The non-hydrostatic part is estimated in the adjustment along with station coordinates. The change of satellite geometry during the observational session allows overcome high correlation between the tropospheric delays and the station height components. However, when processing very short sessions and medium baselines, this change is too small and does not allow estimating reliable ZTDs. Hence, ZTD are derived from troposphere models and used for correction of GPS data in the processing. This contribution presents the application of COAMPS-derived ZTDs in <span class="hlt">precise</span> GPS <span class="hlt">positioning</span> when using short data spans (1-5 minutes) and processing medium baselines (50-80 km). The presented tests were performed in two areas: Wielkopolska Lowland (all stations located at similar heights), and Carpathian Mountains (where station height differences run into several hundreds of meters). The ZTDs derived from COAMPS model were used for correcting GPS observations. The ZTDs were mapped into slant delays using several mapping functions also these derived from numerical weather models (NWM), namely: VMF1, GMF, UNBab and Niell. Mapping functions and ZTD based on NWMs are said to provide the best troposphere modeling nowadays. About 200 sessions were processed in order to analyze accuracy and repeatability of the derived station coordinates. The results were compared to the ones obtained with application of simple Modified Hopfield model as well as well-established UNB3m neutral atmosphere model. Another tested and compared approach was the modelling of the tropospheric delays at the reference station network and then providing the interpolated corrections to the user receiver. All the processing was performed with use of GINPOS software developed at the University of Warmia and Mazury in Olsztyn (UWM).</p> <div class="credits"> <p class="dwt_author">Wielgosz, Pawel; Paziewski, Jacek; Krankowski, Andrzej; Kroszczynski, Krzyszfof; Figurski, Mariusz</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">270</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24057053"> <span id="translatedtitle">The effect of aborting ongoing movements on end <span class="hlt">point</span> <span class="hlt">position</span> estimation.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The present study investigated the impact of motor commands to abort ongoing movement on <span class="hlt">position</span> estimation. Participants carried out visually guided reaching movements on a horizontal plane with their eyes open. By setting a mirror above their arm, however, they could not see the arm, only the start and target <span class="hlt">points</span>. They estimated the <span class="hlt">position</span> of their fingertip based solely on proprioception after their reaching movement was stopped before reaching the target. The participants stopped reaching as soon as they heard an auditory cue or were mechanically prevented from moving any further by an obstacle in their path. These reaching movements were carried out at two different speeds (fast or slow). It was assumed that additional motor commands to abort ongoing movement were required and that their magnitude was high, low, and zero, in the auditory-fast condition, the auditory-slow condition, and both the obstacle conditions, respectively. There were two main results. (1) When the participants voluntarily stopped a fast movement in response to the auditory cue (the auditory-fast condition), they showed more underestimates than in the other three conditions. This underestimate effect was <span class="hlt">positively</span> related to movement velocity. (2) An inverted-U-shaped bias pattern as a function of movement distance was observed consistently, except in the auditory-fast condition. These findings indicate that voluntarily stopping fast ongoing movement created a negative bias in the <span class="hlt">position</span> estimate, supporting the idea that additional motor commands or efforts to abort planned movement are involved with the <span class="hlt">position</span> estimation system. In addition, spatially probabilistic inference and signal-dependent noise may explain the underestimate effect of aborting ongoing movement. PMID:24057053</p> <div class="credits"> <p class="dwt_author">Itaguchi, Yoshihiro; Fukuzawa, Kazuyoshi</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">271</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ISPAr.XL4..341Z"> <span id="translatedtitle">Study on Technology for <span class="hlt">Precision</span> Correction of Land Survey Data based on Plotting Result Data and Feature <span class="hlt">Points</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">High-<span class="hlt">precision</span> land survey data is important foundation for fine management of land resources and enhancement of land use efficiency. The main method for land survey is remote sensing (RS) survey. However, the accuracy of data gained through this method is susceptible to image map, boundary interpretation, plotting process and other factors. To improve the accuracy, the method of <span class="hlt">precision</span> correction of land investigation data that is based on high resolution image data with geometric correction model was discussed in detail. Technical test was conducted in some area of GuangZhou in China, and experimental results showed that the method can improve the accuracy of land survey data effectively.</p> <div class="credits"> <p class="dwt_author">Zeng, G.; Xie, S.; Peng, J.; Liu, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">272</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=DE89015629"> <span id="translatedtitle">Automated focal <span class="hlt">point</span> <span class="hlt">positioning</span> and emittance measurement procedure for the interaction <span class="hlt">point</span> of the SLC (Stanford Linear Collider).</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">To achieve maximum luminosity at the SLC, both the electron and positron beams must reach their minimum transverse size within 1 mm of the longitudinal location where the two bunches collide. This paper describes an automated procedure for <span class="hlt">positioning</span> the...</p> <div class="credits"> <p class="dwt_author">N. Phinney P. Bambade W. Kozanecki W. Koska</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">273</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1993BGeod..67...31L"> <span id="translatedtitle">The method of free-<span class="hlt">positioned</span> <span class="hlt">point</span> masses — geoid studies on the Gulf of Bothnia</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Gravity data inversion methods using spatial source distributions are frequently investigated and applied in Geodesy. Nearly all of them construct a fixed geometry for the sources. It was shown that this is not at all necessary. We give an approach to the problem of geoid determination based on free-<span class="hlt">positioned</span> <span class="hlt">point</span> masses. The algorithm available is extended and refined in order to make it applicable to more ill-designed and complex problems than addressed so far. We introduce concepts to handle different data accuracies, non-uniform data coverages, and different data types. The Gulf of Bothnia serves as an area of investigation. We determine a pure gravimetric geoid solution as well as a combined solution based on gravimetric and altimetric data. The problem of gross error detection in the altimetry is treated. The prediction accuracies obtained prove the method to be suitable for such a problem.</p> <div class="credits"> <p class="dwt_author">Lehmann, Rüdiger</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">274</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18468040"> <span id="translatedtitle">Optimal design of a double-sided linear motor with a multi-segmented trapezoidal magnet array for a high <span class="hlt">precision</span> <span class="hlt">positioning</span> system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A comparative analysis is performed for linear motors adopting conventional and multi-segmented trapezoidal (MST) magnet arrays, respectively, for a high-<span class="hlt">precision</span> <span class="hlt">positioning</span> system. The proposed MST magnet array is a modified version of a Halbach magnet array. The MST array has trapezoidal magnets with variable shape and dimensions while the Halbach magnet array generally has a rectangular magnet with identical dimensions.</p> <div class="credits"> <p class="dwt_author">Moon G. Lee; Dae-Gab Gweon</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">275</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1986PhRvA..34.3749B"> <span id="translatedtitle"><span class="hlt">Positions</span> of zeros in the multipole matrix elements of the <span class="hlt">point</span> Coulomb field</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Minima in the photoionization cross sections (Cooper minima) are known to occur for all types of transitions in atoms, even for dipole transitions from the ground state. These minima are caused by zeros in the transition matrix elements which are, in turn, the result of a zero value for the radial integral of a particular energy. For transitions involving the <span class="hlt">point</span> Coulomb field there are no zeros in the dipole matrix elements, but there are zeros in higher multipole transitions. The zeros in the quadrupole matrix elements involve transitions between low-angular-momentum bound states and free states with two more units of angular momentum. Zeros in octupole matrix elements fall into two categories. The first involves transitions between low-angular-momentum bound states and free states with three more units of angular momentum and the second involves transitions between all s and p states. In this paper the <span class="hlt">position</span> (energy) of the zeros in the multipole matrix elements of the <span class="hlt">point</span> Coulomb field are examined. Why the dipole matrix elements of hydrogen have no zeros and what causes the zeros in the higher-multipole matrix elements are then discussed.</p> <div class="credits"> <p class="dwt_author">Bronson, P. Fazio</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">276</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53177271"> <span id="translatedtitle">The NOVA satellite <span class="hlt">precise</span> ephemeris</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">An analysis of the NOVA satellite is presented emphasizing the generation of <span class="hlt">precise</span> ephemeris and limited <span class="hlt">point</span> <span class="hlt">positioning</span> results. Forcing functions for the satellite for such parameters as accelerations due to the gravitational fields of the earth, moon and sun, lunar and solar tidal distortions, and vehicle thrust were easily modelled according to a modification of the CELEST program (O'Toole,</p> <div class="credits"> <p class="dwt_author">R. E. Ziegler</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">277</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26610773"> <span id="translatedtitle"><span class="hlt">Precise</span> solutions of elastic-plastic crack line fields for cracked plate loaded by antiplane <span class="hlt">point</span> forces</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The elastic-plastic analysis for a cracked plate with finite dimensions is one of the most difficult fields of Elastic-Plastic Fracture Mechanics. In this paper, the improved near crack line field analysis method has been used to analyse a mode III center cracked plate with finite dimensions loaded by a pair of antiplane <span class="hlt">point</span> forces P at the center of the</p> <div class="credits"> <p class="dwt_author">Yi Zhi-Jian; Wang Shi-Jie; Wang Xiang-Jian</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">278</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24787189"> <span id="translatedtitle"><span class="hlt">Precise</span> determination of full matrix of piezo-optic coefficients with a four-<span class="hlt">point</span> bending technique: the example of lithium niobate crystals.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">A recently proposed technique representing a combination of digital imaging laser interferometry with a classical four-<span class="hlt">point</span> bending method is applied to a canonical nonlinear optical crystal, LiNbO?, to <span class="hlt">precisely</span> determine a full matrix of its piezo-optic coefficients (POCs). The contribution of a secondary piezo-optic effect to the POCs is investigated experimentally and analyzed theoretically. Based on the POCs thus obtained, a full matrix of strain-optic coefficients (SOCs) is calculated and the appropriate errors are estimated. A comparison of our experimental errors for the POCs and SOCs with the known reference data allows us to claim the present technique as the most <span class="hlt">precise</span>. PMID:24787189</p> <div class="credits"> <p class="dwt_author">Krupych, Oleg; Savaryn, Viktoriya; Vlokh, Rostyslav</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">279</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53215380"> <span id="translatedtitle">High-<span class="hlt">precision</span> kinematic GPS differential <span class="hlt">positioning</span> and integration of GPS with a ring laser strapdown inertial system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Many fields, such as geodetic surveying, <span class="hlt">positioning</span> of airborne sensors (photogrammetric cameras), laser bathymetry, airborne gravimetry, and hydrographic surveys, require accuracies in the decimeter or even centimeter range in differential <span class="hlt">positioning</span>. Using the full potential of the GPS in a dynamic environment, the Institute of Astronomical and Physical Geodesy (IAPG) has carried out several kinematic tests with respect to land-based,</p> <div class="credits"> <p class="dwt_author">Guenter W. Hein; Gerald Baustert; Bernd Eissfeller; Herbert Landau</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">280</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA167566"> <span id="translatedtitle">DMAHTC (Defense Mapping Agency Hydrographic/Topographic Center) GPS <span class="hlt">Point</span> <span class="hlt">Positioning</span> Software: Initial Results.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">Absolute <span class="hlt">positioning</span> software written at the Defense Mapping Agency Hydrographic/Topographic Center (DMAHTC) was designed to process Texas Instruments 4100 (TI 4100) geodetic receiver phase and range observations. This paper describes absolute <span class="hlt">positioning</span>...</p> <div class="credits"> <p class="dwt_author">T. E. Meyer G. T. Tennis J. A. Slater B. J. DeNoyer</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_13");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">281</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMED31A0700K"> <span id="translatedtitle">New Method for Determining Isotopic Values of Glutamic Acid and Phenylalanine for Estimation of <span class="hlt">Precise</span> Trophic <span class="hlt">Position</span> in Food Web Studies</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Compound Specific Isotope Analysis of Amino Acids (CSI-AA) has emerged as a highly <span class="hlt">precise</span> new method of determining trophic levels of both aquatic and terrestrial organisms. Multiple studies have now shown that ?15N values for glutamic acid (Glu) and phenylalanine (Phe) can be coupled to provide extremely <span class="hlt">precise</span> estimates of trophic <span class="hlt">position</span> in diverse food web studies. The standard gas chromatography—isotope ratio mass spectrometer (GC-IRMS) approach is presently limited to a select number of labs since necessary equipment is both expensive and not widely accessible. Furthermore, typical GC-IRMS ?15N <span class="hlt">precision</span> (±1‰) is significantly lower than usual bulk ?15N values (±0.1‰), thus presenting a considerable setback for <span class="hlt">precise</span> trophic level calculations. In this study, we develop a new dual-column method to purify Glu and Phe using high performance liquid chromatography (HPLC). Phe is purified using an analytical scale reverse phase column embedded with anionic ion-pairing reagents and collected using automated fraction collection. Glu is separated from the non-polar amino acids using the same column and further purified using a hydrophilic interaction liquid chromatography (HILIC) cation and anion-exchange column and collected via automated fraction collection. Isotopic analysis of the purified AAs is then conducted on an elemental analyzer—isotope ratio mass spectrometer (EA-IRMS). As a test of this method, we present and compare the trophic <span class="hlt">position</span> of five marine organisms—cyanobacteria, deep-sea bamboo coral, juvenile and adult white sea bass, and harbor seal, calculated using Glu and Phe ?15N values produced by both GC-IRMS and our HPLC-EA-IRMS approach. The preliminary results of this study suggest that the HPLC-EA-IRMS method is a viable alternative to GC-IRMS, which should allow accurate trophic <span class="hlt">position</span> estimates to be made by more researchers using more readily available instrumentation.</p> <div class="credits"> <p class="dwt_author">Kamath, T.; Broek, T.; McCarthy, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">282</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1989Navig..36...77H"> <span id="translatedtitle">High-<span class="hlt">precision</span> kinematic GPS differential <span class="hlt">positioning</span> and integration of GPS with a ring laser strapdown inertial system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Many fields, such as geodetic surveying, <span class="hlt">positioning</span> of airborne sensors (photogrammetric cameras), laser bathymetry, airborne gravimetry, and hydrographic surveys, require accuracies in the decimeter or even centimeter range in differential <span class="hlt">positioning</span>. Using the full potential of the GPS in a dynamic environment, the Institute of Astronomical and Physical Geodesy (IAPG) has carried out several kinematic tests with respect to land-based, shipborne, and airborne applications. After reviewing the main concepts in differential GPS kinematic <span class="hlt">positioning</span>, this paper presents experiences with and practical results of kinematic GPS tests. Results of a Kalman filter covariance analysis are shown for the integration of GPS phase and pseudorange data with ring laser strapdown inertial systems in order to recover cycle slips and short-time loss of lock in GPS. In particular, the question is discussed of the extent to which inertial strapdown systems can be used to bridge these times and to maintain centimeter accuracy.</p> <div class="credits"> <p class="dwt_author">Hein, Guenter W.; Baustert, Gerald; Eissfeller, Bernd; Landau, Herbert</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">283</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cim.mcgill.ca/~hamid/papers/CASIFMO03.pdf"> <span id="translatedtitle">Design of a One-Third Scale Multi-Tethered Aerostat System for <span class="hlt">Precise</span> <span class="hlt">Positioning</span> of a Radio Telescope Receiver</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The National Research Council of Canada's Herzberg Institute has proposed a design for a new radio telescope known as the 'Large Adaptive Reflector' (LAR). The LAR telescope is comprised of a 200 m reflector and a receiver held aloft at an altitude of 500 m by a tethered aerostat. The <span class="hlt">position</span> of the receiver is actively controlled by a series</p> <div class="credits"> <p class="dwt_author">Casey Lambert; Aaron Saunders; Curran Crawford; Meyer Nahon</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">284</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26604786"> <span id="translatedtitle">Investigation of wall's optimum insulation <span class="hlt">position</span> from maximum time lag and minimum decrement factor <span class="hlt">point</span> of view</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In this study, optimum insulation <span class="hlt">position</span> from maximum time lag and minimum decrement factor <span class="hlt">point</span> of view has been investigated numerically. For this purpose, one-dimensional transient heat conduction equation was solved for a composite wall using Crank–Nicolson's scheme under periodic convection boundary conditions. Four-centimeter thick insulation was placed in different <span class="hlt">positions</span> of 20-cm thick wall as a whole (1 piece,</p> <div class="credits"> <p class="dwt_author">H Asan</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">285</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=PB210906"> <span id="translatedtitle">Driver's Eye <span class="hlt">Position</span> Relative to the 'H' <span class="hlt">Point</span> for Trucks and Buses.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The eye <span class="hlt">position</span> of subjects has been measured while they were driving the prototype of a bus intended for public service and in a static mock up of this prototype. The average eye <span class="hlt">position</span> observed in these tests was confirmed by photographing profession...</p> <div class="credits"> <p class="dwt_author">H. P. R. Smith</p> <p class="dwt_publisher"></p> <p class="publishDate">1972-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">286</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cct.gfy.ku.dk/publ_cct/cct331.pdf"> <span id="translatedtitle">The <span class="hlt">precise</span> computation of geoid undulation differences with comparison to results obtained from the global <span class="hlt">positioning</span> system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Ellipsoidal height differences have been determined for 13 station pairs in the central Ohio region using measurements made with the Global <span class="hlt">Positioning</span> System. This information was used to compute geoid undulation differences based on known orthometric heights. These differences were compared to gravimetrically-computed undulations (using a Stokes integration procedure, and least squares collocation having an internal r.m.s. agreement of plus</p> <div class="credits"> <p class="dwt_author">Theo Engelis; R. H. Rapp; C. C. Tscherning</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">287</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/34738086"> <span id="translatedtitle">The effects of practice on movement distance and final <span class="hlt">position</span> reproduction: implications for the equilibrium-<span class="hlt">point</span> control of movements</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Predictions of two views on single-joint motor control, namely programming of muscle force patterns and equilibrium-<span class="hlt">point</span> control, were compared with the results of experiments with reproduction of movement distance and final location during fast unidirectional elbow flexions. Two groups of subjects were tested. The first group practiced movements over a fixed distance (36°), starting from seven different initial <span class="hlt">positions</span> (distance</p> <div class="credits"> <p class="dwt_author">Slobodan Jaric; Daniel M. Corcos; Gerald L. Gottlieb; Dusko B. Ilic; Mark L. Latash</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">288</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=%22lacuna%22&id=EJ866001"> <span id="translatedtitle">Cinderellas and Ugly Ducklings: <span class="hlt">Positive</span> Turning <span class="hlt">Points</span> in Students' Educational Careers--Exploratory Evidence and a Future Agenda</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary"><span class="hlt">Positive</span> turning <span class="hlt">points</span> touch upon the essence of education. They epitomize its power and reflect its core agenda: maximizing human capital. Paradoxically, previous studies have not looked into this important phenomenon. The current exploratory study fills this lacuna by building on extensive empirical research of key educational experiences to…</p> <div class="credits"> <p class="dwt_author">Yair, Gad</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">289</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22262537"> <span id="translatedtitle">Asynchronous decoding of finger <span class="hlt">position</span> and of EMG during <span class="hlt">precision</span> grip using CM cell activity: application to robot control.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Recent brain-machine interfaces (BMI) have demonstrated the use of intracortical signals for the kinematic control of robotic arms. However, for potential restoration of manual dexterity, two issues remain to be addressed: (1) Can hand and digit movements for dexterous manipulation be controlled in a similar way to arm movements? (2) Can the potentially large signal space for decoding of the many degrees of freedom (dof) of hand and digit movements be minimized? The first question addresses BMI control of dexterous prosthetic devices, while the second addresses the problem of whether few, but identified, neurons might provide adequate decoding. Asynchronous decoding of <span class="hlt">precision</span> grip finger movement kinematics from identified corticomotoneuronal (CM) cell activity was performed with an artificial neural network (ANN). After training over a given session, the ANNs successfully decoded trial-by-trial movement kinematics. Average accuracy over sessions was in the order of 80% and 50% for data sets of two monkeys respectively. Decoding accuracy increased as a function of (1) number of simultaneously recorded CM cells used for prediction, and (2) size of the sliding input window. Subsequently, a robot digit actuated by pneumatic artificial muscles, fed with the predicted trajectory, mimicked the recorded movement offline. Furthermore, CM cell signals were used for decoding of time-varying hand muscle EMG activity. The performance of EMG prediction tended to increase if CM cells that facilitated this particular muscle (compared to CM cells that facilitated other muscles) were used. These results provide evidence that an anthropomorphic robot finger can be controlled offline by spike trains recorded from identified corticospinal neurons. This represents a step towards neuroprosthetic devices for dexterous hand movements. PMID:22262537</p> <div class="credits"> <p class="dwt_author">Ouanezar, Sofiane; Eskiizmirliler, Selim; Maier, Marc A</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">290</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/6770225"> <span id="translatedtitle"><span class="hlt">Precision</span> translator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A <span class="hlt">precision</span> translator for focusing a beam of light on the end of a glass fiber which includes two turning fork-like members rigidly connected to each other. These members have two prongs each with its separation adjusted by a screw, thereby adjusting the orthogonal <span class="hlt">positioning</span> of a glass fiber attached to one of the members. This translator is made of simple parts with capability to keep adjustment even in condition of rough handling.</p> <div class="credits"> <p class="dwt_author">Reedy, R.P.; Crawford, D.W.</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-03-09</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">291</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/864839"> <span id="translatedtitle"><span class="hlt">Precision</span> translator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A <span class="hlt">precision</span> translator for focusing a beam of light on the end of a glass fiber which includes two turning fork-like members rigidly connected to each other. These members have two prongs each with its separation adjusted by a screw, thereby adjusting the orthogonal <span class="hlt">positioning</span> of a glass fiber attached to one of the members. This translator is made of simple parts with capability to keep adjustment even in condition of rough handling.</p> <div class="credits"> <p class="dwt_author">Reedy, Robert P. (Livermore, CA); Crawford, Daniel W. (Livermore, CA)</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">292</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011OptEn..50c5201C"> <span id="translatedtitle">Miniaturized suspension structure for <span class="hlt">precise</span> flying height <span class="hlt">positioning</span> measurement using a swing arm actuator with a holographic optical element module sensor</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This work presents a means of active actuation of the suspension structure with a holographic optical element (HOE) for the small-form-factor optical-disk drives. The proposed HOE module sensor is mounted on a swing arm swivel-drive mechanism with unique features, including a rotary actuator for tracking and a swing arm nutates along a pivot for focusing. The fabrication methodology for a cantilever-beam-like structure with HOE module sensor is investigated. Furthermore, the performances of optical module with swing arm-swivel actuation are experimentally evaluated to demonstrate the effectiveness of <span class="hlt">precise</span> flying height <span class="hlt">positioning</span> measurement method.</p> <div class="credits"> <p class="dwt_author">Chou, Po-Chien; Lin, Yu-Cheng; Cheng, Stone</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">293</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19910059796&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle">A scheme for reducing the effect of selective availability on <span class="hlt">precise</span> geodetic measurements from the Global <span class="hlt">Positioning</span> System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">From March to August 1990, the signals transmitted by the Block II satellites of the GPS were dithered under a policy of 'Selective Availability' (SA). The dithering appears as an about 10 to the -10th deviation of the satellite oscillator frequency, which, when accumulated over several minutes, can produce an error of about 100 cycles in the model for carrier beat phase. Differencing between simultaneously sampling receivers minimizes the error. If, however, the receivers do not sample simultaneously, it is necessary to model the frequency deviation. Such a model is here applied to data collected in March 1990 by TI4100 and Minimac receivers sampling at times separated by 0.92 s. Applying the algorithm significantly improves the rms scatter of the estimated relative <span class="hlt">position</span> vectors. The rms scatter from a data set including dithered satellites is similar for both simultaneously and nonsimultaneously sampling receivers, a result which indicates that SA can be adequately modeled.</p> <div class="credits"> <p class="dwt_author">Feigl, Kurt L.; King, Robert W.; Herring, Thomas A.; Rothacher, Markus</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">294</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23669686"> <span id="translatedtitle">Dynamic symmetrical pattern projection based laser triangulation sensor for <span class="hlt">precise</span> surface <span class="hlt">position</span> measurement of various material types.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">This paper describes a custom, material-type-independent laser-triangulation-based measurement system that utilizes a high-quality ultraviolet laser beam. Laser structuring applications demand material surface alignment regarding the laser focus <span class="hlt">position</span>, where fabrication conditions are optimal. Robust alignment of various material types was solved by introducing dynamic symmetrical pattern projection, and a "double curve fitting" centroid detection algorithm with subsurface scattering compensation. Experimental results have shown that the measurement system proves robust to laser intensity variation, with measurement bias lower than 50 ?m and standard deviation lower than ±6.3 ?m for all materials. The developed probe has been integrated into a PCB prototyping system for material referencing purposes. PMID:23669686</p> <div class="credits"> <p class="dwt_author">Žbontar, Klemen; Mihelj, Matjaž; Podobnik, Boštjan; Povše, Franc; Munih, Marko</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-20</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">295</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/20955459"> <span id="translatedtitle"><span class="hlt">Precision</span> Atomic Spectroscopy for Improved Limits on Variation of the Fine Structure Constant and Local <span class="hlt">Position</span> Invariance</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We report tests of local <span class="hlt">position</span> invariance and the variation of fundamental constants from measurements of the frequency ratio of the 282-nm {sup 199}Hg{sup +} optical clock transition to the ground state hyperfine splitting in {sup 133}Cs. Analysis of the frequency ratio of the two clocks, extending over 6 yr at NIST, is used to place a limit on its fractional variation of <5.8x10{sup -6} per change in normalized solar gravitational potential. The same frequency ratio is also used to obtain 20-fold improvement over previous limits on the fractional variation of the fine structure constant of |({alpha}/{alpha})|<1.3x10{sup -16} yr{sup -1}, assuming invariance of other fundamental constants. Comparisons of our results with those previously reported for the absolute optical frequency measurements in H and {sup 171}Yb{sup +} vs other {sup 133}Cs standards yield a coupled constraint of -1.5x10{sup -15}<{alpha}/{alpha}<0.4x10{sup -15} yr{sup -1} and -2.7x10{sup -15}<(d/dt)ln({mu}{sub Cs}/{mu}{sub B})<8.6x10{sup -15} yr{sup -1}.</p> <div class="credits"> <p class="dwt_author">Fortier, T. M. [P-23 Physics Division MS H803, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Time and Frequency Division MS 847, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Ashby, N.; Bergquist, J. C.; Delaney, M. J.; Diddams, S. A.; Heavner, T. P.; Hollberg, L.; Itano, W. M.; Jefferts, S. R.; Kim, K.; Levi, F.; Lorini, L.; Oskay, W. H.; Parker, T. E.; Shirley, J.; Stalnaker, J. E. [Time and Frequency Division MS 847, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-02-16</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">296</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/58836636"> <span id="translatedtitle">Concurrent Validity of Office Discipline Referrals and Cut <span class="hlt">Points</span> Used in Schoolwide <span class="hlt">Positive</span> Behavior Support</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Office discipline referrals (ODRs) are commonly used by school teams implementing school-wide <span class="hlt">positive</span> behavior support to indicate individual student need for additional behavior support. However, little is known about the technical adequacy of ODRs when used in this manner. In this study, the authors assessed a) the concurrent validity of number of ODRs received with a contemporary standardized behavior rating</p> <div class="credits"> <p class="dwt_author">Kent McIntosh; Amy L. Campbell; Deborah R. Carter; Bruno D. Zumbo</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">297</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004JMMM..281..336L"> <span id="translatedtitle">Optimal design of a double-sided linear motor with a multi-segmented trapezoidal magnet array for a high <span class="hlt">precision</span> <span class="hlt">positioning</span> system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A comparative analysis is performed for linear motors adopting conventional and multi-segmented trapezoidal (MST) magnet arrays, respectively, for a high-<span class="hlt">precision</span> <span class="hlt">positioning</span> system. The proposed MST magnet array is a modified version of a Halbach magnet array. The MST array has trapezoidal magnets with variable shape and dimensions while the Halbach magnet array generally has a rectangular magnet with identical dimensions. We propose a new model that can describe the magnetic field resulting from the complex-shaped magnets. The model can be applied to both MST and conventional magnet arrays. Using the model, a design optimization of the two types of linear motors is performed and compared. The magnet array with trapezoidal magnets can produce more force than one with rectangular magnets when they are arrayed in a linear motor where there is a yoke with high permeability. After the optimization and comparison, we conclude that the linear motor with the MST magnet array can generate more actuating force per volume than the motor with the conventional array. In order to satisfy the requirements of next generation systems such as high resolution, high speed, and long stroke, the use of a linear motor with a MST array as an actuator in a high <span class="hlt">precision</span> <span class="hlt">positioning</span> system is recommended from the results obtained here.</p> <div class="credits"> <p class="dwt_author">Lee, Moon G.; Gweon, Dae-Gab</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">298</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2649414"> <span id="translatedtitle"><span class="hlt">Positive</span> Fluorescent Selection Permits <span class="hlt">Precise</span>, Rapid, and In-Depth Overexpression Analysis in Plant Protoplasts1[C][OA</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Transient genetic modification of plant protoplasts is a straightforward and rapid technique for the study of numerous aspects of plant biology. Recent studies in metazoan systems have utilized cell-based assays to interrogate signal transduction pathways using high-throughput methods. Plant biologists could benefit from new tools that expand the use of cell culture for large-scale analysis of gene function. We have developed a system that employs fluorescent <span class="hlt">positive</span> selection in combination with flow cytometric analysis and fluorescence-activated cell sorting to isolate responses in the transformed protoplasts exclusively. The system overcomes the drawback that transfected protoplast suspensions are often a heterogeneous mix of cells that have and have not been successfully transformed. This Gateway-compatible system enables high-throughput screening of genetic circuitry using overexpression. The incorporation of a red fluorescent protein selection marker enables combined utilization with widely available green fluorescent protein (GFP) tools. For instance, such a dual labeling approach allows cytometric analysis of GFP reporter gene activation expressly in the transformed cells or fluorescence-activated cell sorting-mediated isolation and downstream examination of overexpression effects in a specific GFP-marked cell population. Here, as an example, novel uses of this system are applied to the study of auxin signaling, exploiting the red fluorescent protein/GFP dual labeling capability. In response to manipulation of the auxin response network through overexpression of dominant negative auxin signaling components, we quantify effects on auxin-responsive DR5?GFP reporter gene activation as well as profile genome-wide transcriptional changes specifically in cells expressing a root epidermal marker.</p> <div class="credits"> <p class="dwt_author">Bargmann, Bastiaan O.R.; Birnbaum, Kenneth D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">299</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3153812"> <span id="translatedtitle">Spatiotemporal Integration in Somatosensory Perception: Effects of Sensory Saltation on <span class="hlt">Pointing</span> at Perceived <span class="hlt">Positions</span> on the Body Surface</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">In the past, sensory saltation phenomena (Geldard and Sherrick, 1972) have been used repeatedly to analyze the spatiotemporal integration capacity of somatosensory and other sensory mechanisms by means of their psychophysical characteristic. The core phenomenon consists in a systematic mislocalization of one tactile stimulus (the attractee) toward another successive tactile stimulus (the attractant) presented at another location, increasing with shorter intervals. In a series of four experiments, sensory saltation characteristics were studied at the forearm and the abdomen. Participants reported the perceived <span class="hlt">positions</span> of attractees, attractants, and reference stimuli by <span class="hlt">pointing</span>. In general, saltation characteristics compared well to those reported in previous studies, but we were able to gain several new insights regarding this phenomenon: (a) the attractee–attractant interval did not exclusively affect the perceived attractee <span class="hlt">position</span>, but also the perceived attractant <span class="hlt">position</span>; (b) saltation characteristics were very similar at different body sites and orientations, but did show differences suggesting anisotropy (direction-dependency) in the underlying integration processes; (c) sensory saltation could be elicited with stimulation patterns crossing the body midline on the abdomen. In addition to the saltation-specific results, our experiments demonstrate that <span class="hlt">pointing</span> reports of perceived <span class="hlt">positions</span> on the body surface generally show pronounced systematic biases compared to veridical <span class="hlt">positions</span>, moderate intraindividual consistency, and a high degree of inter-individual variability. Finally, we address methodological and terminological controversies concerning the sensory saltation paradigm and discuss its possible neurophysiological basis.</p> <div class="credits"> <p class="dwt_author">Trojan, Jorg; Stolle, Annette M.; Carl, Antonija Mrsic; Kleinbohl, Dieter; Tan, Hong Z.; Holzl, Rupert</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">300</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005SPIE.5945..256O"> <span id="translatedtitle">The influence of the <span class="hlt">position</span> change of the anallactic <span class="hlt">point</span> on the accurate measuring in geodesy</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In the geodetic measuring instruments optical systems with internal focus are used at present. It enables reaching significant shortening of the optical set and the use of dust-proof mechanical construction of these systems. It results from the theoretical analysis of the optical features of these systems that the anallactical <span class="hlt">point</span> is not solid in the process of focusing but it is shifted along the optical system axis. This elaboration shows the impact of this shifting on accuracy of the geodetic measuring and suggests the way of compensation of this error during the measuring process.</p> <div class="credits"> <p class="dwt_author">Obr, Vitezslav</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-08-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_14");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" 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id="NextPageLink" onclick='return showDiv("page_17");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">301</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1983igss.conf..411Z"> <span id="translatedtitle">The NOVA satellite <span class="hlt">precise</span> ephemeris</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">An analysis of the NOVA satellite is presented emphasizing the generation of <span class="hlt">precise</span> ephemeris and limited <span class="hlt">point</span> <span class="hlt">positioning</span> results. Forcing functions for the satellite for such parameters as accelerations due to the gravitational fields of the earth, moon and sun, lunar and solar tidal distortions, and vehicle thrust were easily modelled according to a modification of the CELEST program (O'Toole, 1976). The NOVA pole <span class="hlt">position</span> solutions are almost a factor of two less noisy than those for Oscar satellite 30190. Initial <span class="hlt">position</span> corrections were significantly reduced in magnitude and more constant.</p> <div class="credits"> <p class="dwt_author">Ziegler, R. E.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">302</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20070034963&hterms=positioning&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2522positioning%2522"> <span id="translatedtitle">Real-Time <span class="hlt">Point</span> <span class="hlt">Positioning</span> Performance Evaluation of Single-Frequency Receivers Using NASA's Global Differential GPS System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This paper evaluates the performance of a single-frequency receiver using the 1-Hz differential corrections as provided by NASA's global differential GPS system. While the dual-frequency user has the ability to eliminate the ionosphere error by taking a linear combination of observables, the single-frequency user must remove or calibrate this error by other means. To remove the ionosphere error we take advantage of the fact that the magnitude of the group delay in range observable and the carrier phase advance have the same magnitude but are opposite in sign. A way to calibrate this error is to use a real-time database of grid <span class="hlt">points</span> computed by JPL's RTI (Real-Time Ionosphere) software. In both cases we evaluate the <span class="hlt">positional</span> accuracy of a kinematic carrier phase based <span class="hlt">point</span> <span class="hlt">positioning</span> method on a global extent.</p> <div class="credits"> <p class="dwt_author">Muellerschoen, Ronald J.; Iijima, Byron; Meyer, Robert; Bar-Sever, Yoaz; Accad, Elie</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">303</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920069573&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle">Crustal deformation measurements in central Japan determined by a Global <span class="hlt">Positioning</span> System fixed-<span class="hlt">point</span> network</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Results are presented from temporally dense measurements of crustal deformation associated with the convergence of the Eurasian (EUR), Pacific, North American, and Philippine Sea (PHS) plates, carried out in April 1988 by a 10-station GPS fixed-<span class="hlt">point</span> network established in central Japan. Using regional orbit relaxation methods, the analysis of the first 17-month data revealed significant horizontal deformation across the Suruga trough. Namely, it was found that a site in the northern tip of PHS plate moved nearly westward with a velocity of 28 +/-5 mm per year, and a site at the southeastern tip of EUR plate moved south-southwestward with a velocity of 18 +/-5 mm per year. A significant vertical uplift with a velocity of 20 mm/yr was detected at a site inland of the Tokai district located in the Akaishi uplift zone and at a site on the Hatsushima Island in Sagami Bay.</p> <div class="credits"> <p class="dwt_author">Shimada, Seiichi; Bock, Yehuda</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">304</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009APS..GECKTP015A"> <span id="translatedtitle"><span class="hlt">Positive</span> <span class="hlt">point</span>-to-plate corona discharge as influenced by different nitrogen pressure</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">An empirical formula for IV characteristics in the nitrogen pressure ranged between (Po-2.5Po) is presented for a <span class="hlt">point</span>-to-plate electrode corona discharge. Fast automatic data acquisition system is built to acquire the experimental data of the corona current and voltage and to determine the corona inception voltage. Three values of inception current (Io= 0.1, 0.5, and 1.0 ?A) are used to demonstrate that the minimum observed inception current gives more accurate inception voltage, for which the exponent n of a general formula I=A(V-Vo)^n has been optimized. The experimental investigation discloses that the inter-electrode separation S and the gas pressure have the strongest influence on both the dimensional parameter A and the corona inception voltage Vo. Of all potentially influential factors, a new empirical formula relating corona current, corona inception voltage, inter-electrode separation and gaps pressure is reached.</p> <div class="credits"> <p class="dwt_author">Azooz, Aasim A.; Wais, Sabah I.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">305</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014NDS...118..401C"> <span id="translatedtitle">Sensitivity Analysis for Reactor Period Induced by <span class="hlt">Positive</span> Reactivity Using One-<span class="hlt">point</span> Adjoint Kinetic Equation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In order to better predict a kinetic behavior of a nuclear fission reactor, an improvement of the delayed neutron parameters is essential. The present paper specifies important nuclear data for a reactor kinetics: Fission yield and decay constant data of 86Ge, some bromine isotopes, 94Rb, 98mY and some iodine isotopes. Their importance is quantified as sensitivities with a help of the adjoint kinetic equation, and it is found that they are dependent on an inserted reactivity (or a reactor period). Moreover, dependence of sensitivities on nuclear data files is also quantified using the latest files. Even though the currently evaluated data are used, there are large differences among different data files from a view <span class="hlt">point</span> of the delayed neutrons.</p> <div class="credits"> <p class="dwt_author">Chiba, G.; Tsuji, M.; Narabayashi, T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">306</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19900041492&hterms=well+ties&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwell%2Bties"> <span id="translatedtitle">A radio optical reference frame. I - <span class="hlt">Precise</span> radio source <span class="hlt">positions</span> determined by Mark III VLBI - Observations from 1979 to 1988 and a tie to the FK5</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Observations from 600 Mark III VLBI experiments from 1979 to 1988, resulting in 237,681 acceptable pairs of group delay and phase delay rate observations, have been used to derive <span class="hlt">positions</span> of 182 extragalactic radio sources with typical formal standard errors less than 1 mas. The sources are distributed fairly evenly above delta = -30 deg, and 70 sources have delta greater than 0 deg. Analysis with different troposphere models, as well as internal and external comparisons, indicates that a coordinate frame defined by this set of radio sources should be reliable at the 1 mas level. The right ascension zero <span class="hlt">point</span> of this reference frame has been aligned with the FK5 by using the optical <span class="hlt">positions</span> of 28 extragalactic radio sources whose <span class="hlt">positions</span> are on the FK5 system. Because of known defects in the knowledge of astronomical constants, daily nutation offsets in longitude and obliquity were determined relative to an arbitrary reference day in the set of experiments.</p> <div class="credits"> <p class="dwt_author">Ma, C.; Shaffer, D. B.; De Vegt, C.; Johnston, K. J.; Russell, J. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">307</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JGeod..88..463M"> <span id="translatedtitle">Application of SWACI products as ionospheric correction for single-<span class="hlt">point</span> <span class="hlt">positioning</span>: a comparative study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In Global Navigation Satellite Systems (GNSS) using L-band frequencies, the ionosphere causes signal delays that correspond with link related range errors of up to 100 m. In a first order approximation the range error is proportional to the total electron content (TEC) of the ionosphere. Whereas this first order range error can be corrected in dual-frequency measurements by a linear combination of carrier phase- or code-ranges of both frequencies, single-frequency users need additional information to mitigate the ionospheric error. This information can be provided by TEC maps deduced from corresponding GNSS measurements or by ionospheric models. In this paper we discuss and compare different ionospheric correction methods for single-frequency users. The focus is on the comparison of the <span class="hlt">positioning</span> quality using dual-frequency measurements, the Klobuchar model, the NeQuick model, the IGS TEC maps, the Neustrelitz TEC Model (NTCM-GL) and the reconstructed NTCM-GL TEC maps both provided via the ionosphere data service SWACI (http://swaciweb.dlr.de) in near real-time. For that purpose, data from different locations covering several days in 2011 and 2012 are investigated, including periods of quiet and disturbed ionospheric conditions. In applying the NTCM-GL based corrections instead of the Klobuchar model, <span class="hlt">positioning</span> accuracy improvements up to several meters have been found for the European region in dependence on the ionospheric conditions. Further in mid- and low-latitudes the NTCM-GL model provides results comparable to NeQuick during the considered time periods. Moreover, in regions with a dense GNSS ground station network the reconstructed NTCM-GL TEC maps are partly at the same level as the final IGS TEC maps.</p> <div class="credits"> <p class="dwt_author">Minkwitz, David; Gerzen, Tatjana; Wilken, Volker; Jakowski, Norbert</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">308</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24142968"> <span id="translatedtitle">Development of a simple and rapid method of <span class="hlt">precisely</span> identifying the <span class="hlt">position</span> of 10B atoms in tissue: an improvement in standard alpha autoradiography.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Boron neutron capture therapy (BNCT) can be utilized to selectively kill cancer cells using a boron compound that accumulates only in cancer cells and not in normal cells. Tumor-bearing animals treated by BNCT are routinely used to evaluate long-term antitumor effects of new boron compounds. Alpha-autoradiography is one of the methods employed in the evaluation of antitumor effects. However, a standard alpha-autoradiography cannot detect the microdistribution of (10)B because of the difficulty associated with the superposition of a tissue sample image and etched pits on a track detector with the etching process. In order to observe the microdistribution of (10)B, some special methods of alpha-autoradiography have been developed that make use of a special track detector, or the atomic force microscope combined with X-ray and UV light irradiation. In contrast, we propose, herein, a simple and rapid method of <span class="hlt">precisely</span> identifying the <span class="hlt">position</span> of (10)B using the imaging process and the shape of etched pits, such as their circularity, without the need to use special track detectors or a microscope. A brief description of this method and its verification test are presented in this article. We have established a method of detecting the microdistribution of (10)B with submicron deviation between the <span class="hlt">position</span> of etched pits and the <span class="hlt">position</span> of reaction in a tissue sample, for a given circularity of etched pits. PMID:24142968</p> <div class="credits"> <p class="dwt_author">Tanaka, Hiroki; Sakurai, Yoshinori; Suzuki, Minoru; Masunaga, Shin-ichiro; Takamiya, Koichi; Maruhashi, Akira; Ono, Koji</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">309</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ChPhB..23a8701Z"> <span id="translatedtitle"><span class="hlt">Position</span> difference regularity of corresponding R-wave peaks for maternal ECG components from different abdominal <span class="hlt">points</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We collected 343 groups of abdominal electrocardiogram (ECG) data from 78 pregnant women and deleted the channels unable for experts to determine R-wave peaks from them; then, based on these filtered data, the statistics of <span class="hlt">position</span> difference of corresponding R-wave peaks for different maternal ECG components from different <span class="hlt">points</span> were studied. The resultant statistics showed the regularity that the <span class="hlt">position</span> difference of corresponding maternal R-wave peaks between different abdominal <span class="hlt">points</span> does not exceed the range of 30 ms. The regularity was also proved using the fECG data from MIT—BIH PhysioBank. Additionally, the paper applied the obtained regularity, the range of <span class="hlt">position</span> differences of the corresponding maternal R-wave peaks, to accomplish the automatic detection of maternal R-wave peaks in the recorded all initial 343 groups of abdominal signals, including the ones with the largest fetal ECG components, and all 55 groups of ECG data from MIT—BIH PhysioBank, achieving the successful separation of the maternal ECGs.</p> <div class="credits"> <p class="dwt_author">Zhang, Jie-Min; Guan, Qun; Tang, Li-Ming; Liu, Tie-Bing; Liu, Hong-Xing; Huang, Xiao-Lin; Si, Jun-Feng</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">310</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=N7432446"> <span id="translatedtitle">Effects of Meteorological Conditions and Measurement <span class="hlt">Precision</span> on the Earth Trace of the Sonic Boom Wake (Extinction, Focalization) Influence des Conditions Meteorologiques et de Leur <span class="hlt">Precision</span> sur la <span class="hlt">Position</span> au Sol du Tapis de Bang (Extinction, Focallsation Sous Trace).</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The influence of meteorological conditions and the <span class="hlt">precision</span> of the measurement of meteorological parameters on the prediction of the aircraft sonic boom path on the ground is discussed. It was found that the sonic boom of the second sounding of the two d...</p> <div class="credits"> <p class="dwt_author">M. Schaffar F. Schlosser</p> <p class="dwt_publisher"></p> <p class="publishDate">1973-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">311</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006AGUFMGC51A0447A"> <span id="translatedtitle">Continuous Monitoring of Coastal Erosion in The Inupiat Eskimo Village of Barrow Alaska Using High <span class="hlt">Precision</span> Differential Global <span class="hlt">Positioning</span> System (DGPS)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Barrow Environmental Observatory (BEO) is a 7466 acre area that has been set aside for the sole purpose of scientific research and has been under intense studies for over 60 years under different projects. The BEO contains approximately 15 kilometers of coastline of which the majority have been monitored by Jerry Brown to calculate rates at which this is occurring. Coastal erosion is one of the many impacts resulting from global climate change in the Arctic. Sea ice in the Arctic Ocean is decreasing in extent and is also becoming less thick allowing wave height to increase, which in many areas has enhanced coastal erosion. In northern Alaska, the rate of coastal erosion appears to have increased dramatically over the last 50 years. This is cause for concern because of the increased potential damage to property, archeological sites and the ecology of the Arctic system. The central objective of this study was to determine the extent and nature of coastal erosion. In 2003, a new technique was used to monitor the coastal erosion by walking along the coastal bluff and logging Differential Global <span class="hlt">Positioning</span> Systems (DGPS) coordinates every second. In 2005, two kilometers of the coast was monitored and 15 km was monitored in 2006 using the same technique as in 2003. This new technique of walking the coastal bluff and logging coordinates every second with high <span class="hlt">precision</span> DGPS is coming out to be a very effective way to monitor coastal dynamics. Previous observations made by Jerry Brown state that at times up to 10m of coastal bluff per year have been lost to erosion. Using DGPS to monitor coastlines allows for application of GIS techniques to calculate area and volumetric rates at which the coastline is being eroded. This project will serve as a continuation of coastal erosion surveys and will be added as legacy data to the Barrow Area Information Database-Internet Map Server (www.baidims.org) .</p> <div class="credits"> <p class="dwt_author">Aguirre, A.; Tweedie, C. E.; Brown, J.; Graves, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">312</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011JASS...28...55C"> <span id="translatedtitle"><span class="hlt">Precision</span> Assessment of Near Real Time <span class="hlt">Precise</span> Orbit Determination for Low Earth Orbiter</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">precise</span> orbit determination (POD) of low earth orbiter (LEO) has complied with its required <span class="hlt">positioning</span> accuracy by the double-differencing of observations between International GNSS Service (IGS) and LEO to eliminate the common clock error of the global <span class="hlt">positioning</span> system (GPS) satellites and receiver. Using this method, we also have achieved the 1 m <span class="hlt">positioning</span> accuracy of Korea Multi-Purpose Satellite (KOMPSAT)-2. However double-differencing POD has huge load of processing the global network of lots of ground stations because LEO turns around the Earth with rapid velocity. And both the centimeter accuracy and the near real time (NRT) processing have been needed in the LEO POD applications--atmospheric sounding or urgent image processing--as well as the surveying. An alternative to differential GPS for high accuracy NRT POD is <span class="hlt">precise</span> <span class="hlt">point</span> <span class="hlt">positioning</span> (PPP) to use measurements from one satellite receiver only, to replace the broadcast navigation message with <span class="hlt">precise</span> post processed values from IGS, and to have phase measurements of dual frequency GPS receiver. PPP can obtain <span class="hlt">positioning</span> accuracy comparable to that of differential <span class="hlt">positioning</span>. KOMPSAT-5 has a <span class="hlt">precise</span> dual frequency GPS flight receiver (integrated GPS and occultation receiver, IGOR) to satisfy the accuracy requirements of 20 cm <span class="hlt">positioning</span> accuracy for highly <span class="hlt">precise</span> synthetic aperture radar image processing and to collect GPS radio occultation measurements for atmospheric sounding. In this paper we obtained about 3-5 cm <span class="hlt">positioning</span> accuracies using the real GPS data of the Gravity Recover and Climate Experiment (GRACE) satellites loaded the Blackjack receiver, a predecessor of IGOR. And it is important to reduce the latency of orbit determination processing in the NRT POD. This latency is determined as the volume of GPS measurements. Thus changing the sampling intervals, we show their latency to able to reduce without the <span class="hlt">precision</span> degradation as the assessment of their <span class="hlt">precision</span>.</p> <div class="credits"> <p class="dwt_author">Choi, Jong-Yeoun; Lee, Sang-Jeong</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">313</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/667317"> <span id="translatedtitle"><span class="hlt">Precision</span> locks</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper describes a new method for controlling data base concurrency, called <span class="hlt">precision</span> locks (PL). The name is derived from the fact that they lock <span class="hlt">precisely</span> the set of tuples required to guarantee data base consistency, phantoms included. This results in maximum concurrency among all tuple-level locking methods, including predicate locks. A framework for comparing locking systems which indicates the</p> <div class="credits"> <p class="dwt_author">J. R. Jordan; J. Banerjee; R. B. Batman</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">314</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/57070159"> <span id="translatedtitle"><span class="hlt">Precision</span> Controls</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Precision</span> Controls, a leading designer of industrial valve systems, has the opportunity to contract with Ashmore Chemicals, which produces phenol. Ashmore is trying to improve its safety record in light of terrorist activity and recent close calls at one of its plants. Ashmore wants to upgrade its current valves within the next nine months. In return, <span class="hlt">Precision</span> Controls has the</p> <div class="credits"> <p class="dwt_author">Sherwood Frey</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">315</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53304913"> <span id="translatedtitle">Research on <span class="hlt">pointing</span> of piezoelectric fast steering mirror under vibration condition</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Piezoelectric Fast Steering Mirror (PFSM) is widely used to realize fast and <span class="hlt">precise</span> <span class="hlt">pointing</span> in optical systems. To eliminate the nonlinearity, close-loop driving circuit must be used through <span class="hlt">position</span> sensors such as strain gauge. Since PFSM not only works in static condition, but also needs <span class="hlt">pointing</span> <span class="hlt">precisely</span> under dynamic condition, it is necessary to research the <span class="hlt">pointing</span> performance under shock</p> <div class="credits"> <p class="dwt_author">Bingna Zhang; Liang Zhang; Genghua Huang; Rong Shu</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">316</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/865062"> <span id="translatedtitle"><span class="hlt">Precision</span> manometer gauge</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A <span class="hlt">precision</span> manometer gauge which locates a zero height and a measured height of liquid using an open tube in communication with a reservoir adapted to receive the pressure to be measured. The open tube has a reference section carried on a <span class="hlt">positioning</span> plate which is moved vertically with machine tool <span class="hlt">precision</span>. Double scales are provided to read the height of the <span class="hlt">positioning</span> plate accurately, the reference section being inclined for accurate meniscus adjustment, and means being provided to accurately locate a zero or reference <span class="hlt">position</span>.</p> <div class="credits"> <p class="dwt_author">McPherson, Malcolm J. (Lafayette, CA); Bellman, Robert A. (Berkeley, CA)</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">317</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/5823456"> <span id="translatedtitle"><span class="hlt">Precision</span> manometer gauge</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A <span class="hlt">precision</span> manometer gauge which locates a zero height and a measured height of liquid using an open tube in communication with a reservoir adapted to receive the pressure to be measured. The open tube has a reference section carried on a <span class="hlt">positioning</span> plate which is moved vertically with machine tool <span class="hlt">precision</span>. Double scales are provided to read the height of the <span class="hlt">positioning</span> plate accurately, the reference section being inclined for accurate meniscus adjustment, and means being provided to accurately locate a zero or reference <span class="hlt">position</span>.</p> <div class="credits"> <p class="dwt_author">McPherson, M.J.; Bellman, R.A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-09-27</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">318</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/20079385"> <span id="translatedtitle">The differences in the isoelectric <span class="hlt">points</span> of biofilm-<span class="hlt">positive</span> and biofilm-negative Candida parapsilosis strains.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The isoelectric <span class="hlt">points</span> of 39 Candida parapsilosis strains were determined by means of capillary isoelectric focusing. The value of the isoelectric <span class="hlt">point</span> corresponded well with cell surface hydrophobicity, as well as with the ability to form biofilm in these yeasts. PMID:20079385</p> <div class="credits"> <p class="dwt_author">Ruzicka, Filip; Horka, Marie; Hola, Veronika; Kubesova, Anna; Pavlik, Tomas; Votava, Miroslav</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">319</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19830005672&hterms=rydberg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Drydberg"> <span id="translatedtitle">Rydberg-Klein-Rees 1-Sigma-<span class="hlt">positive</span> potential curve turning <span class="hlt">points</span> for the isotopes of carbon monoxide</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">First order RKR turning <span class="hlt">points</span> were computed for (C-12)O16, (C-12)O17, (C-13)O16, (C-12)O18, and (C-13)O18 for vibrational levels up to v = 40. These turning <span class="hlt">points</span> should be useful in the numerical computation of matrix elements of powers of the internuclear separation.</p> <div class="credits"> <p class="dwt_author">Chackerian, C., Jr.; Goorvitch, D.</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">320</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=calibration+AND+instruments&pg=2&id=ED020118"> <span id="translatedtitle">MEASUREMENT AND <span class="hlt">PRECISION</span>, EXPERIMENTAL VERSION.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">THIS DOCUMENT IS AN EXPERIMENTAL VERSION OF A PROGRAMED TEXT ON MEASUREMENT AND <span class="hlt">PRECISION</span>. PART I CONTAINS 24 FRAMES DEALING WITH <span class="hlt">PRECISION</span> AND SIGNIFICANT FIGURES ENCOUNTERED IN VARIOUS MATHEMATICAL COMPUTATIONS AND MEASUREMENTS. PART II BEGINS WITH A BRIEF SECTION ON EXPERIMENTAL DATA, COVERING SUCH <span class="hlt">POINTS</span> AS (1) ESTABLISHING THE ZERO <span class="hlt">POINT</span>, (2)…</p> <div class="credits"> <p class="dwt_author">Harvard Univ., Cambridge, MA. Harvard Project Physics.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_15");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">321</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005SPIE.5633...66Z"> <span id="translatedtitle">Study on the special vision sensor for detecting <span class="hlt">position</span> error in robot <span class="hlt">precise</span> TIG welding of some key part of rocket engine</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Rocket engine is a hard-core part of aerospace transportation and thrusting system, whose research and development is very important in national defense, aviation and aerospace. A novel vision sensor is developed, which can be used for error detecting in arc length control and seam tracking in <span class="hlt">precise</span> pulse TIG welding of the extending part of the rocket engine jet tube. The vision sensor has many advantages, such as imaging with high quality, compactness and multiple functions. The optics design, mechanism design and circuit design of the vision sensor have been described in detail. Utilizing the mirror imaging of Tungsten electrode in the weld pool, a novel method is proposed to detect the arc length and seam tracking error of Tungsten electrode to the center line of joint seam from a single weld image. A calculating model of the method is proposed according to the relation of the Tungsten electrode, weld pool, the mirror of Tungsten electrode in weld pool and joint seam. The new methodologies are given to detect the arc length and seam tracking error. Through analyzing the results of the experiments, a system error modifying method based on a linear function is developed to improve the detecting <span class="hlt">precise</span> of arc length and seam tracking error. Experimental results show that the final <span class="hlt">precision</span> of the system reaches 0.1 mm in detecting the arc length and the seam tracking error of Tungsten electrode to the center line of joint seam.</p> <div class="credits"> <p class="dwt_author">Zhang, Wenzeng; Chen, Nian; Wang, Bin; Cao, Yipeng</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">322</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/902341"> <span id="translatedtitle">A Flexure-Based Tool Holder for Sub-(micro)m <span class="hlt">Positioning</span> of a Single <span class="hlt">Point</span> Cutting Tool on a Four-axis Lathe</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A tool holder was designed to facilitate the machining of <span class="hlt">precision</span> meso-scale components with complex three-dimensional shapes with sub-{micro}m accuracy on a four-axis lathe. A four-axis lathe incorporates a rotary table that allows the cutting tool to swivel with respect to the workpiece to enable the machining of complex workpiece forms, and accurately machining complex meso-scale parts often requires that the cutting tool be aligned <span class="hlt">precisely</span> along the axis of rotation of the rotary table. The tool holder designed in this study has greatly simplified the process of setting the tool in the correct location with sub-{micro}m <span class="hlt">precision</span>. The tool holder adjusts the tool <span class="hlt">position</span> using flexures that were designed using finite element analyses. Two flexures adjust the lateral <span class="hlt">position</span> of the tool to align the center of the nose of the tool with the axis of rotation of the B-axis, and another flexure adjusts the height of the tool. The flexures are driven by manual micrometer adjusters, each of which provides a minimum increment of motion of 20 nm. This tool holder has simplified the process of setting a tool with sub-{micro}m accuracy, and it has significantly reduced the time required to set a tool.</p> <div class="credits"> <p class="dwt_author">Bono, M J; Hibbard, R L</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-12-05</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">323</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/872869"> <span id="translatedtitle"><span class="hlt">Precision</span> displacement reference system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A <span class="hlt">precision</span> displacement reference system is described, which enables real time accountability over the applied displacement feedback system to <span class="hlt">precision</span> machine tools, <span class="hlt">positioning</span> mechanisms, motion devices, and related operations. As independent measurements of tool location is taken by a displacement feedback system, a rotating reference disk compares feedback counts with performed motion. These measurements are compared to characterize and analyze real time mechanical and control performance during operation.</p> <div class="credits"> <p class="dwt_author">Bieg, Lothar F. (Albuquerque, NM); Dubois, Robert R. (Albuquerque, NM); Strother, Jerry D. (Edgewood, NM)</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-02-22</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">324</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/57853743"> <span id="translatedtitle">A Case Example of the Implementation of Schoolwide <span class="hlt">Positive</span> Behavior Support in a High School Setting Using Change <span class="hlt">Point</span> Test Analysis</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The purpose of this case study was to expand the literature base regarding the application of high school schoolwide <span class="hlt">positive</span> behavior support in an urban setting for practitioners and policymakers to address behavior issues. In addition, the study describes the use of the Change <span class="hlt">Point</span> Test as a method for analyzing time series data that are dependent in nature. The</p> <div class="credits"> <p class="dwt_author">Hank Bohanon; Pamela Fenning; Kira Hicks; Stacey Weber; Kimberly Thier; Brigit Aikins; Kelly Morrissey; Alissa Briggs; Gina Bartucci; Lauren McArdle; Lisa Hoeper; Larry Irvin</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">325</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014CG.....69...62Z"> <span id="translatedtitle">Adobe photoshop quantification (PSQ) rather than <span class="hlt">point</span>-counting: A rapid and <span class="hlt">precise</span> method for quantifying rock textural data and porosities</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Commonly used petrological quantification methods are visual estimation, counting, and image analyses. However, in this article, an Adobe Photoshop-based analyzing method (PSQ) is recommended for quantifying the rock textural data and porosities. Adobe Photoshop system provides versatile abilities in selecting an area of interest and the pixel number of a selection could be read and used to calculate its area percentage. Therefore, Adobe Photoshop could be used to rapidly quantify textural components, such as content of grains, cements, and porosities including total porosities and different genetic type porosities. This method was named as Adobe Photoshop Quantification (PSQ). The workflow of the PSQ method was introduced with the oolitic dolomite samples from the Triassic Feixianguan Formation, Northeastern Sichuan Basin, China, for example. And the method was tested by comparing with the Folk's and Shvetsov's "standard" diagrams. In both cases, there is a close agreement between the "standard" percentages and those determined by the PSQ method with really small counting errors and operator errors, small standard deviations and high confidence levels. The porosities quantified by PSQ were evaluated against those determined by the whole rock helium gas expansion method to test the specimen errors. Results have shown that the porosities quantified by the PSQ are well correlated to the porosities determined by the conventional helium gas expansion method. Generally small discrepancies (mostly ranging from -3% to 3%) are caused by microporosities which would cause systematic underestimation of 2% and/or by macroporosities causing underestimation or overestimation in different cases. Adobe Photoshop could be used to quantify rock textural components and porosities. This method has been tested to be <span class="hlt">precise</span> and accurate. It is time saving compared with usual methods.</p> <div class="credits"> <p class="dwt_author">Zhang, Xuefeng; Liu, Bo; Wang, Jieqiong; Zhang, Zhe; Shi, Kaibo; Wu, Shuanglin</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">326</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19790000566&hterms=toolmaker&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtoolmaker"> <span id="translatedtitle"><span class="hlt">Precision</span> scriber</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Device scribes fine lines to <span class="hlt">precise</span> tolerances on flat or round surfaces. Scriber is used in conjunction with toolmaker's microscope and will scribe metal of nonmetallic surfaces. When not in use, scriber is easily retracted or swung out of way so microscope can be used for other purposes.</p> <div class="credits"> <p class="dwt_author">Buzzard, R. J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1980-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">327</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA003974"> <span id="translatedtitle">Solution of Two-<span class="hlt">Point</span> Boundary-Value Problems with Jacobian Matrix Characterized by Large <span class="hlt">Positive</span> Eigenvalues.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This paper treats the nonlinear, two-<span class="hlt">point</span> boundary-value problem formulated by Troesch and studied by Roberts and Shipman. Computationally speaking, this is a difficult problem, owing to the fact that the Jacobian matrix is characterized by large positiv...</p> <div class="credits"> <p class="dwt_author">A. Miele A. K. Aggarwal J. L. Tietze</p> <p class="dwt_publisher"></p> <p class="publishDate">1973-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">328</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://files.eric.ed.gov/fulltext/ED539402.pdf"> <span id="translatedtitle">Response to the DIAC Discussion Paper: "Review of the General Skilled Migration <span class="hlt">Points</span> Test". Go8 <span class="hlt">Position</span> Paper</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">The Group of Eight (Go8) applauds the government's intention to comprehensively reform the skilled migration program, and it welcomes the opportunity to submit this response to the General Skilled Migration (GSM) <span class="hlt">Points</span> Test Discussion Paper. The Go8 has argued for some time that it is inappropriate to link international education to the skilled…</p> <div class="credits"> <p class="dwt_author">Group of Eight (NJ1), 2010</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">329</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2001SPIE.4272..181H"> <span id="translatedtitle">Novel active <span class="hlt">pointing</span> system for <span class="hlt">point-to-point</span> optical communication</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A unique active <span class="hlt">pointing</span> system for <span class="hlt">point-to-point</span> optical communications capitalizes on the limited angular travel requirements to achieve a high angular <span class="hlt">precision</span>, frictionless, lubrication-free design, at a price <span class="hlt">point</span> consistent with commercial production. Gimbal components and three design configurations were traded for performance, cost, reliability, and technical risk. A gimbal ring configuration with voice coil actuators, flexure bearings, and LVDT <span class="hlt">position</span> sensors was selected as the baseline, and prototypes were fabricated and assembled. Servo integration and testing is ongoing, which will be followed by commercial production.</p> <div class="credits"> <p class="dwt_author">Hiley, David J.; Mecherle, G. Stephen; Decanini, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">330</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.cosmic.ucar.edu/~braunj/papers/jaot_swv2003.pdf"> <span id="translatedtitle">Comparisons of Line-of-Sight Water Vapor Observations Using the Global <span class="hlt">Positioning</span> System and a <span class="hlt">Pointing</span> Microwave Radiometer</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Line-of-sight measurements of integrated water vapor from a global <span class="hlt">positioning</span> system (GPS) receiver and a microwave radiometer are compared. These two instruments were collocated at the central facility of the Department of Energy's Atmospheric Radiation Measurement Program's Southern Great Plains region, near Lamont, Oklahoma. The comparison was made using 47 days of observations in May and June of 2000. Weather</p> <div class="credits"> <p class="dwt_author">John Braun; Christian Rocken; James Liljegren</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">331</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19960018817&hterms=LVDT&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2522LVDT%2522"> <span id="translatedtitle">Sensing <span class="hlt">Position</span> With Approximately Constant Contact Force</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Computer-controlled electromechanical system uses number of linear variable-differential transformers (LVDTs) to measure axial <span class="hlt">positions</span> of selected <span class="hlt">points</span> on surface of lens, mirror, or other <span class="hlt">precise</span> optical component with high finish. Pressures applied to pneumatically driven LVDTs adjusted to maintain small, approximately constant contact forces as <span class="hlt">positions</span> of LVDT tips vary.</p> <div class="credits"> <p class="dwt_author">Sturdevant, Jay</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">332</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/4332380"> <span id="translatedtitle">State Observation Using the Phase and the Beat Frequency of a FMCW Radar for <span class="hlt">Precise</span> Local <span class="hlt">Positioning</span> and Line-of-Sight Detection</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The accuracy of an FMCW radar working in a multipath environment is mainly limited by the radar signal bandwidth. Furthermore, the separation and identification of line-of-sight (LOS) and non-line-of-sight (NLOS) signals are important and challenging problems in many radar and local <span class="hlt">positioning</span> applications. In this article, a method is proposed to overcome these restrictions. A state observer is used for</p> <div class="credits"> <p class="dwt_author">Stephan Max; Christian Bohn; Martin Vossiek</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">333</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/109688"> <span id="translatedtitle"><span class="hlt">Precision</span> Nova operations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">To improve the symmetry of x-ray drive on indirectly driven ICF capsules, we have increased the accuracy of operating procedures and diagnostics on the Nova laser. <span class="hlt">Precision</span> Nova operations includes routine <span class="hlt">precision</span> power balance to within 10% rms in the ``foot`` and 5% nns in the peak of shaped pulses, beam synchronization to within 10 ps rms, and <span class="hlt">pointing</span> of the beams onto targets to within 35 {mu}m rms. We have also added a ``fail-safe chirp`` system to avoid Stimulated Brillouin Scattering (SBS) in optical components during high energy shots.</p> <div class="credits"> <p class="dwt_author">Ehrlich, R.B.; Miller, J.L.; Saunders, R.L.; Thompson, C.E.; Weiland, T.L.; Laumann, C.W.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">334</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1999RScI...70.3488V"> <span id="translatedtitle">High-<span class="hlt">precision</span> hydraulic Stewart platform</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present a novel design for a Stewart platform (or hexapod), an apparatus which performs <span class="hlt">positioning</span> tasks with high accuracy. The platform, which is supported by six hydraulic telescopic struts, provides six degrees of freedom with 1 ?m resolution. Rotations about user defined pivot <span class="hlt">points</span> can be specified for any axis of rotation with microradian accuracy. Motion of the platform is performed by changing the strut lengths. Servo systems set and maintain the length of the struts to high <span class="hlt">precision</span> using proportional hydraulic valves and incremental encoders. The combination of hydraulic actuators and a design which is optimized in terms of mechanical stiffness enables the platform to manipulate loads of up to 20 kN. Sophisticated software allows direct six-axis <span class="hlt">positioning</span> including true path control. Our platform is an ideal support structure for a large variety of scientific instruments that require a stable alignment base with high-<span class="hlt">precision</span> motion.</p> <div class="credits"> <p class="dwt_author">van Silfhout, Roelof G.</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">335</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EurSS..46..484S"> <span id="translatedtitle">Effect of errors in <span class="hlt">positioning</span> the sampling <span class="hlt">points</span> on the assessment of the relationships between the remote sensing data and the soil properties</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The stochastic modeling of the shift in coordinates of the sampling <span class="hlt">points</span> was performed for a typical land plot in Bryansk opolie with the purpose to assess the influence of the accuracy of the sampling <span class="hlt">point</span> <span class="hlt">positioning</span> on the predicted properties of the plow horizon. It was proved that, for agro-gray soils, an occasional shift of the sampling <span class="hlt">points</span> by 2-6 m regarding the coordinates on satellite photographs of superhigh resolution may significantly change the correlation between the soil properties and the brightness in the infrared channel. Based on the modeling data, the 95% confidence interval was estimated for the possible correlation coefficients of such properties of the arable agro-gray soil as the density, moisture, specific surface, carbon, and mobile nitrogen content. The use of the brightness in the infrared channel as a covariate for building charts may noticeably improve the map's quality; however, it may unjustifiably complicate the mapping units delineation.</p> <div class="credits"> <p class="dwt_author">Samsonova, V. P.; Meshalkina, Yu. L.; Blagoveshchenskii, Yu. N.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">336</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003ESASP.535..397Y"> <span id="translatedtitle">The sharp rise of Lake Victoria, a <span class="hlt">positive</span> indicator to solar Wolf-Gleissberg cycles turning <span class="hlt">points</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Sun experiences cycles of the order 80-120 years known as the Wolf-Gleissberg (WG). Climate change occur at their turning <span class="hlt">points</span>. 1878 marked the end of a WG cycle and the beginning of a series of four low activity solar cycles. The induced 1878 sharp rise in Lake Victoria level was followed by a drop till 1890. Later on, the lake level rose and fall in sympathy with the weak solar cycles till 1922. Following the 1957 maximum of the next WG cycle a ~2.5 m sharp rise in Lake Victoria occurred. Again 1997 marked the end of the past WG cycle and the beginning of a new era of low activity solar cycles. As a consequence, the level of Lake Victoria rose sharply by 1.6 m and at present is dropping till the end of cycle 23 leading to drought conditions around 2009±2-3 years. Cyclic lake level will follow cycles 24 and 25 and possibly 26 when solar forcing will come to a holt.</p> <div class="credits"> <p class="dwt_author">Yousef, Shahinaz M.; Amer, Morsi</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">337</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3920874"> <span id="translatedtitle"><span class="hlt">Position</span>-addressable digital laser scanning <span class="hlt">point</span> fluorescence microscopy with a Blu-ray disk pickup head</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">A compact and <span class="hlt">position</span>-addressable blue ray scanning microscope (BSM) based on a commercially available Blu-ray disk pickup head (PUH) is developed for cell imaging with high resolution and low cost. The BSM comprises two objective lenses with numerical apertures (NAs) of 0.85 and 0.6 for focusing blue and red laser beams, respectively, on the sample slide. The blue and red laser beams are co-located adjacent to each other and move synchronously. A specially designed sample slide is used with a sample area and an address-patterned area for sample holding and address recognition, respectively. The blue laser beam is focused on the sample area and is used for fluorescent excitation and image capturing, whereas the red laser beam is focused on the address-patterned area and is used for address recognition and dynamic focusing. The address-patterned area is divided into 310 sectors. The cell image of each sector of the sampling area has a corresponding address pattern. Fluorescence images of monkey-derived kidney epithelial cells and fibroblast cells in which the F-actin is stained with fluorophore phalloidin CF 405 are measured by the BSM, with results comparable to those measured by a Leica TCS CP2 confocal microscope. The cell image of an area of interest can be easily tracked based on the coded address, and a large-area sample image can be accurately reconstructed from the sector images.</p> <div class="credits"> <p class="dwt_author">Tsai, Rung-Ywan; Chen, Jung-Po; Lee, Yuan-Chin; Huang, Chun-Chieh; Huang, Tai-Ting; Chiang, Hung-Chih; Cheng, Chih-Ming; Lo, Feng-Hsiang; Chang, Sheng-Li; Weng, Kuo-Yao; Chung, Lung-Pin; Chen, Jyh-Chern; Tiao, Golden</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">338</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/949683"> <span id="translatedtitle">Comparisons of line-of-sight water vapor observations using the global <span class="hlt">positioning</span> system and a <span class="hlt">pointing</span> microwave radiometer.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Line-of-sight measurements of integrated water vapor from a global <span class="hlt">positioning</span> system (GPS) receiver and a microwave radiometer are compared. These two instruments were collocated at the central facility of the Department of Energy's Atmospheric Radiation Measurement Program's Southern Great Plains region, near Lamont, Oklahoma. The comparison was made using 47 days of observations in May and June of 2000. Weather conditions during this time period were variable with total integrated water vapor ranging from less than 10 to more than 50 mm. To minimize errors in the microwave radiometer observations, observations were compared during conditions when the liquid water measured by the radiometer was less than 0.1 mm. The linear correlation of the observations between the two instruments is 0.99 with a root-mean-square difference of the GPS water vapor to a linear fit of the microwave radiometer of 1.3 mm. The results from these comparisons are used to evaluate the ability of networks of GPS receivers to measure instantaneous line-of-sight integrals of water vapor. A discussion and analysis is provided regarding the additional information of the water vapor field contained in these observations compared to time- and space-averaged zenith and gradient measurements.</p> <div class="credits"> <p class="dwt_author">Braun, J.; Rocken, C.; Liljegren, J. C.; Environmental Research; Univ. Corporation for Atmospheric Research</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">339</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/41136652"> <span id="translatedtitle">Using Global <span class="hlt">Positioning</span> System techniques in landslide monitoring</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The <span class="hlt">precise</span> determination of <span class="hlt">point</span> coordinates with conventional Global <span class="hlt">Positioning</span> System (GPS) techniques often required observation times of one to several hours. In the last few years, new GPS methods have been developed (among them, the fast-static and real time kinematic), with higher productivity and good theoretical <span class="hlt">precision</span>. The main objective of this paper is to ascertain the performance of</p> <div class="credits"> <p class="dwt_author">Josep A. Gili; Jordi Corominas; Joan Rius</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">340</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20040110726&hterms=ATTITUDES+PUBLIC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DATTITUDES%2BPUBLIC"> <span id="translatedtitle">Instrument Attitude <span class="hlt">Precision</span> Control</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A novel approach is presented in this paper to analyze attitude <span class="hlt">precision</span> and control for an instrument gimbaled to a spacecraft subject to an internal disturbance caused by a moving component inside the instrument. Nonlinear differential equations of motion for some sample cases are derived and solved analytically to gain insight into the influence of the disturbance on the attitude <span class="hlt">pointing</span> error. A simple control law is developed to eliminate the instrument <span class="hlt">pointing</span> error caused by the internal disturbance. Several cases are presented to demonstrate and verify the concept presented in this paper.</p> <div class="credits"> <p class="dwt_author">Juang, Jer-Nan</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_16");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a 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title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">341</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/963791"> <span id="translatedtitle"><span class="hlt">Precision</span> laser aiming system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A <span class="hlt">precision</span> laser aiming system comprises a disrupter tool, a reflector, and a laser fixture. The disrupter tool, the reflector and the laser fixture are configurable for iterative alignment and aiming toward an explosive device threat. The invention enables a disrupter to be quickly and accurately set up, aligned, and aimed in order to render safe or to disrupt a target from a standoff <span class="hlt">position</span>.</p> <div class="credits"> <p class="dwt_author">Ahrens, Brandon R. (Albuquerque, NM); Todd, Steven N. (Rio Rancho, NM)</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-28</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">342</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/16784263"> <span id="translatedtitle">Energy gradients with respect to atomic <span class="hlt">positions</span> and cell parameters for the Kohn-Sham density-functional theory at the Gamma <span class="hlt">point</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The application of theoretical methods based on density-functional theory is known to provide atomic and cell parameters in very good agreement with experimental values. Recently, construction of the exact Hartree-Fock exchange gradients with respect to atomic <span class="hlt">positions</span> and cell parameters within the Gamma-<span class="hlt">point</span> approximation has been introduced. In this article, the formalism is extended to the evaluation of analytical Gamma-<span class="hlt">point</span> density-functional atomic and cell gradients. The infinite Coulomb summation is solved with an effective periodic summation of multipole tensors. While the evaluation of Coulomb and exchange-correlation gradients with respect to atomic <span class="hlt">positions</span> are similar to those in the gas phase limit, the gradients with respect to cell parameters needs to be treated with some care. The derivative of the periodic multipole interaction tensor needs to be carefully handled in both direct and reciprocal space and the exchange-correlation energy derivative leads to a surface term that has its origin in derivatives of the integration limits that depend on the cell. As an illustration, the analytical gradients have been used in conjunction with the QUICCA algorithm to optimize one-dimensional and three-dimensional periodic systems at the density-functional theory and hybrid Hartree-Fock/density-functional theory levels. We also report the full relaxation of forsterite supercells at the B3LYP level of theory. PMID:16784263</p> <div class="credits"> <p class="dwt_author">Weber, Valéry; Tymczak, Christopher J; Challacombe, Matt</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-06-14</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">343</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=https://scout.wisc.edu/Reports/NSDL/MET/2003/met-031010#TopicInDepth"> <span id="translatedtitle"><span class="hlt">Precision</span> Machining</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">Basic machining processes are introduced on a Web site that is devoted to engineering fundamentals (1). Descriptions and illustrations of drilling, turning, grinding, and other common processes are provided for people with little to no prior machining knowledge. A waterjet is a non-traditional machining technology that uses high pressure streams of water with abrasive additives rather than solid cutting instruments to slice through metal and other materials. An in-depth discussion of waterjet operation and applications is available from Southern Methodist University (2). Waterjets are often cited as being much more <span class="hlt">precise</span> than traditional machining techniques. The Waterjet Video Vault (3) contains clips of waterjet machines in action. The video of the foam cutting procedure is especially interesting, as it shows how quick and accurate the machining process can be. An online guide to cross process machining, which incorporates elements from various conventional and unconventional techniques, is provided by the Mechanical Engineering Department at Columbia University (4). Some remarkable and innovative techniques that have surfaced over the past few years are outlined, including underwater laser machining and plasma-assisted machining. Entirely different and exotic machining techniques are required for creating microelectromechanical systems (MEMS) and other extremely small devices. The Caltech Micromachining Laboratory (5) maintains an archive of research highlights and papers on its homepage, including a paper on a MEMS-driven flapping wing for a palm-sized aerial vehicle. An online article from Modern Machine Shop (6) outlines some new technologies and research in the area of high speed machining. A particularly interesting section of the article describes a system developed at the University of Florida that aims to enable micromachining to achieve rotational speeds of standard machining processes, specifically up to a half million rotations per minute. Cutting edge waterjet innovations are the subject of a February 2003 feature from a publication of the Society of Manufacturing Engineers (7). Extremely high pressure nozzles are being developed to improve cutting speed, and enhanced software for controlling machine movements is also a focus of study. This news article (8) from June 20, 2003 describes an electrochemical machining process that is being used to fabricate complex nanostructures. The work, produced by German and U.S. researchers, has the potential to compete with current lithographic processes.</p> <div class="credits"> <p class="dwt_author">Leske, Cavin.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">344</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24671789"> <span id="translatedtitle">Optimal <span class="hlt">Positive</span> Cutoff <span class="hlt">Points</span> for careHPV Testing of Clinician- and Self-Collected Specimens in Primary Cervical Cancer Screening: an Analysis from Rural China.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">careHPV, a lower-cost DNA test for human papillomavirus (HPV), is being considered for cervical cancer screening in low- and middle-income countries. However, not a single large-scaled study exists to investigate the optimal <span class="hlt">positive</span> cutoff <span class="hlt">point</span> of careHPV test. We pooled data for 9,785 women participating in two individual studies conducted from 2007 to 2011 in rural China. Woman underwent multiple screening tests, including careHPV on clinician-collected specimens (careHPV-C) and self-collected specimens (careHPV-S), and Hybrid Capture 2 on clinician-collected specimens (HC2-C) as a reference standard. The primary endpoint was cervical intraepithelial neoplasia grade 3 or more severe (CIN3+) (n = 127), and secondary endpoint was CIN2+ (n = 213). The area under the curves (AUCs) for HC2-C and careHPV-C were similar (0.954 versus 0.948, P = 0.166), and better than careHPV-S (0.878; P < 0.001 versus both). The optimal <span class="hlt">positive</span> cutoff <span class="hlt">points</span> for HC2-C, careHPV-C, and careHPV-S were 1.40, 1.74, and 0.85, respectively. At the same cutoff <span class="hlt">point</span>, careHPV-C was not significantly less sensitive and more specific for CIN3+ than HC2-C, and careHPV-S was significantly less sensitive for CIN3+ than careHPV-C and HC2-C. Raising the cutoff <span class="hlt">point</span> of careHPV-C from 1.0 to 2.0 could result in nonsignificantly lower sensitivity but significantly higher specificity. Similar results were observed using CIN2+ endpoint. careHPV using either clinician- or self-collected specimens performed well in detecting cervical precancer and cancer. We found that the optimal cutoff <span class="hlt">points</span> of careHPV were 2.0 on clinician-collected specimens and 1.0 on self-collected specimens. PMID:24671789</p> <div class="credits"> <p class="dwt_author">Kang, Le-Ni; Jeronimo, Jose; Qiao, You-Lin; Zhao, Fang-Hui; Chen, Wen; Valdez, Melissa; Zhang, Xun; Bansil, Pooja; Paul, Proma; Bai, Ping; Peck, Roger; Li, Jing; Chen, Feng; Stoler, Mark H; Castle, Philip E</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">345</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/6153274"> <span id="translatedtitle"><span class="hlt">Precision</span> synchrotron radiation detectors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary"><span class="hlt">Precision</span> detectors to measure synchrotron radiation beam <span class="hlt">positions</span> have been designed and installed as part of beam energy spectrometers at the Stanford Linear Collider (SLC). The distance between pairs of synchrotron radiation beams is measured absolutely to better than 28 /mu/m on a pulse-to-pulse basis. This contributes less than 5 MeV to the error in the measurement of SLC beam energies (approximately 50 GeV). A system of high-resolution video cameras viewing <span class="hlt">precisely</span>-aligned fiducial wire arrays overlaying phosphorescent screens has achieved this accuracy. Also, detectors of synchrotron radiation using the charge developed by the ejection of Compton-recoil electrons from an array of fine wires are being developed. 4 refs., 5 figs., 1 tab.</p> <div class="credits"> <p class="dwt_author">Levi, M.; Rouse, F.; Butler, J.; Jung, C.K.; Lateur, M.; Nash, J.; Tinsman, J.; Wormser, G.; Gomez, J.J.; Kent, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">346</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920014298&hterms=CSR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2522CSR%2522"> <span id="translatedtitle"><span class="hlt">Precision</span> GPS ephemerides and baselines</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Based on the research, the area of <span class="hlt">precise</span> ephemerides for GPS satellites, the following observations can be made pertaining to the status and future work needed regarding orbit accuracy. There are several aspects which need to be addressed in discussing determination of <span class="hlt">precise</span> orbits, such as force models, kinematic models, measurement models, data reduction/estimation methods, etc. Although each one of these aspects was studied at CSR in research efforts, only <span class="hlt">points</span> pertaining to the force modeling aspect are addressed.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">347</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_navigation/cub_navigation_lesson08_activity1.xml"> <span id="translatedtitle">State Your <span class="hlt">Position</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">To navigate, you must know roughly where you stand relative to your designation, so you can head in the right direction. In locations where landmarks are not available to help navigate (in deserts, on seas), objects in the sky are the only reference <span class="hlt">points</span>. While celestial objects move fairly predictably, and rough longitude is not too difficult to find, it is not a simple matter to determine latitude and <span class="hlt">precise</span> <span class="hlt">positions</span>. In this activity, students investigate the uses and advantages of modern GPS for navigation.</p> <div class="credits"> <p class="dwt_author">Integrated Teaching And Learning Program</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">348</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26349032"> <span id="translatedtitle">Development of a micro-depth control system for an ultra-<span class="hlt">precision</span> lathe using a piezo-electric actuator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Micro-<span class="hlt">positioning</span> systems using piezo-electric actuators have very wide applications, for example as in ultra-<span class="hlt">precision</span> machine tools, optical devices and measurement systems In order to keep a high-<span class="hlt">precision</span> displacement resolution, they use a <span class="hlt">position</span> sensor and feed back the error. From the practical <span class="hlt">point</span> of view, high-resolution displacement sensor systems are very expensive and it is difficult to guarantee such sensitive</p> <div class="credits"> <p class="dwt_author">Jeong-Du Kim; Soo-Ryong Nam</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">349</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70039512"> <span id="translatedtitle">Ground control requirements for <span class="hlt">precision</span> processing of ERTS images</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">With the successful flight of the ERTS-1 satellite, orbital height images are available for <span class="hlt">precision</span> processing into products such as 1:1,000,000-scale photomaps and enlargements up to 1:250,000 scale. In order to maintain <span class="hlt">positional</span> error below 100 meters, control <span class="hlt">points</span> for the <span class="hlt">precision</span> processing must be carefully selected, clearly definitive on photos in both X and Y. Coordinates of selected control <span class="hlt">points</span> measured on existing ½ and 15-minute standard maps provide sufficient accuracy for any space imaging system thus far defined. This procedure references the <span class="hlt">points</span> to accepted horizontal and vertical datums. Maps as small as 1:250,000 scale can be used as source material for coordinates, but to maintain the desired accuracy, maps of 1:100,000 and larger scale should be used when available.</p> <div class="credits"> <p class="dwt_author">Burger, Thomas C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1973-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">350</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920051695&hterms=financial+considerations&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2522financial%2Bconsiderations%2522"> <span id="translatedtitle">Optimal actuator placement in adaptive <span class="hlt">precision</span> trusses</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Actuator placement in adaptive truss structures is to cater to two needs: displacement control of <span class="hlt">precision</span> <span class="hlt">points</span> and preloading the elements to overcome joint slackness. Due to technological and financial considerations, the number of actuators available is much less than the degrees of freedom of <span class="hlt">precision</span> <span class="hlt">points</span> to be controlled and the degree of redundancy of the structure. An approach for optimal actuator location is outlined. Test cases to demonstrate the effectiveness of the scheme are applied to the <span class="hlt">Precision</span> Segmented Reflector Truss.</p> <div class="credits"> <p class="dwt_author">Baycan, C. M.; Utku, S.; Das, S. K.; Wada, B. K.</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">351</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/270670"> <span id="translatedtitle"><span class="hlt">Precision</span> guided parachute LDRD final report</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This report summarizes the results of the <span class="hlt">Precision</span> Guided Parachute LDRD, a two year program at Sandia National Laboratories which developed a Global <span class="hlt">Positioning</span> System (GPS) guided parachute capable of autonomous flight and landings. A detailed computer model of a gliding parachute was developed for software only simulations. A hardware in-the-loop simulator was developed and used for flight package system integration and design validation. Initial parachute drop tests were conducted at Sandia`s Coyote Canyon Cable Facility, followed by a series of airdrops using Ross Aircraft`s Twin Otter at the Burris Ranch Drop Zone. Final flights demonstrated in-flight wind estimation and the capability to fly a commanded heading. In the past, the cost and logistical complexity of an initial navigation system ruled out actively guiding a parachute. The advent of the low-cost, light-weight Global <span class="hlt">Positioning</span> System (GPS) has eliminated this barrier. By using GPS <span class="hlt">position</span> and velocity measurements, a guided parachute can autonomously steer itself to a targeted <span class="hlt">point</span> on the ground through the use of control drums attached to the control lanyards of the parachute. By actively correcting for drop <span class="hlt">point</span> errors and wind drift, the guidance accuracy of this system should be on the order of GPS <span class="hlt">position</span> errors. This would be a significant improvement over unguided airdrops which may have errors of a mile or more.</p> <div class="credits"> <p class="dwt_author">Gilkey, J.C. [Sandia National Labs., Albuquerque, NM (United States). Aided Navigation and Remote Sensing Dept.</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">352</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AAS...21840604K"> <span id="translatedtitle">Fiber Scrambling for High <span class="hlt">Precision</span> Spectrographs</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The detection of Earth-like exoplanets with the radial velocity method requires extreme Doppler <span class="hlt">precision</span> and long-term stability in order to measure tiny reflex velocities in the host star. Recent planet searches have led to the detection of so called "super-Earths” (up to a few Earth masses) that induce radial velocity changes of about 1 m/s. However, the detection of true Earth analogs requires a <span class="hlt">precision</span> of 10 cm/s. One of the largest factors limiting Doppler <span class="hlt">precision</span> is variation in the <span class="hlt">Point</span> Spread Function (PSF) from observation to observation due to changes in the illumination of the slit and spectrograph optics. Thus, this stability has become a focus of current instrumentation work. Fiber optics have been used since the 1980's to couple telescopes to high-<span class="hlt">precision</span> spectrographs, initially for simpler mechanical design and control. However, fiber optics are also naturally efficient scramblers. Scrambling refers to a fiber's ability to produce an output beam independent of input. Our research is focused on characterizing the scrambling properties of several types of fibers, including circular, square and octagonal fibers. By measuring the intensity distribution after the fiber as a function of input beam <span class="hlt">position</span>, we can simulate guiding errors that occur at an observatory. Through this, we can determine which fibers produce the most uniform outputs for the severest guiding errors, improving the PSF and allowing sub-m/s <span class="hlt">precision</span>. However, extensive testing of fibers of supposedly identical core diameter, length and shape from the same manufacturer has revealed the "personality” of individual fibers. Personality describes differing intensity patterns for supposedly duplicate fibers illuminated identically. Here, we present our results on scrambling characterization as a function of fiber type, while studying individual fiber personality.</p> <div class="credits"> <p class="dwt_author">Kaplan, Zachary; Spronck, J. F. P.; Fischer, D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">353</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51061229"> <span id="translatedtitle">Minimum-energy <span class="hlt">point-to-point</span> trajectory planning of a simple mechatronic system</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In this paper, we propose a novel minimum-energy <span class="hlt">point-to-point</span> (PTP) trajectory planning method for a simple mechatronic system, which is a one-dimensional <span class="hlt">precision</span> <span class="hlt">positioning</span> table driven by a permanent magnet synchronous motor (PMSM). To generate the mechatronic trajectory we develop a real-coded genetic algorithm (RGA) to search for the optimal trajectory for the PTP motion. In this method, we design</p> <div class="credits"> <p class="dwt_author">Ming-Shyan Huang; Yi-Lung Hsu; Rong-Fong Fung</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">354</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23088631"> <span id="translatedtitle"><span class="hlt">Precise</span> determination of the absolute isotopic abundance ratio and the atomic weight of chlorine in three international reference materials by the <span class="hlt">positive</span> thermal ionization mass spectrometer-Cs2Cl+-graphite method.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Because the variation in chlorine isotopic abundances of naturally occurring chlorine bearing substances is significant, the IUPAC Inorganic Chemistry Division, Commission on Isotopic Abundances and Atomic Weights (CIAAW-IUPAC) decided that the uncertainty of atomic weight of chlorine (A(r)(Cl)) should be increased so that the implied range was related to terrestrial variability in 1999 (Coplen, T. B. Atomic weights of the elements 1999 (IUPAC Technical Report), Pure Appl. Chem.2001, 73(4), 667-683; and then, it emphasized that the standard atomic weights of ten elements including chlorine were not constants of nature but depend upon the physical, chemical, and nuclear history of the materials in 2009 (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396). According to the agreement by CIAAW that an atomic weight could be defined for one specified sample of terrestrial origin (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396), the absolute isotope ratios and atomic weight of chlorine in standard reference materials (NIST 975, NIST 975a, ISL 354) were accurately determined using the high-<span class="hlt">precision</span> <span class="hlt">positive</span> thermal ionization mass spectrometer (PTIMS)-Cs(2)Cl(+)-graphite method. After eliminating the weighing error caused from evaporation by designing a special weighing container and accurately determining the chlorine contents in two highly enriched Na(37)Cl and Na(35)Cl salts by the current constant coulometric titration, one series of gravimetric synthetic mixtures prepared from two highly enriched Na(37)Cl and Na(35)Cl salts was used to calibrate two thermal ionization mass spectrometers in two individual laboratories. The correction factors (i.e., K(37/35) = R(37/35meas)/R(37/35calc)) were obtained from five cycles of iterative calculations on the basis of calculated and determined R((37)Cl/(35)Cl) values in gravimetric synthetic mixtures. The absolute R((37)Cl/(35)Cl) ratios for NIST SRM 975, NIST 975a, and ISL 354 by the <span class="hlt">precise</span> calibrated isotopic composition measurements are 0.319876 ± 0.000067, 0.319768 ± 0.000187, and 0.319549 ± 0.000044, respectively. As a result, the atomic weights of chlorine in NIST 975, NIST 975a, and ISL 354 are derived as 35.45284(8), 35.45272(21), and 35.45252(2) individually, which are consistent with the issued values of 35.453(2) by IUPAC in 1999. PMID:23088631</p> <div class="credits"> <p class="dwt_author">Wei, Hai-Zhen; Jiang, Shao-Yong; Xiao, Ying-Kai; Wang, Jun; Lu, Hai; Wu, Bin; Wu, He-Pin; Li, Qing; Luo, Chong-Guang</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">355</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011JCMSI...4..199K"> <span id="translatedtitle">High-<span class="hlt">Precision</span> Motorcycle Trajectory Measurements Using GPS</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A method for measuring motorcycle trajectory using GPS is needed for simulating motorcycle dynamics. In GPS measurements of a motorcycle, both the declination of the motorcycle and obstacles near the course can cause problems. Therefore, we propose a new algorithm for GPS measurement of motorcycle trajectory. We interpolate the missing observation data within a few seconds using polynomial curves, and use a Kalman filter to smoothen <span class="hlt">position</span> calculations. This results in obtaining trajectory with high accuracy and with sufficient continuity. The <span class="hlt">precision</span> is equal to that of fixed <span class="hlt">point</span> <span class="hlt">positioning</span>, given a sufficient number of available satellites.</p> <div class="credits"> <p class="dwt_author">Koyama, Yuichiro; Tanaka, Toshiyuki</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">356</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3702919"> <span id="translatedtitle">Impact on ART initiation of <span class="hlt">point</span>-of-care CD4 testing at HIV diagnosis among HIV-<span class="hlt">positive</span> youth in Khayelitsha, South Africa</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Introduction Despite the rapid expansion of antiretroviral therapy (ART) programmes in developing countries, pre-treatment losses from care remain a challenge to improving access to treatment. Youth and adolescents have been identified as a particularly vulnerable group, at greater risk of loss from both pre-ART and ART care. <span class="hlt">Point</span>-of-care (POC) CD4 testing has shown promising results in improving linkage to ART care. In Khayelitsha township, South Africa, POC CD4 testing was implemented at a clinic designated for youth aged 12–25 years. We assessed whether there was an associated reduction in attrition between HIV testing, assessment for eligibility and ART initiation. Methods A before-and-after observational study was conducted using routinely collected data. These were collected on patients from May 2010 to April 2011 (Group A) when baseline CD4 count testing was performed in a laboratory and results were returned to the clinic within two weeks. Same-day POC CD4 testing was implemented in June 2011, and data were collected on patients from August 2011 to July 2012 (Group B). Results A total of 272 and 304 youth tested HIV-<span class="hlt">positive</span> in Group A and Group B, respectively. Group B patients were twice as likely to have their ART eligibility assessed compared to Group A patients: 275 (90%) vs. 183 (67%) [relative risk (RR)=2.4, 95% CI: 1.8–3.4, p<0.0001]. More patients in World Health Organization (WHO) Stage 1 disease (85% vs. 69%), with CD4 counts?350 cells/µL (58% vs. 35%) and more males (13% vs. 7%) were detected in Group B. The proportion of eligible patients who initiated ART was 50% and 44% (p=0.6) in Groups B and A, respectively; and 50% and 43% (p=0.5) when restricted to patients with baseline CD4 count?250 cells/µL. Time between HIV-testing and ART initiation was reduced from 36 to 28 days (p=0.6). Discussion POC CD4 testing significantly improved assessment for ART eligibility. The improvement in the proportion initiating ART and the reduction in time to initiation was not significant due to sample size limitations. Conclusions POC CD4 testing reduced attrition between HIV-testing and assessment of ART eligibility. Strategies to improve uptake of ART are needed, possibly by improving patient support for HIV-<span class="hlt">positive</span> youth immediately after diagnosis.</p> <div class="credits"> <p class="dwt_author">Patten, Gabriela EM; Wilkinson, Lynne; Conradie, Karien; Isaakidis, Petros; Harries, Anthony D; Edginton, Mary E; De Azevedo, Virginia; van Cutsem, Gilles</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">357</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24215119"> <span id="translatedtitle"><span class="hlt">Precision</span> of jaw-closing movements for different jaw gaps.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Jaw-closing movements are basic components of physiological motor actions <span class="hlt">precisely</span> achieving intercuspation without significant interference. The main purpose of this study was to test the hypothesis that, despite an imperfect intercuspal <span class="hlt">position</span>, the <span class="hlt">precision</span> of jaw-closing movements fluctuates within the range of physiological closing movements indispensable for meeting intercuspation without significant interference. For 35 healthy subjects, condylar and incisal <span class="hlt">point</span> <span class="hlt">positions</span> for fast and slow jaw-closing, interrupted at different jaw gaps by the use of frontal occlusal plateaus, were compared with uninterrupted physiological jaw closing, with identical jaw gaps, using a telemetric system for measuring jaw <span class="hlt">position</span>. Examiner-guided centric relation served as a clinically relevant reference <span class="hlt">position</span>. For jaw gaps ?4 mm, no significant horizontal or vertical displacement differences were observed for the incisal or condylar <span class="hlt">points</span> among physiological, fast, and slow jaw-closing. However, the jaw <span class="hlt">positions</span> under these three closing conditions differed significantly from guided centric relation for nearly all experimental jaw gaps. The findings provide evidence of stringent neuromuscular control of jaw-closing movements in the vicinity of intercuspation. These results might be of clinical relevance to occlusal intervention with different objectives. PMID:24215119</p> <div class="credits"> <p class="dwt_author">Hellmann, Daniel; Becker, Georg; Giannakopoulos, Nikolaos N; Eberhard, Lydia; Fingerhut, Christopher; Rammelsberg, Peter; Schindler, Hans J</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">358</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22303152"> <span id="translatedtitle">Use of terrestrial laser scanning technology for long term high <span class="hlt">precision</span> deformation monitoring.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The paper presents a new methodology for high <span class="hlt">precision</span> monitoring of deformations with a long term perspective using terrestrial laser scanning technology. In order to solve the problem of a stable reference system and to assure the high quality of possible <span class="hlt">position</span> changes of <span class="hlt">point</span> clouds, scanning is integrated with two complementary surveying techniques, i.e., high quality static GNSS <span class="hlt">positioning</span> and <span class="hlt">precise</span> tacheometry. The case study object where the proposed methodology was tested is a high pressure underground pipeline situated in an area which is geologically unstable. PMID:22303152</p> <div class="credits"> <p class="dwt_author">Vezo?nik, Rok; Ambroži?, Tomaž; Sterle, Oskar; Bilban, Gregor; Pfeifer, Norbert; Stopar, Bojan</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">359</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/42024129"> <span id="translatedtitle">Infiltration from a surface <span class="hlt">point</span> source and drip irrigation 2. An approximate time-dependent solution for wet-front <span class="hlt">position</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Raats' [1971] steady state theory is here extended to provide an approximate analysis of the transient pattern of wetting around a <span class="hlt">point</span> source. The assumption that a steady state regime prevails behind the wet front and the use of the Clothier [1984] and Philip [1984] theories on water movement along the streamlines allows an approximate transient solution for surface <span class="hlt">point</span></p> <div class="credits"> <p class="dwt_author">P. Revol; B. E. Clothier; J.-C. Mailhol; G. Vachaud; M. Vauclin</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">360</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19920013206&hterms=manufacturing+firms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmanufacturing%2Bfirms"> <span id="translatedtitle">Ultra-<span class="hlt">precision</span> processes for optics manufacturing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The Optics MODIL (Manufacturing Operations Development and Integration Laboratory) is developing advanced manufacturing technologies for fabrication of ultra <span class="hlt">precision</span> optical components, aiming for a ten-fold improvement in <span class="hlt">precision</span> and a shortening of the scheduled lead time. Current work focuses on diamond single <span class="hlt">point</span> turning, ductile grinding, ion milling, and in/on process metrology.</p> <div class="credits"> <p class="dwt_author">Martin, William R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_17");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a 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<div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_18");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a style="font-weight: bold;">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_20");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">361</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19870011801&hterms=microwave+resonance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmicrowave%2Bresonance"> <span id="translatedtitle"><span class="hlt">Precision</span> tunable resonant microwave cavity</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A tunable microwave cavity containing ionizable metallic vapor or gases and an apparatus for <span class="hlt">precisely</span> <span class="hlt">positioning</span> a microwave coupling tip in the cavity and for <span class="hlt">precisely</span> adjusting at least one dimension of the cavity are disclosed. With this combined structure, resonance may be achieved with various types of ionizable gases. A coaxial probe extends into a microwave cavity through a tube. One end of the tube is retained in a spherical joint attached in the cavity wall. This allows the coaxial probe to be pivotally rotated. The coaxial probe is slideable within the tube thus allowing the probe to be extended toward or retracted from the center of the cavity.</p> <div class="credits"> <p class="dwt_author">Nakanishi, Shigeo (inventor); Calco, Frank S. (inventor); Scarpelli, August R. (inventor)</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">362</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19840033164&hterms=Manufacturing+gear&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DManufacturing%2Bgear"> <span id="translatedtitle">Kinematic <span class="hlt">precision</span> of gear trains</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Kinematic <span class="hlt">precision</span> is affected by errors which are the result of either intentional adjustments or accidental defects in manufacturing and assembly of gear trains. A method for the determination of kinematic <span class="hlt">precision</span> of gear trains is described. The method is based on the exact kinematic relations for the contact <span class="hlt">point</span> motions of the gear tooth surfaces under the influence of errors. An approximate method is also explained. Example applications of the general approximate methods are demonstrated for gear trains consisting of involute (spur and helical) gears, circular arc (Wildhaber-Novikov) gears, and spiral bevel gears. Gear noise measurements from a helicopter transmission are presented and discussed with relation to the kinematic <span class="hlt">precision</span> theory. Previously announced in STAR as N82-32733</p> <div class="credits"> <p class="dwt_author">Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">363</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3334767"> <span id="translatedtitle">Transpulmonary thermodilution assessments: <span class="hlt">precise</span> measurements require a <span class="hlt">precise</span> procedure</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">When incorporating the values of a hemodynamic parameter into the care of patients, the <span class="hlt">precision</span> of the measurement method should always be considered. A prospective analysis in the previous issue of Critical Care showed that the <span class="hlt">precision</span> of transpulmonary thermodilution (TPTD) allows for reliable mean values if a standardised procedure is used. The present finding has a physiological basis, as TPTD requires a more prolonged transit time, which in turn reduces the effects that airway pressure and arrhythmia have on venous return-cardiac output steady states. Moreover, this result suggests that the current accepted threshold value of a 15% increase in cardiac output to identify a <span class="hlt">positive</span> response to a fluid challenge could be reduced in the future. Indeed, this value is mainly related to the <span class="hlt">precision</span> of the pulmonary artery catheter.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">364</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=N9111995"> <span id="translatedtitle">Range Resolution of <span class="hlt">Point</span> Targets with FMCW Radar Systems.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The spectral analysis of the low pass filtered echo signals of a stationary <span class="hlt">point</span> target was carried out starting with the <span class="hlt">precise</span> <span class="hlt">position</span> of the transmit signal of a Frequency Modulated Continuous-Wave (FMCW) radar operated with sawtooth modulation and ...</p> <div class="credits"> <p class="dwt_author">R. Hammel</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">365</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.navlab.net/Publications/Sigma_Point_Kalman_Filter_For_Underwater_Terrain-Based_Navigation.pdf"> <span id="translatedtitle">SIGMA <span class="hlt">POINT</span> KALMAN FILTER FOR UNDERWATER TERRAIN-BASED NAVIGATION</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Precise</span> underwater navigation is crucial in a number of marine applications. Navigation of most autonomous underwater vehicles (AUVs) is based on inertial navi- gation. Such navigation systems drift off with time and external fixes are needed. This paper concentrates on terrain-based navigation, where <span class="hlt">position</span> fixes are found by com- paring measurements with a prior map. Nonlinear Bayesian methods like <span class="hlt">point</span></p> <div class="credits"> <p class="dwt_author">Kjetil Bergh Ånonsen; Oddvar Hallingstad</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">366</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/6751700"> <span id="translatedtitle"><span class="hlt">Precision</span> zero-home locator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A zero-home locator includes a fixed phototransistor switch and a moveable actuator including two symmetrical, opposed wedges, each wedge defining a <span class="hlt">point</span> at which switching occurs. The zero-home location is the average of the <span class="hlt">positions</span> of the <span class="hlt">points</span> defined by the wedges.</p> <div class="credits"> <p class="dwt_author">Stone, W.J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-10-31</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">367</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850007869&hterms=truckenbrodt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2522truckenbrodt%2522"> <span id="translatedtitle"><span class="hlt">Precise</span> control of flexible manipulators</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The design and experimental testing of end <span class="hlt">point</span> <span class="hlt">position</span> controllers for a very flexible one link lightweight manipulator are summarized. The latest upgraded version of the experimental set up, and the basic differences between conventional joint angle feedback and end <span class="hlt">point</span> <span class="hlt">position</span> feedback are described. A general procedure for application of modern control methods to the problem is outlined. The relationship between weighting parameters and the bandwidth and control stiffness of the resulting end <span class="hlt">point</span> <span class="hlt">position</span> closed loop system is shown. It is found that joint rate angle feedback in addition to the primary end <span class="hlt">point</span> <span class="hlt">position</span> sensor is essential for adequate disturbance rejection capability of the closed loop system. The use of a low order multivariable compensator design computer code; called Sandy is documented. A solution to the problem of control mode switching between <span class="hlt">position</span> sensor sets is outlined. The proof of concept for endpoint <span class="hlt">position</span> feedback for a one link flexible manipulator was demonstrated. The bandwidth obtained with the experimental end <span class="hlt">point</span> <span class="hlt">position</span> controller is about twice as fast as the beam's first natural cantilevered frequency, and comes within a factor of four of the absolute physical speed limit imposed by the wave propagation time of the beam.</p> <div class="credits"> <p class="dwt_author">Cannon, R. H., Jr.; Bindford, T. O.; Schmitz, E.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">368</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20080004430&hterms=BROOKS+John&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2522BROOKS%252C%2BJohn%2522"> <span id="translatedtitle">High-accuracy discrete <span class="hlt">positioning</span> device</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">An article (30) is controllably and <span class="hlt">precisely</span> <span class="hlt">positioned</span> at one of three discrete locations defined by a linkage. The <span class="hlt">positioning</span> apparatus includes two independently driven cranks (34, 42), with a link (50) pivotably connected between the two cranks (34, 42). Another connector (44) is pivotably connected between one of the cranks (34 or 42) and the article (30) to be <span class="hlt">positioned</span>. The cranks (34, 42) are rotationally adjusted so that the pivot <span class="hlt">points</span> (52, 54) of the link (50) are collinear with the axes of rotation of the cranks (40, 48), thereby defining one of the three discrete locations. Additional cranks and links can be provided to define additional discrete locations.</p> <div class="credits"> <p class="dwt_author">Brooks, John J. (Inventor)</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">369</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51021007"> <span id="translatedtitle">Simulation of <span class="hlt">Precise</span> Offline Satellite Orbit Determination</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In this paper we have taken advantages of <span class="hlt">precise</span> orbit determination of satellite trajectories using offline simulations. Furthermore perturbation forces which make complex motion equations of satellites and cause more complicated satellites trajectories are simulated using Poisson and Lagrange brackets methods. Moreover perturbation forces effects in the satellites motion are investigated and <span class="hlt">precise</span> <span class="hlt">position</span> of satellite is estimated. Finally a</p> <div class="credits"> <p class="dwt_author">Mohammad Bagher Alaee; Hossein Rahmani</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">370</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://bloodjournal.hematologylibrary.org/cgi/reprint/99/9/3472.pdf"> <span id="translatedtitle">High frequency of <span class="hlt">point</span> mutations clustered within the adenosine triphosphate-binding region of BCR\\/ABL in patients with chronic myeloid leukemia or Ph-<span class="hlt">positive</span> acute lymphoblastic leukemia who develop imatinib (STI571) resistance</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Point</span> mutations were found in the adeno- sine triphosphate (ATP) binding region of BCR\\/ABL in 12 of 18 patients with chronic myeloid leukemia (CML) or Ph-<span class="hlt">positive</span> acute lymphoblastic leukemia (Ph ALL) and imatinib resistance (defined as loss of established hematologic response), but they were found in only 1 of 10 patients with CML with imatinib refractoriness (fail- ure to achieve</p> <div class="credits"> <p class="dwt_author">Susan Branford; Zbigniew Rudzki; Sonya Walsh; Andrew Grigg; Chris Arthur; Kerry Taylor; Richard Herrmann; Kevin P. Lynch; Timothy P. Hughes</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">371</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA291091"> <span id="translatedtitle"><span class="hlt">Precision</span> Speed Reducer for Robotics and Manufacturing.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The robotics and manufacturing industries rely on high <span class="hlt">precision</span> speed reducers to convert low motor torques to high output torque without degrading the tool <span class="hlt">position</span>. SYNKINETICS Inc. has developed a new and innovative technology that uses flat plate cam...</p> <div class="credits"> <p class="dwt_author">F. Folino S. Schechter J. Quigley J. Maslow</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">372</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1997WRR....33.1869R"> <span id="translatedtitle">Infiltration from a surface <span class="hlt">point</span> source and drip irrigation: 2. An approximate time-dependent solution for wet-front <span class="hlt">position</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Raats' [1971] steady state theory is here extended to provide an approximate analysis of the transient pattern of wetting around a <span class="hlt">point</span> source. The assumption that a steady state regime prevails behind the wet front and the use of the Clothier [1984] and Philip [1984] theories on water movement along the streamlines allows an approximate transient solution for surface <span class="hlt">point</span> source infiltration to be developed. This procedure was previously tested against absorption theory and laboratory experiments [Revol et al., 1995], but now this new analysis is evaluated via a field test. The vertical elongating influence of gravity is found to be well predicted. Application of this analysis to design purposes is also mentioned. The role of the macroscopic characteristic capillary length of unsaturated flow, ?c, is highlighted by this approximate solution. Finally, we propose a method that allows estimation of ?c from a <span class="hlt">point</span>-source infiltration experiment.</p> <div class="credits"> <p class="dwt_author">Revol, P.; Clothier, B. E.; Mailhol, J.-C.; Vachaud, G.; Vauclin, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">373</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=dressing&pg=3&id=EJ877113"> <span id="translatedtitle"><span class="hlt">Positive</span> Changes in Perceptions and Selections of Healthful Foods by College Students after a Short-Term <span class="hlt">Point</span>-of-Selection Intervention at a Dining Hall</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">Objective: Determine the effects of a short-term, multi-faceted, <span class="hlt">point</span>-of-selection intervention on college students' perceptions and selection of 10 targeted healthful foods in a university dining hall and changes in their self-reported overall eating behaviors. Participants: 104 college students, (age 18-23) completed pre-I and post-I surveys.…</p> <div class="credits"> <p class="dwt_author">Peterson, Sharon; Duncan, Diana Poovey; Null, Dawn Bloyd; Roth, Sara Long; Gill, Lynn</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">374</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003PASJ...55..553Y"> <span id="translatedtitle">High-<span class="hlt">Precision</span> Radiant Analysis of the 2001 Leonids Using Telescopic Optics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We employed a new line-detection method and tried to separate two radiant <span class="hlt">points</span> corresponding to the dust trails of Comet 55P/Tempel-Tuttle's perihelion passages in 1699 and 1866. This method integrates the pixel values of a CCD image along a line direction, which enables us to detect 30-times fainter meteors than when using the usual detection methods. It can also <span class="hlt">precisely</span> determine the angle of the line direction. Two telescopic optics equipped with cooled CCD cameras were <span class="hlt">pointed</span> to regions that make a right angle with the radiant <span class="hlt">points</span> in order to <span class="hlt">precisely</span> determine their <span class="hlt">positions</span>. Radiant <span class="hlt">points</span> of the 2001 Leonids derived by this method were found to be consistent with those predicted by McNaught and Asher.</p> <div class="credits"> <p class="dwt_author">Yanagisawa, Toshifumi; Ohnishi, Kouji; Torii, Ken'ichi; Kohama, Mitsuhiro; Nakajima, Atsushi; Asher, David</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">375</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013ApPhB.111..141N"> <span id="translatedtitle">Novel method for laser focal <span class="hlt">point</span> <span class="hlt">positioning</span> on the cover slip for TPP-based microfabrication and detection of the cured structure under optical microscope</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Detection of a single cured structure in two-photon photopolymerization (TPP) based microstructure fabrication requires the laser focal spot to be exactly <span class="hlt">positioned</span> on the cover slip. This is due to the fact that if the laser focal <span class="hlt">position</span> is not exactly on the cover slip, the structure may not stick to the cover slip and flow away with the liquid during the washing and developing stages. In this paper, we report a scheme of laser spot <span class="hlt">positioning</span> for the implementation of TPP process and the detection of a single cured microstructure under an optical microscope. For this, a novel yet very simple approach is devised and an uncomplicated procedure is developed. Experimental results are also included to prove the worthiness of the devised method.</p> <div class="credits"> <p class="dwt_author">Najam, Muhammad Tallal Bin; Arif, Khalid Mahmood; Lee, Yong-Gu</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">376</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003AGUFM.C32A0430R"> <span id="translatedtitle">ICESat <span class="hlt">Precision</span> Orbit Determination</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Following the successful launch of the Ice, Cloud and land Elevation Satellite (ICESat) on January 13, 2003, 00:45 UTC, the GPS receiver on ICESat was turned on successfully on Jan. 17, 2003. High quality GPS data were collected since then to support <span class="hlt">Precision</span> Orbit Determination (POD) activities. ICESat carries Geoscience Laser Altimeter System (GLAS) to measure ice-sheet topography and associated temporal changes, as well as cloud and atmospheric properties. To accomplish the ICESat science objectives, the <span class="hlt">position</span> of the GLAS instrument in space should be determined with an accuracy of 5 cm and 20 cm in radial and horizontal components, respectively. This knowledge is acquired by the POD activities using the data collected by the GPS receiver on ICESat and the ground-based satellite laser ranging (SLR) data. It has been shown from pre-launch POD studies that the gravity model error is the dominant source of ICESat orbit errors. The predicted radial orbit errors at the ICESat orbit (600 km altitude) based on pre-launch gravity models, such as TEG-4 and EGM-96, are 7-15 cm. Performance of these gravity models and the recent gravity models from GRACE on ICESat POD were evaluated. The radial orbit accuracy is approaching 1-2 cm level with the GRACE gravity model. This paper also summarizes POD activities at Center for Space Research (CSR), which is responsible to generate ICESat POD products.</p> <div class="credits"> <p class="dwt_author">Rim, H.; Yoon, S.; Webb, C. E.; Kim, Y.; Schutz, B. E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">377</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013Ap%26SS.346...71H"> <span id="translatedtitle"><span class="hlt">Position</span> and velocity sensitivities at the triangular libration <span class="hlt">points</span> in the restricted problem of three bodies when the bigger primary is an oblate body</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In this paper we have examined the stability of triangular libration <span class="hlt">points</span> in the restricted problem of three bodies when the bigger primary is an oblate spheroid. Here we followed the time limit and computational process of Tuckness (Celest. Mech. Dyn. Mech. 61, 1-19, 1995) on the stability criteria given by McKenzie and Szebehely (Celest. Mech. 23, 223-229, 1981). In this study it was found that in comparison to other studies the value of the critical mass ? c has been reduced due to oblateness of the bigger primary, i.e. the range of stability of the equilateral triangular libration <span class="hlt">points</span> reduced with the increase of the oblateness parameter I and hence the order of commensurability was increased.</p> <div class="credits"> <p class="dwt_author">Hassan, M. R.; Antia, H. M.; Bhatnagar, K. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">378</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24400888"> <span id="translatedtitle">Enhanced resistive switching phenomena using low-<span class="hlt">positive</span>-voltage format and self-compliance IrOx/GdOx/W cross-<span class="hlt">point</span> memories.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Enhanced resistive switching phenomena of IrOx/GdOx/W cross-<span class="hlt">point</span> memory devices have been observed as compared to the via-hole devices. The as-deposited Gd2O3 films with a thickness of approximately 15 nm show polycrystalline that is observed using high-resolution transmission electron microscope. Via-hole memory device shows bipolar resistive switching phenomena with a large formation voltage of -6.4 V and high operation current of >1 mA, while the cross-<span class="hlt">point</span> memory device shows also bipolar resistive switching with low-voltage format of +2 V and self-compliance operation current of <300 ?A. Switching mechanism is based on the formation and rupture of conducting filament at the IrOx/GdOx interface, owing to oxygen ion migration. The oxygen-rich GdOx layer formation at the IrOx/GdOx interface will also help control the resistive switching characteristics. This cross-<span class="hlt">point</span> memory device has also Repeatable 100 DC switching cycles, narrow distribution of LRS/HRS, excellent pulse endurance of >10,000 in every cycle, and good data retention of >104 s. This memory device has great potential for future nanoscale high-density non-volatile memory applications. PMID:24400888</p> <div class="credits"> <p class="dwt_author">Jana, Debanjan; Maikap, Siddheswar; Prakash, Amit; Chen, Yi-Yan; Chiu, Hsien-Chin; Yang, Jer-Ren</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">379</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=https://www.fig.net/pub/athens/papers/wsa2/wsa2_5_balis_et_al.pdf"> <span id="translatedtitle">3D - Laser Scanning: Integration of <span class="hlt">Point</span> Cloud and CCD Camera Video Data for the Production of High Resolution and <span class="hlt">Precision</span> RGB Textured Models: Archaeological Monuments Surveying Application in Ancient Ilida</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">SUMMARY In this project, techniques of integration of 3D - Laser Scanning <span class="hlt">point</span> cloud data and the video produced by the CCD camera are explored. This integration is employed to the produc- tion of high - accuracy and resolution RGB textured models and ortho - photo diagrams of archaeological monuments. The \\</p> <div class="credits"> <p class="dwt_author">Vaios BALIS; Spyros KARAMITSOS; Ioannis KOTSIS; Christos LIAPAKIS</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">380</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/7129157"> <span id="translatedtitle"><span class="hlt">Positioning</span> apparatus</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">An apparatus is provided for <span class="hlt">precisely</span> adjusting the <span class="hlt">position</span> of an article relative to a beam emerging from a neutron source disposed in a housing. The apparatus includes a support pivotably mounted on a movable base plate and freely suspended therefrom. The support is gravity biased toward the housing and carries an article holder movable in a first direction longitudinally of the axis of said beam and normally urged into engagement against said housing. Means are provided for moving the base plate in two directions to effect movement of the suspended holder in two mutually perpendicular directions, respectively, normal to the axis of the beam.</p> <div class="credits"> <p class="dwt_author">Vogel, M.A.; Alter, P.</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-07-07</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_18");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" 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showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_21");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">381</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/875231"> <span id="translatedtitle"><span class="hlt">Positioning</span> apparatus</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">An apparatus for <span class="hlt">precisely</span> <span class="hlt">positioning</span> materials test specimens within the optimum neutron flux path emerging from a neutron source located in a housing. The test specimens are retained in a holder mounted on the free end of a support pivotably mounted and suspended from a movable base plate. The support is gravity biased to urge the holder in a direction longitudinally of the flux path against the housing. Means are provided for moving the base plate in two directions to effect movement of the holder in two mutually perpendicular directions normal to the axis of the flux path.</p> <div class="credits"> <p class="dwt_author">Vogel, Max A. (Kennewick, WA); Alter, Paul (Richland, WA)</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">382</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53488854"> <span id="translatedtitle">Orbit determination and European station <span class="hlt">positioning</span> from satellite laser ranging</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A fundamental objective of the use of space geodetic techniques is related to the accurate spatial <span class="hlt">positioning</span> of terrestrial <span class="hlt">points</span> in a regional to global context. The results have a wide scope of applications, extending from general surveying to the monitoring of crustal movements. The most <span class="hlt">precise</span> technique for station-to-satellite relative <span class="hlt">positioning</span> involves ground-based laser ranging to artificial satellites. During</p> <div class="credits"> <p class="dwt_author">K. F. Wakker; B. A. C. Ambrosius; L. Aardoom</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">383</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=optics+AND+laser+AND+technology&pg=3&id=ED285009"> <span id="translatedtitle"><span class="hlt">Precision</span> Optics Curriculum.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">This guide outlines the competency-based, two-year <span class="hlt">precision</span> optics curriculum that the American <span class="hlt">Precision</span> Optics Manufacturers Association has proposed to fill the void that it suggests will soon exist as many of the master opticians currently employed retire. The model, which closely resembles the old European apprenticeship model, calls for 300…</p> <div class="credits"> <p class="dwt_author">Reid, Robert L.; And Others</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">384</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012SPIE.8417E..2HS"> <span id="translatedtitle">High <span class="hlt">precision</span> calibration for 2D optical standard</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Photomask is a kind of 2-D optical standard with etched orthogonal coordinates made of a glass substrate chrominged or filmed with other metal. In order to solve the problems of measurement and traceability of ultra <span class="hlt">precision</span> photomasks used in advanced manufacturing industry, 2-D photomask optical standard was calibrated in high <span class="hlt">precision</span> laser two coordinate standard device. A high <span class="hlt">precision</span> differential laser interferometer system was used for a length standard, a high magnification optical micro vision system was used for <span class="hlt">precision</span> optical <span class="hlt">positioning</span> feedback. In this paper, a image measurement model was purposed; A sampling window auto identification algorithm was designed. Grid stripe image could be identified and aimed at automatically by this algorithm. An edge detection method based on bidirection progressive scanning and 3-sigma rule for eliminating outliers in sampling window was found. Dirty <span class="hlt">point</span> could be removed with effect. Edge detection error could be lowered. By this means, the measurement uncertainty of 2-D optical standard's ruling span was less than 0.3 micrometer (k=2).</p> <div class="credits"> <p class="dwt_author">Sun, Shuanghua; Gan, Xiaochuan; Xue, Zi; Ye, Xiaoyou; Wang, Heyan; Gao, Hongtang</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">385</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009JASS...26...89K"> <span id="translatedtitle">Validation of GPS Based <span class="hlt">Precise</span> Orbits Using SLR Observations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In this study, the YLPODS (Yonsei Laser-ranging <span class="hlt">Precision</span> Orbit Determination System) is developed for POD using SLR (Satellite Laser Ranging) NP (Normal <span class="hlt">Point</span>) observations. The performance of YLPODS is tested using SLR NP observations of TOPEX/POSEIDON and CHAMP satellite. JPL's POE (<span class="hlt">Precision</span> Orbit Ephemeris) is assumed to be true orbit, the measurement residual RMS (Root Mean Square) and the orbit accuracy (radial, along-track, cross-track) are investigated. The validation of POD using GPS (Global <span class="hlt">Positioning</span> System) raw data is achieved by YLPODS performance and highly accurate SLR NP observations. YGPODS (Yonsei GPS-based <span class="hlt">Precision</span> Orbit Determination System) is used for generating GPS based <span class="hlt">precise</span> orbits for TOPEX/POSEIDON. The initial orbit for YLPODS is derived from the YGPODS results. To validate the YGPODS results the range residual of the first adjustment of YLPODS is investigated. The YLPODS results using SLR NP observations of TOPEX/POSEIDON and CHAMP satellite show that the range residual is less than 10 cm and the orbit accuracy is about 1 m level. The validation results of the YGPODS orbits using SLR NP observations of the TOPEX/POSEIDON satellite show that the range residual is less than 10 cm. This result predicts that the accuracy of this GPS based orbits is about 1m level and it is compared with JPL's POE. Thus this result presents that the YLPODS can be used for POD validation using SLR NP observations such as STSAT-2 and KOMPSAT-5.</p> <div class="credits"> <p class="dwt_author">Kim, Young-Rok; Park, Eunseo; Park, Sang-Young; Choi, Kyu-Hong; Hwang, Yoola; Kim, Hae-Yeon; Lee, Byoung-Sun; Kim, Jaehoon</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">386</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004AGUFM.P23A0222H"> <span id="translatedtitle">Low Cost <span class="hlt">Precision</span> Lander for Lunar Exploration</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">For 60 years the US Defense Department has invested heavily in producing small, low mass, <span class="hlt">precision</span> guided vehicles. The technologies matured under these programs include terrain-aided navigation, closed loop terminal guidance algorithms, robust autopilots, high thrust-to-weight propulsion, autonomous mission management software, sensors, and data fusion. These technologies will aid NASA in addressing New Millennium Science and Technology goals as well as the requirements flowing from the Vision articulated in January 2004. Establishing and resupplying a long term lunar presence will require automated landing <span class="hlt">precision</span> not yet demonstrated. <span class="hlt">Precision</span> landing will increase safety and assure mission success. In the DOD world, such technologies are used routinely and reliably. Hence, it is timely to generate a <span class="hlt">point</span> design for a <span class="hlt">precise</span> planetary lander useful for lunar exploration. In this design science instruments amount to 10 kg, 16% of the lander vehicle mass. This compares favorably with 7% for Mars Pathfinder and less than 15% for Surveyor. The mission design flies the lander in an inert configuration to the moon, relying on a cruise stage for navigation and TCMs. The lander activates about a minute before impact. A solid booster reduces the vehicle speed to 300-450 m/s. The lander is now about 2 minutes from touchdown and has 600 to 700 m/s delta-v capability, allowing for about 10 km of vehicle divert during terminal descent. This concept of operations is chosen because it closely mimics missile operational timelines used for decades: the vehicle remains inert in a challenging environment, then must execute its mission flawlessly on a moment's notice. The vehicle design consists of a re-plumbed propulsion system, using propellant tanks and thrusters from exoatmospheric programs. A redesigned truss provides hard <span class="hlt">points</span> for landing gear, electronics, power supply, and science instruments. A radar altimeter and a Digital Scene Matching Area Correlator (DSMAC) provide data for the terminal guidance algorithms. DSMAC acquires high-resolution images for real-time correlation with a reference map. This system provides ownship <span class="hlt">position</span> with a resolution comparable to the map. Since the DSMAC can sample at 1.5 mrad, any imaging acquired below 70 km altitude will surpass the resolution available from previous missions. DSMAC has a mode where image data are compressed and downlinked. This capability could be used to downlink live images during terminal guidance. Approximately 500 kbitps telemetry would be required to provide the first live descent imaging sequence since Ranger. This would provide unique geologic context imaging for the landing site. The development path to produce such a vehicle is that used to develop missiles. First, a pathfinder vehicle is designed and built as a test bed for hardware integration including science instruments. Second, a hover test vehicle would be built. Equipped with mass mockups for the science payload, the vehicle would otherwise be an exact copy of the flight vehicle. The hover vehicle would be flown on earth to demonstrate the proper function and integration of the propulsion system, autopilots, navigation algorithms, and guidance sensors. There is sufficient delta-v in the proposed design to take off from the ground, fly a ballistic arc to over 100 m altitude, then guide to a <span class="hlt">precision</span> soft landing. Once the vehicle has flown safely on earth, then the validated design would be used to produce the flight vehicle. Since this leverages the billions of dollars DOD has invested in these technologies, it should be possible to land useful science payloads <span class="hlt">precisely</span> on the lunar surface at relatively low cost.</p> <div class="credits"> <p class="dwt_author">Head, J. N.; Gardner, T. G.; Hoppa, G. V.; Seybold, K. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">387</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/12599843"> <span id="translatedtitle">Testing Complete <span class="hlt">Positivity</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We study the modified dynamical evolution of the neutral kaon system under the condition of complete <span class="hlt">positivity</span>. The accuracy of the data from planned future experiments is expected to be sufficiently <span class="hlt">precise</span> to test such a hypothesis.</p> <div class="credits"> <p class="dwt_author">Fabio Benatti; Roberto Floreanini</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">388</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20110016379&hterms=cleanroom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcleanroom"> <span id="translatedtitle"><span class="hlt">Precision</span> Cryogenic Dilatometer</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A dilatometer based on a laser interferometer is being developed to measure mechanical creep and coefficients of thermal expansion (CTEs) of materials at temperatures ranging from ambient down to 15 K. This cryogenic dilatometer has been designed to minimize systematic errors that limit the best previously available dilatometers. At its prototype stage of development, this cryogenic dilatometer yields a strain measurement error of 35 ppb or 1.7 ppb/K CTE measurement error for a 20-K thermal load, for low-expansion materials in the temperature range from 310 down to 30 K. Planned further design refinements that include a provision for stabilization of the laser and addition of a high-<span class="hlt">precision</span> sample-holding jig are expected to reduce the measurement error to 5-ppb strain error or 0.3-ppb/K CTE error for a 20-K thermal load. The dilatometer (see figure) includes a common-path, differential, heterodyne interferometer; a dual-frequency, stabilized source bench that serves as the light source for the interferometer; a cryogenic chamber in which one places the material sample to be studied; a cryogenic system for cooling the interior of the chamber to the measurement temperature; an ultra-stable alignment stage for <span class="hlt">positioning</span> the chamber so that the sample is properly <span class="hlt">positioned</span> with respect to the interferometer; and a data-acquisition and control system. The cryogenic chamber and the interferometer portion of the dilatometer are housed in a vacuum chamber on top of a vibration isolating optical table in a cleanroom. The sample consists of two pieces a pillar on a base both made of the same material. Using reflections of the interferometer beams from the base and the top of the pillar, what is measured is the change in length of the pillar as the temperature in the chamber is changed. In their fundamental optical and electronic principles of operation, the laser light source and the interferometer are similar to those described in Common-Path Heterodyne Interferometers (NPO-20786), NASA Tech Briefs, Vol. 25, No. 7 (July 2001), page 12a, and Interferometer for Measuring Displacement to Within 20 pm (NPO- 21221), NASA Tech Briefs, Vol. 27, No. 7 (July 2003), page 8a. However, the present designs incorporate a number of special geometric, optical, and mechanical features to minimize optical and thermal-expansion effects that contribute to measurement errors. These features include the use of low-thermal expansion materials for structural components, kinematic mounting and symmetrical placement of optical components, and several measures taken to minimize spurious reflections of laser beams.</p> <div class="credits"> <p class="dwt_author">Dudik, Matthew; Halverson, Peter; Levine-West, Marie; Marcin, Martin; Peters, Robert D.; Shaklan, Stuart</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">389</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/2388389"> <span id="translatedtitle">Accelerating double <span class="hlt">precision</span> FEM simulations with GPUs</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Abstract In visualization and computer,graphics it has been shown,that the numerical solution of PDE problems can be obtained much,faster on graphics processors (GPUs) than on CPUs. However, GPUs are restricted to single <span class="hlt">precision</span> floating <span class="hlt">point</span> arithmetics which is insufficient for most technical scientific computations. Since we do not expect double <span class="hlt">precision</span> support natively in graphics hardware in the medium-term, we</p> <div class="credits"> <p class="dwt_author">R. Strzodka; S. Ture</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">390</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850000250&hterms=electrochemical+machining&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Delectrochemical%2Bmachining"> <span id="translatedtitle"><span class="hlt">Precise</span> Electrochemical Drilling of Repeated Deep Holes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Tooling enables maintenance of close tolerances. Tooling includes guide that holds electrochemical drilling electrodes in proper relative alinement and guide-<span class="hlt">positioning</span> fixture clamps directly on reference surfaces of strut. High <span class="hlt">precision</span> achieved by <span class="hlt">positioning</span> tooling anew on each strut before drilling: Tolerances of (0.008 mm) maintained in some details.</p> <div class="credits"> <p class="dwt_author">Kincheloe, J. P.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">391</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51133774"> <span id="translatedtitle">Geospatial Data Fusion for <span class="hlt">Precision</span> Agriculture</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Geospatial science, a genetic term that includes Global Navigation Satellite Systems (GNSS), Geographical Information System (GIS) and Remote Sensing (RS), are playing essential roles in food security through using <span class="hlt">Precision</span> Agriculture (PA) technologies. For instance, real-time kinematic GPS <span class="hlt">positioning</span>, as an enabling <span class="hlt">positioning</span> technology for PA, has already delivered net benefits that meet both food security and sustainability criteria. However,</p> <div class="credits"> <p class="dwt_author">Xiaolin Meng; Alan Dodson; Jixian Zhang; Yanhui Cai; Chun Liu; Keith Geary</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">392</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23529116"> <span id="translatedtitle">Experimental study on the <span class="hlt">precise</span> orbit determination of the BeiDou navigation satellite system.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The regional service of the Chinese BeiDou satellite navigation system is now in operation with a constellation including five Geostationary Earth Orbit satellites (GEO), five Inclined Geosynchronous Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. Besides the standard <span class="hlt">positioning</span> service with <span class="hlt">positioning</span> accuracy of about 10 m, both <span class="hlt">precise</span> relative <span class="hlt">positioning</span> and <span class="hlt">precise</span> <span class="hlt">point</span> <span class="hlt">positioning</span> are already demonstrated. As is well known, <span class="hlt">precise</span> orbit and clock determination is essential in enhancing <span class="hlt">precise</span> <span class="hlt">positioning</span> services. To improve the satellite orbits of the BeiDou regional system, we concentrate on the impact of the tracking geometry and the involvement of MEOs, and on the effect of integer ambiguity resolution as well. About seven weeks of data collected at the BeiDou Experimental Test Service (BETS) network is employed in this experimental study. Several tracking scenarios are defined, various processing schemata are designed and carried out; and then, the estimates are compared and analyzed in detail. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. The involvement of MEOs and ambiguity-fixing also make the orbits better. PMID:23529116</p> <div class="credits"> <p class="dwt_author">He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">393</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19990009655&hterms=PSR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2522PSR%2522"> <span id="translatedtitle"><span class="hlt">Precision</span> Segmented Reflectors (PSR)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Current <span class="hlt">Precision</span> Segmented Reflectors (PSR) technology development is intended for LDR-like applications: (1) Large segmented reflector systems; (2) Lightweight composite panels at 3 micron root-mean-square (RMS); (3) <span class="hlt">Precision</span> lightweight structure at 500 microns; (4) Active figure control at 1 micron RMS accuracy; and (5) 5 micron RMS overall surface accuracy. Development of PSR technologies to date has demonstrated the potential of: (1) Lightweight composite panels at 0.1 micron RMS via polishing and re-finishing; (2) Shape control of composite panels by imbedded actuators; (3) <span class="hlt">Precision</span> lightweight structure at 100 microns or better; and (4) Smart structure strut that can suppress vibrations and change its length.</p> <div class="credits"> <p class="dwt_author">Lin, Richard Y.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">394</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011SPIE.8191E..72Z"> <span id="translatedtitle">Research on <span class="hlt">pointing</span> of piezoelectric fast steering mirror under vibration condition</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Piezoelectric Fast Steering Mirror (PFSM) is widely used to realize fast and <span class="hlt">precise</span> <span class="hlt">pointing</span> in optical systems. To eliminate the nonlinearity, close-loop driving circuit must be used through <span class="hlt">position</span> sensors such as strain gauge. Since PFSM not only works in static condition, but also needs <span class="hlt">pointing</span> <span class="hlt">precisely</span> under dynamic condition, it is necessary to research the <span class="hlt">pointing</span> performance under shock and random vibration. The platform was established and the experiment was done to verify the deviation angle of PFSM during vibration in this paper. The conclusion is got finally.</p> <div class="credits"> <p class="dwt_author">Zhang, Bingna; Zhang, Liang; Huang, Genghua; Shu, Rong</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">395</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=AD605528"> <span id="translatedtitle">Brushless <span class="hlt">Precision</span> Potentiometer.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The purpose of the program is to perform studies leading to the fabrication of eight brushless <span class="hlt">precision</span> potentiometers. A detailed description of the preparation of cadmium sulphide photoswitches and results of preliminary tests to determine proper sensi...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1964-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">396</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/FR-2012-01-11/pdf/2012-307.pdf"> <span id="translatedtitle">77 FR 1708 - Cooperative Research and Development Agreement: Technology To Provide Wireless <span class="hlt">Precise</span> Time...</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013</a></p> <p class="result-summary">...Technology To Provide Wireless <span class="hlt">Precise</span> Time; Alternatives to Global <span class="hlt">Positioning</span> Systems...GPS) as a means of providing <span class="hlt">precise</span> time. The alternative under consideration is...technical approach for providing <span class="hlt">precise</span> time using U.S. government facilities...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-11</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">397</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ASPC..481...45R"> <span id="translatedtitle"><span class="hlt">Precision</span> Observational Asteroseismology Using Kepler Spacecraft Data</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Kepler spacecraft has been constantly observing the same stars since March, 2010 and at this <span class="hlt">point</span>, nearly 3 years of data are archived for more than a dozen pulsating sdB stars. With better than a 90% duty cycle, and a new observation every minute, more than a million data <span class="hlt">points</span> per star are available for examination. In this paper, we discuss a few highlights from these data for sdB pulsators, indicating the <span class="hlt">precision</span> of the measurements and including multiple methods for constraining pulsation modes. These Kepler data represent a shift from observationally underconstrained models to <span class="hlt">precision</span> observational asteroseismology to which models will struggle to match.</p> <div class="credits"> <p class="dwt_author">Reed, M.; Foster, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">398</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1985IzKry..73..189N"> <span id="translatedtitle">Systematic <span class="hlt">pointing</span> errors of a 22-m radio telescope</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A means of analyzing and calculating the systematic <span class="hlt">pointing</span> errors of the Crimean Astrophysical Observatory RT-22 radio telescope using discrete radio source data is proposed. It is shown that the derived analytical expressions are adequate for error approximation. The standard deviation after allowance for systematic errors is about 10 arcsec with respect to both coordinates; the <span class="hlt">pointing</span> deviations are distributed randomly. The telescope's vertical axis inclination is measured, and the coordinates of its astronomical <span class="hlt">position</span> are determined with greater <span class="hlt">precision</span>. Factors leading to systematic <span class="hlt">pointing</span> error instabilities are established.</p> <div class="credits"> <p class="dwt_author">Nesterov, N. S.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">399</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24725878"> <span id="translatedtitle">An improved procedure for separation/purification of boron from complex matrices and high-<span class="hlt">precision</span> measurement of boron isotopes by <span class="hlt">positive</span> thermal ionization and multicollector inductively coupled plasma mass spectrometry.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">In order to eliminate boron loss and potential isotopic fractionation during chemical pretreatment of natural samples with complex matrices, a three-column ion-exchange separation/purification procedure has been modified, which ensures more than 98% recovery of boron from each step for a wide range of sample matrices, and is applicable for boron isotope analysis by both TIMS and MC-ICP-MS. The PTIMS-Cs2BO2(+)-static double collection method was developed, ensuring simultaneous collection of (133)Cs2(11)B(16)O2(+)(m/z 309) and (133)Cs2(10)B(16)O2(+) (m/z 308) ions in adjacent H3-H4 Faraday cups with typical zoom optics parameters (Focus Quad: 15 V, Dispersion Quad: -85 V). The external reproducibilities of the measured (11)B/(10)B ratios of the NIST 951 boron standard solutions of 1000 ng, 100 ng and 10 ng of boron by PTIMS method are ±0.06‰, ±0.16‰ and ±0.25‰, respectively, which indicates excellent <span class="hlt">precision</span> can be achieved for boron isotope measurement at nanogram level boron in natural samples. An on-peak zero blank correction procedure was employed to correct the residual boron signals effect in MC-ICP-MS, which gives consistent ?(11)B values with a mean of 39.66±0.35‰ for seawater in the whole range of boron content from 5 ppb to 200 ppb, ensuring accurate boron isotope analysis in few ppb boron. With the improved protocol, consistent results between TIMS and MC-ICP-MS data were obtained in typical geological materials within a wide span of ?(11)B values ranging from -25‰ to +40‰. PMID:24725878</p> <div class="credits"> <p class="dwt_author">Wei, Hai-Zhen; Jiang, Shao-Yong; Hemming, N Gary; Yang, Jing-Hong; Yang, Tao; Wu, He-Pin; Yang, Tang-Li; Yan, Xiong; Pu, Wei</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">400</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010SPIE.7544E..38S"> <span id="translatedtitle">Calibration method for large internal micrometer with three-<span class="hlt">point</span> contact</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">With the development of the machinery industry and the enhancement of the components <span class="hlt">precision</span>, the large internal micrometer with three-<span class="hlt">point</span> contact broadens its field of application. However, the calibration method for large internal micrometer with three-<span class="hlt">point</span> contact has not been solved completely. In order to solve all the calibration problems for large internal micrometer with three-<span class="hlt">point</span> contact of 100mm and above, this paper proposes a new calibration method. Different from that of the calibration criterion JJF1091-2002 in Micrometer for Measuring inside Dimension, this method mainly uses the high <span class="hlt">precision</span> CMM to calibrate the internal micrometer with three-<span class="hlt">point</span> contact. The procedures are as follows. First, use the CMM to scan and measure the internal micrometer with three-<span class="hlt">point</span> contact. Next, make the evaluation of scanning <span class="hlt">point</span> with the method of the maximum circumcircle to get the CMM measurements of the internal micrometer with three-<span class="hlt">point</span> contact in different diameter <span class="hlt">positions</span>. Second, use the internal micrometer with three-<span class="hlt">point</span> contact to measure any standard ring gauges within its measuring range to get the indicating value which is also named as reference <span class="hlt">point</span> indicating value. Third, analyze the diameter value got by using the CMM to measure the internal micrometer with three-<span class="hlt">point</span> contact in different <span class="hlt">positions</span> and the reference <span class="hlt">point</span> indicating value. After data processing, the error of indication in different <span class="hlt">positions</span> can be got. Last, analyze the uncertainty of measurement to test its feasibility.</p> <div class="credits"> <p class="dwt_author">Sui, Rui Tao</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-08-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_19");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return 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title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">401</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1998SPIE.3365...22H"> <span id="translatedtitle">Acquisition, tracking, and <span class="hlt">pointing</span> system for self-protection applications</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A state-of-the-art acquisition/tracking/<span class="hlt">positioning</span> (ATP) system for vehicle protection and area defense application is presently being developed. The ATP system, referred to as the high performance laser fire control system, has been designed to automatically acquire, track, rangefind and designate top attack weapons, such as mortars and artillery, as well as line-of-sight type weapons, such as anti-tank guided missiles and anti-tank projectiles. The ATP mission scenario requires full hemispherical coverage, extremely high acceleration capabilities, <span class="hlt">precision</span> stabilization, and <span class="hlt">precision</span> <span class="hlt">pointing</span>.</p> <div class="credits"> <p class="dwt_author">Hammer, Steven J.; Stockum, Larry A.; Chesser, Douglas E.; Miller, John E.</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">402</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850000518&hterms=hydraulic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2522hydraulic%2522"> <span id="translatedtitle">Hydraulic Cylinder With an Integral <span class="hlt">Position</span> Indicator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Linear variable differential transformer (LVDT) incorporated within cylinder of hydraulic actuator gives <span class="hlt">precise</span> readout of <span class="hlt">position</span> of piston relative to cylinder. LVDT contained completely within actuator. System requires <span class="hlt">precise</span> <span class="hlt">positioning</span> and <span class="hlt">position</span> readout for computer control of model motions. Minimal space available for motion cylinders, and <span class="hlt">precise</span>, continuous <span class="hlt">position</span> readout (with no steps or pulses) required. Device provides continuous and accurate <span class="hlt">position</span> indication of a hydraulic cylinder by means of integral, coaxially mounted LVDT.</p> <div class="credits"> <p class="dwt_author">Goodwin, G. O.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">403</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3970034"> <span id="translatedtitle">Developing <span class="hlt">Precision</span> Stroke Imaging</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Stroke experts stand at the cusp of a unique opportunity to advance the care of patients with cerebrovascular disorders across the globe through improved imaging approaches. NIH initiatives including the Stroke Progress Review Group promotion of imaging in stroke research and the newly established NINDS Stroke Trials network converge with the rapidly evolving concept of <span class="hlt">precision</span> medicine. <span class="hlt">Precision</span> stroke imaging portends the coming shift to individualized approaches to cerebrovascular disorders where big data may be leveraged to identify and manage stroke risk with specific treatments utilizing an improved neuroimaging infrastructure, data collection, and analysis. We outline key aspects of the stroke imaging field where <span class="hlt">precision</span> medicine may rapidly transform the care of stroke patients in the next few years.</p> <div class="credits"> <p class="dwt_author">Feldmann, Edward; Liebeskind, David S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">404</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/564417"> <span id="translatedtitle">Profile Guided Code <span class="hlt">Positioning</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper presents the results of our investigation of code <span class="hlt">positioning</span> techniques using execution profile data as input into the compilation process. The primary objective of the <span class="hlt">positioning</span> is to reduce the overhead of the instruction memory hierarchy. After initial investigation in the literature, we decided to implement two prototypes for the Hewlett-Packard <span class="hlt">Precision</span> Architecture (PA-RISC). The first, built on</p> <div class="credits"> <p class="dwt_author">Karl Pettis; Robert C. Hansen</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">405</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JGRB..119.3823H"> <span id="translatedtitle">Distribution and mitigation of higher-order ionospheric effects on <span class="hlt">precise</span> GNSS processing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Higher-order ionospheric effects (I2+) are one of the main limiting factors in very <span class="hlt">precise</span> Global Navigation Satellite Systems (GNSS) processing, for applications where millimeter accuracy is demanded. This paper summarizes a comprehensive study of the I2+ effects in range and in GNSS <span class="hlt">precise</span> products such as receiver <span class="hlt">position</span> and clock, tropospheric delay, geocenter offset, and GNSS satellite <span class="hlt">position</span> and clock. All the relevant higher-order contributions are considered: second and third orders, geometric bending, and slant total electron content (dSTEC) bending (i.e., the difference between the STEC for straight and bent paths). Using a realistic simulation with representative solar maximum conditions on GPS signals, both the effects and mitigation errors are analyzed. The usage of the combination of multifrequency L band observations has to be rejected due to its increased noise level. The results of the study show that the main two effects in range are the second-order ionospheric and dSTEC terms, with peak values up to 2 cm. Their combined impacts on the <span class="hlt">precise</span> GNSS satellite products affects the satellite Z coordinates (up to +1 cm) and satellite clocks (more than ±20 ps). Other <span class="hlt">precise</span> products are affected at the millimeter level. After correction the impact on all the <span class="hlt">precise</span> GNSS products is reduced below 5 mm. We finally show that the I2+ impact on a <span class="hlt">Precise</span> <span class="hlt">Point</span> <span class="hlt">Positioning</span> (PPP) user is lower than the current uncertainties of the PPP solutions, after applying consistently the <span class="hlt">precise</span> products (satellite orbits and clocks) obtained under I2+ correction.</p> <div class="credits"> <p class="dwt_author">Hernández-Pajares, Manuel; Aragón-Ángel, Àngela; Defraigne, Pascale; Bergeot, Nicolas; Prieto-Cerdeira, Roberto; García-Rigo, Alberto</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">406</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009LNCS.5734..736R"> <span id="translatedtitle"><span class="hlt">Points</span> on Computable Curves of Computable Lengths</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A computable plane curve is defined as the image of a computable real function from a closed interval to the real plane. As it is showed by Ko [7] that the length of a computable curve is not necessarily computable, even if the length is finite. Therefore, the set of the computable curves of computable lengths is different from the set of the computable curves of finite lengths. In this paper we show further that the <span class="hlt">points</span> covered by these two sets of curves are different as well. More <span class="hlt">precisely</span>, we construct a computable curve K of a finite length and a <span class="hlt">point</span> z on the curve K such that the <span class="hlt">point</span> z does not belong to any computable curve of computable length. This gives also a <span class="hlt">positive</span> answer to an open question of Gu, Lutz and Mayordomo in [4].</p> <div class="credits"> <p class="dwt_author">Rettinger, Robert; Zheng, Xizhong</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">407</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020083303&hterms=plastic+toxic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dplastic%2Btoxic"> <span id="translatedtitle"><span class="hlt">Precision</span> Heating Process</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A heat sealing process was developed by SEBRA based on technology that originated in work with NASA's Jet Propulsion Laboratory. The project involved connecting and transferring blood and fluids between sterile plastic containers while maintaining a closed system. SEBRA markets the PIRF Process to manufacturers of medical catheters. It is a <span class="hlt">precisely</span> controlled method of heating thermoplastic materials in a mold to form or weld catheters and other products. The process offers advantages in fast, <span class="hlt">precise</span> welding or shape forming of catheters as well as applications in a variety of other industries.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">408</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/10176405"> <span id="translatedtitle">High <span class="hlt">precision</span> Woelter optic calibration facility</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We have developed an off-line facility for very <span class="hlt">precise</span> characterization of the reflectance and spatial resolution of the grazing incidence Woelter Type 1 x-ray optics used at Nova. The primary component of the facility is a high brightness, ``<span class="hlt">point</span>`` x-ray source consisting of a focussed DC electron beam incident onto a <span class="hlt">precision</span> manipulated target/pinhole array. The data are recorded with a selection of detectors. For imaging measurements we use direct exposure x-ray film modules or an x-ray CCD camera. For energy-resolved reflectance measurements, we use lithium drifted silicon detectors and a proportional counter. An in situ laser alignment system allows <span class="hlt">precise</span> location and rapid periodic alignment verification of the x-ray <span class="hlt">point</span> source, the statically mounted Woelter optic, and the chosen detector.</p> <div class="credits"> <p class="dwt_author">Morales, R.I.; Remington, B.A.; Schwinn, T.</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-05-02</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">409</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/19276968"> <span id="translatedtitle">Thermomechanically Driven Polymer Actuator for High-<span class="hlt">Precision</span> Optical Alignment</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Precise</span> thermomechanical <span class="hlt">positioning</span> has been demonstrated in an actuator device based on a silicone elastomer with a high thermal expansion coefficient. The actuator performance has been characterized using optical microscopy, and the actuator has been deployed in an optical coupling experiment to demonstrate the <span class="hlt">precise</span> <span class="hlt">positioning</span> of a ball lens between two single-mode fibers. Tuning of the coupling efficiency has</p> <div class="credits"> <p class="dwt_author">G. Jordan; A. M. Lyons</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">410</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/872679"> <span id="translatedtitle"><span class="hlt">Precision</span> tip-tilt-piston actuator that provides exact constraint</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A <span class="hlt">precision</span> device which can <span class="hlt">precisely</span> actuate three degrees of freedom of an optic mount, commonly referred to as tip, tilt, and piston. The device consists of three identical flexure mechanisms, an optic mount to be supported and <span class="hlt">positioned</span>, a structure that supports the flexure mechanisms, and three commercially available linear actuators. The advantages of the <span class="hlt">precision</span> device is in the arrangement of the constraints offered by the flexure mechanism and not in the particular design of the flexure mechanisms, as other types of mechanisms could be substituted. Each flexure mechanism constrains two degrees of freedom in the plane of the mechanisms and one direction is actuated. All other degrees of freedom are free to move within the range of flexure mechanisms. Typically, three flexure mechanisms are equally spaced in angle about to optic mount and arranged so that each actuated degree of freedom is perpendicular to the plane formed by the optic mount. This arrangement exactly constrains the optic mount and allows arbitrary actuated movement of the plane within the range of the flexure mechanisms. Each flexure mechanism provides a mechanical advantage, typically on the order of 5:1, between the commercially available actuator and the functional <span class="hlt">point</span> on the optic mount. This improves resolution by the same ratio and stiffness by the square of the ratio.</p> <div class="credits"> <p class="dwt_author">Hale, Layton C. (Livermore, CA)</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">411</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26299310"> <span id="translatedtitle"><span class="hlt">Precise</span> magnetic sensors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Can magnetoresistors replace fluxgate sensors in <span class="hlt">precise</span> applications such as navigation and detection of metal objects? Anisotropic Magnetoresistors (AMRs) and Giant Magnetoresistors (GMRs) can reach 10nT resolution. It is possible to improve their stability by ac techniques, but the electronics becomes complex and consumes more power. If size is not limited, fluxgate sensors are still the winners.</p> <div class="credits"> <p class="dwt_author">Michal Vopálenský; Pavel Ripka; Anton??n Platil</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">412</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA519017"> <span id="translatedtitle">High <span class="hlt">Precision</span> GPS Measurements.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The objective of this project is to develop high <span class="hlt">precision</span> GPS receivers by utilizing modernized GPS signals at L1, L2, and L5 frequencies to mitigate GPS measurement errors. For each successfully acquired and tracked GPS signal, a GPS receiver generates ...</p> <div class="credits"> <p class="dwt_author">F. Van Graas Y. Morton</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">413</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/7254681"> <span id="translatedtitle"><span class="hlt">Precision</span> liquid level sensor</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A <span class="hlt">precision</span> liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge. 2 figs.</p> <div class="credits"> <p class="dwt_author">Field, M.E.; Sullivan, W.H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-29</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">414</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5511776"> <span id="translatedtitle"><span class="hlt">Precision</span> tests of QED</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The major <span class="hlt">precision</span> tests of QED are reviewed. At the present time, there are no serious conflicts between theory and experiment. However, there are various possibilities for refining the tests and some of them depend on better information from high energy physics experiments.</p> <div class="credits"> <p class="dwt_author">Yennie, D.R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-11-15</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">415</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA008294"> <span id="translatedtitle">A <span class="hlt">Precision</span> CTD Microprofiler.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This paper describes a conductivity-temperature-depth (CTD) system designed for <span class="hlt">precise</span> fine scale measurements of salinity and temperature in the deep ocean. The conductivity sensor is a miniature (8 mm long, 2 mm I.D.) four electrode cell. Temperature i...</p> <div class="credits"> <p class="dwt_author">N. L. Brown</p> <p class="dwt_publisher"></p> <p class="publishDate">1974-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">416</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51855238"> <span id="translatedtitle">On the range resolution of <span class="hlt">point</span> targets with FMCW radar systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The spectral analysis of the low pass filtered echo signals of a stationary <span class="hlt">point</span> target was carried out starting with the <span class="hlt">precise</span> <span class="hlt">position</span> of the transmit signal of a Frequency Modulated Continuous-Wave (FMCW) radar operated with sawtooth modulation and assuming a signal transit time which is short compared with the modulation period. It can be stated that the minimum detectable</p> <div class="credits"> <p class="dwt_author">Reinhard Hammel</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">417</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/15211313"> <span id="translatedtitle">A class of simplicial restart fixed <span class="hlt">point</span> algorithms without an extra dimension</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In an earlier paper we introduced an algorithm for approximating a fixed <span class="hlt">point</span> of a mapping on the product space of unit simplices. Ideas of that paper are used to construct a class of triangulations ofRn. More <span class="hlt">precisely</span>, for somek, 1 =k = n, and <span class="hlt">positive</span> integersm1 ? , mk with sumn, a triangulation ofRn is obtained by triangulating the</p> <div class="credits"> <p class="dwt_author">G. van der Laan; A. J. J. Talman</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">418</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.cs.sfu.ca/~mark/ftp/Cic98/cic98_wppPositivity.pdf"> <span id="translatedtitle">White-<span class="hlt">Point</span> Preservation Enforces <span class="hlt">Positivity</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">It is commonplace to use a linear transform to map device RGBs to XYZs. Two particular types of trans- forms have been developed based on the assumptions that we either maximally ignorant or maximally prescient about the world. Under the maximum ignorance assumption, it is assumed that nothing is known about the spectral statistics of the world and so the</p> <div class="credits"> <p class="dwt_author">Graham D. Finlayson</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">419</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4047838"> <span id="translatedtitle">Chemical patterning on preformed porous silicon photonic crystals: towards multiplex detection of protease activity at <span class="hlt">precise</span> <span class="hlt">positions</span>† †Electronic supplementary information (ESI) available: SEM images, XPS result and more optical reflectivity data. See DOI: 10.1039/c4tb00281d Click here for additional data file.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Porous silicon (PSi) rugate filters modified with alkyne-terminated monolayers were chemically patterned using a combination of photolithography of photoresist and click chemistry. Two chemical functionalities were obtained by conjugating, via click reactions, ethylene glycol moieties containing two different terminal groups to discrete areas towards the exterior of a PSi rugate filter. The patterning of biological species to the functionalized surface was demonstrated through the conjugation of fluorescein isothiocyanate labelled bovine serum albumin (FITC-BSA). Fluorescence microscopy showed selective <span class="hlt">positioning</span> of FITC-BSA at discretely functionalized areas. Meanwhile, the optical information from <span class="hlt">precisely</span> defined <span class="hlt">positions</span> on the patterned surface was monitored by optical reflectivity measurements. The optical measurements revealed successful step-wise chemical functionalization followed by immobilization of gelatin. Multiplex detection of protease activity from different array elements on the patterned surface was demonstrated by monitoring the blue shifts in the reflectivity spectra resulted from the digestion of gelatin by subtilisin. <span class="hlt">Precise</span> information from both individual elements and average population was acquired. This technique is important for the development of PSi into a microarray platform for highly parallel biosensing applications, especially for cell-based assays.</p> <div class="credits"> <p class="dwt_author">Zhu, Ying; Soeriyadi, Alexander H.; Parker, Stephen G.; Reece, Peter J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">420</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2858443"> <span id="translatedtitle"><span class="hlt">Precision</span> and scaling in morphogen gradient read-out</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Morphogen gradients infer cell fate as a function of cellular <span class="hlt">position</span>. Experiments in Drosophila embryos have shown that the Bicoid (Bcd) gradient is <span class="hlt">precise</span> and exhibits some degree of scaling. We present experimental results on the <span class="hlt">precision</span> of Bcd target genes for embryos with a single, double or quadruple dose of bicoid demonstrating that <span class="hlt">precision</span> is highest at mid-embryo and <span class="hlt">position</span> dependent, rather than gene dependent. This confirms that the major contribution to <span class="hlt">precision</span> is achieved already at the Bcd gradient formation. Modeling this dynamic process, we investigate <span class="hlt">precision</span> for inter-embryo fluctuations in different parameters affecting gradient formation. Within our modeling framework, the observed <span class="hlt">precision</span> can only be achieved by a transient Bcd profile. Studying different extensions of our modeling framework reveals that scaling is generally <span class="hlt">position</span> dependent and decreases toward the posterior pole. Our measurements confirm this trend, indicating almost perfect scaling except for anterior most expression domains, which overcompensate fluctuations in embryo length.</p> <div class="credits"> <p class="dwt_author">Morton de Lachapelle, Aitana; Bergmann, Sven</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_20");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> 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